mirror of
https://github.com/typst/typst
synced 2025-07-27 14:27:56 +08:00
82 lines
2.7 KiB
Rust
82 lines
2.7 KiB
Rust
//! Defines syntactical properties of HTML tags, attributes, and text.
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/// Check whether a character is in a tag name.
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pub const fn is_valid_in_tag_name(c: char) -> bool {
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c.is_ascii_alphanumeric()
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}
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/// Check whether a character is valid in an attribute name.
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pub const fn is_valid_in_attribute_name(c: char) -> bool {
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match c {
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// These are forbidden.
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'\0' | ' ' | '"' | '\'' | '>' | '/' | '=' => false,
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c if is_whatwg_control_char(c) => false,
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c if is_whatwg_non_char(c) => false,
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// _Everything_ else is allowed, including U+2029 paragraph
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// separator. Go wild.
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_ => true,
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}
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}
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/// Check whether a character can be an used in an attribute value without
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/// escaping.
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///
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/// See <https://html.spec.whatwg.org/multipage/syntax.html#attributes-2>
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pub const fn is_valid_in_attribute_value(c: char) -> bool {
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match c {
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// Ampersands are sometimes legal (i.e. when they are not _ambiguous
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// ampersands_) but it is not worth the trouble to check for that.
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'&' => false,
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// Quotation marks are not allowed in double-quote-delimited attribute
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// values.
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'"' => false,
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// All other text characters are allowed.
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c => is_w3c_text_char(c),
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}
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}
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/// Check whether a character can be an used in normal text without
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/// escaping.
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pub const fn is_valid_in_normal_element_text(c: char) -> bool {
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match c {
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// Ampersands are sometimes legal (i.e. when they are not _ambiguous
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// ampersands_) but it is not worth the trouble to check for that.
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'&' => false,
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// Less-than signs are not allowed in text.
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'<' => false,
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// All other text characters are allowed.
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c => is_w3c_text_char(c),
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}
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}
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/// Check if something is valid text in HTML.
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pub const fn is_w3c_text_char(c: char) -> bool {
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match c {
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// Non-characters are obviously not text characters.
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c if is_whatwg_non_char(c) => false,
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// Control characters are disallowed, except for whitespace.
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c if is_whatwg_control_char(c) => c.is_ascii_whitespace(),
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// Everything else is allowed.
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_ => true,
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}
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}
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const fn is_whatwg_non_char(c: char) -> bool {
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match c {
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'\u{fdd0}'..='\u{fdef}' => true,
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// Non-characters matching xxFFFE or xxFFFF up to x10FFFF (inclusive).
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c if c as u32 & 0xfffe == 0xfffe && c as u32 <= 0x10ffff => true,
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_ => false,
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}
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}
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const fn is_whatwg_control_char(c: char) -> bool {
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match c {
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// C0 control characters.
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'\u{00}'..='\u{1f}' => true,
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// Other control characters.
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'\u{7f}'..='\u{9f}' => true,
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_ => false,
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}
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}
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