lr driver, first stab (still bugged)
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Sven M. Hallberg
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bbdced376e
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0a7548bb2f
1 changed files with 207 additions and 75 deletions
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@ -7,11 +7,7 @@
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/* Data structures */
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// - states are hashsets containing LRItems
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// - LRItems contain an optional lookahead set (HStringMap)
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// - states (hashsets) get hash and comparison functions that ignore the lookahead
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typedef HHashSet HLRState;
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typedef HHashSet HLRState; // states are sets of LRItems
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typedef struct HLRDFA_ {
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size_t nstates;
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@ -30,7 +26,6 @@ typedef struct HLRItem_ {
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HCFChoice **rhs; // NULL-terminated
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size_t len; // number of elements in rhs
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size_t mark;
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HStringMap *lookahead; // optional
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} HLRItem;
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typedef struct HLRAction_ {
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@ -56,27 +51,28 @@ typedef struct HLRTable_ {
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} HLRTable;
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/* Constructing the characteristic automaton (handle recognizer) */
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HLRItem *h_lritem_new(HArena *a, HCFChoice *lhs, HCFChoice **rhs, size_t mark)
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// compare symbols - terminals by value, others by pointer
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static bool eq_symbol(const void *p, const void *q)
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{
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HLRItem *ret = h_arena_malloc(a, sizeof(HLRItem));
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size_t len = 0;
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for(HCFChoice **p=rhs; *p; p++) len++;
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assert(mark <= len);
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ret->lhs = lhs;
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ret->rhs = rhs;
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ret->len = len;
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ret->mark = mark;
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ret->lookahead = NULL;
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return ret;
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const HCFChoice *x=p, *y=q;
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return (x==y
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|| (x->type==HCF_END && y->type==HCF_END)
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|| (x->type==HCF_CHAR && y->type==HCF_CHAR && x->chr==y->chr));
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}
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// compare LALR items - ignores lookahead
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// hash symbols - terminals by value, others by pointer
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static HHashValue hash_symbol(const void *p)
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{
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const HCFChoice *x=p;
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if(x->type == HCF_END)
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return 0;
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else if(x->type == HCF_CHAR)
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return x->chr * 33;
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else
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return h_hash_ptr(p);
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}
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// compare LALR items by value
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static bool eq_lalr_item(const void *p, const void *q)
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{
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const HLRItem *a=p, *b=q;
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@ -124,11 +120,80 @@ static HHashValue hash_lalr_itemset(const void *p)
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return hash;
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}
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HLRItem *h_lritem_new(HArena *a, HCFChoice *lhs, HCFChoice **rhs, size_t mark)
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{
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HLRItem *ret = h_arena_malloc(a, sizeof(HLRItem));
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size_t len = 0;
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for(HCFChoice **p=rhs; *p; p++) len++;
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assert(mark <= len);
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ret->lhs = lhs;
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ret->rhs = rhs;
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ret->len = len;
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ret->mark = mark;
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return ret;
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}
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static inline HLRState *h_lrstate_new(HArena *arena)
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{
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return h_hashset_new(arena, eq_lalr_item, hash_lalr_item);
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}
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HLRTable *h_lrtable_new(HAllocator *mm__, size_t nrows)
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{
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HArena *arena = h_new_arena(mm__, 0); // default blocksize
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assert(arena != NULL);
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HLRTable *ret = h_new(HLRTable, 1);
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ret->nrows = nrows;
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ret->rows = h_arena_malloc(arena, nrows * sizeof(HHashTable *));
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ret->forall = h_arena_malloc(arena, nrows * sizeof(HLRAction *));
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ret->inadeq = h_slist_new(arena);
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ret->arena = arena;
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ret->mm__ = mm__;
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for(size_t i=0; i<nrows; i++) {
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ret->rows[i] = h_hashtable_new(arena, eq_symbol, hash_symbol);
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ret->forall[i] = NULL;
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}
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return ret;
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}
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void h_lrtable_free(HLRTable *table)
