Commit graph

63 commits

Author SHA1 Message Date
Matthew Beck
1d3bf59f9a fix(compiler): simplify handling of colon host with a selector list
Update `_convertColonHost` to extract and use only the first argument from a `:host(...)` selector list, ignoring subsequent arguments instead of splitting and duplicating the selector list. Also remove the obsolete test cases from `host_and_host_context_spec.ts`.
2026-05-12 14:25:46 -07:00
Matthew Beck
6de4955124 fix(compiler): remove dedicated support for legacy shadow DOM selectors
Remove `_shadowDOMSelectorsRe` and `_convertShadowDOMSelectors` from `shadow_css.ts` so that `::shadow`, `::content`, `/shadow-deep/`, and `/shadow/` are no longer treated specially or stripped from user CSS. Instead, they are naturally scoped like standard selectors. Also remove the legacy failing test from `shadow_css_spec.ts`.
2026-05-12 14:24:29 -07:00
Matthew Beck
23f0898edb fix(compiler): remove deprecated shadow CSS encapsulation polyfills
Completely remove support for `polyfill-next-selector`, `polyfill-unscoped-rule`, and `polyfill-rule` from `shadow_css.ts`, along with their associated methods and regular expressions. Also delete `polyfills_spec.ts` entirely.
2026-05-12 14:24:02 -07:00
Matthew Beck
770e505f78 fix(compiler): preserve leading commas in animation definitions
Update the regular expression in `_scopeAnimationRule` to prevent absorbing and deleting leading commas after `animation:`. Also remove the corresponding legacy test case from `keyframes_spec.ts`.
2026-05-12 14:22:56 -07:00
Matthew Beck
338bf7d46f fix(compiler): enforce parentheses containing arguments for :host-context
Modify `_colonHostContextRe` and `_hostContextPattern` to strictly process `:host-context` only when parentheses containing at least one non-whitespace argument character are present. Update `_colonHostRe` to explicitly NOT match `:host` when followed by a hyphen. When invoked without parentheses or with empty parentheses, the selector is completely ignored and treated as a standard CSS pseudo-class in the source text. Also update the legacy test case from `host_and_host_context_spec.ts`.
2026-05-12 14:22:19 -07:00
Matt Lewis
5a712d42d1 fix(compiler): prevent shimCssText from adding extra blank lines per CSS comment
The comment placeholder restoration in `shimCssText` appended an unconditional
`+ '\n'` to each non-hash comment replacement. Because `_commentRe` does not
consume the newline that follows a comment in the source, that newline already
remains in `cssText`. The extra `'\n'` was therefore inserted on top of the
existing one, shifting every line after each comment down by one. In files with
many comments (e.g. large SCSS preambles) this shifts all subsequent CSS rules
far enough that the CSS sourcemap — generated before `shimCssText` runs —
points to completely wrong source locations in browser DevTools.

The fix is to drop the `+ '\n'`; internal newlines within a multi-line comment
are still preserved via `_newLinesRe`, and the trailing newline that follows the
comment in `cssText` is already present without any extra injection.
2026-03-20 15:17:31 -07:00
Matthew Beck
9e7ddcaa10 fix(compiler): don't choke on unbalanced parens in declaration block
Following https://github.com/angular/angular/pull/64509 we started
choking on unbalanced closing parentheses in declaration blocks,
specifically in quoted background-image urls. This was reported in
https://github.com/angular/angular/issues/65137.

This occured because we previously (and now again) traverse the entire
declaration block when selecting for :host-context() selectors to shim.
This is an oddity of how we parse styles today, and is likely something
we'd want to remove if we parsed selectors properly.

This change adds a new flag to _splitOnTopLevelCommas which allows it to
continue past unbalanced closing parentheses in the declaration block,
returning _convertColonHostContext to its previous behavior while
keeping support for the extra nesting in :host-context().
2025-11-17 09:46:01 -08:00
Matthew Beck
24cfd5a0ed fix(compiler): support complex selectors in :nth-child()
:nth-child() (and its siblings) support complex expressions, e.g.
`:nth-child(2n of :is(.foo, .bar))`. Previously we'd choke because of
the `:is()`. Now, we reuse the `_parenSuffix` subexpression to match
nested parentheses the same way we do for :host() and :host-context().
Note that we only support 3 levels of nesting, so a selector like
`:nth-child(n of :is(:has(:not(.foo))))` will still break.

