text: // Protocol Buffers - Google's data interchange format
  // Copyright 2008 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  #include <ext/spl/spl_iterators.h>
  #include <Zend/zend_API.h>
  #include <Zend/zend_interfaces.h>
  
  #include "protobuf.h"
  #include "utf8.h"
  
  ZEND_BEGIN_ARG_INFO_EX(arginfo_offsetGet, 0, 0, 1)
    ZEND_ARG_INFO(0, index)
  ZEND_END_ARG_INFO()
  
  ZEND_BEGIN_ARG_INFO_EX(arginfo_offsetSet, 0, 0, 2)
    ZEND_ARG_INFO(0, index)
    ZEND_ARG_INFO(0, newval)
  ZEND_END_ARG_INFO()
  
  ZEND_BEGIN_ARG_INFO(arginfo_void, 0)
  ZEND_END_ARG_INFO()
  
  // Utilities
  
  void* upb_value_memory(upb_value* v) {
    return (void*)(&v->val);
  }
  
  // -----------------------------------------------------------------------------
  // Basic map operations on top of upb's strtable.
  //
  // Note that we roll our own `Map` container here because, as for
  // `RepeatedField`, we want a strongly-typed container. This is so that any user
  // errors due to incorrect map key or value types are raised as close as
  // possible to the error site, rather than at some deferred point (e.g.,
  // serialization).
  //
  // We build our `Map` on top of upb_strtable so that we're able to take
  // advantage of the native_slot storage abstraction, as RepeatedField does.
  // (This is not quite a perfect mapping -- see the key conversions below -- but
  // gives us full support and error-checking for all value types for free.)
  // -----------------------------------------------------------------------------
  
  // Map values are stored using the native_slot abstraction (as with repeated
  // field values), but keys are a bit special. Since we use a strtable, we need
  // to store keys as sequences of bytes such that equality of those bytes maps
  // one-to-one to equality of keys. We store strings directly (i.e., they map to
  // their own bytes) and integers as native integers (using the native_slot
  // abstraction).
  
  // Note that there is another tradeoff here in keeping string keys as native
  // strings rather than PHP strings: traversing the Map requires conversion to
  // PHP string values on every traversal, potentially creating more garbage. We
  // should consider ways to cache a PHP version of the key if this becomes an
  // issue later.
  
  // Forms a key to use with the underlying strtable from a PHP key value. |buf|
  // must point to TABLE_KEY_BUF_LENGTH bytes of temporary space, used to
  // construct a key byte sequence if needed. |out_key| and |out_length| provide
  // the resulting key data/length.
  #define TABLE_KEY_BUF_LENGTH 8  // sizeof(uint64_t)
  static bool table_key(Map* self, zval* key,
                        char* buf,
                        const char** out_key,
                        size_t* out_length TSRMLS_DC) {
    switch (self->key_type) {
      case UPB_TYPE_STRING:
        if (!protobuf_convert_to_string(key)) {
          return false;
        }
        if (!is_structurally_valid_utf8(Z_STRVAL_P(key), Z_STRLEN_P(key))) {
          zend_error(E_USER_ERROR, "Given key is not UTF8 encoded.");
          return false;
        }
        *out_key = Z_STRVAL_P(key);
        *out_length = Z_STRLEN_P(key);
        break;
  
  #define CASE_TYPE(upb_type, type, c_type, php_type)                   \
    case UPB_TYPE_##upb_type: {                                         \
      c_type type##_value;                                              \
      if (!protobuf_convert_to_##type(key, &type##_value)) {            \
        return false;                                                   \
      }                                                                 \
      native_slot_set(self->key_type, NULL, buf, key TSRMLS_CC);        \
      *out_key = buf;                                                   \
      *out_length = native_slot_size(self->key_type);                   \
      break;                                                            \
    }
        CASE_TYPE(BOOL, bool, int8_t, BOOL)
        CASE_TYPE(INT32, int32, int32_t, LONG)
        CASE_TYPE(INT64, int64, int64_t, LONG)
        CASE_TYPE(UINT32, uint32, uint32_t, LONG)
        CASE_TYPE(UINT64, uint64, uint64_t, LONG)
  
