Headers API constructor and methods

[malisas]

This PR fills out the constructor and the delete, get, has, and set methods for the Headers API. Addresses issue #11897 .

The PR also rewrites the append method to support hyper::header::Headers's HashMap insert method, which overwrites entries instead of appending.
As a result of this, for a given header name there is at most one value in the inner "header list"/HashMap. Multiple values for the same name are comma-delimited.

There are still a few TODOs:

• Support OpenEndedDictionary<ByteString> as a possible HeadersInit value. OpenEndedDictionary is a future IDL construct.
• Support iterable<ByteString, ByteString>. Related issue: #12628
• Values are comma-delimited, except for values with the name set-cookie, which are newline-delimited. This is because values for set-cookie are allowed to contain inner commas. This violates the spec.
• The TODOs from PR #12467 regarding value parsing also still need to be resolved.

---

• ./mach build -d does not report any errors
• ./mach test-tidy does not report any errors
• These changes fix #__ (github issue number if applicable).

• There are tests for these changes OR
• These changes do not require tests because tests for the Headers API already exists, but this commit does not implement the interface fully. The tests will fail.

---

This change is

[highfive]

Heads up! This PR modifies the following files:

• @KiChjang: components/script/dom/webidls/Headers.webidl, components/script/dom/headers.rs

[highfive]

Warning

• These commits modify script code, but no tests are modified. Please consider adding a test!

[malisas]

r? @jdm

[fitzgen]

cc myself

[jdm]

Great work! I've also submitted #12636 which will allow us to verify at least some of these changes against automated tests.
-S-awaiting-review +S-needs-code-changes

---

Reviewed 2 of 2 files at r1.
Review status: all files reviewed at latest revision, 12 unresolved discussions.

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components/script/dom/headers.rs, line 46 [r1] (raw file):

    // https://fetch.spec.whatwg.org/#concept-headers-fill
    pub fn new(global: GlobalRef, init: Option<HeadersBinding::HeadersInit>)
               -> Result<Root<Headers>, Error> {

This can be Fallible<Root<Header>> instead.

---

components/script/dom/headers.rs, line 47 [r1] (raw file):

    pub fn new(global: GlobalRef, init: Option<HeadersBinding::HeadersInit>)
               -> Result<Root<Headers>, Error> {
        let domHeadersNew = reflect_dom_object(box Headers::new_inherited(), global, HeadersBinding::Wrap);

Let's call this dom_headers_new.

---

components/script/dom/headers.rs, line 52 [r1] (raw file):

            Some(HeadersOrByteStringSequenceSequence::Headers(h)) => {
                // headerListCopy has type hyper::header::Headers
                let headerListCopy = h.header_list.clone();

Traditional Servo code style is to name this header_list_copy instead.

---

components/script/dom/headers.rs, line 53 [r1] (raw file):

                // headerListCopy has type hyper::header::Headers
                let headerListCopy = h.header_list.clone();
                for header in headerListCopy.borrow().iter() {

for header in &headerListCopy.borrow() {

---

components/script/dom/headers.rs, line 70 [r1] (raw file):

                    } else {
                        return Err(Error::Type(
                            "Each inner Vec<ByteString> in HeadersInit must have length 2"

format!("Each header object must be a sequence of length 2 - found one with length {}", seq.len())

---

components/script/dom/headers.rs, line 122 [r1] (raw file):

        // "set-cookie" values allow commas, so we use a different delimiter.
        if &*valid_name == "set-cookie" {
            combined_value.push(b"\n"[0]);

This change isn't part of the fetch specification, so this isn't compatible with the Headers implementation in other browsers. We should remove the special case here and file an issue against the Fetch specification.

---

components/script/dom/headers.rs, line 132 [r1] (raw file):

    // https://fetch.spec.whatwg.org/#dom-headers-delete
    fn Delete(&self, name: ByteString) -> Result<(), Error> {

This can return ErrorResult instead.

---

components/script/dom/headers.rs, line 157 [r1] (raw file):

    // https://fetch.spec.whatwg.org/#dom-headers-get
    fn Get(&self, name: ByteString) -> Result<Option<ByteString>, Error> {

This can use Fallible.

---

components/script/dom/headers.rs, line 165 [r1] (raw file):

        // TODO header fields with a name of "set-cookie" will be
        // returned as newline-delimited values. This
        // goes against the spec, which requires commas:

We should remove this note when we remove the spec-incompatible behaviour.

---

components/script/dom/headers.rs, line 167 [r1] (raw file):

        // goes against the spec, which requires commas:
        // https://fetch.spec.whatwg.org/#concept-header-value-combined
        match self.header_list.borrow_mut().get_raw(&valid_name) {

Ok(self.header_list.borrow().get_raw(&valid_name).map(|v| {
    ByteString::new(v[0].clone())
}))

---

components/script/dom/headers.rs, line 174 [r1] (raw file):

    // https://fetch.spec.whatwg.org/#dom-headers-has
    fn Has(&self, name: ByteString) -> Result<bool, Error> {

Fallible.

