diff --git a/src/backends/lalr.c b/src/backends/lalr.c
index 7a1c04ac2b7334683d0fb9a2453eb6f4554407c4..79e03c75a4bf9e16b4daae83e6dac93a2469344b 100644
--- a/src/backends/lalr.c
+++ b/src/backends/lalr.c
@@ -61,6 +61,16 @@ typedef struct HLREnhGrammar_ {
HArena *arena;
} HLREnhGrammar;
+typedef struct HLREngine_ {
+ const HLRTable *table;
+ HSlist *left; // left stack; reductions happen here
+ HSlist *right; // right stack; input appears here
+ size_t state;
+ bool running;
+ HArena *arena; // will hold the results
+ HArena *tarena; // tmp, deleted after parse
+} HLREngine;
+
// XXX move to internal.h or something
// XXX replace other hashtable iterations with this
@@ -733,118 +743,149 @@ h_lr_lookup(const HLRTable *table, size_t state, const HCFChoice *symbol)
}
}
-HParseResult *h_lr_parse(HAllocator* mm__, const HParser* parser, HInputStream* stream)
+HLREngine *h_lrengine_new(HArena *arena, HArena *tarena, const HLRTable *table)
{
- HLRTable *table = parser->backend_data;
- if(!table)
- return NULL;
+ HLREngine *engine = h_arena_malloc(tarena, sizeof(HLREngine));
- HArena *arena = h_new_arena(mm__, 0); // will hold the results
- HArena *tarena = h_new_arena(mm__, 0); // tmp, deleted after parse
- HSlist *left = h_slist_new(tarena); // left stack; reductions happen here
- HSlist *right = h_slist_new(tarena); // right stack; input appears here
+ engine->table = table;
+ engine->left = h_slist_new(tarena);
+ engine->right = h_slist_new(tarena);
+ engine->state = 0;
+ engine->running = 1;
+ engine->arena = arena;
+ engine->tarena = tarena;
+
+ return engine;
+}
+
+void h_lrengine_step(HLREngine *engine, HInputStream *stream)
+{
+ // short-hand names
+ HSlist *left = engine->left;
+ HSlist *right = engine->right;
+ HArena *arena = engine->arena;
+ HArena *tarena = engine->tarena;
// stack layout:
// on the left stack, we put pairs: (saved state, semantic value)
// on the right stack, we put pairs: (symbol, semantic value)
- // run while the recognizer finds handles in the input
- size_t state = 0;
- while(1) {
- // make sure there is input on the right stack
- if(h_slist_empty(right)) {
- // XXX use statically-allocated terminal symbols
- HCFChoice *x = h_arena_malloc(tarena, sizeof(HCFChoice));
- HParsedToken *v;
-
- uint8_t c = h_read_bits(stream, 8, false);
-
- if(stream->overrun) { // end of input
- x->type = HCF_END;
- v = NULL;
- } else {
- x->type = HCF_CHAR;
- x->chr = c;
- v = h_arena_malloc(arena, sizeof(HParsedToken));
- v->token_type = TT_UINT;
- v->uint = c;
- }
+ // make sure there is input on the right stack
+ if(h_slist_empty(right)) {
+ // XXX use statically-allocated terminal symbols
+ HCFChoice *x = h_arena_malloc(tarena, sizeof(HCFChoice));
+ HParsedToken *v;
+
+ uint8_t c = h_read_bits(stream, 8, false);
- h_slist_push(right, v);
- h_slist_push(right, x);
+ if(stream->overrun) { // end of input
+ x->type = HCF_END;
+ v = NULL;
+ } else {
+ x->type = HCF_CHAR;
+ x->chr = c;
+ v = h_arena_malloc(arena, sizeof(HParsedToken));
+ v->token_type = TT_UINT;
+ v->uint = c;
}
- // peek at input symbol on the right side
- HCFChoice *symbol = right->head->elem;
+ h_slist_push(right, v);
+ h_slist_push(right, x);
+ }
- // table lookup
- const HLRAction *action = h_lr_lookup(table, state, symbol);
- if(action == NULL)
- break; // no handle recognizable in input, terminate parsing
+ // peek at input symbol on the right side
+ HCFChoice *symbol = right->head->elem;
- if(action->type == HLR_SHIFT) {
- h_slist_push(left, (void *)(uintptr_t)state);
- h_slist_pop(right); // symbol (discard)
- h_slist_push(left, h_slist_pop(right)); // semantic value
- state = action->nextstate;
- } else {
- assert(action->type == HLR_REDUCE);
- size_t len = action->production.length;
- HCFChoice *symbol = action->production.lhs;
-
- // semantic value of the reduction result
- HParsedToken *value = h_arena_malloc(arena, sizeof(HParsedToken));
- value->token_type = TT_SEQUENCE;
- value->seq = h_carray_new_sized(arena, len);
-
- // pull values off the left stack, rewinding state accordingly
- HParsedToken *v = NULL;
- for(size_t i=0; i<len; i++) {
- v = h_slist_pop(left);
- state = (uintptr_t)h_slist_pop(left);
-
- // collect values in result sequence
- value->seq->elements[len-1-i] = v;
- value->seq->used++;
- }
- if(v) {
- // result position equals position of left-most symbol
- value->index = v->index;
- value->bit_offset = v->bit_offset;
- } else {
- // XXX how to get the position in this case?
