blockly/generators/javascript/javascript_generator.ts

/**
 * @license
 * Copyright 2012 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @file JavaScript code generator class, including helper methods for
 * generating JavaScript for blocks.
 */

// Former goog.module ID: Blockly.JavaScript

import * as Variables from '../../core/variables.js';
import * as stringUtils from '../../core/utils/string.js';
import type {Block} from '../../core/block.js';
import {CodeGenerator} from '../../core/generator.js';
import {Names, NameType} from '../../core/names.js';
import type {Workspace} from '../../core/workspace.js';
import {inputTypes} from '../../core/inputs/input_types.js';

/**
 * Order of operation ENUMs.
 * https://developer.mozilla.org/en/JavaScript/Reference/Operators/Operator_Precedence
 */
// prettier-ignore
export enum Order {
  ATOMIC = 0,            // 0 "" ...
  NEW = 1.1,             // new
  MEMBER = 1.2,          // . []
  FUNCTION_CALL = 2,     // ()
  INCREMENT = 3,         // ++
  DECREMENT = 3,         // --
  BITWISE_NOT = 4.1,     // ~
  UNARY_PLUS = 4.2,      // +
  UNARY_NEGATION = 4.3,  // -
  LOGICAL_NOT = 4.4,     // !
  TYPEOF = 4.5,          // typeof
  VOID = 4.6,            // void
  DELETE = 4.7,          // delete
  AWAIT = 4.8,           // await
  EXPONENTIATION = 5.0,  // **
  MULTIPLICATION = 5.1,  // *
  DIVISION = 5.2,        // /
  MODULUS = 5.3,         // %
  SUBTRACTION = 6.1,     // -
  ADDITION = 6.2,        // +
  BITWISE_SHIFT = 7,     // << >> >>>
  RELATIONAL = 8,        // < <= > >=
  IN = 8,                // in
  INSTANCEOF = 8,        // instanceof
  EQUALITY = 9,          // == != === !==
  BITWISE_AND = 10,      // &
  BITWISE_XOR = 11,      // ^
  BITWISE_OR = 12,       // |
  LOGICAL_AND = 13,      // &&
  LOGICAL_OR = 14,       // ||
  CONDITIONAL = 15,      // ?:
  ASSIGNMENT = 16,       // = += -= **= *= /= %= <<= >>= ...
  YIELD = 17,            // yield
  COMMA = 18,            // ,
  NONE = 99,             // (...)
}

/**
 * JavaScript code generator class.
 */
export class JavascriptGenerator extends CodeGenerator {
  /** List of outer-inner pairings that do NOT require parentheses. */
  ORDER_OVERRIDES: [Order, Order][] = [
    // (foo()).bar -> foo().bar
    // (foo())[0] -> foo()[0]
    [Order.FUNCTION_CALL, Order.MEMBER],
    // (foo())() -> foo()()
    [Order.FUNCTION_CALL, Order.FUNCTION_CALL],
    // (foo.bar).baz -> foo.bar.baz
    // (foo.bar)[0] -> foo.bar[0]
    // (foo[0]).bar -> foo[0].bar
    // (foo[0])[1] -> foo[0][1]
    [Order.MEMBER, Order.MEMBER],
    // (foo.bar)() -> foo.bar()
    // (foo[0])() -> foo[0]()
    [Order.MEMBER, Order.FUNCTION_CALL],

    // !(!foo) -> !!foo
    [Order.LOGICAL_NOT, Order.LOGICAL_NOT],
    // a * (b * c) -> a * b * c
    [Order.MULTIPLICATION, Order.MULTIPLICATION],
    // a + (b + c) -> a + b + c
    [Order.ADDITION, Order.ADDITION],
    // a && (b && c) -> a && b && c
    [Order.LOGICAL_AND, Order.LOGICAL_AND],
    // a || (b || c) -> a || b || c
    [Order.LOGICAL_OR, Order.LOGICAL_OR],
  ];

  /** @param name Name of the language the generator is for. */
  constructor(name = 'JavaScript') {
    super(name);
    this.isInitialized = false;

