feat(core): implement FileReader with memchr line indexing
This commit is contained in:
dailz
@@ -1,13 +1,138 @@
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use crate::error::Result;
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use std::path::Path;
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use crate::error::{CoreError, Result};
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use crate::io::line_index::LineIndex;
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use std::path::{Path, PathBuf};
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pub struct FileReader {/* TODO */}
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pub struct FileReader {
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path: PathBuf,
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data: Vec<u8>,
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line_index: LineIndex,
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}
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impl FileReader {
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pub fn open(_path: &Path) -> Result<Self> {
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todo!()
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pub fn open(path: &Path) -> Result<Self> {
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let data = std::fs::read(path)?;
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if std::str::from_utf8(&data).is_err() {
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return Err(CoreError::Encoding {
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line: 0,
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bytes: data.iter().take(64).copied().collect(),
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});
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}
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let line_index = LineIndex::from_bytes(&data);
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Ok(FileReader {
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path: path.to_path_buf(),
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data,
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line_index,
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})
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}
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pub fn data(&self) -> &[u8] {
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&self.data
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}
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pub fn line_count(&self) -> usize {
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self.line_index.line_count()
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}
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pub fn get_line(&self, idx: usize) -> Option<&str> {
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self.line_index.get_line(&self.data, idx)
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}
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pub fn file_size(&self) -> u64 {
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todo!()
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self.data.len() as u64
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}
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pub fn path(&self) -> &Path {
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&self.path
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use std::env::temp_dir;
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fn temp_path(name: &str) -> PathBuf {
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temp_dir().join(name)
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}
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#[test]
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fn test_empty_file() {
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let path = temp_path("file_reader_test_empty");
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std::fs::write(&path, b"").unwrap();
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let reader = FileReader::open(&path).unwrap();
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assert_eq!(reader.line_count(), 0);
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let _ = std::fs::remove_file(&path);
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}
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#[test]
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fn test_multi_line_file() {
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let path = temp_path("file_reader_test_multi");
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std::fs::write(&path, b"hello\nworld\nfoo").unwrap();
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let reader = FileReader::open(&path).unwrap();
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assert_eq!(reader.line_count(), 3);
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assert_eq!(reader.get_line(0), Some("hello"));
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assert_eq!(reader.get_line(1), Some("world"));
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assert_eq!(reader.get_line(2), Some("foo"));
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let _ = std::fs::remove_file(&path);
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}
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#[test]
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fn test_nonexistent_file() {
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let path = temp_path("file_reader_test_nonexistent_xyzzy");
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let _ = std::fs::remove_file(&path);
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let result = FileReader::open(&path);
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match result {
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Err(CoreError::Io { .. }) => {}
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Err(other) => panic!("expected Io variant, got {other:?}"),
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Ok(_) => panic!("expected error, got success"),
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}
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}
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#[test]
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fn test_non_utf8_file() {
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let path = temp_path("file_reader_test_nonutf8");
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std::fs::write(&path, &[0xFF, 0xFE]).unwrap();
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let result = FileReader::open(&path);
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match result {
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Err(CoreError::Encoding { line, bytes }) => {
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assert_eq!(line, 0);
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assert_eq!(bytes, vec![0xFF, 0xFE]);
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}
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Err(other) => panic!("expected Encoding variant, got {other:?}"),
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Ok(_) => panic!("expected error, got success"),
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}
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let _ = std::fs::remove_file(&path);
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}
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#[test]
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fn test_file_size() {
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let path = temp_path("file_reader_test_size");
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let content = b"hello world";
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std::fs::write(&path, content).unwrap();
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let reader = FileReader::open(&path).unwrap();
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assert_eq!(reader.file_size(), content.len() as u64);
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let _ = std::fs::remove_file(&path);
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}
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#[test]
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fn test_path() {
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let path = temp_path("file_reader_test_path");
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std::fs::write(&path, b"data").unwrap();
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let reader = FileReader::open(&path).unwrap();
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assert_eq!(reader.path(), path);
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let _ = std::fs::remove_file(&path);
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}
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#[test]
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fn test_single_line_no_newline() {
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let path = temp_path("file_reader_test_single");
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std::fs::write(&path, b"hello").unwrap();
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let reader = FileReader::open(&path).unwrap();
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assert_eq!(reader.line_count(), 1);
