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[nit.git] / src / abstract_compiler.nit

# This file is part of NIT ( http://www.nitlanguage.org ).
#
# Copyright 2012 Jean Privat <jean@pryen.org>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Abstract compiler
module abstract_compiler

import literal
import typing
import auto_super_init

# Add compiling options
redef class ToolContext
        # --output
        var opt_output: OptionString = new OptionString("Output file", "-o", "--output")
        # --no-cc
        var opt_no_cc: OptionBool = new OptionBool("Do not invoke C compiler", "--no-cc")
        # --make-flags
        var opt_make_flags: OptionString = new OptionString("Additional options to make", "--make-flags")
        # --hardening
        var opt_hardening: OptionBool = new OptionBool("Generate contracts in the C code against bugs in the compiler", "--hardening")
        # --no-shortcut-range
        var opt_no_shortcut_range: OptionBool = new OptionBool("Always insantiate a range and its iterator on 'for' loops", "--no-shortcut-range")
        # --no-check-covariance
        var opt_no_check_covariance: OptionBool = new OptionBool("Disable type tests of covariant parameters (dangerous)", "--no-check-covariance")
        # --no-check-initialization
        var opt_no_check_initialization: OptionBool = new OptionBool("Disable isset tests at the end of constructors (dangerous)", "--no-check-initialization")
        # --no-check-assert
        var opt_no_check_assert: OptionBool = new OptionBool("Disable the evaluation of explicit 'assert' and 'as' (dangerous)", "--no-check-assert")
        # --no-check-autocast
        var opt_no_check_autocast: OptionBool = new OptionBool("Disable implicit casts on unsafe expression usage (dangerous)", "--no-check-autocast")
        # --no-check-other
        var opt_no_check_other: OptionBool = new OptionBool("Disable implicit tests: unset attribute, null receiver (dangerous)", "--no-check-other")
        # --typing-test-metrics
        var opt_typing_test_metrics: OptionBool = new OptionBool("Enable static and dynamic count of all type tests", "--typing-test-metrics")

        redef init
        do
                super
                self.option_context.add_option(self.opt_output, self.opt_no_cc, self.opt_make_flags, self.opt_hardening, self.opt_no_shortcut_range)
                self.option_context.add_option(self.opt_no_check_covariance, self.opt_no_check_initialization, self.opt_no_check_assert, self.opt_no_check_autocast, self.opt_no_check_other)
                self.option_context.add_option(self.opt_typing_test_metrics)
        end
end

redef class ModelBuilder
        protected fun write_and_make(compiler: AbstractCompiler)
        do
                var mainmodule = compiler.mainmodule

                # Generate the .h and .c files
                # A single C file regroups many compiled rumtime functions
                # Note that we do not try to be clever an a small change in a Nit source file may change the content of all the generated .c files
                var time0 = get_time

                var outname = self.toolcontext.opt_output.value
                if outname == null then
                        outname = "{mainmodule.name}.bin"
                end

                var hfilename = ".nit_compile/{mainmodule.name}.1.h"
                var h = new OFStream.open(hfilename)
                for l in compiler.header.decl_lines do
                        h.write l
                        h.write "\n"
                end
                h.close

                var cfiles = new Array[String]

                var file: nullable OFStream = null
                var count = 0

                ".nit_compile".mkdir
                var i = 0
                for vis in compiler.visitors do
                        count += vis.lines.length
                        if file == null or count > 10000 or vis.file_break then
                                i += 1
                                if file != null then file.close
                                var cfilename = ".nit_compile/{mainmodule.name}.{i}.c"
                                cfiles.add(cfilename)
                                file = new OFStream.open(cfilename)
                                file.write "#include \"{mainmodule.name}.1.h\"\n"
                                count = vis.lines.length
                        end
                        if vis != compiler.header then
                                for l in vis.decl_lines do
                                        file.write l
                                        file.write "\n"
                                end
                        end
                        for l in vis.lines do
                                file.write l
                                file.write "\n"
                        end
                end
                if file != null then file.close

                self.toolcontext.info("Total C source files to compile: {cfiles.length}", 2)

                # Generate the Makefile

                var makename = ".nit_compile/{mainmodule.name}.mk"
                var makefile = new OFStream.open(makename)

                makefile.write("CC = ccache cc\nCFLAGS = -g -O2\nLDFLAGS ?= \nLDLIBS  ?= -lm -lgc\n\n")
                makefile.write("all: {outname}\n\n")

                var ofiles = new Array[String]
                # Compile each generated file
                for f in cfiles do
                        var o = f.strip_extension(".c") + ".o"
                        makefile.write("{o}: {f}\n\t$(CC) $(CFLAGS) -D NONITCNI -c -o {o} {f}\n\n")
                        ofiles.add(o)
                end
                # Compile each required extern body into a specific .o
                for f in compiler.extern_bodies do
                        i += 1
                        var o = ".nit_compile/{mainmodule.name}.{i}.o"
                        makefile.write("{o}: {f}\n\t$(CC) $(CFLAGS) -D NONITCNI -c -o {o} {f}\n\n")
                        ofiles.add(o)
                end
                # Link edition
                makefile.write("{outname}: {ofiles.join(" ")}\n\t$(CC) $(LDFLAGS) -o {outname} {ofiles.join(" ")} $(LDLIBS)\n\n")
                # Clean
                makefile.write("clean:\n\trm {ofiles.join(" ")} 2>/dev/null\n\n")
                makefile.close
                self.toolcontext.info("Generated makefile: {makename}", 2)

                var time1 = get_time
                self.toolcontext.info("*** END COMPILING TO C: {time1-time0} ***", 2)

                # Execute the Makefile

                if self.toolcontext.opt_no_cc.value then return

                time0 = time1
                self.toolcontext.info("*** COMPILING C ***", 1)
                var makeflags = self.toolcontext.opt_make_flags.value
                if makeflags == null then makeflags = ""
                self.toolcontext.info("make -B -f {makename} -j 4 {makeflags}", 2)

                var res
                if self.toolcontext.verbose_level >= 3 then
                        res = sys.system("make -B -f {makename} -j 4 {makeflags} 2>&1")
                else
                        res = sys.system("make -B -f {makename} -j 4 {makeflags} 2>&1 >/dev/null")
                end
                if res != 0 then
                        toolcontext.error(null, "make failed! Error code: {res}.")
                end

                time1 = get_time
                self.toolcontext.info("*** END COMPILING C: {time1-time0} ***", 2)
        end
end

# Singleton that store the knowledge about the compilation process
abstract class AbstractCompiler
        type VISITOR: AbstractCompilerVisitor

        # The main module of the program
        var mainmodule: MModule protected writable

        # The modeulbuilder used to know the model and the AST
        var modelbuilder: ModelBuilder protected writable

        # Is hardening asked? (see --hardening)
        fun hardening: Bool do return self.modelbuilder.toolcontext.opt_hardening.value

        init(mainmodule: MModule, modelbuilder: ModelBuilder)
        do
                self.mainmodule = mainmodule
                self.modelbuilder = modelbuilder
        end

        # Force the creation of a new file
        # The point is to avoid contamination between must-be-compiled-separately files
        fun new_file
        do
                var v = self.new_visitor
                v.file_break = true
        end

        # The list of all associated visitors
        # Used to generate .c files
        # FIXME: should not be vistors but just somewhere to store lines
        var visitors: List[VISITOR] = new List[VISITOR]

        # Initialize a visitor specific for a compiler engine
        fun new_visitor: VISITOR is abstract

        # Where global declaration are stored (the main .h)
        #
        # FIXME: should not be a visitor but just somewhere to store lines
        # FIXME: should not have a global .h since it does not help recompilations
        var header: VISITOR writable

        # Compile C headers
        # This method call compile_header_strucs method that has to be refined
        fun compile_header do
                var v = self.header
                self.header.add_decl("#include <stdlib.h>")
                self.header.add_decl("#include <stdio.h>")
                self.header.add_decl("#include <string.h>")
                self.header.add_decl("#ifndef NOBOEHM")
                self.header.add_decl("#include <gc/gc.h>")
                self.header.add_decl("#ifdef NOBOEHM_ATOMIC")
                self.header.add_decl("#undef GC_MALLOC_ATOMIC")
                self.header.add_decl("#define GC_MALLOC_ATOMIC(x) GC_MALLOC(x)")
                self.header.add_decl("#endif /*NOBOEHM_ATOMIC*/")
                self.header.add_decl("#else /*NOBOEHM*/")
                self.header.add_decl("#define GC_MALLOC(x) calloc(1, (x))")
                self.header.add_decl("#define GC_MALLOC_ATOMIC(x) calloc(1, (x))")
                self.header.add_decl("#endif /*NOBOEHM*/")

                compile_header_structs

                # Global variable used by the legacy native interface
                self.header.add_decl("extern int glob_argc;")
                self.header.add_decl("extern char **glob_argv;")
                self.header.add_decl("extern val *glob_sys;")
        end

