mediawiki-extensions-Visual.../modules/ve/dm/ve.dm.Transaction.js
Trevor Parscal 6f8b0965f2 Remove range.normalize (not needed), use range.isCollapsed more often
The normalize method doesn't need to be explicitly called anymore because there's not any code that changes the properties of a range directly anymore.

A good way to prove it's not needed anymore is to move the normalization logic to the constructor and then add "console.log(this.from <= this.to );" to the normalize method - you will find that it's never actually doing anything at all because the range was normalized by the constructor.

ve.Range
* Moved normalization logic to constructor
* Removed calls to normalize method
* Removed normalize method
* Simplified documentation for flip method
* Whitespace fixes

ve.Document, ve.dm.Transaction, ve.dm.Surface, ve.dm.Document, ve.ce.Surface
* Removed calls to range.normalize
* Switched to using range.isCollapsed instead of comparing properties directly

Change-Id: I80bfd06f88579c34dce2083c2b70d63ab92f1275
2013-01-16 15:38:07 -08:00

775 lines
26 KiB
JavaScript

/*!
* VisualEditor DataModel Transaction class.
*
* @copyright 2011-2012 VisualEditor Team and others; see AUTHORS.txt
* @license The MIT License (MIT); see LICENSE.txt
*/
/**
* DataModel transaction.
*
* @class
* @constructor
*/
ve.dm.Transaction = function VeDmTransaction() {
this.operations = [];
this.lengthDifference = 0;
this.applied = false;
this.changeMarkers = {};
};
/* Static Methods */
/**
* Generate a transaction that inserts data at an offset.
*
* @static
* @method
* @param {ve.dm.Document} doc Document to create transaction for
* @param {number} offset Offset to insert at
* @param {Array} data Data to insert
* @returns {ve.dm.Transaction} Transcation that inserts data
*/
ve.dm.Transaction.newFromInsertion = function ( doc, offset, insertion ) {
var tx = new ve.dm.Transaction(),
data = doc.getData();
// Fix up the insertion
insertion = doc.fixupInsertion( insertion, offset );
// Retain up to insertion point, if needed
tx.pushRetain( offset );
// Insert data
tx.pushReplace( [], insertion );
// Retain to end of document, if needed (for completeness)
tx.pushRetain( data.length - offset );
return tx;
};
/**
* Generate a transaction that removes data from a range.
*
* There are three possible results from a removal:
*
* - Remove content only
* - Occurs when the range starts and ends on elements of different type, depth or ancestry
* - Remove entire elements and their content
* - Occurs when the range spans across an entire element
* - Merge two elements by removing the end of one and the beginning of another
* - Occurs when the range starts and ends on elements of similar type, depth and ancestry
*
* This function uses the following logic to decide what to actually remove:
*
* 1. Elements are only removed if range being removed covers the entire element
* 2. Elements can only be merged if {@link ve.dm.Node#canBeMergedWith} returns true
* 3. Merges take place at the highest common ancestor
*
* @method
* @param {ve.dm.Document} doc Document to create transaction for
* @param {ve.Range} range Range of data to remove
* @returns {ve.dm.Transaction} Transcation that removes data
* @throws {Error} Invalid range
*/
ve.dm.Transaction.newFromRemoval = function ( doc, range ) {
var i, selection, first, last, nodeStart, nodeEnd,
offset = 0,
removeStart = null,
removeEnd = null,
tx = new ve.dm.Transaction(),
data = doc.getData();
// Validate range
if ( range.isCollapsed() ) {
// Empty range, nothing to remove, retain up to the end of the document (for completeness)
tx.pushRetain( data.length );
return tx;
}
// Select nodes and validate selection
selection = doc.selectNodes( range, 'covered' );
if ( selection.length === 0 ) {
// Empty selection? Something is wrong!
