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// Copyright (C) 2016 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the 'License');
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an 'AS IS' BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
(function(window) {
'use strict';
// Prevent redefinition.
if (window.GrAnnotation) { return; }
// TODO(wyatta): refactor this to be <MARK> rather than <HL>.
const ANNOTATION_TAG = 'HL';
// Astral code point as per https://mathiasbynens.be/notes/javascript-unicode
const REGEX_ASTRAL_SYMBOL = /[\uD800-\uDBFF][\uDC00-\uDFFF]/;
const GrAnnotation = {
/**
* The DOM API textContent.length calculation is broken when the text
* contains Unicode. See https://mathiasbynens.be/notes/javascript-unicode .
* @param {Text} A text node.
* @return {Number} The length of the text.
*/
getLength(node) {
return this.getStringLength(node.textContent);
},
getStringLength(str) {
return str.replace(REGEX_ASTRAL_SYMBOL, '_').length;
},
/**
* Surrounds the element's text at specified range in an ANNOTATION_TAG
* element. If the element has child elements, the range is split and
* applied as deeply as possible.
*/
annotateElement(parent, offset, length, cssClass) {
const nodes = [].slice.apply(parent.childNodes);
let nodeLength;
let subLength;
for (const node of nodes) {
nodeLength = this.getLength(node);
// If the current node is completely before the offset.
if (nodeLength <= offset) {
offset -= nodeLength;
continue;
}
// Sublength is the annotation length for the current node.
subLength = Math.min(length, nodeLength - offset);
if (node instanceof Text) {
this._annotateText(node, offset, subLength, cssClass);
} else if (node instanceof HTMLElement) {
this.annotateElement(node, offset, subLength, cssClass);
}
// If there is still more to annotate, then shift the indices, otherwise
// work is done, so break the loop.
if (subLength < length) {
length -= subLength;
offset = 0;
} else {
break;
}
}
},
/**
* Wraps node in annotation tag with cssClass, replacing the node in DOM.
*
* @return {!Element} Wrapped node.
*/
wrapInHighlight(node, cssClass) {
let hl;
if (node.tagName === ANNOTATION_TAG) {
hl = node;
hl.classList.add(cssClass);
} else {
hl = document.createElement(ANNOTATION_TAG);
hl.className = cssClass;
Polymer.dom(node.parentElement).replaceChild(hl, node);
Polymer.dom(hl).appendChild(node);
}
return hl;
},
/**
* Splits Text Node and wraps it in hl with cssClass.
* Wraps trailing part after split, tailing one if opt_firstPart is true.
*
* @param {!Node} node
* @param {number} offset
* @param {string} cssClass
* @param {boolean=} opt_firstPart
*/
splitAndWrapInHighlight(node, offset, cssClass, opt_firstPart) {
if (this.getLength(node) === offset || offset === 0) {
return this.wrapInHighlight(node, cssClass);
} else {
if (opt_firstPart) {
this.splitNode(node, offset);
// Node points to first part of the Text, second one is sibling.
} else {
node = this.splitNode(node, offset);
}
return this.wrapInHighlight(node, cssClass);
}
},
/**
* Splits Node at offset.
* If Node is Element, it's cloned and the node at offset is split too.
*
* @param {!Node} node
* @param {number} offset
* @return {!Node} Trailing Node.
*/
splitNode(element, offset) {
if (element instanceof Text) {
return this.splitTextNode(element, offset);
}
const tail = element.cloneNode(false);
element.parentElement.insertBefore(tail, element.nextSibling);
// Skip nodes before offset.
let node = element.firstChild;
while (node &&
this.getLength(node) <= offset ||
this.getLength(node) === 0) {
offset -= this.getLength(node);
node = node.nextSibling;
}
if (this.getLength(node) > offset) {
tail.appendChild(this.splitNode(node, offset));
}
while (node.nextSibling) {
tail.appendChild(node.nextSibling);
}
return tail;
},
/**
* Node.prototype.splitText Unicode-valid alternative.
*
* DOM Api for splitText() is broken for Unicode:
* https://mathiasbynens.be/notes/javascript-unicode
*
* @param {!Text} node
* @param {number} offset
* @return {!Text} Trailing Text Node.
*/
splitTextNode(node, offset) {
if (node.textContent.match(REGEX_ASTRAL_SYMBOL)) {
// TODO (viktard): Polyfill Array.from for IE10.
const head = Array.from(node.textContent);
const tail = head.splice(offset);
const parent = node.parentNode;
// Split the content of the original node.
node.textContent = head.join('');
const tailNode = document.createTextNode(tail.join(''));
if (parent) {
parent.insertBefore(tailNode, node.nextSibling);
}
return tailNode;
} else {
return node.splitText(offset);
}
},
_annotateText(node, offset, length, cssClass) {
const nodeLength = this.getLength(node);
// There are four cases:
// 1) Entire node is highlighted.
// 2) Highlight is at the start.
// 3) Highlight is at the end.
// 4) Highlight is in the middle.
if (offset === 0 && nodeLength === length) {
// Case 1.
this.wrapInHighlight(node, cssClass);
} else if (offset === 0) {
// Case 2.
this.splitAndWrapInHighlight(node, length, cssClass, true);
} else if (offset + length === nodeLength) {
// Case 3
this.splitAndWrapInHighlight(node, offset, cssClass, false);
} else {
// Case 4
this.splitAndWrapInHighlight(this.splitTextNode(node, offset), length,
cssClass, true);
}
},
};
window.GrAnnotation = GrAnnotation;
})(window);