/**
* Storage and control for undo information within a CodeMirror
* editor. 'Why on earth is such a complicated mess required for
* that?', I hear you ask. The goal, in implementing this, was to make
* the complexity of storing and reverting undo information depend
* only on the size of the edited or restored content, not on the size
* of the whole document. This makes it necessary to use a kind of
* 'diff' system, which, when applied to a DOM tree, causes some
* complexity and hackery.
*
* In short, the editor 'touches' BR elements as it parses them, and
* the History stores these. When nothing is touched in commitDelay
* milliseconds, the changes are committed: It goes over all touched
* nodes, throws out the ones that did not change since last commit or
* are no longer in the document, and assembles the rest into zero or
* more 'chains' -- arrays of adjacent lines. Links back to these
* chains are added to the BR nodes, while the chain that previously
* spanned these nodes is added to the undo history. Undoing a change
* means taking such a chain off the undo history, restoring its
* content (text is saved per line) and linking it back into the
* document.
*/
// A history object needs to know about the DOM container holding the
// document, the maximum amount of undo levels it should store, the
// delay (of no input) after which it commits a set of changes, and,
// unfortunately, the 'parent' window -- a window that is not in
// designMode, and on which setTimeout works in every browser.
function History(container, maxDepth, commitDelay, editor) {
this.container = container;
this.maxDepth = maxDepth;
this.commitDelay = commitDelay;
this.editor = editor;
this.parent = editor.parent;
// This line object represents the initial, empty editor.
var initial = {text: "", from: null, to: null};
// As the borders between lines are represented by BR elements, the
// start of the first line and the end of the last one are
// represented by null. Since you can not store any properties
// (links to line objects) in null, these properties are used in
// those cases.
this.first = initial;
this.last = initial;
// Similarly, a 'historyTouched' property is added to the BR in
// front of lines that have already been touched, and 'firstTouched'
// is used for the first line.
this.firstTouched = false;
// History is the set of committed changes, touched is the set of
// nodes touched since the last commit.
this.history = [];
this.redoHistory = [];
this.touched = [];
}
History.prototype = {
// Schedule a commit (if no other touches come in for commitDelay
// milliseconds).
scheduleCommit: function () {
var self = this;
this.parent.clearTimeout(this.commitTimeout);
this.commitTimeout = this.parent.setTimeout(function () {
self.tryCommit();
}, this.commitDelay);
},
// Mark a node as touched. Null is a valid argument.
touch: function (node) {
this.setTouched(node);
this.scheduleCommit();
},
// Undo the last change.
undo: function () {
// Make sure pending changes have been committed.
this.commit();
if (this.history.length) {
// Take the top diff from the history, apply it, and store its
// shadow in the redo history.
var item = this.history.pop();
this.redoHistory.push(this.updateTo(item, "applyChain"));
this.notifyEnvironment();
return this.chainNode(item);
}
},
// Redo the last undone change.
redo: function () {
this.commit();
if (this.redoHistory.length) {
// The inverse of undo, basically.
var item = this.redoHistory.pop();
this.addUndoLevel(this.updateTo(item, "applyChain"));
this.notifyEnvironment();
return this.chainNode(item);
}
},
clear: function () {
this.history = [];
this.redoHistory = [];
},
// Ask for the size of the un/redo histories.
historySize: function () {
return {undo: this.history.length, redo: this.redoHistory.length};
},
// Push a changeset into the document.
push: function (from, to, lines) {
var chain = [];
for (var i = 0; i < lines.length; i++) {
var end = (i == lines.length - 1) ? to : this.container.ownerDocument.createElement("BR");
chain.push({from: from, to: end, text: cleanText(lines[i])});
from = end;
}
this.pushChains([chain], from == null && to == null);
this.notifyEnvironment();
},
pushChains: function (chains, doNotHighlight) {
this.commit(doNotHighlight);
this.addUndoLevel(this.updateTo(chains, "applyChain"));
this.redoHistory = [];
},
// Retrieve a DOM node from a chain (for scrolling to it after undo/redo).
chainNode: function (chains) {
for (var i = 0; i < chains.length; i++) {
var start = chains[i][0], node = start && (start.from || start.to);
if (node) return node;
}
},
// Clear the undo history, make the current document the start
// position.