I'll say yet again that we really should add a proper parser so we stop
getting bug reports like this :)

Fixes #64913
2025-11-11 14:03:32 -08:00
Matthew Beck
680c3c7bff fix(compiler): support commas in :host() argument
This change adds support for commas in :host() arguments (e.g.
`:host(:not(.foo, .bar))` as well as in nested parens when the argument
is applied without parens (e.g. `:host:not(:has(.foo, .bar))`).
Previously these selectors would receive an extra `[nghost]` attr, e.g.
`[nghost]:not(.foo, [nghost].bar)`.

I didn't file a bug for this one, but it's also blocking on an internal
LSC. Like the other CSS changes, I'll run a TGP to confirm this isn't
breaking.
2025-11-07 10:43:32 -08:00
Matthew Berry
444143758e fix(compiler): support one additional level of nesting in :host()
Previously we supported one level of nested parentheses inside of a
`:host()` selector, e.g. `:host(:not(p))`. This caused a breakage in g3
when I migrated a selector from `:host:not(:has(p))` to
`:host(:not(:has(p)))`. This change adds support for just one more level
of nesting.

It'd be nice to move everything to a real CSS parser (or even update it
to count parentheses like I did with :host-context()), but I wasn't able
to get that to work in ~20 minutes and I'm focusing on other things at
the moment.

This change punts the problem until somebody tries to use just one more
level of nesting in a selector.

Fixes #64830
2025-11-06 10:53:42 -08:00
Matthew Beck
b478e91068 fix(compiler): support arbitrary nesting in :host-context()
Previously we supported one level of nested pseudo-element selectors
inside :host-context(), e.g. :host-context(:is(.foo, .bar)). This was
based on a regex-based approach. We could support deeper levels of
nesting by updating the regex, but using a regex approach prohibits us
from supporting arbitrary nesting.

Rather than just adding one more level to the existing expression, I've
added a new generator function which splits selectors on commas in a
parenthesis-aware way. This allows us to support arbitrary nesting.

It's likely we'll want to reuse this in other places where we're not as
careful today. We'll probably do this on a request-based basis, though.

Fixes #59176
2025-10-27 13:40:47 +01:00
Kristiyan Kostadinov
98f820737b fix(compiler): handle :host-context with comma-separated child selector (#59276)
Both `:host` and `:host-context` work by looking for a specific character sequence that is terminated by `,` or `{` and replacing selectors inside of it with scoped versions. This is implemented as a regex which isn't aware of things like nested selectors. Normally this is fine for `:host`, because each `:host` produces one scoped selector which doesn't affect any child selectors, however it breaks down with `:host-context` which replaces each instance with two selectors. For example, if we have a selector in the form of `:host-context(.foo) a:not(.a, .b)`, the compiler ends up determining that `.a,` is the end selector and produces `.foo[a-host] a[contenta]:not(.a, .foo [a-host] a[contenta]:not(.a, .b) {}`.

These changes resolve the issue by splitting the CSS alogn top-level commas, processing the `:host-context` in them individually, and stiching the CSS back together.

PR Close #59276
2025-01-21 09:11:16 -08:00
hawkgs
b9155b5121 docs: set syntax highlighting to the remaining Markdown code examples blocks (#59088)
There are some code blocks that slipped through the initial Regex-es.

