When this grammar is given the following input, a few bugs are observed,
as shown in the output.
Input: "ident ident" (no quotes)
Output:
Setting scope at level 1 to true
4: b is false size = 2 bt = 2
3: b is false size = 2 bt = 2
2: b is false size = 2 bt = 2
4: b is true size = 1 bt = 1
4: b is false size = 2 bt = 1
3: b is false size = 2 bt = 1
2: b is false size = 2 bt = 1
1: b is true size = 1 bt = 1
Exception in thread "main" java.util.EmptyStackException
at java.util.Stack.peek(Unknown Source)
at
TestSemPredScopesParser.test(TestSemPredScopesParser.java:98)
at __Test__.main(__Test__.java:14)
Grammar:
grammar TestSemPredScopes;
scope MyScope { boolean b; }
@parser::members {
boolean report( int n, boolean b ) {
System.err.println( n + ": b is " + b + " size = " +
MyScope_stack.size() + " bt = " + state.backtracking);
return true;
}
}
test
: ( (subrule1) => subrule1
| subrule2
)
EOF
;
subrule1
scope MyScope;
: nest1subrule1
;
nest1subrule1
@init
{
System.err.println( "Setting scope at level " +
MyScope_stack.size() + " to true" );
$MyScope::b = true;
}
: (nest2subrule1) => nest2subrule1
{report(1,$MyScope::b)}?
| subrule2
;
nest2subrule1
scope MyScope;
: nest3subrule1 {report(2,$MyScope::b)}? ;
nest3subrule1
: {report(4,$MyScope::b) /*&& !$MyScope::b*/}? =>
{report(3,$MyScope::b)}? IDENTIFIER IDENTIFIER
;
subrule2 : IDENTIFIER ;
IDENTIFIER : ('a'..'z')+ ;
WS : (' ' | '\t')+ {$channel = HIDDEN;} ;
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