[nit.git] / contrib / jwrapper / src / code_generator.nit

# This file is part of NIT (http://www.nitlanguage.org).
#
# Copyright 2014 Frédéric Vachon <fredvac@gmail.com>
# Copyright 2015 Alexis Laferrière <alexis.laf@xymus.net>
#
# 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.

# Services to generate extern class `in "Java"`
module code_generator

intrude import model

class CodeGenerator

        # Path to the output file
        var file_name: String

        # Model of Java class being wrapped
        var model: JavaModel

        # Comment out methods with unknown (unwrapped) types
        var comment_unknown_types: Bool

        # Generate stub classes for unknown types used in the generated module
        var stub_for_unknown_types: Bool

        # Output file
        var file_out: Writer = new FileWriter.open(file_name) is lazy, writable

        # Name of the Nit module to generate
        var module_name: nullable String is lazy do
                if file_name.file_extension == "nit" then
                        # Output file ends with .nit, we expect it to be a valid name
                        return file_name.basename(".nit")
                else return null
        end

        # Generate the Nit module into `file_out`
        fun generate
        do
                # License
                file_out.write license

                # Module declaration
                var module_name = module_name
                if module_name != null then file_out.write "module {module_name}\n"
                file_out.write "\n"

                # All importations
                var imports = new HashSet[String]
                imports.add "import java\n"
                for key, jclass in model.classes do
                        for import_ in jclass.imports do imports.add "import android::{import_}\n"
                end
                file_out.write imports.join("\n")
                file_out.write "\n"

                for key, jclass in model.classes do
                        # Skip anonymous classes
                        if jclass.class_type.is_anonymous then continue

                        generate_class_header(jclass.class_type)

                        for id, signatures in jclass.methods do
                                for signature in signatures do if not signature.is_static then
                                        generate_method(jclass, id, id, signature.return_type, signature.params)
                                        file_out.write "\n"
                                end
                        end

                        # Constructors
                        for constructor in jclass.constructors do
                                var complex = jclass.constructors.length != 1 and constructor.params.not_empty
                                var base_name = if complex then "from" else ""
                                var name = jclass.nit_name_for(base_name, constructor.params, complex, false)

                                generate_constructor(jclass, constructor, name)
                        end

                        # Attributes
                        for id, attribute in jclass.attributes do if not attribute.is_static then
                                generate_getter_setter(jclass, id, attribute)
                        end

                        # JNI services
                        generate_jni_services jclass.class_type

                        # Close the class
                        file_out.write "end\n\n"

                        # Static functions as top-level methods
                        var static_functions_prefix = jclass.class_type.extern_name.to_snake_case
                        for id, signatures in jclass.methods do
                                for signature in signatures do if signature.is_static then
                                        var nit_id = static_functions_prefix + "_" + id
                                        generate_method(jclass, id, nit_id, signature.return_type, signature.params, is_static=true)
                                        file_out.write "\n"
                                end
                        end

                        # Static attributes as top-level getters and setters
                        for id, attribute in jclass.attributes do if attribute.is_static then
                                generate_getter_setter(jclass, id, attribute)
                        end

                        # Primitive arrays
                        for d in [1..opt_arrays.value] do
                                generate_primitive_array(jclass, d)
                        end
                end

                if stub_for_unknown_types then
                        for jtype, nit_type in model.unknown_types do
                                generate_unknown_class_header(jtype)
                                file_out.write "\n"
                        end
                end
        end

        # License for the header of the generated Nit module
        var license = """
# This file is part of NIT (http://www.nitlanguage.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.

# This code has been generated using `jwrapper`
""" is writable

        private fun generate_class_header(jtype: JavaType)
        do
                var nit_type = model.java_to_nit_type(jtype)
                file_out.write "# Java class: {jtype}\n"
                file_out.write "extern class {nit_type} in \"Java\" `\{ {jtype.extern_equivalent} `\}\n"
                file_out.write "\tsuper JavaObject\n\n"
        end

        private fun generate_unknown_class_header(jtype: JavaType)
        do
                var nit_type = jtype.extern_name

                file_out.write "extern class {nit_type} in \"Java\" `\{ {jtype.extern_equivalent} `\}\n"
                file_out.write "\tsuper JavaObject\n\nend\n"
        end

        private fun generate_method(java_class: JavaClass, java_method_id, method_id: String,
                java_return_type: JavaType, java_params: Array[JavaType], is_static: nullable Bool)
        do
                var java_args = new Array[String]
                var nit_params = new Array[String]
                var nit_id = "arg"
                var nit_id_no = 0
                var c = ""

