nitpretty: factorizes block visit on APropdefs

[nit.git] / src / pretty.nit

# 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.

# Library used to pretty print Nit code.
#
# Usage:
#
#     import parser_util
#     var tc = new ToolContext
#     var nmodule = tc.parse_something("class A\nfun   toto :  Int  do   return   5\nend")
#     var ppv = new PrettyPrinterVisitor
#     var pmodule = ppv.pretty(nmodule)
#     assert pmodule.write_to_string == """
#     class A
#     \tfun toto: Int do return 5
#     end"""
#
# See `nitpretty` tool for more documentation.
module pretty

import template
import toolcontext
import modelbuilder
import astutil

# The `PrettyPrinterVisitor` is used to visit a node and pretty print it.
#
# The main method here is `visit` that performs the pretty printing of a `ANode`.
#
# Because some tokens like `TComment` are not stored in the AST,
# we visit the AST like traditionnal visitor and also maintain a
# pointer to the `current_token` (actually the next one to be printed).
#
# Visited productions are in charges to move the token pointer using methods such as:
#
# * `consume`: print `current_token` and move to the next one
# * `skip`: move to the next token without printing the current one
# * `skip_to`: move to a specified token skipping all the tokens before
# * `catch_up`: consume all the tokens between `current_token` and a specified token
# * `finish_line`: consume all the tokens between `current_token` and the end of line
class PrettyPrinterVisitor
        # Pretty print `n`.
        fun pretty(n: ANode): Template do
                clear
                n.parentize_tokens

                if n isa Prod then
                        current_token = n.first_token
                        visit n
                else if n isa Token then
                        var p = n.parent

                        while p != null and not p isa Prod do
                                p = p.parent
                        end

                        current_token = p.first_token
                        visit p
                end

                return tpl.as(not null)
        end

        # Pretty print the whole `nmodule` with comments before and after.
        fun pretty_nmodule(nmodule: AModule): Template do
                clear
                nmodule.parentize_tokens
                current_token = nmodule.location.file.first_token
                visit nmodule
                catch_up nmodule.location.file.last_token
                tpl.add "\n"
                return tpl.as(not null)
        end

        # Prepare `self` for a new visit.
        private fun clear do
                tpl = new Template
                current_token = null
                indent = 0
                current_length = 0
                previous_length = 0
                wait_addn = 0
        end

        # Visit `n` if not null.
        fun visit(n: nullable ANode) do
                if n == null then return
                n.accept_pretty_printer self
        end

        # Visit a list of `Anode`.
        fun visit_list(n: nullable ANodes[ANode]) do
                if n == null then return
                n.accept_pretty_printer self
        end

        # Is the node inlinable and can fit on the line.
        fun can_inline(n: nullable ANode): Bool do
                if n == null then return true
                if n.must_be_inline then return true
                if n.must_be_block then return false
                # check length
                if n.collect_length + current_length > max_size then return false
                # check block is inlinable
                return n.is_inlinable
        end

        # Collect all `TComment` between `from` and `to`.
        fun collect_comments(from: nullable ANode, to: nullable ANode): Array[TComment] do
                var res = new Array[TComment]
                if from isa Prod then from = from.first_token
                if to isa Prod then to = to.first_token
                if from == null or to == null then return res

                while from != to do
                        if from isa TComment then res.add from
                        from = from.as(Token).next_token
                end

                return res
        end

        # Token under cursor.
        #
        # This is the next token to visit.
        var current_token: nullable Token = null

        # Skip the `current_token`.
        fun skip do current_token = current_token.next_token

        # Skip `current_token` until the end of line.
        fun skip_line do current_token = current_token.last_real_token_in_line

        # Skip `current_token` until `target` is reached.
        fun skip_to(target: nullable Token) do
                if target == null then return
                while current_token != target do skip
        end

        # Visit `current_token`.
        fun consume(token: String) do
                assert current_token.text == token
                visit current_token
        end

        # Is there token to visit between `current_token` and `target`?
        fun need_catch_up(target: nullable Token): Bool do
                if target == null then return false
                return current_token != target
        end

        # Visit all tokens between `current_token` and `target`.
        fun catch_up(target: nullable ANode) do
                if target == null then return
                if current_token == null then return
                var token: Token
                if target isa Token then
                        token = target
                else if target isa Prod then
                        token = target.first_token.as(not null)
                else
                        abort
                end
                assert current_token.location <= token.location
                while current_token != token do visit current_token
        end

        # Visit all tokens between `current_token` and the end of line.
        fun finish_line do
                if current_token isa TComment then
                        adds
                        visit current_token
                end

                while current_token isa TEol do skip
        end

        # The template under construction.
        private var tpl: nullable Template = null

        # Current indent level.
        var indent = 0

        # Size of a tabulation in spaces.
        var tab_size = 8

        # Max line size.
        var max_size = 80

        # Length of the current line.
        var current_length = 0

        # Length of the previous line.
        var previous_length = 0

        # Is the last line a blank line?
        fun last_line_is_blank: Bool do return previous_length == 0

        # Add `t` to current template.
        fun add(t: String) do
                if t.is_empty then return
                while wait_addn > 0 do
                        tpl.add "\n"
                        wait_addn -= 1
                end
                tpl.add t
                current_length += t.length
        end

        # Add a `'\n'`.
        fun addn do
                if current_length == 0 and last_line_is_blank then return
                previous_length = current_length
                current_length = 0
                wait_addn += 1
        end

        # End of line chars are stored until another char is added.
        # This avoid empty files with only a '`\n`'.
        private var wait_addn = 0

