[ruby/prism] Speed up creating Ruby AST

When creating the Ruby AST, we were previously allocating Location
objects for every node and every inner location. Instead, this
commit changes it to pack both the start offset and length into a
single u64 and pass that into the nodes. Then, when the locations
are requested via a reader method, we lazily allocate the Location
objects.

https://github.com/ruby/prism/commit/de203dca83

Co-Authored-By: Aaron Patterson <tenderlove@ruby-lang.org>

3 files changed, 238 insertions, 85 deletions

diff --git a/lib/prism/desugar_compiler.rb b/lib/prism/desugar_compiler.rb
index daca02f35e..00b3097f9f 100644
--- a/lib/prism/desugar_compiler.rb
+++ b/lib/prism/desugar_compiler.rb
@@ -1,6 +1,216 @@
 # frozen_string_literal: true
 
 module Prism
+  class DesugarAndWriteNode # :nodoc:
+    attr_reader :node, :source, :read_class, :write_class, :arguments
+
+    def initialize(node, source, read_class, write_class, *arguments)
+      @node = node
+      @source = source
+      @read_class = read_class
+      @write_class = write_class
+      @arguments = arguments
+    end
+
+    # Desugar `x &&= y` to `x && x = y`
+    def compile
+      AndNode.new(
+        source,
+        read_class.new(source, *arguments, node.name_loc),
+        write_class.new(source, *arguments, node.name_loc, node.value, node.operator_loc, node.location),
+        node.operator_loc,
+        node.location
+      )
+    end
+  end
+
+  class DesugarOrWriteDefinedNode # :nodoc:
+    attr_reader :node, :source, :read_class, :write_class, :arguments
+
+    def initialize(node, source, read_class, write_class, *arguments)
+      @node = node
+      @source = source
+      @read_class = read_class
+      @write_class = write_class
+      @arguments = arguments
+    end
+
+    # Desugar `x ||= y` to `defined?(x) ? x : x = y`
+    def compile
+      IfNode.new(
+        source,
+        node.operator_loc,
+        DefinedNode.new(source, nil, read_class.new(source, *arguments, node.name_loc), nil, node.operator_loc, node.name_loc),
+        node.operator_loc,
+        StatementsNode.new(source, [read_class.new(source, *arguments, node.name_loc)], node.location),
+        ElseNode.new(
+          source,
+          node.operator_loc,
+          StatementsNode.new(
+            source,
+            [write_class.new(source, *arguments, node.name_loc, node.value, node.operator_loc, node.location)],
+            node.location
+          ),
+          node.operator_loc,
+          node.location
+        ),
+        node.operator_loc,
+        node.location
+      )
+    end
+  end
+
+  class DesugarOperatorWriteNode # :nodoc:
+    attr_reader :node, :source, :read_class, :write_class, :arguments
+
+    def initialize(node, source, read_class, write_class, *arguments)
+      @node = node
+      @source = source
+      @read_class = read_class
+      @write_class = write_class
+      @arguments = arguments
+    end
+
+    # Desugar `x += y` to `x = x + y`
+    def compile
+      write_class.new(
+        source,
+        *arguments,
+        node.name_loc,
+        CallNode.new(
+          source,
+          0,
+          read_class.new(source, *arguments, node.name_loc),
+          nil,
+          node.operator_loc.slice.chomp("="),
+          node.operator_loc.copy(length: node.operator_loc.length - 1),
+          nil,
+          ArgumentsNode.new(source, 0, [node.value], node.value.location),
+          nil,
+          nil,
+          node.location
+        ),
+        node.operator_loc.copy(start_offset: node.operator_loc.end_offset - 1, length: 1),
+        node.location
+      )
+    end
+  end
+
+  class DesugarOrWriteNode # :nodoc:
+    attr_reader :node, :source, :read_class, :write_class, :arguments
+
+    def initialize(node, source, read_class, write_class, *arguments)
+      @node = node
+      @source = source
+      @read_class = read_class
+      @write_class = write_class
+      @arguments = arguments
+    end
+
+    # Desugar `x ||= y` to `x || x = y`