---

components/script/dom/headers.rs, line 183 [r1] (raw file):

    // https://fetch.spec.whatwg.org/#dom-headers-set
    fn Set(&self, name: ByteString, value: ByteString) -> Result<(), Error> {

Fallible.

---

Comments from Reviewable

[jdm]

@bors-servo: try

[bors-servo]

⌛ Trying commit 51cfea3 with merge 8533327...

[bors-servo]

💔 Test failed - linux-rel

[highfive]

  ▶ Unexpected subtest result in /fetch/api/headers/headers-basic.html:
  └ PASS [expected FAIL] Create headers from no parameter

  ▶ Unexpected subtest result in /fetch/api/headers/headers-basic.html:
  └ PASS [expected FAIL] Create headers from undefined parameter

  ▶ Unexpected subtest result in /fetch/api/headers/headers-errors.html:
  └ PASS [expected FAIL] Check headers get with an invalid name invalid\u0100

  ▶ Unexpected subtest result in /fetch/api/headers/headers-errors.html:
  └ PASS [expected FAIL] Check headers get with an invalid name [object Object]

  ▶ Unexpected subtest result in /fetch/api/headers/headers-errors.html:
  └ PASS [expected FAIL] Check headers delete with an invalid name invalid\u0100

  ▶ Unexpected subtest result in /fetch/api/headers/headers-errors.html:
  └ PASS [expected FAIL] Check headers delete with an invalid name [object Object]

  ▶ Unexpected subtest result in /fetch/api/headers/headers-errors.html:
  └ PASS [expected FAIL] Check headers has with an invalid name invalid\u0100

  ▶ Unexpected subtest result in /fetch/api/headers/headers-errors.html:
  └ PASS [expected FAIL] Check headers has with an invalid name [object Object]

  ▶ Unexpected subtest result in /fetch/api/headers/headers-errors.html:
  └ PASS [expected FAIL] Check headers set with an invalid name invalid\u0100

  ▶ Unexpected subtest result in /fetch/api/headers/headers-errors.html:
  └ PASS [expected FAIL] Check headers set with an invalid name [object Object]

  ▶ Unexpected subtest result in /fetch/api/headers/headers-errors.html:
  └ PASS [expected FAIL] Check headers set with an invalid value invalid\u0100

  ▶ Unexpected subtest result in /fetch/api/headers/headers-errors.html:
  └ PASS [expected FAIL] Check headers append with an invalid name invalid\u0100

  ▶ Unexpected subtest result in /fetch/api/headers/headers-errors.html:
  └ PASS [expected FAIL] Check headers append with an invalid name [object Object]

  ▶ Unexpected subtest result in /fetch/api/headers/headers-errors.html:
  └ PASS [expected FAIL] Check headers append with an invalid value invalid\u0100

  ▶ OK [expected TIMEOUT] /fetch/api/headers/headers-structure.html

  ▶ Unexpected s</span><span class="stdout">ubtest result in /fetch/api/headers/headers-structure.html:
  │ FAIL [expected PASS] Headers has entries method
  │   → assert_true: headers has entries method expected true got false
  │ FAIL [expected PASS] Headers has keys method
  │   → assert_true: headers has keys method expected true got false
  │ FAIL [expected PASS] Headers has values method
  │   → assert_true: headers has values method expected true got false
  │ 
  │ @http://web-platform.test:8000/fetch/api/headers/headers-structure.html:14:13
  │ Test.prototype.step@http://web-platform.test:8000/resources/testharness.js:1402:20
  │ test@http://web-platform.test:8000/resources/testharness.js:500:9
  └ @http://web-platform.test:8000/fetch/api/headers/headers-structure.html:13:11

[malisas]

Thanks @jdm for the feedback!
I made the changes -- still need to file the Fetch spec issue though.

[malisas]

(and here is the filed issue about the Set-Cookie headers exception)

[jdm]

The only remaining change is to update the expected test results and squash the commits together.
-S-awaiting-review +S-needs-code-changes +S-needs-squash

---

Reviewed 1 of 1 files at r2.
Review status: 1 of 2 files reviewed at latest revision, all discussions resolved.

---

Comments from Reviewable

[jdm]

@bors-servo: r+

[bors-servo]

📌 Commit e631d3a has been approved by jdm

[bors-servo]

⌛ Testing commit e631d3a with merge 1ce4be8...

[bors-servo]

☀️ Test successful - arm32, arm64, linux-dev, linux-rel, mac-dev-unit, mac-rel-css, mac-rel-wpt, windows-dev