X-Git-Url: https://git.ladys.computer/Pisces/blobdiff_plain/2989f964f0325a2d9c9294a8d3dab722313d5518..a63ba5294bd5cc847a192f6737bc386bfe7187f8:/string.js?ds=sidebyside

diff --git a/string.js b/string.js
index d65d294..fb41e62 100644
--- a/string.js
+++ b/string.js
@@ -8,7 +8,188 @@
 // file, You can obtain one at <https://mozilla.org/MPL/2.0/>.
 
 import { bind, call, identity, makeCallable } from "./function.js";
-import { getPrototype, objectCreate } from "./object.js";
+import {
+  defineOwnProperties,
+  getPrototype,
+  objectCreate,
+  setPrototype,
+} from "./object.js";
+
+export const {
+  /**
+   * A RegExp·like object which only matches entire strings.
+   *
+   * 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.
+   */
+  Matcher,
+} = (() => {
+  const RE = RegExp;
+  const { prototype: rePrototype } = RE;
+  const { exec: reExec, toString: reToString } = rePrototype;
+  const getDotAll =
+    Object.getOwnPropertyDescriptor(rePrototype, "dotAll").get;
+  const getGlobal =
+    Object.getOwnPropertyDescriptor(rePrototype, "global").get;
+  const getHasIndices =
+    Object.getOwnPropertyDescriptor(rePrototype, "hasIndices").get;
+  const getIgnoreCase =
+    Object.getOwnPropertyDescriptor(rePrototype, "ignoreCase").get;
+  const getMultiline =
+    Object.getOwnPropertyDescriptor(rePrototype, "multiline").get;
+  const getSource =
+    Object.getOwnPropertyDescriptor(rePrototype, "source").get;
+  const getSticky =
+    Object.getOwnPropertyDescriptor(rePrototype, "sticky").get;
+  const getUnicode =
+    Object.getOwnPropertyDescriptor(rePrototype, "unicode").get;
+
+  const Matcher = class extends identity {
+    #regExp;
+
+    /**
+     * Constructs a new Matcher from the provided source.
+     *
+     * If the provided source is a regular expression, then it must
+     * have the unicode flag set. Otherwise, it is interpreted as the
+     * string source of a regular expression with the unicode flag set.
+     *
+     * Other flags are taken from the provided regular expression
+     * object, if any are present.
+     *
+     * A name for the matcher may be provided as the second argument.
+     *
+     * ☡ 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 `)$` if you don’t want nongreedy
+     * regular expressions to fail when shorter matches are possible.
+     */
+    constructor(source, name = undefined) {
+      super(
+        ($) => {
+          if (typeof $ !== "string") {
+            // The provided value is not a string.
+            return false;
+          } 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.
+            regExp.lastIndex = 0;
+            return call(reExec, regExp, [$])?.[0] === $;
+          }
+        },
+      );
+      const regExp = this.#regExp = (() => {
+        try {
+          call(reExec, source, [""]); // throws if source not a RegExp
+        } catch {
+          return new RE(`${source}`, "u");
+        }
+        const unicode = call(getUnicode, source, []);
+        if (!unicode) {
+          // The provided regular expression does not have a unicode
+          // flag.
+          throw new TypeError(
+            `Piscēs: Cannot create Matcher from non‐Unicode RegExp: ${source}`,
+          );
+        } else {
+          // The provided regular expression has a unicode flag.
+          return new RE(source);
+        }
+      })();
+      return defineOwnProperties(
+        setPrototype(this, matcherPrototype),
+        {
+          lastIndex: {
+            configurable: false,
+            enumerable: false,
+            value: 0,
+            writable: false,
+          },
+          name: {
+            value: name != null
+              ? `${name}`
+              : `Matcher(${call(reToString, regExp, [])})`,
+          },
+        },
+      );
+    }
+
+    /** Gets whether the dotAll flag is present on this Matcher. */
+    get dotAll() {
+      return call(getDotAll, this.#regExp, []);
+    }
+
+    /**
+     * Executes this Matcher on the provided value and returns the
+     * result if there is a match, or null otherwise.
+     *
+     * Matchers only match if they can match the entire value on the
+     * first attempt.
+     */
+    exec($) {
+      const regExp = this.#regExp;
+      const string = `${$}`;
+      regExp.lastIndex = 0;
+      const result = call(reExec, regExp, [string]);
+      if (result?.[0] === string) {
+        // The entire string was matched.
+        return result;
+      } else {
+        // The entire string was not matched.
+        return null;
+      }
+    }
+
+    /** Gets whether the global flag is present on this Matcher. */
+    get global() {
+      return call(getGlobal, this.#regExp, []);
+    }
+
+    /** Gets whether the hasIndices flag is present on this Matcher. */
+    get hasIndices() {
+      return call(getHasIndices, this.#regExp, []);
+    }
+
+    /** Gets whether the ignoreCase flag is present on this Matcher. */
+    get ignoreCase() {
+      return call(getIgnoreCase, this.#regExp, []);
+    }
+
+    /** Gets whether the multiline flag is present on this Matcher. */
+    get multiline() {
+      return call(getMultiline, this.#regExp, []);
+    }
+
+    /** Gets the regular expression source for this Matcher. */
+    get source() {
+      return call(getSource, this.#regExp, []);
+    }
+
+    /** Gets whether the sticky flag is present on this Matcher. */
+    get sticky() {
+      return call(getSticky, this.#regExp, []);
+    }
+
+    /**
+     * Gets whether the unicode flag is present on this Matcher.
+     *
+     * ※ This will always be true.
+     */
+    get unicode() {
+      return call(getUnicode, this.#regExp, []);
+    }
+  };
+  const matcherPrototype = setPrototype(
+    Matcher.prototype,
+    rePrototype,
+  );
+
+  return { Matcher };
+})();
 
 export const {
   /**