[ruby/yarp] Split up compiler versus visitor

2e6baa3f19

lib/yarp/desugar_compiler.rb

@@ -0,0 +1,204 @@
+# frozen_string_literal: true
+
+module YARP
+  class DesugarCompiler < MutationCompiler
+    # @@foo &&= bar
+    #
+    # becomes
+    #
+    # @@foo && @@foo = bar
+    def visit_class_variable_and_write_node(node)
+      desugar_and_write_node(node, ClassVariableReadNode, ClassVariableWriteNode, node.name)
+    end
+
+    # @@foo ||= bar
+    #
+    # becomes
+    #
+    # defined?(@@foo) ? @@foo : @@foo = bar
+    def visit_class_variable_or_write_node(node)
+      desugar_or_write_defined_node(node, ClassVariableReadNode, ClassVariableWriteNode, node.name)
+    end
+
+    # @@foo += bar
+    #
+    # becomes
+    #
+    # @@foo = @@foo + bar
+    def visit_class_variable_operator_write_node(node)
+      desugar_operator_write_node(node, ClassVariableReadNode, ClassVariableWriteNode, node.name)
+    end
+
+    # Foo &&= bar
+    #
+    # becomes
+    #
+    # Foo && Foo = bar
+    def visit_constant_and_write_node(node)
+      desugar_and_write_node(node, ConstantReadNode, ConstantWriteNode, node.name)
+    end
+
+    # Foo ||= bar
+    #
+    # becomes
+    #
+    # defined?(Foo) ? Foo : Foo = bar
+    def visit_constant_or_write_node(node)
+      desugar_or_write_defined_node(node, ConstantReadNode, ConstantWriteNode, node.name)
+    end
+
+    # Foo += bar
+    #
+    # becomes
+    #
+    # Foo = Foo + bar
+    def visit_constant_operator_write_node(node)
+      desugar_operator_write_node(node, ConstantReadNode, ConstantWriteNode, node.name)
+    end
+
+    # $foo &&= bar
+    #
+    # becomes
+    #
+    # $foo && $foo = bar
+    def visit_global_variable_and_write_node(node)
+      desugar_and_write_node(node, GlobalVariableReadNode, GlobalVariableWriteNode, node.name)
+    end
+
+    # $foo ||= bar
+    #
+    # becomes
+    #
+    # defined?($foo) ? $foo : $foo = bar
+    def visit_global_variable_or_write_node(node)
+      desugar_or_write_defined_node(node, GlobalVariableReadNode, GlobalVariableWriteNode, node.name)
+    end
+
+    # $foo += bar
+    #
+    # becomes
+    #
+    # $foo = $foo + bar
+    def visit_global_variable_operator_write_node(node)
+      desugar_operator_write_node(node, GlobalVariableReadNode, GlobalVariableWriteNode, node.name)
+    end
+
+    # @foo &&= bar
+    #
+    # becomes
+    #
+    # @foo && @foo = bar
+    def visit_instance_variable_and_write_node(node)
+      desugar_and_write_node(node, InstanceVariableReadNode, InstanceVariableWriteNode, node.name)
+    end
+
+    # @foo ||= bar
+    #
+    # becomes
+    #
+    # @foo || @foo = bar
+    def visit_instance_variable_or_write_node(node)
+      desugar_or_write_node(node, InstanceVariableReadNode, InstanceVariableWriteNode, node.name)
+    end
+
+    # @foo += bar
+    #
+    # becomes
+    #
+    # @foo = @foo + bar
+    def visit_instance_variable_operator_write_node(node)
+      desugar_operator_write_node(node, InstanceVariableReadNode, InstanceVariableWriteNode, node.name)
+    end
+
+    # foo &&= bar
+    #
+    # becomes
+    #
+    # foo && foo = bar
+    def visit_local_variable_and_write_node(node)
+      desugar_and_write_node(node, LocalVariableReadNode, LocalVariableWriteNode, node.name, node.depth)
+    end
+
+    # foo ||= bar
+    #
+    # becomes
+    #
+    # foo || foo = bar
+    def visit_local_variable_or_write_node(node)
+      desugar_or_write_node(node, LocalVariableReadNode, LocalVariableWriteNode, node.name, node.depth)
+    end
+
+    # foo += bar
+    #
+    # becomes
+    #
+    # 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(
+          read_class.new(*arguments, node.name_loc),
+          nil,
+          node.operator_loc.copy(length: node.operator_loc.length - 1),
+          nil,
+          ArgumentsNode.new([node.value], node.value.location),
+          nil,
+          nil,
+          0,
+          node.operator_loc.slice.chomp("="),
+          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),
+        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
+      )
+    end
+  end
+end