                # Parameters
                for jparam in java_params do
                        var nit_type = model.java_to_nit_type(jparam)

                        if not nit_type.is_known and comment_unknown_types then c = "#"
                        if jparam.is_vararg then c = "#"

                        java_args.add "{jparam.param_cast}{nit_id}{nit_id_no}"
                        nit_params.add "{nit_id}{nit_id_no}: {nit_type}"

                        nit_id_no += 1
                end

                # Method identifier
                method_id = method_id.to_nit_method_name
                method_id = java_class.nit_name_for(method_id, java_params, java_class.methods[java_method_id].length > 1, is_static == true)

                # Build the signature
                var nit_signature = new Array[String]
                nit_signature.add "fun {method_id}"
                if not java_params.is_empty then nit_signature.add "({nit_params.join(", ")})"

                # Return value
                var return_type = null
                if not java_return_type.is_void then
                        return_type = model.java_to_nit_type(java_return_type)

                        if not return_type.is_known and comment_unknown_types then c = "#"
                        if java_return_type.is_vararg then c = "#"

                        nit_signature.add ": " + return_type.to_s
                end

                # Build the call in Java
                var java_call
                if is_static == true then
                        java_call = java_class.class_type.package_name
                else java_call = "self"
                java_call += ".{java_method_id}({java_args.join(", ")})"

                if return_type != null then java_call = "return {java_return_type.return_cast}" + java_call

                # Tabulation
                var t = "\t"
                if is_static == true then t = ""
                var ct = c+t

                # Write
                file_out.write """
{{{t}}}# Java implementation: {{{java_return_type}}} {{{java_class}}}.{{{java_method_id}}}({{{java_params.join(", ")}}})
{{{ct}}}{{{nit_signature.join}}} in "Java" `{
{{{ct}}}        {{{java_call}}};
{{{ct}}}`}
"""
        end

        # Generate getter and setter to access an attribute, of field
        private fun generate_getter_setter(java_class: JavaClass, java_id: String,
                attribute: JavaAttribute)
        do
                var java_type = attribute.java_type
                var nit_type = model.java_to_nit_type(java_type)

                var nit_id = java_id
                if attribute.is_static then nit_id = java_class.class_type.extern_name.to_snake_case + "_" + nit_id
                nit_id = nit_id.to_nit_method_name
                nit_id = java_class.nit_name_for(nit_id, [java_type], false, attribute.is_static)

                var c = ""
                if not nit_type.is_known and comment_unknown_types then c = "#"
                if java_type.is_vararg then c = "#"

                var recv
                if attribute.is_static then
                        recv = java_class.class_type.package_name
                else recv = "self"

                # Tabulation
                var t = "\t"
                if attribute.is_static then t = ""
                var ct = c+t

                file_out.write """
{{{t}}}# Java getter: {{{java_class}}}.{{{java_id}}}
{{{ct}}}fun {{{nit_id}}}: {{{nit_type}}} in "Java" `{
{{{ct}}}        return {{{recv}}}.{{{java_id}}};
{{{ct}}}`}

{{{t}}}# Java setter: {{{java_class}}}.{{{java_id}}}
{{{ct}}}fun {{{nit_id}}}=(value: {{{nit_type}}}) in "Java" `{
{{{ct}}}        {{{recv}}}.{{{java_id}}} = value;
{{{ct}}}`}

"""
        end

        # Generate getter and setter to access an attribute, of field
        private fun generate_constructor(java_class: JavaClass, constructor: JavaConstructor, name: String)
        do
                var c = ""
                var nit_params_s = ""
                var java_params_s = ""

                if constructor.params.not_empty then
                        var nit_params = new Array[String]
                        var java_params = new Array[String]
                        var param_id = 'a'
                        for java_type in constructor.params do

                                java_params.add "{java_type.param_cast}{param_id}"

                                var nit_type = model.java_to_nit_type(java_type)
                                nit_params.add  "{param_id}: {nit_type}"
                                param_id = param_id.successor(1)

                                if not nit_type.is_known and comment_unknown_types then c = "#"
                                if java_type.is_vararg then c = "#"
                        end