    // Copy Order values onto instance for backwards compatibility
    // while ensuring they are not part of the publically-advertised
    // API.
    //
    // TODO(#7085): deprecate these in due course.  (Could initially
    // replace data properties with get accessors that call
    // deprecate.warn().)
    for (const key in Order) {
      // Must assign Order[key] to a temporary to get the type guard to work;
      // see https://github.com/microsoft/TypeScript/issues/10530.
      const value = Order[key];
      // Skip reverse-lookup entries in the enum.  Due to
      // https://github.com/microsoft/TypeScript/issues/55713 this (as
      // of TypeScript 5.5.2) actually narrows the type of value to
      // never - but that still allows the following assignment to
      // succeed.
      if (typeof value === 'string') continue;
      (this as unknown as Record<string, Order>)['ORDER_' + key] = value;
    }

    // List of illegal variable names.  This is not intended to be a
    // security feature.  Blockly is 100% client-side, so bypassing
    // this list is trivial.  This is intended to prevent users from
    // accidentally clobbering a built-in object or function.
    //
    // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Lexical_grammar#Keywords
    this.addReservedWords(
      'break,case,catch,class,const,continue,debugger,default,delete,do,' +
        'else,export,extends,finally,for,function,if,import,in,instanceof,' +
        'new,return,super,switch,this,throw,try,typeof,var,void,' +
        'while,with,yield,' +
        'enum,' +
        'implements,interface,let,package,private,protected,public,static,' +
        'await,' +
        'null,true,false,' +
        // Magic variable.
        'arguments,' +
        // Everything in the current environment (835 items in Chrome,
        // 104 in Node).
        Object.getOwnPropertyNames(globalThis).join(','),
    );
  }

  /**
   * Initialise the database of variable names.
   *
   * @param workspace Workspace to generate code from.
   */
  init(workspace: Workspace) {
    super.init(workspace);

    if (!this.nameDB_) {
      this.nameDB_ = new Names(this.RESERVED_WORDS_);
    } else {
      this.nameDB_.reset();
    }

    this.nameDB_.setVariableMap(workspace.getVariableMap());
    this.nameDB_.populateVariables(workspace);
    this.nameDB_.populateProcedures(workspace);

    const defvars = [];
    // Add developer variables (not created or named by the user).
    const devVarList = Variables.allDeveloperVariables(workspace);
    for (let i = 0; i < devVarList.length; i++) {
      defvars.push(
        this.nameDB_.getName(devVarList[i], NameType.DEVELOPER_VARIABLE),
      );
    }

    // Add user variables, but only ones that are being used.
    const variables = Variables.allUsedVarModels(workspace);
    for (let i = 0; i < variables.length; i++) {
      defvars.push(
        this.nameDB_.getName(variables[i].getId(), NameType.VARIABLE),
      );
    }

    // Declare all of the variables.
    if (defvars.length) {
      this.definitions_['variables'] = 'var ' + defvars.join(', ') + ';';
    }
    this.isInitialized = true;
  }

  /**
   * Prepend the generated code with the variable definitions.
   *
   * @param code Generated code.
   * @returns Completed code.
   */
  finish(code: string): string {
    // Convert the definitions dictionary into a list.
    const definitions = Object.values(this.definitions_);
    // Call Blockly.CodeGenerator's finish.
    super.finish(code);
    this.isInitialized = false;

    this.nameDB_!.reset();
    return definitions.join('\n\n') + '\n\n\n' + code;
  }

  /**
   * Naked values are top-level blocks with outputs that aren't plugged into
   * anything.  A trailing semicolon is needed to make this legal.
   *
   * @param line Line of generated code.
   * @returns Legal line of code.
   */
  scrubNakedValue(line: string): string {
    return line + ';\n';
  }

