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Diffstat (limited to 'vendor/encode_unicode/src/traits.rs')
| -rw-r--r-- | vendor/encode_unicode/src/traits.rs | 1014 |
1 files changed, 1014 insertions, 0 deletions
diff --git a/vendor/encode_unicode/src/traits.rs b/vendor/encode_unicode/src/traits.rs new file mode 100644 index 0000000..3f36903 --- /dev/null +++ b/vendor/encode_unicode/src/traits.rs @@ -0,0 +1,1014 @@ +/* Copyright 2016 The encode_unicode Developers + * + * Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or + * http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or + * http://opensource.org/licenses/MIT>, at your option. This file may not be + * copied, modified, or distributed except according to those terms. + */ + +#![allow(unused_unsafe)]// explicit unsafe{} blocks in unsafe functions are a good thing. + +use utf8_char::Utf8Char; +use utf16_char::Utf16Char; +use utf8_iterators::*; +use utf16_iterators::*; +use decoding_iterators::*; +use error::*; +extern crate core; +use self::core::{char, u32, mem}; +use self::core::ops::{Not, Index, RangeFull}; +use self::core::borrow::Borrow; +#[cfg(feature="ascii")] +extern crate ascii; +#[cfg(feature="ascii")] +use self::ascii::AsciiStr; + +// TODO better docs and tests + +/// Methods for working with `u8`s as UTF-8 bytes. +pub trait U8UtfExt { + /// How many more bytes will you need to complete this codepoint? + /// + /// # Errors + /// + /// An error is returned if the byte is not a valid start of an UTF-8 + /// codepoint: + /// + /// * `128..192`: ContinuationByte + /// * `248..`: TooLongSequence + /// + /// Values in 244..248 represent a too high codepoint, but do not cause an + /// error. + fn extra_utf8_bytes(self) -> Result<usize,InvalidUtf8FirstByte>; + + /// How many more bytes will you need to complete this codepoint? + /// + /// This function assumes that the byte is a valid UTF-8 start, and might + /// return any value otherwise. (but the function is pure and safe to call + /// with any value). + fn extra_utf8_bytes_unchecked(self) -> usize; +} + +impl U8UtfExt for u8 { + #[inline] + fn extra_utf8_bytes(self) -> Result<usize,InvalidUtf8FirstByte> { + use error::InvalidUtf8FirstByte::{ContinuationByte,TooLongSeqence}; + // the bit twiddling is explained in extra_utf8_bytes_unchecked() + if self < 128 { + return Ok(0); + } + match ((self as u32)<<25).not().leading_zeros() { + n @ 1...3 => Ok(n as usize), + 0 => Err(ContinuationByte), + _ => Err(TooLongSeqence), + } + } + #[inline] + fn extra_utf8_bytes_unchecked(self) -> usize { + // For fun I've optimized this function (for x86 instruction count): + // The most straightforward implementation, that lets the compiler do + // the optimizing: + //match self { + // 0b0000_0000...0b0111_1111 => 0, + // 0b1100_0010...0b1101_1111 => 1, + // 0b1110_0000...0b1110_1111 => 2, + // 0b1111_0000...0b1111_0100 => 3, + // _ => whatever() + //} + // Using `unsafe{self::core::hint::unreachable_unchecked()}` for the + // "don't care" case is a terrible idea: while having the function + // non-deterministically return whatever happens to be in a register + // MIGHT be acceptable, it permits the function to not `ret`urn at all, + // but let execution fall through to whatever comes after it in the + // binary! (in other words completely UB). + // Currently unreachable_unchecked() might trap too, + // which is certainly not what we want. + // I also think `unsafe{mem::unitialized()}` is much more likely to + // explicitly produce whatever happens to be in a register than tell + // the compiler it can ignore this branch but needs to produce a value. + // + // From the bit patterns we see that for non-ASCII values the result is + // (number of leading set bits) - 1 + // The standard library doesn't have a method for counting leading ones, + // but it has leading_zeros(), which can be used after inverting. + // This function can therefore be reduced to the one-liner + //`self.not().leading_zeros().saturating_sub(1) as usize`, which would + // be branchless for architectures with instructions for + // leading_zeros() and saturating_sub(). + + // Shortest version as long as ASCII-ness can be predicted: (especially + // if the BSR instruction which leading_zeros() uses is microcoded or + // doesn't exist) + // u8.leading_zeros() would cast to a bigger type internally, so that's + // free. compensating by shifting left by 24 before inverting lets the + // compiler know that the value passed to leading_zeros() is not zero, + // for which BSR's output is undefined and leading_zeros() normally has + // special case with a