        # Declaration of structures the live Nit types
        protected fun compile_header_structs is abstract

        # Generate the main C function.
        # This function:
        #       * allocate the Sys object if it exists
        #       * call init if is exists
        #       * call main if it exists
        fun compile_main_function
        do
                var v = self.new_visitor
                v.add_decl("int glob_argc;")
                v.add_decl("char **glob_argv;")
                v.add_decl("val *glob_sys;")

                if self.modelbuilder.toolcontext.opt_typing_test_metrics.value then
                        for tag in count_type_test_tags do
                                v.add_decl("long count_type_test_resolved_{tag};")
                                v.add_decl("long count_type_test_unresolved_{tag};")
                                v.add_decl("long count_type_test_skipped_{tag};")
                                v.compiler.header.add_decl("extern long count_type_test_resolved_{tag};")
                                v.compiler.header.add_decl("extern long count_type_test_unresolved_{tag};")
                                v.compiler.header.add_decl("extern long count_type_test_skipped_{tag};")
                        end
                end
                v.add_decl("int main(int argc, char** argv) \{")
                v.add("glob_argc = argc; glob_argv = argv;")
                var main_type = mainmodule.sys_type
                if main_type != null then
                        var mainmodule = v.compiler.mainmodule
                        var glob_sys = v.init_instance(main_type)
                        v.add("glob_sys = {glob_sys};")
                        var main_init = mainmodule.try_get_primitive_method("init", main_type)
                        if main_init != null then
                                v.send(main_init, [glob_sys])
                        end
                        var main_method = mainmodule.try_get_primitive_method("main", main_type)
                        if main_method != null then
                                v.send(main_method, [glob_sys])
                        end
                end

                if self.modelbuilder.toolcontext.opt_typing_test_metrics.value then
                        v.add_decl("long count_type_test_resolved_total = 0;")
                        v.add_decl("long count_type_test_unresolved_total = 0;")
                        v.add_decl("long count_type_test_skipped_total = 0;")
                        v.add_decl("long count_type_test_total_total = 0;")
                        for tag in count_type_test_tags do
                                v.add_decl("long count_type_test_total_{tag};")
                                v.add("count_type_test_total_{tag} = count_type_test_resolved_{tag} + count_type_test_unresolved_{tag} + count_type_test_skipped_{tag};")
                                v.add("count_type_test_resolved_total += count_type_test_resolved_{tag};")
                                v.add("count_type_test_unresolved_total += count_type_test_unresolved_{tag};")
                                v.add("count_type_test_skipped_total += count_type_test_skipped_{tag};")
                                v.add("count_type_test_total_total += count_type_test_total_{tag};")
                        end
                        v.add("printf(\"# dynamic count_type_test: total %l\\n\");")
                        v.add("printf(\"\\tresolved\\tunresolved\\tskipped\\ttotal\\n\");")
                        var tags = count_type_test_tags.to_a
                        tags.add("total")
                        for tag in tags do
                                v.add("printf(\"{tag}\");")
                                v.add("printf(\"\\t%ld (%.2f%%)\", count_type_test_resolved_{tag}, 100.0*count_type_test_resolved_{tag}/count_type_test_total_total);")
                                v.add("printf(\"\\t%ld (%.2f%%)\", count_type_test_unresolved_{tag}, 100.0*count_type_test_unresolved_{tag}/count_type_test_total_total);")
                                v.add("printf(\"\\t%ld (%.2f%%)\", count_type_test_skipped_{tag}, 100.0*count_type_test_skipped_{tag}/count_type_test_total_total);")
                                v.add("printf(\"\\t%ld (%.2f%%)\\n\", count_type_test_total_{tag}, 100.0*count_type_test_total_{tag}/count_type_test_total_total);")
                        end
                end
                v.add("return 0;")
                v.add("\}")
        end

        # look for a needed .h and .c file for a given .nit source-file
        # FIXME: bad API, parameter should be a MModule, not its source-file
        fun add_extern(file: String)
        do
                file = file.strip_extension(".nit")
                var tryfile = file + ".nit.h"
                if tryfile.file_exists then
                        self.header.add_decl("#include \"{"..".join_path(tryfile)}\"")
                end
                tryfile = file + "_nit.h"
                if tryfile.file_exists then
                        self.header.add_decl("#include \"{"..".join_path(tryfile)}\"")
                end
                tryfile = file + ".nit.c"
                if tryfile.file_exists then
                        self.extern_bodies.add(tryfile)
                end
                tryfile = file + "_nit.c"
                if tryfile.file_exists then
                        self.extern_bodies.add(tryfile)
                end
        end

        # List of additional .c files required to compile (native interface)
        var extern_bodies = new ArraySet[String]

        # Generate code that check if an instance is correctly initialized
        fun generate_check_init_instance(mtype: MClassType) is abstract

        # Generate code that initialize the attributes on a new instance
        fun generate_init_attr(v: VISITOR, recv: RuntimeVariable, mtype: MClassType)
        do
                var cds = mtype.collect_mclassdefs(self.mainmodule).to_a
                self.mainmodule.linearize_mclassdefs(cds)
                for cd in cds do
                        var n = self.modelbuilder.mclassdef2nclassdef[cd]
                        for npropdef in n.n_propdefs do
                                if npropdef isa AAttrPropdef then
                                        npropdef.init_expr(v, recv)
                                end
                        end
                end
        end

        # Generate code that check if an attribute is correctly initialized
        fun generate_check_attr(v: VISITOR, recv: RuntimeVariable, mtype: MClassType)
        do
                var cds = mtype.collect_mclassdefs(self.mainmodule).to_a
                self.mainmodule.linearize_mclassdefs(cds)
                for cd in cds do
                        var n = self.modelbuilder.mclassdef2nclassdef[cd]
                        for npropdef in n.n_propdefs do
                                if npropdef isa AAttrPropdef then
                                        npropdef.check_expr(v, recv)
                                end
                        end
                end
        end

        # stats

        var count_type_test_tags: Array[String] = ["isa", "as", "auto", "covariance", "erasure"]
        var count_type_test_resolved: HashMap[String, Int] = init_count_type_test_tags
        var count_type_test_unresolved: HashMap[String, Int] = init_count_type_test_tags
        var count_type_test_skipped: HashMap[String, Int] = init_count_type_test_tags

        protected fun init_count_type_test_tags: HashMap[String, Int]
        do
                var res = new HashMap[String, Int]
                for tag in count_type_test_tags do
                        res[tag] = 0
                end
                return res
        end

        # Display stats about compilation process
        # Metrics used:
        #       * type tests against resolved types (x isa Collection[Animal])
        #       * type tests against unresolved types (x isa Collection[E])
        #       * type tests skipped
        #       * type tests total
        #       *
        fun display_stats
        do
                if self.modelbuilder.toolcontext.opt_typing_test_metrics.value then
                        print "# static count_type_test"
                        print "\tresolved:\tunresolved\tskipped\ttotal"
                        var count_type_test_total = init_count_type_test_tags
                        count_type_test_resolved["total"] = 0
                        count_type_test_unresolved["total"] = 0
                        count_type_test_skipped["total"] = 0
                        count_type_test_total["total"] = 0
                        for tag in count_type_test_tags do
                                count_type_test_total[tag] = count_type_test_resolved[tag] + count_type_test_unresolved[tag] + count_type_test_skipped[tag]
                                count_type_test_resolved["total"] += count_type_test_resolved[tag]
                                count_type_test_unresolved["total"] += count_type_test_unresolved[tag]
                                count_type_test_skipped["total"] += count_type_test_skipped[tag]
                                count_type_test_total["total"] += count_type_test_total[tag]
                        end
                        var count_type_test = count_type_test_total["total"]
                        var tags = count_type_test_tags.to_a
                        tags.add("total")
                        for tag in tags do
                                printn tag
                                printn "\t{count_type_test_resolved[tag]} ({div(count_type_test_resolved[tag],count_type_test)}%)"
                                printn "\t{count_type_test_unresolved[tag]} ({div(count_type_test_unresolved[tag],count_type_test)}%)"
                                printn "\t{count_type_test_skipped[tag]} ({div(count_type_test_skipped[tag],count_type_test)}%)"
                                printn "\t{count_type_test_total[tag]} ({div(count_type_test_total[tag],count_type_test)}%)"
                                print ""
                        end
                end
        end

        # Division facility
        # Avoid division by zero by returning the string "n/a"
        fun div(a,b:Int):String
        do
                if b == 0 then return "n/a"
                return ((a*10000/b).to_f / 100.0).to_precision(2)
        end
end

# A visitor on the AST of property definition that generate the C code.
abstract class AbstractCompilerVisitor

        type COMPILER: AbstractCompiler

        # The associated compiler
        var compiler: COMPILER

        # The current visited AST node
        var current_node: nullable ANode writable = null

        # The current Frame
        var frame: nullable Frame writable

        # Alias for self.compiler.mainmodule.object_type
        fun object_type: MClassType do return self.compiler.mainmodule.object_type

        # Alias for self.compiler.mainmodule.bool_type
        fun bool_type: MClassType do return self.compiler.mainmodule.bool_type

        var file_break: Bool = false

        init(compiler: COMPILER)
        do
                self.compiler = compiler
                compiler.visitors.add(self)
        end

        # Force to get the primitive class named `name' or abort
        fun get_class(name: String): MClass do return self.compiler.mainmodule.get_primitive_class(name)

        # Force to get the primitive property named `name' in the instance `recv' or abort
        fun get_property(name: String, recv: MType): MMethod
        do
                return self.compiler.modelbuilder.force_get_primitive_method(self.current_node.as(not null), name, recv, self.compiler.mainmodule)
        end

        fun compile_callsite(callsite: CallSite, args: Array[RuntimeVariable]): nullable RuntimeVariable
        do
                return self.send(callsite.mproperty, args)
        end

        fun calloc_array(ret_type: MType, arguments: Array[RuntimeVariable]) is abstract

        fun native_array_def(pname: String, ret_type: nullable MType, arguments: Array[RuntimeVariable]) is abstract

        # Transform varargs, in raw arguments, into a single argument of type Array
        # Note: this method modify the given `args`
        # If there is no vararg, then `args` is not modified.
        fun varargize(mpropdef: MPropDef, msignature: MSignature, args: Array[RuntimeVariable])
        do
                var recv = args.first
                var vararg_rank = msignature.vararg_rank
                if vararg_rank >= 0 then
                        assert args.length >= msignature.arity + 1 # because of self
                        var rawargs = args
                        args = new Array[RuntimeVariable]

                        args.add(rawargs.first) # recv

                        for i in [0..vararg_rank[ do
                                args.add(rawargs[i+1])
                        end

                        var vararg_lastrank = vararg_rank + rawargs.length-1-msignature.arity
                        var vararg = new Array[RuntimeVariable]
                        for i in [vararg_rank..vararg_lastrank] do
                                vararg.add(rawargs[i+1])
                        end

                        var elttype = msignature.mparameters[vararg_rank].mtype
                        args.add(self.vararg_instance(mpropdef, recv, vararg, elttype))

