testsyntacticpredicateevaluation.java

ANTLR(ANother Tool for Language Recognition)它是这样的一种工具

/*
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Copyright (c) 2005-2006 Terence Parr
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package org.antlr.test;

public class TestSyntacticPredicateEvaluation extends BaseTest {
	public void testTwoPredsWithNakedAlt() throws Exception {
		String grammar =
			"grammar t;\n" +
			"s : (a ';')+ ;\n" +
			"a\n" +
			"options {\n" +
			"  k=1;\n" +
			"}\n" +
			"  : (b '.')=> b '.' {System.out.println(\"alt 1\");}\n" +
			"  | (b)=> b {System.out.println(\"alt 2\");}\n" +
			"  | c       {System.out.println(\"alt 3\");}\n" +
			"  ;\n" +
			"b\n" +
			"@init {System.out.println(\"enter b\");}\n" +
			"   : '(' 'x' ')' ;\n" +
			"c\n" +
			"@init {System.out.println(\"enter c\");}\n" +
			"   : '(' c ')' | 'x' ;\n" +
			"WS : (' '|'\\n')+ {channel=99;}\n" +
			"   ;\n" ;
		String found = execParser("t.g", grammar, "tParser", "tLexer",
				    "a", "(x) ;", false);
		String expecting =
			"enter b\n" +
			"enter b\n" +
			"enter b\n" +
			"alt 2\n";
		assertEquals(expecting, found);

		found = execParser("t.g", grammar, "tParser", "tLexer",
			    "a", "(x). ;", false);
		expecting =
			"enter b\n" +
			"enter b\n" +
			"alt 1\n";
		assertEquals(expecting, found);

		found = execParser("t.g", grammar, "tParser", "tLexer",
			    "a", "((x)) ;", false);
		expecting =
			"enter b\n" +
			"enter b\n" +
			"enter c\n" +
			"enter c\n" +
			"enter c\n" +
			"alt 3\n";
		assertEquals(expecting, found);
	}

	public void testTwoPredsWithNakedAltNotLast() throws Exception {
		String grammar =
			"grammar t;\n" +
			"s : (a ';')+ ;\n" +
			"a\n" +
			"options {\n" +
			"  k=1;\n" +
			"}\n" +
			"  : (b '.')=> b '.' {System.out.println(\"alt 1\");}\n" +
			"  | c       {System.out.println(\"alt 2\");}\n" +
			"  | (b)=> b {System.out.println(\"alt 3\");}\n" +
			"  ;\n" +
			"b\n" +
			"@init {System.out.println(\"enter b\");}\n" +
			"   : '(' 'x' ')' ;\n" +
			"c\n" +
			"@init {System.out.println(\"enter c\");}\n" +
			"   : '(' c ')' | 'x' ;\n" +
			"WS : (' '|'\\n')+ {channel=99;}\n" +
			"   ;\n" ;
		String found = execParser("t.g", grammar, "tParser", "tLexer",
				    "a", "(x) ;", false);
		String expecting =
			"enter b\n" +
			"enter c\n" +
			"enter c\n" +
			"alt 2\n";
		assertEquals(expecting, found);

		found = execParser("t.g", grammar, "tParser", "tLexer",
			    "a", "(x). ;", false);
		expecting =
			"enter b\n" +
			"enter b\n" +
			"alt 1\n";
		assertEquals(expecting, found);

		found = execParser("t.g", grammar, "tParser", "tLexer",
			    "a", "((x)) ;", false);
		expecting =
			"enter b\n" +
			"enter c\n" +
			"enter c\n" +
			"enter c\n" +
			"alt 2\n";
		assertEquals(expecting, found);
	}

	public void testLexerPred() throws Exception {
		String grammar =
			"grammar t;\n" +
			"s : A ;\n" +
			"A options {k=1;}\n" + // force backtracking
			"  : (B '.')=>B '.' {System.out.println(\"alt1\");}\n" +
			"  | B {System.out.println(\"alt2\");}" +
			"  ;\n" +
			"fragment\n" +
			"B : 'x'+ ;\n" ;
		String found = execParser("t.g", grammar, "tParser", "tLexer",
				    "s", "xxx", false);

		assertEquals("alt2\n", found);

		found = execParser("t.g", grammar, "tParser", "tLexer",
			    "s", "xxx.", false);

		assertEquals("alt1\n", found);
	}

	public void testLexerPredCyclicPrediction() throws Exception {
		String grammar =
			"grammar t;\n" +
			"s : A ;\n" +
			"A : (B)=>(B|'y'+) {System.out.println(\"alt1\");}\n" +
			"  | B {System.out.println(\"alt2\");}\n" +
			"  | 'y'+ ';'" +
			"  ;\n" +
			"fragment\n" +
			"B : 'x'+ ;\n" ;
		String found = execParser("t.g", grammar, "tParser", "tLexer",
				    "s", "xxx", false);

