Merge PR #1942: CSV import: read Windows-1256 Arabic files as Arabic

This commit is contained in:
aiongg
2026-10-22 02:35:20 +00:00
4 changed files with 217 additions and 14 deletions
+114 -8
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@@ -17,7 +17,107 @@ const CP1252: [u32; 32] = [
0x201C, 0x201D, 0x2022, 0x2013, 0x2014, 0x02DC, 0x2122, 0x0161, 0x203A, 0x0153, 0x9D, 0x017E, 0x0178,
];
/// Decodes CSV bytes: UTF-8/UTF-16 BOMs, else UTF-8, else Windows-1252.
/// Windows-1256 code points for bytes 0x80–0xFF (unicode.org `CP1256.TXT`).
pub(crate) const CP1256: [u32; 128] = [
0x20AC, 0x067E, 0x201A, 0x0192, 0x201E, 0x2026, 0x2020, 0x2021, 0x02C6, 0x2030, 0x0679, 0x2039, 0x0152, 0x0686, 0x0698, 0x0688, 0x06AF, 0x2018,
0x2019, 0x201C, 0x201D, 0x2022, 0x2013, 0x2014, 0x06A9, 0x2122, 0x0691, 0x203A, 0x0153, 0x200C, 0x200D, 0x06BA, 0x00A0, 0x060C, 0x00A2, 0x00A3,
0x00A4, 0x00A5, 0x00A6, 0x00A7, 0x00A8, 0x00A9, 0x06BE, 0x00AB, 0x00AC, 0x00AD, 0x00AE, 0x00AF, 0x00B0, 0x00B1, 0x00B2, 0x00B3, 0x00B4, 0x00B5,
0x00B6, 0x00B7, 0x00B8, 0x00B9, 0x061B, 0x00BB, 0x00BC, 0x00BD, 0x00BE, 0x061F, 0x06C1, 0x0621, 0x0622, 0x0623, 0x0624, 0x0625, 0x0626, 0x0627,
0x0628, 0x0629, 0x062A, 0x062B, 0x062C, 0x062D, 0x062E, 0x062F, 0x0630, 0x0631, 0x0632, 0x0633, 0x0634, 0x0635, 0x0636, 0x00D7, 0x0637, 0x0638,
0x0639, 0x063A, 0x0640, 0x0641, 0x0642, 0x0643, 0x00E0, 0x0644, 0x00E2, 0x0645, 0x0646, 0x0647, 0x0648, 0x00E7, 0x00E8, 0x00E9, 0x00EA, 0x00EB,
0x0649, 0x064A, 0x00EE, 0x00EF, 0x064B, 0x064C, 0x064D, 0x064E, 0x00F4, 0x064F, 0x0650, 0x00F7, 0x0651, 0x00F9, 0x0652, 0x00FB, 0x00FC, 0x200E,
0x200F, 0x06D2,
];
/// Evidence that bytes which aren't UTF-8 are Windows-1256 Arabic rather than Windows-1252.
#[derive(Default)]
struct Cp1256Evidence {
/// High bytes that decode to different characters in the two code pages, apart from invisible
/// marks and ordinals after a digit.
differing: usize,
/// Of those, Arabic letters and Arabic punctuation (، ؛ ؟) in Windows-1256.
arabic: usize,
/// Arabic bytes next to an ASCII letter: Western accents sit inside Latin words, Arabic doesn't.
arabic_touching_latin: usize,
/// Accented Latin bytes the two code pages share, next to another high byte: Hebrew
/// Windows-1255 letters land there, Arabic and Western text rarely do.
shared_letters_in_runs: usize,
}
impl Cp1256Evidence {
fn of(bytes: &[u8]) -> Self {
let mut e = Self::default();
for (i, &b) in bytes.iter().enumerate() {
if b < 0x80 {
continue;
}
let before = i.checked_sub(1).and_then(|j| bytes.get(j)).copied();
let after = bytes.get(i + 1).copied();
let next_to = |pred: fn(u8) -> bool| before.is_some_and(pred) || after.is_some_and(pred);
if same_in_cp1252_and_cp1256(b) {
if is_shared_latin_letter(b) && next_to(|x| x >= 0x80) {
e.shared_letters_in_runs += 1;
}
continue;
}
if is_invisible_mark(b) || is_ordinal_after_digit(b, before) {
continue;
}
e.differing += 1;
if is_cp1256_arabic(b) {
e.arabic += 1;
if next_to(|x| x.is_ascii_alphabetic()) {
e.arabic_touching_latin += 1;
}
}
}
e
}
/// Thresholds chosen against month, day and language names from 95 glibc locales (Western in
/// Windows-1252, Arabic, Persian and Urdu in 1256, Hebrew and Yiddish in 1255) plus CSV samples.