        # Add `'\t' * indent`.
        fun addt do add "\t" * indent

        # Add a space.
        fun adds do add " "

        # Visit explicit receiver, implicit self will be ignored.
        fun visit_recv(n_expr: AExpr) do
                if not n_expr isa AImplicitSelfExpr then
                        visit n_expr
                        consume "."
                end
        end
end

# Base framework redefs

redef class ANodes[E]
        private fun accept_pretty_printer(v: PrettyPrinterVisitor) do
                for e in self do
                        var e_can_inline = v.can_inline(e)

                        if e != first then
                                if not e_can_inline then
                                        v.add ","
                                        v.addn
                                        v.addt
                                        v.addt
                                else
                                        v.add ", "
                                end
                        end

                        v.visit e
                end
        end
end

redef class ANode
        # Start visit of `self` using a `PrettyPrinterVisitor`
        private fun accept_pretty_printer(v: PrettyPrinterVisitor) is abstract

        # Collect the length (in `Char`) of the node.
        private fun collect_length: Int is abstract

        # Is `self` printable in one line?
        private fun is_inlinable: Bool do return true

        # Force `self` to be rendered as a block.
        private var force_block = false

        # Does `self` have to be rendered as a block?
        private fun must_be_block: Bool do return force_block

        # Force `self` to be rendered as a line.
        private var force_inline = false

        # Does `self` have be rendered as a line?
        private fun must_be_inline: Bool do
                if parent != null and parent.must_be_inline then return true
                return force_inline
        end

        # Does `self` was written in one line before transformation?
        private fun was_inline: Bool is abstract
end

redef class Token
        redef fun accept_pretty_printer(v) do
                v.add text.trim
                v.current_token = next_token
        end

        redef fun collect_length do return text.length
        redef fun is_inlinable do return true
        redef fun was_inline do return true
end

redef class Prod
        redef fun accept_pretty_printer(v) do v.visit first_token

        # The token where the production really start (skipping ADoc).
        private fun start_token: nullable Token do return first_token

        # Collect all `TComment` contained in the production
        # (between `start_token` and `end_token`).
        private fun collect_comments: Array[TComment] do
                var res = new Array[TComment]
                if start_token == null or last_token == null then return res
                var token = start_token

                while token != last_token do
                        if token isa TComment then res.add token
                        token = token.next_token
                end

                return res
        end

        redef fun collect_length do
                var res = 0
                if start_token == null or last_token == null then return res
                var token = start_token

                while token != last_token do
                        res += token.text.length
                        token = token.next_token
                end

                res += token.text.length
                return res
        end

        redef fun was_inline do
                return first_token.location.line_start == last_token.location.line_end
        end
end

# Comments

redef class TComment
        redef fun accept_pretty_printer(v) do
                if is_adoc then
                        v.addt
                        super
                        v.addn
                        return
                end

                if is_licence then
                        super
                        v.addn
                        if is_last_in_group then v.addn
                        return
                end

                if is_orphan then
                        v.addn
                        v.addt
                        super
                        v.addn
                        v.addn
                        return
                end

                if is_inline then
                        if next_token isa TComment and is_first_in_group then v.addn
                        v.addt
                        super
                        v.addn
                        var prev_token = self.prev_token
                        if prev_token isa TComment and prev_token.is_inline and is_last_in_group then v.addn
                        return
                end

                super
        end

        # Is `self` part of an `ADoc`?
        private fun is_adoc: Bool do return parent isa ADoc and parent.parent != null

        # Is `self` part of a licence?
        private fun is_licence: Bool do
                var prev_token = self.prev_token

                if prev_token == null then
                        return true
                else if prev_token isa TComment then
                        return prev_token.is_licence
                else
                        return false
                end
        end

        # Is `self` starts and ends its line?
        private fun is_inline: Bool do
                return self == first_real_token_in_line and self == last_real_token_in_line
        end

        # Is `self` an orphan line (blank before and after)?
        private fun is_orphan: Bool do
                return prev_token isa TEol and
                   (prev_token.prev_token isa TEol or prev_token.prev_token isa TComment) and
                   next_token isa TEol
        end

        # Is `self` the first comment of a group of comment?
        private fun is_first_in_group: Bool do return not prev_token isa TComment

        # Is `self` the last comment of a group of comments?
        private fun is_last_in_group: Bool do return not next_token isa TComment
end

redef class ADoc
        redef fun accept_pretty_printer(v) do for comment in n_comment do v.visit comment
        redef fun is_inlinable do return n_comment.length <= 1
end

# Annotations

redef class AAnnotations
        redef fun accept_pretty_printer(v) do
                v.adds
                v.consume "is"

                if v.can_inline(self) then
                        v.adds
                        for n_item in n_items do
                                v.visit n_item
                                if n_item != n_items.last then
                                        v.add ", "
                                end
                        end
                        v.finish_line
                else if n_items.length > 1 then
                        v.addn
                        v.indent += 1

                        for n_item in n_items do
                                v.addt
                                v.visit n_item
                                v.finish_line
                                v.addn
                        end

                        v.indent -= 1
                end
                if not was_inline and v.current_token isa TKwend then v.skip
        end

        redef fun is_inlinable do
                if not super then return false
                for annot in n_items do if not annot.is_inlinable then return false
                return true
        end
end

redef class AAnnotation
        redef fun accept_pretty_printer(v) do
                v.visit n_atid
                if not n_args.is_empty then
                        if n_opar == null then
                                v.adds
                        else
                                v.visit n_opar
                        end
                        v.visit_list n_args
                        v.visit n_cpar
                end
        end
end

redef class ATypeExpr
        redef fun accept_pretty_printer(v) do v.visit n_type
end

