core/generator.js
/**
* @license
* Visual Blocks Editor
*
* Copyright 2012 Google Inc.
* https://blockly.googlecode.com/
*
* 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 Utility functions for generating executable code from
* Blockly code.
* @author fraser@google.com (Neil Fraser)
*/
'use strict';
goog.provide('Blockly.Generator');
goog.require('Blockly.Block');
/**
* Class for a code generator that translates the blocks into a language.
* @param {string} name Language name of this generator.
* @constructor
*/
Blockly.Generator = function(name) {
this.name_ = name;
this.RESERVED_WORDS_ = '';
};
/**
* Category to separate generated function names from variables and procedures.
*/
Blockly.Generator.NAME_TYPE = 'generated_function';
/**
* Arbitrary code to inject into locations that risk causing infinite loops.
* Any instances of '%1' will be replaced by the block ID that failed.
* E.g. ' checkTimeout(%1);\n'
* @type ?string
*/
Blockly.Generator.prototype.INFINITE_LOOP_TRAP = null;
/**
* Arbitrary code to inject before every statement.
* Any instances of '%1' will be replaced by the block ID of the statement.
* E.g. 'highlight(%1);\n'
* @type ?string
*/
Blockly.Generator.prototype.STATEMENT_PREFIX = null;
/**
* Generate code for all blocks in the workspace to the specified language.
* @return {string} Generated code.
*/
Blockly.Generator.prototype.workspaceToCode = function() {
var code = [];
this.init();
var blocks = Blockly.mainWorkspace.getTopBlocks(true);
for (var x = 0, block; block = blocks[x]; x++) {
var line = this.blockToCode(block);
if (goog.isArray(line)) {
// Value blocks return tuples of code and operator order.
// Top-level blocks don't care about operator order.
line = line[0];
}
if (line) {
if (block.outputConnection && this.scrubNakedValue) {
// This block is a naked value. Ask the language's code generator if
// it wants to append a semicolon, or something.
line = this.scrubNakedValue(line);
}
code.push(line);
}
}
code = code.join('\n'); // Blank line between each section.
code = this.finish(code);
// Final scrubbing of whitespace.
code = code.replace(/^\s+\n/, '');
code = code.replace(/\n\s+$/, '\n');
code = code.replace(/[ \t]+\n/g, '\n');
return code;
};
// The following are some helpful functions which can be used by multiple
// languages.
/**
* Prepend a common prefix onto each line of code.
* @param {string} text The lines of code.
* @param {string} prefix The common prefix.
* @return {string} The prefixed lines of code.
*/
Blockly.Generator.prototype.prefixLines = function(text, prefix) {
return prefix + text.replace(/\n(.)/g, '\n' + prefix + '$1');
};
/**
* Recursively spider a tree of blocks, returning all their comments.
* @param {!Blockly.Block} block The block from which to start spidering.
* @return {string} Concatenated list of comments.
*/
Blockly.Generator.prototype.allNestedComments = function(block) {
var comments = [];
var blocks = block.getDescendants();
for (var x = 0; x < blocks.length; x++) {
var comment = blocks[x].getCommentText();
if (comment) {
comments.push(comment);
}
}
// Append an empty string to create a trailing line break when joined.
if (comments.length) {
comments.push('');
}
return comments.join('\n');
};
/**
* Generate code for the specified block (and attached blocks).
* @param {Blockly.Block} block The block to generate code for.
* @return {string|!Array} For statement blocks, the generated code.
* For value blocks, an array containing the generated code and an
* operator order value. Returns '' if block is null.
*/
Blockly.Generator.prototype.blockToCode = function(block) {
if (!block) {
return '';
}
if (block.disabled) {
// Skip past this block if it is disabled.
return this.blockToCode(block.getNextBlock());
}
var func = this[block.type];
if (!func) {
throw 'Language "' + this.name_ + '" does not know how to generate code ' +
'for block type "' + block.type + '".';
}
// First argument to func.call is the value of 'this' in the generator.
// Prior to 24 September 2013 'this' was the only way to access the block.
// The current prefered method of accessing the block is through the second
// argument to func.call, which becomes the first parameter to the generator.
var code = func.call(block, block);
if (goog.isArray(code)) {
// Value blocks return tuples of code and operator order.
return [this.scrub_(block, code[0]), code[1]];
} else if (goog.isString(code)) {
if (this.STATEMENT_PREFIX) {
code = this.STATEMENT_PREFIX.replace(/%1/g, '\'' + block.id + '\'') +
code;
}
return this.scrub_(block, code);
} else if (code === null) {
// Block has handled code generation itself.
return '';
} else {
throw 'Invalid code generated: ' + code;
}
};
/**
* Generate code representing the specified value input.
* @param {!Blockly.Block} block The block containing the input.
* @param {string} name The name of the input.
* @param {number} order The maximum binding strength (minimum order value)
* of any operators adjacent to "block".
