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
151
152
153
154
155
156
157
158
159
160
161
162
163

use crate::bound::{self, Bound};
use crate::date::{self, Date};
use crate::error::{Error, Result};
use crate::iter::{self, Iter};
use crate::release::{self, Release};
use crate::token;
use crate::version::{Channel, Version};
use proc_macro::{Ident, Span, TokenTree};

pub enum Expr {
    Stable,
    Beta,
    Nightly,
    Date(Date),
    Since(Bound),
    Before(Bound),
    Release(Release),
    Not(Box<Expr>),
    Any(Vec<Expr>),
    All(Vec<Expr>),
}

impl Expr {
    pub fn eval(&self, rustc: Version) -> bool {
        use self::Expr::*;

        match self {
            Stable => rustc.channel == Channel::Stable,
            Beta => rustc.channel == Channel::Beta,
            Nightly => match rustc.channel {
                Channel::Nightly(_) | Channel::Dev => true,
                Channel::Stable | Channel::Beta => false,
            },
            Date(date) => match rustc.channel {
                Channel::Nightly(rustc) => rustc == *date,
                Channel::Stable | Channel::Beta | Channel::Dev => false,
            },
            Since(bound) => rustc >= *bound,
            Before(bound) => rustc < *bound,
            Release(release) => {
                rustc.channel == Channel::Stable
                    && rustc.minor == release.minor
                    && release.patch.map_or(true, |patch| rustc.patch == patch)
            }
            Not(expr) => !expr.eval(rustc),
            Any(exprs) => exprs.iter().any(|e| e.eval(rustc)),
            All(exprs) => exprs.iter().all(|e| e.eval(rustc)),
        }
    }
}

pub fn parse(iter: Iter) -> Result<Expr> {
    match &iter.next() {
        Some(TokenTree::Ident(i)) if i.to_string() == "stable" => parse_stable(iter),
        Some(TokenTree::Ident(i)) if i.to_string() == "beta" => Ok(Expr::Beta),
        Some(TokenTree::Ident(i)) if i.to_string() == "nightly" => parse_nightly(iter),
        Some(TokenTree::Ident(i)) if i.to_string() == "since" => parse_since(i, iter),
        Some(TokenTree::Ident(i)) if i.to_string() == "before" => parse_before(i, iter),
        Some(TokenTree::Ident(i)) if i.to_string() == "not" => parse_not(i, iter),
        Some(TokenTree::Ident(i)) if i.to_string() == "any" => parse_any(i, iter),
        Some(TokenTree::Ident(i)) if i.to_string() == "all" => parse_all(i, iter),
        unexpected => {
            let span = unexpected
                .as_ref()
                .map_or_else(Span::call_site, TokenTree::span);
            Err(Error::new(span, "expected one of `stable`, `beta`, `nightly`, `since`, `before`, `not`, `any`, `all`"))
        }
    }
}

fn parse_nightly(iter: Iter) -> Result<Expr> {
    let paren = match token::parse_optional_paren(iter) {
        Some(group) => group,
        None => return Ok(Expr::Nightly),
    };

    let ref mut inner = iter::new(paren.stream());
    let date = date::parse(paren, inner)?;
    token::parse_optional_punct(inner, ',');
    token::parse_end(inner)?;

    Ok(Expr::Date(date))
}

fn parse_stable(iter: Iter) -> Result<Expr> {
    let paren = match token::parse_optional_paren(iter) {
        Some(group) => group,
        None => return Ok(Expr::Stable),
    };

    let ref mut inner = iter::new(paren.stream());
    let release = release::parse(paren, inner)?;
    token::parse_optional_punct(inner, ',');
    token::parse_end(inner)?;

    Ok(Expr::Release(release))
}

fn parse_since(introducer: &Ident, iter: Iter) -> Result<Expr> {
    let paren = token::parse_paren(introducer, iter)?;

    let ref mut inner = iter::new(paren.stream());
    let bound = bound::parse(paren, inner)?;
    token::parse_optional_punct(inner, ',');
    token::parse_end(inner)?;

    Ok(Expr::Since(bound))
}

fn parse_before(introducer: &Ident, iter: Iter) -> Result<Expr> {
    let paren = token::parse_paren(introducer, iter)?;

    let ref mut inner = iter::new(paren.stream());
    let bound = bound::parse(paren, inner)?;
    token::parse_optional_punct(inner, ',');
    token::parse_end(inner)?;

    Ok(Expr::Before(bound))
}

fn parse_not(introducer: &Ident, iter: Iter) -> Result<Expr> {
    let paren = token::parse_paren(introducer, iter)?;

    let ref mut inner = iter::new(paren.stream());
    let expr = self::parse(inner)?;
    token::parse_optional_punct(inner, ',');
    token::parse_end(inner)?;

    Ok(Expr::Not(Box::new(expr)))
}

fn parse_any(introducer: &Ident, iter: Iter) -> Result<Expr> {
    let paren = token::parse_paren(introducer, iter)?;

    let ref mut inner = iter::new(paren.stream());
    let exprs = parse_comma_separated(inner)?;

    Ok(Expr::Any(exprs.into_iter().collect()))
}

fn parse_all(introducer: &Ident, iter: Iter) -> Result<Expr> {
    let paren = token::parse_paren(introducer, iter)?;

    let ref mut inner = iter::new(paren.stream());
    let exprs = parse_comma_separated(inner)?;

    Ok(Expr::All(exprs.into_iter().collect()))
}

fn parse_comma_separated(iter: Iter) -> Result<Vec<Expr>> {
    let mut exprs = Vec::new();

    while iter.peek().is_some() {
        let expr = self::parse(iter)?;
        exprs.push(expr);
        if iter.peek().is_none() {
            break;
        }
        token::parse_punct(iter, ',')?;
    }

    Ok(exprs)
}