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{
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HAllocator *mm__ = table->mm__;
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h_delete_arena(table->arena);
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h_free(table);
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}
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// XXX replace other hashtable iterations with this
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// XXX move to internal.h or something
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#define H_FOREACH_(HT) { \
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const HHashTable *ht__ = HT; \
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for(size_t i__=0; i__ < ht__->capacity; i__++) { \
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for(HHashTableEntry *hte__ = &ht__->contents[i__]; \
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hte__; \
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hte__ = hte__->next) { \
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if(hte__->key == NULL) continue;
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#define H_FOREACH_KEY(HT, KEYVAR) H_FOREACH_(HT) \
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const KEYVAR = hte__->key;
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#define H_FOREACH(HT, KEYVAR, VALVAR) H_FOREACH_KEY(HT, KEYVAR) \
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VALVAR = hte__->value;
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#define H_END_FOREACH \
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} \
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} \
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}
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/* Constructing the characteristic automaton (handle recognizer) */
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static HLRItem *advance_mark(HArena *arena, const HLRItem *item)
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{
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assert(item->rhs[item->mark] != NULL);
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@ -224,7 +289,7 @@ HLRDFA *h_lr0_dfa(HCFGrammar *g)
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HLRState *state = h_slist_pop(work);
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// maps edge symbols to neighbor states (item sets) of s
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HHashTable *neighbors = h_hashtable_new(arena, h_eq_ptr, h_hash_ptr);
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HHashTable *neighbors = h_hashtable_new(arena, eq_symbol, hash_symbol);
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// iterate over closure and generate neighboring sets
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const HHashTable *ht = closure(g, state);
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@ -305,55 +370,6 @@ HLRDFA *h_lr0_dfa(HCFGrammar *g)
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/* LR(0) table generation */
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// XXX replace other hashtable iterations with this
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// XXX move to internal.h or something
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#define H_FOREACH_(HT) { \
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const HHashTable *ht__ = HT; \
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for(size_t i__=0; i__ < ht__->capacity; i__++) { \
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for(HHashTableEntry *hte__ = &ht__->contents[i__]; \
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hte__; \
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hte__ = hte__->next) { \
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if(hte__->key == NULL) continue;
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#define H_FOREACH_KEY(HT, KEYVAR) H_FOREACH_(HT) \
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const KEYVAR = hte__->key;
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#define H_FOREACH(HT, KEYVAR, VALVAR) H_FOREACH_KEY(HT, KEYVAR) \
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VALVAR = hte__->value;
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#define H_END_FOREACH \
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} \
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} \
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}
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HLRTable *h_lrtable_new(HAllocator *mm__, size_t nrows)
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{
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HArena *arena = h_new_arena(mm__, 0); // default blocksize
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assert(arena != NULL);
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HLRTable *ret = h_new(HLRTable, 1);
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ret->nrows = nrows;
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ret->rows = h_arena_malloc(arena, nrows * sizeof(HHashTable *));
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ret->forall = h_arena_malloc(arena, nrows * sizeof(HLRAction *));
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ret->inadeq = h_slist_new(arena);
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ret->arena = arena;
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ret->mm__ = mm__;
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for(size_t i=0; i<nrows; i++) {
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ret->rows[i] = h_hashtable_new(arena, h_eq_ptr, h_hash_ptr);
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ret->forall[i] = NULL;
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}
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return ret;
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}
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void h_lrtable_free(HLRTable *table)
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{
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HAllocator *mm__ = table->mm__;
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h_delete_arena(table->arena);
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h_free(table);
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}
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static HLRAction *shift_action(HArena *arena, size_t nextstate)
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{
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HLRAction *action = h_arena_malloc(arena, sizeof(HLRAction));
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@ -579,9 +595,125 @@ void h_lalr_free(HParser *parser)
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/* LR driver */
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const HLRAction *
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h_lr_lookup(const HLRTable *table, size_t state, const HCFChoice *symbol)
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{
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assert(state < table->nrows);
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if(table->forall[state]) {
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assert(h_hashtable_empty(table->rows[state])); // that would be a conflict
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return table->forall[state];
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} else {
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return h_hashtable_get(table->rows[state], symbol);
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}
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}
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// XXX also, what about charsets!?
