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
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
use std::error::Error as StdError;
use std::fmt::{Display, Formatter, Result};

/// Type representing a TOML parse error
#[derive(Debug, Clone, Eq, PartialEq, Hash)]
pub struct TomlError {
    message: String,
    raw: Option<String>,
    keys: Vec<String>,
    span: Option<std::ops::Range<usize>>,
}

impl TomlError {
    #[cfg(feature = "parse")]
    pub(crate) fn new(
        error: winnow::error::ParseError<
            crate::parser::prelude::Input<'_>,
            winnow::error::ContextError,
        >,
        mut raw: crate::parser::prelude::Input<'_>,
    ) -> Self {
        use winnow::stream::Stream;

        let offset = error.offset();
        let span = if offset == raw.len() {
            offset..offset
        } else {
            offset..(offset + 1)
        };

        let message = error.inner().to_string();
        let raw = raw.finish();

        Self {
            message,
            raw: Some(String::from_utf8(raw.to_owned()).expect("original document was utf8")),
            keys: Vec::new(),
            span: Some(span),
        }
    }

    #[cfg(any(feature = "serde", feature = "parse"))]
    pub(crate) fn custom(message: String, span: Option<std::ops::Range<usize>>) -> Self {
        Self {
            message,
            raw: None,
            keys: Vec::new(),
            span,
        }
    }

    #[cfg(feature = "serde")]
    pub(crate) fn add_key(&mut self, key: String) {
        self.keys.insert(0, key);
    }

    /// What went wrong
    pub fn message(&self) -> &str {
        &self.message
    }

    /// The start/end index into the original document where the error occurred
    pub fn span(&self) -> Option<std::ops::Range<usize>> {
        self.span.clone()
    }

    #[cfg(feature = "serde")]
    pub(crate) fn set_span(&mut self, span: Option<std::ops::Range<usize>>) {
        self.span = span;
    }

    #[cfg(feature = "serde")]
    pub(crate) fn set_raw(&mut self, raw: Option<String>) {
        self.raw = raw;
    }
}

/// Displays a TOML parse error
///
/// # Example
///
/// TOML parse error at line 1, column 10
///   |
/// 1 | 00:32:00.a999999
///   |          ^
/// Unexpected `a`
/// Expected `digit`
/// While parsing a Time
/// While parsing a Date-Time
impl Display for TomlError {
    fn fmt(&self, f: &mut Formatter<'_>) -> Result {
        let mut context = false;
        if let (Some(raw), Some(span)) = (&self.raw, self.span()) {
            context = true;

            let (line, column) = translate_position(raw.as_bytes(), span.start);
            let line_num = line + 1;
            let col_num = column + 1;
            let gutter = line_num.to_string().len();
            let content = raw.split('\n').nth(line).expect("valid line number");
            let highlight_len = span.end - span.start;
            // Allow highlight to go one past the line
            let highlight_len = highlight_len.min(content.len().saturating_sub(column));

            writeln!(
                f,
                "TOML parse error at line {}, column {}",
                line_num, col_num
            )?;
            //   |
            for _ in 0..=gutter {
                write!(f, " ")?;
            }
            writeln!(f, "|")?;

            // 1 | 00:32:00.a999999
            write!(f, "{} | ", line_num)?;
            writeln!(f, "{}", content)?;

            //   |          ^
            for _ in 0..=gutter {
                write!(f, " ")?;
            }
            write!(f, "|")?;
            for _ in 0..=column {
                write!(f, " ")?;
            }
            // The span will be empty at eof, so we need to make sure we always print at least
            // one `^`
            write!(f, "^")?;
            for _ in 1..highlight_len {
                write!(f, "^")?;
            }
            writeln!(f)?;
        }
        writeln!(f, "{}", self.message)?;
        if !context && !self.keys.is_empty() {
            writeln!(f, "in `{}`", self.keys.join("."))?;
        }

        Ok(())
    }
}

impl StdError for TomlError {
    fn description(&self) -> &'static str {
        "TOML parse error"
    }
}

fn translate_position(input: &[u8], index: usize) -> (usize, usize) {
    if input.is_empty() {
        return (0, index);
    }

    let safe_index = index.min(input.len() - 1);
    let column_offset = index - safe_index;
    let index = safe_index;

    let nl = input[0..index]
        .iter()
        .rev()
        .enumerate()
        .find(|(_, b)| **b == b'\n')
        .map(|(nl, _)| index - nl - 1);
    let line_start = match nl {
        Some(nl) => nl + 1,
        None => 0,
    };
    let line = input[0..line_start].iter().filter(|b| **b == b'\n').count();

    let column = std::str::from_utf8(&input[line_start..=index])
        .map(|s| s.chars().count() - 1)
        .unwrap_or_else(|_| index - line_start);
    let column = column + column_offset;

    (line, column)
}

#[cfg(test)]
mod test_translate_position {
    use super::*;

    #[test]
    fn empty() {
        let input = b"";
        let index = 0;
        let position = translate_position(&input[..], index);
        assert_eq!(position, (0, 0));
    }

    #[test]
    fn start() {
        let input = b"Hello";
        let index = 0;
        let position = translate_position(&input[..], index);
        assert_eq!(position, (0, 0));
    }

    #[test]
    fn end() {
        let input = b"Hello";
        let index = input.len() - 1;
        let position = translate_position(&input[..], index);
        assert_eq!(position, (0, input.len() - 1));
    }

    #[test]
    fn after() {
        let input = b"Hello";
        let index = input.len();
        let position = translate_position(&input[..], index);
        assert_eq!(position, (0, input.len()));
    }

    #[test]
    fn first_line() {
        let input = b"Hello\nWorld\n";
        let index = 2;
        let position = translate_position(&input[..], index);
        assert_eq!(position, (0, 2));
    }

    #[test]
    fn end_of_line() {
        let input = b"Hello\nWorld\n";
        let index = 5;
        let position = translate_position(&input[..], index);
        assert_eq!(position, (0, 5));
    }

    #[test]
    fn start_of_second_line() {
        let input = b"Hello\nWorld\n";
        let index = 6;
        let position = translate_position(&input[..], index);
        assert_eq!(position, (1, 0));
    }

    #[test]
    fn second_line() {
        let input = b"Hello\nWorld\n";
        let index = 8;
        let position = translate_position(&input[..], index);
        assert_eq!(position, (1, 2));
    }
}