                        for i in [vararg_lastrank+1..rawargs.length-1[ do
                                args.add(rawargs[i+1])
                        end
                        rawargs.clear
                        rawargs.add_all(args)
                end
        end

        # Type handling

        # Anchor a type to the main module and the current receiver
        fun anchor(mtype: MType): MType
        do
                if not mtype.need_anchor then return mtype
                return mtype.anchor_to(self.compiler.mainmodule, self.frame.receiver)
        end

        fun resolve_for(mtype: MType, recv: RuntimeVariable): MType
        do
                if not mtype.need_anchor then return mtype
                return mtype.resolve_for(recv.mcasttype, self.frame.receiver, self.compiler.mainmodule, true)
        end

        # Unsafely cast a value to a new type
        # ie the result share the same C variable but my have a different mcasttype
        # NOTE: if the adaptation is useless then `value' is returned as it.
        # ENSURE: return.name == value.name
        fun autoadapt(value: RuntimeVariable, mtype: MType): RuntimeVariable
        do
                mtype = self.anchor(mtype)
                var valmtype = value.mcasttype
                if valmtype.is_subtype(self.compiler.mainmodule, null, mtype) then
                        return value
                end

                if valmtype isa MNullableType and valmtype.mtype.is_subtype(self.compiler.mainmodule, null, mtype) then
                        var res = new RuntimeVariable(value.name, valmtype, valmtype.mtype)
                        return res
                else
                        var res = new RuntimeVariable(value.name, valmtype, mtype)
                        return res
                end
        end

        # Generate a super call from a method definition
        fun supercall(m: MMethodDef, recvtype: MClassType, args: Array[RuntimeVariable]): nullable RuntimeVariable is abstract

        fun adapt_signature(m: MMethodDef, args: Array[RuntimeVariable]) is abstract

        # Box or unbox a value to another type iff a C type conversion is needed
        # ENSURE: result.mtype.ctype == mtype.ctype
        fun autobox(value: RuntimeVariable, mtype: MType): RuntimeVariable is abstract

        #  Generate a polymorphic subtype test
        fun type_test(value: RuntimeVariable, mtype: MType, tag: String): RuntimeVariable is abstract

        #  Generate the code required to dynamically check if 2 objects share the same runtime type
        fun is_same_type_test(value1, value2: RuntimeVariable): RuntimeVariable is abstract

        #  Generate a Nit "is" for two runtime_variables
        fun equal_test(value1, value2: RuntimeVariable): RuntimeVariable is abstract

        # Sends

        #  Generate a static call on a method definition
        fun call(m: MMethodDef, recvtype: MClassType, args: Array[RuntimeVariable]): nullable RuntimeVariable is abstract

        #  Generate a polymorphic send for the method `m' and the arguments `args'
        fun send(m: MMethod, args: Array[RuntimeVariable]): nullable RuntimeVariable is abstract

        # Generate a monomorphic send for the method `m', the type `t' and the arguments `args'
        fun monomorphic_send(m: MMethod, t: MType, args: Array[RuntimeVariable]): nullable RuntimeVariable
        do
                assert t isa MClassType
                var propdef = m.lookup_first_definition(self.compiler.mainmodule, t)
                return self.call(propdef, t, args)
        end

        # Attributes handling

        # Generate a polymorphic attribute is_set test
        fun isset_attribute(a: MAttribute, recv: RuntimeVariable): RuntimeVariable is abstract

        # Generate a polymorphic attribute read
        fun read_attribute(a: MAttribute, recv: RuntimeVariable): RuntimeVariable is abstract

        # Generate a polymorphic attribute write
        fun write_attribute(a: MAttribute, recv: RuntimeVariable, value: RuntimeVariable) is abstract

        # Checks

        # Add a check and an abort for a null reciever if needed
        fun check_recv_notnull(recv: RuntimeVariable)
        do
                if self.compiler.modelbuilder.toolcontext.opt_no_check_other.value then return

                var maybenull = recv.mcasttype isa MNullableType or recv.mcasttype isa MNullType
                if maybenull then
                        self.add("if ({recv} == NULL) \{")
                        self.add_abort("Reciever is null")
                        self.add("\}")
                end
        end

        # Generate a check-init-instance
        fun check_init_instance(recv: RuntimeVariable, mtype: MClassType) is abstract

        # Names handling

        private var names: HashSet[String] = new HashSet[String]
        private var last: Int = 0

        # Return a new name based on `s' and unique in the visitor
        fun get_name(s: String): String
        do
                if not self.names.has(s) then
                        self.names.add(s)
                        return s
                end
                var i = self.last + 1
                loop
                        var s2 = s + i.to_s
                        if not self.names.has(s2) then
                                self.last = i
                                self.names.add(s2)
                                return s2
                        end
                        i = i + 1
                end
        end

        # Return an unique and stable identifier associated with an escapemark
        fun escapemark_name(e: nullable EscapeMark): String
        do
                assert e != null
                if escapemark_names.has_key(e) then return escapemark_names[e]
                var name = e.name
                if name == null then name = "label"
                name = get_name(name)
                escapemark_names[e] = name
                return name
        end

        private var escapemark_names = new HashMap[EscapeMark, String]

        # Return a "const char*" variable associated to the classname of the dynamic type of an object
        # NOTE: we do not return a RuntimeVariable "NativeString" as the class may not exist in the module/program
        fun class_name_string(value: RuntimeVariable): String is abstract

        # Variables handling

        protected var variables: HashMap[Variable, RuntimeVariable] = new HashMap[Variable, RuntimeVariable]

        # Return the local runtime_variable associated to a Nit local variable
        fun variable(variable: Variable): RuntimeVariable
        do
                if self.variables.has_key(variable) then
                        return self.variables[variable]
                else
                        var name = self.get_name("var_{variable.name}")
                        var mtype = variable.declared_type.as(not null)
                        mtype = self.anchor(mtype)
                        var res = new RuntimeVariable(name, mtype, mtype)
                        self.add_decl("{mtype.ctype} {name} /* var {variable}: {mtype} */;")
                        self.variables[variable] = res
                        return res
                end
        end

        # Return a new uninitialized local runtime_variable
        fun new_var(mtype: MType): RuntimeVariable
        do
                mtype = self.anchor(mtype)
                var name = self.get_name("var")
                var res = new RuntimeVariable(name, mtype, mtype)
                self.add_decl("{mtype.ctype} {name} /* : {mtype} */;")
                return res
        end

        # Return a new uninitialized named runtime_variable
        fun new_named_var(mtype: MType, name: String): RuntimeVariable
        do
                mtype = self.anchor(mtype)
                var res = new RuntimeVariable(name, mtype, mtype)
                self.add_decl("{mtype.ctype} {name} /* : {mtype} */;")
                return res
        end

        # Correctly assign a left and a right value
        # Boxing and unboxing is performed if required
        fun assign(left, right: RuntimeVariable)
        do
                right = self.autobox(right, left.mtype)
                self.add("{left} = {right};")
        end

        # Generate instances

        # Generate a alloc-instance + init-attributes
        fun init_instance(mtype: MClassType): RuntimeVariable is abstract

        # Generate an integer value
        fun int_instance(value: Int): RuntimeVariable
        do
                var res = self.new_var(self.get_class("Int").mclass_type)
                self.add("{res} = {value};")
                return res
        end

        # Generate a string value
        fun string_instance(string: String): RuntimeVariable
        do
                var mtype = self.get_class("String").mclass_type
                var name = self.get_name("varonce")
                self.add_decl("static {mtype.ctype} {name};")
                var res = self.new_var(mtype)
                self.add("if ({name}) \{")
                self.add("{res} = {name};")
                self.add("\} else \{")
                var nat = self.new_var(self.get_class("NativeString").mclass_type)
                self.add("{nat} = \"{string.escape_to_c}\";")
                var res2 = self.init_instance(mtype)
                self.add("{res} = {res2};")
                var length = self.int_instance(string.length)
                self.send(self.get_property("with_native", mtype), [res, nat, length])
                self.check_init_instance(res, mtype)
                self.add("{name} = {res};")
                self.add("\}")
                return res
        end

        # Generate an array value
        fun array_instance(array: Array[RuntimeVariable], elttype: MType): RuntimeVariable is abstract

        # Get an instance of a array for a vararg
        fun vararg_instance(mpropdef: MPropDef, recv: RuntimeVariable, varargs: Array[RuntimeVariable], elttype: MType): RuntimeVariable is abstract

        # Code generation

        private var lines: List[String] = new List[String]
        private var decl_lines: List[String] = new List[String]

        # Add a line in the main part of the generated C
        fun add(s: String) do self.lines.add(s)

        # Add a line in the
        # (used for local or global declaration)
        fun add_decl(s: String) do self.decl_lines.add(s)

        # Return a new local runtime_variable initialized with the C expression `cexpr'.
        fun new_expr(cexpr: String, mtype: MType): RuntimeVariable
        do
                var res = new_var(mtype)
                self.add("{res} = {cexpr};")
                return res
        end

        # Generate generic abort
        # used by aborts, asserts, casts, etc.
        fun add_abort(message: String)
        do
                if self.current_node != null and self.current_node.location.file != null then
                        self.add("fprintf(stderr, \"Runtime error: %s (%s:%d)\\n\", \"{message.escape_to_c}\", \"{self.current_node.location.file.filename.escape_to_c}\", {current_node.location.line_start});")
                else
                        self.add("fprintf(stderr, \"Runtime error: %s\\n\", \"{message.escape_to_c}\");")
                end
                self.add("exit(1);")
        end

        # Generate a return with the value `s'
        fun ret(s: RuntimeVariable)
        do
                self.assign(self.frame.returnvar.as(not null), s)
                self.add("goto {self.frame.returnlabel.as(not null)};")
        end

        # Compile a statement (if any)
        fun stmt(nexpr: nullable AExpr)
        do
                if nexpr == null then return
                var old = self.current_node
                self.current_node = nexpr
                nexpr.stmt(self)
                self.current_node = old
        end