branch. + // Shifting one bit too many left acts as a saturating_sub(1). + if self<128 {0} else {((self as u32)<<25).not().leading_zeros() as usize} + + // Branchless but longer version: (9 instructions) + // It's tempting to try (self|0x80).not().leading_zeros().wrapping_sub(1), + // but that produces high lengths for ASCII values 0b01xx_xxxx. + // If we could somehow (branchlessy) clear that bit for ASCII values... + // We can by masking with the value shifted right with sign extension! + // (any nonzero number of bits in range works) + //let extended = self as i8 as i32; + //let ascii_cleared = (extended<<25) & (extended>>25); + //ascii_cleared.not().leading_zeros() as usize + + // cmov version: (7 instructions) + //(((self as u32)<<24).not().leading_zeros() as usize).saturating_sub(1) + } +} + + +/// Methods for working with `u16`s as UTF-16 units. +pub trait U16UtfExt { + /// Will you need an extra unit to complete this codepoint? + /// + /// Returns `Err` for trailing surrogates, `Ok(true)` for leading surrogates, + /// and `Ok(false)` for others. + fn utf16_needs_extra_unit(self) -> Result<bool,InvalidUtf16FirstUnit>; + + /// Does this `u16` need another `u16` to complete a codepoint? + /// Returns `(self & 0xfc00) == 0xd800` + /// + /// Is basically an unchecked variant of `utf16_needs_extra_unit()`. + fn is_utf16_leading_surrogate(self) -> bool; +} +impl U16UtfExt for u16 { + #[inline] + fn utf16_needs_extra_unit(self) -> Result<bool,InvalidUtf16FirstUnit> { + match self { + // https://en.wikipedia.org/wiki/UTF-16#U.2B10000_to_U.2B10FFFF + 0x00_00...0xd7_ff | 0xe0_00...0xff_ff => Ok(false), + 0xd8_00...0xdb_ff => Ok(true), + _ => Err(InvalidUtf16FirstUnit) + } + } + #[inline] + fn is_utf16_leading_surrogate(self) -> bool { + (self & 0xfc00) == 0xd800// Clear the ten content bytes of a surrogate, + // and see if it's a leading surrogate. + } +} + + + + +/// Extension trait for `char` that adds methods for converting to and from UTF-8 or UTF-16. +pub trait CharExt: Sized { + /// Get the UTF-8 representation of this codepoint. + /// + /// `Utf8Char` is to `[u8;4]` what `char` is to `u32`: + /// a restricted type that cannot be mutated internally. + fn to_utf8(self) -> Utf8Char; + + /// Get the UTF-16 representation of this codepoint. + /// + /// `Utf16Char` is to `[u16;2]` what `char` is to `u32`: + /// a restricted type that cannot be mutated internally. + fn to_utf16(self) -> Utf16Char; + + /// Iterate over or [read](https://doc.rust-lang.org/std/io/trait.Read.html) + /// the one to four bytes in the UTF-8 representation of this codepoint. + /// + /// An identical alternative to the unstable `char.encode_utf8()`. + /// That method somehow still exist on stable, so I have to use a different name. + fn iter_utf8_bytes(self) -> Utf8Iterator; + + /// Iterate over the one or two units in the UTF-16 representation of this codepoint. + /// + /// An identical alternative to the unstable `char.encode_utf16()`. + /// That method somehow still exist on stable, so I have to use a different name. + fn iter_utf16_units(self) -> Utf16Iterator; + + + /// Convert this char to an UTF-8 array, and also return how many bytes of + /// the array are used, + /// + /// The returned array is left-aligned with unused bytes set to zero. + fn to_utf8_array(self) -> ([u8; 4], usize); + + /// Convert this `char` to UTF-16. + /// + /// The second element is non-zero when a surrogate pair is required. + /// + /// # Examples + /// + /// ``` + /// use encode_unicode::CharExt; + /// + /// assert_eq!('@'.to_utf16_array(), ['@' as u16, 0]); + /// assert_eq!('睷'.to_utf16_array(), ['睷' as u16, 0]); + /// assert_eq!('\u{abcde}'.to_utf16_array(), [0xda6f, 0xdcde]); + /// ``` + fn to_utf16_array(self) -> [u16; 2]; + + /// Convert this `char` to UTF-16. + /// The second item is `Some` if a surrogate pair is required. + /// + /// # Examples + /// + /// ``` + /// use encode_unicode::CharExt; + /// + /// assert_eq!('@'.to_utf16_tuple(), ('@' as u16, None)); + /// assert_eq!('睷'.to_utf16_tuple(), ('睷' as u16, None)); + /// assert_eq!('\u{abcde}'.to_utf16_tuple(), (0xda6f, Some(0xdcde))); + /// ``` + fn to_utf16_tuple(self) -> (u16, Option<u16>); + + + + /// Create a `char` from the start of an UTF-8 slice, + /// and also return how many bytes were used. + /// + /// # Errors + /// + /// Returns an `Err` if the slice is empty, doesn't start with a valid + /// UTF-8 sequence or is too short for the sequence. + /// + /// # Examples + /// + /// ``` + /// use encode_unicode::CharExt; + /// use encode_unicode::error::InvalidUtf8Slice::*; + /// use encode_unicode::error::InvalidUtf8::*; + /// + /// assert_eq!