mirror of https://github.com/stelzo/typst.git
63 lines
1.5 KiB
Rust
63 lines
1.5 KiB
Rust
//! Unicode identifiers.
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use std::ops::Deref;
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use unicode_xid::UnicodeXID;
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/// An identifier as defined by unicode with a few extra permissible characters.
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///
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/// This is defined as in the [Unicode Standard], but allows additionally
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/// `-` and `_` as starting and continuing characters.
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///
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/// [Unicode Standard]: http://www.unicode.org/reports/tr31/
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#[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd)]
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pub struct Ident(pub String);
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impl Ident {
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/// Create a new identifier from a string checking that it is a valid.
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pub fn new(ident: impl AsRef<str> + Into<String>) -> Option<Self> {
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if is_ident(ident.as_ref()) {
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Some(Self(ident.into()))
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} else {
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None
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}
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}
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/// Return a reference to the underlying string.
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pub fn as_str(&self) -> &str {
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self
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}
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}
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impl AsRef<str> for Ident {
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fn as_ref(&self) -> &str {
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self
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}
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}
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impl Deref for Ident {
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type Target = str;
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fn deref(&self) -> &Self::Target {
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self.0.as_str()
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}
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}
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/// Whether the string is a valid identifier.
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pub fn is_ident(string: &str) -> bool {
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let mut chars = string.chars();
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chars
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.next()
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.map_or(false, |c| is_id_start(c) && chars.all(is_id_continue))
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}
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/// Whether the character can start an identifier.
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pub fn is_id_start(c: char) -> bool {
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c.is_xid_start() || c == '_'
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}
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/// Whether the character can continue an identifier.
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pub fn is_id_continue(c: char) -> bool {
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c.is_xid_continue() || c == '_' || c == '-'
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}
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