Support boolean precedences and nested parentheses

lib/liquid/parser.rb

@@ -60,12 +60,7 @@ def expression
       when :string, :number
         consume
       when :open_round
-        consume
-        first = expression
-        consume(:dotdot)
-        last = expression
-        consume(:close_round)
-        "(#{first}..#{last})"
+        consume_round_parentheses(token)
       else
         raise SyntaxError, "#{token} is not a valid expression"
       end
@@ -79,13 +74,32 @@ def expression
         operator = consume(:boolean_operator)
         left     = expr
         right    = expression
-
-        "#{left} #{operator} #{right}"
+        if look(:close_round)
+          "(#{left} #{operator} #{right})"
+        else
+          "#{left} #{operator} #{right}"
+        end
       else
         expr
       end
     end
 
+    def consume_round_parentheses(token)
+      consume
+      first = expression
+      dotdot_token = consume?(:dotdot)
+      if dotdot_token
+        last = expression
+        consume(:close_round)
+        "(#{first}..#{last})"
+      elsif look(:close_round)
+        consume(:close_round)
+        first
+      else
+        raise SyntaxError, "#{token} is not a valid expression"
+      end
+    end
+
     def argument
       str = +""
       # might be a keyword argument (identifier: expression)

test/test_boolean_helper.rb

@@ -0,0 +1,61 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+module Minitest
+  module Assertions
+    include Liquid
+    def assert_with_lax_parsing(template, expected_output, context = {})
+      prev_error_mode = Liquid::Environment.default.error_mode
+      Liquid::Environment.default.error_mode = :lax
+
+      begin
+        actual_output = Liquid::Template.parse(template).render(context)
+      rescue StandardError => e
+        actual_output = e.message
+      ensure
+        Liquid::Environment.default.error_mode = prev_error_mode
+      end
+
+      assert_equal(expected_output.strip, actual_output.strip)
+    end
+
+    def assert_parity(liquid_expression, expected_result, args = {})
+      assert_condition(liquid_expression, expected_result, args)
+      assert_expression(liquid_expression, expected_result, args)
+    end
+
+    def assert_expression(liquid_expression, expected_result, args = {})
+      assert_parity_scenario(:expression, "{{ #{liquid_expression} }}", expected_result, args)
+    end
+
+    def assert_condition(liquid_condition, expected_result, args = {})
+      assert_parity_scenario(:condition, "{% if #{liquid_condition} %}true{% else %}false{% endif %}", expected_result, args)
+    end
+
+    def assert_parity_scenario(kind, template, exp_output, args = {})
+      act_output = Liquid::Template.parse(template).render(args)
+
+      assert_equal(exp_output, act_output, <<~ERROR_MESSAGE)
+        #{kind.to_s.capitalize} template failure:
+        ---
+        #{template}
+        ---
+        args: #{args.inspect}
+      ERROR_MESSAGE
+    end
+  end
+end
+
+class LinkDrop < Liquid::Drop
+  attr_accessor :levels, :links, :title, :type, :url
+
+  def initialize(levels: nil, links: nil, title: nil, type: nil, url: nil)
+    super()
+
+    @levels = levels
+    @links = links
+    @title = title
+    @type = type
+    @url = url
+  end
+end