Related to #59026

PR Close #59088
2025-01-14 15:14:02 -05:00
Georgy Serga
549a00d18b fix(compiler): fix multiline selectors (#58681)
multiline selectors where not correctly recognized by the regexp, fix it to fetch newlines as well

Fixes #58399

PR Close #58681
2024-11-15 11:30:27 +01:00
Georgy Serga
58a84b2f79 fix(compiler): resolve :host:host-context(.foo) (#58681)
fix results which had to parse several `-shadowcsshost-no-combinator` occurrences in a single selector

PR Close #58681
2024-11-15 11:30:27 +01:00
Georgy Serga
9587437e60 fix(compiler): transform chained pseudo-selectors (#58681)
fix transformation logic for `:where` and `:is` pseudo-selectors
when these selectors were used in a chain. results were often broken,
the last letter of the selector was incorrectly trimmed.
see tests for examples

Fixes #58226

PR Close #58681
2024-11-15 11:30:27 +01:00
Georgy Serga
70e800ecec fix(compiler): fix :host parsing in pseudo-selectors (#58681)
fix several use-cases where `:host` was used in or around pseudo-selectors
- `:host` followed by a comma inside pseudo-selectors
- `:host` outside of pseudo-selectors when another `:host` is present within
see tests for examples

PR Close #58681
2024-11-15 11:30:27 +01:00
Georgy Serga
46a6324c82 fix(compiler): scope :host-context inside pseudo selectors, do not decrease specificity (#57796)
parse constructions like `:where(:host-context(.foo))` correctly
revert logic which lead to decreased specificity if `:where` was applied
to another selector, for example `div` is transformed to `div[contenta]`
with specificity of (0,1,1) so `div:where(.foo)` should not decrease it
leading to `div[contenta]:where(.foo)` with the same specificity (0,1,1)
instead of `div:where(.foo[contenta])` with specificity equal to (0,0,1)

PR Close #57796
2024-10-10 08:13:22 +00:00
Georgy Serga
69529d8873 fix(compiler): fix parsing of the :host-context with pseudo selectors (#57796)
fix regexp which is used to test for host inside pseudo selectors

PR Close #57796
2024-10-10 08:13:22 +00:00
Georgy Serga
2374b87b64 fix(compiler): preserve attributes attached to :host selector (#57796)
keep attributes used to scope :host selectors

PR Close #57796
2024-10-10 08:13:22 +00:00
Georgy Serga
e8d1944999 fix(compiler): add multiple :host and nested selectors support (#57796)
add support for nested and deeply nested (up to three levels) selectors,
parse multiple :host selectors, scope selectors within pseudo functions

PR Close #57796
2024-10-10 08:13:22 +00:00
Georgy Serga
292ea4714f fix(compiler): fix comment typo (#57796)
fix spelling in the comment

PR Close #57796
2024-10-10 08:13:22 +00:00
Georgy Serga
82144b6d63 fix(compiler): allow combinators inside pseudo selectors (#57796)
allow css combinators within pseudo selector functions, parsing those
correctly. Similarly to previous version, don't break selectors
into part if combinators are within parenthesis, for example
`:where(.one > .two)`

PR Close #57796
2024-10-10 08:13:22 +00:00
Georgy Serga
bc5f1175e9 fix(compiler): transform pseudo selectors correctly for the encapsulated view (#57796)
fix scoping and transforming logic of the `shimCssText` for the
components with encapsulated view:
- add support for pseudo selector functions
- apply content scoping for inner selectors of `:is()` and `:where()`
- allow multiple comma separated selectors inside pseudo selectors

Fixes #45686

PR Close #57796
2024-10-10 08:13:21 +00:00
Joey Perrott
9dbe6fc18b refactor: update license text to point to angular.dev (#57901)
Update license text to point to angular.dev instead of angular.io

PR Close #57901
2024-09-24 15:33:00 +02:00
Daniel Puckowski
387e1cbf89 fix(compiler): fix CSS animation rule scope (#56800)
It is valid CSS to list keyframe names in an animation declaration only
separating the names with a comma and no whitespace. This is typical of
production builds. Updated a couple of regexes and added a couple of
tests to account for this scenario.

Fixes #53038

PR Close #56800
2024-07-09 09:44:50 +02:00
Alan Agius
3e1d6e9d6e fix(compiler): maintain multiline CSS selectors during CSS scoping (#55509)
Previously, multiline selectors were being converted into single lines, resulting in sourcemap disruptions due to shifts in line numbers.