                        nit_params_s = "(" + nit_params.join(", ") + ")"
                        java_params_s = java_params.join(", ")
                end

                file_out.write """
        # Java constructor: {{{java_class}}}
{{{c}}} new {{{name}}}{{{nit_params_s}}} in "Java" `{
{{{c}}}         return new {{{java_class.class_type.package_name}}}({{{java_params_s}}});
{{{c}}} `}

"""
        end

        private fun generate_primitive_array(java_class: JavaClass, dimensions: Int)
        do
                var base_java_type = java_class.class_type
                var java_type = base_java_type.clone
                java_type.array_dimension = dimensions

                var base_nit_type = model.java_to_nit_type(base_java_type)
                var nit_type = model.java_to_nit_type(java_type)

                file_out.write """
# Java primitive array: {{{java_type}}}
extern class {{{nit_type}}} in "Java" `{ {{{java_type.extern_equivalent}}} `}
        super AbstractJavaArray[{{{base_nit_type}}}]

        # Get a new array of the given `size`
        new(size: Int) in "Java" `{ return new {{{base_java_type}}}[(int)size]; `}

        redef fun [](i) in "Java" `{ return self[(int)i]; `}

        redef fun []=(i, e) in "Java" `{ self[(int)i] = e; `}

        redef fun length in "Java" `{ return self.length; `}

"""
                generate_jni_services(java_type)
                file_out.write """
end

"""
        end

        # Generate JNI related services
        #
        # For now, mostly avoid issue #845, but more services could be generated as needed.
        private fun generate_jni_services(java_type: JavaType)
        do
                var nit_type = model.java_to_nit_type(java_type)

                file_out.write """
        redef fun new_global_ref import sys, Sys.jni_env `{
                Sys sys = {{{nit_type}}}_sys(self);
                JNIEnv *env = Sys_jni_env(sys);
                return (*env)->NewGlobalRef(env, self);
        `}

        redef fun pop_from_local_frame_with_env(jni_env) `{
                return (*jni_env)->PopLocalFrame(jni_env, self);
        `}
"""
        end
end

redef class Sys
        # List of Nit keywords
        #
        # These may also be keywords in Java, but there they would be used capitalized.
        private var nit_keywords = new HashSet[String].from(["abort", "abstract", "and", "assert",
                "break", "class", "continue", "do", "else", "end", "enum", "extern", "false", "implies",
                "import", "init", "interface", "intrude", "if", "in", "is", "isa", "isset", "for", "label",
                "loop", "module", "new", "not", "null", "nullable", "or", "package", "private",
                "protected", "public", "return", "self", "super", "then", "true", "type", "var", "while",

        # Top-level methods
                "class_name", "get_time", "hash", "inspect", "inspect_head", "is_same_type",
                "is_same_instance", "object_id", "output", "output_class_name", "sys", "to_s",

        # Pointer or JavaObject methods
                "free"])

        # Name of methods used at the top-level
        #
        # Used by `JavaClass::nit_name_for` with static properties.
        private var top_level_used_names = new HashSet[String]
end

redef class String

        # Convert the Java method name `self` to the Nit style
        #
        # * Converts to snake case
        # * Strips `Get` and `Set`
        # * Add suffix `=` to setters
        fun to_nit_method_name: String
        do
                var name = self.to_snake_case

                # Strip the '_' prefix
                while name.has_prefix("_") do name = name.substring(1, name.length-1)

                # Escape Nit keywords
                if nit_keywords.has(name) then name += "_"

                # If the name starts by something other than a letter, prefix with `java_`
                if not name.chars.first.is_letter then name = "java_" + name

                name = name.replace("$", "_")

                return name
        end
end

redef class JavaClass
        # Property names used in this class
        private var used_names = new HashSet[String]

        # Get an available property name for the Java property with `name` and parameters
        #
        # If `use_parameters_name` then expect that there will be conflicts,
        # so use the types of `parameters` to build the name.
        private fun nit_name_for(name: String, parameters: Array[JavaType], use_parameters_name: Bool, is_static: Bool): String
        do
                # Append the name of each parameter
                if use_parameters_name then
                        for param in parameters do
                                name += "_" + param.id
                        end
                end

                # Set of property names, local or top-level
                var used_names
                if is_static then
                        used_names = sys.top_level_used_names
                else used_names = self.used_names

                # As a last resort, append numbers to the name
                var base_name = name
                var count = 1
                while used_names.has(name) do
                        name = base_name + count.to_s
                        count += 1
                end

                used_names.add name
                return name
        end
end