test/unit/boolean_precedence_unit_test.rb

@@ -0,0 +1,171 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+require 'test_boolean_helper'
+
+class BooleanPrecedenceUnitTest < Minitest::Test
+  include Liquid
+
+  def test_basic_boolean_parenthesized_expressions
+    assert_parity("false and (false or true)", "false")
+    assert_parity("true and (false or true)", "true")
+    assert_parity("(true and false) or true", "true")
+    assert_parity("(false and true) or false", "false")
+  end
+
+  def test_nested_boolean_parentheses
+    assert_parity("(false and (true or false)) or true", "true")
+    assert_parity("true and (false or (true and true))", "true")
+    assert_parity("(true and (false or false)) or false", "false")
+  end
+
+  def test_multiple_operations_with_consistent_operators
+    assert_parity("(true and true) and (false or true)", "true")
+    assert_parity("(false or false) or (true and false)", "false")
+  end
+
+  def test_parentheses_changing_default_precedence
+    # Default precedence: (true and false) or true
+    assert_parity("true and false or true", "true")
+    # With parentheses: true and (false or true)
+    assert_parity("true and (false or true)", "true")
+
+    # Default precedence: false or (true and true)
+    assert_parity("false or true and true", "true")
+    # With parentheses: (false or true) and true
+    assert_parity("(false or true) and true", "true")
+  end
+
+  def test_boolean_parentheses_with_variables
+    assert_parity("(a or b) and c", "true", { "a" => true, "b" => false, "c" => true })
+    assert_parity("(a or b) and c", "false", { "a" => true, "b" => false, "c" => false })
+    assert_parity("a and (b or c)", "true", { "a" => true, "b" => false, "c" => true })
+    assert_parity("a and (b or c)", "false", { "a" => false, "b" => true, "c" => true })
+  end
+
+  def test_comparison_operators_inside_parentheses
+    assert_parity("(1 > 0) and (2 < 3)", "true")
+    assert_parity("(1 < 0) or (2 > 3)", "false")
+    assert_parity("true and (1 == 1)", "true")
+    assert_parity("false or (2 != 2)", "false")
+  end
+
+  def test_complex_nested_boolean_expressions
+    assert_parity("((true and false) or (false and true)) or ((false or true) and (true or false))", "true")
+    assert_parity("((true and true) or (false and false)) and ((true or false) and (false or true))", "true")
+  end
+
+  def test_not_operator_with_parentheses
+    # Testing how 'not' interacts with parentheses
+    assert_parity("not (true or false)", "false")
+    assert_parity("not (false and true)", "true")
+    assert_parity("(not false) and true", "true")
+    assert_parity("(not true) or false", "false")
+    assert_parity("not (not true)", "true")
+  end
+
+  def test_nil_values_with_boolean_precedence
+    # How nil values interact with boolean expressions and parentheses
+    assert_parity("nil and (true or false)", "false")
+    assert_parity("(nil or true) and false", "false")
+    assert_parity("(nil and nil) or true", "true")
+    assert_parity("true and (nil or false)", "false")
+  end
+
+  def test_mixed_primitive_types_with_parentheses
+    # Testing how different types interact in boolean expressions with parentheses
+    assert_parity("('' or 0) and true", "true")
+    assert_parity("(true and 'string') or false", "true")
+    assert_parity("(false or '') and 1", "false")
+    assert_parity("(nil or false) and 'text'", "false")
+  end
+
+  def test_triple_operator_precedence
+    # Testing three different operators with different parenthesizing
+    assert_parity("true or false and true or false", "true") # default precedence
+    assert_parity("true or (false and true) or false", "true")
+    assert_parity("(true or false) and (true or false)", "true")
+    assert_parity("((true or false) and true) or false", "true")
+    assert_parity("true or (false and (true or false))", "true")
+  end
+
+  def test_undefined_variables_with_parentheses
+    # How undefined variables behave with parentheses
+    assert_parity("(undefined_var or true) and false", "false")
+    assert_parity("true and (undefined_var or false)", "false")
+    assert_parity("(undefined_var and true) or true", "true")
+    assert_parity("false or (undefined_var and false)", "false")
+  end
+
+  def test_comparison_chaining_with_parentheses
+    # Testing how comparison chains work with parentheses
+    assert_parity("(1 < 2) and (2 < 3) and (3 < 4)", "true")
+    assert_parity("(1 < 2) and ((2 > 3) or (3 < 4))", "true")
+    assert_parity(
+      "(a > b) or ((c < d) and (e == f))",
+      "true",
+      { "a" => 5, "b" => 3, "c" => 1, "d" => 2, "e" => 7, "f" => 7 },
+    )
+    assert_parity(
+      "(a > b) or ((c < d) and (e == f))",
+      "false",
+      { "a" => 3, "b" => 5, "c" => 2, "d" => 1, "e" => 7, "f" => 8 },
+    )
+  end
+
+  def test_deeply_nested_expressions
+    # Testing very deep nesting to ensure parser handles it correctly
+    assert_parity("(((true and true) or (false and false)) and ((true or false) and (true)))", "true")
+    assert_parity(
+      "(((a or b) and c) or (d and (e or f)))",
+      "true",
+      { "a" => false, "b" => true, "c" => true, "d" => true, "e" => true, "f" => false },
+    )
+  end
+
+  def test_malformed_parentheses
+    # Unbalanced parentheses - missing closing parenthesis
+    template = "{% if (true and false %}true{% else %}false{% endif %}"
+    assert_raises(Liquid::SyntaxError) { Liquid::Template.parse(template) }
+
+    # Unbalanced parentheses - missing opening parenthesis
+    template = "{% if true and false) %}true{% else %}false{% endif %}"
+    assert_raises(Liquid::SyntaxError) { Liquid::Template.parse(template) }
+
+    # Empty parentheses
+    template = "{% if () %}true{% else %}false{% endif %}"
+    assert_raises(Liquid::SyntaxError) { Liquid::Template.parse(template) }
+
+    # Consecutive opening parentheses without operators
+    template = "{% if ((true) %}true{% else %}false{% endif %}"
+    assert_raises(Liquid::SyntaxError) { Liquid::Template.parse(template) }
+
+    # Consecutive closing parentheses without proper opening
+    template = "{% if (true)) %}true{% else %}false{% endif %}"
+    assert_raises(Liquid::SyntaxError) { Liquid::Template.parse(template) }
+
+    # Parentheses with missing operand
+    template = "{% if (and true) %}true{% else %}false{% endif %}"
+    assert_raises(Liquid::SyntaxError) { Liquid::Template.parse(template) }
+
+    # Operator followed immediately by closing parenthesis
+    template = "{% if (true and) %}true{% else %}false{% endif %}"
+    assert_raises(Liquid::SyntaxError) { Liquid::Template.parse(template) }
+
+    # Nested malformed parentheses
+    template = "{% if (true and (false or true) %}true{% else %}false{% endif %}"
+    assert_raises(Liquid::SyntaxError) { Liquid::Template.parse(template) }
+
+    # Double parentheses with no content between them
+    template = "{% if true and (()) %}true{% else %}false{% endif %}"
+    assert_raises(Liquid::SyntaxError) { Liquid::Template.parse(template) }
+
+    # Misplaced parentheses around operators
+    template = "{% if true (and) false %}true{% else %}false{% endif %}"
+    assert_raises(Liquid::SyntaxError) { Liquid::Template.parse(template) }
+
+    # Parentheses at wrong position in expression
+    template = "{% if true) and (false %}true{% else %}false{% endif %}"
+    assert_raises(Liquid::SyntaxError) { Liquid::Template.parse(template) }
+  end
+end