(char::from_utf8_slice_start(&[b'A', b'B', b'C']), Ok(('A',1))); + /// assert_eq!(char::from_utf8_slice_start(&[0xdd, 0xbb]), Ok(('\u{77b}',2))); + /// + /// assert_eq!(char::from_utf8_slice_start(&[]), Err(TooShort(1))); + /// assert_eq!(char::from_utf8_slice_start(&[0xf0, 0x99]), Err(TooShort(4))); + /// assert_eq!(char::from_utf8_slice_start(&[0xee, b'F', 0x80]), Err(Utf8(NotAContinuationByte(1)))); + /// assert_eq!(char::from_utf8_slice_start(&[0xee, 0x99, 0x0f]), Err(Utf8(NotAContinuationByte(2)))); + /// ``` + fn from_utf8_slice_start(src: &[u8]) -> Result<(Self,usize),InvalidUtf8Slice>; + + /// Create a `char` from the start of an UTF-16 slice, + /// and also return how many units were used. + /// + /// If you want to continue after an error, continue with the next `u16` unit. + fn from_utf16_slice_start(src: &[u16]) -> Result<(Self,usize), InvalidUtf16Slice>; + + + /// Convert an UTF-8 sequence as returned from `.to_utf8_array()` into a `char` + /// + /// The codepoint must start at the first byte, and leftover bytes are ignored. + /// + /// # Errors + /// + /// Returns an `Err` if the array doesn't start with a valid UTF-8 sequence. + /// + /// # Examples + /// + /// ``` + /// use encode_unicode::CharExt; + /// use encode_unicode::error::InvalidUtf8Array::*; + /// use encode_unicode::error::InvalidUtf8::*; + /// use encode_unicode::error::InvalidCodepoint::*; + /// + /// assert_eq!(char::from_utf8_array([b'A', 0, 0, 0]), Ok('A')); + /// assert_eq!(char::from_utf8_array([0xf4, 0x8b, 0xbb, 0xbb]), Ok('\u{10befb}')); + /// assert_eq!(char::from_utf8_array([b'A', b'B', b'C', b'D']), Ok('A')); + /// assert_eq!(char::from_utf8_array([0, 0, 0xcc, 0xbb]), Ok('\0')); + /// + /// assert_eq!(char::from_utf8_array([0xef, b'F', 0x80, 0x80]), Err(Utf8(NotAContinuationByte(1)))); + /// assert_eq!(char::from_utf8_array([0xc1, 0x80, 0, 0]), Err(Utf8(OverLong))); + /// assert_eq!(char::from_utf8_array([0xf7, 0xaa, 0x99, 0x88]), Err(Codepoint(TooHigh))); + /// ``` + fn from_utf8_array(utf8: [u8; 4]) -> Result<Self,InvalidUtf8Array>; + + /// Convert a UTF-16 pair as returned from `.to_utf16_array()` into a `char`. + /// + /// The second element is ignored when not required. + /// + /// # Examples + /// + /// ``` + /// use encode_unicode::CharExt; + /// use encode_unicode::error::InvalidUtf16Array; + /// + /// assert_eq!(char::from_utf16_array(['x' as u16, 'y' as u16]), Ok('x')); + /// assert_eq!(char::from_utf16_array(['睷' as u16, 0]), Ok('睷')); + /// assert_eq!(char::from_utf16_array([0xda6f, 0xdcde]), Ok('\u{abcde}')); + /// assert_eq!(char::from_utf16_array([0xf111, 0xdbad]), Ok('\u{f111}')); + /// assert_eq!(char::from_utf16_array([0xdaaf, 0xdaaf]), Err(InvalidUtf16Array::SecondIsNotTrailingSurrogate)); + /// assert_eq!(char::from_utf16_array([0xdcac, 0x9000]), Err(InvalidUtf16Array::FirstIsTrailingSurrogate)); + /// ``` + fn from_utf16_array(utf16: [u16; 2]) -> Result<Self, InvalidUtf16Array>; + + /// Convert a UTF-16 pair as returned from `.to_utf16_tuple()` into a `char`. + fn from_utf16_tuple(utf16: (u16, Option<u16>)) -> Result<Self, InvalidUtf16Tuple>; + + + /// Convert an UTF-8 sequence into a char. + /// + /// The length of the slice is taken as length of the sequence; + /// it should be 1,2,3 or 4. + /// + /// # Safety + /// + /// The slice must contain exactly one, valid, UTF-8 sequence. + /// + /// Passing a slice that produces an invalid codepoint is always undefined + /// behavior; Later checks that the codepoint is valid can be removed + /// by the compiler. + /// + /// # Panics + /// + /// If the slice is empty + unsafe fn from_utf8_exact_slice_unchecked(src: &[u8]) -> Self; + + /// Convert a UTF-16 array as returned from `.to_utf16_array()` into a + /// `char`. + /// + /// This function is safe because it avoids creating invalid codepoints, + /// but the returned value might not be what one expectedd. + /// + /// # Examples + /// + /// ``` + /// use encode_unicode::CharExt; + /// + /// // starts with a trailing surrogate - converted as if it was a valid + /// // surrogate pair anyway. + /// assert_eq!(char::from_utf16_array_unchecked([0xdbad, 0xf19e]), '\u{fb59e}'); + /// // missing trailing surrogate - ditto + /// assert_eq!(char::from_utf16_array_unchecked([0xd802, 0]), '\u{10800}'); + /// ``` + fn from_utf16_array_unchecked(utf16: [u16;2]) -> Self; + + /// Convert a UTF-16 tuple as returned from `.to_utf16_tuple()` into a `char`. + unsafe fn from_utf16_tuple_unchecked(utf16: (u16, Option<u16>)) -> Self; + + + /// Produces more detailed errors than `char::from_u32()` + /// + /// # Errors + /// + /// This function will return an error if + /// + /// * the value is greater than 0x10ffff + /// * the value is between 0xd800 and 0xdfff (inclusive) + /// + /// # Examples + /// + /// ``` + /// use encode_unicode::CharExt; + /// use encode_unicode::error::InvalidCodepoint; + /// + /// assert_eq!