blockly/generators/python/python_generator.ts

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

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

// Former goog.module ID: Blockly.Python

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

/**
 * Order of operation ENUMs.
 * http://docs.python.org/reference/expressions.html#summary
 */
// prettier-ignore
export enum Order {
  ATOMIC = 0,             // 0 "" ...
  COLLECTION = 1,         // tuples, lists, dictionaries
  STRING_CONVERSION = 1,  // `expression...`
  MEMBER = 2.1,           // . []
  FUNCTION_CALL = 2.2,    // ()
  EXPONENTIATION = 3,     // **
  UNARY_SIGN = 4,         // + -
  BITWISE_NOT = 4,        // ~
  MULTIPLICATIVE = 5,     // * / // %
  ADDITIVE = 6,           // + -
  BITWISE_SHIFT = 7,      // << >>
  BITWISE_AND = 8,        // &
  BITWISE_XOR = 9,        // ^
  BITWISE_OR = 10,        // |
  RELATIONAL = 11,        // in, not in, is, is not, >, >=, <>, !=, ==
  LOGICAL_NOT = 12,       // not
  LOGICAL_AND = 13,       // and
  LOGICAL_OR = 14,        // or
  CONDITIONAL = 15,       // if else
  LAMBDA = 16,            // lambda
  NONE = 99,              // (...)
}

/**
 * PythonScript code generator class.
 */
export class PythonGenerator 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],

    // not (not foo) -> not not foo
    [Order.LOGICAL_NOT, Order.LOGICAL_NOT],
    // a and (b and c) -> a and b and c
    [Order.LOGICAL_AND, Order.LOGICAL_AND],
    // a or (b or c) -> a or b or c
    [Order.LOGICAL_OR, Order.LOGICAL_OR],
  ];

  /**
   * Empty loops or conditionals are not allowed in Python.
   */
  PASS: string = ''; // Initialised by init().

  /** @param name Name of the language the generator is for. */
  constructor(name = 'Python') {
    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(
      // import keyword
      // print(','.join(sorted(keyword.kwlist)))
      // https://docs.python.org/3/reference/lexical_analysis.html#keywords
      // https://docs.python.org/2/reference/lexical_analysis.html#keywords
      'False,None,True,and,as,assert,break,class,continue,def,del,elif,else,' +
        'except,exec,finally,for,from,global,if,import,in,is,lambda,nonlocal,' +
        'not,or,pass,print,raise,return,try,while,with,yield,' +
        // https://docs.python.org/3/library/constants.html
        // https://docs.python.org/2/library/constants.html
        'NotImplemented,Ellipsis,__debug__,quit,exit,copyright,license,credits,' +
        // >>> print(','.join(sorted(dir(__builtins__))))
        // https://docs.python.org/3/library/functions.html
        // https://docs.python.org/2/library/functions.html
        'ArithmeticError,AssertionError,AttributeError,BaseException,' +
        'BlockingIOError,BrokenPipeError,BufferError,BytesWarning,' +
        'ChildProcessError,ConnectionAbortedError,ConnectionError,' +
        'ConnectionRefusedError,ConnectionResetError,DeprecationWarning,' +
        'EOFError,Ellipsis,EnvironmentError,Exception,FileExistsError,' +
        'FileNotFoundError,FloatingPointError,FutureWarning,GeneratorExit,' +
        'IOError,ImportError,ImportWarning,IndentationError,IndexError,' +
        'InterruptedError,IsADirectoryError,KeyError,KeyboardInterrupt,' +
        'LookupError,MemoryError,ModuleNotFoundError,NameError,' +
        'NotADirectoryError,NotImplemented,NotImplementedError,OSError,' +
        'OverflowError,PendingDeprecationWarning,PermissionError,' +
        'ProcessLookupError,RecursionError,ReferenceError,ResourceWarning,' +
        'RuntimeError,RuntimeWarning,StandardError,StopAsyncIteration,' +
        'StopIteration,SyntaxError,SyntaxWarning,SystemError,SystemExit,' +
        'TabError,TimeoutError,TypeError,UnboundLocalError,UnicodeDecodeError,' +
        'UnicodeEncodeError,UnicodeError,UnicodeTranslateError,UnicodeWarning,' +
        'UserWarning,ValueError,Warning,ZeroDivisionError,_,__build_class__,' +
        '__debug__,__doc__,__import__,__loader__,__name__,__package__,__spec__,' +
        'abs,all,any,apply,ascii,basestring,bin,bool,buffer,bytearray,bytes,' +
        'callable,chr,classmethod,cmp,coerce,compile,complex,copyright,credits,' +
        'delattr,dict,dir,divmod,enumerate,eval,exec,execfile,exit,file,filter,' +
        'float,format,frozenset,getattr,globals,hasattr,hash,help,hex,id,input,' +
        'int,intern,isinstance,issubclass,iter,len,license,list,locals,long,' +
        'map,max,memoryview,min,next,object,oct,open,ord,pow,print,property,' +
        'quit,range,raw_input,reduce,reload,repr,reversed,round,set,setattr,' +
        'slice,sorted,staticmethod,str,sum,super,tuple,type,unichr,unicode,' +
        'vars,xrange,zip',
    );
  }

