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// Copyright 2018 Syn Developers
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::cmp::Ordering;
use std::fmt::{self, Display};
use std::hash::{Hash, Hasher};
use proc_macro2::{Ident, Span};
use unicode_xid::UnicodeXID;
use token::Apostrophe;
/// A Rust lifetime: `'a`.
///
/// Lifetime names must conform to the following rules:
///
/// - Must start with an apostrophe.
/// - Must not consist of just an apostrophe: `'`.
/// - Character after the apostrophe must be `_` or a Unicode code point with
/// the XID_Start property.
/// - All following characters must be Unicode code points with the XID_Continue
/// property.
///
/// *This type is available if Syn is built with the `"derive"` or `"full"`
/// feature.*
#[cfg_attr(feature = "extra-traits", derive(Debug))]
#[derive(Clone)]
pub struct Lifetime {
pub apostrophe: Apostrophe,
pub ident: Ident,
}
impl Lifetime {
pub fn new(s: &str, span: Span) -> Self {
if !s.starts_with('\'') {
panic!(
"lifetime name must start with apostrophe as in \"'a\", got {:?}",
s
);
}
if s == "'" {
panic!("lifetime name must not be empty");
}
fn xid_ok(s: &str) -> bool {
let mut chars = s.chars();
let first = chars.next().unwrap();
if !(UnicodeXID::is_xid_start(first) || first == '_') {
return false;
}
for ch in chars {
if !UnicodeXID::is_xid_continue(ch) {
return false;
}
}
true
}
if !xid_ok(&s[1..]) {
panic!("{:?} is not a valid lifetime name", s);
}
Lifetime {
apostrophe: Apostrophe::default(),
ident: Ident::new(&s[1..], span),
}
}
}
impl Display for Lifetime {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
"'".fmt(formatter)?;
self.ident.fmt(formatter)
}
}
impl PartialEq for Lifetime {
fn eq(&self, other: &Lifetime) -> bool {
self.ident.eq(&other.ident)
}
}
impl Eq for Lifetime {}
impl PartialOrd for Lifetime {
fn partial_cmp(&self, other: &Lifetime) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl Ord for Lifetime {
fn cmp(&self, other: &Lifetime) -> Ordering {
self.ident.cmp(&other.ident)
}
}
impl Hash for Lifetime {
fn hash<H: Hasher>(&self, h: &mut H) {
self.ident.hash(h)
}
}
#[cfg(feature = "parsing")]
pub mod parsing {
use super::*;
use buffer::Cursor;
use parse_error;
use synom::PResult;
use synom::Synom;
impl Synom for Lifetime {
fn parse(input: Cursor) -> PResult<Self> {
let (apostrophe, rest) = Apostrophe::parse(input)?;
let (ident, rest) = match rest.ident() {
Some(pair) => pair,
None => return parse_error(),
};
let ret = Lifetime {
ident: ident,
apostrophe: apostrophe,
};
Ok((ret, rest))
}
fn description() -> Option<&'static str> {
Some("lifetime")
}
}
}
#[cfg(feature = "printing")]
mod printing {
use super::*;
use proc_macro2::TokenStream;
use quote::ToTokens;
impl ToTokens for Lifetime {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.apostrophe.to_tokens(tokens);
self.ident.to_tokens(tokens);
}
}
}