Convert syntax between languages

syntax_convert.js

/* Note: 
     This is not meant for translating real code between languages.
     Only for basic syntax translation, to get you started with a skeleton,
       before doing line-by-line manually 
*/

var Converter = {
    
  curlifyWhitespace: function (code) {
  
    var lines = code.split('\n');
    var o = '';
    var nextLine;
    var ws1, ws2, wsp;
    var wsStack = [];
    
    for (var i = 0, llen = lines.length; i < llen ; i++) {
      // Find whitespace length of current line
      ws1 = lines[i].match(/^\s*/)[0];
    
      // Find next line
      for (nextLine = i + 1; nextLine < llen; nextLine++) {
        if (lines[nextLine].trim().length === 0) continue;
        break;
      }
    
      // Find whitespace length of next line
      ws2 = (nextLine === llen ? '' : lines[nextLine]).match(/^\s*/)[0];
    
      if (lines[i].trim().length === 0) {
        // Empty line
        o += lines[i] + '\n';
      } else {
        if (ws1 === ws2) {
          // Same level
          o += lines[i] + '\n';
        } else {
          // Different level
          if (ws2.length > ws1.length) {
            // Next line is a higher level, open a block
            o += lines[i] + '{\n';
            wsStack.push(ws1);
          } else if (ws2.length < ws1.length) {
            // Next line is a lower level, close all blocks until that level
            o += lines[i] + '\n';
            while (wsStack.length && wsStack[wsStack.length - 1] >= ws2) {
              o += wsStack.pop() + '}\n'
            }
          } else {
            // Should not arrive here!
            o += lines[i];
            console.warn('Different characters used in block whitespace!')
          }
        }
      }
    }
    
    return o;
  },
  
  convertPythonCommentsToJs: function (code) {
    return code
        .replace(/(^|\r|\n)(\s*)#([^\r\n]*)/g, '$1$2//$3')
        .replace(/^(\s*)(["']{3})(|[\s\S]*?(?:[^\\](?:(\\)\4)*))\2/gm, function () { return arguments[1] + '/*' + arguments[3].replace(/\*\//g, '* /') + '*/' });
  },
  
  python2js: function (code) {
    
    // Convert comments
    code = this.convertPythonCommentsToJs(code);
    
    // Add curly braces
    code = this.curlifyWhitespace(code);
    
    // Finalize function definitions
    code = code
        .replace(/(\s*)def\s+([a-zA-Z0-9_]+)\s*\(\s*self\s*(?:,\s*([^)]+))?\)\s*:\s*{/g, '$1function $2($3) {')
        .replace(/(\s*)def\s+([a-zA-Z0-9_]+)\s*\((?:\s*([^)]+))?\)\s*:\s*{/g, '$1function $2($3) {');
    
    // Convert some fors
    code = code.replace(/^([ \t]*)for ([a-zA-Z]+) in range\((.+?)\)\s*:/gm, '$1for (var $2 = 0, $2len = $3; $2 < $2len; $2++) ');
    
    // Convert ifs
    code = code
        .replace(/^([ \t]*)if (.+?)\s*:/gm, '$1if ($2) ')
        .replace(/^([ \t]*)else\s*:/gm, '$1else ')
        .replace(/^([ \t]*)elif\s*(.+?)\s*:/gm, '$1else if ($2) ');
    
    // Convert try-except-finally
    code = code
        .replace(/^([ \t]*)try\s*:/gm, '$1try ')
        .replace(/^([ \t]*)except (.+?)\s*:/gm, '$1catch ($2) ')
        .replace(/^([ \t]*)finally\s*:/gm, '$1finally ');
    
    return code;
  }
  
};