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[cmv4] Implement Tab key heuristics for multiple selections #7153

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Mar 11, 2014
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[cmv4] Implement Tab key heuristics for multiple selections #7153

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f843967
Add unit tests for single-select Tab behavior. Change behavior when s…
Mar 8, 2014
c37e6cb
Implement heuristics for Tab key when multiple selections are active
Mar 11, 2014
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166 changes: 116 additions & 50 deletions src/editor/Editor.js
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Original file line number Diff line number Diff line change
Expand Up @@ -375,65 +375,131 @@ define(function (require, exports, module) {

/**
* @private
* Handle Tab key press.
* @param {!CodeMirror} instance CodeMirror instance.
* Helper function for `_handleTabKey()` (case 2) - see comment in that function.
* @param {Array.<{start:{line:number, ch:number}, end:{line:number, ch:number}, reversed:boolean, primary:boolean}>} selections
* The selections to indent.
*/
Editor.prototype._handleTabKey = function () {
// Tab key handling is done as follows:
// 1. If the selection is before any text and the indentation is to the left of
// the proper indentation then indent it to the proper place. Otherwise,
// add another tab. In either case, move the insertion point to the
// beginning of the text.
// 2. If the selection is multi-line, indent all the lines.
// 3. If the selection is after the first non-space character, and is an
// insertion point, insert a tab character or the appropriate number
// of spaces to pad to the nearest tab boundary.
Editor.prototype._addIndentAtEachSelection = function (selections) {
var instance = this._codeMirror,
from = this.getCursorPos(false, "start"),
to = this.getCursorPos(false, "end"),
line = instance.getLine(from.line),
indentAuto = false,
insertTab = false;
usingTabs = instance.getOption("indentWithTabs"),
indentUnit = instance.getOption("indentUnit"),
edits = [];

if (from.line === to.line) {
if (line.search(/\S/) > to.ch || to.ch === 0) {
indentAuto = true;
}
}

if (indentAuto) {
var currentLength = line.length;
CodeMirror.commands.indentAuto(instance);

// If the amount of whitespace and the cursor position didn't change, we must have
// already been at the correct indentation level as far as CM is concerned, so insert
// another tab.
if (instance.getLine(from.line).length === currentLength) {
var newFrom = this.getCursorPos(false, "start"),
newTo = this.getCursorPos(false, "end");
if (newFrom.line === from.line && newFrom.ch === from.ch &&
newTo.line === to.line && newTo.ch === to.ch) {
insertTab = true;
to.ch = 0;
_.each(selections, function (sel) {
var indentStr = "", i, numSpaces;
if (usingTabs) {
indentStr = "\t";
} else {
numSpaces = indentUnit - (sel.start.ch % indentUnit);
for (i = 0; i < numSpaces; i++) {
indentStr += " ";
}
}
} else if (instance.somethingSelected() && from.line !== to.line) {
CodeMirror.commands.indentMore(instance);
edits.push({edit: {text: indentStr, start: sel.start}});
});

this.document.doMultipleEdits(edits);
};

/**
* @private
* Helper function for `_handleTabKey()` (case 3) - see comment in that function.
* @param {Array.<{start:{line:number, ch:number}, end:{line:number, ch:number}, reversed:boolean, primary:boolean}>} selections
* The selections to indent.
*/
Editor.prototype._autoIndentEachSelection = function (selections) {
// Capture all the line lengths, so we can tell if anything changed.
// Note that this function should only be called if all selections are within a single line.
var instance = this._codeMirror,
lineLengths = {};
_.each(selections, function (sel) {
lineLengths[sel.start.line] = instance.getLine(sel.start.line).length;
});

// First, try to do a smart indent on all selections.
CodeMirror.commands.indentAuto(instance);

// If there were no code or selection changes, then indent each selection one more indent.
var changed = false,
newSelections = this.getSelections();
if (newSelections.length === selections.length) {
_.each(selections, function (sel, index) {
var newSel = newSelections[index];
if (CodeMirror.cmpPos(sel.start, newSel.start) !== 0 ||
CodeMirror.cmpPos(sel.end, newSel.end) !== 0 ||
instance.getLine(sel.start.line).length !== lineLengths[sel.start.line]) {
changed = true;
// Bail - we don't need to look any further once we've found a change.
return false;
}
});
} else {
insertTab = true;
changed = true;
}

if (insertTab) {
if (instance.getOption("indentWithTabs")) {
CodeMirror.commands.insertTab(instance);
} else {
var i, ins = "", numSpaces = instance.getOption("indentUnit");
numSpaces -= from.ch % numSpaces;
for (i = 0; i < numSpaces; i++) {
ins += " ";
}
instance.replaceSelection(ins, "end");
if (!changed) {
CodeMirror.commands.indentMore(instance);
}
};

/**
* @private
* Handle Tab key press.
* @param {!CodeMirror} instance CodeMirror instance.
*/
Editor.prototype._handleTabKey = function () {
// Tab key handling is done as follows:
// 1. If any of the selections are multiline, just add one indent level to the
// beginning of all lines that intersect any selection.
// 2. Otherwise, if any of the selections is a cursor or single-line range that
// ends at or after the first non-whitespace character in a line:
// - if indentation is set to tabs, just insert a hard tab before each selection.
// - if indentation is set to spaces, insert the appropriate number of spaces before
// each selection to get to its next soft tab stop.
// 3. Otherwise (all selections are cursors or single-line, and are in the whitespace
// before their respective lines), try to autoindent each line based on the mode.
// If none of the cursors moved and no space was added, then add one indent level
// to the beginning of all lines.

// Note that in case 2, we do the "dumb" insertion even if the cursor is immediately
// before the first non-whitespace character in a line. It might seem more convenient
// to do autoindent in that case. However, the problem is if that line is already
// indented past its "proper" location. In that case, we don't want Tab to
// *outdent* the line. If we had more control over the autoindent algorithm or
// implemented it ourselves, we could handle that case separately.

var instance = this._codeMirror,
selectionType = "indentAuto",
selections = this.getSelections();

_.each(selections, function (sel) {
if (sel.start.line !== sel.end.line) {
// Case 1 - we found a multiline selection. We can bail as soon as we find one of these.
selectionType = "indentAtBeginning";
return false;
} else if (sel.end.ch >= instance.getLine(sel.end.line).search(/\S/)) {
// Case 2 - we found a selection that ends at or after the first non-whitespace
// character on the line. We need to keep looking in case we find a later multiline
// selection though.
selectionType = "indentAtSelection";
}
});

switch (selectionType) {
case "indentAtBeginning":
// Case 1
CodeMirror.commands.indentMore(instance);
break;

case "indentAtSelection":
// Case 2
this._addIndentAtEachSelection(selections);
break;

case "indentAuto":
// Case 3
this._autoIndentEachSelection(selections);
break;
}
};

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