Fold VarAlias into Alias

Author: kddnewton

CHANGELOG.md

@@ -11,6 +11,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 - Nodes no longer have a `comments:` keyword on their initializers. By default, they initialize to an empty array. If you were previously passing comments into the initializer, you should now create the node first, then call `node.comments.concat` to add your comments.
 - `IfMod` and `UnlessMod` are no longer nodes. Instead, they have been folded into `If` and `Unless`, respectively. The `If` and `Unless` nodes now have a `modifier?` method to tell you if they were original found in the modifier form.
 - `WhileMod` and `UntilMod` are no longer nodes. Instead, they have been folded into `While` and `Until`, respectively. The `While` and `Until` nodes now have a `modifier?` method to tell you if they were originally found in the modifier form.
+- `VarAlias` is no longer a node. Instead it has been folded into the `Alias` node. The `Alias` node now has a `var_alias?` method to tell you if it is aliasing a global variable.
 
 ## [4.3.0] - 2022-10-28
 

lib/syntax_tree/node.rb

@@ -359,7 +359,7 @@ class Alias < Node
     # Formats an argument to the alias keyword. For symbol literals it uses the
     # value of the symbol directly to look like bare words.
     class AliasArgumentFormatter
-      # [DynaSymbol | SymbolLiteral] the argument being passed to alias
+      # [Backref | DynaSymbol | GVar | SymbolLiteral] the argument being passed to alias
       attr_reader :argument
 
       def initialize(argument)
@@ -383,10 +383,10 @@ def format(q)
       end
     end
 
-    # [DynaSymbol | SymbolLiteral] the new name of the method
+    # [DynaSymbol | GVar | SymbolLiteral] the new name of the method
     attr_reader :left
 
-    # [DynaSymbol | SymbolLiteral] the old name of the method
+    # [Backref | DynaSymbol | GVar | SymbolLiteral] the old name of the method
     attr_reader :right
 
     # [Array[ Comment | EmbDoc ]] the comments attached to this node
@@ -428,6 +428,10 @@ def format(q)
         end
       end
     end
+
+    def var_alias?
+      left.is_a?(GVar)
+    end
   end
 
   # ARef represents when you're pulling a value out of a collection at a
@@ -5399,8 +5403,7 @@ def ternaryable?(statement)
         case statement
         when Alias, Assign, Break, Command, CommandCall, Heredoc, If, IfOp,
              Lambda, MAssign, Next, OpAssign, RescueMod, Return, Return0, Super,
-             Undef, Unless, Until, VarAlias, VoidStmt, While, Yield, Yield0,
-             ZSuper
+             Undef, Unless, Until, VoidStmt, While, Yield, Yield0, ZSuper
           # This is a list of nodes that should not be allowed to be a part of a
           # ternary clause.
           false
@@ -5674,7 +5677,7 @@ def format(q)
       force_flat = [
         Alias, Assign, Break, Command, CommandCall, Heredoc, If, IfOp, Lambda,
         MAssign, Next, OpAssign, RescueMod, Return, Return0, Super, Undef,
-        Unless, VarAlias, VoidStmt, Yield, Yield0, ZSuper
+        Unless, VoidStmt, Yield, Yield0, ZSuper
       ]
 
       if q.parent.is_a?(Paren) || force_flat.include?(truthy.class) ||
@@ -9505,52 +9508,6 @@ def modifier?
     end
   end
 
-  # VarAlias represents when you're using the +alias+ keyword with global
-  # variable arguments.
-  #
-  #     alias $new $old
-  #
-  class VarAlias < Node
-    # [GVar] the new alias of the variable
-    attr_reader :left
-
-    # [Backref | GVar] the current name of the variable to be aliased
-    attr_reader :right
-
-    # [Array[ Comment | EmbDoc ]] the comments attached to this node
-    attr_reader :comments
-
-    def initialize(left:, right:, location:)
-      @left = left
-      @right = right
-      @location = location
-      @comments = []
-    end
-
-    def accept(visitor)
-      visitor.visit_var_alias(self)
-    end
-
-    def child_nodes
-      [left, right]
-    end
-
-    alias deconstruct child_nodes
-
-    def deconstruct_keys(_keys)
-      { left: left, right: right, location: location, comments: comments }
-    end
-
-    def format(q)
-      keyword = "alias "
-
-      q.text(keyword)
-      q.format(left)
-      q.text(" ")
-      q.format(right)
-    end
-  end
-
   # VarField represents a variable that is being assigned a value. As such, it
   # is always a child of an assignment type node.
   #

lib/syntax_tree/parser.rb

@@ -3642,11 +3642,11 @@ def on_until_mod(predicate, statement)
     end
 
     # :call-seq:
-    #   on_var_alias: (GVar left, (Backref | GVar) right) -> VarAlias
+    #   on_var_alias: (GVar left, (Backref | GVar) right) -> Alias
     def on_var_alias(left, right)
       keyword = consume_keyword(:alias)
 
-      VarAlias.new(
+      Alias.new(
         left: left,
         right: right,
         location: keyword.location.to(right.location)

lib/syntax_tree/visitor.rb

@@ -431,9 +431,6 @@ class Visitor < BasicVisitor
     # Visit an Until node.
     alias visit_until visit_child_nodes
 
-    # Visit a VarAlias node.
-    alias visit_var_alias visit_child_nodes
-
     # Visit a VarField node.
     alias visit_var_field visit_child_nodes
 

lib/syntax_tree/visitor/field_visitor.rb

@@ -982,14 +982,6 @@ def visit_until(node)
         end
       end
 
-      def visit_var_alias(node)
-        node(node, "var_alias") do
-          field("left", node.left)
-          field("right", node.right)
-          comments(node)
-        end
-      end
-
       def visit_var_field(node)
         node(node, "var_field") do
           field("value", node.value)

test/node_test.rb

@@ -935,7 +935,7 @@ def test_until_mod
     end
 
     def test_var_alias
-      assert_node(VarAlias, "alias $new $old")
+      assert_node(Alias, "alias $new $old")
     end
 
     def test_var_field