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generalize grammar analysis to k>1

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This commit is contained in:
Sven M. Hallberg 2013-05-22 20:38:36 +02:00
parent 337cbc2695
commit f5d5c36756
6 changed files with 468 additions and 136 deletions
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60
src/cfgrammar.h
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@ -8,20 +8,44 @@ typedef struct HCFGrammar_ {
HHashSet *nts; // HCFChoices, each representing the alternative
// productions for one nonterminal
HHashSet *geneps; // set of NTs that can generate the empty string
HHashTable *first; // memoized first sets of the grammar's symbols
HHashTable *follow; // memoized follow sets of the grammar's NTs
HHashTable **first; // memoized first sets of the grammar's symbols
HHashTable **follow; // memoized follow sets of the grammar's NTs
size_t kmax; // maximum lookahead depth allocated
HArena *arena;
HAllocator *mm__;
// constant set containing only the empty string.
// this is only a member of HCFGrammar because it needs a pointer to arena.
const struct HCFStringMap_ *singleton_epsilon;
} HCFGrammar;
/* mapping input bytes or end to tokens
* we want to use these, cast to void *, as elements in hashsets
* therefore we must avoid 0 as a token value because NULL means "not in set".
/* Representing input characters (bytes) in HHashTables.
* To use these as keys, we must avoid 0 as because NULL means "not set".
*/
typedef uintptr_t HCFToken;
static inline HCFToken char_token(uint8_t c) { return (0x100 | c); }
static inline uint8_t token_char(HCFToken t) { return (0xFF & t); }
static const HCFToken end_token = 0x200;
typedef uintptr_t HCharKey;
static inline HCharKey char_key(uint8_t c) { return (0x100 | c); }
static inline uint8_t key_char(HCharKey k) { return (0xFF & k); }
/* Mapping strings of input tokens to arbitrary values (or serving as a set).
* Common prefixes are folded into a tree of HHashTables, branches labeled with
* input tokens.
* Each path through the tree represents the string along its branches.
*/
typedef struct HCFStringMap_ {
void *epsilon_branch; // points to leaf value
void *end_branch; // points to leaf value
HHashTable *char_branches; // maps to inner nodes (HCFStringMaps)
HArena *arena;
} HCFStringMap;
HCFStringMap *h_stringmap_new(HArena *a);
void h_stringmap_put_end(HCFStringMap *m, void *v);
void h_stringmap_put_epsilon(HCFStringMap *m, void *v);
void h_stringmap_put_char(HCFStringMap *m, uint8_t c, void *v);
void h_stringmap_update(HCFStringMap *m, const HCFStringMap *n);
void *h_stringmap_get(const HCFStringMap *m, const uint8_t *str, size_t n, bool end);
bool h_stringmap_present(const HCFStringMap *m, const uint8_t *str, size_t n, bool end);
/* Convert 'parser' into CFG representation by desugaring and compiling the set
@ -36,22 +60,22 @@ HCFGrammar *h_cfgrammar(HAllocator* mm__, const HParser *parser);
void h_cfgrammar_free(HCFGrammar *g);
/* Does the given symbol derive the empty string (under g)? */
bool h_symbol_derives_epsilon(HCFGrammar *g, const HCFChoice *symbol);
bool h_derives_epsilon(HCFGrammar *g, const HCFChoice *symbol);
/* Does the sentential form s derive the empty string? s NULL-terminated. */
bool h_sequence_derives_epsilon(HCFGrammar *g, HCFChoice **s);
bool h_derives_epsilon_seq(HCFGrammar *g, HCFChoice **s);
/* Compute first set of sentential form s. s NULL-terminated. */
HHashSet *h_first_sequence(HCFGrammar *g, HCFChoice **s);
/* Compute first_k set of symbol x. Memoized. */
const HCFStringMap *h_first(size_t k, HCFGrammar *g, const HCFChoice *x);
/* Compute first set of symbol x. Memoized. */
HHashSet *h_first_symbol(HCFGrammar *g, const HCFChoice *x);
/* Compute first_k set of sentential form s. s NULL-terminated. */
const HCFStringMap *h_first_seq(size_t k, HCFGrammar *g, HCFChoice **s);
/* Compute follow set of symbol x. Memoized. */
HHashSet *h_follow(HCFGrammar *g, const HCFChoice *x);
/* Compute follow_k set of symbol x. Memoized. */
const HCFStringMap *h_follow(size_t k, HCFGrammar *g, const HCFChoice *x);
/* Pretty-printers for grammars and associated data. */
void h_pprint_grammar(FILE *file, const HCFGrammar *g, int indent);
void h_pprint_symbolset(FILE *file, const HCFGrammar *g, const HHashSet *set, int indent);
void h_pprint_tokenset(FILE *file, const HCFGrammar *g, const HHashSet *set, int indent);
void h_pprint_stringset(FILE *file, const HCFGrammar *g, const HCFStringMap *set, int indent);