1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150

// 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);
        }
    }
}