# Modules

redef class AModule
        redef fun accept_pretty_printer(v) do
                v.catch_up start_token
                v.visit n_moduledecl

                if not n_imports.is_empty then
                        v.addn

                        for n_import in n_imports do
                                v.catch_up n_import
                                v.visit n_import
                        end
                end

                if not n_extern_code_blocks.is_empty then
                        v.addn

                        for n_extern_block in n_extern_code_blocks do
                                v.catch_up n_extern_block
                                v.visit n_extern_block
                                v.addn
                                if n_extern_block != n_extern_code_blocks.last then v.addn
                        end

                        if not n_classdefs.is_empty then v.addn
                end

                if not n_classdefs.is_empty then
                        v.addn

                        for n_classdef in n_classdefs do
                                v.catch_up n_classdef
                                v.visit n_classdef
                                if n_classdef != n_classdefs.last then v.addn
                        end
                end

                assert v.indent == 0
        end

        # Skip doc if any.
        redef fun start_token do
                if n_moduledecl != null then return n_moduledecl.first_token
                if not n_imports.is_empty then return n_imports.first.first_token
                if not n_classdefs.is_empty then return n_classdefs.first.first_token
                return first_token
        end

        redef fun is_inlinable do return false
end

redef class AModuledecl
        redef fun accept_pretty_printer(v) do
                v.visit n_doc
                v.visit n_kwmodule
                v.adds
                v.visit n_name

                if n_annotations != null then
                        var annot_inline = v.can_inline(n_annotations)
                        v.visit n_annotations

                        if not annot_inline then
                                if v.current_token isa TKwend then
                                        v.consume "end"
                                        v.finish_line
                                else
                                        v.add "end"
                                end
                        end
                end

                v.finish_line
                v.addn
        end
end

redef class AModuleName
        redef fun accept_pretty_printer(v) do
                for path in n_path do
                        v.visit path
                        v.add "::"
                end

                v.visit n_id
        end
end

redef class ANoImport
        redef fun accept_pretty_printer(v) do
                v.visit n_kwimport
                v.adds
                v.visit n_kwend
                v.finish_line
                v.addn
        end
end

redef class AStdImport
        redef fun accept_pretty_printer(v) do
                if not n_visibility isa APublicVisibility then
                        v.visit n_visibility
                        v.adds
                end

                v.visit n_kwimport
                v.adds
                v.visit n_name
                v.finish_line
                v.addn
        end
end

# Classes

redef class AClassdef
        redef fun accept_pretty_printer(v) do
                for n_propdef in n_propdefs do
                        v.catch_up n_propdef

                        if n_propdef.n_doc != null or not v.can_inline(n_propdef) then
                                if n_propdef != n_propdefs.first then v.addn
                                v.visit n_propdef
                                if n_propdef != n_propdefs.last then v.addn
                        else
                                v.visit n_propdef
                        end
                end
        end
end

redef class AStdClassdef
        redef fun accept_pretty_printer(v) do
                v.visit n_doc
                var can_inline = v.can_inline(self)

                if not n_visibility isa APublicVisibility then
                        v.visit n_visibility
                        v.adds
                end

                if n_kwredef != null then
                        v.visit n_kwredef
                        v.adds
                end

                v.visit n_classkind
                v.adds
                v.visit n_id

                if not n_formaldefs.is_empty then
                        v.consume "["
                        v.visit_list n_formaldefs
                        v.consume "]"
                end

                if n_extern_code_block != null then
                        v.adds
                        v.visit n_extern_code_block
                end

                if can_inline then
                        v.adds

                        if not n_superclasses.is_empty then
                                for n_superclass in n_superclasses do
                                        v.visit n_superclass
                                        v.adds
                                end
                        end
                else
                        v.finish_line
                        v.addn
                        v.indent += 1

                        for n_superclass in n_superclasses do
                                v.catch_up n_superclass
                                v.addt
                                v.visit n_superclass
                                v.finish_line
                                v.addn
                        end

                        if not n_superclasses.is_empty and not n_propdefs.is_empty then
                                v.addn
                        end

                        super
                        v.catch_up n_kwend
                        v.indent -= 1
                end

                v.visit n_kwend
                v.finish_line
                v.addn
                assert v.indent == 0
        end

        redef fun is_inlinable do
                if not super then return false
                if not n_propdefs.is_empty then return false
                if n_superclasses.length > 1 then return false
                if not collect_comments.is_empty then return false
                return true
        end

        redef fun start_token do
                if not n_visibility isa APublicVisibility then return n_visibility.first_token
                if n_kwredef != null then return n_kwredef
                return n_classkind.first_token
        end
end

redef class AAbstractClasskind
        redef fun accept_pretty_printer(v) do
                v.visit n_kwabstract
                v.adds
                v.visit n_kwclass
        end
end

redef class AExternClasskind
        redef fun accept_pretty_printer(v) do
                v.visit n_kwextern
                v.adds
                v.visit n_kwclass
        end
end

redef class AFormaldef
        redef fun accept_pretty_printer(v) do
                v.visit n_id

                if n_type != null then
                        v.consume ":"
                        v.adds
                        v.visit n_type
                end
        end
end

redef class AType
        redef fun accept_pretty_printer(v) do
                if n_kwnullable != null then
                        v.visit n_kwnullable
                        v.adds
                end

                v.visit n_id

                if not n_types.is_empty then
                        v.consume "["
                        v.visit_list n_types
                        v.consume "]"
                end
        end
end

redef class ASuperclass
        redef fun accept_pretty_printer(v) do
                v.visit n_kwsuper
                v.adds
                v.visit n_type
        end
end

# Properties

redef class APropdef
        redef fun accept_pretty_printer(v) do
                v.visit n_doc
                v.addt

                if not n_visibility isa APublicVisibility then
                        v.visit n_visibility
                        v.adds
                end

                if n_kwredef != null then
                        v.visit n_kwredef
                        v.adds
                end
        end

