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
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179

use super::Tokens;

use std::borrow::Cow;

use proc_macro2::{Group, Literal, Op, Span, Term, TokenStream, TokenTree};

/// Types that can be interpolated inside a [`quote!`] invocation.
///
/// [`quote!`]: macro.quote.html
pub trait ToTokens {
    /// Write `self` to the given `Tokens`.
    ///
    /// Example implementation for a struct representing Rust paths like
    /// `std::cmp::PartialEq`:
    ///
    /// ```
    /// extern crate quote;
    /// use quote::{Tokens, ToTokens};
    ///
    /// extern crate proc_macro2;
    /// use proc_macro2::{TokenTree, Spacing, Span, Op};
    ///
    /// pub struct Path {
    ///     pub global: bool,
    ///     pub segments: Vec<PathSegment>,
    /// }
    ///
    /// impl ToTokens for Path {
    ///     fn to_tokens(&self, tokens: &mut Tokens) {
    ///         for (i, segment) in self.segments.iter().enumerate() {
    ///             if i > 0 || self.global {
    ///                 // Double colon `::`
    ///                 tokens.append(Op::new(':', Spacing::Joint));
    ///                 tokens.append(Op::new(':', Spacing::Alone));
    ///             }
    ///             segment.to_tokens(tokens);
    ///         }
    ///     }
    /// }
    /// #
    /// # pub struct PathSegment;
    /// #
    /// # impl ToTokens for PathSegment {
    /// #     fn to_tokens(&self, tokens: &mut Tokens) {
    /// #         unimplemented!()
    /// #     }
    /// # }
    /// #
    /// # fn main() {}
    /// ```
    fn to_tokens(&self, tokens: &mut Tokens);

    /// Convert `self` directly into a `Tokens` object.
    ///
    /// This method is implicitly implemented using `to_tokens`, and acts as a
    /// convenience method for consumers of the `ToTokens` trait.
    fn into_tokens(self) -> Tokens
    where
        Self: Sized,
    {
        let mut tokens = Tokens::new();
        self.to_tokens(&mut tokens);
        tokens
    }
}

impl<'a, T: ?Sized + ToTokens> ToTokens for &'a T {
    fn to_tokens(&self, tokens: &mut Tokens) {
        (**self).to_tokens(tokens);
    }
}

impl<'a, T: ?Sized + ToOwned + ToTokens> ToTokens for Cow<'a, T> {
    fn to_tokens(&self, tokens: &mut Tokens) {
        (**self).to_tokens(tokens);
    }
}

impl<T: ?Sized + ToTokens> ToTokens for Box<T> {
    fn to_tokens(&self, tokens: &mut Tokens) {
        (**self).to_tokens(tokens);
    }
}

impl<T: ToTokens> ToTokens for Option<T> {
    fn to_tokens(&self, tokens: &mut Tokens) {
        if let Some(ref t) = *self {
            t.to_tokens(tokens);
        }
    }
}

impl ToTokens for str {
    fn to_tokens(&self, tokens: &mut Tokens) {
        tokens.append(Literal::string(self));
    }
}

impl ToTokens for String {
    fn to_tokens(&self, tokens: &mut Tokens) {
        self.as_str().to_tokens(tokens);
    }
}

macro_rules! primitive {
    ($($t:ident => $name:ident)*) => ($(
        impl ToTokens for $t {
            fn to_tokens(&self, tokens: &mut Tokens) {
                tokens.append(Literal::$name(*self));
            }
        }
    )*)
}

primitive! {
    i8 => i8_suffixed
    i16 => i16_suffixed
    i32 => i32_suffixed
    i64 => i64_suffixed
    isize => isize_suffixed

    u8 => u8_suffixed
    u16 => u16_suffixed
    u32 => u32_suffixed
    u64 => u64_suffixed
    usize => usize_suffixed

    f32 => f32_suffixed
    f64 => f64_suffixed
}

impl ToTokens for char {
    fn to_tokens(&self, tokens: &mut Tokens) {
        tokens.append(Literal::character(*self));
    }
}

impl ToTokens for bool {
    fn to_tokens(&self, tokens: &mut Tokens) {
        let word = if *self { "true" } else { "false" };
        tokens.append(Term::new(word, Span::call_site()));
    }
}

impl ToTokens for Group {
    fn to_tokens(&self, tokens: &mut Tokens) {
        tokens.append(self.clone());
    }
}

impl ToTokens for Term {
    fn to_tokens(&self, tokens: &mut Tokens) {
        tokens.append(self.clone());
    }
}

impl ToTokens for Op {
    fn to_tokens(&self, tokens: &mut Tokens) {
        tokens.append(self.clone());
    }
}

impl ToTokens for Literal {
    fn to_tokens(&self, tokens: &mut Tokens) {
        tokens.append(self.clone());
    }
}

impl ToTokens for TokenTree {
    fn to_tokens(&self, dst: &mut Tokens) {
        dst.append(self.clone());
    }
}

impl ToTokens for TokenStream {
    fn to_tokens(&self, dst: &mut Tokens) {
        dst.append_all(self.clone().into_iter());
    }
}