fix(compiler): handle :host-context with comma-separated child selector #59276
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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. 
angular-robot bot added the area: compiler 
crisbeto added the action: global presubmit 
| Passing TGP, aside from some unrelated broken targets. |
crisbeto added action: review 
| // cc @mattrberry |
| This makes me want to remove support for |
devversion approved these changes Jan 21, 2025
| const _parenSuffix = '(?:\\((' + '(?:\\([^)(]*\\)|[^)(]*)+?' + ')\\))'; | ||
| const _cssColonHostRe = new RegExp(_polyfillHost + _parenSuffix + '?([^,{]*)', 'gim'); | ||
| // note: :host-context patterns are terminated with `{`, as opposed to :host which | ||
| // is both `{` and `,` because :host-context handles top-level commas differently. |
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OOC: do you have any information on this?
crisbeto added action: merge | This PR was merged into the repository by commit 98f8207. The changes were merged into the following branches: main, 19.1.x |
AndrewKushnir pushed a commit that referenced this pull request Jan 21, 2025
…or (#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
PrajaktaB27 pushed a commit to PrajaktaB27/angular that referenced this pull request Feb 7, 2025
…or (angular#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 angular#59276
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Both
:hostand:host-contextwork 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:hostproduces one scoped selector which doesn't affect any child selectors, however it breaks down with:host-contextwhich 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-contextin them individually, and stiching the CSS back together.