        # Factorize annotations visit for all APropdef.
        #
        # Return true if annotations were inlined.
        fun visit_annotations(v: PrettyPrinterVisitor, n_annotations: nullable AAnnotations): Bool do
                var res = v.can_inline(n_annotations)
                if n_annotations != null then v.visit n_annotations
                return res
        end

        # Factorize block visit for APropdefs.
        #
        # Were annotations printed inline? If so, we need to print the block differently.
        fun visit_block(v: PrettyPrinterVisitor, n_block: nullable AExpr, annot_inline: Bool) do
                if n_block == null then return
                while not v.current_token isa TKwdo do v.skip
                if n_annotations != null and not annot_inline then
                        v.addt
                else
                        v.adds
                end
                v.consume "do"

                if v.can_inline(n_block) then
                        v.adds

                        if n_block isa ABlockExpr then
                                if n_block.n_expr.is_empty then
                                        v.visit n_block.n_kwend
                                else
                                        v.visit n_block.n_expr.first
                                        v.current_token = n_block.n_kwend
                                        v.skip
                                end
                        else
                                v.visit n_block
                                if v.current_token isa TKwend then v.skip
                        end
                else
                        v.finish_line
                        v.addn
                        v.indent += 1

                        if n_block isa ABlockExpr then
                                n_block.force_block = true
                                v.visit n_block
                                v.catch_up n_block.n_kwend
                        else
                                v.addt
                                v.visit n_block
                                v.addn
                        end

                        v.indent -= 1
                        v.addt
                        if n_block isa ABlockExpr then
                                v.visit n_block.n_kwend
                        else
                                v.add "end"
                        end
                end
                v.finish_line
        end

        redef fun start_token do
                if n_doc == null then return super
                return n_doc.last_token.next_token
        end
end

redef class AAttrPropdef
        redef fun accept_pretty_printer(v) do
                super
                v.visit n_kwvar
                v.adds
                v.visit n_id2

                if n_type != null then
                        v.consume ":"
                        v.adds
                        v.visit n_type
                end

                if n_expr != null then
                        v.adds
                        v.consume "="
                        v.adds
                        v.visit n_expr
                end

                var annot_inline = visit_annotations(v, n_annotations)
                visit_block(v, n_block, annot_inline)
                v.finish_line
                v.addn
        end

        redef fun first_token do
                if n_doc != null then return n_doc.first_token
                if not n_visibility isa APublicVisibility then return n_visibility.first_token
                if n_kwredef != null then return n_kwredef
                return n_kwvar
        end

        redef fun is_inlinable do return true
end

redef class ATypePropdef
        redef fun accept_pretty_printer(v) do
                super
                v.visit n_kwtype
                v.adds
                v.visit n_id
                v.consume ":"
                v.adds
                v.visit n_type
                visit_annotations(v, n_annotations)
                v.finish_line
                v.addn
        end

        redef fun is_inlinable do return true
end

redef class AMethPropdef
        redef fun accept_pretty_printer(v) do
                #  TODO: Handle extern annotations

                var before = v.indent
                super
                if n_kwinit != null then v.visit n_kwinit
                if n_kwmeth != null then v.visit n_kwmeth
                if n_kwnew != null then v.visit n_kwnew

                if not n_methid == null then
                        v.adds
                        v.visit n_methid
                end

                v.visit n_signature

                var annot_inline = visit_annotations(v, n_annotations)

                if n_extern_calls != null or n_extern_code_block != null then
                        v.adds
                        if n_extern_calls != null then v.visit n_extern_calls
                        if n_extern_code_block != null then v.visit n_extern_code_block
                end

                visit_block(v, n_block, annot_inline)
                v.addn
                assert v.indent == before
        end

        # Can be inlined if:
        # * block is empty or can be inlined
        # * contains no comments
        redef fun is_inlinable do
                if not super then return false
                if n_annotations != null and not n_annotations.is_inlinable then return false
                if n_block != null and not n_block.is_inlinable then return false
                if n_extern_calls != null and not n_extern_calls.is_inlinable then return false
                if n_extern_code_block != null and not n_extern_code_block.is_inlinable then return false
                if not collect_comments.is_empty then return false
                return true
        end
end

redef class AMainMethPropdef
        redef fun accept_pretty_printer(v) do
                v.visit n_block
                v.addn
        end
end

redef class ASignature
        redef fun accept_pretty_printer(v) do
                if not n_params.is_empty then
                        v.consume "("
                        v.visit_list n_params
                        v.consume ")"
                end

                if n_type != null then
                        v.consume ":"
                        v.adds
                        v.visit n_type
                end
        end
end

redef class AParam
        redef fun accept_pretty_printer(v) do
                v.visit n_id

                if n_type != null then
                        v.consume ":"
                        v.adds
                        v.visit n_type
                end

                if n_dotdotdot != null then v.visit n_dotdotdot
        end
end

# Extern

redef class AExternCalls
        redef fun accept_pretty_printer(v) do
                var can_inline = v.can_inline(self)
                v.visit n_kwimport

                if can_inline then
                        v.adds
                        v.visit_list n_extern_calls
                else
                        v.addn
                        v.addt
                        v.addt
                        v.visit_list n_extern_calls
                end

                v.adds
        end
end

redef class AFullPropExternCall
        redef fun accept_pretty_printer(v) do
                v.visit n_type
                v.visit n_dot
                v.visit n_methid
        end
end

redef class ALocalPropExternCall
        redef fun accept_pretty_printer(v) do v.visit n_methid
end

redef class AInitPropExternCall
        redef fun accept_pretty_printer(v) do v.visit n_type
end