        # Compile an expression an return its result
        # `mtype` is the expected return type, pass null if no specific type is expected.
        fun expr(nexpr: AExpr, mtype: nullable MType): RuntimeVariable
        do
                var old = self.current_node
                self.current_node = nexpr
                var res = nexpr.expr(self).as(not null)
                if mtype != null then
                        mtype = self.anchor(mtype)
                        res = self.autobox(res, mtype)
                end
                res = autoadapt(res, nexpr.mtype.as(not null))
                var implicit_cast_to = nexpr.implicit_cast_to
                if implicit_cast_to != null and not self.compiler.modelbuilder.toolcontext.opt_no_check_autocast.value then
                        var castres = self.type_test(res, implicit_cast_to, "auto")
                        self.add("if (!{castres}) \{")
                        self.add_abort("Cast failed")
                        self.add("\}")
                        res = autoadapt(res, implicit_cast_to)
                end
                self.current_node = old
                return res
        end

        # Alias for `self.expr(nexpr, self.bool_type)'
        fun expr_bool(nexpr: AExpr): RuntimeVariable do return expr(nexpr, bool_type)

        # Safely show a debug message on the current node and repeat the message in the C code as a comment
        fun debug(message: String)
        do
                var node = self.current_node
                if node == null then
                        print "?: {message}"
                else
                        node.debug(message)
                end
                self.add("/* DEBUG: {message} */")
        end
end

# A C function associated to a Nit method
# Because of customization, a given Nit method can be compiler more that once
abstract class AbstractRuntimeFunction

        type COMPILER: AbstractCompiler
        type VISITOR: AbstractCompilerVisitor

        # The associated Nit method
        var mmethoddef: MMethodDef

        # The mangled c name of the runtime_function
        # Subclasses should redefine `build_c_name` instead
        fun c_name: String
        do
                var res = self.c_name_cache
                if res != null then return res
                res = self.build_c_name
                self.c_name_cache = res
                return res
        end

        # Non cached version of `c_name`
        protected fun build_c_name: String is abstract

        protected var c_name_cache: nullable String writable = null

        # Implements a call of the runtime_function
        # May inline the body or generate a C function call
        fun call(v: VISITOR, arguments: Array[RuntimeVariable]): nullable RuntimeVariable is abstract

        # Generate the code for the RuntimeFunction
        # Warning: compile more than once compilation makes CC unhappy
        fun compile_to_c(compiler: COMPILER) is abstract
end

# A runtime variable hold a runtime value in C.
# Runtime variables are associated to Nit local variables and intermediate results in Nit expressions.
#
# The tricky point is that a single C variable can be associated to more than one RuntimeVariable because the static knowledge of the type of an expression can vary in the C code.
class RuntimeVariable
        # The name of the variable in the C code
        var name: String

        # The static type of the variable (as declard in C)
        var mtype: MType

        # The current casted type of the variable (as known in Nit)
        var mcasttype: MType writable

        # If the variable exaclty a mcasttype?
        # false (usual value) means that the variable is a mcasttype or a subtype.
        var is_exact: Bool writable = false

        init(name: String, mtype: MType, mcasttype: MType)
        do
                self.name = name
                self.mtype = mtype
                self.mcasttype = mcasttype
                assert not mtype.need_anchor
                assert not mcasttype.need_anchor
        end

        redef fun to_s do return name

        redef fun inspect
        do
                var exact_str
                if self.is_exact then
                        exact_str = " exact"
                else
                        exact_str = ""
                end
                var type_str
                if self.mtype == self.mcasttype then
                        type_str = "{mtype}{exact_str}"
                else
                        type_str = "{mtype}({mcasttype}{exact_str})"
                end
                return "<{name}:{type_str}>"
        end
end

# A frame correspond to a visited property in a GlobalCompilerVisitor
class Frame

        type VISITOR: AbstractCompilerVisitor

        # The associated visitor
        var visitor: VISITOR

        # The executed property.
        # A Method in case of a call, an attribute in case of a default initialization.
        var mpropdef: MPropDef

        # The static type of the receiver
        var receiver: MClassType

        # Arguments of the method (the first is the receiver)
        var arguments: Array[RuntimeVariable]

        # The runtime_variable associated to the return (in a function)
        var returnvar: nullable RuntimeVariable writable = null

        # The label at the end of the property
        var returnlabel: nullable String writable = null
end

redef class String
        # Mangle a string to be a unique valid C identifier
        fun to_cmangle: String
        do
                var res = new Buffer
                var underscore = false
                for c in self do
                        if (c >= 'a' and c <= 'z') or (c >='A' and c <= 'Z') then
                                res.add(c)
                                underscore = false
                                continue
                        end
                        if underscore then
                                res.append('_'.ascii.to_s)
                                res.add('d')
                        end
                        if c >= '0' and c <= '9' then
                                res.add(c)
                                underscore = false
                        else if c == '_' then
                                res.add(c)
                                underscore = true
                        else
                                res.add('_')
                                res.append(c.ascii.to_s)
                                res.add('d')
                                underscore = false
                        end
                end
                return res.to_s
        end

        # Escape " \ ' and non printable characters for literal C strings or characters
        fun escape_to_c: String
        do
                var b = new Buffer
                for c in self do
                        if c == '\n' then
                                b.append("\\n")
                        else if c == '\0' then
                                b.append("\\0")
                        else if c == '"' then
                                b.append("\\\"")
                        else if c == '\'' then
                                b.append("\\\'")
                        else if c == '\\' then
                                b.append("\\\\")
                        else if c.ascii < 32 then
                                b.append("\\{c.ascii.to_base(8, false)}")
                        else
                                b.add(c)
                        end
                end
                return b.to_s
        end
end

redef class MType
        # Return the C type associated to a given Nit static type
        fun ctype: String do return "val*"

        fun ctypename: String do return "val"

        # Return the name of the C structure associated to a Nit live type
        fun c_name: String is abstract
        protected var c_name_cache: nullable String protected writable
end

redef class MClassType
        redef fun c_name
        do
                var res = self.c_name_cache
                if res != null then return res
                res = "{mclass.intro_mmodule.name.to_cmangle}__{mclass.name.to_cmangle}"
                self.c_name_cache = res
                return res
        end

        redef fun ctype: String
        do
                if mclass.name == "Int" then
                        return "long"
                else if mclass.name == "Bool" then
                        return "short int"
                else if mclass.name == "Char" then
                        return "char"
                else if mclass.name == "Float" then
                        return "double"
                else if mclass.name == "NativeString" then
                        return "char*"
                else if mclass.name == "NativeArray" then
                        return "val*"
                else if mclass.kind == extern_kind then
                        return "void*"
                else
                        return "val*"
                end
        end

        redef fun ctypename: String
        do
                if mclass.name == "Int" then
                        return "l"
                else if mclass.name == "Bool" then
                        return "s"
                else if mclass.name == "Char" then
                        return "c"
                else if mclass.name == "Float" then
                        return "d"
                else if mclass.name == "NativeString" then
                        return "str"
                else if mclass.name == "NativeArray" then
                        #return "{self.arguments.first.ctype}*"
                        return "val"
                else if mclass.kind == extern_kind then
                        return "ptr"
                else
                        return "val"
                end
        end
end

redef class MGenericType
        redef fun c_name
        do
                var res = self.c_name_cache
                if res != null then return res
                res = super
                for t in self.arguments do
                        res = res + t.c_name
                end
                self.c_name_cache = res
                return res
        end
end

redef class MParameterType
        redef fun c_name
        do
                var res = self.c_name_cache
                if res != null then return res
                res = "{self.mclass.c_name}_FT{self.rank}"
                self.c_name_cache = res
                return res
        end
end

redef class MVirtualType
        redef fun c_name
        do
                var res = self.c_name_cache
                if res != null then return res
                res = "{self.mproperty.intro.mclassdef.mclass.c_name}_VT{self.mproperty.name}"
                self.c_name_cache = res
                return res
        end
end

redef class MNullableType
        redef fun c_name
        do
                var res = self.c_name_cache
                if res != null then return res
                res = "nullable_{self.mtype.c_name}"
                self.c_name_cache = res
                return res
        end
end

redef class MClass
        # Return the name of the C structure associated to a Nit class
        fun c_name: String do
                var res = self.c_name_cache
                if res != null then return res
                res = "{intro_mmodule.name.to_cmangle}__{name.to_cmangle}"
                self.c_name_cache = res
                return res
        end
        private var c_name_cache: nullable String
end

redef class MProperty
        fun c_name: String do
                var res = self.c_name_cache
                if res != null then return res
                res = "{self.intro.c_name}"
                self.c_name_cache = res
                return res
        end
        private var c_name_cache: nullable String
end

redef class MPropDef
        type VISITOR: AbstractCompilerVisitor

        private var c_name_cache: nullable String

        # The mangled name associated to the property
        fun c_name: String
        do
                var res = self.c_name_cache
                if res != null then return res
                res = "{self.mclassdef.mmodule.name.to_cmangle}__{self.mclassdef.mclass.name.to_cmangle}__{self.mproperty.name.to_cmangle}"
                self.c_name_cache = res
                return res
        end
end

redef class MMethodDef
        # Can the body be inlined?
        fun can_inline(v: VISITOR): Bool
        do
                var modelbuilder = v.compiler.modelbuilder
                if modelbuilder.mpropdef2npropdef.has_key(self) then
                        var npropdef = modelbuilder.mpropdef2npropdef[self]
                        return npropdef.can_inline
                else if self.mproperty.name == "init" then
                        # Automatic free init is always inlined since it is empty or contains only attribtes assigments
                        return true
                else
                        abort
                end
        end