(char::from_u32_detailed(0x41), Ok('A')); + /// assert_eq!(char::from_u32_detailed(0x40_00_00), Err(InvalidCodepoint::TooHigh)); + /// assert_eq!(char::from_u32_detailed(0xd951), Err(InvalidCodepoint::Utf16Reserved)); + /// assert_eq!(char::from_u32_detailed(0xdddd), Err(InvalidCodepoint::Utf16Reserved)); + /// assert_eq!(char::from_u32_detailed(0xdd), Ok('Ý')); + /// assert_eq!(char::from_u32_detailed(0x1f331), Ok('🌱')); + /// ``` + fn from_u32_detailed(c: u32) -> Result<Self,InvalidCodepoint>; +} + + + +impl CharExt for char { + ///////// + //UTF-8// + ///////// + + fn to_utf8(self) -> Utf8Char { + self.into() + } + fn iter_utf8_bytes(self) -> Utf8Iterator { + self.to_utf8().into_iter() + } + + fn to_utf8_array(self) -> ([u8; 4], usize) { + let len = self.len_utf8(); + let mut c = self as u32; + if len == 1 {// ASCII, the common case + ([c as u8, 0, 0, 0], 1) + } else { + let mut parts = 0;// convert to 6-bit bytes + parts |= c & 0x3f; c>>=6; + parts<<=8; parts |= c & 0x3f; c>>=6; + parts<<=8; parts |= c & 0x3f; c>>=6; + parts<<=8; parts |= c & 0x3f; + parts |= 0x80_80_80_80;// set the most significant bit + parts >>= 8*(4-len);// right-align bytes + // Now, unused bytes are zero, (which matters for Utf8Char.eq()) + // and the rest are 0b10xx_xxxx + + // set header on first byte + parts |= (0xff_00u32 >> len) & 0xff;// store length + parts &= Not::not(1u32 << 7-len);// clear the next bit after it + + let bytes: [u8; 4] = unsafe{ mem::transmute(u32::from_le(parts)) }; + (bytes, len) + } + } + + + fn from_utf8_slice_start(src: &[u8]) -> Result<(Self,usize),InvalidUtf8Slice> { + use errors::InvalidUtf8::*; + use errors::InvalidUtf8Slice::*; + let first = match src.first() { + Some(first) => *first, + None => return Err(TooShort(1)), + }; + let bytes = match first.extra_utf8_bytes() { + Err(e) => return Err(Utf8(FirstByte(e))), + Ok(0) => return Ok((first as char, 1)), + Ok(extra) if extra >= src.len() + => return Err(TooShort(extra+1)), + Ok(extra) => &src[..extra+1], + }; + if let Some(i) = bytes.iter().skip(1).position(|&b| (b >> 6) != 0b10 ) { + Err(Utf8(NotAContinuationByte(i+1))) + } else if overlong(bytes[0], bytes[1]) { + Err(Utf8(OverLong)) + } else { + match char::from_u32_detailed(merge_nonascii_unchecked_utf8(bytes)) { + Ok(c) => Ok((c, bytes.len())), + Err(e) => Err(Codepoint(e)), + } + } + } + + fn from_utf8_array(utf8: [u8; 4]) -> Result<Self,InvalidUtf8Array> { + use errors::InvalidUtf8::*; + use errors::InvalidUtf8Array::*; + let src = match utf8[0].extra_utf8_bytes() { + Err(error) => return Err(Utf8(FirstByte(error))), + Ok(0) => return Ok(utf8[0] as char), + Ok(extra) => &utf8[..extra+1], + }; + if let Some(i) = src[1..].iter().position(|&b| (b >> 6) != 0b10 ) { + Err(Utf8(NotAContinuationByte(i+1))) + } else if overlong(utf8[0], utf8[1]) { + Err(Utf8(OverLong)) + } else { + char::from_u32_detailed(merge_nonascii_unchecked_utf8(src)) + .map_err(|e| Codepoint(e) ) + } + } + + unsafe fn from_utf8_exact_slice_unchecked(src: &[u8]) -> Self { + if src.len() == 1 { + src[0] as char + } else { + char::from_u32_unchecked(merge_nonascii_unchecked_utf8(src)) + } + } + + + + ////////// + //UTF-16// + ////////// + + fn to_utf16(self) -> Utf16Char { + Utf16Char::from(self) + } + fn iter_utf16_units(self) -> Utf16Iterator { + self.to_utf16().into_iter() + } + + fn to_utf16_array(self) -> [u16;2] { + let (first, second) = self.to_utf16_tuple(); + [first, second.unwrap_or(0)] + } + fn to_utf16_tuple(self) -> (u16, Option<u16>) { + if self <= '\u{ffff}' {// single + (self as u16, None) + } else {// double + let c = self as u32 - 0x_01_00_00; + let high = 0x_d8_00 + (c >> 10); + let low = 0x_dc_00 + (c & 0x_03_ff); + (high as u16, Some(low as u16)) + } + } + + + fn from_utf16_slice_start(src: &[u16]) -> Result<(Self,usize), InvalidUtf16Slice> { + use errors::InvalidUtf16Slice::*; + unsafe {match (src.get(0), src.get(1)) { + (Some(&u @ 0x00_00...0xd7_ff), _) | + (Some(&u @ 0xe0_00...0xff_ff), _) + => Ok((char::from_u32_unchecked(u as u32), 1)), + (Some(&0xdc_00...0xdf_ff), _) => Err(FirstLowSurrogate), + (None, _) => Err(EmptySlice), + (Some(&f @ 0xd8_00...0xdb_ff), Some(&s @ 0xdc_00...0xdf_ff)) + => Ok((char::from_utf16_tuple_unchecked((f, Some(s))), 2)), + (Some(&0xd8_00...0xdb_ff), Some(_)) => Err(SecondNotLowSurrogate), + (Some(&0xd8_00...0xdb_ff), None) => Err(MissingSecond), + (Some(_), _) => unreachable!