redef class ACastAsExternCall
        redef fun accept_pretty_printer(v) do
                v.visit n_from_type
                v.visit n_dot
                v.visit n_kwas
                v.consume "("
                v.visit n_to_type
                v.consume ")"
        end
end

redef class AAsNullableExternCall
        redef fun accept_pretty_printer(v) do
                v.visit n_type
                v.consume "."
                v.visit n_kwas
                v.adds
                v.visit n_kwnullable
        end
end

redef class AAsNotNullableExternCall
        redef fun accept_pretty_printer(v) do
                v.visit n_type
                v.consume "."
                v.visit n_kwas
                v.adds
                v.visit n_kwnot
                v.adds
                v.visit n_kwnullable
        end
end

redef class AExternCodeBlock
        redef fun accept_pretty_printer(v) do
                if n_in_language != null then
                        v.visit n_in_language
                        v.adds
                end

                v.visit n_extern_code_segment
        end

        redef fun is_inlinable do
                if not super then return false
                return n_extern_code_segment.is_inlinable
        end
end

redef class AInLanguage
        redef fun accept_pretty_printer(v) do
                v.visit n_kwin
                v.adds
                v.visit n_string
        end
end

redef class TExternCodeSegment
        redef fun accept_pretty_printer(v) do
                var can_inline = v.can_inline(self)

                if can_inline then
                        super
                else
                        var text = text.substring(2, text.length - 4)
                        var lines = text.r_trim.split("\n")

                        if text.is_empty then
                                v.add "`\{`\}"
                        else
                                v.add "`\{"

                                if not lines.first.trim.is_empty then
                                        v.addn
                                        lines.first.l_trim
                                        v.indent += 1
                                        v.addt
                                        v.indent -= 1
                                end

                                for line in lines do
                                        v.add line.r_trim
                                        v.addn
                                end

                                v.addt
                                v.add "`\}"
                        end

                        v.current_token = next_token
                end
        end

        redef fun is_inlinable do
                if not super then return false
                return location.line_start == location.line_end
        end
end

# Blocks

redef class ABlockExpr
        redef fun accept_pretty_printer(v) do
                var before = v.indent
                var can_inline = v.can_inline(self)

                if can_inline and not n_expr.is_empty then
                        v.visit n_expr.first
                        v.finish_line
                else
                        for nexpr in n_expr do
                                var expr_inline = v.can_inline(nexpr)
                                if not expr_inline and nexpr != n_expr.first then v.addn
                                v.catch_up nexpr
                                v.addt
                                v.visit nexpr
                                v.finish_line
                                v.addn
                                if not expr_inline and nexpr != n_expr.last then v.addn
                        end
                end

                assert v.indent == before
        end

        redef fun is_inlinable do
                if not super then return false
                if not collect_comments.is_empty then return false

                if not n_expr.is_empty then
                        if n_expr.length > 1 then return false
                        if not n_expr.first.is_inlinable then return false
                end

                return true
        end
end

redef class AIfExpr
        redef fun accept_pretty_printer(v) do
                var before = v.indent
                var can_inline = v.can_inline(self)
                v.visit n_kwif
                v.adds

                if v.can_inline(n_expr) then
                        v.visit n_expr
                        v.adds
                else
                        v.visit n_expr
                        v.addn
                        v.addt
                end

                # skip comments before `then` token
                while not v.current_token isa TKwthen do v.skip
                v.consume "then"
                var n_else = self.n_else

                if can_inline then
                        v.adds
                        if n_then != null then v.visit n_then

                        if has_else(v) then
                                n_else.force_inline = true
                                v.adds
                                v.consume "else"
                                v.adds
                                v.visit n_else
                        else if n_then == null then
                                v.add "end"
                        end

                        v.skip_to last_token.last_real_token_in_line
                else
                        v.finish_line
                        v.addn
                        v.indent += 1

                        if n_then != null then
                                if n_then isa ABlockExpr then
                                        n_then.force_block = true
                                        v.visit n_then
                                else
                                        v.addt
                                        v.visit n_then
                                        v.addn
                                end
                        end

                        if has_else(v) then
                                while not v.current_token isa TKwelse do
                                        v.consume v.current_token.text
                                end

                                v.indent -= 1
                                v.addt
                                v.consume "else"

                                if n_else isa AIfExpr then
                                        n_else.force_block = true
                                        v.adds
                                        v.visit n_else
                                else
                                        v.finish_line
                                        v.addn
                                        v.indent += 1

                                        if n_else isa ABlockExpr then
                                                n_else.force_block = true
                                                v.visit n_else
                                        else
                                                v.addt
                                                v.visit n_else
                                                v.addn
                                        end

                                        if last_token isa TKwend then
                                                v.catch_up last_token
                                                v.indent -= 1
                                                v.addt
                                                v.consume "end"
                                        else
                                                v.indent -= 1
                                                v.addt
                                                v.add "end"
                                        end
                                end
                        else
                                if last_token.location >= v.current_token.location then v.catch_up last_token
                                v.indent -= 1
                                v.addt
                                v.add "end"
                                if v.current_token isa TKwend then v.skip
                        end
                end

                assert v.indent == before
        end

        redef fun is_inlinable do
                if not super then return false
                if n_then != null and not n_then.is_inlinable then return false
                var n_else = self.n_else
                if (n_else isa ABlockExpr and not n_else.n_expr.is_empty) or
                   (not n_else isa ABlockExpr and n_else != null) then
                        return false
                end
                if not collect_comments.is_empty then return false
                return true
        end

        # Does this `if` statement contains a `else` part?
        private fun has_else(v: PrettyPrinterVisitor): Bool do
                var n_else = n_else
                if n_else == null then return false
                var n_kwelse = collect_kwelse
                if n_kwelse == null then return false

                if n_else isa ABlockExpr then
                        var comments: Array[TComment]

