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use anyhow::Context;
use std::fs;
use std::io;
use std::path::Path;
pub const BASE_SUBPATH: &str = "pkgs/by-name";
pub const PACKAGE_NIX_FILENAME: &str = "package.nix";
/// Deterministic file listing so that tests are reproducible
pub fn read_dir_sorted(base_dir: &Path) -> anyhow::Result<Vec<fs::DirEntry>> {
let listing = base_dir
.read_dir()
.with_context(|| format!("Could not list directory {}", base_dir.display()))?;
let mut shard_entries = listing
.collect::<io::Result<Vec<_>>>()
.with_context(|| format!("Could not list directory {}", base_dir.display()))?;
shard_entries.sort_by_key(|entry| entry.file_name());
Ok(shard_entries)
}
/// A simple utility for calculating the line for a string offset.
/// This doesn't do any Unicode handling, though that probably doesn't matter
/// because newlines can't split up Unicode characters. Also this is only used
/// for error reporting
pub struct LineIndex {
/// Stores the indices of newlines
newlines: Vec<usize>,
}
impl LineIndex {
pub fn new(s: &str) -> LineIndex {
let mut newlines = vec![];
let mut index = 0;
// Iterates over all newline-split parts of the string, adding the index of the newline to
// the vec
for split in s.split_inclusive('\n') {
index += split.len();
newlines.push(index - 1);
}
LineIndex { newlines }
}
/// Returns the line number for a string index.
/// If the index points to a newline, returns the line number before the newline
pub fn line(&self, index: usize) -> usize {
match self.newlines.binary_search(&index) {
// +1 because lines are 1-indexed
Ok(x) => x + 1,
Err(x) => x + 1,
}
}
/// Returns the string index for a line and column.
pub fn fromlinecolumn(&self, line: usize, column: usize) -> usize {
// If it's the 1th line, the column is the index
if line == 1 {
// But columns are 1-indexed
column - 1
} else {
// For the nth line, we add the index of the (n-1)st newline to the column,
// and remove one more from the index since arrays are 0-indexed.
// Then add the 1-indexed column to get not the newline index itself,
// but rather the index of the position on the next line
self.newlines[line - 2] + column
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn line_index() {
let line_index = LineIndex::new("a\nbc\n\ndef\n");
let pairs = [
(0, 1, 1),
(1, 1, 2),
(2, 2, 1),
(3, 2, 2),
(4, 2, 3),
(5, 3, 1),
(6, 4, 1),
(7, 4, 2),
(8, 4, 3),
(9, 4, 4),
];
for (index, line, column) in pairs {
assert_eq!(line_index.line(index), line);
assert_eq!(line_index.fromlinecolumn(line, column), index);
}
}
}
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