antlr4 grammar-locals clause doesn't generate variable declaration in Parser

Question

Based on this answer I made my rule like:

ompParallel
  locals [java.util.HashSet<String> names = new java.util.HashSet<String>();]
  : SOME_LEXER_CONSTANT modifiers ;

modifiers
//Ensure that the full number of modifiers have been provided
: {$ompParallel::names.size() < 3}? predicateModifier modifiers
| {$ompParallel::names.size() == 3}? //match nothing once we have (any) three modifiers
;

predicateModifier
//Ensure that no duplicates have been provided
: {!$ompParallel::names.contains("a")}? A {$ompParallel::names.add("a");}
| {!$ompParallel::names.contains("b")}? B {$ompParallel::names.add("b");}
| {!$ompParallel::names.contains("c")}? C {$ompParallel::names.add("c");}
;

but in generated Parser there is only

public java.util.HashSet<String> names;

without declaration = new java.util.HashSet<String>();.

According to last snippet of this answer I tried something like

ruleName
  @init {
      java.util.HashSet<String> names = new java.util.HashSet<String>();
  }
  : SOME_LEXER_CONSTANT modifiers ;

This led to grammar-compilation error

 unknown attribute names for rule ompParallel in $ompParallel::names

I am really confused, could someone help me out? Preferably fixin the first alternative (using locals [...].

EDIT1: related source

Try to remove the `;` in your first attempt just before the `]`. If that doesn't work, as a workaround you could try to combine both approaches: declare the variable with `locals [java.util.HashSet names]` and init it with `@init { names = new java.util.HashSet(); }` but... meh. — Lucas Trzesniewski, Nov 14 '14 at 00:56
The former solution didn't help, nevertheless the letter did (with some tweaks, please see my answer below) thanks! Anyway I consider this a problem and I'll try to report it to some issue tracker. — petrbel, Nov 14 '14 at 07:30

score 0 · Accepted Answer · edited May 23 '17 at 12:05

0

thanks to @Lucas I figured it out:

ompParallel    
locals [static java.util.HashSet<String> names]
@init {
    OmpParallelContext.names = new java.util.HashSet<String>();
}
: PARALLEL modifiers ;

One needs to define the variable statically in order to access it from different class. Unfortunately ANTLR4 generated Parser code seems to be little clumsy.

edited May 23 '17 at 12:05

Community

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answered Nov 14 '14 at 07:33

petrbel

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anyway one should be very careful when using `static` in recursive rules – petrbel Nov 14 '14 at 15:28

antlr4 grammar-locals clause doesn't generate variable declaration in Parser

1 Answers1