* @return {string} Generated code or '' if no blocks are connected or the
* specified input does not exist.
*/
Blockly.Generator.prototype.valueToCode = function(block, name, order) {
if (isNaN(order)) {
throw 'Expecting valid order from block "' + block.type + '".';
}
var targetBlock = block.getInputTargetBlock(name);
if (!targetBlock) {
return '';
}
var tuple = this.blockToCode(targetBlock);
if (tuple === '') {
// Disabled block.
return '';
}
if (!goog.isArray(tuple)) {
// Value blocks must return code and order of operations info.
// Statement blocks must only return code.
throw 'Expecting tuple from value block "' + targetBlock.type + '".';
}
var code = tuple[0];
var innerOrder = tuple[1];
if (isNaN(innerOrder)) {
throw 'Expecting valid order from value block "' + targetBlock.type + '".';
}
if (code && order <= innerOrder) {
if (order == innerOrder || (order == 0 || order == 99)) {
// 0 is the atomic order, 99 is the none order. No parentheses needed.
// In all known languages multiple such code blocks are not order
// sensitive. In fact in Python ('a' 'b') 'c' would fail.
} else {
// The operators outside this code are stonger than the operators
// inside this code. To prevent the code from being pulled apart,
// wrap the code in parentheses.
// Technically, this should be handled on a language-by-language basis.
// However all known (sane) languages use parentheses for grouping.
code = '(' + code + ')';
}
}
return code;
};
/**
* Generate code representing the statement. Indent the code.
* @param {!Blockly.Block} block The block containing the input.
* @param {string} name The name of the input.
* @return {string} Generated code or '' if no blocks are connected.
*/
Blockly.Generator.prototype.statementToCode = function(block, name) {
var targetBlock = block.getInputTargetBlock(name);
var code = this.blockToCode(targetBlock);
if (!goog.isString(code)) {
// Value blocks must return code and order of operations info.
// Statement blocks must only return code.
throw 'Expecting code from statement block "' + targetBlock.type + '".';
}
if (code) {
code = this.prefixLines(/** @type {string} */ (code), this.INDENT);
}
return code;
};
/**
* Add an infinite loop trap to the contents of a loop.
* If loop is empty, add a statment prefix for the loop block.
* @param {string} branch Code for loop contents.
* @param {string} id ID of enclosing block.
* @return {string} Loop contents, with infinite loop trap added.
*/
Blockly.Generator.prototype.addLoopTrap = function(branch, id) {
if (this.INFINITE_LOOP_TRAP) {
branch = this.INFINITE_LOOP_TRAP.replace(/%1/g, '\'' + id + '\'') + branch;
}
if (this.STATEMENT_PREFIX) {
branch += this.prefixLines(this.STATEMENT_PREFIX.replace(/%1/g,
'\'' + id + '\''), this.INDENT);
}
return branch;
};
/**
* The method of indenting. Defaults to two spaces, but language generators
* may override this to increase indent or change to tabs.
*/
Blockly.Generator.prototype.INDENT = ' ';
/**
* Add one or more words to the list of reserved words for this language.
* @param {string} words Comma-separated list of words to add to the list.
* No spaces. Duplicates are ok.
*/
Blockly.Generator.prototype.addReservedWords = function(words) {
this.RESERVED_WORDS_ += words + ',';
};
/**
* This is used as a placeholder in functions defined using
* Blockly.Generator.provideFunction_. It must not be legal code that could
* legitimately appear in a function definition (or comment), and it must
* not confuse the regular expression parser.
*/
Blockly.Generator.prototype.FUNCTION_NAME_PLACEHOLDER_ = '{leCUI8hutHZI4480Dc}';
Blockly.Generator.prototype.FUNCTION_NAME_PLACEHOLDER_REGEXP_ =
new RegExp(Blockly.Generator.prototype.FUNCTION_NAME_PLACEHOLDER_, 'g');
/**
* Define a function to be included in the generated code.
* The first time this is called with a given desiredName, the code is
* saved and an actual name is generated. Subsequent calls with the
* same desiredName have no effect but have the same return value.
*
* It is up to the caller to make sure the same desiredName is not
* used for different code values.
*
* The code gets output when Blockly.Generator.finish() is called.
*
* @param {string} desiredName The desired name of the function (e.g., isPrime).
* @param {!Array.<string>} code A list of Python statements.
* @return {string} The actual name of the new function. This may differ
* from desiredName if the former has already been taken by the user.
* @private
*/
Blockly.Generator.prototype.provideFunction_ = function(desiredName, code) {
if (!this.definitions_[desiredName]) {
var functionName =
this.variableDB_.getDistinctName(desiredName, this.NAME_TYPE);
this.functionNames_[desiredName] = functionName;
this.definitions_[desiredName] = code.join('\n').replace(
this.FUNCTION_NAME_PLACEHOLDER_REGEXP_, functionName);
}
return this.functionNames_[desiredName];
};