Prepare logical for grouping

Author: charlespwd

lib/liquid/binary_expression.rb

@@ -5,6 +5,11 @@ class BinaryExpression
     attr_reader :operator
     attr_accessor :left_node, :right_node
 
+    # Helper method to simplify right-leaning tree construction
+    def self.rtl(right, operator, left)
+      new(left, operator, right)
+    end
+
     def initialize(left, operator, right)
       @left_node = left
       @operator = operator

lib/liquid/parser.rb

@@ -62,14 +62,11 @@ def expression
     #
     # `a == b and b or c` is evaluated like (a and (b or c))
     def logical
-      expr = equality
-      while (operator = id?('and') || id?('or'))
-        if expr.is_a?(BinaryExpression) && (expr.operator == 'and' || expr.operator == 'or')
-          expr.right_node = BinaryExpression.new(expr.right_node, operator, equality)
-        else
-          expr = BinaryExpression.new(expr, operator, equality)
-        end
-      end
+      operator = nil
+      exprs = [equality]
+      exprs.push(operator, equality) while (operator = id?('and') || id?('or'))
+      expr = exprs.pop
+      expr = BinaryExpression.rtl(expr, exprs.pop, exprs.pop) until exprs.empty?
       expr
     end