src/Linkifier.ts

   1 /**
   2  * @license MIT
   3  */
   4
   5 export type LinkHandler = (uri: string) => void;
   6
   7 type LinkMatcher = {id: number, regex: RegExp, matchIndex?: number, handler: LinkHandler};
   8
   9 const protocolClause = '(https?:\\/\\/)';
  10 const domainCharacterSet = '[\\da-z\\.-]+';
  11 const negatedDomainCharacterSet = '[^\\da-z\\.-]+';
  12 const domainBodyClause = '(' + domainCharacterSet + ')';
  13 const tldClause = '([a-z\\.]{2,6})';
  14 const ipClause = '((\\d{1,3}\\.){3}\\d{1,3})';
  15 const localHostClause = '(localhost)';
  16 const portClause = '(:\\d{1,5})';
  17 const hostClause = '((' + domainBodyClause + '\\.' + tldClause + ')|' + ipClause + '|' + localHostClause + ')' + portClause + '?';
  18 const pathClause = '(\\/[\\/\\w\\.-]*)*';
  19 const queryStringClause = '(\\?[\\w\\[\\]\\(\\)\\/\\?\\!#@$&\'*+,:;\\=]*)?';
  20 const negatedPathCharacterSet = '[^\\/\\w\\.-]+';
  21 const bodyClause = hostClause + pathClause + queryStringClause;
  22 const start = '(?:^|' + negatedDomainCharacterSet + ')(';
  23 const end = ')($|' + negatedPathCharacterSet + ')';
  24 const strictUrlRegex = new RegExp(start + protocolClause + bodyClause + end);
  25
  26 /**
  27  * The ID of the built in http(s) link matcher.
  28  */
  29 const HYPERTEXT_LINK_MATCHER_ID = 0;
  30
  31 /**
  32  * The time to wait after a row is changed before it is linkified. This prevents
  33  * the costly operation of searching every row multiple times, pntentially a
  34  * huge aount of times.
  35  */
  36 const TIME_BEFORE_LINKIFY = 200;
  37
  38 /**
  39  * The Linkifier applies links to rows shortly after they have been refreshed.
  40  */
  41 export class Linkifier {
  42   private _rows: HTMLElement[];
  43   private _rowTimeoutIds: number[];
  44   private _linkMatchers: LinkMatcher[];
  45   private _nextLinkMatcherId = HYPERTEXT_LINK_MATCHER_ID;
  46
  47   constructor(rows: HTMLElement[]) {
  48     this._rows = rows;
  49     this._rowTimeoutIds = [];
  50     this._linkMatchers = [];
  51     this.registerLinkMatcher(strictUrlRegex, null, 1);
  52   }
  53
  54   /**
  55    * Queues a row for linkification.
  56    * @param {number} rowIndex The index of the row to linkify.
  57    */
  58   public linkifyRow(rowIndex: number): void {
  59     const timeoutId = this._rowTimeoutIds[rowIndex];
  60     if (timeoutId) {
  61       clearTimeout(timeoutId);
  62     }
  63     this._rowTimeoutIds[rowIndex] = setTimeout(this._linkifyRow.bind(this, rowIndex), TIME_BEFORE_LINKIFY);
  64   }
  65
  66   /**
  67    * Attaches a handler for hypertext links, overriding default <a> behavior
  68    * for standard http(s) links.
  69    * @param {LinkHandler} handler The handler to use, this can be cleared with
  70    * null.
  71    */
  72   public attachHypertextLinkHandler(handler: LinkHandler): void {
  73     this._linkMatchers[HYPERTEXT_LINK_MATCHER_ID].handler = handler;
  74   }
  75
  76   /**
  77    * Registers a link matcher, allowing custom link patterns to be matched and
  78    * handled.
  79    * @param {RegExp} regex The regular expression to search for, specifically
  80    * this searches the textContent of the rows. You will want to use \s to match
  81    * a space ' ' character for example.
  82    * @param {LinkHandler} handler The callback when the link is called.
  83    * @param {number} matchIndex The index of the link from the regex.match(text)
  84    * call. This defaults to 0 (for regular expressions without capture groups).
  85    * @return {number} The ID of the new matcher, this can be used to deregister.
  86    */
  87   public registerLinkMatcher(regex: RegExp, handler: LinkHandler, matchIndex?: number): number {
  88     if (this._nextLinkMatcherId !== HYPERTEXT_LINK_MATCHER_ID && !handler) {
  89       throw new Error('handler cannot be falsy');
  90     }
  91     const matcher: LinkMatcher = {
  92       id: this._nextLinkMatcherId++,
  93       regex,
  94       handler,
  95       matchIndex
  96     };
  97     this._linkMatchers.push(matcher);
  98     return matcher.id;
  99   }
 100
 101   /**
 102    * Deregisters a link matcher if it has been registered.
 103    * @param {number} matcherId The link matcher's ID (returned after register)
 104    * @return {boolean} Whether a link matcher was found and deregistered.
 105    */
 106   public deregisterLinkMatcher(matcherId: number): boolean {
 107     // ID 0 is the hypertext link matcher which cannot be deregistered
 108     for (let i = 1; i < this._linkMatchers.length; i++) {
 109       if (this._linkMatchers[i].id === matcherId) {
 110         this._linkMatchers.splice(i, 1);
 111         return true;
 112       }
 113     }
 114     return false;
 115   }
 116
 117   /**
 118    * Linkifies a row.
 119    * @param {number} rowIndex The index of the row to linkify.