		assertEquals("alt1\n", found);
	}

	public void testLexerPredCyclicPrediction2() throws Exception {
		String grammar =
			"grammar t;\n" +
			"s : A ;\n" +
			"A : (B '.')=>(B|'y'+) {System.out.println(\"alt1\");}\n" +
			"  | B {System.out.println(\"alt2\");}\n" +
			"  | 'y'+ ';'" +
			"  ;\n" +
			"fragment\n" +
			"B : 'x'+ ;\n" ;
		String found = execParser("t.g", grammar, "tParser", "tLexer",
				    "s", "xxx", false);
		assertEquals("alt2\n", found);
	}

	public void testSimpleNestedPred() throws Exception {
		String grammar =
			"grammar t;\n" +
			"s : (expr ';')+ ;\n" +
			"expr\n" +
			"options {\n" +
			"  k=1;\n" +
			"}\n" +
			"@init {System.out.println(\"enter expr \"+input.LT(1).getText());}\n" +
			"  : (atom 'x') => atom 'x'\n" +
			"  | atom\n" +
			";\n" +
			"atom\n" +
			"@init {System.out.println(\"enter atom \"+input.LT(1).getText());}\n" +
			"   : '(' expr ')'\n" +
			"   | INT\n" +
			"   ;\n" +
			"INT: '0'..'9'+ ;\n" +
			"WS : (' '|'\\n')+ {channel=99;}\n" +
			"   ;\n" ;
		String found = execParser("t.g", grammar, "tParser", "tLexer",
				    "s", "(34)x;", false);
		String expecting =
			"enter expr (\n" +
			"enter atom (\n" +
			"enter expr 34\n" +
			"enter atom 34\n" +
			"enter atom 34\n" +
			"enter atom (\n" +
			"enter expr 34\n" +
			"enter atom 34\n" +
			"enter atom 34\n";
		assertEquals(expecting, found);
	}

	public void testTripleNestedPredInLexer() throws Exception {
		String grammar =
			"grammar t;\n" +
			"s : (.)+ {System.out.println(\"done\");} ;\n" +
			"EXPR\n" +
			"options {\n" +
			"  k=1;\n" +
			"}\n" +
			"@init {System.out.println(\"enter expr \"+(char)input.LT(1));}\n" +
			"  : (ATOM 'x') => ATOM 'x' {System.out.println(\"ATOM x\");}\n" +
			"  | ATOM {System.out.println(\"ATOM \"+$ATOM.text);}\n" +
			";\n" +
			"fragment ATOM\n" +
			"@init {System.out.println(\"enter atom \"+(char)input.LT(1));}\n" +
			"   : '(' EXPR ')'\n" +
			"   | INT\n" +
			"   ;\n" +
			"fragment INT: '0'..'9'+ ;\n" +
			"fragment WS : (' '|'\\n')+ \n" +
			"   ;\n" ;
		String found = execParser("t.g", grammar, "tParser", "tLexer",
				    "s", "((34)x)x", false);
		String expecting = // has no memoization
			"enter expr (\n" +
			"enter atom (\n" +
			"enter expr (\n" +
			"enter atom (\n" +
			"enter expr 3\n" +
			"enter atom 3\n" +
			"enter atom 3\n" +
			"enter atom (\n" +
			"enter expr 3\n" +
			"enter atom 3\n" +
			"enter atom 3\n" +
			"enter atom (\n" +
			"enter expr (\n" +
			"enter atom (\n" +
			"enter expr 3\n" +
			"enter atom 3\n" +
			"enter atom 3\n" +
			"enter atom (\n" +
			"enter expr 3\n" +
			"enter atom 3\n" +
			"enter atom 3\n" +
			"ATOM 34\n" +
			"ATOM x\n" +
			"ATOM x\n" +
			"done\n";
		assertEquals(expecting, found);
	}

	public void testSynPredWithOutputTemplate() throws Exception {
		// really just seeing if it will compile
		String grammar =
			"grammar t;\n" +
			"options {output=template;}\n" +
			"a\n" +
			"options {\n" +
			"  k=1;\n" +
			"}\n" +
			"  : ('x'+ 'y')=> 'x'+ 'y' -> template(a={$text}) <<1:<a>;>>\n" +
			"  | 'x'+ 'z' -> template(a={$text}) <<2:<a>;>>\n"+
			"  ;\n" +
			"WS : (' '|'\\n')+ {channel=99;}\n" +
			"   ;\n" ;
		String found = execParser("t.g", grammar, "tParser", "tLexer",
				    "a", "xxxy", false);

		assertEquals("1:xxxy;\n", found);
	}

	public void testSynPredWithOutputAST() throws Exception {
		// really just seeing if it will compile
		String grammar =
			"grammar t;\n" +
			"options {output=AST;}\n" +
			"a\n" +
			"options {\n" +
			"  k=1;\n" +
			"}\n" +
			"  : ('x'+ 'y')=> 'x'+ 'y'\n" +
			"  | 'x'+ 'z'\n"+
			"  ;\n" +
			"WS : (' '|'\\n')+ {channel=99;}\n" +
			"   ;\n" ;
		String found = execParser("t.g", grammar, "tParser", "tLexer",
				    "a", "xxxy", false);

		assertEquals("x x x y\n", found);
	}

}