throw new Error( 'Invalid range, cannot remove from ' + range.start + ' to ' + range.end );
}
first = selection[0];
last = selection[selection.length - 1];
// If the first and last node are mergeable, merge them
if ( first.node.canBeMergedWith( last.node ) ) {
if ( !first.range && !last.range ) {
// First and last node are both completely covered, remove them
removeStart = first.nodeOuterRange.start;
removeEnd = last.nodeOuterRange.end;
} else {
// Either the first node or the last node is partially covered, so remove
// the selected content
removeStart = ( first.range || first.nodeRange ).start;
removeEnd = ( last.range || last.nodeRange ).end;
}
tx.pushRetain( removeStart );
tx.pushReplace( data.slice( removeStart, removeEnd ), [] );
tx.pushRetain( data.length - removeEnd );
// All done
return tx;
}
// The selection wasn't mergeable, so remove nodes that are completely covered, and strip
// nodes that aren't
for ( i = 0; i < selection.length; i++ ) {
if ( !selection[i].range ) {
// Entire node is covered, remove it
nodeStart = selection[i].nodeOuterRange.start;
nodeEnd = selection[i].nodeOuterRange.end;
} else {
// Part of the node is covered, remove that range
nodeStart = selection[i].range.start;
nodeEnd = selection[i].range.end;
}
// Merge contiguous removals. Only apply a removal when a gap appears, or at the
// end of the loop
if ( removeEnd === null ) {
// First removal
removeStart = nodeStart;
removeEnd = nodeEnd;
} else if ( removeEnd === nodeStart ) {
// Merge this removal into the previous one
removeEnd = nodeEnd;
} else {
// There is a gap between the previous removal and this one
// Push the previous removal first
tx.pushRetain( removeStart - offset );
tx.pushReplace( data.slice( removeStart, removeEnd ), [] );
offset = removeEnd;
// Now start this removal
removeStart = nodeStart;
removeEnd = nodeEnd;
}
}
// Apply the last removal, if any
if ( removeEnd !== null ) {
tx.pushRetain( removeStart - offset );
tx.pushReplace( data.slice( removeStart, removeEnd ), [] );
offset = removeEnd;
}
// Retain up to the end of the document
tx.pushRetain( data.length - offset );
return tx;
};
/**
* Generate a transaction that changes an attribute.
*
* @static
* @method
* @param {ve.dm.Document} doc Document to create transaction for
* @param {number} offset Offset of element
* @param {string} key Attribute name
* @param {Mixed} value New value, or undefined to remove the attribute
* @returns {ve.dm.Transaction} Transcation that changes an element
* @throws {Error} Cannot set attributes to non-element data
* @throws {Error} Cannot set attributes on closing element
*/
ve.dm.Transaction.newFromAttributeChange = function ( doc, offset, key, value ) {
var tx = new ve.dm.Transaction(),
data = doc.getData();
// Verify element exists at offset
if ( data[offset].type === undefined ) {
throw new Error( 'Cannot set attributes to non-element data' );
}
// Verify element is not a closing
if ( data[offset].type.charAt( 0 ) === '/' ) {
throw new Error( 'Cannot set attributes on closing element' );
}
// Retain up to element
tx.pushRetain( offset );
// Change attribute
tx.pushReplaceElementAttribute(
key, 'attributes' in data[offset] ? data[offset].attributes[key] : undefined, value
);
// Retain to end of document
tx.pushRetain( data.length - offset );
return tx;
};
/**
* Generate a transaction that annotates content.
*
* @static
* @method
* @param {ve.dm.Document} doc Document to create transaction for
* @param {ve.Range} range Range to annotate
* @param {string} method Annotation mode
* - `set`: Adds annotation to all content in range
* - `clear`: Removes instances of annotation from content in range
* @param {Object} annotation Annotation to set or clear
* @returns {ve.dm.Transaction} Transaction that annotates content
*/
ve.dm.Transaction.newFromAnnotation = function ( doc, range, method, annotation ) {
var covered, type,
tx = new ve.dm.Transaction(),
data = doc.getData(),
i = range.start,
span = i,
on = false;
// Iterate over all data in range, annotating where appropriate
while ( i < range.end ) {
type = data[i].type;
if ( type && type.charAt( 0 ) === '/' ) {
type = type.substr( 1 );
}
if ( data[i].type !== undefined && !ve.dm.nodeFactory.isNodeContent( type ) ) {
// Structural element opening or closing
if ( on ) {
tx.pushRetain( span );
tx.pushStopAnnotating( method, annotation );
span = 0;
on = false;
}
} else if ( data[i].type === undefined || data[i].type.charAt( 0 ) !== '/' ) {
// Character or content element opening
covered = doc.offsetContainsAnnotation( i, annotation );
if ( ( covered && method === 'set' ) || ( !covered && method === 'clear' ) ) {
// Skip annotated content
if ( on ) {
tx.pushRetain( span );
tx.pushStopAnnotating( method, annotation );
span = 0;
on = false;
}
} else {
// Cover non-annotated content
if ( !on ) {
tx.pushRetain( span );
tx.pushStartAnnotating( method, annotation );
span = 0;
on = true;
}
}
} // otherwise it's a content closing, skip those
span++;
i++;
}
tx.pushRetain( span );
if ( on ) {
tx.pushStopAnnotating( method, annotation );
}
tx.pushRetain( data.length - range.end );
return tx;
};
/**
* Generate a transaction that converts elements that can contain content.
