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use core::str::Bytes;
use super::Unit;
use crate::{common::get_char_from_bytes, UnitParseError};
/// Associated functions for parsing strings.
impl Unit {
/// Create a new `Unit` instance from a string.
/// The string may be `""`, `"B"`, `"M"`, `"MB"`, `"MiB"`, `"b"`, `"Mb"`, `"Mbit"`.
///
/// You can ignore the case of **"B"** (byte), which means **b** will still be treated as bytes instead of bits.
///
/// If the input string is empty, it will return `B` if `prefer_byte` is true; otherwise, it will return `b`. Similarly, if the string is not empty but it does not explicitly contains `"B"`, `"b"`, or `"bit"`, it will imply the base is `"B"` if `prefer_byte` is true; otherwise, imply the base is `"b"`.
///
/// # Examples
///
/// ```
/// # use byte_unit::Unit;
/// let unit = Unit::parse_str("Kib", true, true).unwrap(); // KiB
/// ```
///
/// ```
/// # use byte_unit::Unit;
/// let unit = Unit::parse_str("Kib", false, true).unwrap(); // Kibit
/// ```
pub fn parse_str<S: AsRef<str>>(
s: S,
ignore_case: bool,
prefer_byte: bool,
) -> Result<Self, UnitParseError> {
let s = s.as_ref().trim();
let mut bytes = s.bytes();
read_xib(bytes.next(), bytes, ignore_case, prefer_byte)
}
}
pub(crate) fn read_xib(
e: Option<u8>,
bytes: Bytes,
ignore_case: bool,
prefer_byte: bool,
) -> Result<Unit, UnitParseError> {
match e {
Some(e) => match e.to_ascii_uppercase() {
b'B' => {
let byte = read_b(bytes, if ignore_case { true } else { e == b'B' })?;
if byte {
Ok(Unit::B)
} else {
Ok(Unit::Bit)
}
},
b'K' => {
let (i, byte) = read_ib(bytes, ignore_case, prefer_byte)?;
if i {
if byte {
Ok(Unit::KiB)
} else {
Ok(Unit::Kibit)
}
} else if byte {
Ok(Unit::KB)
} else {
Ok(Unit::Kbit)
}
},
b'M' => {
let (i, byte) = read_ib(bytes, ignore_case, prefer_byte)?;
if i {
if byte {
Ok(Unit::MiB)
} else {
Ok(Unit::Mibit)
}
} else if byte {
Ok(Unit::MB)
} else {
Ok(Unit::Mbit)
}
},
b'G' => {
let (i, byte) = read_ib(bytes, ignore_case, prefer_byte)?;
if i {
if byte {
Ok(Unit::GiB)
} else {
Ok(Unit::Gibit)
}
} else if byte {
Ok(Unit::GB)
} else {
Ok(Unit::Gbit)
}
},
b'T' => {
let (i, byte) = read_ib(bytes, ignore_case, prefer_byte)?;
if i {
if byte {
Ok(Unit::TiB)
} else {
Ok(Unit::Tibit)
}
} else if byte {
Ok(Unit::TB)
} else {
Ok(Unit::Tbit)
}
},
b'P' => {
let (i, byte) = read_ib(bytes, ignore_case, prefer_byte)?;
if i {
if byte {
Ok(Unit::PiB)
} else {
Ok(Unit::Pibit)
}
} else if byte {
Ok(Unit::PB)
} else {
Ok(Unit::Pbit)
}
},
b'E' => {
let (i, byte) = read_ib(bytes, ignore_case, prefer_byte)?;
if i {
if byte {
Ok(Unit::EiB)
} else {
Ok(Unit::Eibit)
}
} else if byte {
Ok(Unit::EB)
} else {
Ok(Unit::Ebit)
}
},
#[cfg(feature = "u128")]
b'Z' => {
let (i, byte) = read_ib(bytes, ignore_case, prefer_byte)?;
if i {
if byte {
Ok(Unit::ZiB)
} else {
Ok(Unit::Zibit)
}
} else if byte {
Ok(Unit::ZB)
} else {
Ok(Unit::Zbit)
}
},
#[cfg(feature = "u128")]
b'Y' => {
let (i, byte) = read_ib(bytes, ignore_case, prefer_byte)?;
if i {
if byte {
Ok(Unit::YiB)
} else {
Ok(Unit::Yibit)
}
} else if byte {
Ok(Unit::YB)
} else {
Ok(Unit::Ybit)
}
},
_ => {
#[cfg(feature = "u128")]
{
Err(UnitParseError {
character: unsafe { get_char_from_bytes(e, bytes) },
expected_characters: &['B', 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y'],
also_expect_no_character: true,
})
}
#[cfg(not(feature = "u128"))]
{
Err(UnitParseError {
character: unsafe { get_char_from_bytes(e, bytes) },
expected_characters: &['B', 'K', 'M', 'G', 'T', 'P', 'E'],
also_expect_no_character: true,
})
}
},
},
None => Ok(if prefer_byte { Unit::B } else { Unit::Bit }),
}
}
fn read_ib(
mut bytes: Bytes,
ignore_case: bool,
default_upper_case: bool,
) -> Result<(bool, bool), UnitParseError> {
match bytes.next() {
Some(mut e) => {
let i = e == b'i' || e == b'I';
if i {
match bytes.next() {
Some(ne) => e = ne,
None => return Ok((true, default_upper_case)),
}
}
match e {
b'b' | b'B' => Ok((i, read_b(bytes, if ignore_case { true } else { e == b'B' })?)),
_ => {
let expected_characters: &[char] = if ignore_case {
if default_upper_case {
&['B']
} else {
&['b']
}
} else {
&['B', 'b']
};
Err(UnitParseError {
character: unsafe { get_char_from_bytes(e, bytes) },
expected_characters,
also_expect_no_character: true,
})
},
}
},
None => Ok((false, default_upper_case)),
}
}
fn read_b(mut bytes: Bytes, byte: bool) -> Result<bool, UnitParseError> {
match bytes.next() {
Some(e) => match e.to_ascii_lowercase() {
b'i' => match bytes.next() {
Some(e) => match e.to_ascii_lowercase() {
b't' => match bytes.next() {
Some(e) => match e.to_ascii_lowercase() {
b's' => match bytes.next() {
Some(e) => Err(UnitParseError {
character: unsafe {
get_char_from_bytes(e, bytes)
},
expected_characters: &[],
also_expect_no_character: true,
}),
None => Ok(false),
},
_ => Err(UnitParseError {
character: unsafe { get_char_from_bytes(e, bytes) },
expected_characters: &['s'],
also_expect_no_character: true,
}),
},
None => Ok(false),
},
_ => Err(UnitParseError {
character: unsafe { get_char_from_bytes(e, bytes) },
expected_characters: &['t'],
also_expect_no_character: false,
}),
},
None => Err(UnitParseError {
character: 'i',
expected_characters: &[],
also_expect_no_character: true,
}),
},
_ => Err(UnitParseError {
character: unsafe { get_char_from_bytes(e, bytes) },
expected_characters: &['i'],
also_expect_no_character: true,
}),
},
None => Ok(byte),
}
}