() + }} + } + + fn from_utf16_array(utf16: [u16;2]) -> Result<Self, InvalidUtf16Array> { + use errors::InvalidUtf16Array::*; + if let Some(c) = char::from_u32(utf16[0] as u32) { + Ok(c) // single + } else if utf16[0] < 0xdc_00 && utf16[1] & 0xfc_00 == 0xdc_00 { + // correct surrogate pair + Ok(combine_surrogates(utf16[0], utf16[1])) + } else if utf16[0] < 0xdc_00 { + Err(SecondIsNotTrailingSurrogate) + } else { + Err(FirstIsTrailingSurrogate) + } + } + fn from_utf16_tuple(utf16: (u16, Option<u16>)) -> Result<Self, InvalidUtf16Tuple> { + use errors::InvalidUtf16Tuple::*; + unsafe{ match utf16 { + (0x00_00...0xd7_ff, None) | // single + (0xe0_00...0xff_ff, None) | // single + (0xd8_00...0xdb_ff, Some(0xdc_00...0xdf_ff)) // correct surrogate + => Ok(char::from_utf16_tuple_unchecked(utf16)), + (0xd8_00...0xdb_ff, Some(_)) => Err(InvalidSecond), + (0xd8_00...0xdb_ff, None ) => Err(MissingSecond), + (0xdc_00...0xdf_ff, _ ) => Err(FirstIsTrailingSurrogate), + ( _ , Some(_)) => Err(SuperfluousSecond), + ( _ , None ) => unreachable!() + }} + } + + fn from_utf16_array_unchecked(utf16: [u16;2]) -> Self { + // treat any array with a surrogate value in [0] as a surrogate because + // combine_surrogates() is safe. + // `(utf16[0] & 0xf800) == 0xd80` might not be quite as fast as + // `utf16[1] != 0`, but avoiding the potential for UB is worth it + // since the conversion isn't zero-cost in either case. + char::from_u32(utf16[0] as u32) + .unwrap_or_else(|| combine_surrogates(utf16[0], utf16[1]) ) + } + unsafe fn from_utf16_tuple_unchecked(utf16: (u16, Option<u16>)) -> Self { + match utf16.1 { + Some(second) => combine_surrogates(utf16.0, second), + None => char::from_u32_unchecked(utf16.0 as u32) + } + } + + + fn from_u32_detailed(c: u32) -> Result<Self,InvalidCodepoint> { + match char::from_u32(c) { + Some(c) => Ok(c), + None if c > 0x10_ff_ff => Err(InvalidCodepoint::TooHigh), + None => Err(InvalidCodepoint::Utf16Reserved), + } + } +} + +// Adapted from https://www.cl.cam.ac.uk/~mgk25/ucs/utf8_check.c +fn overlong(first: u8, second: u8) -> bool { + if first < 0x80 { + false + } else if (first & 0xe0) == 0xc0 { + (first & 0xfe) == 0xc0 + } else if (first & 0xf0) == 0xe0 { + first == 0xe0 && (second & 0xe0) == 0x80 + } else { + first == 0xf0 && (second & 0xf0) == 0x80 + } +} + +/// Decodes the codepoint represented by a multi-byte UTF-8 sequence. +/// +/// Does not check that the codepoint is valid, +/// and returns `u32` because casting invalid codepoints to `char` is insta UB. +fn merge_nonascii_unchecked_utf8(src: &[u8]) -> u32 { + let mut c = src[0] as u32 & (0x7f >> src.len()); + for b in &src[1..] { + c = (c << 6) | (b & 0b0011_1111) as u32; + } + c +} + +/// Create a `char` from a leading and a trailing surrogate. +/// +/// This function is safe because it ignores the six most significant bits of +/// each arguments and always produces a codepoint in 0x01_00_00..=0x10_ff_ff. +fn combine_surrogates(first: u16, second: u16) -> char { + unsafe { + let high = (first & 0x_03_ff) as u32; + let low = (second & 0x_03_ff) as u32; + let c = ((high << 10) | low) + 0x_01_00_00; // no, the constant can't be or'd in + char::from_u32_unchecked(c) + } +} + + + +/// Adds `.utf8chars()` and `.utf16chars()` iterator constructors to `&str`. +pub trait StrExt: AsRef<str> { + /// Equivalent to `.chars()` but produces `Utf8Char`s. + fn utf8chars(&self) -> Utf8Chars; + /// Equivalent to `.chars()` but produces `Utf16Char`s. + fn utf16chars(&self) -> Utf16Chars; + /// Equivalent to `.char_indices()` but produces `Utf8Char`s. + fn utf8char_indices(&self) -> Utf8CharIndices; + /// Equivalent to `.char_indices()` but produces `Utf16Char`s. + fn utf16char_indices(&self) -> Utf16CharIndices; +} + +impl StrExt for str { + fn utf8chars(&self) -> Utf8Chars { + Utf8Chars::from(self) + } + fn utf16chars(&self) -> Utf16Chars { + Utf16Chars::from(self) + } + fn utf8char_indices(&self) -> Utf8CharIndices { + Utf8CharIndices::from(self) + } + fn utf16char_indices(&self) -> Utf16CharIndices { + Utf16CharIndices::from(self) + } +} + +#[cfg(feature="ascii")] +impl StrExt for AsciiStr { + fn utf8chars(&self) -> Utf8Chars { + Utf8Chars::from(self.as_str()) + } + fn utf16chars(&self) -> Utf16Chars { + Utf16Chars::from(self.as_str()) + } + fn utf8char_indices(&self) -> Utf8CharIndices { + Utf8CharIndices::from(self.as_str()) + } + fn utf16char_indices(&self) -> Utf16CharIndices { + Utf16CharIndices::from(self.as_str()) + } +} + + + +/// Iterator methods that convert between `u8`s and `Utf8Char` or `u16`s and `Utf16Char` +/// +/// All the iterator adapters also accept iterators that produce references of +/// the type they convert from. +pub trait IterExt: Iterator+Sized { + /// Converts an iterator of `Utf8Char`s or `&Utf8Char`s to an iterator of + /// `u8`s. + /// + /// Has the same effect as `.flat_map()` or `.flatten()`, but the returned + /// iterator is ~40% faster. + /// + /// The iterator also implements `Read` + /// (when the `std` feature isn't disabled). + /// Reading will never produce an error, and calls to `.read()` and `.next()` + /// can be mixed. + /// + /// The exact number of bytes cannot be known in advance, but `size_hint()` + /// gives the possible range. + /// (min: all remaining characters are ASCII, max: all require four bytes) + /// + /// # Examples + /// + /// From iterator of values: + /// + /// ``` + /// use encode_unicode::{IterExt, StrExt}; + /// + /// let iterator = "foo".utf8chars(); + /// let mut bytes = [0; 4]; + /// for (u,dst) in iterator.to_bytes().zip(&mut bytes) {*dst=u;} + /// assert_eq!(&bytes, b"foo\0"); + /// ``` + /// + /// From iterator of references: + /// + #[cfg_attr(feature="std", doc=" ```")] + #[cfg_attr(not(feature="std"), doc=" ```no_compile")] + /// use encode_unicode::{IterExt, StrExt, Utf8Char}; + /// + /// let chars: Vec<Utf8Char> = "💣 bomb 💣".utf8chars().collect(); + /// let bytes: Vec<u8> = chars.iter().to_bytes().collect(); + /// let flat_map: Vec<u8> = chars.iter().flat_map(|u8c| *u8c ).collect(); + /// assert_eq!(bytes, flat_map); + /// ``` + /// + /// `Read`ing from it: + /// + #[cfg_attr(feature="std", doc=" ```")] + #[cfg_attr(not(feature="std"), doc=" ```no_compile")] + /// use encode_unicode::{IterExt, StrExt}; + /// use std::io::Read; + /// + /// let s = "Ååh‽"; + /// assert_eq!(s.len(), 8); + /// let mut buf = [b'E'; 9]; + /// let mut reader = s.utf8chars().to_bytes(); + /// assert_eq!(reader.read(&mut buf[..]).unwrap(), 8); + /// assert_eq!(reader.read(&mut buf[..]).unwrap(), 0); + /// assert_eq!(&buf[..8], s.as_bytes()); + /// assert_eq!(buf[8], b'E'); + /// ``` + fn to_bytes(self) -> Utf8CharSplitter<Self::Item,Self> where Self::Item: Borrow<Utf8Char>; + + /// Converts an iterator of `Utf16Char` (or `&Utf16Char`) to an iterator of + /// `u16`s. + /// + /// Has the same effect as `.flat_map()` or `.flatten()`, but the returned + /// iterator is about twice as fast. + /// + /// The exact number of units cannot be known in advance, but `size_hint()` + /// gives the possible range. + /// + /// # Examples + /// + /// From iterator of values: + /// + /// ``` + /// use encode_unicode::{IterExt, StrExt}; + /// + /// let iterator = "foo".utf16chars(); + /// let mut units = [0; 4]; + /// for (u,dst) in iterator.to_units().zip(&mut units) {*dst=u;} + /// + /// assert_eq!(units, ['f' as u16, 'o' as u16, 'o' as u16, 0]); + /// ``` + /// + /// From iterator of references: + /// + #[cfg_attr(feature="std", doc=" ```")] + #[cfg_attr(not(feature="std"), doc=" ```no_compile")] + /// use encode_unicode::{IterExt, StrExt, Utf16Char}; + /// + /// // (💣 takes two units) + /// let chars: Vec<Utf16Char> = "💣 bomb 💣".utf16chars().collect(); + /// let units: Vec<u16> = chars.iter().to_units().collect(); + /// let flat_map: Vec<u16> = chars.iter().flat_map(|u16c| *u16c ).collect(); + /// + /// assert_eq!(units, flat_map); + /// ``` + fn to_units(self) -> Utf16CharSplitter<Self::Item,Self> where Self::Item: Borrow<Utf16Char>; + + /// Decodes bytes as UTF-8 and groups them into `Utf8Char`s + /// + /// When errors (invalid values or sequences) are encountered, + /// it continues with the byte right after the start of the error sequence. + /// This is neither the most intelligent choiche (sometimes it is guaranteed to + /// produce another error), nor the easiest to implement, but I believe it to + /// be the most predictable. + /// It also means that ASCII characters are never hidden by errors. + /// + /// # Examples + /// + /// Replace all errors with u+FFFD REPLACEMENT_CHARACTER: + /// ``` + /// use encode_unicode::{Utf8Char, IterExt}; + /// + /// let mut buf = [b'\0'; 255]; + /// let len = b"foo\xCFbar".iter() + /// .to_utf8chars() + /// .flat_map(|r| r.unwrap_or(Utf8Char::from('\u{FFFD}')).into_iter() ) + /// .zip(&mut buf[..]) + /// .map(|(byte, dst)| *dst = byte ) + /// .count(); + /// + /// assert_eq!(&buf[..len], "foo\u{FFFD}bar".as_bytes()); + /// ``` + /// + /// Collect everything up until the first error into a string: + #[cfg_attr(feature="std", doc=" ```")] + #[cfg_attr(not(feature="std"), doc=" ```no_compile")] + /// use encode_unicode::iterator::Utf8CharMerger; + /// let mut good = String::new(); + /// for r in Utf8CharMerger::from(b"foo\xcc\xbbbar\xcc\xddbaz") { + /// if let Ok(uc) = r { + /// good.push_str(uc.as_str()); + /// } else { + /// break; + /// } + /// } + /// assert_eq!