*
* @static
* @method
* @param {ve.dm.Document} doc Document to create transaction for
* @param {ve.Range} range Range to convert
* @param {string} type Symbolic name of element type to convert to
* @param {Object} attr Attributes to initialize element with
* @returns {ve.dm.Transaction} Transaction that converts content branches
*/
ve.dm.Transaction.newFromContentBranchConversion = function ( doc, range, type, attr ) {
var i, selected, branch, branchOuterRange,
tx = new ve.dm.Transaction(),
data = doc.getData(),
selection = doc.selectNodes( range, 'leaves' ),
opening = { 'type': type },
closing = { 'type': '/' + type },
previousBranch,
previousBranchOuterRange;
// Add attributes to opening if needed
if ( ve.isPlainObject( attr ) ) {
opening.attributes = attr;
} else {
attr = {};
}
// Replace the wrappings of each content branch in the range
for ( i = 0; i < selection.length; i++ ) {
selected = selection[i];
if ( selected.node.isContent() ) {
branch = selected.node.getParent();
// Skip branches that are already of the target type and have identical attributes
if ( branch.getType() === type && ve.compareObjects( branch.getAttributes(), attr ) ) {
continue;
}
branchOuterRange = branch.getOuterRange();
// Don't convert the same branch twice
if ( branch === previousBranch ) {
continue;
}
// Retain up to this branch, considering where the previous one left off
tx.pushRetain(
branchOuterRange.start - ( previousBranch ? previousBranchOuterRange.end : 0 )
);
// Replace the opening
tx.pushReplace( [data[branchOuterRange.start]], [ve.copyObject( opening )] );
// Retain the contents
tx.pushRetain( branch.getLength() );
// Replace the closing
tx.pushReplace( [data[branchOuterRange.end - 1]], [ve.copyObject( closing )] );
// Remember this branch and its range for next time
previousBranch = branch;
previousBranchOuterRange = branchOuterRange;
}
}
// Retain until the end
tx.pushRetain(
data.length - ( previousBranch ? previousBranchOuterRange.end : 0 )
);
return tx;
};
/**
* Generate a transaction that wraps, unwraps or replaces structure.
*
* The unwrap parameters are checked against the actual model data, and
* an exception is thrown if the type fields don't match. This means you
* can omit attributes from the unwrap parameters, those are automatically
* picked up from the model data instead.
*
* NOTE: This function currently does not fix invalid parent/child relationships, so it will
* happily convert paragraphs to listItems without wrapping them in a list if that's what you
* ask it to do. We'll probably fix this later but for now the caller is responsible for giving
* valid instructions.
*
* Changing a paragraph to a header:
* Before: [ {'type': 'paragraph'}, 'a', 'b', 'c', {'type': '/paragraph'} ]
* newFromWrap( new ve.Range( 1, 4 ), [ {'type': 'paragraph'} ], [ {'type': 'heading', 'level': 1 } ] );
* After: [ {'type': 'heading', 'level': 1 }, 'a', 'b', 'c', {'type': '/heading'} ]
*
* Changing a set of paragraphs to a list:
* Before: [ {'type': 'paragraph'}, 'a', {'type': '/paragraph'}, {'type':'paragraph'}, 'b', {'type':'/paragraph'} ]
* newFromWrap( new ve.Range( 0, 6 ), [], [ {'type': 'list' } ], [], [ {'type': 'listItem', 'attributes': {'styles': ['bullet']}} ] );
* After: [ {'type': 'list'}, {'type': 'listItem', 'attributes': {'styles': ['bullet']}}, {'type':'paragraph'} 'a',
* {'type': '/paragraph'}, {'type': '/listItem'}, {'type': 'listItem', 'attributes': {'styles': ['bullet']}},
* {'type': 'paragraph'}, 'b', {'type': '/paragraph'}, {'type': '/listItem'}, {'type': '/list'} ]
*
* @param {ve.dm.Document} doc Document to generate a transaction for
* @param {ve.Range} range Range to wrap/unwrap/replace around
* @param {Array} unwrapOuter Oopening elements to unwrap. These must be immediately *outside* the range.
* @param {Array} wrapOuter Opening elements to wrap around the range.
