GerHobbelt
commented
7 years ago @$ is the yylloc info result of the rule, similar to $$ being the value result.
Previously (0.4.18-xxx) you got away with this in most circumstances because 0.4.18 run-time always performed the old 'default actions':
$$ = $1;
@$ = @1;before executing any rule action code chunk, so that $$ and @$ acted as identical copies of $1 and @1. v0.6.0-XXX doesn't do this any more (for run-time performance reasons) and only injects default actions when there's no user code at all (which is more like the bison behaviour, incidentally).
Anyway, long story short:
The correct way to reference any rule production term, is by numeric or named reference, e.g.
character: 'CHARACTER' { console.log(@1); }
;but I never use the quoted token names as that is only extra overhead cost, hence your example would be written as (showcasing 'named reference' for CHARACTER, by the way):
%lex
%%
. return 'CHARACTER';
/lex
%start characters
// %token CHARACTER <-- is *implicit* due to the way I wrote the character rule below
%%
characters
: character
| characters character
;
character: CHARACTER
{ console.log(@CHARACTER); }
;The next snippet is a self-contained executable, if you compile it with jison --main (see jison --help):
%lex
%%
. return 'CHARACTER';
/lex
%start characters
// %token CHARACTER <-- is *implicit* due to the way I wrote the character rule below
%%
characters
: character
| characters character
;
character: CHARACTER
{ console.log(@CHARACTER); } // or use `@1` to ref the 1st term in the rule production
;
%%
// compile with `jison --main test.jison`
// then execute this `main()` with `node test.js`
parser.main = function () {
parser.parse('abc');
};
nwhetsell
I’m not sure if I’m doing something wrong, but result locations
@$seem to be alwaysundefinedin v0.6.0-188. If I runon macOS 10.12.6, the output is