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HParseResult *h_lr_parse(HAllocator* mm__, const HParser* parser, HInputStream* stream)
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{
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HLRTable *table = parser->backend_data;
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if(!table)
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return NULL;
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HArena *arena = h_new_arena(mm__, 0); // will hold the results
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HArena *tarena = h_new_arena(mm__, 0); // tmp, deleted after parse
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HSlist *left = h_slist_new(tarena); // left stack; reductions happen here
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HSlist *right = h_slist_new(tarena); // right stack; input appears here
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// stack layout:
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// on the left stack, we put pairs: (saved state, semantic value)
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// on the right stack, we put pairs: (symbol, semantic value)
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// run while the recognizer finds handles in the input
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size_t state = 0;
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while(1) {
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// make sure there is input on the right stack
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if(h_slist_empty(right)) {
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HCFChoice *x = h_arena_malloc(tarena, sizeof(HCFChoice));
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HParsedToken *v;
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uint8_t c = h_read_bits(stream, 8, false);
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if(stream->overrun) { // end of input
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x->type = HCF_END;
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v = NULL;
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} else {
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x->type = HCF_CHAR;
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x->chr = c;
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v = h_arena_malloc(arena, sizeof(HParsedToken));
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v->token_type = TT_UINT;
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v->uint = c;
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}
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h_slist_push(right, v);
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h_slist_push(right, x);
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}
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// peek at input symbol on the right side
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HCFChoice *symbol = right->head->elem;
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// table lookup
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const HLRAction *action = h_lr_lookup(table, state, symbol);
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if(action == NULL)
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break; // no handle recognizable in input, terminate parsing
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if(action->type == HLR_SHIFT) {
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h_slist_push(left, (void *)(uintptr_t)state);
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h_slist_pop(right); // symbol (discard)
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h_slist_push(left, h_slist_pop(right)); // semantic value
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state = action->nextstate;
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} else {
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assert(action->type == HLR_REDUCE);
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size_t len = action->production.length;
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HCFChoice *symbol = action->production.lhs;
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// semantic value of the reduction result
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HParsedToken *value = h_arena_malloc(arena, sizeof(HParsedToken));
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value->token_type = TT_SEQUENCE;
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value->seq = h_carray_new_sized(arena, len);
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// pull values off the left stack, rewinding state accordingly
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HParsedToken *v;
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for(size_t i=0; i<len; i++) {
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v = h_slist_pop(left);
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state = (uintptr_t)h_slist_pop(left);
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// collect values in result sequence
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value->seq->elements[len-1-i] = v;
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value->seq->used++;
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}
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// result position equals position of left-most symbol
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value->index = v->index;
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value->bit_offset = v->bit_offset;
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// perform token reshape if indicated
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if(symbol->reshape)
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value = (HParsedToken *)symbol->reshape(make_result(arena, value));
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// call validation and semantic action, if present
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if(symbol->pred && !symbol->pred(make_result(tarena, value)))
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break; // validation failed -> no parse
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if(symbol->action)
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value = (HParsedToken *)symbol->action(make_result(arena, value));
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// push result (value, symbol) onto the right stack
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h_slist_push(right, value);
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h_slist_push(right, symbol);
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}
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}
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h_delete_arena(tarena);
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// parsing was successful iff the start symbol is on top of the right stack
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if(h_slist_pop(right) == table->start) {
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// next on the right stack is the start symbol's semantic value
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HParsedToken *result = h_slist_pop(right);
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assert(result != NULL);
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return make_result(arena, result);
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} else {
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h_delete_arena(arena);
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return NULL;
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}
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}
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