forgetest1
/
antlr
forked from jasder/antlr
1
0
Fork 0
Code Issues Pull Requests 1 Releases Wiki Activity

add {} in primary alt block to prevent ID|INT from becoming SET, which breaks code gen needs.

This commit is contained in:
Terence Parr 2012-03-27 16:21:01 -07:00
parent bd51907c5e
commit 9c1e58db7c
3 changed files with 59 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
tool/playground/T.g
View File

@ -1,6 +1,8 @@
grammar T;
s : f f EOF;
f : | x;
x : 'a' 'b';
s : e ';' ;
e : e '*' e
| ID
| INT
;
INT : '0'..'9'+;
WS : (' '|'\n') {skip();} ;

2
tool/resources/org/antlr/v4/tool/templates/LeftRecursiveRules.stg
View File

@ -37,7 +37,7 @@ recRule(ruleName, precArgDef, argName, primaryAlts, opAlts, setResultAction,
userRetvals, leftRecursiveRuleRefLabels) ::=
<<
<ruleName>[<precArgDef>]<if(userRetvals)> returns [<userRetvals>]<endif>
: ( <primaryAlts:{alt | <alt.altText> }; separator="\n | ">
: ( {} <primaryAlts:{alt | <alt.altText> }; separator="\n | ">
)
( <opAlts; separator="\n | ">
)*

53
tool/test/org/antlr/v4/test/TestLeftRecursion.java
View File

@ -276,6 +276,59 @@ public class TestLeftRecursion extends BaseTest {
runTests(grammar, tests, "s");
}
@Test
public void testAmbigLR() throws Exception {
String grammar =
"// START: g\n" +
"grammar Expr;\n" +
"// END: g\n" +
"\n" +
"// START:stat\n" +
"prog: stat ;\n" +
"\n" +
"stat: expr NEWLINE -> printExpr\n" +
" | ID '=' expr NEWLINE -> assign\n" +
" | NEWLINE -> blank\n" +
" ;\n" +
"// END:stat\n" +
"\n" +
"// START:expr\n" +
"expr: expr ('*'|'/') expr -> MulDiv\n" +
" | expr ('+'|'-') expr -> AddSub\n" +
" | INT -> int\n" +
" | ID -> id\n" +
" | '(' expr ')' -> parens\n" +
" ;\n" +
"// END:expr\n" +
"\n" +
"// show marginal cost of adding a clear/wipe command for memory\n" +
"\n" +
"// START:tokens\n" +
"MUL : '*' ; // assigns token name to '*' used above in grammar\n" +
"DIV : '/' ;\n" +
"ADD : '+' ;\n" +
"SUB : '-' ;\n" +
"ID : [a-zA-Z]+ ; // match identifiers\n" +
"INT : [0-9]+ ; // match integers\n" +
"NEWLINE:'\\r'? '\\n' ; // return newlines to parser (is end-statement signal)\n" +
"WS : [ \\t]+ -> skip ; // toss out whitespace\n" +
"// END:tokens\n";
String result = execParser("Expr.g4", grammar, "ExprParser", "ExprLexer", "prog", "1\n", true);
assertNull(stderrDuringParse);
result = execParser("Expr.g4", grammar, "ExprParser", "ExprLexer", "prog", "a = 5\n", true);
assertNull(stderrDuringParse);
result = execParser("Expr.g4", grammar, "ExprParser", "ExprLexer", "prog", "b = 6\n", true);
assertNull(stderrDuringParse);
result = execParser("Expr.g4", grammar, "ExprParser", "ExprLexer", "prog", "a+b*2\n", true);
assertNull(stderrDuringParse);
result = execParser("Expr.g4", grammar, "ExprParser", "ExprLexer", "prog", "(1+2)*3\n", true);
assertNull(stderrDuringParse);
}
public void runTests(String grammar, String[] tests, String startRule) {
rawGenerateAndBuildRecognizer("T.g", grammar, "TParser", "TLexer");
writeRecognizerAndCompile("TParser",