Files
blockly/core/field_registry.js
2019-08-16 09:57:28 -07:00

94 lines
3.3 KiB
JavaScript

/**
* @license
* Visual Blocks Editor
*
* Copyright 2019 Google Inc.
* https://developers.google.com/blockly/
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @fileoverview Fields can be created based on a JSON definition. This file
* contains methods for registering those JSON definitions, and building the
* fields based on JSON.
* @author bekawestberg@gmail.com (Beka Westberg)
*/
'use strict';
/**
* @name Blockly.fieldRegistry
* @namespace
*/
goog.provide('Blockly.fieldRegistry');
/**
* The set of all registered fields, keyed by field type as used in the JSON
* definition of a block.
* @type {!Object<string, !{fromJson: Function}>}
* @private
*/
Blockly.fieldRegistry.typeMap_ = {};
/**
* Registers a field type. May also override an existing field type.
* Blockly.fieldRegistry.fromJson uses this registry to
* find the appropriate field type.
* @param {string} type The field type name as used in the JSON definition.
* @param {!{fromJson: Function}} fieldClass The field class containing a
* fromJson function that can construct an instance of the field.
* @throws {Error} if the type name is empty, or the fieldClass is not an
* object containing a fromJson function.
*/
Blockly.fieldRegistry.register = function(type, fieldClass) {
if ((typeof type != 'string') || (type.trim() == '')) {
throw Error('Invalid field type "' + type + '". The type must be a' +
' non-empty string.');
}
if (!fieldClass || (typeof fieldClass.fromJson != 'function')) {
throw Error('Field "' + fieldClass + '" must have a fromJson function');
}
Blockly.fieldRegistry.typeMap_[type] = fieldClass;
};
/**
* Construct a Field from a JSON arg object.
* Finds the appropriate registered field by the type name as registered using
* Blockly.fieldRegistry.register.
* @param {!Object} options A JSON object with a type and options specific
* to the field type.
* @return {Blockly.Field} The new field instance or null if a field wasn't
* found with the given type name
* @package
*/
Blockly.fieldRegistry.fromJson = function(options) {
var fieldClass = Blockly.fieldRegistry.typeMap_[options['type']];
if (!fieldClass) {
console.warn('Blockly could not create a field of type ' + options['type'] +
'. The field is probably not being registered. This could be because' +
' the file is not loaded, the field does not register itself (See:' +
' github.com/google/blockly/issues/1584), or the registration is not' +
' being reached.');
return null;
}
var field = fieldClass.fromJson(options);
if (options['tooltip'] !== undefined) {
var rawValue = options['tooltip'];
var localizedText = Blockly.utils.replaceMessageReferences(rawValue);
field.setTooltip(localizedText);
}
return field;
};