Closes #55508

PR Close #55509
2024-05-06 12:39:50 -07:00
Joey Perrott
8f69c83b84 refactor: migrate compiler to prettier formatting (#55398)
Migrate formatting to prettier for compiler from clang-format

PR Close #55398
2024-04-18 14:18:08 -07:00
Andrea Canciani
f3b624553a refactor: fix a number of typos throughout the codebase (#55018)
Fix some typos detected using spellchecking tools, both in
documentation and in code (comments, identifiers).

PR Close #55018
2024-03-27 10:54:31 -07:00
Daniel Puckowski
66e940aebf feat(compiler): scope selectors in @starting-style (#53943)
make sure selectors inside @starting-style queries are correctly scoped

PR Close #53943
2024-01-17 09:14:11 -08:00
Matthieu Riegler
0198d21231 fix(compiler): apply style on :host attributes in prod builds. (#49118)
In prod builds, selectors are optimized and spaces a removed. #48558 introduced a regression on selectors without spaces. This commit fixes tihs.

Fixes #49100

PR Close #49118
2023-10-11 11:32:19 -07:00
Daniel Puckowski
c27a1e61d6 feat(compiler): scope selectors in @scope queries (#50747)
make sure selectors inside @scope queries are correctly scoped

PR Close #50747
2023-07-11 08:29:53 -07:00
Alan Agius
540e643347 fix(compiler): do not remove comments in component styles (#50346)
Prior to this commit, comments in CSS were being removed. This caused inline sourcemaps to break to the shift in lines.

This caused sourcemaps to break in the ESBuild based builder as this always adds comments at the top of the file with the filename.

Example
```css
 /* src/app/app.component.scss */
* {
  color: red;
  background: transparent;
}
/*# sourceMappingURL=data:application/json;charset=utf-8;base64,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 */
```

Closes #50308

PR Close #50346
2023-06-01 08:45:11 -07:00
Matthieu Riegler
c2bcf0b475 refactor(compiler): Remove strictStyling option for ShadowCss (#48824)
`strictStyling` was an option provided by Polymer but it's not needed by Angular. This commit removes the dead code and updates related comments.

PR Close #48824
2023-02-02 13:38:38 -08:00
Matthieu Riegler
bc8cfa2552 fix(compiler): handle css selectors with space after an escaped character. (#48558)
In Css, selectors with escaped characters require a space after if the following character is a hex character. ie: .\fc ber which matches class="über"
These escaped selectors happen for example when esbuild run with `optimization.minify`

fixes #48524

PR Close #48558
2023-01-24 17:46:33 +00:00
dario-piotrowicz
4c023956d8 fix(compiler): make sure selectors inside container queries are correctly scoped (#48353)
improve the emulated shadowDom implementation so that it can correctly
scope selectors present inside the @container at-rule (recently added
to the css specs)

resolves #48264

PR Close #48353
2022-12-06 09:58:59 -08:00
dario-piotrowicz
051f75648d fix(compiler): scope css keyframes in emulated view encapsulation (#42608)
Ensure that keyframes rules, defined within components with emulated
view encapsulation, are scoped to avoid collisions with keyframes in
other components.

This is achieved by renaming these keyframes to add a prefix that makes
them unique across the application.

In order to enable the handling of keyframes names defined as strings
the previous strategy of replacing quoted css content with `%QUOTED%`
(introduced in commit 7f689a2) has been removed and in its place now
only specific characters inside quotes are being replaced with
placeholder text (those are `;`, `:` and `,`, more can be added in
the future if the need arises).

Closes #33885

BREAKING CHANGE:

Keyframes names are now prefixed with the component's "scope name".
For example, the following keyframes rule in a component definition,
whose "scope name" is host-my-cmp:

   @keyframes foo { ... }

will become:

   @keyframes host-my-cmp_foo { ... }

Any TypeScript/JavaScript code which relied on the names of keyframes rules
will no longer match.

The recommended solutions in this case are to either:
- change the component's view encapsulation to the `None` or `ShadowDom`
- define keyframes rules in global stylesheets (e.g styles.css)
- define keyframes rules programmatically in code.