+    def compile
+      OrNode.new(
+        source,
+        read_class.new(source, *arguments, node.name_loc),
+        write_class.new(source, *arguments, node.name_loc, node.value, node.operator_loc, node.location),
+        node.operator_loc,
+        node.location
+      )
+    end
+  end
+
+  private_constant :DesugarAndWriteNode, :DesugarOrWriteNode, :DesugarOrWriteDefinedNode, :DesugarOperatorWriteNode
+
+  class ClassVariableAndWriteNode
+    def desugar # :nodoc:
+      DesugarAndWriteNode.new(self, source, ClassVariableReadNode, ClassVariableWriteNode, name).compile
+    end
+  end
+
+  class ClassVariableOrWriteNode
+    def desugar # :nodoc:
+      DesugarOrWriteDefinedNode.new(self, source, ClassVariableReadNode, ClassVariableWriteNode, name).compile
+    end
+  end
+
+  class ClassVariableOperatorWriteNode
+    def desugar # :nodoc:
+      DesugarOperatorWriteNode.new(self, source, ClassVariableReadNode, ClassVariableWriteNode, name).compile
+    end
+  end
+
+  class ConstantAndWriteNode
+    def desugar # :nodoc:
+      DesugarAndWriteNode.new(self, source, ConstantReadNode, ConstantWriteNode, name).compile
+    end
+  end
+
+  class ConstantOrWriteNode
+    def desugar # :nodoc:
+      DesugarOrWriteDefinedNode.new(self, source, ConstantReadNode, ConstantWriteNode, name).compile
+    end
+  end
+
+  class ConstantOperatorWriteNode
+    def desugar # :nodoc:
+      DesugarOperatorWriteNode.new(self, source, ConstantReadNode, ConstantWriteNode, name).compile
+    end
+  end
+
+  class GlobalVariableAndWriteNode
+    def desugar # :nodoc:
+      DesugarAndWriteNode.new(self, source, GlobalVariableReadNode, GlobalVariableWriteNode, name).compile
+    end
+  end
+
+  class GlobalVariableOrWriteNode
+    def desugar # :nodoc:
+      DesugarOrWriteDefinedNode.new(self, source, GlobalVariableReadNode, GlobalVariableWriteNode, name).compile
+    end
+  end
+
+  class GlobalVariableOperatorWriteNode
+    def desugar # :nodoc:
+      DesugarOperatorWriteNode.new(self, source, GlobalVariableReadNode, GlobalVariableWriteNode, name).compile
+    end
+  end
+
+  class InstanceVariableAndWriteNode
+    def desugar # :nodoc:
+      DesugarAndWriteNode.new(self, source, InstanceVariableReadNode, InstanceVariableWriteNode, name).compile
+    end
+  end
+
+  class InstanceVariableOrWriteNode
+    def desugar # :nodoc:
+      DesugarOrWriteNode.new(self, source, InstanceVariableReadNode, InstanceVariableWriteNode, name).compile
+    end
+  end
+
+  class InstanceVariableOperatorWriteNode
+    def desugar # :nodoc:
+      DesugarOperatorWriteNode.new(self, source, InstanceVariableReadNode, InstanceVariableWriteNode, name).compile
+    end
+  end
+
+  class LocalVariableAndWriteNode
+    def desugar # :nodoc:
+      DesugarAndWriteNode.new(self, source, LocalVariableReadNode, LocalVariableWriteNode, name, depth).compile
+    end
+  end
+
+  class LocalVariableOrWriteNode
+    def desugar # :nodoc:
+      DesugarOrWriteNode.new(self, source, LocalVariableReadNode, LocalVariableWriteNode, name, depth).compile
+    end
+  end
+
+  class LocalVariableOperatorWriteNode
+    def desugar # :nodoc:
+      DesugarOperatorWriteNode.new(self, source, LocalVariableReadNode, LocalVariableWriteNode, name, depth).compile
+    end
+  end
+
   # DesugarCompiler is a compiler that desugars Ruby code into a more primitive
   # form. This is useful for consumers that want to deal with fewer node types.
   class DesugarCompiler < MutationCompiler
@@ -10,7 +220,7 @@ module Prism
     #
     # @@foo && @@foo = bar
     def visit_class_variable_and_write_node(node)
-      desugar_and_write_node(node, ClassVariableReadNode, ClassVariableWriteNode, node.name)
+      node.desugar
     end
 
     # @@foo ||= bar
@@ -19,7 +229,7 @@ module Prism
     #
     # defined?(@@foo) ? @@foo : @@foo = bar
     def visit_class_variable_or_write_node(node)
-      desugar_or_write_defined_node(node, ClassVariableReadNode, ClassVariableWriteNode, node.name)
+      node.desugar
     end
 