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assert_eq!(reader.get_line(0), Some("hello"));
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let _ = std::fs::remove_file(&path);
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}
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}
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@@ -1 +1,140 @@
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pub struct LineIndex {/* TODO */}
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pub struct LineIndex {
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line_starts: Vec<usize>,
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#[allow(dead_code)]
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has_trailing_newline: bool,
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}
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impl LineIndex {
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pub fn from_bytes(data: &[u8]) -> Self {
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if data.is_empty() {
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return LineIndex {
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line_starts: vec![],
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has_trailing_newline: false,
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};
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}
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let mut line_starts = vec![0usize];
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for pos in memchr::memchr_iter(b'\n', data) {
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line_starts.push(pos + 1);
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}
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let trailing = data.last().is_some_and(|&b| b == b'\n');
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if trailing {
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line_starts.pop();
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}
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LineIndex {
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line_starts,
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has_trailing_newline: trailing,
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}
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}
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pub fn line_count(&self) -> usize {
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self.line_starts.len()
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}
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pub fn get_line<'a>(&self, data: &'a [u8], idx: usize) -> Option<&'a str> {
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if idx >= self.line_starts.len() {
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return None;
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}
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let start = self.line_starts[idx];
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let end = if idx + 1 < self.line_starts.len() {
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self.line_starts[idx + 1].saturating_sub(1)
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} else {
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data.len()
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};
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let slice = &data[start..end];
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std::str::from_utf8(slice)
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.map(|s| s.trim_end_matches(['\r', '\n']))
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.ok()
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_empty_data() {
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let idx = LineIndex::from_bytes(b"");
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assert_eq!(idx.line_count(), 0);
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}
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#[test]
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fn test_single_line_no_newline() {
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let data = b"hello";
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let idx = LineIndex::from_bytes(data);
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assert_eq!(idx.line_count(), 1);
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assert_eq!(idx.get_line(data, 0), Some("hello"));
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}
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#[test]
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fn test_single_line_with_newline() {
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let data = b"hello\n";
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let idx = LineIndex::from_bytes(data);
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assert_eq!(idx.line_count(), 1);
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assert_eq!(idx.get_line(data, 0), Some("hello"));
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}
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#[test]
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fn test_multi_line() {
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let data = b"aaa\nbbb\nccc";
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let idx = LineIndex::from_bytes(data);
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assert_eq!(idx.line_count(), 3);
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assert_eq!(idx.get_line(data, 0), Some("aaa"));
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assert_eq!(idx.get_line(data, 1), Some("bbb"));
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assert_eq!(idx.get_line(data, 2), Some("ccc"));
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}
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#[test]
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fn test_crlf_endings() {
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let data = b"hello\r\nworld\r\n";
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let idx = LineIndex::from_bytes(data);
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assert_eq!(idx.line_count(), 2);
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assert_eq!(idx.get_line(data, 0), Some("hello"));
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assert_eq!(idx.get_line(data, 1), Some("world"));
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}
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#[test]
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fn test_only_newline() {
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let data = b"\n";
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let idx = LineIndex::from_bytes(data);
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assert_eq!(idx.line_count(), 1);
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assert_eq!(idx.get_line(data, 0), Some(""));
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}
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#[test]
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fn test_consecutive_newlines() {
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let data = b"a\n\nb";
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let idx = LineIndex::from_bytes(data);
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assert_eq!(idx.line_count(), 3);
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assert_eq!(idx.get_line(data, 0), Some("a"));
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assert_eq!(idx.get_line(data, 1), Some(""));
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assert_eq!(idx.get_line(data, 2), Some("b"));
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}
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#[test]
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fn test_double_newline() {
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let data = b"\n\n";
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let idx = LineIndex::from_bytes(data);
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assert_eq!(idx.line_count(), 2);
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assert_eq!(idx.get_line(data, 0), Some(""));
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assert_eq!(idx.get_line(data, 1), Some(""));
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}
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#[test]
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fn test_out_of_bounds() {
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let data = b"hello";
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let idx = LineIndex::from_bytes(data);
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assert_eq!(idx.get_line(data, 999), None);
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}
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#[test]
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fn test_empty_file_line_count_and_get_line() {
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let idx = LineIndex::from_bytes(b"");
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assert_eq!(idx.line_count(), 0);
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assert_eq!(idx.get_line(b"", 0), None);
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}
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}
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