* @param {Array} unwrapEach Opening elements to unwrap from each top-level element in the range.
* @param {Array} wrapEach Opening elements to wrap around each top-level element in the range.
* @returns {ve.dm.Transaction}
*/
ve.dm.Transaction.newFromWrap = function ( doc, range, unwrapOuter, wrapOuter, unwrapEach, wrapEach ) {
var i, j, unwrapOuterData, startOffset, unwrapEachData, closingUnwrapEach, closingWrapEach,
tx = new ve.dm.Transaction(),
depth = 0;
// Function to generate arrays of closing elements in reverse order
function closingArray( openings ) {
var closings = [], i, len = openings.length;
for ( i = 0; i < len; i++ ) {
closings[closings.length] = { 'type': '/' + openings[len - i - 1].type };
}
return closings;
}
closingUnwrapEach = closingArray( unwrapEach );
closingWrapEach = closingArray( wrapEach );
// TODO: check for and fix nesting validity like fixupInsertion does
if ( range.start > unwrapOuter.length ) {
// Retain up to the first thing we're unwrapping
// The outer unwrapping takes place *outside*
// the range, so compensate for that
tx.pushRetain( range.start - unwrapOuter.length );
} else if ( range.start < unwrapOuter.length ) {
throw new Error( 'unwrapOuter is longer than the data preceding the range' );
}
// Replace the opening elements for the outer unwrap&wrap
if ( wrapOuter.length > 0 || unwrapOuter.length > 0 ) {
// Verify that wrapOuter matches the data at this position
unwrapOuterData = doc.data.slice( range.start - unwrapOuter.length, range.start );
for ( i = 0; i < unwrapOuterData.length; i++ ) {
if ( unwrapOuterData[i].type !== unwrapOuter[i].type ) {
throw new Error( 'Element in unwrapOuter does not match: expected ' +
unwrapOuter[i].type + ' but found ' + unwrapOuterData[i].type );
}
}
// Instead of putting in unwrapOuter as given, put it in the
// way it appears in the mode,l so we pick up any attributes
tx.pushReplace( unwrapOuterData, ve.copyArray( wrapOuter ) );
}
if ( wrapEach.length > 0 || unwrapEach.length > 0 ) {
// Visit each top-level child and wrap/unwrap it
// TODO figure out if we should use the tree/node functions here
// rather than iterating over offsets, it may or may not be faster
for ( i = range.start; i < range.end; i++ ) {
if ( doc.data[i].type !== undefined ) {
// This is a structural offset
if ( doc.data[i].type.charAt( 0 ) !== '/' ) {
// This is an opening element
if ( depth === 0 ) {
// We are at the start of a top-level element
// Replace the opening elements
// Verify that unwrapEach matches the data at this position
unwrapEachData = doc.data.slice( i, i + unwrapEach.length );
for ( j = 0; j < unwrapEachData.length; j++ ) {
if ( unwrapEachData[j].type !== unwrapEach[j].type ) {
throw new Error( 'Element in unwrapEach does not match: expected ' +
unwrapEach[j].type + ' but found ' +
unwrapEachData[j].type );
}
}
// Instead of putting in unwrapEach as given, put it in the
// way it appears in the model, so we pick up any attributes
tx.pushReplace( ve.copyArray( unwrapEachData ), ve.copyArray( wrapEach ) );
// Store this offset for later
startOffset = i;
}
depth++;
} else {
// This is a closing element
depth--;
if ( depth === 0 ) {
// We are at the end of a top-level element
// Retain the contents of what we're wrapping
tx.pushRetain( i - startOffset + 1 - unwrapEach.length*2 );
// Replace the closing elements
tx.pushReplace( ve.copyArray( closingUnwrapEach ), ve.copyArray( closingWrapEach ) );
}
}
}
}
} else {
// There is no wrapEach/unwrapEach to be done, just retain
// up to the end of the range
tx.pushRetain( range.end - range.start );
}
if ( wrapOuter.length > 0 || unwrapOuter.length > 0 ) {
tx.pushReplace( closingArray( unwrapOuter ), closingArray( wrapOuter ) );
}
// Retain up to the end of the document
if ( range.end < doc.data.length ) {
tx.pushRetain( doc.data.length - range.end - unwrapOuter.length );
}
return tx;
};
/* Methods */
/**
* Check if the transaction would make any actual changes if processed.
*
* There may be more sophisticated checks that can be done, like looking for things being replaced
* with identical content, but such transactions probably should not be created in the first place.