     # @@foo += bar
@@ -28,7 +238,7 @@ module Prism
     #
     # @@foo = @@foo + bar
     def visit_class_variable_operator_write_node(node)
-      desugar_operator_write_node(node, ClassVariableReadNode, ClassVariableWriteNode, node.name)
+      node.desugar
     end
 
     # Foo &&= bar
@@ -37,7 +247,7 @@ module Prism
     #
     # Foo && Foo = bar
     def visit_constant_and_write_node(node)
-      desugar_and_write_node(node, ConstantReadNode, ConstantWriteNode, node.name)
+      node.desugar
     end
 
     # Foo ||= bar
@@ -46,7 +256,7 @@ module Prism
     #
     # defined?(Foo) ? Foo : Foo = bar
     def visit_constant_or_write_node(node)
-      desugar_or_write_defined_node(node, ConstantReadNode, ConstantWriteNode, node.name)
+      node.desugar
     end
 
     # Foo += bar
@@ -55,7 +265,7 @@ module Prism
     #
     # Foo = Foo + bar
     def visit_constant_operator_write_node(node)
-      desugar_operator_write_node(node, ConstantReadNode, ConstantWriteNode, node.name)
+      node.desugar
     end
 
     # $foo &&= bar
@@ -64,7 +274,7 @@ module Prism
     #
     # $foo && $foo = bar
     def visit_global_variable_and_write_node(node)
-      desugar_and_write_node(node, GlobalVariableReadNode, GlobalVariableWriteNode, node.name)
+      node.desugar
     end
 
     # $foo ||= bar
@@ -73,7 +283,7 @@ module Prism
     #
     # defined?($foo) ? $foo : $foo = bar
     def visit_global_variable_or_write_node(node)
-      desugar_or_write_defined_node(node, GlobalVariableReadNode, GlobalVariableWriteNode, node.name)
+      node.desugar
     end
 
     # $foo += bar
@@ -82,7 +292,7 @@ module Prism
     #
     # $foo = $foo + bar
     def visit_global_variable_operator_write_node(node)
-      desugar_operator_write_node(node, GlobalVariableReadNode, GlobalVariableWriteNode, node.name)
+      node.desugar
     end
 
     # @foo &&= bar
@@ -91,7 +301,7 @@ module Prism
     #
     # @foo && @foo = bar
     def visit_instance_variable_and_write_node(node)
-      desugar_and_write_node(node, InstanceVariableReadNode, InstanceVariableWriteNode, node.name)
+      node.desugar
     end
 
     # @foo ||= bar
@@ -100,7 +310,7 @@ module Prism
     #
     # @foo || @foo = bar
     def visit_instance_variable_or_write_node(node)
-      desugar_or_write_node(node, InstanceVariableReadNode, InstanceVariableWriteNode, node.name)
+      node.desugar
     end
 
     # @foo += bar
@@ -109,7 +319,7 @@ module Prism
     #
     # @foo = @foo + bar
     def visit_instance_variable_operator_write_node(node)
-      desugar_operator_write_node(node, InstanceVariableReadNode, InstanceVariableWriteNode, node.name)
+      node.desugar
     end
 
     # foo &&= bar
@@ -118,7 +328,7 @@ module Prism
     #
     # foo && foo = bar
     def visit_local_variable_and_write_node(node)
-      desugar_and_write_node(node, LocalVariableReadNode, LocalVariableWriteNode, node.name, node.depth)
+      node.desugar
     end
 
     # foo ||= bar
@@ -127,7 +337,7 @@ module Prism
     #
     # foo || foo = bar
     def visit_local_variable_or_write_node(node)
-      desugar_or_write_node(node, LocalVariableReadNode, LocalVariableWriteNode, node.name, node.depth)
+      node.desugar
     end
 