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

    this.PASS = this.INDENT + 'pass\n';

    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], Names.DEVELOPER_VARIABLE_TYPE) +
          ' = None',
      );
    }

    // 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.getVariableName(variables[i].getId()) + ' = None');
    }

    this.definitions_['variables'] = defvars.join('\n');
    this.isInitialized = true;
  }

  /**
   * Prepend the generated code with import statements and variable definitions.
   *
   * @param code Generated code.
   * @returns Completed code.
   */
  finish(code: string): string {
    // 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(/^(from\s+\S+\s+)?import\s+\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 Python string, complete with quotes.
   *
   * @param string Text to encode.
   * @returns Python string.
   */
  quote_(string: string): string {
    string = string.replace(/\\/g, '\\\\').replace(/\n/g, '\\\n');

    // Follow the CPython behaviour of repr() for a non-byte string.
    let quote = "'";
    if (string.indexOf("'") !== -1) {
      if (string.indexOf('"') === -1) {
        quote = '"';
      } else {
        string = string.replace(/'/g, "\\'");
      }
    }
    return quote + string + quote;
  }

  /**
   * Encode a string as a properly escaped multiline Python string, complete
   * with quotes.
   *
   * @param string Text to encode.
   * @returns Python 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 Python 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 Python code created for this block.
   * @param thisOnly True to generate code for only this statement.
   * @returns Python 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);
        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;
  }

  /**
   * Gets a property and adjusts the value, taking into account indexing.
   * If a static int, casts to an integer, otherwise returns a code string.
   *
   * @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.
   * @returns The adjusted value or code that evaluates to it.
   */
  getAdjustedInt(
    block: Block,
    atId: string,
    delta = 0,
    negate = false,
  ): string | number {
    if (block.workspace.options.oneBasedIndex) {
      delta--;
    }
    const defaultAtIndex = block.workspace.options.oneBasedIndex ? '1' : '0';
    const atOrder = delta ? Order.ADDITIVE : Order.NONE;
    let at: string | number =
      this.valueToCode(block, atId, atOrder) || defaultAtIndex;

    if (stringUtils.isNumber(at)) {
      // If the index is a naked number, adjust it right now.
      at = parseInt(at, 10) + delta;
      if (negate) {
        at = -at;
      }
    } else {
      // If the index is dynamic, adjust it in code.
      if (delta > 0) {
        at = 'int(' + at + ' + ' + delta + ')';
      } else if (delta < 0) {
        at = 'int(' + at + ' - ' + -delta + ')';
      } else {
        at = 'int(' + at + ')';
      }
      if (negate) {
        at = '-' + at;
      }
    }
    return at;
  }
}