*
* @method
* @returns {boolean} Transaction is no-op
*/
ve.dm.Transaction.prototype.isNoOp = function () {
return (
this.operations.length === 0 ||
( this.operations.length === 1 && this.operations[0].type === 'retain' )
);
};
/**
* Get all operations.
*
* @method
* @returns {Object[]} List of operations
*/
ve.dm.Transaction.prototype.getOperations = function () {
return this.operations;
};
/**
* Check if the transaction has any operations with a certain type.
*
* @method
* @returns {boolean} Has operations of a given type
*/
ve.dm.Transaction.prototype.hasOperationWithType = function ( type ) {
var i, len;
for ( i = 0, len = this.operations.length; i < len; i++ ) {
if ( this.operations[i].type === type ) {
return true;
}
}
return false;
};
/**
* Check if the transaction has any content data operations, such as insertion or deletion.
*
* @method
* @returns {boolean} Has content data operations
*/
ve.dm.Transaction.prototype.hasContentDataOperations = function () {
return this.hasOperationWithType( 'replace' );
};
/**
* Check if the transaction has any element attribute operations.
*
* @method
* @returns {boolean} Has element attribute operations
*/
ve.dm.Transaction.prototype.hasElementAttributeOperations = function () {
return this.hasOperationWithType( 'attribute' );
};
/**
* Check if the transaction has any annotation operations.
*
* @method
* @returns {boolean} Has annotation operations
*/
ve.dm.Transaction.prototype.hasAnnotationOperations = function () {
return this.hasOperationWithType( 'annotate' );
};
/**
* Get the difference in content length the transaction will cause if applied.
*
* @method
* @returns {number} Difference in content length
*/
ve.dm.Transaction.prototype.getLengthDifference = function () {
return this.lengthDifference;
};
/**
* Check whether the transaction has already been applied.
*
* A transaction that has been applied can be rolled back, at which point it will no longer be
* considered applied. In other words, this function returns false if the transaction can be
* committed, and true if the transaction can be rolled back.
*
* @method
* @returns {boolean}
*/
ve.dm.Transaction.prototype.hasBeenApplied = function () {
return this.applied;
};
/**
* Toggle the applied state of the transaction.
*
* Should only be called after committing or rolling back the transaction.
*
* @see ve.dm.Transaction#hasBeenApplied
*/
ve.dm.Transaction.prototype.toggleApplied = function () {
this.applied = !this.applied;
};
/**
* Translate an offset based on a transaction.
*
* This is useful when you want to anticipate what an offset will be after a transaction is
* processed.
*
* @method
* @param {number} offset Offset in the linear model before the transaction has been processed
* @returns {number} Translated offset, as it will be after processing transaction
*/
ve.dm.Transaction.prototype.translateOffset = function ( offset, reversed ) {
var i, cursor = 0, adjustment = 0, op, insertLength, removeLength;
for ( i = 0; i < this.operations.length; i++ ) {
op = this.operations[i];
if ( op.type === 'replace' ) {
insertLength = reversed ? op.remove.length : op.insert.length;
removeLength = reversed ? op.insert.length : op.remove.length;
adjustment += insertLength - removeLength;
if ( offset === cursor + removeLength ) {
// Offset points to right after the removal, translate it
return offset + adjustment;
} else if ( offset >= cursor && offset < cursor + removeLength ) {
// The offset points inside of the removal
return cursor + removeLength + adjustment;
}
cursor += removeLength;
} else if ( op.type === 'retain' ) {
if ( offset >= cursor && offset < cursor + op.length ) {
return offset + adjustment;
}
cursor += op.length;
}
}
return offset + adjustment;
};
/**
* Translate a range based on a transaction.
*
* This is useful when you want to anticipate what a selection will be after a transaction is
* processed.
*
* @method
* @see #translateOffset
* @param {ve.Range} range Range in the linear model before the transaction has been processed
* @returns {ve.Range} Translated range, as it will be after processing transaction
*/
ve.dm.Transaction.prototype.translateRange = function ( range, reversed ) {
return new ve.Range( this.translateOffset( range.from, reversed ), this.translateOffset( range.to, reversed ) );
};
/**
* Add a retain operation.
*
* @method
* @param {number} length Length of content data to retain
* @throws {Error} Cannot retain backwards.
