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122 lines
2.8 KiB
122 lines
2.8 KiB
import is from '@sindresorhus/is';
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import {Ow} from '../..';
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import {ArgumentError} from '../argument-error';
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import {BasePredicate, testSymbol} from './base-predicate';
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import {not} from '../operators/not';
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/**
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* @hidden
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*/
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export interface Validator<T> {
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message(value: T, label?: string, result?: any): string;
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validator(value: T): any;
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}
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/**
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* @hidden
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*/
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export interface Context<T> {
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validators: Validator<T>[];
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label?: string;
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}
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/**
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* @hidden
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*/
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export const validatorSymbol = Symbol('validators');
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/**
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* @hidden
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*/
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export class Predicate<T = any> implements BasePredicate<T> {
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constructor(
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private readonly type: string,
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private readonly context: Context<T> = {
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validators: []
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}
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) {
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const x = this.type[0].toLowerCase() + this.type.slice(1);
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this.addValidator({
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message: value => {
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// We do not include type in this label as we do for other messages, because it would be redundant.
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const label = this.context.label || 'argument';
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return `Expected ${label} to be of type \`${this.type}\` but received type \`${is(value)}\``;
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},
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validator: value => (is as any)[x](value)
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});
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}
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/**
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* @hidden
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*/
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// tslint:disable completed-docs
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[testSymbol](value: T, main: Ow) {
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const label = this.context.label
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? `${this.type} ${this.context.label}`
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: this.type;
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for (const {validator, message} of this.context.validators) {
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const result = validator(value);
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if (typeof result !== 'boolean' || !result) {
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// TODO: Modify the stack output to show the original `ow()` call instead of this `throw` statement
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throw new ArgumentError(message(value, label, result), main);
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}
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}
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}
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/**
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* @hidden
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*/
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get [validatorSymbol]() {
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return this.context.validators;
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}
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/**
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* Invert the following validators.
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*/
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get not(): this {
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return not(this);
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}
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/**
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* Assign a label to this predicate for use in error messages.
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*
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* @param value Label to assign.
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*/
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label(value: string) {
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this.context.label = `\`${value}\``;
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return this;
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}
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/**
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* Test if the value matches a custom validation function. The validation function should return `true` if the value
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* passes the function. If the function either returns `false` or a string, the function fails and the string will be
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* used as error message.
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*
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* @param fn Validation function.
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*/
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is(fn: (value: T) => boolean | string) {
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return this.addValidator({
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message: (value, label, error) => (error
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? `(${label}) ${error}`
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: `Expected ${label} \`${value}\` to pass custom validation function`
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),
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validator: value => fn(value)
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});
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}
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/**
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* Register a new validator.
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*
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* @internal
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* @hidden
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* @param validator Validator to register.
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*/
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addValidator(validator: Validator<T>) {
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this.context.validators.push(validator);
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return this;
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}
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}
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