                        if n_then == null then
                                comments = v.collect_comments(n_expr.last_token, n_else.last_token)
                        else
                                comments = v.collect_comments(n_then.last_token, n_else.last_token)
                        end

                        if not comments.is_empty then return true
                        return not n_else.n_expr.is_empty
                end

                return true
        end

        # Lookup for `else` token in `self`.
        private fun collect_kwelse: nullable TKwelse do
                var token = first_token

                while token != last_token do
                        if token isa TKwelse then return token
                        token = token.next_token
                end

                return null
        end
end

# Used to factorize work on loops.
private class ALoopHelper
        super AExpr

        fun loop_block: nullable ANode is abstract
        fun loop_label: nullable ANode is abstract

        fun visit_loop_block(v: PrettyPrinterVisitor) do
                var n_block = loop_block
                v.finish_line
                v.addn
                v.indent += 1

                if n_block isa ABlockExpr then
                        n_block.force_block = true
                        v.visit n_block
                        v.catch_up n_block.n_kwend
                        v.indent -= 1
                        v.addt
                        v.visit n_block.n_kwend
                else
                        v.addt
                        v.visit n_block
                        v.addn
                        v.indent -= 1
                        v.addt
                        v.add "end"
                end

                if loop_label != null then
                        v.adds
                        v.visit loop_label
                end
        end

        fun visit_loop_inline(v: PrettyPrinterVisitor) do
                var n_block = loop_block
                v.adds

                if n_block isa ABlockExpr then
                        if n_block.n_expr.is_empty then
                                v.visit n_block.n_kwend
                        else
                                v.visit n_block.n_expr.first
                                v.current_token = n_block.n_kwend
                                v.skip
                        end
                else
                        v.visit n_block
                        if v.current_token isa TKwend then v.skip
                end

                if loop_label != null then
                        v.adds
                        v.visit loop_label
                end
        end

        redef fun is_inlinable do
                var n_block = loop_block
                if not super then return false
                if n_block isa ABlockExpr and not n_block.is_inlinable then return false
                if not collect_comments.is_empty then return false
                return true
        end
end

redef class ALoopExpr
        super ALoopHelper

        redef fun loop_block do return n_block
        redef fun loop_label do return n_label

        redef fun accept_pretty_printer(v) do
                var can_inline = v.can_inline(self)
                v.visit n_kwloop
                if can_inline then visit_loop_inline v else visit_loop_block v
        end
end

redef class AWhileExpr
        super ALoopHelper

        redef fun loop_block do return n_block
        redef fun loop_label do return n_label

        redef fun accept_pretty_printer(v) do
                var can_inline = v.can_inline(self)
                v.visit n_kwwhile
                v.adds
                v.visit n_expr
                v.adds
                v.visit n_kwdo
                if can_inline then visit_loop_inline v else visit_loop_block v
        end
end

redef class ADoExpr
        super ALoopHelper

        redef fun loop_block do return n_block
        redef fun loop_label do return n_label

        redef fun accept_pretty_printer(v) do
                var can_inline = v.can_inline(self)
                v.visit n_kwdo
                if can_inline then visit_loop_inline v else visit_loop_block v
        end
end

redef class AForExpr
        super ALoopHelper

        redef fun loop_block do return n_block
        redef fun loop_label do return n_label

        redef fun accept_pretty_printer(v) do
                var can_inline = v.can_inline(self)
                v.visit n_kwfor
                v.adds

                for n_id in n_ids do
                        v.visit n_id
                        if n_id != n_ids.last then v.add ", "
                end

                v.adds
                v.consume "in"
                v.adds
                v.visit n_expr
                v.adds
                v.visit n_kwdo
                if can_inline then visit_loop_inline v else visit_loop_block v
        end
end

redef class ABreakExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_kwbreak

                if n_expr != null then
                        v.adds
                        v.visit n_expr
                end

                if n_label != null then
                        v.adds
                        v.visit n_label
                end
        end

        redef fun is_inlinable do return true
end

redef class AContinueExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_kwcontinue

                if n_expr != null then
                        v.adds
                        v.visit n_expr
                end

                if n_label != null then
                        v.adds
                        v.visit n_label
                end
        end

        redef fun is_inlinable do return true
end

# Calls

redef class ASendExpr
        redef fun is_inlinable do return true
end

redef class ACallExpr
        redef fun accept_pretty_printer(v) do
                var can_inline = v.can_inline(self)
                v.visit_recv n_expr

                if not n_expr isa AImplicitSelfExpr and not can_inline then
                        v.addn
                        v.addt
                        v.addt
                end

                v.visit n_id

                if not n_args.n_exprs.is_empty then
                        if is_stmt and n_args.n_exprs.length == 1 then
                                v.adds
                                if v.current_token isa TOpar then v.skip
                                v.visit n_args.n_exprs.first
                                if v.current_token isa TCpar then v.skip
                        else
                                if v.current_token isa TOpar then
                                        v.consume "("
                                else
                                        v.adds
                                end

                                v.visit_list n_args.n_exprs
                                if v.current_token isa TCpar then v.consume ")"
                        end
                end
        end