  #undef CASE_TYPE
  
      default:
        // Map constructor should not allow a Map with another key type to be
        // constructed.
        assert(false);
        break;
    }
  
    return true;
  }
  
  // -----------------------------------------------------------------------------
  // MapField methods
  // -----------------------------------------------------------------------------
  
  static zend_function_entry map_field_methods[] = {
    PHP_ME(MapField, __construct,  NULL,              ZEND_ACC_PUBLIC)
    PHP_ME(MapField, offsetExists, arginfo_offsetGet, ZEND_ACC_PUBLIC)
    PHP_ME(MapField, offsetGet,    arginfo_offsetGet, ZEND_ACC_PUBLIC)
    PHP_ME(MapField, offsetSet,    arginfo_offsetSet, ZEND_ACC_PUBLIC)
    PHP_ME(MapField, offsetUnset,  arginfo_offsetGet, ZEND_ACC_PUBLIC)
    PHP_ME(MapField, count,        arginfo_void,      ZEND_ACC_PUBLIC)
    ZEND_FE_END
  };
  
  // -----------------------------------------------------------------------------
  // MapField creation/desctruction
  // -----------------------------------------------------------------------------
  
  zend_class_entry* map_field_type;
  zend_object_handlers* map_field_handlers;
  
  static void map_begin_internal(Map *map, MapIter *iter) {
    iter->self = map;
    upb_strtable_begin(&iter->it, &map->table);
  }
  
  static HashTable *map_field_get_gc(zval *object, zval ***table,
                                          int *n TSRMLS_DC) {
    // TODO(teboring): Unfortunately, zend engine does not support garbage
    // collection for custom array. We have to use zend engine's native array
    // instead.
    *table = NULL;
    *n = 0;
    return NULL;
  }
  
  void map_field_init(TSRMLS_D) {
    zend_class_entry class_type;
    const char* class_name = "Google\\Protobuf\\Internal\\MapField";
    INIT_CLASS_ENTRY_EX(class_type, class_name, strlen(class_name),
                        map_field_methods);
  
    map_field_type = zend_register_internal_class(&class_type TSRMLS_CC);
    map_field_type->create_object = map_field_create;
  
    zend_class_implements(map_field_type TSRMLS_CC, 2, spl_ce_ArrayAccess,
                          spl_ce_Countable);
  
    map_field_handlers = PEMALLOC(zend_object_handlers);
    memcpy(map_field_handlers, zend_get_std_object_handlers(),
           sizeof(zend_object_handlers));
    map_field_handlers->get_gc = map_field_get_gc;
  }
  
  zend_object_value map_field_create(zend_class_entry *ce TSRMLS_DC) {
    zend_object_value retval = {0};
    Map *intern;
  
    intern = emalloc(sizeof(Map));
    memset(intern, 0, sizeof(Map));
  
    zend_object_std_init(&intern->std, ce TSRMLS_CC);
    object_properties_init(&intern->std, ce);
  
    // Table value type is always UINT64: this ensures enough space to store the
    // native_slot value.
    if (!upb_strtable_init(&intern->table, UPB_CTYPE_UINT64)) {
      zend_error(E_USER_ERROR, "Could not allocate table.");
    }
  
    retval.handle = zend_objects_store_put(
        intern, (zend_objects_store_dtor_t)zend_objects_destroy_object,
        (zend_objects_free_object_storage_t)map_field_free, NULL TSRMLS_CC);
    retval.handlers = map_field_handlers;
  
    return retval;
  }
  
  void map_field_free(void *object TSRMLS_DC) {
    Map *map = (Map *)object;
  
    switch (map->value_type) {
      case UPB_TYPE_MESSAGE:
      case UPB_TYPE_STRING:
      case UPB_TYPE_BYTES: {
        MapIter it;
        int len;
        for (map_begin_internal(map, &it); !map_done(&it); map_next(&it)) {
          upb_value value = map_iter_value(&it, &len);
          void *mem = upb_value_memory(&value);
          zval_ptr_dtor(mem);
        }
        break;
      }
      default:
        break;
    }
  
    upb_strtable_uninit(&map->table);
    zend_object_std_dtor(&map->std TSRMLS_CC);
    efree(object);
  }
  
  void map_field_create_with_type(zend_class_entry *ce, const upb_fielddef *field,
                                  zval **map_field TSRMLS_DC) {
    MAKE_STD_ZVAL(*map_field);
    Z_TYPE_PP(map_field) = IS_OBJECT;
    Z_OBJVAL_PP(map_field) =
        map_field_type->create_object(map_field_type TSRMLS_CC);
  
