// Utility function that allows modes to be combined. The mode given

// as the base argument takes care of most of the normal mode

// functionality, but a second (typically simple) mode is used, which

// can override the style of text. Both modes get to parse all of the

// text, but when both assign a non-null style to a piece of code, the

// overlay wins, unless the combine argument was true, in which case

// the styles are combined.



// overlayParser is the old, deprecated name

CodeMirror.overlayMode = CodeMirror.overlayParser = function(base, overlay, combine) {

  return {

    startState: function() {

      return {

        base: CodeMirror.startState(base),

        overlay: CodeMirror.startState(overlay),

        basePos: 0, baseCur: null,

        overlayPos: 0, overlayCur: null

      };

    },

    copyState: function(state) {

      return {

        base: CodeMirror.copyState(base, state.base),

        overlay: CodeMirror.copyState(overlay, state.overlay),

        basePos: state.basePos, baseCur: null,

        overlayPos: state.overlayPos, overlayCur: null

      };

    },



    token: function(stream, state) {

      if (stream.start == state.basePos) {

        state.baseCur = base.token(stream, state.base);

        state.basePos = stream.pos;

      }

      if (stream.start == state.overlayPos) {

        stream.pos = stream.start;

        state.overlayCur = overlay.token(stream, state.overlay);

        state.overlayPos = stream.pos;

      }

      stream.pos = Math.min(state.basePos, state.overlayPos);

      if (stream.eol()) state.basePos = state.overlayPos = 0;



      if (state.overlayCur == null) return state.baseCur;

      if (state.baseCur != null && combine) return state.baseCur + " " + state.overlayCur;

      else return state.overlayCur;

    },

    

    indent: base.indent && function(state, textAfter) {

      return base.indent(state.base, textAfter);

    },

    electricChars: base.electricChars,



    innerMode: function(state) { return {state: state.base, mode: base}; },

    

    blankLine: function(state) {

      if (base.blankLine) base.blankLine(state.base);

      if (overlay.blankLine) overlay.blankLine(state.overlay);

    }

  };

};

