build: fix multi-line selectors in dgeni (#4336)

* Fixes multi-line selectors not being detected properly (https://github.com/angular/material2/blob/master/src/lib/button/button.ts#L185-L185)
* Template strings not being detected properly (https://github.com/angular/material2/blob/master/src/lib/input/input-container.ts#L103-L103)
* No longer repeats RegExp logic multiple times. More generic function.

Author: devversion

tools/dgeni/processors/categorizer.js

@@ -46,7 +46,7 @@ module.exports = function categorizer() {
     // Categorize the current visited classDoc into its Angular type.
     if (isDirective(classDoc)) {
       classDoc.isDirective = true;
-      classDoc.directiveExportAs = getDirectiveExportAs(classDoc);
+      classDoc.directiveExportAs = getMetadataProperty(classDoc, 'exportAs');
       classDoc.directiveSelectors =  getDirectiveSelectors(classDoc);
     } else if (isService(classDoc)) {
       classDoc.isService = true;
@@ -186,26 +186,25 @@ function getDirectiveOutputAlias(doc) {
 }
 
 function getDirectiveSelectors(classDoc) {
-  let metadata = classDoc.decorators
-    .find(d => d.name === 'Component' || d.name === 'Directive').arguments[0];
-
-  let selectorMatches = /selector\s*:\s*(?:"|')([^']*?)(?:"|')/g.exec(metadata);
-  selectorMatches = selectorMatches && selectorMatches[1];
+  const directiveSelectors = getMetadataProperty(classDoc, 'selector');
 
-  return selectorMatches ? selectorMatches.split(/\s*,\s*/)
-    .filter(s => s !== '' && !s.includes('mat') && !SELECTOR_BLACKLIST.has(s))
-    : selectorMatches;
+  if (directiveSelectors) {
+    // Filter blacklisted selectors and remove line-breaks in resolved selectors.
+    return directiveSelectors.replace(/[\r\n]/g, '').split(/\s*,\s*/)
+      .filter(s => s !== '' && !s.includes('mat') && !SELECTOR_BLACKLIST.has(s));
+  }
 }
 
-function getDirectiveExportAs(doc) {
-  let metadata = doc.decorators
-      .find(d => d.name === 'Component' || d.name === 'Directive').arguments[0];
+function getMetadataProperty(doc, property) {
+  const metadata = doc.decorators
+    .find(d => d.name === 'Component' || d.name === 'Directive').arguments[0];
 
-  // Use a Regex to determine the exportAs metadata because we can't parse the JSON due to
-  // environment variables inside of the JSON.
-  let exportMatches = /exportAs\s*:\s*(?:"|')(\w+)(?:"|')/g.exec(metadata);
+  // Use a Regex to determine the given metadata property. This is necessary, because we can't
+  // parse the JSON due to environment variables inside of the JSON (e.g module.id)
+  let matches = new RegExp(`${property}s*:\\s*(?:"|'|\`)((?:.|\\n|\\r)+?)(?:"|'|\`)`)
+    .exec(metadata);
 
-  return exportMatches && exportMatches[1];
+  return matches && matches[1].trim();
 }
 
 function hasMemberDecorator(doc, decoratorName) {