        # Inline the body in another visitor
        fun compile_inside_to_c(v: VISITOR, arguments: Array[RuntimeVariable]): nullable RuntimeVariable
        do
                var modelbuilder = v.compiler.modelbuilder
                if modelbuilder.mpropdef2npropdef.has_key(self) then
                        var npropdef = modelbuilder.mpropdef2npropdef[self]
                        var oldnode = v.current_node
                        v.current_node = npropdef
                        self.compile_parameter_check(v, arguments)
                        npropdef.compile_to_c(v, self, arguments)
                        v.current_node = oldnode
                else if self.mproperty.name == "init" then
                        var nclassdef = modelbuilder.mclassdef2nclassdef[self.mclassdef]
                        var oldnode = v.current_node
                        v.current_node = nclassdef
                        self.compile_parameter_check(v, arguments)
                        nclassdef.compile_to_c(v, self, arguments)
                        v.current_node = oldnode
                else
                        abort
                end
                return null
        end

        # Generate type checks in the C code to check covariant parameters
        fun compile_parameter_check(v: VISITOR, arguments: Array[RuntimeVariable])
        do
                if v.compiler.modelbuilder.toolcontext.opt_no_check_covariance.value then return

                for i in [0..msignature.arity[ do
                        # skip test for vararg since the array is instantiated with the correct polymorphic type
                        if msignature.vararg_rank == i then continue

                        # skip if the cast is not required
                        var origmtype =  self.mproperty.intro.msignature.mparameters[i].mtype
                        if not origmtype.need_anchor then continue

                        # get the parameter type
                        var mtype = self.msignature.mparameters[i].mtype

                        # generate the cast
                        # note that v decides if and how to implements the cast
                        v.add("/* Covariant cast for argument {i} ({self.msignature.mparameters[i].name}) {arguments[i+1].inspect} isa {mtype} */")
                        var cond = v.type_test(arguments[i+1], mtype, "covariance")
                        v.add("if (!{cond}) \{")
                        v.add_abort("Cast failed")
                        v.add("\}")
                end
        end
end

# Node visit

redef class APropdef
        fun compile_to_c(v: AbstractCompilerVisitor, mpropdef: MMethodDef, arguments: Array[RuntimeVariable])
        do
                v.add("printf(\"NOT YET IMPLEMENTED {class_name} {mpropdef} at {location.to_s}\\n\");")
                debug("Not yet implemented")
        end

        fun can_inline: Bool do return true
end

redef class AConcreteMethPropdef
        redef fun compile_to_c(v, mpropdef, arguments)
        do
                for i in [0..mpropdef.msignature.arity[ do
                        var variable = self.n_signature.n_params[i].variable.as(not null)
                        v.assign(v.variable(variable), arguments[i+1])
                end
                # Call the implicit super-init
                var auto_super_inits = self.auto_super_inits
                if auto_super_inits != null then
                        var selfarg = [arguments.first]
                        for auto_super_init in auto_super_inits do
                                if auto_super_init.intro.msignature.arity == 0 then
                                        v.send(auto_super_init, selfarg)
                                else
                                        v.send(auto_super_init, arguments)
                                end
                        end
                end
                v.stmt(self.n_block)
        end

        redef fun can_inline
        do
                if self.auto_super_inits != null then return false
                var nblock = self.n_block
                if nblock == null then return true
                if (mpropdef.mproperty.name == "==" or mpropdef.mproperty.name == "!=") and mpropdef.mclassdef.mclass.name == "Object" then return true
                if nblock isa ABlockExpr and nblock.n_expr.length == 0 then return true
                return false
        end
end

redef class AInternMethPropdef
        redef fun compile_to_c(v, mpropdef, arguments)
        do
                var pname = mpropdef.mproperty.name
                var cname = mpropdef.mclassdef.mclass.name
                var ret = mpropdef.msignature.return_mtype
                if ret != null then
                        ret = v.resolve_for(ret, arguments.first)
                end
                if pname != "==" and pname != "!=" then
                        v.adapt_signature(mpropdef, arguments)
                end
                if cname == "Int" then
                        if pname == "output" then
                                v.add("printf(\"%ld\\n\", {arguments.first});")
                                return
                        else if pname == "object_id" then
                                v.ret(arguments.first)
                                return
                        else if pname == "+" then
                                v.ret(v.new_expr("{arguments[0]} + {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "-" then
                                v.ret(v.new_expr("{arguments[0]} - {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "unary -" then
                                v.ret(v.new_expr("-{arguments[0]}", ret.as(not null)))
                                return
                        else if pname == "succ" then
                                v.ret(v.new_expr("{arguments[0]}+1", ret.as(not null)))
                                return
                        else if pname == "prec" then
                                v.ret(v.new_expr("{arguments[0]}-1", ret.as(not null)))
                                return
                        else if pname == "*" then
                                v.ret(v.new_expr("{arguments[0]} * {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "/" then
                                v.ret(v.new_expr("{arguments[0]} / {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "%" then
                                v.ret(v.new_expr("{arguments[0]} % {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "lshift" then
                                v.ret(v.new_expr("{arguments[0]} << {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "rshift" then
                                v.ret(v.new_expr("{arguments[0]} >> {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "==" then
                                v.ret(v.equal_test(arguments[0], arguments[1]))
                                return
                        else if pname == "!=" then
                                var res = v.equal_test(arguments[0], arguments[1])
                                v.ret(v.new_expr("!{res}", ret.as(not null)))
                                return
                        else if pname == "<" then
                                v.ret(v.new_expr("{arguments[0]} < {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == ">" then
                                v.ret(v.new_expr("{arguments[0]} > {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "<=" then
                                v.ret(v.new_expr("{arguments[0]} <= {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == ">=" then
                                v.ret(v.new_expr("{arguments[0]} >= {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "to_f" then
                                v.ret(v.new_expr("(double){arguments[0]}", ret.as(not null)))
                                return
                        else if pname == "ascii" then
                                v.ret(v.new_expr("{arguments[0]}", ret.as(not null)))
                                return
                        end
                else if cname == "Char" then
                        if pname == "output" then
                                v.add("printf(\"%c\", {arguments.first});")
                                return
                        else if pname == "object_id" then
                                v.ret(arguments.first)
                                return
                        else if pname == "+" then
                                v.ret(v.new_expr("{arguments[0]} + {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "-" then
                                v.ret(v.new_expr("{arguments[0]} - {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "==" then
                                v.ret(v.equal_test(arguments[0], arguments[1]))
                                return
                        else if pname == "!=" then
                                var res = v.equal_test(arguments[0], arguments[1])
                                v.ret(v.new_expr("!{res}", ret.as(not null)))
                                return
                        else if pname == "succ" then
                                v.ret(v.new_expr("{arguments[0]}+1", ret.as(not null)))
                                return
                        else if pname == "prec" then
                                v.ret(v.new_expr("{arguments[0]}-1", ret.as(not null)))
                                return
                        else if pname == "<" then
                                v.ret(v.new_expr("{arguments[0]} < {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == ">" then
                                v.ret(v.new_expr("{arguments[0]} > {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "<=" then
                                v.ret(v.new_expr("{arguments[0]} <= {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == ">=" then
                                v.ret(v.new_expr("{arguments[0]} >= {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "to_i" then
                                v.ret(v.new_expr("{arguments[0]}-'0'", ret.as(not null)))
                                return
                        else if pname == "ascii" then
                                v.ret(v.new_expr("(unsigned char){arguments[0]}", ret.as(not null)))
                                return
                        end
                else if cname == "Bool" then
                        if pname == "output" then
                                v.add("printf({arguments.first}?\"true\\n\":\"false\\n\");")
                                return
                        else if pname == "object_id" then
                                v.ret(arguments.first)
                                return
                        else if pname == "==" then
                                v.ret(v.equal_test(arguments[0], arguments[1]))
                                return
                        else if pname == "!=" then
                                var res = v.equal_test(arguments[0], arguments[1])
                                v.ret(v.new_expr("!{res}", ret.as(not null)))
                                return
                        end
                else if cname == "Float" then
                        if pname == "output" then
                                v.add("printf(\"%f\\n\", {arguments.first});")
                                return
                        else if pname == "object_id" then
                                v.ret(v.new_expr("(double){arguments.first}", ret.as(not null)))
                                return
                        else if pname == "+" then
                                v.ret(v.new_expr("{arguments[0]} + {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "-" then
                                v.ret(v.new_expr("{arguments[0]} - {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "unary -" then
                                v.ret(v.new_expr("-{arguments[0]}", ret.as(not null)))
                                return
                        else if pname == "succ" then
                                v.ret(v.new_expr("{arguments[0]}+1", ret.as(not null)))
                                return
                        else if pname == "prec" then
                                v.ret(v.new_expr("{arguments[0]}-1", ret.as(not null)))
                                return
                        else if pname == "*" then
                                v.ret(v.new_expr("{arguments[0]} * {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "/" then
                                v.ret(v.new_expr("{arguments[0]} / {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "==" then
                                v.ret(v.equal_test(arguments[0], arguments[1]))
                                return
                        else if pname == "!=" then
                                var res = v.equal_test(arguments[0], arguments[1])
                                v.ret(v.new_expr("!{res}", ret.as(not null)))
                                return
                        else if pname == "<" then
                                v.ret(v.new_expr("{arguments[0]} < {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == ">" then
                                v.ret(v.new_expr("{arguments[0]} > {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "<=" then
                                v.ret(v.new_expr("{arguments[0]} <= {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == ">=" then
                                v.ret(v.new_expr("{arguments[0]} >= {arguments[1]}", ret.as(not null)))
                                return
                        else if pname == "to_i" then
                                v.ret(v.new_expr("(long){arguments[0]}", ret.as(not null)))
                                return
                        end
                else if cname == "Char" then
                        if pname == "output" then
                                v.add("printf(\"%c\", {arguments.first});")
                                return
                        else if pname == "object_id" then
                                v.ret(arguments.first)
                                return
                        else if pname == "==" then
                                v.ret(v.equal_test(arguments[0], arguments[1]))
                                return
                        else if pname == "!=" then
                                var res = v.equal_test(arguments[0], arguments[1])
                                v.ret(v.new_expr("!{res}", ret.as(not null)))
                                return
                        else if pname == "ascii" then
                                v.ret(v.new_expr("{arguments[0]}", ret.as(not null)))
                                return
                        end
                else if cname == "NativeString" then
                        if pname == "[]" then
                                v.ret(v.new_expr("{arguments[0]}[{arguments[1]}]", ret.as(not null)))
                                return
                        else if pname == "[]=" then
                                v.add("{arguments[0]}[{arguments[1]}]={arguments[2]};")
                                return
                        else if pname == "copy_to" then
                                v.add("memcpy({arguments[1]}+{arguments[4]},{arguments[0]}+{arguments[3]},{arguments[2]});")
                                return
                        else if pname == "atoi" then
                                v.ret(v.new_expr("atoi({arguments[0]});", ret.as(not null)))
                                return
                        end
                else if cname == "NativeArray" then
                        v.native_array_def(pname, ret, arguments)
                        return
                end
                if pname == "exit" then
                        v.add("exit({arguments[1]});")
                        return
                else if pname == "sys" then
                        v.ret(v.new_expr("glob_sys", ret.as(not null)))
                        return
                else if pname == "calloc_string" then
                        v.ret(v.new_expr("(char*)GC_MALLOC_ATOMIC({arguments[1]})", ret.as(not null)))
                        return
                else if pname == "calloc_array" then
                        v.calloc_array(ret.as(not null), arguments)
                        return
                else if pname == "object_id" then
                        v.ret(v.new_expr("(long){arguments.first}", ret.as(not null)))
                        return
                else if pname == "is_same_type" then
                        v.ret(v.is_same_type_test(arguments[0], arguments[1]))
                        return
                else if pname == "output_class_name" then
                        var nat = v.class_name_string(arguments.first)
                        v.add("printf(\"%s\\n\", {nat});")
                        return
                else if pname == "native_class_name" then
                        var nat = v.class_name_string(arguments.first)
                        v.ret(v.new_expr("(char*){nat}", ret.as(not null)))
                        return
                else if pname == "force_garbage_collection" then
                        v.add("GC_gcollect();")
                        return
                end
                v.add("printf(\"NOT YET IMPLEMENTED {class_name}:{mpropdef} at {location.to_s}\\n\");")
                debug("Not implemented {mpropdef}")
        end
end

