testsyntacticpredicateevaluation.rb

antlr最新版本V3源代码

# [The "BSD licence"]
# Copyright (c) 2005 Martin Traverso
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require 'test/unit'
require 'antlr'

class TestSyntacticPredicateEvaluation < Test::Unit::TestCase

    def test_two_preds_with_naked_alt
        grammar = <<-END
	        s returns [result]
	        @init { @out = "" }: (a ';')+ { result = @out };

    			a
    			options {
    			  k=1;
    			}
    			:
    			  (b '.')=> b '.' { @out << "[alt 1]" }
    			| (b)=> b { @out << "[alt 2]" }
    			| c       { @out << "[alt 3]" }
    			  ;

    			b
    			@init { @out << "[enter b]" }
    			   : '(' 'x' ')' ;

    			c
    			@init { @out << "[enter c]" }
    			   : '(' c ')' | 'x' ;

    			WS : (' '|'\\n')+ { channel = 99 }
    			   ;
	    END

		  parser = Grammar::compile(grammar, "s")

      assert_equal("[enter b][enter b][enter b][alt 2]", parser.parse('(x) ;'))
      assert_equal("[enter b][enter b][alt 1]", parser.parse('(x). ;'))
	    assert_equal("[enter b][enter b][enter c][enter c][enter c][alt 3]", parser.parse('((x)) ;'))
    end

    def test_two_preds_with_naked_alt_not_last
        grammar = <<-END
          s returns [result]
          @init { @out = "" }: (a ';')+ { result = @out };

    			a
    			options {
    			  k=1;
    			}
    			  : (b '.')=> b '.' { @out << "[alt 1]" }
    			  | c       { @out << "[alt 2]" }
    			  | (b)=> b { @out << "[alt 3]" }
    			  ;
    			b
    			@init { @out << "[enter b]" }
    			   : '(' 'x' ')' ;
    			c
    			@init { @out << "[enter c]" }
    			   : '(' c ')' | 'x' ;
    			WS : (' '|'\\n')+ {channel=99}
    			   ;
	    END

		  parser = Grammar::compile(grammar, "s")

	    assert_equal("[enter b][enter c][enter c][alt 2]", parser.parse("(x) ;"))
	    assert_equal("[enter b][enter b][alt 1]", parser.parse("(x). ;"))
	    assert_equal("[enter b][enter c][enter c][enter c][alt 2]", parser.parse("((x)) ;"))
    end

    def test_lexer_pred
        Object::const_set('OUT', [])
        grammar = <<-END
            s returns [result]
            @init { OUT.clear }: A { result = OUT.join };

			A options {k=1;}
			  : (B '.')=>B '.' { OUT << "alt1" }
			  | B { OUT << "alt2" }
			  ;

			fragment
			B : 'x'+ ;
	    END

		  parser = Grammar::compile(grammar, "s")

	    assert_equal("alt2", parser.parse('xxx'))
	    assert_equal("alt1", parser.parse('xxx.'))
    end
end