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[ruby/prism] Change inspect from recursive to a queue
We would previously cause a stack overflow if we parsed a file that was too deeply nested when we were calling inspect. Instead, we now use a queue of commands to do it linearly so we don't. ruby/prism@0f21f5bfe1
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,137 @@ | ||
| module Prism | ||
| # This visitor is responsible for composing the strings that get returned by | ||
| # the various #inspect methods defined on each of the nodes. | ||
| class InspectVisitor < Visitor | ||
| # Most of the time, we can simply pass down the indent to the next node. | ||
| # However, when we are inside a list we want some extra special formatting | ||
| # when we hit an element in that list. In this case, we have a special | ||
| # command that replaces the subsequent indent with the given value. | ||
| class Replace # :nodoc: | ||
| attr_reader :value | ||
|
|
||
| def initialize(value) | ||
| @value = value | ||
| end | ||
| end | ||
|
|
||
| private_constant :Replace | ||
|
|
||
| # The current prefix string. | ||
| attr_reader :indent | ||
|
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||
| # The list of commands that we need to execute in order to compose the | ||
| # final string. | ||
| attr_reader :commands | ||
|
|
||
| # Initializes a new instance of the InspectVisitor. | ||
| def initialize(indent = +"") | ||
| @indent = indent | ||
| @commands = [] | ||
| end | ||
|
|
||
| # Compose an inspect string for the given node. | ||
| def self.compose(node) | ||
| visitor = new | ||
| node.accept(visitor) | ||
| visitor.compose | ||
| end | ||
|
|
||
| # Compose the final string. | ||
| def compose | ||
| buffer = +"" | ||
| replace = nil | ||
|
|
||
| until commands.empty? | ||
| # @type var command: String | node | Replace | ||
| # @type var indent: String | ||
| command, indent = *commands.shift | ||
|
|
||
| case command | ||
| when String | ||
| buffer << (replace || indent) | ||
| buffer << command | ||
| replace = nil | ||
| when Node | ||
| visitor = InspectVisitor.new(indent) | ||
| command.accept(visitor) | ||
| @commands = [*visitor.commands, *@commands] | ||
| when Replace | ||
| replace = command.value | ||
| else | ||
| raise "Unknown command: #{command.inspect}" | ||
| end | ||
| end | ||
|
|
||
| buffer | ||
| end | ||
| <%- nodes.each do |node| -%> | ||
|
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| # Inspect a <%= node.name %> node. | ||
| def visit_<%= node.human %>(node) | ||
| commands << [inspect_node(<%= node.name.inspect %>, node), indent] | ||
| <%- node.fields.each_with_index do |field, index| -%> | ||
| <%- pointer = index == node.fields.length - 1 ? "└── " : "├── " -%> | ||
| <%- preadd = index == node.fields.length - 1 ? " " : "│ " -%> | ||
| <%- case field -%> | ||
| <%- when Prism::Template::NodeListField -%> | ||
| commands << ["<%= pointer %><%= field.name %>: (length: #{(<%= field.name %> = node.<%= field.name %>).length})\n", indent] | ||
| if <%= field.name %>.any? | ||
| <%= field.name %>[0...-1].each do |child| | ||
| commands << [Replace.new("#{indent}<%= preadd %>├── "), indent] | ||
| commands << [child, "#{indent}<%= preadd %>│ "] | ||
| end | ||
| commands << [Replace.new("#{indent}<%= preadd %>└── "), indent] | ||
| commands << [<%= field.name %>[-1], "#{indent}<%= preadd %> "] | ||
| end | ||
| <%- when Prism::Template::NodeField -%> | ||
| commands << ["<%= pointer %><%= field.name %>:\n", indent] | ||
| commands << [node.<%= field.name %>, "#{indent}<%= preadd %>"] | ||
| <%- when Prism::Template::OptionalNodeField -%> | ||
| if (<%= field.name %> = node.<%= field.name %>).nil? | ||
| commands << ["<%= pointer %><%= field.name %>: ∅\n", indent] | ||
| else | ||
| commands << ["<%= pointer %><%= field.name %>:\n", indent] | ||
| commands << [<%= field.name %>, "#{indent}<%= preadd %>"] | ||
| end | ||
| <%- when Prism::Template::ConstantField, Prism::Template::ConstantListField, Prism::Template::StringField, Prism::Template::UInt8Field, Prism::Template::UInt32Field, Prism::Template::IntegerField, Prism::Template::DoubleField -%> | ||
| commands << ["<%= pointer %><%= field.name %>: #{node.<%= field.name %>.inspect}\n", indent] | ||
| <%- when Prism::Template::OptionalConstantField -%> | ||
| if (<%= field.name %> = node.<%= field.name %>).nil? | ||
| commands << ["<%= pointer %><%= field.name %>: ∅\n", indent] | ||
| else | ||
| commands << ["<%= pointer %><%= field.name %>: #{<%= field.name %>.inspect}\n", indent] | ||
| end | ||
| <%- when Prism::Template::FlagsField -%> | ||
| <%- flag = flags.find { |flag| flag.name == field.kind }.tap { |flag| raise unless flag } -%> | ||
| flags = [<%= flag.values.map { |value| "(\"#{value.name.downcase}\" if node.#{value.name.downcase}?)" }.join(", ") %>].compact | ||
| commands << ["<%= pointer %><%= field.name %>: #{flags.empty? ? "∅" : flags.join(", ")}\n", indent] | ||
| <%- when Prism::Template::LocationField, Prism::Template::OptionalLocationField -%> | ||
| commands << ["<%= pointer %><%= field.name %>: #{inspect_location(node.<%= field.name %>)}\n", indent] | ||
| <%- end -%> | ||
| <%- end -%> | ||
| end | ||
| <%- end -%> | ||
|
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| private | ||
|
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||
| # Compose a header for the given node. | ||
| def inspect_node(name, node) | ||
| result = +"@ #{name} (" | ||
|
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| location = node.location | ||
| result << "location: (#{location.start_line},#{location.start_column})-(#{location.end_line},#{location.end_column})" | ||
| result << ", newline: true" if node.newline? | ||
|
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| result << ")\n" | ||
| end | ||
|
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||
| # Compose a string representing the given inner location field. | ||
| def inspect_location(location) | ||
| if location | ||
| "(#{location.start_line},#{location.start_column})-(#{location.end_line},#{location.end_column}) = #{location.slice.inspect}" | ||
| else | ||
| "∅" | ||
| end | ||
| end | ||
| end | ||
| end |
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