Function readInput

GUI/codemirror/lib/codemirror.js:2223–2300

(cm)

  // seen text (can be empty), which is stored in prevInput (we must
  // not reset the textarea when typing, because that breaks IME).
  function readInput(cm) {
    var input = cm.display.input, prevInput = cm.display.prevInput, doc = cm.doc;
    // Since this is called a *lot*, try to bail out as cheaply as
    // possible when it is clear that nothing happened. hasSelection
    // will be the case when there is a lot of text in the textarea,
    // in which case reading its value would be expensive.
    if (!cm.state.focused || (hasSelection(input) && !prevInput) || isReadOnly(cm) || cm.options.disableInput)
      return false;
    // See paste handler for more on the fakedLastChar kludge
    if (cm.state.pasteIncoming && cm.state.fakedLastChar) {
      input.value = input.value.substring(0, input.value.length - 1);
      cm.state.fakedLastChar = false;
    }
    var text = input.value;
    // If nothing changed, bail.
    if (text == prevInput && !cm.somethingSelected()) return false;
    // Work around nonsensical selection resetting in IE9/10
    if (ie && !ie_upto8 && cm.display.inputHasSelection === text) {
      resetInput(cm);
      return false;
    }

    var withOp = !cm.curOp;
    if (withOp) startOperation(cm);
    cm.display.shift = false;

    // Find the part of the input that is actually new
    var same = 0, l = Math.min(prevInput.length, text.length);
    while (same < l && prevInput.charCodeAt(same) == text.charCodeAt(same)) ++same;
    var inserted = text.slice(same), textLines = splitLines(inserted);

    // When pasing N lines into N selections, insert one line per selection
    var multiPaste = cm.state.pasteIncoming && textLines.length > 1 && doc.sel.ranges.length == textLines.length;

    // Normal behavior is to insert the new text into every selection
    for (var i = doc.sel.ranges.length - 1; i >= 0; i--) {
      var range = doc.sel.ranges[i];
      var from = range.from(), to = range.to();
      // Handle deletion
      if (same < prevInput.length)
        from = Pos(from.line, from.ch - (prevInput.length - same));
      // Handle overwrite
      else if (cm.state.overwrite && range.empty() && !cm.state.pasteIncoming)
        to = Pos(to.line, Math.min(getLine(doc, to.line).text.length, to.ch + lst(textLines).length));
      var updateInput = cm.curOp.updateInput;
      var changeEvent = {from: from, to: to, text: multiPaste ? [textLines[i]] : textLines,
                         origin: cm.state.pasteIncoming ? "paste" : cm.state.cutIncoming ? "cut" : "+input"};
      makeChange(cm.doc, changeEvent);
      signalLater(cm, "inputRead", cm, changeEvent);
      // When an 'electric' character is inserted, immediately trigger a reindent
      if (inserted && !cm.state.pasteIncoming && cm.options.electricChars &&
          cm.options.smartIndent && range.head.ch < 100 &&
          (!i || doc.sel.ranges[i - 1].head.line != range.head.line)) {
        var mode = cm.getModeAt(range.head);
        if (mode.electricChars) {
          for (var j = 0; j < mode.electricChars.length; j++)
            if (inserted.indexOf(mode.electricChars.charAt(j)) > -1) {
              indentLine(cm, range.head.line, "smart");