upb/hash/str_table.h

// Protocol Buffers - Google's data interchange format
// Copyright 2023 Google LLC.  All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd

#ifndef UPB_HASH_STR_TABLE_H_
#define UPB_HASH_STR_TABLE_H_

#include "upb/hash/common.h"

// Must be last.
#include "upb/port/def.inc"

typedef struct {
  upb_table t;
} upb_strtable;

#ifdef __cplusplus
extern "C" {
#endif

// Initialize a table. If memory allocation failed, false is returned and
// the table is uninitialized.
bool upb_strtable_init(upb_strtable* table, size_t expected_size, upb_Arena* a);

// Returns the number of values in the table.
UPB_INLINE size_t upb_strtable_count(const upb_strtable* t) {
  return t->t.count;
}

void upb_strtable_clear(upb_strtable* t);

// Inserts the given key into the hashtable with the given value.
// The key must not already exist in the hash table. The key is not required
// to be NULL-terminated, and the table will make an internal copy of the key.
//
// If a table resize was required but memory allocation failed, false is
// returned and the table is unchanged. */
bool upb_strtable_insert(upb_strtable* t, const char* key, size_t len,
                         upb_value val, upb_Arena* a);

// Looks up key in this table, returning "true" if the key was found.
// If v is non-NULL, copies the value for this key into *v.
bool upb_strtable_lookup2(const upb_strtable* t, const char* key, size_t len,
                          upb_value* v);

// For NULL-terminated strings.
UPB_INLINE bool upb_strtable_lookup(const upb_strtable* t, const char* key,
                                    upb_value* v) {
  return upb_strtable_lookup2(t, key, strlen(key), v);
}

// Removes an item from the table. Returns true if the remove was successful,
// and stores the removed item in *val if non-NULL.
bool upb_strtable_remove2(upb_strtable* t, const char* key, size_t len,
                          upb_value* val);

UPB_INLINE bool upb_strtable_remove(upb_strtable* t, const char* key,
                                    upb_value* v) {
  return upb_strtable_remove2(t, key, strlen(key), v);
}

// Exposed for testing only.
bool upb_strtable_resize(upb_strtable* t, size_t size_lg2, upb_Arena* a);

/* Iteration over strtable:
 *
 *   intptr_t iter = UPB_STRTABLE_BEGIN;
 *   upb_StringView key;
 *   upb_value val;
 *   while (upb_strtable_next2(t, &key, &val, &iter)) {
 *      // ...
 *   }
 */

#define UPB_STRTABLE_BEGIN -1

bool upb_strtable_next2(const upb_strtable* t, upb_StringView* key,
                        upb_value* val, intptr_t* iter);
void upb_strtable_removeiter(upb_strtable* t, intptr_t* iter);
void upb_strtable_setentryvalue(upb_strtable* t, intptr_t iter, upb_value v);

/* DEPRECATED iterators, slated for removal.
 *
 * Iterators for string tables.  We are subject to some kind of unusual
 * design constraints:
 *
 * For high-level languages:
 *  - we must be able to guarantee that we don't crash or corrupt memory even if
 *    the program accesses an invalidated iterator.
 *
 * For C++11 range-based for:
 *  - iterators must be copyable
 *  - iterators must be comparable
 *  - it must be possible to construct an "end" value.
 *
 * Iteration order is undefined.
 *
 * Modifying the table invalidates iterators.  upb_{str,int}table_done() is
 * guaranteed to work even on an invalidated iterator, as long as the table it
 * is iterating over has not been freed.  Calling next() or accessing data from
 * an invalidated iterator yields unspecified elements from the table, but it is
 * guaranteed not to crash and to return real table elements (except when done()
 * is true). */
/* upb_strtable_iter **********************************************************/

/*   upb_strtable_iter i;
 *   upb_strtable_begin(&i, t);
 *   for(; !upb_strtable_done(&i); upb_strtable_next(&i)) {
 *     const char *key = upb_strtable_iter_key(&i);
 *     const upb_value val = upb_strtable_iter_value(&i);
 *     // ...
 *   }
 */

typedef struct {
  const upb_strtable* t;
  size_t index;
} upb_strtable_iter;

UPB_INLINE const upb_tabent* str_tabent(const upb_strtable_iter* i) {
  return &i->t->t.entries[i->index];
}

void upb_strtable_begin(upb_strtable_iter* i, const upb_strtable* t);
void upb_strtable_next(upb_strtable_iter* i);
bool upb_strtable_done(const upb_strtable_iter* i);
upb_StringView upb_strtable_iter_key(const upb_strtable_iter* i);
upb_value upb_strtable_iter_value(const upb_strtable_iter* i);
void upb_strtable_iter_setdone(upb_strtable_iter* i);
bool upb_strtable_iter_isequal(const upb_strtable_iter* i1,
                               const upb_strtable_iter* i2);

#ifdef __cplusplus
} /* extern "C" */
#endif

#include "upb/port/undef.inc"

#endif /* UPB_HASH_STR_TABLE_H_ */