fn is_arabic(&self) -> bool {
self.arabic >= 2
&& self.arabic * 10 >= self.differing * 9
&& self.arabic_touching_latin * 10 <= self.arabic * 3
&& self.shared_letters_in_runs * 20 <= self.arabic
}
}
fn same_in_cp1252_and_cp1256(b: u8) -> bool {
matches!(
b,
0x80 | 0x82..=0x89 | 0x8B..=0x8C | 0x91..=0x97 | 0x99 | 0x9B..=0x9C | 0xA0 | 0xA2..=0xA9 | 0xAB..=0xB9 | 0xBB..=0xBE | 0xD7 | 0xE0 | 0xE2 | 0xE7..=0xEB
| 0xEE..=0xEF | 0xF4 | 0xF7 | 0xF9 | 0xFB..=0xFC
)
}
/// ZWNJ, ZWJ, LRM and RLM: common inside Persian words and around Arabic cells, but no evidence
/// either way.
fn is_invisible_mark(b: u8) -> bool {
matches!(b, 0x9D | 0x9E | 0xFD | 0xFE)
}
/// `º` and `ª` after a digit (`1º`, `2ª`) are Western ordinals, though Windows-1256 reads the bytes
/// as `؛` and `ھ`; either way they are no evidence.
fn is_ordinal_after_digit(b: u8, before: Option<u8>) -> bool {
matches!(b, 0xAA | 0xBA) && before.is_some_and(|x| x.is_ascii_digit())
}
fn is_shared_latin_letter(b: u8) -> bool {
matches!(b, 0xE0 | 0xE2 | 0xE7..=0xEB | 0xEE..=0xEF | 0xF4 | 0xF9 | 0xFB..=0xFC)
}
fn is_cp1256_arabic(b: u8) -> bool {
matches!(
b,
0x81 | 0x8A | 0x8D..=0x90 | 0x98 | 0x9A | 0x9F | 0xA1 | 0xAA | 0xBA | 0xBF..=0xD6 | 0xD8..=0xDB | 0xDD..=0xDF | 0xE1 | 0xE3..=0xE6 | 0xEC..=0xED | 0xFF
)
}
/// Decodes CSV bytes with BOM-aware UTF-8 and UTF-16 handling. Without a BOM, valid UTF-8 is kept.
/// Other bytes decode as Windows-1256 when they read as Arabic (see [`Cp1256Evidence`]), else as
/// Windows-1252.
pub fn decode_text(bytes: &[u8]) -> String {
if let Some(rest) = bytes.strip_prefix(&[0xEF, 0xBB, 0xBF]) {
return String::from_utf8_lossy(rest).into_owned();
@@ -34,13 +134,19 @@ pub fn decode_text(bytes: &[u8]) -> String {
}
match std::str::from_utf8(bytes) {
Ok(s) => s.to_string(),
Err(_) => bytes
.iter()
.map(|&b| match b {
0x80..=0x9F => char::from_u32(CP1252.get((b - 0x80) as usize).copied().unwrap_or(0xFFFD)).unwrap_or('\u{FFFD}'),
_ => b as char,
})
.collect(),
Err(_) => {
let use_windows_1256 = Cp1256Evidence::of(bytes).is_arabic();
bytes
.iter()
.map(|&b| match b {
0x80..=0xFF if use_windows_1256 => {
char::from_u32(CP1256.get((b - 0x80) as usize).copied().unwrap_or(0xFFFD)).unwrap_or('\u{FFFD}')
}
0x80..=0x9F => char::from_u32(CP1252.get((b - 0x80) as usize).copied().unwrap_or(0xFFFD)).unwrap_or('\u{FFFD}'),
_ => b as char,
})
.collect()
}
}
}
+95
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@@ -68,6 +68,101 @@ fn encodings() {
assert_eq!(v(&wb, 0, 1), Value::Number(1.0));
}
#[test]
fn windows_1256_table_matches_the_unicode_mapping() {
let at = |b: u8| crate::csv::CP1256.get(usize::from(b - 0x80)).and_then(|&c| char::from_u32(c));
let expected = [
(0x80, '€'),
(0x81, 'پ'),
(0x8D, 'چ'),
(0x98, 'ک'),
(0x9D, '\u{200C}'),
(0xA1, '،'),
(0xBA, '؛'),
(0xBF, '؟'),
(0xC7, 'ا'),
(0xC8, 'ب'),
(0xDC, 'ـ'),
(0xE1, 'ل'),
(0xE3, 'م'),
(0xE9, 'é'),
(0xFD, '\u{200E}'),
(0xFE, '\u{200F}'),
(0xFF, 'ے'),
];
for (b, c) in expected {
assert_eq!(at(b), Some(c), "0x{b:02X}");
}
}
#[test]
fn arabic_csv_in_windows_1256_reads_as_arabic() {
let bytes = [
0xC7, 0xE1, 0xC7, 0xD3, 0xE3, b',', 0xC7, 0xE1, 0xDE, 0xED, 0xE3, 0xC9, b'\n', 0xE3, 0xD1, 0xCD, 0xC8, 0xC7, b' ', b'1', b'2', b'3', 0xA1,