PR Close #42608
2022-09-29 15:49:51 -07:00
Jan Kuehle
ce76103e8f refactor(compiler): /a/.exec() returns RegExpExecArray (#47169)
Fix compilation issue with TypeScript nightly. TypeScript added a field
`0` to `RegExpMatchArray` in
3b80ddca21.
Before that, `RegExpMatchArray` and `RegExpExecArray` were identical.

In one place Angular incorrectly expects `RegExpMatchArray` as the
result of a RegExp#exec() call. This assignment fails on TypeScript
nightly with the error:

    Property '0' is missing in type 'RegExpExecArray' but required in type 'RegExpMatchArray'.

Fix the issue by using the type `RegExpExecArray` instead. This also
works for older TypeScript versions.

PR Close #47169
2022-08-18 12:22:44 -07:00
Dylan Hunn
58e8f4b708 Revert "fix(compiler): scope css keyframes in emulated view encapsulation (#42608)" (#45786)
This reverts commit 4d6a1d6722.

PR Close #45786
2022-04-27 15:00:41 -07:00
dario-piotrowicz
4d6a1d6722 fix(compiler): scope css keyframes in emulated view encapsulation (#42608)
Ensure that keyframes rules, defined within components with emulated
view encapsulation, are scoped to avoid collisions with keyframes in
other components.

This is achieved by renaming these keyframes to add a prefix that makes
them unique across the application.

In order to enable the handling of keyframes names defined as strings
the previous strategy of replacing quoted css content with `%QUOTED%`
(introduced in commit 7f689a2) has been removed and in its place now
only specific characters inside quotes are being replaced with
placeholder text (those are `;`, `:` and `,`, more can be added in
the future if the need arises).

Closes #33885

BREAKING CHANGE:

Keyframes names are now prefixed with the component's "scope name".
For example, the following keyframes rule in a component definition,
whose "scope name" is host-my-cmp:

   @keyframes foo { ... }

will become:

   @keyframes host-my-cmp_foo { ... }

Any TypeScript/JavaScript code which relied on the names of keyframes rules
will no longer match.

The recommended solutions in this case are to either:
- change the component's view encapsulation to the `None` or `ShadowDom`
- define keyframes rules in global stylesheets (e.g styles.css)
- define keyframes rules programmatically in code.

PR Close #42608
2022-04-27 10:27:17 -07:00
Dylan Hunn
801d11dd8a Revert "fix(compiler): scope css keyframes in emulated view encapsulation (#42608)" (#45466)
This reverts commit f03e313f24.

PR Close #45466
2022-03-29 09:12:19 -07:00
dario-piotrowicz
f03e313f24 fix(compiler): scope css keyframes in emulated view encapsulation (#42608)
Ensure that keyframes rules, defined within components with emulated
view encapsulation, are scoped to avoid collisions with keyframes in
other components.

This is achieved by renaming these keyframes to add a prefix that makes
them unique across the application.

In order to enable the handling of keyframes names defined as strings
the previous strategy of replacing quoted css content with `%QUOTED%`
(introduced in commit 7f689a2) has been removed and in its place now
only specific characters inside quotes are being replaced with
placeholder text (those are `;`, `:` and `,`, more can be added in
the future if the need arises).

Closes #33885

BREAKING CHANGE:

Keyframes names are now prefixed with the component's "scope name".
For example, the following keyframes rule in a component definition,
whose "scope name" is host-my-cmp:

   @keyframes foo { ... }

will become:

   @keyframes host-my-cmp_foo { ... }

Any TypeScript/JavaScript code which relied on the names of keyframes rules
will no longer match.

The recommended solutions in this case are to either:
- change the component's view encapsulation to the `None` or `ShadowDom`
- define keyframes rules in global stylesheets (e.g styles.css)
- define keyframes rules programmatically in code.

PR Close #42608
2022-03-28 17:12:25 -07:00
JoostK
fffa023803 fix(compiler): scope css rules within @layer blocks (#45396)
This commit starts scoping CSS rules nested within `@layer` blocks.

