fix(compiler-cli): emit correct css string escape sequences (#22776)

Works around an issue with TypeScript 2.6 and 2.7 that causes
the tranformer emit to emit incorrect escapes for css string
literals.

Fixes: #22774

PR Close #22776

Author: chuckjaz

packages/compiler-cli/src/transformers/node_emitter.ts

@@ -55,13 +55,28 @@ export class TypeScriptNodeEmitter {
 // NodeEmitterVisitor
 type RecordedNode<T extends ts.Node = ts.Node> = (T & { __recorded: any; }) | null;
 
+function escapeLiteral(value: string): string {
+  return value.replace(/(\"|\\)/g, '\\$1').replace(/(\n)|(\r)/g, function(v, n, r) {
+    return n ? '\\n' : '\\r';
+  });
+}
+
 function createLiteral(value: any) {
   if (value === null) {
     return ts.createNull();
   } else if (value === undefined) {
     return ts.createIdentifier('undefined');
   } else {
-    return ts.createLiteral(value);
+    const result = ts.createLiteral(value);
+    if (ts.isStringLiteral(result) && result.text.indexOf('\\') >= 0) {
+      // Hack to avoid problems cause indirectly by:
+      //    https://github.com/Microsoft/TypeScript/issues/20192
+      // This avoids the string escaping normally performed for a string relying on that
+      // TypeScript just emits the text raw for a numeric literal.
+      (result as any).kind = ts.SyntaxKind.NumericLiteral;
+      result.text = `"${escapeLiteral(result.text)}"`;
+    }
+    return result;
   }
 }
 

packages/compiler-cli/test/transformers/node_emitter_spec.ts

@@ -176,6 +176,14 @@ describe('TypeScriptNodeEmitter', () => {
                      ]).toStmt())
                .replace(/\s+/gm, ''))
         .toEqual(`({someKey:1,a:"a","b":"b","*":"star"});`);
+
+    // Regressions #22774
+    expect(emitStmt(o.literal('\\0025BC').toStmt())).toEqual('"\\\\0025BC";');
+    expect(emitStmt(o.literal('"some value"').toStmt())).toEqual('"\\"some value\\"";');
+    expect(emitStmt(o.literal('"some \\0025BC value"').toStmt()))
+        .toEqual('"\\"some \\\\0025BC value\\"";');
+    expect(emitStmt(o.literal('\n \\0025BC \n ').toStmt())).toEqual('"\\n \\\\0025BC \\n ";');
+    expect(emitStmt(o.literal('\r \\0025BC \r ').toStmt())).toEqual('"\\r \\\\0025BC \\r ";');
   });
 
   it('should support blank literals', () => {