Class TcbSwitchOp

packages/compiler/src/typecheck/ops/switch_block.ts:21–147

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

  override get optional() {
    return false;
  }

  override execute(): null {
    const switchExpression = tcbExpression(this.block.expression, this.tcb, this.scope);
    const clauses = this.block.groups.flatMap<TcbExpr>((current) => {
      const checkBody = this.tcb.env.config.checkControlFlowBodies;
      const clauseScope = this.scope.createChildScope(
        this.scope,
        null,
        checkBody ? current.children : [],
        checkBody ? this.generateGuard(current, switchExpression) : null,
      );

      const statements = [...clauseScope.render(), new TcbExpr('break')];

      return current.cases.map((switchCase, index) => {
        const statementsStr = getStatementsBlock(
          index === current.cases.length - 1 ? statements : [],
          true /* singleLine */,
        );

        const source =
          switchCase.expression === null
            ? `default: ${statementsStr}`
            : `case ${tcbExpression(switchCase.expression, this.tcb, this.scope).print()}: ${statementsStr}`;

        return new TcbExpr(source);
      });
    });

    if (this.block.exhaustiveCheck) {
      let translateExpression = this.block.expression;
      if (this.block.exhaustiveCheck.expression) {
        translateExpression = this.block.exhaustiveCheck.expression;
      }

      const switchValue = tcbExpression(translateExpression, this.tcb, this.scope);
      const exhaustiveId = this.tcb.allocateId();

      clauses.push(
        new TcbExpr(`default: const tcbExhaustive${exhaustiveId}: never = ${switchValue.print()};`),
      );
    }

    this.scope.addStatement(
      new TcbExpr(
        `switch (${switchExpression.print()}) { ${clauses.map((c) => c.print()).join('\n')} }`,