cleanup(web, fetch): dedupe minesniff / "extract a MIME type" algorit…

…hm (denoland#14044) Closes denoland#14002
crowlKats · Mar 20, 2022 · 593801e · 593801e
1 parent 0bc286a
commit 593801e
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Showing 4 changed files with 55 additions and 71 deletions.
diff --git a/ext/fetch/23_request.js b/ext/fetch/23_request.js
@@ -18,7 +18,7 @@
  const { guardFromHeaders } = window.__bootstrap.headers;
  const { mixinBody, extractBody } = window.__bootstrap.fetchBody;
  const { getLocationHref } = window.__bootstrap.location;
- const mimesniff = window.__bootstrap.mimesniff;
+ const { extractMimeType } = window.__bootstrap.mimesniff;
  const { blobFromObjectUrl } = window.__bootstrap.file;
  const {
  headersFromHeaderList,
@@ -32,9 +32,6 @@
  ArrayPrototypeMap,
  ArrayPrototypeSlice,
  ArrayPrototypeSplice,
- MapPrototypeHas,
- MapPrototypeGet,
- MapPrototypeSet,
  ObjectKeys,
  ObjectPrototypeIsPrototypeOf,
  RegExpPrototypeTest,
@@ -174,41 +171,11 @@
  /** @type {AbortSignal} */
  [_signal];
  get [_mimeType]() {
- let charset = null;
- let essence = null;
- let mimeType = null;
  const values = getDecodeSplitHeader(
  headerListFromHeaders(this[_headers]),
  "Content-Type",
  );
- if (values === null) return null;
- for (const value of values) {
- const temporaryMimeType = mimesniff.parseMimeType(value);
- if (
- temporaryMimeType === null ||
- mimesniff.essence(temporaryMimeType) == "*/*"
- ) {
- continue;
- }
- mimeType = temporaryMimeType;
- if (mimesniff.essence(mimeType) !== essence) {
- charset = null;
- const newCharset = MapPrototypeGet(mimeType.parameters, "charset");
- if (newCharset !== undefined) {
- charset = newCharset;
- }
- essence = mimesniff.essence(mimeType);
- } else {
- if (
- MapPrototypeHas(mimeType.parameters, "charset") === null &&
- charset !== null
- ) {
- MapPrototypeSet(mimeType.parameters, "charset", charset);
- }
- }
- }
- if (mimeType === null) return null;
- return mimeType;
+ return extractMimeType(values);
  }
  get [_body]() {
  return this[_request].body;

diff --git a/ext/fetch/23_response.js b/ext/fetch/23_response.js
@@ -18,7 +18,7 @@
  const { HTTP_TAB_OR_SPACE, regexMatcher } = window.__bootstrap.infra;
  const { extractBody, mixinBody } = window.__bootstrap.fetchBody;
  const { getLocationHref } = window.__bootstrap.location;
- const mimesniff = window.__bootstrap.mimesniff;
+ const { extractMimeType } = window.__bootstrap.mimesniff;
  const { URL } = window.__bootstrap.url;
  const {
  getDecodeSplitHeader,
@@ -30,9 +30,6 @@
  const {
  ArrayPrototypeMap,
  ArrayPrototypePush,
- MapPrototypeHas,
- MapPrototypeGet,
- MapPrototypeSet,
  ObjectPrototypeIsPrototypeOf,
  RangeError,
  RegExp,
@@ -162,41 +159,11 @@
 
  class Response {
  get [_mimeType]() {
- let charset = null;
- let essence = null;
- let mimeType = null;
  const values = getDecodeSplitHeader(
  headerListFromHeaders(this[_headers]),
  "Content-Type",
  );
- if (values === null) return null;
- for (const value of values) {
- const temporaryMimeType = mimesniff.parseMimeType(value);
- if (
- temporaryMimeType === null ||
- mimesniff.essence(temporaryMimeType) == "*/*"
- ) {
- continue;
- }
- mimeType = temporaryMimeType;
- if (mimesniff.essence(mimeType) !== essence) {
- charset = null;
- const newCharset = MapPrototypeGet(mimeType.parameters, "charset");
- if (newCharset !== undefined) {
- charset = newCharset;
- }
- essence = mimesniff.essence(mimeType);
- } else {
- if (
- MapPrototypeHas(mimeType.parameters, "charset") === null &&
- charset !== null
- ) {
- MapPrototypeSet(mimeType.parameters, "charset", charset);
- }
- }
- }
- if (mimeType === null) return null;
- return mimeType;
+ return extractMimeType(values);
  }
  get [_body]() {
  return this[_response].body;

diff --git a/ext/web/01_mimesniff.js b/ext/web/01_mimesniff.js
@@ -12,6 +12,7 @@
  const {
  ArrayPrototypeIncludes,
  Map,
+ MapPrototypeGet,
  MapPrototypeHas,
  MapPrototypeSet,
  RegExpPrototypeTest,
@@ -207,5 +208,51 @@
  return serialization;
  }
 
- window.__bootstrap.mimesniff = { parseMimeType, essence, serializeMimeType };
+ /**
+ * Part of the Fetch spec's "extract a MIME type" algorithm
+ * (https://fetch.spec.whatwg.org/#concept-header-extract-mime-type).
+ * @param {string[] | null} headerValues The result of getting, decoding and
+ * splitting the "Content-Type" header.
+ * @returns {MimeType | null}
+ */
+ function extractMimeType(headerValues) {
+ if (headerValues === null) return null;
+
+ let charset = null;
+ let essence_ = null;
+ let mimeType = null;
+ for (const value of headerValues) {
+ const temporaryMimeType = parseMimeType(value);
+ if (
+ temporaryMimeType === null ||
+ essence(temporaryMimeType) == "*/*"
+ ) {
+ continue;
+ }
+ mimeType = temporaryMimeType;
+ if (essence(mimeType) !== essence_) {
+ charset = null;
+ const newCharset = MapPrototypeGet(mimeType.parameters, "charset");
+ if (newCharset !== undefined) {
+ charset = newCharset;
+ }
+ essence_ = essence(mimeType);
+ } else {
+ if (
+ !MapPrototypeHas(mimeType.parameters, "charset") &&
+ charset !== null
+ ) {
+ MapPrototypeSet(mimeType.parameters, "charset", charset);
+ }
+ }
+ }
+ return mimeType;
+ }
+
+ window.__bootstrap.mimesniff = {
+ parseMimeType,
+ essence,
+ serializeMimeType,
+ extractMimeType,
+ };
 })(this);
diff --git a/ext/web/internal.d.ts b/ext/web/internal.d.ts
@@ -60,6 +60,9 @@ declare namespace globalThis {
  declare function parseMimeType(input: string): MimeType | null;
  declare function essence(mimeType: MimeType): string;
  declare function serializeMimeType(mimeType: MimeType): string;
+ declare function extractMimeType(
+ headerValues: string[] | null,
+ ): MimeType | null;
  }
 
  declare var eventTarget: {