verbena 0.1.0

Scripting language
Documentation 
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

/// An error that occurred during parsing or processing.
///
/// Contains the position where the error occurred (`caret`) and a descriptive message (`msg`).
pub struct Error {
    /// The character position where the error occurred in the input.
    pub caret: usize,
    /// A human-readable error message describing the problem.
    pub msg: String,
}

impl Error {
    /// Formats the error into a user-friendly multi-line string with context.
    ///
    /// # Arguments
    ///
    /// * `file` - The name of the file where the error occurred
    /// * `input_text` - The input text being processed when the error occurred
    ///
    /// # Returns
    ///
    /// A formatted error message that includes:
    /// - The file and line number where the error occurred
    /// - The line of text containing the error
    /// - A caret (^) pointing to the exact position of the error
    /// - The error message
    pub fn format_error(&self, file: &str, input_text: &[char]) -> String {
        // Calculate line number by counting newlines up to caret position
        let line_number = input_text[..self.caret]
            .iter()
            .filter(|&&c| c == '\n')
            .count()
            + 1;

        // Find the start and end indices of the error line
        let line_start = input_text[..self.caret]
            .iter()
            .rposition(|&c| c == '\n')
            .map_or(0, |pos| pos + 1);

        let line_end = input_text[self.caret..]
            .iter()
            .position(|&c| c == '\n')
            .map_or(input_text.len(), |pos| self.caret + pos);

        // Extract the line containing the error
        let error_line: String = input_text[line_start..line_end].iter().collect();

        // Calculate column position within the line
        let column = self.caret - line_start;

        // Build the multi-line error message
        let mut result = String::new();
        result.push_str(&format!("{}:{}:\n", file, line_number));
        result.push_str(&format!("{}\n", error_line));
        result.push_str(&format!("{}^\n", " ".repeat(column)));
        result.push_str(&self.msg.to_string());
        result
    }
}