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-rw-r--r--third_party/rust/syn/src/ident.rs101
1 files changed, 101 insertions, 0 deletions
diff --git a/third_party/rust/syn/src/ident.rs b/third_party/rust/syn/src/ident.rs
new file mode 100644
index 0000000000..8e3d8bda97
--- /dev/null
+++ b/third_party/rust/syn/src/ident.rs
@@ -0,0 +1,101 @@
+#[cfg(feature = "parsing")]
+use crate::buffer::Cursor;
+#[cfg(feature = "parsing")]
+use crate::lookahead;
+#[cfg(feature = "parsing")]
+use crate::parse::{Parse, ParseStream, Result};
+#[cfg(feature = "parsing")]
+use crate::token::Token;
+
+pub use proc_macro2::Ident;
+
+#[cfg(feature = "parsing")]
+#[doc(hidden)]
+#[allow(non_snake_case)]
+pub fn Ident(marker: lookahead::TokenMarker) -> Ident {
+ match marker {}
+}
+
+#[cfg(feature = "parsing")]
+fn accept_as_ident(ident: &Ident) -> bool {
+ match ident.to_string().as_str() {
+ "_" |
+ // Based on https://doc.rust-lang.org/grammar.html#keywords
+ // and https://github.com/rust-lang/rfcs/blob/master/text/2421-unreservations-2018.md
+ // and https://github.com/rust-lang/rfcs/blob/master/text/2420-unreserve-proc.md
+ "abstract" | "as" | "become" | "box" | "break" | "const" | "continue" |
+ "crate" | "do" | "else" | "enum" | "extern" | "false" | "final" | "fn" |
+ "for" | "if" | "impl" | "in" | "let" | "loop" | "macro" | "match" |
+ "mod" | "move" | "mut" | "override" | "priv" | "pub" | "ref" |
+ "return" | "Self" | "self" | "static" | "struct" | "super" | "trait" |
+ "true" | "type" | "typeof" | "unsafe" | "unsized" | "use" | "virtual" |
+ "where" | "while" | "yield" => false,
+ _ => true,
+ }
+}
+
+#[cfg(feature = "parsing")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+impl Parse for Ident {
+ fn parse(input: ParseStream) -> Result<Self> {
+ input.step(|cursor| {
+ if let Some((ident, rest)) = cursor.ident() {
+ if accept_as_ident(&ident) {
+ return Ok((ident, rest));
+ }
+ }
+ Err(cursor.error("expected identifier"))
+ })
+ }
+}
+
+#[cfg(feature = "parsing")]
+impl Token for Ident {
+ fn peek(cursor: Cursor) -> bool {
+ if let Some((ident, _rest)) = cursor.ident() {
+ accept_as_ident(&ident)
+ } else {
+ false
+ }
+ }
+
+ fn display() -> &'static str {
+ "identifier"
+ }
+}
+
+macro_rules! ident_from_token {
+ ($token:ident) => {
+ impl From<Token![$token]> for Ident {
+ fn from(token: Token![$token]) -> Ident {
+ Ident::new(stringify!($token), token.span)
+ }
+ }
+ };
+}
+
+ident_from_token!(self);
+ident_from_token!(Self);
+ident_from_token!(super);
+ident_from_token!(crate);
+ident_from_token!(extern);
+
+impl From<Token![_]> for Ident {
+ fn from(token: Token![_]) -> Ident {
+ Ident::new("_", token.span)
+ }
+}
+
+pub fn xid_ok(symbol: &str) -> bool {
+ let mut chars = symbol.chars();
+ let first = chars.next().unwrap();
+ if !(first == '_' || unicode_ident::is_xid_start(first)) {
+ return false;
+ }
+ for ch in chars {
+ if !unicode_ident::is_xid_continue(ch) {
+ return false;
+ }
+ }
+ true
+}