Add option legacy file which will load removed constants

lib/liquid/legacy.rb

@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+module Liquid
+  FilterSeparator = FILTER_SEPARATOR
+  ArgumentSeparator = ARGUMENT_SEPARATOR
+  FilterArgumentSeparator = FILTER_ARGUMENT_SEPARATOR
+  VariableAttributeSeparator = VARIABLE_ATTRIBUTE_SEPARATOR
+  WhitespaceControl = WHITESPACE_CONTROL
+  TagStart = TAG_START
+  TagEnd = TAG_END
+  VariableSignature = VARIABLE_SIGNATURE
+  VariableSegment = VARIABLE_SEGMENT
+  VariableStart = VARIABLE_START
+  VariableEnd = VARIABLE_END
+  VariableIncompleteEnd = VARIABLE_INCOMPLETE_END
+  QuotedString = QUOTED_STRING
+  QuotedFragment = QUOTED_FRAGMENT
+  TagAttributes = TAG_ATTRIBUTES
+  AnyStartingTag = ANY_STARTING_TAG
+  PartialTemplateParser = PARTIAL_TEMPLATE_PARSER
+  TemplateParser = TEMPLATE_PARSER
+  VariableParser = VARIABLE_PARSER
+
+  class BlockBody
+    FullToken = FULL_TOKEN
+    ContentOfVariable = CONTENT_OF_VARIABLE
+    WhitespaceOrNothing = WHITESPACE_OR_NOTHING
+    TAGSTART = TAG_START
+    VARSTART = VAR_START
+  end
+
+  class Assign < Tag
+    Syntax = SYNTAX
+  end
+
+  class Capture < Block
+    Syntax = SYNTAX
+  end
+
+  class Case < Block
+    Syntax     = SYNTAX
+    WhenSyntax = WHEN_SYNTAX
+  end
+
+  class Cycle < Tag
+    SimpleSyntax = SIMPLE_SYNTAX
+    NamedSyntax  = NAMED_SYNTAX
+  end
+
+  class For < Block
+    Syntax = SYNTAX
+  end
+
+  class If < Block
+    Syntax = SYNTAX
+    ExpressionsAndOperators = EXPRESSIONS_AND_OPERATORS
+  end
+
+  class Include < Tag
+    Syntax = SYNTAX
+  end
+
+  class Raw < Block
+    Syntax = SYNTAX
+    FullTokenPossiblyInvalid = FULL_TOKEN_POSSIBLY_INVALID
+  end
+
+  class TableRow < Block
+    Syntax = SYNTAX
+  end
+
+  class Variable
+    FilterMarkupRegex = FILTER_MARKUP_REGEX
+    FilterParser = FILTER_PARSER
+    FilterArgsRegex = FILTER_ARGS_REGEX
+    JustTagAttributes = JUST_TAG_ATTRIBUTES
+    MarkupWithQuotedFragment = MARKUP_WITH_QUOTED_FRAGMENT
+  end
+end

test/integration/legacy_test.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+require 'liquid/legacy'
+
+class FiltersTest < Minitest::Test
+  include Liquid
+
+  def test_constants
+    assert_equal Liquid::FilterSeparator, Liquid::FILTER_SEPARATOR
+    assert_equal Liquid::BlockBody::ContentOfVariable, Liquid::BlockBody::CONTENT_OF_VARIABLE
+  end
+end