*/
ve.dm.Transaction.prototype.pushRetain = function ( length ) {
if ( length < 0 ) {
throw new Error( 'Invalid retain length, cannot retain backwards:' + length );
}
if ( length ) {
var end = this.operations.length - 1;
if ( this.operations.length && this.operations[end].type === 'retain' ) {
this.operations[end].length += length;
} else {
this.operations.push( {
'type': 'retain',
'length': length
} );
}
}
};
/**
* Add a replace operation
*
* @method
* @param {Array} remove Data to remove
* @param {Array} insert Data to replace 'remove' with
*/
ve.dm.Transaction.prototype.pushReplace = function ( remove, insert ) {
if ( remove.length === 0 && insert.length === 0 ) {
// Don't push no-ops
return;
}
this.operations.push( {
'type': 'replace',
'remove': remove,
'insert': insert
} );
this.lengthDifference += insert.length - remove.length;
};
/**
* Add an element attribute change operation.
*
* @method
* @param {string} key Name of attribute to change
* @param {Mixed} from Value change attribute from, or undefined if not previously set
* @param {Mixed} to Value to change attribute to, or undefined to remove
*/
ve.dm.Transaction.prototype.pushReplaceElementAttribute = function ( key, from, to ) {
this.operations.push( {
'type': 'attribute',
'key': key,
'from': from,
'to': to
} );
};
/**
* Add a start annotating operation.
*
* @method
* @param {string} method Method to use, either "set" or "clear"
* @param {Object} annotation Annotation object to start setting or clearing from content data
*/
ve.dm.Transaction.prototype.pushStartAnnotating = function ( method, annotation ) {
this.operations.push( {
'type': 'annotate',
'method': method,
'bias': 'start',
'annotation': annotation
} );
};
/**
* Add a stop annotating operation.
*
* @method
* @param {string} method Method to use, either "set" or "clear"
* @param {Object} annotation Annotation object to stop setting or clearing from content data
*/
ve.dm.Transaction.prototype.pushStopAnnotating = function ( method, annotation ) {
this.operations.push( {
'type': 'annotate',
'method': method,
'bias': 'stop',
'annotation': annotation
} );
};
/**
* Get the change markers for the transaction.
*
* Change markers are added using setChangeMarker().
*
* @returns {Object} { offset: { markerType: number } }
*/
ve.dm.Transaction.prototype.getChangeMarkers = function () {
return this.changeMarkers;
};
/**
* Store a change marker to mark a change made while applying the transaction.
*
* Markers are stored in the .internal.changed property of elements in the linear model, as well as
* in the Transaction that effected the changes.
*
* The purpose of storing change markers in the linear model is so the linmod->HTML converter can
* mark what has changed relative to the HTML we originally received. For that reason, change
* markers only track what has changed relative to the original state of the document. This means
* we avoid reporting changes that cancel each other out, where possible. For instance, if an
* element marked 'created' is changed, this doesn't result in an additional change marker.
* In particular, rolling back a transaction causes all change marking done by that transaction to
* be undone. For that reason, change markers are stored in the Transaction object as well, so it's
* easy to undo a transaction's markers when rolling back.
*
* Marker types:
* - 'created': This element was newly created and did not exist in the original document
* - 'attributes': This element's attributes have changed
* - 'content': This element's content changed (content-containing elements only)
* - 'annotations': The annotations within this element changed (content-containing elements only)
* - 'rebuilt': This element and its children/contents changed in some way, no details available
*
* Change markers are numbers, which are incremented when setting a marker and decremented when
* unsetting it. This is because the same event can occur multiple times for the same element, and
* we want to be able to keep track of whether all the changes have canceled each other out.
*
* @param {number} offset Linear model offset (post-transaction) of the element to mark
* @param {string} marker Marker type
* @param {number} [increment=1] Number to add to the change marker counter
*/
ve.dm.Transaction.prototype.setChangeMarker = function ( offset, marker, increment ) {
increment = increment || 1;
if ( this.changeMarkers[offset] === undefined ) {
this.changeMarkers[offset] = {};
}
if ( this.changeMarkers[offset].created ) {
// Can't set any other markers on a 'created' element
return;
}
if ( marker === 'created' ) {
// Clear other markers prior to setting 'created'
this.changeMarkers[offset] = {};
}
if ( this.changeMarkers[offset][marker] === undefined ) {
this.changeMarkers[offset][marker] = increment;
} else {
this.changeMarkers[offset][marker] += increment;
}
};
/**
* Clear all change markers.
*/
ve.dm.Transaction.prototype.clearChangeMarkers = function () {
this.changeMarkers = {};
};