(good, "foo̻bar"); + /// ``` + /// + /// Abort decoding on error: + #[cfg_attr(feature="std", doc=" ```")] + #[cfg_attr(not(feature="std"), doc=" ```no_compile")] + /// use encode_unicode::{IterExt, Utf8Char}; + /// use encode_unicode::error::{InvalidUtf8Slice, InvalidUtf8}; + /// + /// let result = b"ab\0\xe0\xbc\xa9 \xf3\x80\x77".iter() + /// .to_utf8chars() + /// .collect::<Result<String,InvalidUtf8Slice>>(); + /// + /// assert_eq!(result, Err(InvalidUtf8Slice::Utf8(InvalidUtf8::NotAContinuationByte(2)))); + /// ``` + fn to_utf8chars(self) -> Utf8CharMerger<Self::Item,Self> where Self::Item: Borrow<u8>; + + /// Decodes bytes as UTF-16 and groups them into `Utf16Char`s + /// + /// When errors (unmatched leading surrogates or unexpected trailing surrogates) + /// are encountered, an error is produced for every unit. + /// + /// # Examples + /// + /// Replace errors with '�': + #[cfg_attr(feature="std", doc=" ```")] + #[cfg_attr(not(feature="std"), doc=" ```no_compile")] + /// use encode_unicode::{IterExt, Utf16Char}; + /// + /// let slice = &['a' as u16, 0xdf00, 0xd83c, 0xdca0][..]; + /// let string = slice.iter() + /// .to_utf16chars() + /// .map(|r| r.unwrap_or(Utf16Char::from('\u{fffd}')) ) // REPLACEMENT_CHARACTER + /// .collect::<String>(); + /// + /// assert_eq!(string, "a�🂠"); + /// ``` + /// + /// ``` + /// use encode_unicode::{IterExt, Utf16Char}; + /// use encode_unicode::error::Utf16PairError::*; + /// + /// let slice = [0xdcba, 0xdeff, 0xd8be, 0xdeee, 'Y' as u16, 0xdab1, 0xdab1]; + /// let mut iter = slice.iter().to_utf16chars(); + /// assert_eq!(iter.size_hint(), (3, Some(7))); + /// assert_eq!(iter.next(), Some(Err(UnexpectedTrailingSurrogate))); + /// assert_eq!(iter.next(), Some(Err(UnexpectedTrailingSurrogate))); + /// assert_eq!(iter.next(), Some(Ok(Utf16Char::from('\u{3faee}')))); + /// assert_eq!(iter.next(), Some(Ok(Utf16Char::from('Y')))); + /// assert_eq!(iter.next(), Some(Err(UnmatchedLeadingSurrogate))); + /// assert_eq!(iter.next(), Some(Err(Incomplete))); + /// assert_eq!(iter.into_remaining_units().next(), None); + /// ``` + /// + /// Search for a codepoint and return the codepoint index of the first match: + /// ``` + /// use encode_unicode::{IterExt, Utf16Char}; + /// + /// let position = [0xd875, 0xdd4f, '≈' as u16, '2' as u16].iter() + /// .to_utf16chars() + /// .position(|r| r == Ok(Utf16Char::from('≈')) ); + /// + /// assert_eq!(position, Some(1)); + /// ``` + fn to_utf16chars(self) -> Utf16CharMerger<Self::Item,Self> where Self::Item: Borrow<u16>; +} + +impl<I:Iterator> IterExt for I { + fn to_bytes(self) -> Utf8CharSplitter<Self::Item,Self> where Self::Item: Borrow<Utf8Char> { + iter_bytes(self) + } + fn to_units(self) -> Utf16CharSplitter<Self::Item,Self> where Self::Item: Borrow<Utf16Char> { + iter_units(self) + } + fn to_utf8chars(self) -> Utf8CharMerger<Self::Item,Self> where Self::Item: Borrow<u8> { + Utf8CharMerger::from(self) + } + fn to_utf16chars(self) -> Utf16CharMerger<Self::Item,Self> where Self::Item: Borrow<u16> { + Utf16CharMerger::from(self) + } +} + + +/// Methods for iterating over `u8` and `u16` slices as UTF-8 or UTF-16 characters. +/// +/// The iterators are slightly faster than the similar methods in [`IterExt`](trait.IterExt.html) +/// because they con "push back" items for free after errors and don't need a +/// separate buffer that must be checked on every call to `.next()`. +pub trait SliceExt: Index<RangeFull> { + /// Decode `u8` slices as UTF-8 and iterate over the codepoints as `Utf8Char`s, + /// + /// # Examples + /// + /// Get the index and error type of the first error: + #[cfg_attr(feature="std", doc=" ```")] + #[cfg_attr(not(feature="std"), doc=" ```no_compile")] + /// use encode_unicode::{SliceExt, Utf8Char}; + /// use encode_unicode::error::InvalidUtf8Slice; + /// + /// let slice = b"ab\0\xe0\xbc\xa9 \xf3\x80\x77"; + /// let result = slice.utf8char_indices() + /// .map(|(offset,r,length)| r.map_err(|e| (offset,e,length) ) ) + /// .collect::<Result<String,(usize,InvalidUtf8Slice,usize)>>(); + /// + /// assert_eq!(result, Err((7, InvalidUtf8Slice::TooShort(4), 1))); + /// ``` + /// + /// ``` + /// use encode_unicode::{SliceExt, Utf8Char}; + /// use std::error::Error; + /// + /// let slice = b"\xf0\xbf\xbf\xbfXY\xdd\xbb\xe1\x80\x99quux123"; + /// let mut fixed_size = [Utf8Char::default(); 8]; + /// for (cp_i, (byte_index, r, _)) in slice.utf8char_indices().enumerate().take(8) { + /// match r { + /// Ok(u8c) => fixed_size[cp_i] = u8c, + /// Err(e) => panic!