url/colibri
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

SCHEMA=<file.json>: JSON-Schema -> GBNF compiler for grammar-forced drafts (#148)

Browse Source 
* SCHEMA=<file.json>: JSON-Schema -> GBNF compiler for grammar-forced drafts (#48/#70 follow-up)

schema_gbnf.h compiles a practical JSON-Schema subset (strict objects, string/
number/integer/boolean/null, enum/const, arrays with items, nesting) into the
byte-level GBNF subset grammar.h parses, so structured-output workloads get
grammar-forced drafts without hand-writing GBNF. Unsupported keywords fail soft:
the engine runs without a grammar and output is unchanged (drafts are verified,
never constraints - a wrong compile can only cost acceptance, not correctness).

grammar_setup: GRAMMAR= (raw GBNF) keeps precedence; SCHEMA= feeds the compiler
into the same gr_parse path. 8 test groups in tests/test_schema_gbnf.c walk
compiled grammars end-to-end through the PDA (forced spans, enum disambiguation,
nested instances, escapes, leading-zero rejection, fail-closed fallbacks).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* schema_gbnf: whitespace-tolerant emission (jws at separators)

Measured on GLM-5.2 current main (#146): the greedy continuation writes sloppy
JSON (spaces after colons, fences, long free text) and a compact-only grammar
desyncs at the first stray space, forfeiting every span after it. jws points are
not forced themselves (two legal bytes) but the multi-byte spans around them
keep drafting and the walker survives non-compact output - strictly
acceptance-positive for a verified draft source. Tests re-derived for the new
span boundaries + a sloppy-instance walk.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: JustVugg <JustVugg@users.noreply.github.com>
This commit is contained in:
Fabio Rovai
2026-07-14 15:31:09 +01:00
committed by GitHub
parent 9b08cbc543
commit 504fcdd930
4 changed files with 426 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files
c/glm.c
+21 -7
View File
@@ -39,6 +39,7 @@
#include "tok.h"
#include "tier.h"
#include "grammar.h" /* metodo F: draft grammaticali (#48) */
#include "schema_gbnf.h" /* SCHEMA=: JSON-Schema -> GBNF for method F */
#include "decode_batch.h"
#ifdef _OPENMP
#include <omp.h> /* scratch per-thread nell'attention */
@@ -2660,23 +2661,36 @@ static inline int argmax_v(const float *lo, int V){
* gia' tokenizzato. Il confine di tokenizzazione non e' garantito coincidere con quello
* del modello: la verifica assorbe la differenza (al peggio l'ultimo draft e' rifiutato). */
static void grammar_setup(Tok *T){
const char *gf=getenv("GRAMMAR"); if(!gf||!*gf) return;
FILE *f=fopen(gf,"rb");
if(!f){ fprintf(stderr,"[GRAMMAR] cannot open %s\n",gf); return; }
/* GRAMMAR=<file.gbnf> takes precedence; SCHEMA=<file.json> compiles a JSON-Schema
* to GBNF (schema_gbnf.h) for the same draft source. Both fail soft: the engine
* runs without a grammar and output is unchanged. */
const char *gf=getenv("GRAMMAR");
const char *sf=(gf&&*gf)?NULL:getenv("SCHEMA");
if((!gf||!*gf)&&(!sf||!*sf)) return;
const char *path=(gf&&*gf)?gf:sf;
FILE *f=fopen(path,"rb");
if(!f){ fprintf(stderr,"[GRAMMAR] cannot open %s\n",path); return; }
fseek(f,0,SEEK_END); long n=ftell(f); fseek(f,0,SEEK_SET);
char *txt=malloc((size_t)n+1);
if(!txt || fread(txt,1,(size_t)n,f)!=(size_t)n){
fprintf(stderr,"[GRAMMAR] failed to read %s\n",gf); fclose(f); free(txt); return; }
fprintf(stderr,"[GRAMMAR] failed to read %s\n",path); fclose(f); free(txt); return; }
fclose(f); txt[n]=0;
if(gr_parse(&g_gram,txt)){ fprintf(stderr,"[GRAMMAR] %s: %s\n",gf,g_gram.err); free(txt); return; }
if(sf){ /* schema -> GBNF, then the same gr_parse as the GRAMMAR path */
char serr[160];
char *gbnf=schema_to_gbnf(txt,serr,sizeof serr);
free(txt);
if(!gbnf){ fprintf(stderr,"[SCHEMA] %s: %s (running without grammar)\n",sf,serr); return; }
txt=gbnf;
}
if(gr_parse(&g_gram,txt)){ fprintf(stderr,"[GRAMMAR] %s: %s\n",path,g_gram.err); free(txt); return; }
free(txt);
gr_state_init(&g_gst,&g_gram);
if(!g_gst.alive){ fprintf(stderr,"[GRAMMAR] %s: grammar cannot be evaluated (left recursion?)\n",gf); return; }
if(!g_gst.alive){ fprintf(stderr,"[GRAMMAR] %s: grammar cannot be evaluated (left recursion?)\n",path); return; }
if(getenv("GRAMMAR_DRAFT")) g_gr_max=atoi(getenv("GRAMMAR_DRAFT"));
if(g_gr_max<1) g_gr_max=1;
if(g_gr_max>48) g_gr_max=48;
g_gr_T=T; g_gr_on=1;
fprintf(stderr,"[GRAMMAR] %s: %d rules, forced span capped at %d tokens/forward\n",gf,g_gram.n,g_gr_max);
fprintf(stderr,"[GRAMMAR] %s: %d rules, forced span capped at %d tokens/forward\n",path,g_gram.n,g_gr_max);
}
/* stato pulito all'inizio di ogni RISPOSTA (non tra i \x02MORE, che continuano) */
static void grammar_reset(void){