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

pub mod csharp;
pub mod dart;
pub mod go;
pub mod java;
pub mod js;
pub mod python;
pub mod rust;
pub mod swift;

pub use self::csharp::Csharp;
pub use self::dart::Dart;
pub use self::go::Go;
pub use self::java::Java;
pub use self::js::JavaScript;
pub use self::python::Python;
pub use self::rust::Rust;
pub use self::swift::Swift;

use crate::fmt;
use crate::Tokens;
use std::any::Any;
use std::rc::Rc;

/// Trait to implement for language specialization.
pub trait Lang
where
    Self: 'static + Sized,
{
    /// Configuration associated with building a formatting element.
    type Config;
    /// State being used during formatting.
    type Format: Default;
    /// The type used when resolving imports.
    type Import: ?Sized;

    /// The default indentation for the current language.
    fn default_indentation() -> usize {
        4
    }

    /// Performing quoting according to convention set by custom element.
    fn quote_string(out: &mut fmt::Formatter<'_>, input: &str) -> fmt::Result {
        out.write_str(input)
    }

    /// Write a file according to convention by custom element.
    fn format_file(
        tokens: &Tokens<Self>,
        out: &mut fmt::Formatter<'_>,
        config: &Self::Config,
    ) -> fmt::Result {
        let format = Self::Format::default();
        tokens.format(out, config, &format)
    }
}

/// Dummy implementation for unit.
impl Lang for () {
    type Config = ();
    type Format = ();
    type Import = ();
}

/// A type-erased holder for language-specific items.
///
/// Carries formatting and coercion functions like
/// [as_import][LangItem::as_import] to allow language specific processing to
/// work.
pub trait LangItem<L>
where
    Self: Any,
    L: Lang,
{
    /// Format the language item appropriately.
    fn format(
        &self,
        out: &mut fmt::Formatter<'_>,
        config: &L::Config,
        format: &L::Format,
    ) -> fmt::Result;

    /// Check equality.
    fn eq(&self, other: &dyn LangItem<L>) -> bool;

    /// Convert into any type.
    fn as_any(&self) -> &dyn Any;

    /// Coerce into an imported type.
    ///
    /// This is used for import resolution for custom language items.
    fn as_import(&self) -> Option<&L::Import> {
        None
    }
}

/// A box containing a lang item.
pub struct LangBox<L> {
    inner: Rc<dyn LangItem<L>>,
}

impl<L> Clone for LangBox<L>
where
    L: Lang,
{
    fn clone(&self) -> Self {
        Self {
            inner: self.inner.clone(),
        }
    }
}

impl<L> std::fmt::Debug for LangBox<L>
where
    L: Lang,
{
    fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> fmt::Result {
        write!(fmt, "LangBox")
    }
}

impl<L> LangItem<L> for LangBox<L>
where
    L: Lang,
{
    fn format(
        &self,
        out: &mut fmt::Formatter<'_>,
        config: &L::Config,
        format: &L::Format,
    ) -> fmt::Result {
        self.inner.format(out, config, format)
    }

    fn eq(&self, other: &dyn LangItem<L>) -> bool {
        self.inner.eq(other)
    }

    fn as_any(&self) -> &dyn Any {
        self.inner.as_any()
    }

    fn as_import(&self) -> Option<&L::Import> {
        self.inner.as_import()
    }
}

impl<L> From<Rc<dyn LangItem<L>>> for LangBox<L>
where
    L: Lang,
{
    fn from(value: Rc<dyn LangItem<L>>) -> Self {
        Self { inner: value }
    }
}