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

mod miette;

#[cfg(feature = "miette")]
use ::miette::LabeledSpan;
use std::cmp;
use std::fmt::{self, Display, Formatter};

#[cfg(feature = "miette")]
pub use crate::diagnostics::miette::diagnose;

/// Location and length of a token within a glob expression.
///
/// Spans are encoded as a tuple of `usize`s, where the first element is the location or position
/// and the second element is the length. Both position and length are measured in bytes and
/// **not** code points, graphemes, etc.
///
/// # Examples
///
/// Spans can be used to isolate sub-expressions.
///
/// ```rust
/// use wax::Glob;
///
/// let expression = "**/*.txt";
/// let glob = Glob::new(expression).unwrap();
/// for token in glob.captures() {
///     let (start, n) = token.span();
///     println!("capturing sub-expression: {}", &expression[start..][..n]);
/// }
/// ```
pub type Span = (usize, usize);

pub trait SpanExt {
    fn union(&self, other: &Self) -> Self;
}

impl SpanExt for Span {
    fn union(&self, other: &Self) -> Self {
        let start = cmp::min(self.0, other.0);
        let end = cmp::max(self.0 + self.1, other.0 + other.1);
        (start, end - start)
    }
}

/// Error associated with a [`Span`] within a glob expression.
///
/// Located errors describe specific instances of an error within a glob expression. Types that
/// implement this trait provide a location within a glob expression via the [`LocatedError::span`]
/// function as well as a description via the [`Display`] trait. See [`BuildError::locations`].
///
/// [`BuildError::locations`]: crate::BuildError::locations
/// [`Display`]: std::fmt::Display
/// [`LocatedError::span`]: crate::LocatedError::span
/// [`Span`]: crate::Span
pub trait LocatedError: Display {
    /// Gets the span within the glob expression with which the error is associated.
    fn span(&self) -> Span;
}

#[derive(Clone, Copy, Debug)]
pub struct CompositeSpan {
    label: &'static str,
    kind: CompositeSpanKind,
}

impl CompositeSpan {
    pub fn spanned(label: &'static str, span: Span) -> Self {
        CompositeSpan {
            label,
            kind: CompositeSpanKind::Span(span),
        }
    }

    pub fn correlated(label: &'static str, span: Span, correlated: CorrelatedSpan) -> Self {
        CompositeSpan {
            label,
            kind: CompositeSpanKind::Correlated { span, correlated },
        }
    }

    #[cfg(feature = "miette")]
    pub fn labels(&self) -> Vec<LabeledSpan> {
        let label = Some(self.label.to_string());
        match self.kind {
            CompositeSpanKind::Span(ref span) => vec![LabeledSpan::new_with_span(label, *span)],
            CompositeSpanKind::Correlated {
                ref span,
                ref correlated,
            } => Some(LabeledSpan::new_with_span(label, *span))
                .into_iter()
                .chain(correlated.labels())
                .collect(),
        }
    }
}

impl Display for CompositeSpan {
    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
        write!(f, "{}", self.label)
    }
}

impl LocatedError for CompositeSpan {
    fn span(&self) -> Span {
        match self.kind {
            CompositeSpanKind::Span(ref span) | CompositeSpanKind::Correlated { ref span, .. } => {
                *span
            },
        }
    }
}

#[derive(Clone, Copy, Debug)]
enum CompositeSpanKind {
    Span(Span),
    Correlated {
        span: Span,
        #[cfg_attr(not(feature = "miette"), allow(dead_code))]
        correlated: CorrelatedSpan,
    },
}

#[derive(Clone, Copy, Debug)]
pub enum CorrelatedSpan {
    Contiguous(Span),
    Split(Span, Span),
}

impl CorrelatedSpan {
    pub fn split_some(left: Option<Span>, right: Span) -> Self {
        if let Some(left) = left {
            CorrelatedSpan::Split(left, right)
        }
        else {
            CorrelatedSpan::Contiguous(right)
        }
    }

    #[cfg(feature = "miette")]
    pub fn labels(&self) -> Vec<LabeledSpan> {
        let label = Some("here".to_string());
        match self {
            CorrelatedSpan::Contiguous(ref span) => {
                vec![LabeledSpan::new_with_span(label, *span)]
            },
            CorrelatedSpan::Split(ref left, ref right) => vec![
                LabeledSpan::new_with_span(label.clone(), *left),
                LabeledSpan::new_with_span(label, *right),
            ],
        }
    }
}

impl From<Span> for CorrelatedSpan {
    fn from(span: Span) -> Self {
        CorrelatedSpan::Contiguous(span)
    }
}