From: Lady Date: Thu, 8 Sep 2022 03:17:51 +0000 (-0700) Subject: Add support for constraints to Matcher X-Git-Tag: 0.1.4^0 X-Git-Url: https://git.ladys.computer/Pisces/commitdiff_plain/ecf679353a1fb5fde431eca37c70515b64eb3d05?ds=sidebyside Add support for constraints to Matcher --- diff --git a/string.js b/string.js index 100f0bd..8c858cd 100644 --- a/string.js +++ b/string.js @@ -17,12 +17,14 @@ import { export const { /** - * A RegExp·like object which only matches entire strings. + * A RegExp·like object which only matches entire strings, and may + * have additional constraints specified. * * Matchers are callable objects and will return true if they are * called with a string that they match, and false otherwise. * Matchers will always return false if called with nonstrings, - * although other methods like `exec` may still return true. + * although other methods like `exec` coerce their arguments and may + * still return true. */ Matcher, } = (() => { @@ -47,6 +49,7 @@ export const { Object.getOwnPropertyDescriptor(rePrototype, "unicode").get; const Matcher = class extends identity { + #constraint; #regExp; /** @@ -61,13 +64,20 @@ export const { * * A name for the matcher may be provided as the second argument. * + * A callable constraint on acceptable inputs may be provided as a + * third argument. If provided, it will be called with two + * arguments whenever a match appears successful: first, the string + * being matched, and second, the Matcher object itself. If the + * return value of this call is falsey, then the match will be + * considered a failure. + * * ☡ If the provided source regular expression uses nongreedy * quantifiers, it may not match the whole string even if a match * with the whole string is possible. Surround the regular * expression with `^(?:` and `)$` if you don’t want nongreedy * regular expressions to fail when shorter matches are possible. */ - constructor(source, name = undefined) { + constructor(source, name = undefined, constraint = null) { super( ($) => { if (typeof $ !== "string") { @@ -76,9 +86,11 @@ export const { } else { // The provided value is a string. Set the `lastIndex` of // the regular expression to 0 and see if the first attempt - // at a match matches the whole string. + // at a match matches the whole string and passes the + // provided constraint (if present). regExp.lastIndex = 0; - return call(reExec, regExp, [$])?.[0] === $; + return call(reExec, regExp, [$])?.[0] === $ && + (constraint === null || constraint($, this)); } }, ); @@ -100,22 +112,29 @@ export const { return new RE(source); } })(); - return defineOwnProperties( - setPrototype(this, matcherPrototype), - { - lastIndex: { - configurable: false, - enumerable: false, - value: 0, - writable: false, - }, - name: { - value: name != null - ? `${name}` - : `Matcher(${call(reToString, regExp, [])})`, + if (constraint !== null && typeof constraint !== "function") { + throw new TypeError( + "Piscēs: Cannot construct Matcher: Constraint is not callable.", + ); + } else { + this.#constraint = constraint; + return defineOwnProperties( + setPrototype(this, matcherPrototype), + { + lastIndex: { + configurable: false, + enumerable: false, + value: 0, + writable: false, + }, + name: { + value: name != null + ? `${name}` + : `Matcher(${call(reToString, regExp, [])})`, + }, }, - }, - ); + ); + } } /** Gets whether the dotAll flag is present on this Matcher. */ @@ -132,14 +151,20 @@ export const { */ exec($) { const regExp = this.#regExp; + const constraint = this.#constraint; const string = `${$}`; regExp.lastIndex = 0; const result = call(reExec, regExp, [string]); - if (result?.[0] === string) { - // The entire string was matched. + if ( + result?.[0] === string && + (constraint === null || constraint(string, this)) + ) { + // The entire string was matched and the constraint, if + // present, returned a truthy value. return result; } else { - // The entire string was not matched. + // The entire string was not matched or the constraint returned + // a falsey value. return null; } } diff --git a/string.test.js b/string.test.js index 0af3e32..52e848c 100644 --- a/string.test.js +++ b/string.test.js @@ -10,10 +10,13 @@ import { assert, assertEquals, + assertSpyCall, + assertSpyCalls, assertStrictEquals, assertThrows, describe, it, + spy, } from "./dev-deps.js"; import { asciiLowercase, @@ -60,6 +63,10 @@ describe("Matcher", () => { assert(new Matcher("") instanceof RegExp); }); + it("[[Construct]] throws when provided with a noncallable, non·null third argument", () => { + assertThrows(() => new Matcher("", undefined, "failure")); + }); + describe("::dotAll", () => { it("[[Get]] returns true when the dotAll flag is present", () => { assertStrictEquals(new Matcher(/(?:)/su).dotAll, true); @@ -76,10 +83,47 @@ describe("Matcher", () => { [...new Matcher(/.(?(?:.(?=.))*)(.)?/u).exec("success")], ["success", "ucces", "s"], ); + assertEquals( + [...new Matcher( + /.(?(?:.(?=.))*)(.)?/u, + undefined, + ($) => $ === "success", + ).exec("success")], + ["success", "ucces", "s"], + ); + }); + + it("[[Call]] calls the constraint if the match succeeds", () => { + const constraint = spy((_) => true); + const matcher = new Matcher(".*", undefined, constraint); + matcher.exec({ + toString() { + return "etaoin"; + }, + }); + assertSpyCalls(constraint, 1); + assertSpyCall(constraint, 0, { + args: ["etaoin", matcher], + self: undefined, + }); + }); + + it("[[Call]] does not call the constraint if the match fails", () => { + const constraint = spy((_) => true); + const matcher = new Matcher("", undefined, constraint); + matcher.exec("failure"); + assertSpyCalls(constraint, 0); }); it("[[Call]] returns null given a partial match", () => { - assertEquals(new Matcher("").exec("failure"), null); + assertStrictEquals(new Matcher("").exec("failure"), null); + }); + + it("[[Call]] returns null if the constraint fails", () => { + assertStrictEquals( + new Matcher(".*", undefined, () => false).exec(""), + null, + ); }); }); @@ -150,12 +194,43 @@ describe("Matcher", () => { it("[[Call]] returns true for a complete match", () => { assertStrictEquals(new Matcher("")(""), true); assertStrictEquals(new Matcher(/.*/su)("success\nyay"), true); + assertStrictEquals( + new Matcher(/.*/su, undefined, ($) => $ === "success")( + "success", + ), + true, + ); + }); + + it("[[Call]] calls the constraint if the match succeeds", () => { + const constraint = spy((_) => true); + const matcher = new Matcher(".*", undefined, constraint); + matcher("etaoin"); + assertSpyCalls(constraint, 1); + assertSpyCall(constraint, 0, { + args: ["etaoin", matcher], + self: undefined, + }); + }); + + it("[[Call]] does not call the constraint if the match fails", () => { + const constraint = spy((_) => true); + const matcher = new Matcher("", undefined, constraint); + matcher("failure"); + assertSpyCalls(constraint, 0); }); it("[[Call]] returns false for a partial match", () => { assertStrictEquals(new Matcher("")("failure"), false); assertStrictEquals(new Matcher(/.*/u)("failure\nno"), false); }); + + it("[[Call]] returns false if the constraint fails", () => { + assertStrictEquals( + new Matcher(".*", undefined, () => false)(""), + false, + ); + }); }); describe("~lastIndex", () => {