add stub GLR backend with h_glr_parse() a copy of h_lr_parse()

src/backends/glr.c

@@ -0,0 +1,93 @@
+#include "lr.h"
+
+
+
+/* GLR driver */
+
+HParseResult *h_glr_parse(HAllocator* mm__, const HParser* parser, HInputStream* stream)
+{
+  HLRTable *table = parser->backend_data;
+  if(!table)
+    return NULL;
+
+  HArena *arena  = h_new_arena(mm__, 0);    // will hold the results
+  HArena *tarena = h_new_arena(mm__, 0);    // tmp, deleted after parse
+  HLREngine *engine = h_lrengine_new(arena, tarena, table);
+
+  // iterate engine to completion
+  while(h_lrengine_step(engine, h_lrengine_action(engine, stream)));
+
+  HParseResult *result = h_lrengine_result(engine);
+  if(!result)
+    h_delete_arena(arena);
+  h_delete_arena(tarena);
+  return result;
+}
+
+
+
+HParserBackendVTable h__glr_backend_vtable = {
+  .compile = h_lalr_compile,
+  .parse = h_glr_parse,
+  .free = h_lalr_free
+};
+
+
+
+
+// dummy!
+int test_glr(void)
+{
+  /* 
+     E -> E '-' T
+        | T
+     T -> '(' E ')'
+        | 'n'               -- also try [0-9] for the charset paths
+  */
+
+  HParser *n = h_ch('n');
+  HParser *E = h_indirect();
+  HParser *T = h_choice(h_sequence(h_ch('('), E, h_ch(')'), NULL), n, NULL);
+  HParser *E_ = h_choice(h_sequence(E, h_ch('-'), T, NULL), T, NULL);
+  h_bind_indirect(E, E_);
+  HParser *p = E;
+
+  printf("\n==== G R A M M A R ====\n");
+  HCFGrammar *g = h_cfgrammar(&system_allocator, p);
+  if(g == NULL) {
+    fprintf(stderr, "h_cfgrammar failed\n");
+    return 1;
+  }
+  h_pprint_grammar(stdout, g, 0);
+
+  printf("\n==== D F A ====\n");
+  HLRDFA *dfa = h_lr0_dfa(g);
+  if(dfa)
+    h_pprint_lrdfa(stdout, g, dfa, 0);
+  else
+    fprintf(stderr, "h_lalr_dfa failed\n");
+
+  printf("\n==== L R ( 0 )  T A B L E ====\n");
+  HLRTable *table0 = h_lr0_table(g, dfa);
+  if(table0)
+    h_pprint_lrtable(stdout, g, table0, 0);
+  else
+    fprintf(stderr, "h_lr0_table failed\n");
+  h_lrtable_free(table0);
+
+  printf("\n==== L A L R  T A B L E ====\n");
+  if(h_compile(p, PB_GLR, NULL)) {
+    fprintf(stderr, "does not compile\n");
+    return 2;
+  }
+  h_pprint_lrtable(stdout, g, (HLRTable *)p->backend_data, 0);
+
+  printf("\n==== P A R S E  R E S U L T ====\n");
+  HParseResult *res = h_parse(p, (uint8_t *)"n-(n-((n)))-n", 13);
+  if(res)
+    h_pprint(stdout, res->ast, 0, 2);
+  else
+    printf("no parse\n");
+
+  return 0;
+}

src/backends/lr.h

@@ -131,6 +131,7 @@ const HLRAction *h_lrengine_action(HLREngine *engine, HInputStream *stream);
 bool h_lrengine_step(HLREngine *engine, const HLRAction *action);
 HParseResult *h_lrengine_result(HLREngine *engine);
 HParseResult *h_lr_parse(HAllocator* mm__, const HParser* parser, HInputStream* stream);
+HParseResult *h_glr_parse(HAllocator* mm__, const HParser* parser, HInputStream* stream);
 
 void h_pprint_lritem(FILE *f, const HCFGrammar *g, const HLRItem *item);
 void h_pprint_lrstate(FILE *f, const HCFGrammar *g,