refactor(compiler): support o.BinaryExpression for assignments

Previously the compiler output AST did not support using
`o.BinaryExpression` for assignments (as TypeScript does). Instead
`o.WriteVarExpr` is defined, which only allows writing to string named
variables.

packages/compiler-cli/src/ngtsc/translator/src/api/ast_factory.ts

@@ -245,7 +245,7 @@ export type UnaryOperator = '+'|'-'|'!';
  * The binary operators supported by the `AstFactory`.
  */
 export type BinaryOperator =
-    '&&'|'>'|'>='|'&'|'/'|'=='|'==='|'<'|'<='|'-'|'%'|'*'|'!='|'!=='|'||'|'+'|'??';
+    '&&'|'>'|'>='|'&'|'/'|'='|'=='|'==='|'<'|'<='|'-'|'%'|'*'|'!='|'!=='|'||'|'+'|'??';
 
 /**
  * The original location of the start or end of a node created by the `AstFactory`.

packages/compiler-cli/src/ngtsc/translator/src/translator.ts

@@ -18,6 +18,7 @@ const UNARY_OPERATORS = new Map<o.UnaryOperator, UnaryOperator>([
 
 const BINARY_OPERATORS = new Map<o.BinaryOperator, BinaryOperator>([
   [o.BinaryOperator.And, '&&'],
+  [o.BinaryOperator.Assign, '='],
   [o.BinaryOperator.Bigger, '>'],
   [o.BinaryOperator.BiggerEquals, '>='],
   [o.BinaryOperator.BitwiseAnd, '&'],

packages/compiler-cli/src/ngtsc/translator/src/typescript_ast_factory.ts

@@ -31,6 +31,7 @@ const UNARY_OPERATORS: Record<UnaryOperator, ts.PrefixUnaryOperator> = {
 };
 
 const BINARY_OPERATORS: Record<BinaryOperator, ts.BinaryOperator> = {
+  '=': ts.SyntaxKind.EqualsToken,
   '&&': ts.SyntaxKind.AmpersandAmpersandToken,
   '>': ts.SyntaxKind.GreaterThanToken,
   '>=': ts.SyntaxKind.GreaterThanEqualsToken,

packages/compiler/src/output/abstract_emitter.ts

@@ -436,6 +436,9 @@ export abstract class AbstractEmitterVisitor implements o.StatementVisitor, o.Ex
       case o.BinaryOperator.NullishCoalesce:
         opStr = '??';
         break;
+      case o.BinaryOperator.Assign:
+        opStr = '=';
+        break;
       default:
         throw new Error(`Unknown operator ${ast.operator}`);
     }

packages/compiler/src/output/output_ast.ts

@@ -114,6 +114,7 @@ export enum UnaryOperator {
 }
 
 export enum BinaryOperator {
+  Assign,
   Equals,
   NotEquals,
   Identical,