Class TcbIfBlockOp

packages/compiler/src/typecheck/ops/if_block.ts:21–137

 * Executing this operation returns nothing.
 */
export class TcbIfBlockOp extends TcbOp {
  private expressionScopes = new Map<IfBlockBranch, Scope>();

  constructor(
    private tcb: Context,
    private scope: Scope,
    private block: IfBlock,
  ) {
    super();
  }

  override get optional() {
    return false;
  }

  override execute(): null {
    const root = this.generateBranch(0);
    root && this.scope.addStatement(root);
    return null;
  }

  private generateBranch(index: number): TcbExpr | undefined {
    const branch = this.block.branches[index];

    if (!branch) {
      return undefined;
    }

    // If the expression is null, it means that it's an `else` statement.
    if (branch.expression === null) {
      const branchScope = this.getBranchScope(this.scope, branch, index);
      return new TcbExpr(`{\n${getStatementsBlock(branchScope.render())}}`);
    }

    // We process the expression first in the parent scope, but create a scope around the block
    // that the body will inherit from. We do this, because we need to declare a separate variable
    // for the case where the expression has an alias _and_ because we need the processed
    // expression when generating the guard for the body.
    const outerScope = this.scope.createChildScope(this.scope, branch, [], null);
    outerScope.render().forEach((stmt) => this.scope.addStatement(stmt));
    this.expressionScopes.set(branch, outerScope);

    let expression = tcbExpression(branch.expression, this.tcb, this.scope);
    if (branch.expressionAlias !== null) {
      expression = new TcbExpr(
        `(${expression.print()}) && ${outerScope.resolve(branch.expressionAlias).print()}`,
      );
    }
    const bodyScope = this.getBranchScope(outerScope, branch, index);
    const ifStatement = `if (${expression.print()}) {\n${getStatementsBlock(bodyScope.render())}}`;
    const elseBranch = this.generateBranch(index + 1);

    return new TcbExpr(ifStatement + (elseBranch ? ' else ' + elseBranch.print() : ''));
  }

  private getBranchScope(parentScope: Scope, branch: IfBlockBranch, index: number): Scope {
    const checkBody = this.tcb.env.config.checkControlFlowBodies;
    return this.scope.createChildScope(