Method getReference

src/interpreter/index.ts:1713–1772

(dest: Ast.Expression, scope: Scope, callStack: readonly CallInfo[])

	@autobind
	private async getReference(dest: Ast.Expression, scope: Scope, callStack: readonly CallInfo[]): Promise<Reference | Control> {
		switch (dest.type) {
			case 'identifier': {
				return Reference.variable(dest.name, scope);
			}
			case 'index': {
				const assignee = await this._eval(dest.target, scope, callStack);
				if (isControl(assignee)) {
					return assignee;
				}
				const i = await this._eval(dest.index, scope, callStack);
				if (isControl(i)) {
					return i;
				}
				if (isArray(assignee)) {
					assertNumber(i);
					return Reference.index(assignee, i.value);
				} else if (isObject(assignee)) {
					assertString(i);
					return Reference.prop(assignee, i.value);
				} else {
					throw new AiScriptRuntimeError(`Cannot read prop (${reprValue(i)}) of ${assignee.type}.`);
				}
			}
			case 'prop': {
				const assignee = await this._eval(dest.target, scope, callStack);
				if (isControl(assignee)) {
					return assignee;
				}
				assertObject(assignee);

				return Reference.prop(assignee, dest.name);
			}
			case 'arr': {
				const items: Reference[] = [];
				for (const item of dest.value) {
					const ref = await this.getReference(item, scope, callStack);
					if (isControl(ref)) {
						return ref;
					}
					items.push(ref);
				}
				return Reference.arr(items);
			}
			case 'obj': {
				const entries = new Map<string, Reference>();
				for (const [key, item] of dest.value.entries()) {
					const ref = await this.getReference(item, scope, callStack);
					if (isControl(ref)) {
						return ref;
					}
					entries.set(key, ref);
				}
				return Reference.obj(entries);
			}
			default: {
				throw new AiScriptRuntimeError('The left-hand side of an assignment expression must be a variable or a property/index access.');
			}