 120    */
 121   private _linkifyRow(rowIndex: number): void {
 122     const row = this._rows[rowIndex];
 123     if (!row) {
 124       return;
 125     }
 126     const text = row.textContent;
 127     for (let i = 0; i < this._linkMatchers.length; i++) {
 128       const matcher = this._linkMatchers[i];
 129       const uri = this._findLinkMatch(text, matcher.regex, matcher.matchIndex);
 130       if (uri) {
 131         this._doLinkifyRow(rowIndex, uri, matcher.handler);
 132         // Only allow a single LinkMatcher to trigger on any given row.
 133         return;
 134       }
 135     }
 136   }
 137
 138   /**
 139    * Linkifies a row given a specific handler.
 140    * @param {number} rowIndex The index of the row to linkify.
 141    * @param {string} uri The uri that has been found.
 142    * @param {handler} handler The handler to trigger when the link is triggered.
 143    */
 144   private _doLinkifyRow(rowIndex: number, uri: string, handler?: LinkHandler): void {
 145     // Iterate over nodes as we want to consider text nodes
 146     const nodes = this._rows[rowIndex].childNodes;
 147     for (let i = 0; i < nodes.length; i++) {
 148       const node = nodes[i];
 149       const searchIndex = node.textContent.indexOf(uri);
 150       if (searchIndex >= 0) {
 151         const linkElement = this._createAnchorElement(uri, handler);
 152         if (node.textContent.length === uri.length) {
 153           // Matches entire string
 154           if (node.nodeType === Node.TEXT_NODE) {
 155             this._replaceNode(node, linkElement);
 156           } else {
 157             const element = (<HTMLElement>node);
 158             if (element.nodeName === 'A') {
 159               // This row has already been linkified
 160               return;
 161             }
 162             element.innerHTML = '';
 163             element.appendChild(linkElement);
 164           }
 165         } else {
 166           // Matches part of string
 167           this._replaceNodeSubstringWithNode(node, linkElement, uri, searchIndex);
 168         }
 169       }
 170     }
 171   }
 172
 173   /**
 174    * Finds a link match in a piece of text.
 175    * @param {string} text The text to search.
 176    * @param {number} matchIndex The regex match index of the link.
 177    * @return {string} The matching URI or null if not found.
 178    */
 179   private _findLinkMatch(text: string, regex: RegExp, matchIndex?: number): string {
 180     const match = text.match(regex);
 181     if (!match || match.length === 0) {
 182       return null;
 183     }
 184     return match[typeof matchIndex !== 'number' ? 0 : matchIndex];
 185   }
 186
 187   /**
 188    * Creates a link anchor element.
 189    * @param {string} uri The uri of the link.
 190    * @return {HTMLAnchorElement} The link.
 191    */
 192   private _createAnchorElement(uri: string, handler: LinkHandler): HTMLAnchorElement {
 193     const element = document.createElement('a');
 194     element.textContent = uri;
 195     if (handler) {
 196       element.addEventListener('click', () => handler(uri));
 197     } else {
 198       element.href = uri;
 199       // Force link on another tab so work is not lost
 200       element.target = '_blank';
 201     }
 202     return element;
 203   }
 204
 205   /**
 206    * Replace a node with 1 or more other nodes.
 207    * @param {Node} oldNode The node to replace.
 208    * @param {Node[]} newNodes The new nodes to insert in order.
 209    */
 210   private _replaceNode(oldNode: Node, ...newNodes: Node[]): void {
 211     const parent = oldNode.parentNode;
 212     for (let i = 0; i < newNodes.length; i++) {
 213       parent.insertBefore(newNodes[i], oldNode);
 214     }
 215     parent.removeChild(oldNode);
 216   }
 217
 218   /**
 219    * Replace a substring within a node with a new node.
 220    * @param {Node} targetNode The target node; either a text node or a <span>
 221    * containing a single text node.
 222    * @param {Node} newNode The new node to insert.
 223    * @param {string} substring The substring to replace.
 224    * @param {number} substringIndex The index of the substring within the string.
 225    */
 226   private _replaceNodeSubstringWithNode(targetNode: Node, newNode: Node, substring: string, substringIndex: number): void {
 227     let node = targetNode;
 228     if (node.nodeType !== Node.TEXT_NODE) {
 229       node = node.childNodes[0];
 230     }
 231
 232     // The targetNode will be either a text node or a <span>. The text node
 233     // (targetNode or its only-child) needs to be replaced with newNode plus new
 234     // text nodes potentially on either side.
 235     if (node.childNodes.length === 0 && node.nodeType !== Node.TEXT_NODE) {
 236       throw new Error('targetNode must be a text node or only contain a single text node');
 237     }
 238
 239     const fullText = node.textContent;
 240
 241     if (substringIndex === 0) {
 242       // Replace with <newNode><textnode>
 243       const rightText = fullText.substring(substring.length);
 244       const rightTextNode = document.createTextNode(rightText);
 245       this._replaceNode(node, newNode, rightTextNode);
 246     } else if (substringIndex === targetNode.textContent.length - substring.length) {
 247       // Replace with <textnode><newNode>
 248       const leftText = fullText.substring(0, substringIndex);
 249       const leftTextNode = document.createTextNode(leftText);
 250       this._replaceNode(node, leftTextNode, newNode);
 251     } else {
 252       // Replace with <textnode><newNode><textnode>
 253       const leftText = fullText.substring(0, substringIndex);
 254       const leftTextNode = document.createTextNode(leftText);
 255       const rightText = fullText.substring(substringIndex + substring.length);
 256       const rightTextNode = document.createTextNode(rightText);
 257       this._replaceNode(node, leftTextNode, newNode, rightTextNode);
 258     }
 259   }
 260 }