Blockly.utils.tokenizeInterpolation_ = function()

in core/utils.js [278:405]

• 109 lines of code
• 29 McCabe index (conditional complexity)

Blockly.utils.tokenizeInterpolation_ = function(message,
    parseInterpolationTokens) {
  var tokens = [];
  var chars = message.split('');
  chars.push('');  // End marker.
  // Parse the message with a finite state machine.
  // 0 - Base case.
  // 1 - % found.
  // 2 - Digit found.
  // 3 - Message ref found.
  var state = 0;
  var buffer = [];
  var number = null;
  for (var i = 0; i < chars.length; i++) {
    var c = chars[i];
    if (state == 0) {
      if (c == '%') {
        var text = buffer.join('');
        if (text) {
          tokens.push(text);
        }
        buffer.length = 0;
        state = 1;  // Start escape.
      } else {
        buffer.push(c);  // Regular char.
      }
    } else if (state == 1) {
      if (c == '%') {
        buffer.push(c);  // Escaped %: %%
        state = 0;
      } else if (parseInterpolationTokens && '0' <= c && c <= '9') {
        state = 2;
        number = c;
        var text = buffer.join('');
        if (text) {
          tokens.push(text);
        }
        buffer.length = 0;
      } else if (c == '{') {
        state = 3;
      } else {
        buffer.push('%', c);  // Not recognized. Return as literal.
        state = 0;
      }
    } else if (state == 2) {
      if ('0' <= c && c <= '9') {
        number += c;  // Multi-digit number.
      } else {
        tokens.push(parseInt(number, 10));
        i--;  // Parse this char again.
        state = 0;
      }
    } else if (state == 3) {  // String table reference
      if (c == '') {
        // Premature end before closing '}'
        buffer.splice(0, 0, '%{');  // Re-insert leading delimiter
        i--;  // Parse this char again.
        state = 0;  // and parse as string literal.
      } else if (c != '}') {
        buffer.push(c);
      } else {
        var rawKey = buffer.join('');
        if (/[A-Z]\w*/i.test(rawKey)) {  // Strict matching
          // Found a valid string key. Attempt case insensitive match.
          var keyUpper = rawKey.toUpperCase();

          // BKY_ is the prefix used to namespace the strings used in Blockly
          // core files and the predefined blocks in ../blocks/.
          // These strings are defined in ../msgs/ files.
          var bklyKey = Blockly.utils.string.startsWith(keyUpper, 'BKY_') ?
              keyUpper.substring(4) : null;
          if (bklyKey && bklyKey in Blockly.Msg) {
            var rawValue = Blockly.Msg[bklyKey];
            if (typeof rawValue == 'string') {
              // Attempt to dereference substrings, too, appending to the end.
              Array.prototype.push.apply(tokens,
                  Blockly.utils.tokenizeInterpolation_(
                      rawValue, parseInterpolationTokens));
            } else if (parseInterpolationTokens) {
              // When parsing interpolation tokens, numbers are special
              // placeholders (%1, %2, etc). Make sure all other values are
              // strings.
              tokens.push(String(rawValue));
            } else {
              tokens.push(rawValue);
            }
          } else {
            // No entry found in the string table. Pass reference as string.
            tokens.push('%{' + rawKey + '}');
          }
          buffer.length = 0;  // Clear the array
          state = 0;
        } else {
          tokens.push('%{' + rawKey + '}');
          buffer.length = 0;
          state = 0;  // and parse as string literal.
        }
      }
    }
  }
  var text = buffer.join('');
  if (text) {
    tokens.push(text);
  }

  // Merge adjacent text tokens into a single string.
  var mergedTokens = [];
  buffer.length = 0;
  for (var i = 0; i < tokens.length; ++i) {
    if (typeof tokens[i] == 'string') {
      buffer.push(tokens[i]);
    } else {
      text = buffer.join('');
      if (text) {
        mergedTokens.push(text);
      }
      buffer.length = 0;
      mergedTokens.push(tokens[i]);
    }
  }
  text = buffer.join('');
  if (text) {
    mergedTokens.push(text);
  }
  buffer.length = 0;

  return mergedTokens;
};