reset: function () {
this.history = [];
this.redoHistory = [];
},
textAfter: function (br) {
return this.after(br).text;
},
nodeAfter: function (br) {
return this.after(br).to;
},
nodeBefore: function (br) {
return this.before(br).from;
},
// Commit unless there are pending dirty nodes.
tryCommit: function () {
if (!window.History) return; // Stop when frame has been unloaded
if (this.editor.highlightDirty()) this.commit(true);
else this.scheduleCommit();
},
// Check whether the touched nodes hold any changes, if so, commit
// them.
commit: function (doNotHighlight) {
this.parent.clearTimeout(this.commitTimeout);
// Make sure there are no pending dirty nodes.
if (!doNotHighlight) this.editor.highlightDirty(true);
// Build set of chains.
var chains = this.touchedChains(), self = this;
if (chains.length) {
this.addUndoLevel(this.updateTo(chains, "linkChain"));
this.redoHistory = [];
this.notifyEnvironment();
}
},
// [ end of public interface ]
// Update the document with a given set of chains, return its
// shadow. updateFunc should be "applyChain" or "linkChain". In the
// second case, the chains are taken to correspond the the current
// document, and only the state of the line data is updated. In the
// first case, the content of the chains is also pushed iinto the
// document.
updateTo: function (chains, updateFunc) {
var shadows = [], dirty = [];
for (var i = 0; i < chains.length; i++) {
shadows.push(this.shadowChain(chains[i]));
dirty.push(this[updateFunc](chains[i]));
}
if (updateFunc == "applyChain")
this.notifyDirty(dirty);
return shadows;
},
// Notify the editor that some nodes have changed.
notifyDirty: function (nodes) {
forEach(nodes, method(this.editor, "addDirtyNode"))
this.editor.scheduleHighlight();
},
notifyEnvironment: function () {
// Used by the line-wrapping line-numbering code.
if (window.frameElement && window.frameElement.CodeMirror.updateNumbers)
window.frameElement.CodeMirror.updateNumbers();
if (this.onChange) this.onChange();
},
// Link a chain into the DOM nodes (or the first/last links for null
// nodes).
linkChain: function (chain) {
for (var i = 0; i < chain.length; i++) {
var line = chain[i];
if (line.from) line.from.historyAfter = line;
else this.first = line;
if (line.to) line.to.historyBefore = line;
else this.last = line;
}
},
// Get the line object after/before a given node.
after: function (node) {
return node ? node.historyAfter : this.first;
},
before: function (node) {
return node ? node.historyBefore : this.last;
},
// Mark a node as touched if it has not already been marked.
setTouched: function (node) {
if (node) {
if (!node.historyTouched) {
this.touched.push(node);
node.historyTouched = true;
}
}
else {
this.firstTouched = true;
}
},
// Store a new set of undo info, throw away info if there is more of
// it than allowed.
addUndoLevel: function (diffs) {
this.history.push(diffs);
if (this.history.length > this.maxDepth)
this.history.shift();
},
// Build chains from a set of touched nodes.
touchedChains: function () {
var self = this;
// The temp system is a crummy hack to speed up determining
// whether a (currently touched) node has a line object associated
// with it. nullTemp is used to store the object for the first
// line, other nodes get it stored in their historyTemp property.
var nullTemp = null;
function temp(node) {
return node ? node.historyTemp : nullTemp;
}
function setTemp(node, line) {
if (node) node.historyTemp = line;
else nullTemp = line;
}
function buildLine(node) {
var text = [];
for (var cur = node ? node.nextSibling : self.container.firstChild;
cur && !isBR(cur); cur = cur.nextSibling)
if (cur.currentText) text.push(cur.currentText);
return {from: node, to: cur, text: cleanText(text.join(""))};
}
// Filter out unchanged lines and nodes that are no longer in the
// document. Build up line objects for remaining nodes.