redef class AExternMethPropdef
        redef fun compile_to_c(v, mpropdef, arguments)
        do
                var externname
                var nextern = self.n_extern
                if nextern == null then
                        v.add("fprintf(stderr, \"NOT YET IMPLEMENTED nitni for {mpropdef} at {location.to_s}\\n\");")
                        v.add("exit(1);")
                        return
                end
                externname = nextern.text.substring(1, nextern.text.length-2)
                if location.file != null then
                        var file = location.file.filename
                        v.compiler.add_extern(file)
                end
                var res: nullable RuntimeVariable = null
                var ret = mpropdef.msignature.return_mtype
                if ret != null then
                        ret = v.resolve_for(ret, arguments.first)
                        res = v.new_var(ret)
                end
                v.adapt_signature(mpropdef, arguments)

                if res == null then
                        v.add("{externname}({arguments.join(", ")});")
                else
                        v.add("{res} = {externname}({arguments.join(", ")});")
                        v.ret(res)
                end
        end
end

redef class AExternInitPropdef
        redef fun compile_to_c(v, mpropdef, arguments)
        do
                var externname
                var nextern = self.n_extern
                if nextern == null then
                        debug("{mpropdef} need extern name")
                        return
                end
                externname = nextern.text.substring(1, nextern.text.length-2)
                if location.file != null then
                        var file = location.file.filename
                        v.compiler.add_extern(file)
                end
                v.adapt_signature(mpropdef, arguments)
                var ret = arguments.first.mtype
                var res = v.new_var(ret)

                arguments.shift

                v.add("{res} = {externname}({arguments.join(", ")});")
                v.ret(res)
        end
end

redef class AAttrPropdef
        redef fun compile_to_c(v, mpropdef, arguments)
        do
                if arguments.length == 1 then
                        var res = v.read_attribute(self.mpropdef.mproperty, arguments.first)
                        v.assign(v.frame.returnvar.as(not null), res)
                else
                        v.write_attribute(self.mpropdef.mproperty, arguments.first, arguments[1])
                end
        end

        fun init_expr(v: AbstractCompilerVisitor, recv: RuntimeVariable)
        do
                var nexpr = self.n_expr
                if nexpr != null then
                        var oldnode = v.current_node
                        v.current_node = self
                        var old_frame = v.frame
                        var frame = new Frame(v, self.mpropdef.as(not null), recv.mtype.as(MClassType), [recv])
                        v.frame = frame
                        var value = v.expr(nexpr, self.mpropdef.static_mtype)
                        v.write_attribute(self.mpropdef.mproperty, recv, value)
                        v.frame = old_frame
                        v.current_node = oldnode
                end
        end

        fun check_expr(v: AbstractCompilerVisitor, recv: RuntimeVariable)
        do
                var nexpr = self.n_expr
                if nexpr != null then return

                var oldnode = v.current_node
                v.current_node = self
                var old_frame = v.frame
                var frame = new Frame(v, self.mpropdef.as(not null), recv.mtype.as(MClassType), [recv])
                v.frame = frame
                # Force read to check the initialization
                v.read_attribute(self.mpropdef.mproperty, recv)
                v.frame = old_frame
                v.current_node = oldnode
        end
end

redef class AClassdef
        private fun compile_to_c(v: AbstractCompilerVisitor, mpropdef: MMethodDef, arguments: Array[RuntimeVariable])
        do
                if mpropdef == self.mfree_init then
                        var super_inits = self.super_inits
                        if super_inits != null then
                                assert arguments.length == 1
                                for su in super_inits do
                                        v.send(su, arguments)
                                end
                                return
                        end
                        var recv = arguments.first
                        var i = 1
                        # Collect undefined attributes
                        for npropdef in self.n_propdefs do
                                if npropdef isa AAttrPropdef and npropdef.n_expr == null then
                                        v.write_attribute(npropdef.mpropdef.mproperty, recv, arguments[i])
                                        i += 1
                                end
                        end
                else
                        abort
                end
        end
end

redef class ADeferredMethPropdef
        redef fun compile_to_c(v, mpropdef, arguments) do v.add_abort("Deferred method called")
        redef fun can_inline do return true
end

redef class AExpr
        # Try to compile self as an expression
        # Do not call this method directly, use `v.expr' instead
        private fun expr(v: AbstractCompilerVisitor): nullable RuntimeVariable
        do
                v.add("printf(\"NOT YET IMPLEMENTED {class_name}:{location.to_s}\\n\");")
                var mtype = self.mtype
                if mtype == null then
                        return null
                else
                        var res = v.new_var(mtype)
                        v.add("/* {res} = NOT YET {class_name} */")
                        return res
                end
        end

        # Try to compile self as a statement
        # Do not call this method directly, use `v.stmt' instead
        private fun stmt(v: AbstractCompilerVisitor)
        do
                var res = expr(v)
                if res != null then v.add("{res};")
        end
end

redef class ABlockExpr
        redef fun stmt(v)
        do
                for e in self.n_expr do v.stmt(e)
        end
end

redef class AVardeclExpr
        redef fun stmt(v)
        do
                var variable = self.variable.as(not null)
                var ne = self.n_expr
                if ne != null then
                        var i = v.expr(ne, variable.declared_type)
                        v.assign(v.variable(variable), i)
                end
        end
end

redef class AVarExpr
        redef fun expr(v)
        do
                var res = v.variable(self.variable.as(not null))
                var mtype = self.mtype.as(not null)
                return v.autoadapt(res, mtype)
        end
end

redef class AVarAssignExpr
        redef fun stmt(v)
        do
                var variable = self.variable.as(not null)
                var i = v.expr(self.n_value, variable.declared_type)
                v.assign(v.variable(variable), i)
        end
end

redef class AVarReassignExpr
        redef fun stmt(v)
        do
                var variable = self.variable.as(not null)
                var vari = v.variable(variable)
                var value = v.expr(self.n_value, variable.declared_type)
                var res = v.compile_callsite(self.reassign_callsite.as(not null), [vari, value])
                assert res != null
                v.assign(v.variable(variable), res)
        end
end

redef class ASelfExpr
        redef fun expr(v) do return v.frame.arguments.first
end

redef class AContinueExpr
        redef fun stmt(v) do v.add("goto CONTINUE_{v.escapemark_name(self.escapemark)};")
end

redef class ABreakExpr
        redef fun stmt(v) do v.add("goto BREAK_{v.escapemark_name(self.escapemark)};")
end

redef class AReturnExpr
        redef fun stmt(v)
        do
                var nexpr = self.n_expr
                if nexpr != null then
                        var returnvar = v.frame.returnvar.as(not null)
                        var i = v.expr(nexpr, returnvar.mtype)
                        v.assign(returnvar, i)
                end
                v.add("goto {v.frame.returnlabel.as(not null)};")
        end
end

redef class AAbortExpr
        redef fun stmt(v) do v.add_abort("Aborted")
end

redef class AIfExpr
        redef fun stmt(v)
        do
                var cond = v.expr_bool(self.n_expr)
                v.add("if ({cond})\{")
                v.stmt(self.n_then)
                v.add("\} else \{")
                v.stmt(self.n_else)
                v.add("\}")
        end
end

redef class AIfexprExpr
        redef fun expr(v)
        do
                var res = v.new_var(self.mtype.as(not null))
                var cond = v.expr_bool(self.n_expr)
                v.add("if ({cond})\{")
                v.assign(res, v.expr(self.n_then, null))
                v.add("\} else \{")
                v.assign(res, v.expr(self.n_else, null))
                v.add("\}")
                return res
        end
end

redef class ADoExpr
        redef fun stmt(v)
        do
                v.stmt(self.n_block)
                var escapemark = self.escapemark
                if escapemark != null then
                        v.add("BREAK_{v.escapemark_name(escapemark)}: (void)0;")
                end
        end
end

redef class AWhileExpr
        redef fun stmt(v)
        do
                v.add("for(;;) \{")
                var cond = v.expr_bool(self.n_expr)
                v.add("if (!{cond}) break;")
                v.stmt(self.n_block)
                v.add("CONTINUE_{v.escapemark_name(escapemark)}: (void)0;")
                v.add("\}")
                v.add("BREAK_{v.escapemark_name(escapemark)}: (void)0;")
        end
end

redef class ALoopExpr
        redef fun stmt(v)
        do
                v.add("for(;;) \{")
                v.stmt(self.n_block)
                v.add("CONTINUE_{v.escapemark_name(escapemark)}: (void)0;")
                v.add("\}")
                v.add("BREAK_{v.escapemark_name(escapemark)}: (void)0;")
        end
end

redef class AForExpr
        redef fun stmt(v)
        do
                # Shortcut on explicit range
                # Avoid the instantiation of the range and the iterator
                var nexpr = self.n_expr
                if self.variables.length == 1 and nexpr isa AOrangeExpr and not v.compiler.modelbuilder.toolcontext.opt_no_shortcut_range.value then
                        var from = v.expr(nexpr.n_expr, null)
                        var to = v.expr(nexpr.n_expr2, null)
                        var variable = v.variable(variables.first)