b' ', b'4', b'2', 0xBF, b',', 0xC8, 0xED, 0xC7, 0xE4, 0xC7, 0xCA, b' ', b'7', b'\n',
];
let wb = read_csv(&bytes, &CsvOptions::default()).unwrap();
assert_eq!(v(&wb, 0, 0), Value::text("الاسم"));
assert_eq!(v(&wb, 0, 1), Value::text("القيمة"));
assert_eq!(v(&wb, 1, 0), Value::text("مرحبا 123، 42؟"));
assert_eq!(v(&wb, 1, 1), Value::text("بيانات 7"));
}
fn reads_as_arabic(bytes: &[u8]) -> bool {
decode_text(bytes).chars().any(|c| ('\u{0600}'..='\u{06FF}').contains(&c))
}
#[test]
fn western_1252_text_stays_latin() {
let french = [
b'C', b'r', 0xE8, b'm', b'e', b' ', b'b', b'r', 0xFB, b'l', 0xE9, b'e', b',', b' ', 0xE0, b' ', b'c', 0xF4, b't', 0xE9, b',', b' ', 0xE9,
b't', 0xE9,
];
let german = [
b'G', b'r', 0xF6, 0xDF, b'e', b',', b' ', 0xDC, b'b', b'e', b'r', b'm', b'a', 0xDF, b',', b' ', b'F', b'u', 0xDF, b'g', 0xE4, b'n', b'g',
b'e', b'r',
];
assert_eq!(decode_text(&french), "Crème brûlée, à côté, été");
assert_eq!(decode_text(&german), "Größe, Übermaß, Fußgänger");
let portuguese = [
b'A', 0xC7, 0xC3, b'O', b',', b' ', b'i', b'n', b'f', b'o', b'r', b'm', b'a', 0xE7, 0xE3, b'o', b',', b' ', b's', b'i', b't', b'u', b'a',
0xE7, 0xE3, b'o', b',', b' ', b'P', 0xE3, b'o',
];
assert_eq!(decode_text(&portuguese), "AÇÃO, informação, situação, Pão");
let nordic = [
0xC6, b'r', 0xF8, b',', 0xD8, b's', b't', b',', 0xC5, b's', b'e', b',', 0xDE, 0xF3, b'r', 0xF0, b'u', b'r', b',', b'G', b'u', 0xF0, b'r',
0xFA, b'n', b',', 0xC4, 0xD6, 0xDC,
];
assert_eq!(decode_text(&nordic), "Ærø,Øst,Åse,Þórður,Guðrún,ÄÖÜ");
let ordinals = [b'1', 0xBA, b',', b'2', 0xBA, b',', b'3', 0xBA, b'\n', b'1', 0xAA, b',', b'2', 0xAA];
assert_eq!(decode_text(&ordinals), "1º,2º,3º\n1ª,2ª");
let inside_words = [b'K', 0xE4, b's', b'e', b',', b'B', 0xE4, b'c', b'k', b'e', b'r'];
assert_eq!(decode_text(&inside_words), "Käse,Bäcker");
}
#[test]
fn short_arabic_words_read_as_arabic() {
assert_eq!(decode_text(&[0xDD, 0xED, b',', 0xE3, 0xE4, b',', 0xDA, 0xE4, b'\n']), "في,من,عن\n");
assert_eq!(decode_text(&[0xE4, 0xDA, 0xE3, b',', 0xE1, 0xC7, b'\n', 0xE1, 0xC7, b',', 0xE4, 0xDA, 0xE3, b'\n']), "نعم,لا\nلا,نعم\n");
assert_eq!(decode_text(&[0x98, 0xCA, 0xC7, 0xC8, b' ', 0x81, 0xC7, 0xD1, 0xD3, 0xED]), "کتاب پارسي");
let with_marks = [
0xDF, 0xCA, 0xC7, 0xC8, 0x9D, 0xE5, 0xC7, b',', 0xCE, 0xC7, 0xE4, 0xE5, 0x9D, 0xE5, 0xC7, b',', 0xE3, 0xCD, 0xE3, 0xCF, 0xFE, b',', 0xDA,
0xE1, 0xED, 0xFE,
];
assert_eq!(decode_text(&with_marks), "كتاب\u{200C}ها,خانه\u{200C}ها,محمد\u{200F},علي\u{200F}");
}
#[test]
fn hebrew_1255_bytes_are_not_read_as_arabic() {
let plain = [0xF9, 0xEC, 0xE5, 0xED, b',', 0xF2, 0xE5, 0xEC, 0xED];
let pointed = [0xF9, 0xC8, 0xD1, 0xEC, 0xE5, 0xC9, 0xED, b' ', 0xF2, 0xE5, 0xC9, 0xEC, 0xC8, 0xED];
let maqaf = [0xFA, 0xEC, 0xCE, 0xE0, 0xE1, 0xE9, 0xE1, b',', 0xE1, 0xEF, 0xCE, 0xE2, 0xE5, 0xF8, 0xE9, 0xE5, 0xEF];
let gershayim = [0xF6, 0xE4, 0xD8, 0xEC, b',', 0xE3, 0xD8, 0xF8];
for bytes in [&plain[..], &pointed, &maqaf, &gershayim] {
assert!(!reads_as_arabic(bytes), "{:?}", decode_text(bytes));
}
}
#[test]
fn delimiter_sniffing() {
assert_eq!(sniff_delimiter("a;b;c\n1;2;3\n", '"'), b';');