feat(quoted_string): add isQuotedString function

Author: TomokiMiyauci

README.md

@@ -622,6 +622,24 @@ assert(isQuotedPair("\\\xFF"));
 assertFalse(isQuotedPair("\\"));
 ```
 
+### isQuotedString
+
+Whether the input is
+[quoted-string](https://www.rfc-editor.org/rfc/rfc9110.html#section-5.6.4-2).
+
+```ts
+import { isQuotedString } from "https://deno.land/x/http_utils@$VERSION/quoted_string.ts";
+import {
+  assert,
+  assertFalse,
+} from "https://deno.land/std@$VERSION/testing/asserts.ts";
+
+assert(isQuotedString(`""`));
+assert(isQuotedString(`"qdtext"`));
+assert(isQuotedString(`"quoted-pair"`));
+assertFalse(isQuotedString(""));
+```
+
 ## License
 
 Copyright © 2023-present [httpland](https://github.com/httpland).

quoted_string.ts

@@ -1,9 +1,6 @@
 // Copyright 2023-latest the httpland authors. All rights reserved. MIT license.
 // This module is browser compatible.
 
-// export function isQuotedString(input: string): input is QuotedString {
-// }
-
 /**
  * ```abnf
  * obs-text = %x80-FF
@@ -33,6 +30,7 @@ export function isQdtext(input: string): boolean {
 
 /**
  * ```abnf
+ * obs-text = %x80-FF
  * quoted-pair = "\" ( HTAB / SP / VCHAR / obs-text )
  * ```
  */
@@ -59,3 +57,37 @@ export type QuotedPair = `\\${string}`;
 export function isQuotedPair(input: string): input is QuotedPair {
   return reQuotedPair.test(input);
 }
+
+/** [quoted-string](https://www.rfc-editor.org/rfc/rfc9110.html#section-5.6.4-2). */
+export type QuotedString = `"${string}"`;
+
+/**
+ * ```abnf
+ * quoted-string  = DQUOTE *( qdtext / quoted-pair ) DQUOTE
+ * qdtext         = HTAB / SP / %x21 / %x23-5B / %x5D-7E / obs-text
+ * quoted-pair    = "\" ( HTAB / SP / VCHAR / obs-text )
+ * obs-text       = %x80-FF
+ * ```
+ */
+const reQuotedString =
+  /^"(?:[\t \x21\x23-\x5B\x5D-\x7E\x80-\xFF]|\\[\t \x21-\x7E\x80-\xFF])*?"$/;
+
+/** Whether the input is [quoted-string](https://www.rfc-editor.org/rfc/rfc9110.html#section-5.6.4-2).
+ *
+ * @example
+ * ```ts
+ * import { isQuotedString } from "https://deno.land/x/http_utils@$VERSION/quoted_string.ts";
+ * import {
+ *   assert,
+ *   assertFalse,
+ * } from "https://deno.land/std@$VERSION/testing/asserts.ts";
+ *
+ * assert(isQuotedString(`""`));
+ * assert(isQuotedString(`"qdtext"`));
+ * assert(isQuotedString(`"quoted-pair"`));
+ * assertFalse(isQuotedString(""));
+ * ```
+ */
+export function isQuotedString(input: string): input is QuotedString {
+  return reQuotedString.test(input);
+}

quoted_string_test.ts

@@ -1,4 +1,4 @@
-import { isQdtext, isQuotedPair } from "./quoted_string.ts";
+import { isQdtext, isQuotedPair, isQuotedString } from "./quoted_string.ts";
 import {
   assert,
   assertEquals,
@@ -19,6 +19,18 @@ function charRange(start: string, end: string): string[] {
   );
 }
 
+function slashed(input: string): `\\${string}` {
+  return `\\${input}`;
+}
+
+function quoted(input: string): `"${string}"` {
+  return `"${input}"`;
+}
+
+function next(input: string): string {
+  return String.fromCharCode(input.charCodeAt(0) + 1);
+}
+
 const vchars = charRange("\x21", "\x7E");
 const obsTexts = charRange("\x80", "\xFF");
 
@@ -73,10 +85,6 @@ describe("isQdtext", () => {
 });
 
 describe("isQuotedPair", () => {
-  function slashed(input: string): `\\${string}` {
-    return `\\${input}`;
-  }
-
   it("should return true", () => {
     const table: string[] = [
       "\\\t",
@@ -97,7 +105,7 @@ describe("isQuotedPair", () => {
       ...charRange("\x00", "\x08").map(slashed), // \x09 is "\t"
       ...charRange("\x10", "\x19").map(slashed), // \x20 is " "
       "\\\x7F",
-      "\\" + "\xFF" + 1,
+      "\\" + next("\xFF"),
 
       "\\\x21\x21",
     ];
@@ -107,3 +115,49 @@ describe("isQuotedPair", () => {
     });
   });
 });
+
+describe("isQuotedString", () => {
+  it("should return true", () => {
+    const table: string[] = [
+      quoted(""),
+      quoted("\t"),
+      quoted(" "),
+      quoted("\x21"),
+      ...charRange("\x23", "\x5B").map(quoted),
+      ...charRange("\x5D", "\x7E").map(quoted),
+      ...obsTexts.map(quoted),
+      quoted(slashed("\t")),
+      quoted(slashed(" ")),
+      ...vchars.map(slashed).map(quoted),
+      ...obsTexts.map(slashed).map(quoted),
+
+      quoted(vchars.map(slashed).join("")),
+      quoted(obsTexts.map(slashed).join("")),
+      quoted(obsTexts.join("")),
+      quoted(charRange("\x23", "\x5B").join()),
+      quoted(charRange("\x23", "\x5B").join() + vchars.map(slashed).join("")),
+    ];
+
+    table.forEach((input) => {
+      assert(isQuotedString(input));
+    });
+  });
+
+  it("should return false", () => {
+    const table: string[] = [
+      "",
+      "''",
+      quoted("\\"),
+      quoted("\t\\"),
+      quoted(next("\xFF")),
+      quoted("あ"),
+      quoted(charRange(next("\xFF"), next(next("\xFF"))).join()),
+      quoted(vchars.join("")),
+      obsTexts.map(slashed).join(""),
+    ];
+
+    table.forEach((input) => {
+      assertFalse(isQuotedString(input));
+    });
+  });
+});