                        v.assign(variable, from)
                        v.add("for(;;) \{ /* shortcut range */")

                        var ok = v.send(v.get_property("<", variable.mtype), [variable, to])
                        assert ok != null
                        v.add("if(!{ok}) break;")

                        v.stmt(self.n_block)

                        v.add("CONTINUE_{v.escapemark_name(escapemark)}: (void)0;")
                        var succ = v.send(v.get_property("succ", variable.mtype), [variable])
                        assert succ != null
                        v.assign(variable, succ)
                        v.add("\}")
                        v.add("BREAK_{v.escapemark_name(escapemark)}: (void)0;")
                        return
                end

                var cl = v.expr(self.n_expr, null)
                var it_meth = self.method_iterator
                assert it_meth != null
                var it = v.send(it_meth, [cl])
                assert it != null
                v.add("for(;;) \{")
                var isok_meth = self.method_is_ok
                assert isok_meth != null
                var ok = v.send(isok_meth, [it])
                assert ok != null
                v.add("if(!{ok}) break;")
                if self.variables.length == 1 then
                        var item_meth = self.method_item
                        assert item_meth != null
                        var i = v.send(item_meth, [it])
                        assert i != null
                        v.assign(v.variable(variables.first), i)
                else if self.variables.length == 2 then
                        var key_meth = self.method_key
                        assert key_meth != null
                        var i = v.send(key_meth, [it])
                        assert i != null
                        v.assign(v.variable(variables[0]), i)
                        var item_meth = self.method_item
                        assert item_meth != null
                        i = v.send(item_meth, [it])
                        assert i != null
                        v.assign(v.variable(variables[1]), i)
                else
                        abort
                end
                v.stmt(self.n_block)
                v.add("CONTINUE_{v.escapemark_name(escapemark)}: (void)0;")
                var next_meth = self.method_next
                assert next_meth != null
                v.send(next_meth, [it])
                v.add("\}")
                v.add("BREAK_{v.escapemark_name(escapemark)}: (void)0;")
        end
end

redef class AAssertExpr
        redef fun stmt(v)
        do
                if v.compiler.modelbuilder.toolcontext.opt_no_check_assert.value then return

                var cond = v.expr_bool(self.n_expr)
                v.add("if (!{cond}) \{")
                v.stmt(self.n_else)
                var nid = self.n_id
                if nid != null then
                        v.add_abort("Assert '{nid.text}' failed")
                else
                        v.add_abort("Assert failed")
                end
                v.add("\}")
        end
end

redef class AOrExpr
        redef fun expr(v)
        do
                var res = v.new_var(self.mtype.as(not null))
                var i1 = v.expr_bool(self.n_expr)
                v.add("if ({i1}) \{")
                v.add("{res} = 1;")
                v.add("\} else \{")
                var i2 = v.expr_bool(self.n_expr2)
                v.add("{res} = {i2};")
                v.add("\}")
                return res
        end
end

redef class AAndExpr
        redef fun expr(v)
        do
                var res = v.new_var(self.mtype.as(not null))
                var i1 = v.expr_bool(self.n_expr)
                v.add("if (!{i1}) \{")
                v.add("{res} = 0;")
                v.add("\} else \{")
                var i2 = v.expr_bool(self.n_expr2)
                v.add("{res} = {i2};")
                v.add("\}")
                return res
        end
end

redef class ANotExpr
        redef fun expr(v)
        do
                var cond = v.expr_bool(self.n_expr)
                return v.new_expr("!{cond}", self.mtype.as(not null))
        end
end

redef class AOrElseExpr
        redef fun expr(v)
        do
                var res = v.new_var(self.mtype.as(not null))
                var i1 = v.expr(self.n_expr, null)
                v.add("if ({i1}!=NULL) \{")
                v.assign(res, i1)
                v.add("\} else \{")
                var i2 = v.expr(self.n_expr2, null)
                v.assign(res, i2)
                v.add("\}")
                return res
        end
end

redef class AEeExpr
        redef fun expr(v)
        do
                var value1 = v.expr(self.n_expr, null)
                var value2 = v.expr(self.n_expr2, null)
                return v.equal_test(value1, value2)
        end
end

redef class AIntExpr
        redef fun expr(v) do return v.new_expr("{self.n_number.text}", self.mtype.as(not null))
end

redef class AFloatExpr
        redef fun expr(v) do return v.new_expr("{self.n_float.text}", self.mtype.as(not null))
end

redef class ACharExpr
        redef fun expr(v) do return v.new_expr("{self.n_char.text}", self.mtype.as(not null))
end

redef class AArrayExpr
        redef fun expr(v)
        do
                var mtype = self.mtype.as(MClassType).arguments.first
                var array = new Array[RuntimeVariable]
                for nexpr in self.n_exprs.n_exprs do
                        var i = v.expr(nexpr, mtype)
                        array.add(i)
                end
                return v.array_instance(array, mtype)
        end
end

redef class AStringFormExpr
        redef fun expr(v) do return v.string_instance(self.value.as(not null))
end

redef class ASuperstringExpr
        redef fun expr(v)
        do
                var array = new Array[RuntimeVariable]
                for ne in self.n_exprs do
                        if ne isa AStringFormExpr and ne.value == "" then continue # skip empty sub-strings
                        var i = v.expr(ne, null)
                        array.add(i)
                end
                var a = v.array_instance(array, v.object_type)
                var res = v.send(v.get_property("to_s", a.mtype), [a])
                return res
        end
end

redef class ACrangeExpr
        redef fun expr(v)
        do
                var i1 = v.expr(self.n_expr, null)
                var i2 = v.expr(self.n_expr2, null)
                var mtype = self.mtype.as(MClassType)
                var res = v.init_instance(mtype)
                var it = v.send(v.get_property("init", res.mtype), [res, i1, i2])
                v.check_init_instance(res, mtype)
                return res
        end
end

redef class AOrangeExpr
        redef fun expr(v)
        do
                var i1 = v.expr(self.n_expr, null)
                var i2 = v.expr(self.n_expr2, null)
                var mtype = self.mtype.as(MClassType)
                var res = v.init_instance(mtype)
                var it = v.send(v.get_property("without_last", res.mtype), [res, i1, i2])
                v.check_init_instance(res, mtype)
                return res
        end
end

redef class ATrueExpr
        redef fun expr(v) do return v.new_expr("1", self.mtype.as(not null))
end

redef class AFalseExpr
        redef fun expr(v) do return v.new_expr("0", self.mtype.as(not null))
end

redef class ANullExpr
        redef fun expr(v) do return v.new_expr("NULL", self.mtype.as(not null))
end

redef class AIsaExpr
        redef fun expr(v)
        do
                var i = v.expr(self.n_expr, null)
                return v.type_test(i, self.cast_type.as(not null), "isa")
        end
end

redef class AAsCastExpr
        redef fun expr(v)
        do
                var i = v.expr(self.n_expr, null)
                if v.compiler.modelbuilder.toolcontext.opt_no_check_assert.value then return i

                var cond = v.type_test(i, self.mtype.as(not null), "as")
                v.add("if (!{cond}) \{")
                v.add_abort("Cast failed")
                v.add("\}")
                return i
        end
end

redef class AAsNotnullExpr
        redef fun expr(v)
        do
                var i = v.expr(self.n_expr, null)
                if v.compiler.modelbuilder.toolcontext.opt_no_check_assert.value then return i

                v.add("if ({i} == NULL) \{")
                v.add_abort("Cast failed")
                v.add("\}")
                return i
        end
end

redef class AParExpr
        redef fun expr(v) do return v.expr(self.n_expr, null)
end

redef class AOnceExpr
        redef fun expr(v)
        do
                var mtype = self.mtype.as(not null)
                var name = v.get_name("varonce")
                var guard = v.get_name(name + "_guard")
                v.add_decl("static {mtype.ctype} {name};")
                v.add_decl("static int {guard};")
                var res = v.new_var(mtype)
                v.add("if ({guard}) \{")
                v.add("{res} = {name};")
                v.add("\} else \{")
                var i = v.expr(self.n_expr, mtype)
                v.add("{res} = {i};")
                v.add("{name} = {res};")
                v.add("{guard} = 1;")
                v.add("\}")
                return res
        end
end

redef class ASendExpr
        redef fun expr(v)
        do
                var recv = v.expr(self.n_expr, null)
                var args = [recv]
                for a in self.raw_arguments.as(not null) do
                        args.add(v.expr(a, null))
                end
                return v.compile_callsite(self.callsite.as(not null), args)
        end
end

redef class ASendReassignFormExpr
        redef fun stmt(v)
        do
                var recv = v.expr(self.n_expr, null)
                var args = [recv]
                for a in self.raw_arguments.as(not null) do
                        args.add(v.expr(a, null))
                end
                var value = v.expr(self.n_value, null)

                var left = v.compile_callsite(self.callsite.as(not null), args)
                assert left != null

                var res = v.compile_callsite(self.reassign_callsite.as(not null), [left, value])
                assert res != null

                args.add(res)
                v.compile_callsite(self.write_callsite.as(not null), args)
        end
end

redef class ASuperExpr
        redef fun expr(v)
        do
                var recv = v.frame.arguments.first
                var args = [recv]
                for a in self.n_args.n_exprs do
                        args.add(v.expr(a, null))
                end
                if args.length == 1 then
                        args = v.frame.arguments
                end

                var mproperty = self.mproperty
                if mproperty != null then
                        if mproperty.intro.msignature.arity == 0 then
                                args = [recv]
                        end
                        # Super init call
                        var res = v.send(mproperty, args)
                        return res
                end