test/unit/boolean_unit_test.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require 'test_helper'
+require 'test_boolean_helper'
 
 class BooleanUnitTest < Minitest::Test
   include Liquid
@@ -487,60 +488,4 @@ def test_assign_boolean_expression_to_variable
     template = Liquid::Template.parse("{% assign is_preview_mode = content_for_header contains 'foo' or content_for_header contains 'bar' %}{{ is_preview_mode }}")
     assert_equal("false", template.render(context))
   end
-
-  private
-
-  def assert_with_lax_parsing(template, expected_output, context = {})
-    prev_error_mode = Liquid::Environment.default.error_mode
-    Liquid::Environment.default.error_mode = :lax
-
-    begin
-      actual_output = Liquid::Template.parse(template).render(context)
-    rescue StandardError => e
-      actual_output = e.message
-    ensure
-      Liquid::Environment.default.error_mode = prev_error_mode
-    end
-
-    assert_equal(expected_output.strip, actual_output.strip)
-  end
-
-  def assert_parity(liquid_expression, expected_result, args = {})
-    assert_condition(liquid_expression, expected_result, args)
-    assert_expression(liquid_expression, expected_result, args)
-  end
-
-  def assert_expression(liquid_expression, expected_result, args = {})
-    assert_parity_scenario(:expression, "{{ #{liquid_expression} }}", expected_result, args)
-  end
-
-  def assert_condition(liquid_condition, expected_result, args = {})
-    assert_parity_scenario(:condition, "{% if #{liquid_condition} %}true{% else %}false{% endif %}", expected_result, args)
-  end
-
-  def assert_parity_scenario(kind, template, exp_output, args = {})
-    act_output = Liquid::Template.parse(template).render(args)
-
-    assert_equal(exp_output, act_output, <<~ERROR_MESSAGE)
-      #{kind.to_s.capitalize} template failure:
-      ---
-      #{template}
-      ---
-      args: #{args.inspect}
-    ERROR_MESSAGE
-  end
-
-  class LinkDrop < Liquid::Drop
-    attr_accessor :levels, :links, :title, :type, :url
-
-    def initialize(levels: nil, links: nil, title: nil, type: nil, url: nil)
-      super()
-
-      @levels = levels
-      @links = links
-      @title = title
-      @type = type
-      @url = url
-    end
-  end
 end