        # Is the call alone on its line?
        fun is_stmt: Bool do return parent isa ABlockExpr
end

redef class ACallAssignExpr
        redef fun accept_pretty_printer(v) do
                v.visit_recv n_expr
                v.visit n_id

                if not n_args.n_exprs.is_empty then
                        v.consume "("
                        v.visit_list n_args.n_exprs
                        v.consume ")"
                end

                v.adds
                v.consume "="
                v.adds
                v.visit n_value
        end
end

redef class ACallReassignExpr
        redef fun accept_pretty_printer(v) do
                v.visit_recv n_expr
                v.visit n_id

                if not n_args.n_exprs.is_empty then
                        v.consume "("
                        v.visit_list n_args.n_exprs
                        v.consume ")"
                end

                v.adds
                v.visit n_assign_op
                v.adds
                v.visit n_value
        end
end

redef class ABraExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_expr

                if not n_args.n_exprs.is_empty then
                        v.consume "["
                        v.visit_list n_args.n_exprs
                        v.consume "]"
                end
        end
end

redef class ABraAssignExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_expr

                if not n_args.n_exprs.is_empty then
                        v.consume "["
                        v.visit_list n_args.n_exprs
                        v.consume "]"
                end

                v.adds
                v.visit n_assign
                v.adds
                v.visit n_value
        end
end

redef class ABraReassignExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_expr

                if not n_args.n_exprs.is_empty then
                        v.consume "["
                        v.visit_list n_args.n_exprs
                        v.consume "]"
                end

                v.adds
                v.visit n_assign_op
                v.adds
                v.visit n_value
        end
end

redef class AAssignMethid
        redef fun accept_pretty_printer(v) do
                v.visit n_id
                v.visit n_assign
        end
end

redef class ABraMethid
        redef fun accept_pretty_printer(v) do
                v.visit n_obra
                v.visit n_cbra
        end
end

redef class ABraassignMethid
        redef fun accept_pretty_printer(v) do
                v.visit n_obra
                v.visit n_cbra
                v.visit n_assign
        end
end

redef class AInitExpr
        redef fun accept_pretty_printer(v) do
                if not n_expr isa AImplicitSelfExpr then
                        v.visit n_expr
                        v.consume "."
                end

                v.visit n_kwinit

                if not n_args.n_exprs.is_empty then
                        v.consume "("
                        v.visit_list n_args.n_exprs
                        v.consume ")"
                end
        end
end

redef class ANewExpr
        redef fun accept_pretty_printer(v) do
                var can_inline = v.can_inline(self)
                v.visit n_kwnew
                v.adds
                v.visit n_type

                if n_id != null then
                        v.consume "."

                        if not can_inline then
                                v.addn
                                v.addt
                                v.addt
                        end

                        v.visit n_id
                end

                if not n_args.n_exprs.is_empty then
                        v.consume "("
                        v.visit_list n_args.n_exprs
                        v.consume ")"
                end
        end

        redef fun is_inlinable do return true
end

# Attributes

redef class AAttrExpr
        redef fun accept_pretty_printer(v) do
                v.visit_recv n_expr
                v.visit n_id
        end

        redef fun is_inlinable do return true
end

redef class AAttrAssignExpr
        redef fun accept_pretty_printer(v) do
                v.visit_recv n_expr
                v.visit n_id
                v.adds
                v.visit n_assign
                v.adds
                v.visit n_value
        end
end

redef class AAttrReassignExpr
        redef fun accept_pretty_printer(v) do
                v.visit_recv n_expr
                v.visit n_id
                v.adds
                v.visit n_assign_op
                v.adds
                v.visit n_value
        end
end

# Exprs

redef class AVardeclExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_kwvar
                v.adds
                v.visit n_id

                if n_type != null then
                        v.consume ":"
                        v.adds
                        v.visit n_type
                end

                if n_expr != null then
                        v.adds
                        v.consume "="
                        v.adds
                        v.visit n_expr
                end
        end

        redef fun is_inlinable do return true
end

redef class AVarAssignExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_id
                v.adds
                v.visit n_assign
                v.adds
                v.visit n_value
        end
end

redef class AAssertExpr
        redef fun accept_pretty_printer(v) do
                var can_inline = v.can_inline(self)
                v.visit n_kwassert

                if n_id != null then
                        v.adds
                        v.visit n_id
                        v.consume ":"
                end

                v.adds
                v.visit n_expr
                var n_else = self.n_else

                if n_else != null then
                        v.adds
                        v.consume "else"

                        if can_inline then
                                v.adds
                                v.visit n_else
                        else
                                v.addn

                                if n_else isa ABlockExpr then
                                        v.indent += 1
                                        n_else.force_block = true
                                        v.visit n_else
                                        v.indent -= 1
                                        v.addt
                                        v.visit n_else.n_kwend
                                else
                                        v.indent += 1
                                        v.addt
                                        v.visit n_else
                                        v.addn
                                        v.indent -= 1
                                        v.addt
                                        v.add "end"
                                end
                        end
                end
        end

        redef fun is_inlinable do
                if not super then return false
                if n_else != null and not n_else.is_inlinable then return false
                return true
        end
end

redef class AReturnExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_kwreturn

                if n_expr != null then
                        v.adds
                        v.visit n_expr
                end
        end
end

redef class ASuperExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_kwsuper

                if not n_args.n_exprs.is_empty then
                        if is_stmt and n_args.n_exprs.length == 1 then
                                v.adds
                                if v.current_token isa TOpar then v.skip
                                v.visit n_args.n_exprs.first
                                if v.current_token isa TCpar then v.skip
                        else
                                if v.current_token isa TOpar then
                                        v.consume "("
                                else
                                        v.adds
                                end

                                v.visit_list n_args.n_exprs
                                if v.current_token isa TCpar then v.consume ")"
                        end
                end
        end