  /**
   * Encode a string as a properly escaped JavaScript string, complete with
   * quotes.
   *
   * @param string Text to encode.
   * @returns JavaScript string.
   */
  quote_(string: string): string {
    // Can't use goog.string.quote since Google's style guide recommends
    // JS string literals use single quotes.
    string = string
      .replace(/\\/g, '\\\\')
      .replace(/\n/g, '\\\n')
      .replace(/'/g, "\\'");
    return "'" + string + "'";
  }

  /**
   * Encode a string as a properly escaped multiline JavaScript string, complete
   * with quotes.
   * @param string Text to encode.
   * @returns JavaScript string.
   */
  multiline_quote_(string: string): string {
    // Can't use goog.string.quote since Google's style guide recommends
    // JS string literals use single quotes.
    const lines = string.split(/\n/g).map(this.quote_);
    return lines.join(" + '\\n' +\n");
  }

  /**
   * Common tasks for generating JavaScript from blocks.
   * Handles comments for the specified block and any connected value blocks.
   * Calls any statements following this block.
   *
   * @param block The current block.
   * @param code The JavaScript code created for this block.
   * @param thisOnly True to generate code for only this statement.
   * @returns JavaScript code with comments and subsequent blocks added.
   * @protected
   */
  scrub_(block: Block, code: string, thisOnly = false): string {
    let commentCode = '';
    // Only collect comments for blocks that aren't inline.
    if (!block.outputConnection || !block.outputConnection.targetConnection) {
      // Collect comment for this block.
      let comment = block.getCommentText();
      if (comment) {
        comment = stringUtils.wrap(comment, this.COMMENT_WRAP - 3);
        commentCode += this.prefixLines(comment + '\n', '// ');
      }
      // Collect comments for all value arguments.
      // Don't collect comments for nested statements.
      for (let i = 0; i < block.inputList.length; i++) {
        if (block.inputList[i].type === inputTypes.VALUE) {
          const childBlock = block.inputList[i].connection!.targetBlock();
          if (childBlock) {
            comment = this.allNestedComments(childBlock);
            if (comment) {
              commentCode += this.prefixLines(comment, '// ');
            }
          }
        }
      }
    }
    const nextBlock =
      block.nextConnection && block.nextConnection.targetBlock();
    const nextCode = thisOnly ? '' : this.blockToCode(nextBlock);
    return commentCode + code + nextCode;
  }

  /**
   * Generate code representing the specified value input, adjusted to take into
   * account indexing (zero- or one-based) and optionally by a specified delta
   * and/or by negation.
   *
   * @param block The block.
   * @param atId The ID of the input block to get (and adjust) the value of.
   * @param delta Value to add.
   * @param negate Whether to negate the value.
   * @param order The highest order acting on this value.
   * @returns The adjusted value or code that evaluates to it.
   */
  getAdjusted(
    block: Block,
    atId: string,
    delta = 0,
    negate = false,
    order = Order.NONE,
  ): string {
    if (block.workspace.options.oneBasedIndex) {
      delta--;
    }
    const defaultAtIndex = block.workspace.options.oneBasedIndex ? '1' : '0';

    let orderForInput = order;
    if (delta > 0) {
      orderForInput = Order.ADDITION;
    } else if (delta < 0) {
      orderForInput = Order.SUBTRACTION;
    } else if (negate) {
      orderForInput = Order.UNARY_NEGATION;
    }

    let at = this.valueToCode(block, atId, orderForInput) || defaultAtIndex;

    // Easy case: no adjustments.
    if (delta === 0 && !negate) {
      return at;
    }
    // If the index is a naked number, adjust it right now.
    if (stringUtils.isNumber(at)) {
      at = String(Number(at) + delta);
      if (negate) {
        at = String(-Number(at));
      }
      return at;
    }
    // If the index is dynamic, adjust it in code.
    if (delta > 0) {
      at = `${at} + ${delta}`;
    } else if (delta < 0) {
      at = `${at} - ${-delta}`;
    }
    if (negate) {
      at = delta ? `-(${at})` : `-${at}`;
    }
    if (Math.floor(order) >= Math.floor(orderForInput)) {
      at = `(${at})`;
    }
    return at;
  }
}