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[wc] faster character count #248

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merged 3 commits into from
Sep 25, 2024
Merged

[wc] faster character count #248

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baa0cba
[wc] remove w_space from CountInfo
gcanat Sep 23, 2024
bab885c
[wc] count chars from bytes
gcanat Sep 23, 2024
98b7fc9
[wc] remove global variable from function parameters
gcanat Sep 23, 2024
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70 changes: 16 additions & 54 deletions text/wc.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ use clap::Parser;
use gettextrs::{bind_textdomain_codeset, setlocale, textdomain, LocaleCategory};
use plib::PROJECT_NAME;
use std::ffi::OsStr;
use std::io::{self, BufRead, Read};
use std::io::{self, Read};
use std::path::PathBuf;

/// wc - word, line, and byte or character count
Expand Down Expand Up @@ -42,7 +42,6 @@ struct CountInfo {
words: usize,
chars: usize,
nl: usize,
was_space: bool,
}

impl CountInfo {
Expand All @@ -51,7 +50,6 @@ impl CountInfo {
words: 0,
chars: 0,
nl: 0,
was_space: true,
}
}

Expand Down Expand Up @@ -124,67 +122,36 @@ fn build_display_str(args: &Args, count: &CountInfo, filename: &OsStr) -> String
output
}

fn wc_file_bytes(count: &mut CountInfo, pathname: &PathBuf, table: &[bool; 256]) -> io::Result<()> {
fn wc_file_bytes(count: &mut CountInfo, pathname: &PathBuf, chars_mode: bool) -> io::Result<()> {
let mut file = plib::io::input_stream(pathname, false)?;

let mut buffer = [0; plib::BUFSZ];
let mut was_space = count.was_space;
let mut was_space = true;

loop {
let n_read = file.read(&mut buffer[..])?;
if n_read == 0 {
break;
}

count.chars = count.chars + n_read;

let bufslice = &buffer[0..n_read];

if !chars_mode {
// number of bytes read
count.chars = count.chars + n_read;
} else {
// number of UTF-8 unicode codepoints in this slice of bytes
count.chars += bufslice.iter().filter(|&ch| (ch >> 6) != 0b10).count();
}


for ch_u8 in bufslice {
let is_space = table[*ch_u8 as usize];
let is_space = BYTE_TABLE[*ch_u8 as usize];
count.nl += (ch_u8 == &10) as usize;
count.words += (!is_space && was_space) as usize;
was_space = is_space;
}
}
count.was_space = was_space;

Ok(())
}

fn wc_file_chars(args: &Args, count: &mut CountInfo, pathname: &PathBuf) -> io::Result<()> {
let mut reader = plib::io::input_reader(pathname, false)?;

loop {
let mut buffer = String::new();
let n_read = reader.read_line(&mut buffer)?;
if n_read == 0 {
break;
}

count.nl = count.nl + 1;
count.chars = count.chars + n_read;

if args.words {
let mut in_word = false;

for ch in buffer.chars() {
if ch.is_whitespace() {
if in_word {
in_word = false;
count.words = count.words + 1;
}
} else {
if !in_word {
in_word = true;
}
}
}
if in_word {
count.words = count.words + 1;
}
}
}

Ok(())
}
Expand All @@ -194,13 +161,8 @@ fn wc_file(
chars_mode: bool,
pathname: &PathBuf,
count: &mut CountInfo,
table: &[bool; 256],
) -> io::Result<()> {
if chars_mode {
wc_file_chars(args, count, pathname)?;
} else {
wc_file_bytes(count, pathname, table)?;
}
wc_file_bytes(count, pathname, chars_mode)?;

let output = build_display_str(args, count, pathname.as_os_str());

Expand Down Expand Up @@ -236,7 +198,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
if args.files.is_empty() {
let mut count = CountInfo::new();

if let Err(e) = wc_file(&args, chars_mode, &PathBuf::new(), &mut count, &BYTE_TABLE) {
if let Err(e) = wc_file(&args, chars_mode, &PathBuf::new(), &mut count) {
exit_code = 1;
eprintln!("stdin: {}", e);
}
Expand All @@ -246,7 +208,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
for filename in &args.files {
let mut count = CountInfo::new();

if let Err(e) = wc_file(&args, chars_mode, filename, &mut count, &BYTE_TABLE) {
if let Err(e) = wc_file(&args, chars_mode, filename, &mut count) {
exit_code = 1;
eprintln!("{}: {}", filename.display(), e);
}
Expand Down