Class TcbForOfOp

packages/compiler/src/typecheck/ops/for_block.ts:22–69

 * Executing this operation returns nothing.
 */
export class TcbForOfOp extends TcbOp {
  constructor(
    private tcb: Context,
    private scope: Scope,
    private block: ForLoopBlock,
  ) {
    super();
  }

  override get optional() {
    return false;
  }

  override execute(): null {
    const loopScope = this.scope.createChildScope(
      this.scope,
      this.block,
      this.tcb.env.config.checkControlFlowBodies ? this.block.children : [],
      null,
    );
    const initializerId = loopScope.resolve(this.block.item);
    const initializer = new TcbExpr(`const ${initializerId.print()}`);
    initializer.addParseSpanInfo(this.block.item.keySpan);

    // It's common to have a for loop over a nullable value (e.g. produced by the `async` pipe).
    // Add a non-null expression to allow such values to be assigned.
    const expression = new TcbExpr(
      `${tcbExpression(this.block.expression, this.tcb, this.scope).print()}!`,
    );

    let statements: TcbExpr[];

    if (this.block.trackBy === null) {
      statements = loopScope.render();
    } else {
      const trackTranslator = new TcbForLoopTrackTranslator(this.tcb, loopScope, this.block);
      const trackExpression = trackTranslator.translate(this.block.trackBy);
      statements = [...loopScope.render(), trackExpression];
    }

    this.scope.addStatement(
      new TcbExpr(
        `for (${initializer.print()} of ${expression.print()}) {\n${getStatementsBlock(statements)} }`,
      ),
    );
    return null;
  }
}

export class TcbForLoopTrackTranslator extends TcbExpressionTranslator {
  private allowedVariables: Set<Variable>;