Fixes #45389

PR Close #45396
2022-03-21 14:51:45 -07:00
George Kalpakas
2292a9cbd9 refactor(compiler): improve regular expression for stripping comments (#43456)
Previously, the regular expression used by the compiler's ShadowDOM CSS
shim to strip comments from CSS text was susceptible to [catastrophic
backtracking][1], which could lead to exponential (O(2^n)) increase in
complexity/execution time. More specifically, this would be triggered if
the processed text contained an unterminated comment with lots of
leading whitespace (i.e. `/*`, followed by lots of whitespace characters
and no closing `*/`).

Although such input is unlikely in real-world scenarios, this commit
improves the regular expression to not be susceptible to this issue.

[1]: https://www.regular-expressions.info/catastrophic.html

PR Close #43456
2021-09-16 16:50:49 +00:00
Alex Rickabaugh
d8183c94d4 refactor(compiler): remove unnecessary escapes (#42990)
This commit is part of a larger scale change to eliminate unnecessary
escapes in string literals, in advance of enabling stricter checks in
`ts_library` rules in g3.

PR Close #42990
2021-07-30 09:28:46 -07:00
Kristiyan Kostadinov
abcd4bbfaa fix(compiler): preserve @page rules in encapsulated styles (#41915)
Currently the compiler treats `@page` rules in the same way as `@media`, however that is incorrect and it results in invalid CSS, because `@page` allows style declarations at the root (e.g. `@page (margin: 50%) {}`) and it only allows a limited set of at-rules to be nested into it. Given these restrictions, we can't really encapsulate the styles since they apply at the document level when the user tries to print.

These changes make it so that `@page` rules are preserved so that we don't break the user's CSS.

More information: https://www.w3.org/TR/css-page-3

Fixes #26269.

PR Close #41915
2021-05-06 09:33:56 -04:00
Pete Bacon Darwin
da6ed1562e fix(compiler): strip scoped selectors from @font-face rules (#41815)
`@font-face` rules cannot contain nested selectors. Nor can they be
nested under a selector. Normally this would be a syntax error by the
author of the styles. But in some rare cases, such as importing styles
from a library, and applying `:host ::ng-deep` to the imported styles,
we can end up with broken css if the imported styles happen to contain
`@font-face` rules.

This commit works around this problem by sanitizing such cases (erasing
any scoping selectors) during emulated ShadowDOM encapsulation style
processing.

Fixes #41751

PR Close #41815
2021-04-27 09:12:28 -07:00
Pete Bacon Darwin
aa039a13f0 fix(compiler): correctly process multiple rules containing :host selectors (#41261)
When there was more than one rule in a single style string, only the first
rule was having its `:host` selector processed correctly. Now subsequent
rules will also be processed accurately.

Fixes #41237

PR Close #41261
2021-03-19 12:38:15 -07:00
Pete Bacon Darwin
645c2ef973 fix(compiler): support multiple selectors in :host-context() (#40494)
The previous commits refactored the `ShadowCss` emulator to support
desirable use-cases of `:host-context()`, but it dropped support
for passing a comma separated list of selectors to the `:host-context()` .

This commit rectifies that omission, despite the use-case not being
valid according to the ShadowDOM spec, to ensure backward compatibility
with the previous implementation.

PR Close #40494
2021-02-16 08:41:19 -08:00
Pete Bacon Darwin
679c3bf7ea fix(compiler): handle :host-context and :host in the same selector (#40494)
In `ViewEncapsulation.Emulated` mode the compiler converts `:host` and
`:host-context` pseudo classes into new CSS selectors.

Previously, when there was both `:host-context` and `:host` classes in a
selector, the compiler was generating incorrect selectors. There are two
scenarios:

* Both classes are on the same element (i.e. not separated). E.g.
  `:host-context(.foo):host(.bar)`. This setup should only match the
  host element if it has both `foo` and `bar` classes. So the generated
  CSS selector should be: `.foo.bar<hostmarker>`.
* The `:host` class is on a descendant of the `:host-context`. E.g.
  `:host-context(.foo) :host(.bar)`. This setup should only match the
  `.foo` selector if it is a proper ancestor of the host (and not on the
  host itself). So the generated CSS selector should be:
  `.foo .bar<hostmarker>`.

This commit fixes the generation to handle these scenarios.

Fixes #14349

PR Close #40494
2021-02-16 08:41:19 -08:00