81 lines
3.1 KiB
Rust
81 lines
3.1 KiB
Rust
/// <https://infra.spec.whatwg.org/#ascii-alpha>
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pub fn is_ascii_alpha(c: char) -> bool {
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c.is_ascii_alphabetic()
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}
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/// <https://infra.spec.whatwg.org/#ascii-alphanumeric>
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pub fn is_ascii_alphanumeric(c: char) -> bool {
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c.is_ascii_alphanumeric()
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}
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/// <https://html.spec.whatwg.org/multipage/syntax.html#syntax-tag-name>
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///
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/// The rules around what is a valid tag name are complicated. The standard
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/// doesn't give an easy answer. Because of this, we're conservative in what we
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/// allow. This way, the output we produce should parse correctly in a wide
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/// range of circumstances while following the standard.
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///
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/// The `annotation-xml` MathML element requires us to allow dashes in tag
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/// names.
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pub fn is_valid_tag_name(name: &str) -> bool {
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!name.is_empty()
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&& name.chars().take(1).all(is_ascii_alpha)
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&& name.chars().all(|c| is_ascii_alphanumeric(c) || c == '-')
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}
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/// <https://html.spec.whatwg.org/multipage/syntax.html#syntax-attribute-name>
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///
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/// The rules around what is a valid attribute name are complicated. The
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/// standard doesn't give an easy answer. Because of this, we're conservative in
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/// what we allow. This way, the output we produce should parse correctly in a
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/// wide range of circumstances while following the standard.
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pub fn is_valid_attribute_name(name: &str) -> bool {
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!name.is_empty()
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&& name.chars().take(1).all(is_ascii_alpha)
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&& name
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.chars()
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.all(|c| is_ascii_alphanumeric(c) || c == '-' || c == '_')
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}
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/// https://html.spec.whatwg.org/multipage/syntax.html#cdata-rcdata-restrictions
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///
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/// The tag name must be ascii-only.
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pub fn is_valid_raw_text(tag_name: &str, text: &str) -> bool {
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// In case we ever decide to relax tag name ascii requirements.
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assert!(tag_name.is_ascii());
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// "The text in raw text and escapable raw text elements must not contain
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// any occurrences of the string "</" (U+003C LESS-THAN SIGN, U+002F
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// SOLIDUS) [...]"
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for (i, _) in text.match_indices("</") {
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let start = i + "</".len();
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let potential_tag_name = text[start..]
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.chars()
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.take(tag_name.chars().count())
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.collect::<String>();
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// "[...] followed by characters that case-insensitively match the tag
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// name of the element [...]"
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//
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// Note: Since we know that tag names are ascii-only, we can convert
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// both to lowercase for a case-insensitive comparison without weird
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// unicode shenanigans.
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if potential_tag_name.to_ascii_lowercase() != tag_name.to_ascii_lowercase() {
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continue;
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}
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// "[...] followed by [...]"
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let Some(trailing) = text[start + potential_tag_name.len()..].chars().next() else {
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continue;
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};
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// "[...] one of U+0009 CHARACTER TABULATION (tab), U+000A LINE FEED
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// (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), U+0020
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// SPACE, U+003E GREATER-THAN SIGN (>), or U+002F SOLIDUS (/)."
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if matches!(trailing, '\t' | '\n' | '\x0C' | '\r' | ' ' | '>' | '/') {
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return false;
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}
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}
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true
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}
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