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// This is a part of Chrono.
// See README.md and LICENSE.txt for details.
/*!
* Various scanning routines for the parser.
*/
#![allow(deprecated)]
use super::{ParseResult, INVALID, OUT_OF_RANGE, TOO_SHORT};
use Weekday;
/// Returns true when two slices are equal case-insensitively (in ASCII).
/// Assumes that the `pattern` is already converted to lower case.
fn equals(s: &str, pattern: &str) -> bool {
let mut xs = s.as_bytes().iter().map(|&c| match c {
b'A'...b'Z' => c + 32,
_ => c,
});
let mut ys = pattern.as_bytes().iter().cloned();
loop {
match (xs.next(), ys.next()) {
(None, None) => return true,
(None, _) | (_, None) => return false,
(Some(x), Some(y)) if x != y => return false,
_ => (),
}
}
}
/// Tries to parse the non-negative number from `min` to `max` digits.
///
/// The absence of digits at all is an unconditional error.
/// More than `max` digits are consumed up to the first `max` digits.
/// Any number that does not fit in `i64` is an error.
#[inline]
pub fn number(s: &str, min: usize, max: usize) -> ParseResult<(&str, i64)> {
assert!(min <= max);
// We are only interested in ascii numbers, so we can work with the `str` as bytes. We stop on
// the first non-numeric byte, which may be another ascii character or beginning of multi-byte
// UTF-8 character.
let bytes = s.as_bytes();
if bytes.len() < min {
return Err(TOO_SHORT);
}
let mut n = 0i64;
for (i, c) in bytes.iter().take(max).cloned().enumerate() {
// cloned() = copied()
if c < b'0' || b'9' < c {
if i < min {
return Err(INVALID);
} else {
return Ok((&s[i..], n));
}
}
n = match n.checked_mul(10).and_then(|n| n.checked_add((c - b'0') as i64)) {
Some(n) => n,
None => return Err(OUT_OF_RANGE),
};
}
Ok((&s[::core::cmp::min(max, bytes.len())..], n))
}
/// Tries to consume at least one digits as a fractional second.
/// Returns the number of whole nanoseconds (0--999,999,999).
pub fn nanosecond(s: &str) -> ParseResult<(&str, i64)> {
// record the number of digits consumed for later scaling.
let origlen = s.len();
let (s, v) = number(s, 1, 9)?;
let consumed = origlen - s.len();
// scale the number accordingly.
static SCALE: [i64; 10] =
[0, 100_000_000, 10_000_000, 1_000_000, 100_000, 10_000, 1_000, 100, 10, 1];
let v = v.checked_mul(SCALE[consumed]).ok_or(OUT_OF_RANGE)?;
// if there are more than 9 digits, skip next digits.
let s = s.trim_left_matches(|c: char| '0' <= c && c <= '9');
Ok((s, v))
}
/// Tries to consume a fixed number of digits as a fractional second.
/// Returns the number of whole nanoseconds (0--999,999,999).
pub fn nanosecond_fixed(s: &str, digits: usize) -> ParseResult<(&str, i64)> {
// record the number of digits consumed for later scaling.
let (s, v) = number(s, digits, digits)?;
// scale the number accordingly.
static SCALE: [i64; 10] =
[0, 100_000_000, 10_000_000, 1_000_000, 100_000, 10_000, 1_000, 100, 10, 1];
let v = v.checked_mul(SCALE[digits]).ok_or(OUT_OF_RANGE)?;
Ok((s, v))
}
/// Tries to parse the month index (0 through 11) with the first three ASCII letters.
pub fn short_month0(s: &str) -> ParseResult<(&str, u8)> {
if s.len() < 3 {
return Err(TOO_SHORT);
}
let buf = s.as_bytes();
let month0 = match (buf[0] | 32, buf[1] | 32, buf[2] | 32) {
(b'j', b'a', b'n') => 0,
(b'f', b'e', b'b') => 1,
(b'm', b'a', b'r') => 2,
(b'a', b'p', b'r') => 3,
(b'm', b'a', b'y') => 4,
(b'j', b'u', b'n') => 5,
(b'j', b'u', b'l') => 6,
(b'a', b'u', b'g') => 7,
(b's', b'e', b'p') => 8,
(b'o', b'c', b't') => 9,
(b'n', b'o', b'v') => 10,
(b'd', b'e', b'c') => 11,
_ => return Err(INVALID),
};
Ok((&s[3..], month0))
}
/// Tries to parse the weekday with the first three ASCII letters.
