blockly/generators/dart/dart_generator.ts

/**
 * @license
 * Copyright 2014 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

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

// Former goog.module ID: Blockly.Dart

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

/**
 * Order of operation ENUMs.
 * https://dart.dev/guides/language/language-tour#operators
 */
// prettier-ignore
export enum Order {
  ATOMIC = 0,         // 0 "" ...
  UNARY_POSTFIX = 1,  // expr++ expr-- () [] . ?.
  UNARY_PREFIX = 2,   // -expr !expr ~expr ++expr --expr
  MULTIPLICATIVE = 3, // * / % ~/
  ADDITIVE = 4,       // + -
  SHIFT = 5,          // << >>
  BITWISE_AND = 6,    // &
  BITWISE_XOR = 7,    // ^
  BITWISE_OR = 8,     // |
  RELATIONAL = 9,     // >= > <= < as is is!
  EQUALITY = 10,      // == !=
  LOGICAL_AND = 11,   // &&
  LOGICAL_OR = 12,    // ||
  IF_NULL = 13,       // ??
  CONDITIONAL = 14,   // expr ? expr: expr
  CASCADE = 15,       // ..
  ASSIGNMENT = 16,    // = *= /= ~/= %= += -= <<= >>= &= ^= |=
  NONE = 99,          // (...)
}

/**
 * Dart code generator class.
 */
export class DartGenerator extends CodeGenerator {
  /** @param name Name of the language the generator is for. */
  constructor(name = 'Dart') {
    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.
    this.addReservedWords(
      // https://www.dartlang.org/docs/spec/latest/dart-language-specification.pdf
      // Section 16.1.1
      'assert,break,case,catch,class,const,continue,default,do,else,enum,' +
        'extends,false,final,finally,for,if,in,is,new,null,rethrow,return,' +
        'super,switch,this,throw,true,try,var,void,while,with,' +
        // https://api.dartlang.org/dart_core.html
        'print,identityHashCode,identical,BidirectionalIterator,Comparable,' +
        'double,Function,int,Invocation,Iterable,Iterator,List,Map,Match,num,' +
        'Pattern,RegExp,Set,StackTrace,String,StringSink,Type,bool,DateTime,' +
        'Deprecated,Duration,Expando,Null,Object,RuneIterator,Runes,Stopwatch,' +
        'StringBuffer,Symbol,Uri,Comparator,AbstractClassInstantiationError,' +
        'ArgumentError,AssertionError,CastError,ConcurrentModificationError,' +
        'CyclicInitializationError,Error,Exception,FallThroughError,' +
        'FormatException,IntegerDivisionByZeroException,NoSuchMethodError,' +
        'NullThrownError,OutOfMemoryError,RangeError,StackOverflowError,' +
        'StateError,TypeError,UnimplementedError,UnsupportedError',
    );
  }

  /**
   * 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 import statements and variable definitions.
   *
   * @param code Generated code.
   * @returns Completed code.
   */
  finish(code: string): string {
    // Indent every line.
    if (code) {
      code = this.prefixLines(code, this.INDENT);
    }
    code = 'main() {\n' + code + '}';

    // Convert the definitions dictionary into a list.
    const imports = [];
    const definitions = [];
    for (let name in this.definitions_) {
      const def = this.definitions_[name];
      if (def.match(/^import\s/)) {
        imports.push(def);
      } else {
        definitions.push(def);
      }
    }
    // Call Blockly.CodeGenerator's finish.
    code = super.finish(code);
    this.isInitialized = false;

    this.nameDB_!.reset();
    const allDefs = imports.join('\n') + '\n\n' + definitions.join('\n\n');
    return allDefs.replace(/\n\n+/g, '\n\n').replace(/\n*$/, '\n\n\n') + code;
  }

  /**
   * Naked values are top-level blocks with outputs that aren't plugged into
   * anything.
   *
   * @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 Dart string, complete with quotes.
   *
   * @param string Text to encode.
   * @returns Dart string.
   */
  quote_(string: string): string {
    // Can't use goog.string.quote since $ must also be escaped.
    string = string
      .replace(/\\/g, '\\\\')
      .replace(/\n/g, '\\\n')
      .replace(/\$/g, '\\$')
      .replace(/'/g, "\\'");
    return "'" + string + "'";
  }

  /**
   * Encode a string as a properly escaped multiline Dart string, complete
   * with quotes.
   *
   * @param string Text to encode.
   * @returns Dart string.
   */
  multiline_quote_(string: string): string {
    const lines = string.split(/\n/g).map(this.quote_);
    // Join with the following, plus a newline:
    // + '\n' +
    return lines.join(" + '\\n' + \n");
  }

  /**
   * Common tasks for generating Dart 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 Dart code created for this block.
   * @param thisOnly True to generate code for only this statement.
   * @returns Dart code with comments and subsequent blocks added.
   */
  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);
        if ((block as AnyDuringMigration).getProcedureDef) {
          // Use documentation comment for function comments.
          commentCode += this.prefixLines(comment + '\n', '/// ');
        } else {
          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) {
      orderForInput = Order.ADDITIVE;
    } else if (negate) {
      orderForInput = Order.UNARY_PREFIX;
    }

    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;
  }
}