("Invalid codepoint at index {} ({})", cp_i, e.description()), + /// } + /// } + /// let chars = ['\u{3ffff}', 'X', 'Y', '\u{77b}', '\u{1019}', 'q', 'u', 'u']; + /// assert_eq!(fixed_size, chars); + /// ``` + /// + #[cfg_attr(feature="std", doc=" ```")] + #[cfg_attr(not(feature="std"), doc=" ```no_compile")] + /// use encode_unicode::{SliceExt, Utf8Char}; + /// use encode_unicode::error::InvalidUtf8Slice::*; + /// use encode_unicode::error::{InvalidUtf8, InvalidUtf8FirstByte, InvalidCodepoint}; + /// + /// let bytes = b"\xfa-\xf4\x8f\xee\xa1\x8f-\xed\xa9\x87\xf0\xcc\xbb"; + /// let mut errors = Vec::new(); + /// let mut lengths = Vec::new(); + /// let mut string = String::new(); + /// for (offset,result,length) in bytes.utf8char_indices() { + /// lengths.push((offset,length)); + /// let c = result.unwrap_or_else(|error| { + /// errors.push((offset,error)); + /// Utf8Char::from('\u{fffd}') // replacement character + /// }); + /// string.push_str(c.as_str()); + /// } + /// + /// assert_eq!(string, "�-��\u{e84f}-����\u{33b}"); + /// assert_eq!(lengths, [(0,1), (1,1), (2,1), (3,1), (4,3), (7,1), + /// (8,1), (9,1), (10,1), (11,1), (12,2)]); + /// assert_eq!(errors, [ + /// ( 0, Utf8(InvalidUtf8::FirstByte(InvalidUtf8FirstByte::TooLongSeqence))), + /// ( 2, Utf8(InvalidUtf8::NotAContinuationByte(2))), + /// ( 3, Utf8(InvalidUtf8::FirstByte(InvalidUtf8FirstByte::ContinuationByte))), + /// ( 8, Codepoint(InvalidCodepoint::Utf16Reserved)), + /// ( 9, Utf8(InvalidUtf8::FirstByte(InvalidUtf8FirstByte::ContinuationByte))), + /// (10, Utf8(InvalidUtf8::FirstByte(InvalidUtf8FirstByte::ContinuationByte))), + /// (11, TooShort(4)), // (but it was not the last element returned!) + /// ]); + /// ``` + fn utf8char_indices(&self) -> Utf8CharDecoder where Self::Output: Borrow<[u8]>; + + + /// Decode `u16` slices as UTF-16 and iterate over the codepoints as `Utf16Char`s, + /// + /// The iterator produces `(usize,Result<Utf16Char,Utf16Error>,usize)`, + /// and the slice is validated as you go. + /// + /// The first `usize` contains the offset from the start of the slice and + /// the last `usize` contains the length of the codepoint or error. + /// The length is either 1 or 2, and always 1 for errors. + /// + /// # Examples + /// + #[cfg_attr(feature="std", doc=" ```")] + #[cfg_attr(not(feature="std"), doc=" ```no_compile")] + /// use encode_unicode::{SliceExt, Utf8Char}; + /// + /// let slice = &['a' as u16, 0xdf00, 0xd83c, 0xdca0][..]; + /// let mut errors = Vec::new(); + /// let string = slice.utf16char_indices().map(|(offset,r,_)| match r { + /// Ok(u16c) => Utf8Char::from(u16c), + /// Err(_) => { + /// errors.push(offset); + /// Utf8Char::from('\u{fffd}') // REPLACEMENT_CHARACTER + /// } + /// }).collect::<String>(); + /// + /// assert_eq!(string, "a�🂠"); + /// assert_eq!(errors, [1]); + /// ``` + /// + /// Search for a codepoint and return its unit and codepoint index. + /// ``` + /// use encode_unicode::{SliceExt, Utf16Char}; + /// + /// let slice = [0xd875,/*'𝕏'*/ 0xdd4f, '≈' as u16, '2' as u16]; + /// let position = slice.utf16char_indices() + /// .enumerate() + /// .find(|&(_,(_,r,_))| r == Ok(Utf16Char::from('≈')) ) + /// .map(|(codepoint, (offset, _, _))| (codepoint, offset) ); + /// + /// assert_eq!(position, Some((1,2))); + /// ``` + /// + /// Error types: + /// ``` + /// use encode_unicode::{SliceExt, Utf16Char}; + /// use encode_unicode::error::Utf16PairError::*; + /// + /// let slice = [0xdcba, 0xdeff, 0xd8be, 0xdeee, 'λ' as u16, 0xdab1, 0xdab1]; + /// let mut iter = slice.utf16char_indices(); + /// assert_eq!(iter.next(), Some((0, Err(UnexpectedTrailingSurrogate), 1))); + /// assert_eq!(iter.next(), Some((1, Err(UnexpectedTrailingSurrogate), 1))); + /// assert_eq!(iter.next(), Some((2, Ok(Utf16Char::from('\u{3faee}')), 2))); + /// assert_eq!(iter.next(), Some((4, Ok(Utf16Char::from('λ')), 1))); + /// assert_eq!(iter.next(), Some((5, Err(UnmatchedLeadingSurrogate), 1))); + /// assert_eq!(iter.next(), Some((6, Err(Incomplete), 1))); + /// assert_eq!(iter.next(), None); + /// assert_eq!(iter.as_slice(), []) + /// ``` + fn utf16char_indices(&self) -> Utf16CharDecoder where Self::Output: Borrow<[u16]>; +} + +impl<S: ?Sized+Index<RangeFull>> SliceExt for S { + fn utf8char_indices(&self) -> Utf8CharDecoder where Self::Output: Borrow<[u8]> { + Utf8CharDecoder::from(self[..].borrow()) + } + fn utf16char_indices(&self) -> Utf16CharDecoder where Self::Output: Borrow<[u16]> { + Utf16CharDecoder::from(self[..].borrow()) + } +} |