carbon/lib/customModes/kotlin.js

const CodeMirror = require('codemirror');

CodeMirror.defineMode('kotlin', function(config, parserConfig) {
  function words(str) {
    var obj = {},
      words = str.split(' ');
    for (var i = 0; i < words.length; ++i) obj[words[i]] = true;
    return obj;
  }

  var multiLineStrings = parserConfig.multiLineStrings;

  var keywords = words(
    'package continue return object while break class data trait throw super ' +
      'when type this else This try val var fun for is in if do as true false null get set ' +
      'import where by get set abstract enum open annotation override private public internal ' +
      'protected catch out vararg inline finally final ref const'
  );
  var blockKeywords = words('catch class do else finally for if where try while enum');
  var atoms = words('null true false this');
  var builtins = words(
    'Int Double Float Long Short Byte IntArray ShortArray ByteArray String Boolean List Set ' +
      'Map MutableList MutableSet print println shl shr ushr and or xor inv '
  );

  var curPunc;

  function tokenBase(stream, state) {
    var ch = stream.next();

    if (ch == '"' || ch == "'") {
      return startString(ch, stream, state);
    }

    // Wildcard import w/o trailing semicolon (import smth.*)
    if (ch == '.' && stream.eat('*')) {
      return 'word';
    }

    if (/[\[\]{}\(\),;\:\.]/.test(ch)) {
      curPunc = ch;
      return null;
    }

    if (/\d/.test(ch)) {
      if (stream.eat(/eE/)) {
        stream.eat(/\+\-/);
        stream.eatWhile(/\d/);
      }

      return 'number';
    }

    if (ch == '/') {
      if (stream.eat('*')) {
        state.tokenize.push(tokenComment);
        return tokenComment(stream, state);
      }

      if (stream.eat('/')) {
        stream.skipToEnd();
        return 'comment';
      }

      if (expectExpression(state.lastToken)) {
        return startString(ch, stream, state);
      }
    }

    // Commented
    if (ch == '-' && stream.eat('>')) {
      curPunc = '->';
      return null;
    }

    if (/[\-+*&%=<>!?|\/~]/.test(ch)) {
      stream.eatWhile(/[\-+*&%=<>|~]/);
      return 'operator';
    }

    stream.eatWhile(/[\w\$_]/);

    var cur = stream.current();

    if (atoms.propertyIsEnumerable(cur)) {
      return 'atom';
    }

    if (keywords.propertyIsEnumerable(cur)) {
      if (blockKeywords.propertyIsEnumerable(cur)) curPunc = 'newstatement';
      return 'keyword';
    }

    if (builtins.propertyIsEnumerable(cur)) {
      return 'builtin';
    }

    return 'word';
  }

  tokenBase.isBase = true;

  function startString(quote, stream, state) {
    var tripleQuoted = false;
    if (quote != '/' && stream.eat(quote)) {
      if (stream.eat(quote)) tripleQuoted = true;
      else return 'string';
    }

    function t(stream, state) {
      var escaped = false,
        next,
        end = !tripleQuoted;

      while ((next = stream.next()) != null) {
        if (next == quote && !escaped) {
          if (!tripleQuoted) {
            break;
          }

          if (stream.match(quote + quote)) {
            end = true;
            break;
          }
        }

        if (quote == '"' && next == '$' && !escaped && stream.eat('{')) {
          state.tokenize.push(tokenBaseUntilBrace());
          return 'string';
        }

        if (next == '$' && !escaped && !stream.eat(' ')) {
          state.tokenize.push(tokenBaseUntilSpace());
          return 'string';
        }
        escaped = !escaped && next == '\\';
      }

      if (multiLineStrings) state.tokenize.push(t);

      if (end) state.tokenize.pop();

      return 'string';
    }

    state.tokenize.push(t);
    return t(stream, state);
  }

  function tokenBaseUntilBrace() {
    var depth = 1;

    function t(stream, state) {
      if (stream.peek() == '}') {
        depth--;
        if (depth == 0) {
          state.tokenize.pop();
          return state.tokenize[state.tokenize.length - 1](stream, state);
        }
      } else if (stream.peek() == '{') {
        depth++;
      }