        # Is the call alone on its line?
        fun is_stmt: Bool do return self.first_token.is_starting_line

        redef fun is_inlinable do return true
end

redef class AOnceExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_kwonce
                v.adds
                v.visit n_expr
        end

        redef fun is_inlinable do return true
end

redef class AAbortExpr
        redef fun accept_pretty_printer(v) do v.visit n_kwabort
        redef fun is_inlinable do return true
end

redef class ANotExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_kwnot
                v.adds
                v.visit n_expr
        end
end

redef class AAsCastExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_expr
                v.consume "."
                v.visit n_kwas
                v.visit n_opar
                v.visit n_type
                v.visit n_cpar
        end
end

redef class AAsNotnullExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_expr
                v.consume "."
                v.visit n_kwas
                v.visit n_opar
                v.visit n_kwnot
                v.adds
                v.visit n_kwnull
                v.visit n_cpar
        end
end

# Binops

# Used to factorize work on Or, And, Implies and Binop expressions.
private class ABinOpHelper
        super AExpr

        fun bin_expr1: AExpr is abstract
        fun bin_expr2: AExpr is abstract

        # Operator string
        fun bin_op: String is abstract

        redef fun accept_pretty_printer(v) do
                var can_inline = v.can_inline(self)

                if not can_inline then
                        if (self isa ABinopExpr and bin_expr1 isa ABinopExpr) or
                           (self isa AAndExpr and (bin_expr1 isa AAndExpr or bin_expr1 isa AOrExpr)) or
                           (self isa AOrExpr and (bin_expr1 isa AAndExpr or bin_expr1 isa AOrExpr))
                        then
                                bin_expr1.force_block = true
                        end
                end

                v.visit bin_expr1
                v.adds
                v.consume bin_op

                if can_inline then
                        v.adds
                        v.visit bin_expr2
                else
                        v.addn
                        v.addt
                        v.addt
                        v.visit bin_expr2
                end
        end
end

redef class AAndExpr
        super ABinOpHelper

        redef fun bin_expr1 do return n_expr
        redef fun bin_expr2 do return n_expr2
        redef fun bin_op do return "and"
end

redef class AOrExpr
        super ABinOpHelper

        redef fun bin_expr1 do return n_expr
        redef fun bin_expr2 do return n_expr2
        redef fun bin_op do return "or"
end

redef class AImpliesExpr
        super ABinOpHelper

        redef fun bin_expr1 do return n_expr
        redef fun bin_expr2 do return n_expr2
        redef fun bin_op do return "implies"
end

redef class ABinopExpr
        super ABinOpHelper

        redef fun bin_expr1 do return n_expr
        redef fun bin_expr2 do return n_expr2
end

redef class AEqExpr
        redef fun bin_op do return "=="
end

redef class AGeExpr
        redef fun bin_op do return ">="
end

redef class AGgExpr
        redef fun bin_op do return ">>"
end

redef class AGtExpr
        redef fun bin_op do return ">"
end

redef class ALeExpr
        redef fun bin_op do return "<="
end

redef class ALlExpr
        redef fun bin_op do return "<<"
end

redef class ALtExpr
        redef fun bin_op do return "<"
end

redef class AMinusExpr
        redef fun bin_op do return "-"
end

redef class ANeExpr
        redef fun bin_op do return "!="
end

redef class APercentExpr
        redef fun bin_op do return "%"
end

redef class APlusExpr
        redef fun bin_op do return "+"
end

redef class ASlashExpr
        redef fun bin_op do return "/"
end

redef class AStarExpr
        redef fun bin_op do return "*"
end

redef class AStarstarExpr
        redef fun bin_op do return "**"
end

redef class AStarshipExpr
        redef fun bin_op do return "<=>"
end

redef class AIsaExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_expr
                v.adds
                v.consume "isa"
                v.adds
                v.visit n_type
        end
end

redef class AOrElseExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_expr
                v.adds
                v.consume "or"
                v.adds
                v.consume "else"
                v.adds
                v.visit n_expr2
        end

        redef fun is_inlinable do return true
end

# Syntax

redef class AUminusExpr
        redef fun accept_pretty_printer(v) do
                v.consume "-"
                v.visit n_expr
        end
end

redef class ANullExpr
        redef fun accept_pretty_printer(v) do v.visit n_kwnull
        redef fun is_inlinable do return true
end

redef class AParExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_opar
                v.visit n_expr
                v.visit n_cpar
        end
end

redef class AArrayExpr
        redef fun accept_pretty_printer(v) do
                v.consume "["
                v.visit_list n_exprs
                v.consume "]"
        end
end

redef class ACrangeExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_obra
                v.visit n_expr
                v.consume ".."
                v.visit n_expr2
                v.visit n_cbra
        end
end

redef class AOrangeExpr
        redef fun accept_pretty_printer(v) do
                v.visit n_obra
                v.visit n_expr
                v.consume ".."
                v.visit n_expr2
                v.visit n_cbra
        end
end

# Strings

redef class AStringFormExpr
        redef fun accept_pretty_printer(v) do
                var can_inline = v.can_inline(self)

                if can_inline then
                        v.visit n_string
                else
                        var text = n_string.text
                        var i = 0

                        while i < text.length do
                                v.add text[i].to_s

                                if v.current_length >= v.max_size and i <= text.length - 3 then
                                        v.add "\" +"
                                        v.addn
                                        v.indent += 1
                                        v.addt
                                        v.indent -= 1
                                        v.add "\""
                                end

                                i += 1
                        end

                        v.current_token = n_string.next_token
                end
        end
end

redef class ASuperstringExpr
        redef fun accept_pretty_printer(v) do
                for n_expr in n_exprs do v.visit n_expr
        end

        redef fun must_be_inline do
                if super then return true

                if not n_exprs.is_empty then
                        var first = n_exprs.first
                        return first isa AStringFormExpr and first.n_string.text.has_prefix("\"\"\"")
                end

                return false
        end
end