     # foo += bar
@@ -136,72 +346,7 @@ module Prism
     #
     # foo = foo + bar
     def visit_local_variable_operator_write_node(node)
-      desugar_operator_write_node(node, LocalVariableReadNode, LocalVariableWriteNode, node.name, node.depth)
-    end
-
-    private
-
-    # Desugar `x &&= y` to `x && x = y`
-    def desugar_and_write_node(node, read_class, write_class, *arguments)
-      AndNode.new(
-        read_class.new(*arguments, node.name_loc),
-        write_class.new(*arguments, node.name_loc, node.value, node.operator_loc, node.location),
-        node.operator_loc,
-        node.location
-      )
-    end
-
-    # Desugar `x += y` to `x = x + y`
-    def desugar_operator_write_node(node, read_class, write_class, *arguments)
-      write_class.new(
-        *arguments,
-        node.name_loc,
-        CallNode.new(
-          0,
-          read_class.new(*arguments, node.name_loc),
-          nil,
-          node.operator_loc.slice.chomp("="),
-          node.operator_loc.copy(length: node.operator_loc.length - 1),
-          nil,
-          ArgumentsNode.new(0, [node.value], node.value.location),
-          nil,
-          nil,
-          node.location
-        ),
-        node.operator_loc.copy(start_offset: node.operator_loc.end_offset - 1, length: 1),
-        node.location
-      )
-    end
-
-    # Desugar `x ||= y` to `x || x = y`
-    def desugar_or_write_node(node, read_class, write_class, *arguments)
-      OrNode.new(
-        read_class.new(*arguments, node.name_loc),
-        write_class.new(*arguments, node.name_loc, node.value, node.operator_loc, node.location),
-        node.operator_loc,
-        node.location
-      )
-    end
-
-    # Desugar `x ||= y` to `defined?(x) ? x : x = y`
-    def desugar_or_write_defined_node(node, read_class, write_class, *arguments)
-      IfNode.new(
-        node.operator_loc,
-        DefinedNode.new(nil, read_class.new(*arguments, node.name_loc), nil, node.operator_loc, node.name_loc),
-        node.operator_loc,
-        StatementsNode.new([read_class.new(*arguments, node.name_loc)], node.location),
-        ElseNode.new(
-          node.operator_loc,
-          StatementsNode.new(
-            [write_class.new(*arguments, node.name_loc, node.value, node.operator_loc, node.location)],
-            node.location
-          ),
-          node.operator_loc,
-          node.location
-        ),
-        node.operator_loc,
-        node.location
-      )
+      node.desugar
     end
   end
 end
diff --git a/lib/prism/parse_result.rb b/lib/prism/parse_result.rb
index bcebc1a437..5b22184ef1 100644
--- a/lib/prism/parse_result.rb
+++ b/lib/prism/parse_result.rb
@@ -452,17 +452,19 @@ module Prism
 
   # This represents a token from the Ruby source.
   class Token
+    # The Source object that represents the source this token came from.
+    attr_reader :source
+    private :source
+
     # The type of token that this token is.
     attr_reader :type
 
     # A byteslice of the source that this token represents.
     attr_reader :value
 
-    # A Location object representing the location of this token in the source.
-    attr_reader :location
-
     # Create a new token object with the given type, value, and location.
-    def initialize(type, value, location)
+    def initialize(source, type, value, location)
+      @source = source
       @type = type
       @value = value
       @location = location
@@ -473,6 +475,12 @@ module Prism
       { type: type, value: value, location: location }
     end
 
+    # A Location object representing the location of this token in the source.
+    def location
+      return @location if @location.is_a?(Location)
+      @location = Location.new(source, @location >> 32, @location & 0xFFFFFFFF)
+    end
+
     # Implement the pretty print interface for Token.
     def pretty_print(q)
       q.group do
diff --git a/lib/prism/translation/parser/compiler.rb b/lib/prism/translation/parser/compiler.rb
index 264d85c261..81156a64c7 100644
--- a/lib/prism/translation/parser/compiler.rb
+++ b/lib/prism/translation/parser/compiler.rb
@@ -1477,7 +1477,7 @@ module Prism
         # ^^^^^
         def visit_string_node(node)
           if node.opening&.start_with?("<<")
-            children, closing = visit_heredoc(InterpolatedStringNode.new(node.opening_loc, [node.copy(opening_loc: nil, closing_loc: nil, location: node.content_loc)], node.closing_loc, node.location))
+            children, closing = visit_heredoc(InterpolatedStringNode.new(node.send(:source), node.opening_loc, [node.copy(opening_loc: nil, closing_loc: nil, location: node.content_loc)], node.closing_loc, node.location))
             builder.string_compose(token(node.opening_loc), children, closing)
           elsif node.opening == "?"
             builder.character([node.unescaped, srange(node.location)])