      return tokenBase(stream, state);
    }

    t.isBase = true;
    return t;
  }

  function tokenBaseUntilSpace() {
    function t(stream, state) {
      if (stream.eat(/[\w]/)) {
        var isWord = stream.eatWhile(/[\w]/);
        if (isWord) {
          state.tokenize.pop();
          return 'word';
        }
      }
      state.tokenize.pop();
      return 'string';
    }

    t.isBase = true;
    return t;
  }

  function tokenComment(stream, state) {
    var maybeEnd = false,
      ch;
    while ((ch = stream.next())) {
      if (ch == '/' && maybeEnd) {
        state.tokenize.pop();
        break;
      }

      maybeEnd = ch == '*';
    }

    return 'comment';
  }

  function expectExpression(last) {
    return (
      !last ||
      last == 'operator' ||
      last == '->' ||
      /[\.\[\{\(,;:]/.test(last) ||
      last == 'newstatement' ||
      last == 'keyword' ||
      last == 'proplabel'
    );
  }

  function Context(indented, column, type, align, prev) {
    this.indented = indented;
    this.column = column;
    this.type = type;
    this.align = align;
    this.prev = prev;
  }

  function pushContext(state, col, type) {
    return (state.context = new Context(state.indented, col, type, null, state.context));
  }

  function popContext(state) {
    var t = state.context.type;
    if (t == ')' || t == ']' || t == '}') state.indented = state.context.indented;
    return (state.context = state.context.prev);
  }

  // Interface

  return {
    startState: function(basecolumn) {
      return {
        tokenize: [tokenBase],
        context: new Context((basecolumn || 0) - config.indentUnit, 0, 'top', false),
        indented: 0,
        startOfLine: true,
        lastToken: null
      };
    },

    token: function(stream, state) {
      var ctx = state.context;
      if (stream.sol()) {
        if (ctx.align == null) ctx.align = false;
        state.indented = stream.indentation();
        state.startOfLine = true;
        // Automatic semicolon insertion
        if (ctx.type == 'statement' && !expectExpression(state.lastToken)) {
          popContext(state);
          ctx = state.context;
        }
      }
      if (stream.eatSpace()) return null;
      curPunc = null;
      var style = state.tokenize[state.tokenize.length - 1](stream, state);
      if (style == 'comment') return style;
      if (ctx.align == null) ctx.align = true;
      if ((curPunc == ';' || curPunc == ':') && ctx.type == 'statement') popContext(state);
      else if (curPunc == '->' && ctx.type == 'statement' && ctx.prev.type == '}') {
        // Handle indentation for {x -> \n ... }
        popContext(state);
        state.context.align = false;
      } else if (curPunc == '{') pushContext(state, stream.column(), '}');
      else if (curPunc == '[') pushContext(state, stream.column(), ']');
      else if (curPunc == '(') pushContext(state, stream.column(), ')');
      else if (curPunc == '}') {
        while (ctx.type == 'statement') ctx = popContext(state);
        if (ctx.type == '}') ctx = popContext(state);
        while (ctx.type == 'statement') ctx = popContext(state);
      } else if (curPunc == ctx.type) popContext(state);
      else if (
        ctx.type == '}' ||
        ctx.type == 'top' ||
        (ctx.type == 'statement' && curPunc == 'newstatement')
      )
        pushContext(state, stream.column(), 'statement');
      state.startOfLine = false;
      state.lastToken = curPunc || style;
      return style;
    },

    indent: function(state, textAfter) {
      if (!state.tokenize[state.tokenize.length - 1].isBase) return 0;
      var firstChar = textAfter && textAfter.charAt(0),
        ctx = state.context;
      if (ctx.type == 'statement' && !expectExpression(state.lastToken)) ctx = ctx.prev;
      var closing = firstChar == ctx.type;
      if (ctx.type == 'statement') {
        return ctx.indented + (firstChar == '{' ? 0 : config.indentUnit);
      } else if (ctx.align) return ctx.column + (closing ? 0 : 1);
      else return ctx.indented + (closing ? 0 : config.indentUnit);
    },

    closeBrackets: {
      triples: '\'"'
    },
    electricChars: '{}'
  };
});

CodeMirror.defineMIME('text/x-kotlin', 'kotlin');