    Map* intern =
        (Map*)zend_object_store_get_object(*map_field TSRMLS_CC);
  
    const upb_fielddef *key_field = map_field_key(field);
    const upb_fielddef *value_field = map_field_value(field);
    intern->key_type = upb_fielddef_type(key_field);
    intern->value_type = upb_fielddef_type(value_field);
    intern->msg_ce = field_type_class(value_field TSRMLS_CC);
  }
  
  static void map_field_free_element(void *object) {
  }
  
  // -----------------------------------------------------------------------------
  // MapField Handlers
  // -----------------------------------------------------------------------------
  
  static bool map_field_read_dimension(zval *object, zval *key, int type,
                                       zval **retval TSRMLS_DC) {
    Map *intern =
        (Map *)zend_object_store_get_object(object TSRMLS_CC);
  
    char keybuf[TABLE_KEY_BUF_LENGTH];
    const char* keyval = NULL;
    size_t length = 0;
    upb_value v;
  #ifndef NDEBUG
    v.ctype = UPB_CTYPE_UINT64;
  #endif
    if (!table_key(intern, key, keybuf, &keyval, &length TSRMLS_CC)) {
      return false;
    }
  
    if (upb_strtable_lookup2(&intern->table, keyval, length, &v)) {
      void* mem = upb_value_memory(&v);
      native_slot_get(intern->value_type, mem, retval TSRMLS_CC);
      return true;
    } else {
      zend_error(E_USER_ERROR, "Given key doesn't exist.");
      return false;
    }
  }
  
  bool map_index_set(Map *intern, const char* keyval, int length, upb_value v) {
    // Replace any existing value by issuing a 'remove' operation first.
    upb_strtable_remove2(&intern->table, keyval, length, NULL);
    if (!upb_strtable_insert2(&intern->table, keyval, length, v)) {
      zend_error(E_USER_ERROR, "Could not insert into table");
      return false;
    }
    return true;
  }
  
  static bool map_field_write_dimension(zval *object, zval *key,
                                        zval *value TSRMLS_DC) {
    Map *intern = (Map *)zend_object_store_get_object(object TSRMLS_CC);
  
    char keybuf[TABLE_KEY_BUF_LENGTH];
    const char* keyval = NULL;
    size_t length = 0;
    upb_value v;
    void* mem;
    if (!table_key(intern, key, keybuf, &keyval, &length TSRMLS_CC)) {
      return false;
    }
  
    mem = upb_value_memory(&v);
    memset(mem, 0, native_slot_size(intern->value_type));
    if (!native_slot_set(intern->value_type, intern->msg_ce, mem, value
  		      TSRMLS_CC)) {
      return false;
    }
  #ifndef NDEBUG
    v.ctype = UPB_CTYPE_UINT64;
  #endif
  
    // Replace any existing value by issuing a 'remove' operation first.
    upb_strtable_remove2(&intern->table, keyval, length, NULL);
    if (!upb_strtable_insert2(&intern->table, keyval, length, v)) {
      zend_error(E_USER_ERROR, "Could not insert into table");
      return false;
    }
  
    return true;
  }
  
  static bool map_field_unset_dimension(zval *object, zval *key TSRMLS_DC) {
    Map *intern = (Map *)zend_object_store_get_object(object TSRMLS_CC);
  
    char keybuf[TABLE_KEY_BUF_LENGTH];
    const char* keyval = NULL;
    size_t length = 0;
    upb_value v;
    if (!table_key(intern, key, keybuf, &keyval, &length TSRMLS_CC)) {
      return false;
    }
  #ifndef NDEBUG
    v.ctype = UPB_CTYPE_UINT64;
  #endif
  
    upb_strtable_remove2(&intern->table, keyval, length, &v);
  
    return true;
  }
  
  // -----------------------------------------------------------------------------
  // PHP MapField Methods
  // -----------------------------------------------------------------------------
  
