You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
73 lines
2.2 KiB
73 lines
2.2 KiB
// @flow
|
|
|
|
import type {Type} from '../types.js';
|
|
import type {Expression, SerializedExpression} from '../expression.js';
|
|
import type ParsingContext from '../parsing_context.js';
|
|
import type EvaluationContext from '../evaluation_context.js';
|
|
|
|
class Let implements Expression {
|
|
type: Type;
|
|
bindings: Array<[string, Expression]>;
|
|
result: Expression;
|
|
|
|
constructor(bindings: Array<[string, Expression]>, result: Expression) {
|
|
this.type = result.type;
|
|
this.bindings = [].concat(bindings);
|
|
this.result = result;
|
|
}
|
|
|
|
evaluate(ctx: EvaluationContext): any {
|
|
return this.result.evaluate(ctx);
|
|
}
|
|
|
|
eachChild(fn: (_: Expression) => void) {
|
|
for (const binding of this.bindings) {
|
|
fn(binding[1]);
|
|
}
|
|
fn(this.result);
|
|
}
|
|
|
|
static parse(args: $ReadOnlyArray<mixed>, context: ParsingContext): ?Let {
|
|
if (args.length < 4)
|
|
return context.error(`Expected at least 3 arguments, but found ${args.length - 1} instead.`);
|
|
|
|
const bindings: Array<[string, Expression]> = [];
|
|
for (let i = 1; i < args.length - 1; i += 2) {
|
|
const name = args[i];
|
|
|
|
if (typeof name !== 'string') {
|
|
return context.error(`Expected string, but found ${typeof name} instead.`, i);
|
|
}
|
|
|
|
if (/[^a-zA-Z0-9_]/.test(name)) {
|
|
return context.error(`Variable names must contain only alphanumeric characters or '_'.`, i);
|
|
}
|
|
|
|
const value = context.parse(args[i + 1], i + 1);
|
|
if (!value) return null;
|
|
|
|
bindings.push([name, value]);
|
|
}
|
|
|
|
const result = context.parse(args[args.length - 1], args.length - 1, context.expectedType, bindings);
|
|
if (!result) return null;
|
|
|
|
return new Let(bindings, result);
|
|
}
|
|
|
|
outputDefined(): boolean {
|
|
return this.result.outputDefined();
|
|
}
|
|
|
|
serialize(): SerializedExpression {
|
|
const serialized = ["let"];
|
|
for (const [name, expr] of this.bindings) {
|
|
serialized.push(name, expr.serialize());
|
|
}
|
|
serialized.push(this.result.serialize());
|
|
return serialized;
|
|
}
|
|
}
|
|
|
|
export default Let;
|