var lines = [];
if (self.firstTouched) self.touched.push(null);
forEach(self.touched, function (node) {
if (node && node.parentNode != self.container) return;
if (node) node.historyTouched = false;
else self.firstTouched = false;
var line = buildLine(node), shadow = self.after(node);
if (!shadow || shadow.text != line.text || shadow.to != line.to) {
lines.push(line);
setTemp(node, line);
}
});
// Get the BR element after/before the given node.
function nextBR(node, dir) {
var link = dir + "Sibling", search = node[link];
while (search && !isBR(search))
search = search[link];
return search;
}
// Assemble line objects into chains by scanning the DOM tree
// around them.
var chains = [];
self.touched = [];
forEach(lines, function (line) {
// Note that this makes the loop skip line objects that have
// been pulled into chains by lines before them.
if (!temp(line.from)) return;
var chain = [], curNode = line.from, safe = true;
// Put any line objects (referred to by temp info) before this
// one on the front of the array.
while (true) {
var curLine = temp(curNode);
if (!curLine) {
if (safe) break;
else curLine = buildLine(curNode);
}
chain.unshift(curLine);
setTemp(curNode, null);
if (!curNode) break;
safe = self.after(curNode);
curNode = nextBR(curNode, "previous");
}
curNode = line.to;
safe = self.before(line.from);
// Add lines after this one at end of array.
while (true) {
if (!curNode) break;
var curLine = temp(curNode);
if (!curLine) {
if (safe) break;
else curLine = buildLine(curNode);
}
chain.push(curLine);
setTemp(curNode, null);
safe = self.before(curNode);
curNode = nextBR(curNode, "next");
}
chains.push(chain);
});
return chains;
},
// Find the 'shadow' of a given chain by following the links in the
// DOM nodes at its start and end.
shadowChain: function (chain) {
var shadows = [], next = this.after(chain[0].from), end = chain[chain.length - 1].to;
while (true) {
shadows.push(next);
var nextNode = next.to;
if (!nextNode || nextNode == end)
break;
else
next = nextNode.historyAfter || this.before(end);
// (The this.before(end) is a hack -- FF sometimes removes
// properties from BR nodes, in which case the best we can hope
// for is to not break.)
}
return shadows;
},
// Update the DOM tree to contain the lines specified in a given
// chain, link this chain into the DOM nodes.
applyChain: function (chain) {
// Some attempt is made to prevent the cursor from jumping
// randomly when an undo or redo happens. It still behaves a bit
// strange sometimes.
var cursor = select.cursorPos(this.container, false), self = this;
// Remove all nodes in the DOM tree between from and to (null for
// start/end of container).
function removeRange(from, to) {
var pos = from ? from.nextSibling : self.container.firstChild;
while (pos != to) {
var temp = pos.nextSibling;
removeElement(pos);
pos = temp;
}
}
var start = chain[0].from, end = chain[chain.length - 1].to;
// Clear the space where this change has to be made.
removeRange(start, end);
// Insert the content specified by the chain into the DOM tree.
for (var i = 0; i < chain.length; i++) {
var line = chain[i];
// The start and end of the space are already correct, but BR
// tags inside it have to be put back.
if (i > 0)
self.container.insertBefore(line.from, end);
// Add the text.
var node = makePartSpan(fixSpaces(line.text), this.container.ownerDocument);
self.container.insertBefore(node, end);
// See if the cursor was on this line. Put it back, adjusting
// for changed line length, if it was.
if (cursor && cursor.node == line.from) {
var cursordiff = 0;
var prev = this.after(line.from);
if (prev && i == chain.length - 1) {
// Only adjust if the cursor is after the unchanged part of
// the line.
for (var match = 0; match < cursor.offset &&
line.text.charAt(match) == prev.text.charAt(match); match++);
if (cursor.offset > match)
cursordiff = line.text.length - prev.text.length;
}
select.setCursorPos(this.container, {node: line.from, offset: Math.max(0, cursor.offset + cursordiff)});
}
// Cursor was in removed line, this is last new line.
else if (cursor && (i == chain.length - 1) && cursor.node && cursor.node.parentNode != this.container) {
select.setCursorPos(this.container, {node: line.from, offset: line.text.length});
}
}
// Anchor the chain in the DOM tree.
this.linkChain(chain);
return start;
}
};
|
Download