pub fn short_weekday(s: &str) -> ParseResult<(&str, Weekday)> {
if s.len() < 3 {
return Err(TOO_SHORT);
}
let buf = s.as_bytes();
let weekday = match (buf[0] | 32, buf[1] | 32, buf[2] | 32) {
(b'm', b'o', b'n') => Weekday::Mon,
(b't', b'u', b'e') => Weekday::Tue,
(b'w', b'e', b'd') => Weekday::Wed,
(b't', b'h', b'u') => Weekday::Thu,
(b'f', b'r', b'i') => Weekday::Fri,
(b's', b'a', b't') => Weekday::Sat,
(b's', b'u', b'n') => Weekday::Sun,
_ => return Err(INVALID),
};
Ok((&s[3..], weekday))
}
/// Tries to parse the month index (0 through 11) with short or long month names.
/// It prefers long month names to short month names when both are possible.
pub fn short_or_long_month0(s: &str) -> ParseResult<(&str, u8)> {
// lowercased month names, minus first three chars
static LONG_MONTH_SUFFIXES: [&'static str; 12] =
["uary", "ruary", "ch", "il", "", "e", "y", "ust", "tember", "ober", "ember", "ember"];
let (mut s, month0) = short_month0(s)?;
// tries to consume the suffix if possible
let suffix = LONG_MONTH_SUFFIXES[month0 as usize];
if s.len() >= suffix.len() && equals(&s[..suffix.len()], suffix) {
s = &s[suffix.len()..];
}
Ok((s, month0))
}
/// Tries to parse the weekday with short or long weekday names.
/// It prefers long weekday names to short weekday names when both are possible.
pub fn short_or_long_weekday(s: &str) -> ParseResult<(&str, Weekday)> {
// lowercased weekday names, minus first three chars
static LONG_WEEKDAY_SUFFIXES: [&'static str; 7] =
["day", "sday", "nesday", "rsday", "day", "urday", "day"];
let (mut s, weekday) = short_weekday(s)?;
// tries to consume the suffix if possible
let suffix = LONG_WEEKDAY_SUFFIXES[weekday.num_days_from_monday() as usize];
if s.len() >= suffix.len() && equals(&s[..suffix.len()], suffix) {
s = &s[suffix.len()..];
}
Ok((s, weekday))
}
/// Tries to consume exactly one given character.
pub fn char(s: &str, c1: u8) -> ParseResult<&str> {
match s.as_bytes().first() {
Some(&c) if c == c1 => Ok(&s[1..]),
Some(_) => Err(INVALID),
None => Err(TOO_SHORT),
}
}
/// Tries to consume one or more whitespace.
pub fn space(s: &str) -> ParseResult<&str> {
let s_ = s.trim_left();
if s_.len() < s.len() {
Ok(s_)
} else if s.is_empty() {
Err(TOO_SHORT)
} else {
Err(INVALID)
}
}
/// Consumes any number (including zero) of colon or spaces.
pub fn colon_or_space(s: &str) -> ParseResult<&str> {
Ok(s.trim_left_matches(|c: char| c == ':' || c.is_whitespace()))
}
/// Tries to parse `[-+]\d\d` continued by `\d\d`. Return an offset in seconds if possible.
///
/// The additional `colon` may be used to parse a mandatory or optional `:`
/// between hours and minutes, and should return either a new suffix or `Err` when parsing fails.