- }
+ // table lookup
+ const HLRAction *action = h_lr_lookup(engine->table, engine->state, symbol);
+ if(action == NULL) {
+ // no handle recognizable in input, terminate
+ engine->running = false;
+ return;
+ }
- // perform token reshape if indicated
- if(symbol->reshape)
- value = (HParsedToken *)symbol->reshape(make_result(arena, value));
+ if(action->type == HLR_SHIFT) {
+ h_slist_push(left, (void *)(uintptr_t)engine->state);
+ h_slist_pop(right); // symbol (discard)
+ h_slist_push(left, h_slist_pop(right)); // semantic value
+ engine->state = action->nextstate;
+ } else {
+ assert(action->type == HLR_REDUCE);
+ size_t len = action->production.length;
+ HCFChoice *symbol = action->production.lhs;
+
+ // semantic value of the reduction result
+ HParsedToken *value = h_arena_malloc(arena, sizeof(HParsedToken));
+ value->token_type = TT_SEQUENCE;
+ value->seq = h_carray_new_sized(arena, len);
+
+ // pull values off the left stack, rewinding state accordingly
+ HParsedToken *v = NULL;
+ for(size_t i=0; i<len; i++) {
+ v = h_slist_pop(left);
+ engine->state = (uintptr_t)h_slist_pop(left);
+
+ // collect values in result sequence
+ value->seq->elements[len-1-i] = v;
+ value->seq->used++;
+ }
+ if(v) {
+ // result position equals position of left-most symbol
+ value->index = v->index;
+ value->bit_offset = v->bit_offset;
+ } else {
+ // XXX how to get the position in this case?
+ }
- // call validation and semantic action, if present
- if(symbol->pred && !symbol->pred(make_result(tarena, value)))
- break; // validation failed -> no parse
- if(symbol->action)
- value = (HParsedToken *)symbol->action(make_result(arena, value));
+ // perform token reshape if indicated
+ if(symbol->reshape)
+ value = (HParsedToken *)symbol->reshape(make_result(arena, value));
- // push result (value, symbol) onto the right stack
- h_slist_push(right, value);
- h_slist_push(right, symbol);
+ // call validation and semantic action, if present
+ if(symbol->pred && !symbol->pred(make_result(tarena, value))) {
+ // validation failed -> no parse; terminate
+ engine->running = false;
+ return;
}
- }
-
+ if(symbol->action)
+ value = (HParsedToken *)symbol->action(make_result(arena, value));
+ // push result (value, symbol) onto the right stack
+ h_slist_push(right, value);
+ h_slist_push(right, symbol);
+ }
+}
+HParseResult *h_lrengine_result(HLREngine *engine)
+{
// parsing was successful iff the start symbol is on top of the right stack
- HParseResult *result = NULL;
- if(h_slist_pop(right) == table->start) {
+ if(h_slist_pop(engine->right) == engine->table->start) {
// next on the right stack is the start symbol's semantic value
- assert(!h_slist_empty(right));
- HParsedToken *tok = h_slist_pop(right);
- result = make_result(arena, tok);
+ assert(!h_slist_empty(engine->right));
+ HParsedToken *tok = h_slist_pop(engine->right);
+ return make_result(engine->arena, tok);
} else {
- h_delete_arena(arena);
- result = NULL;
+ return NULL;
}
+}
+HParseResult *h_lr_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);
+
+ // run while the recognizer finds handles in the input
+ while(engine->running)
+ h_lrengine_step(engine, stream);
+
+ HParseResult *result = h_lrengine_result(engine);
+ if(!result)
+ h_delete_arena(arena);
h_delete_arena(tarena);
return result;
}