                # stantard call-next-method
                return v.supercall(v.frame.mpropdef.as(MMethodDef), recv.mtype.as(MClassType), args)
        end
end

redef class ANewExpr
        redef fun expr(v)
        do
                var mtype = self.mtype.as(MClassType)
                var recv
                var ctype = mtype.ctype
                if ctype == "val*" then
                        recv = v.init_instance(mtype)
                else if ctype == "void*" then
                        recv = v.new_expr("NULL/*special!*/", mtype)
                else
                        debug("cannot new {mtype}")
                        abort
                end
                var args = [recv]
                for a in self.n_args.n_exprs do
                        args.add(v.expr(a, null))
                end
                var res2 = v.compile_callsite(self.callsite.as(not null), args)
                if res2 != null then
                        #self.debug("got {res2} from {mproperty}. drop {recv}")
                        return res2
                end
                v.check_init_instance(recv, mtype)
                return recv
        end
end

redef class AAttrExpr
        redef fun expr(v)
        do
                var recv = v.expr(self.n_expr, null)
                var mproperty = self.mproperty.as(not null)
                return v.read_attribute(mproperty, recv)
        end
end

redef class AAttrAssignExpr
        redef fun stmt(v)
        do
                var recv = v.expr(self.n_expr, null)
                var i = v.expr(self.n_value, null)
                var mproperty = self.mproperty.as(not null)
                v.write_attribute(mproperty, recv, i)
        end
end

redef class AAttrReassignExpr
        redef fun stmt(v)
        do
                var recv = v.expr(self.n_expr, null)
                var value = v.expr(self.n_value, null)
                var mproperty = self.mproperty.as(not null)
                var attr = v.read_attribute(mproperty, recv)
                var res = v.compile_callsite(self.reassign_callsite.as(not null), [attr, value])
                assert res != null
                v.write_attribute(mproperty, recv, res)
        end
end

redef class AIssetAttrExpr
        redef fun expr(v)
        do
                var recv = v.expr(self.n_expr, null)
                var mproperty = self.mproperty.as(not null)
                return v.isset_attribute(mproperty, recv)
        end
end

redef class ADebugTypeExpr
        redef fun stmt(v)
        do
                # do nothing
        end
end

# Utils

redef class HashSet[E]
        init from(elements: Collection[E]) do
                init
                self.add_all(elements)
        end
end

redef class Array[E]
        init from(elements: Collection[E]) do
                init
                self.add_all(elements)
        end

        # Return a new Array with the elements only contened in 'self' and not in 'o'
        fun -(o: Array[E]): Array[E] do
                var res = new Array[E]
                for e in self do if not o.has(e) then res.add(e)
                return res
        end
end

redef class MModule

        # Return a linearization of a set of mtypes
        fun linearize_mtypes(mtypes: Set[MType]): Array[MType] do
                var lin = new Array[MType].from(mtypes)
                var sorter = new TypeSorter(self)
                sorter.sort(lin)
                return lin
        end

        # Return a reverse linearization of a set of mtypes
        fun reverse_linearize_mtypes(mtypes: Set[MType]): Array[MType] do
                var lin = new Array[MType].from(mtypes)
                var sorter = new ReverseTypeSorter(self)
                sorter.sort(lin)
                return lin
        end

        # Return super types of a `mtype` in `self`
        fun super_mtypes(mtype: MType, mtypes: Set[MType]): Set[MType] do
                if not self.super_mtypes_cache.has_key(mtype) then
                        var supers = new HashSet[MType]
                        for otype in mtypes do
                                if otype == mtype then continue
                                if mtype.is_subtype(self, null, otype) then
                                        supers.add(otype)
                                end
                        end
                        self.super_mtypes_cache[mtype] = supers
                end
                return self.super_mtypes_cache[mtype]
        end

        private var super_mtypes_cache: Map[MType, Set[MType]] = new HashMap[MType, Set[MType]]

        # Return all sub mtypes (directs and indirects) of a `mtype` in `self`
        fun sub_mtypes(mtype: MType, mtypes: Set[MType]): Set[MType] do
                if not self.sub_mtypes_cache.has_key(mtype) then
                        var subs = new HashSet[MType]
                        for otype in mtypes do
                                if otype == mtype then continue
                                if otype.is_subtype(self, null, mtype) then
                                        subs.add(otype)
                                end
                        end
                        self.sub_mtypes_cache[mtype] = subs
                end
                return self.sub_mtypes_cache[mtype]
        end

        private var sub_mtypes_cache: Map[MType, Set[MType]] = new HashMap[MType, Set[MType]]

        # Return a linearization of a set of mclasses
        fun linearize_mclasses_2(mclasses: Set[MClass]): Array[MClass] do
                var lin = new Array[MClass].from(mclasses)
                var sorter = new ClassSorter(self)
                sorter.sort(lin)
                return lin
        end

        # Return a reverse linearization of a set of mtypes
        fun reverse_linearize_mclasses(mclasses: Set[MClass]): Array[MClass] do
                var lin = new Array[MClass].from(mclasses)
                var sorter = new ReverseClassSorter(self)
                sorter.sort(lin)
                return lin
        end

        # Return all super mclasses (directs and indirects) of a `mclass` in `self`
        fun super_mclasses(mclass: MClass): Set[MClass] do
                if not self.super_mclasses_cache.has_key(mclass) then
                        var supers = new HashSet[MClass]
                        if self.flatten_mclass_hierarchy.has(mclass) then
                                for sup in self.flatten_mclass_hierarchy[mclass].greaters do
                                        if sup == mclass then continue
                                        supers.add(sup)
                                end
                        end
                        self.super_mclasses_cache[mclass] = supers
                end
                return self.super_mclasses_cache[mclass]
        end

        private var super_mclasses_cache: Map[MClass, Set[MClass]] = new HashMap[MClass, Set[MClass]]

        # Return all parents of a `mclass` in `self`
        fun parent_mclasses(mclass: MClass): Set[MClass] do
                if not self.parent_mclasses_cache.has_key(mclass) then
                        var parents = new HashSet[MClass]
                        if self.flatten_mclass_hierarchy.has(mclass) then
                                for sup in self.flatten_mclass_hierarchy[mclass].direct_greaters do
                                        if sup == mclass then continue
                                        parents.add(sup)
                                end
                        end
                        self.parent_mclasses_cache[mclass] = parents
                end
                return self.parent_mclasses_cache[mclass]
        end

        private var parent_mclasses_cache: Map[MClass, Set[MClass]] = new HashMap[MClass, Set[MClass]]

        # Return all sub mclasses (directs and indirects) of a `mclass` in `self`
        fun sub_mclasses(mclass: MClass): Set[MClass] do
                if not self.sub_mclasses_cache.has_key(mclass) then
                        var subs = new HashSet[MClass]
                        if self.flatten_mclass_hierarchy.has(mclass) then
                                for sub in self.flatten_mclass_hierarchy[mclass].smallers do
                                        if sub == mclass then continue
                                        subs.add(sub)
                                end
                        end
                        self.sub_mclasses_cache[mclass] = subs
                end
                return self.sub_mclasses_cache[mclass]
        end

        private var sub_mclasses_cache: Map[MClass, Set[MClass]] = new HashMap[MClass, Set[MClass]]

        # All 'mproperties' associated to all 'mclassdefs' of `mclass`
        fun properties(mclass: MClass): Set[MProperty] do
                if not self.properties_cache.has_key(mclass) then
                        var properties = new HashSet[MProperty]
                        var parents = self.super_mclasses(mclass)
                        for parent in parents do
                                properties.add_all(self.properties(parent))
                        end

                        for mclassdef in mclass.mclassdefs do
                                for mpropdef in mclassdef.mpropdefs do
                                        properties.add(mpropdef.mproperty)
                                end
                        end
                        self.properties_cache[mclass] = properties
                end
                return properties_cache[mclass]
        end

        private var properties_cache: Map[MClass, Set[MProperty]] = new HashMap[MClass, Set[MProperty]]
end

# A sorter for linearize list of types
private class TypeSorter
        super AbstractSorter[MType]

        private var mmodule: MModule

        init(mmodule: MModule) do self.mmodule = mmodule

        redef fun compare(a, b) do
                if a == b then
                        return 0
                else if a.is_subtype(self.mmodule, null, b) then
                        return -1
                end
                return 1
        end
end

# A sorter for reverse linearization
private class ReverseTypeSorter
        super TypeSorter

        init(mmodule: MModule) do end

        redef fun compare(a, b) do
                if a == b then
                        return 0
                else if a.is_subtype(self.mmodule, null, b) then
                        return 1
                end
                return -1
        end
end

# A sorter for linearize list of classes
private class ClassSorter
        super AbstractSorter[MClass]

        var mmodule: MModule

        redef fun compare(a, b) do
                if a == b then
                        return 0
                else if self.mmodule.flatten_mclass_hierarchy.has(a) and self.mmodule.flatten_mclass_hierarchy[a].greaters.has(b) then
                        return -1
                end
                return 1
        end
end

# A sorter for reverse linearization
private class ReverseClassSorter
        super AbstractSorter[MClass]

        var mmodule: MModule

        redef fun compare(a, b) do
                if a == b then
                        return 0
                else if self.mmodule.flatten_mclass_hierarchy.has(a) and self.mmodule.flatten_mclass_hierarchy[a].greaters.has(b) then
                        return 1
                end
                return -1
        end
end