pub fn timezone_offset<F>(s: &str, consume_colon: F) -> ParseResult<(&str, i32)>
where
F: FnMut(&str) -> ParseResult<&str>,
{
timezone_offset_internal(s, consume_colon, false)
}
fn timezone_offset_internal<F>(
mut s: &str,
mut consume_colon: F,
allow_missing_minutes: bool,
) -> ParseResult<(&str, i32)>
where
F: FnMut(&str) -> ParseResult<&str>,
{
fn digits(s: &str) -> ParseResult<(u8, u8)> {
let b = s.as_bytes();
if b.len() < 2 {
Err(TOO_SHORT)
} else {
Ok((b[0], b[1]))
}
}
let negative = match s.as_bytes().first() {
Some(&b'+') => false,
Some(&b'-') => true,
Some(_) => return Err(INVALID),
None => return Err(TOO_SHORT),
};
s = &s[1..];
// hours (00--99)
let hours = match digits(s)? {
(h1 @ b'0'...b'9', h2 @ b'0'...b'9') => i32::from((h1 - b'0') * 10 + (h2 - b'0')),
_ => return Err(INVALID),
};
s = &s[2..];
// colons (and possibly other separators)
s = consume_colon(s)?;
// minutes (00--59)
// if the next two items are digits then we have to add minutes
let minutes = if let Ok(ds) = digits(s) {
match ds {
(m1 @ b'0'...b'5', m2 @ b'0'...b'9') => i32::from((m1 - b'0') * 10 + (m2 - b'0')),
(b'6'...b'9', b'0'...b'9') => return Err(OUT_OF_RANGE),
_ => return Err(INVALID),
}
} else if allow_missing_minutes {
0
} else {
return Err(TOO_SHORT);
};
s = match s.len() {
len if len >= 2 => &s[2..],
len if len == 0 => s,
_ => return Err(TOO_SHORT),
};
let seconds = hours * 3600 + minutes * 60;
Ok((s, if negative { -seconds } else { seconds }))
}
/// Same as `timezone_offset` but also allows for `z`/`Z` which is the same as `+00:00`.
pub fn timezone_offset_zulu<F>(s: &str, colon: F) -> ParseResult<(&str, i32)>
where
F: FnMut(&str) -> ParseResult<&str>,
{
let bytes = s.as_bytes();
match bytes.first() {
Some(&b'z') | Some(&b'Z') => Ok((&s[1..], 0)),
Some(&b'u') | Some(&b'U') => {
if bytes.len() >= 3 {
let (b, c) = (bytes[1], bytes[2]);
match (b | 32, c | 32) {
(b't', b'c') => Ok((&s[3..], 0)),
_ => Err(INVALID),
}
} else {
Err(INVALID)
}
}
_ => timezone_offset(s, colon),
}
}
/// Same as `timezone_offset` but also allows for `z`/`Z` which is the same as
/// `+00:00`, and allows missing minutes entirely.
pub fn timezone_offset_permissive<F>(s: &str, colon: F) -> ParseResult<(&str, i32)>
where
F: FnMut(&str) -> ParseResult<&str>,
{
match s.as_bytes().first() {
Some(&b'z') | Some(&b'Z') => Ok((&s[1..], 0)),
_ => timezone_offset_internal(s, colon, true),
}
}
/// Same as `timezone_offset` but also allows for RFC 2822 legacy timezones.
/// May return `None` which indicates an insufficient offset data (i.e. `-0000`).
pub fn timezone_offset_2822(s: &str) -> ParseResult<(&str, Option<i32>)> {
// tries to parse legacy time zone names
let upto = s
.as_bytes()
.iter()
.position(|&c| match c {
b'a'...b'z' | b'A'...b'Z' => false,
_ => true,
})
.unwrap_or_else(|| s.len());
if upto > 0 {
let name = &s[..upto];
let s = &s[upto..];
let offset_hours = |o| Ok((s, Some(o * 3600)));
if equals(name, "gmt") || equals(name, "ut") {
offset_hours(0)
} else if equals(name, "edt") {
offset_hours(-4)
} else if equals(name, "est") || equals(name, "cdt") {
offset_hours(-5)
} else if equals(name, "cst") || equals(name, "mdt") {
offset_hours(-6)
} else if equals(name, "mst") || equals(name, "pdt") {
offset_hours(-7)
} else if equals(name, "pst") {
offset_hours(-8)
} else {
Ok((s, None)) // recommended by RFC 2822: consume but treat it as -0000
}
} else {
let (s_, offset) = timezone_offset(s, |s| Ok(s))?;
Ok((s_, Some(offset)))
}
}
/// Tries to consume everyting until next whitespace-like symbol.
/// Does not provide any offset information from the consumed data.
pub fn timezone_name_skip(s: &str) -> ParseResult<(&str, ())> {
Ok((s.trim_left_matches(|c: char| !c.is_whitespace()), ()))
}