  PHP_METHOD(MapField, __construct) {
    long key_type, value_type;
    zend_class_entry* klass = NULL;
  
    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "ll|C", &key_type,
                              &value_type, &klass) == FAILURE) {
      return;
    }
  
    Map* intern =
        (Map*)zend_object_store_get_object(getThis() TSRMLS_CC);
    intern->key_type = to_fieldtype(key_type);
    intern->value_type = to_fieldtype(value_type);
    intern->msg_ce = klass;
  
    // Check that the key type is an allowed type.
    switch (intern->key_type) {
      case UPB_TYPE_INT32:
      case UPB_TYPE_INT64:
      case UPB_TYPE_UINT32:
      case UPB_TYPE_UINT64:
      case UPB_TYPE_BOOL:
      case UPB_TYPE_STRING:
      case UPB_TYPE_BYTES:
        // These are OK.
        break;
      default:
        zend_error(E_USER_ERROR, "Invalid key type for map.");
    }
  }
  
  PHP_METHOD(MapField, offsetExists) {
    zval *key;
    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "z", &key) ==
        FAILURE) {
      return;
    }
  
    Map *intern = (Map *)zend_object_store_get_object(getThis() TSRMLS_CC);
  
    char keybuf[TABLE_KEY_BUF_LENGTH];
    const char* keyval = NULL;
    size_t length = 0;
    upb_value v;
  #ifndef NDEBUG
    v.ctype = UPB_CTYPE_UINT64;
  #endif
    if (!table_key(intern, key, keybuf, &keyval, &length TSRMLS_CC)) {
      RETURN_BOOL(false);
    }
  
    RETURN_BOOL(upb_strtable_lookup2(&intern->table, keyval, length, &v));
  }
  
  PHP_METHOD(MapField, offsetGet) {
    zval *index, *value;
    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "z", &index) ==
        FAILURE) {
      return;
    }
    map_field_read_dimension(getThis(), index, BP_VAR_R,
                             return_value_ptr TSRMLS_CC);
  }
  
  PHP_METHOD(MapField, offsetSet) {
    zval *index, *value;
    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "zz", &index, &value) ==
        FAILURE) {
      return;
    }
    map_field_write_dimension(getThis(), index, value TSRMLS_CC);
  }
  
  PHP_METHOD(MapField, offsetUnset) {
    zval *index;
    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "z", &index) ==
        FAILURE) {
      return;
    }
    map_field_unset_dimension(getThis(), index TSRMLS_CC);
  }
  
  PHP_METHOD(MapField, count) {
    Map *intern =
        (Map *)zend_object_store_get_object(getThis() TSRMLS_CC);
  
    if (zend_parse_parameters_none() == FAILURE) {
      return;
    }
  
    RETURN_LONG(upb_strtable_count(&intern->table));
  }
  
  // -----------------------------------------------------------------------------
  // Map Iterator
  // -----------------------------------------------------------------------------
  
  void map_begin(zval *map_php, MapIter *iter TSRMLS_DC) {
    Map *self = UNBOX(Map, map_php);
    map_begin_internal(self, iter);
  }
  
  void map_next(MapIter *iter) {
    upb_strtable_next(&iter->it);
  }
  
  bool map_done(MapIter *iter) {
    return upb_strtable_done(&iter->it);
  }
  
  const char *map_iter_key(MapIter *iter, int *len) {
    *len = upb_strtable_iter_keylength(&iter->it);
    return upb_strtable_iter_key(&iter->it);
  }
  
  upb_value map_iter_value(MapIter *iter, int *len) {
    *len = native_slot_size(iter->self->value_type);
    return upb_strtable_iter_value(&iter->it);
  }
  