| // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.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. |
| |
| //! Character manipulation. |
| //! |
| //! For more details, see ::rustc_unicode::char (a.k.a. std::char) |
| |
| #![allow(non_snake_case)] |
| #![stable(feature = "core_char", since = "1.2.0")] |
| |
| use prelude::v1::*; |
| |
| use mem::transmute; |
| |
| // UTF-8 ranges and tags for encoding characters |
| const TAG_CONT: u8 = 0b1000_0000; |
| const TAG_TWO_B: u8 = 0b1100_0000; |
| const TAG_THREE_B: u8 = 0b1110_0000; |
| const TAG_FOUR_B: u8 = 0b1111_0000; |
| const MAX_ONE_B: u32 = 0x80; |
| const MAX_TWO_B: u32 = 0x800; |
| const MAX_THREE_B: u32 = 0x10000; |
| |
| /* |
| Lu Uppercase_Letter an uppercase letter |
| Ll Lowercase_Letter a lowercase letter |
| Lt Titlecase_Letter a digraphic character, with first part uppercase |
| Lm Modifier_Letter a modifier letter |
| Lo Other_Letter other letters, including syllables and ideographs |
| Mn Nonspacing_Mark a nonspacing combining mark (zero advance width) |
| Mc Spacing_Mark a spacing combining mark (positive advance width) |
| Me Enclosing_Mark an enclosing combining mark |
| Nd Decimal_Number a decimal digit |
| Nl Letter_Number a letterlike numeric character |
| No Other_Number a numeric character of other type |
| Pc Connector_Punctuation a connecting punctuation mark, like a tie |
| Pd Dash_Punctuation a dash or hyphen punctuation mark |
| Ps Open_Punctuation an opening punctuation mark (of a pair) |
| Pe Close_Punctuation a closing punctuation mark (of a pair) |
| Pi Initial_Punctuation an initial quotation mark |
| Pf Final_Punctuation a final quotation mark |
| Po Other_Punctuation a punctuation mark of other type |
| Sm Math_Symbol a symbol of primarily mathematical use |
| Sc Currency_Symbol a currency sign |
| Sk Modifier_Symbol a non-letterlike modifier symbol |
| So Other_Symbol a symbol of other type |
| Zs Space_Separator a space character (of various non-zero widths) |
| Zl Line_Separator U+2028 LINE SEPARATOR only |
| Zp Paragraph_Separator U+2029 PARAGRAPH SEPARATOR only |
| Cc Control a C0 or C1 control code |
| Cf Format a format control character |
| Cs Surrogate a surrogate code point |
| Co Private_Use a private-use character |
| Cn Unassigned a reserved unassigned code point or a noncharacter |
| */ |
| |
| /// The highest valid code point a `char` can have. |
| /// |
| /// A [`char`] is a [Unicode Scalar Value], which means that it is a [Code |
| /// Point], but only ones within a certain range. `MAX` is the highest valid |
| /// code point that's a valid [Unicode Scalar Value]. |
| /// |
| /// [`char`]: ../../std/primitive.char.html |
| /// [Unicode Scalar Value]: http://www.unicode.org/glossary/#unicode_scalar_value |
| /// [Code Point]: http://www.unicode.org/glossary/#code_point |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub const MAX: char = '\u{10ffff}'; |
| |
| /// Converts a `u32` to a `char`. |
| /// |
| /// Note that all [`char`]s are valid [`u32`]s, and can be casted to one with |
| /// [`as`]: |
| /// |
| /// ``` |
| /// let c = '💯'; |
| /// let i = c as u32; |
| /// |
| /// assert_eq!(128175, i); |
| /// ``` |
| /// |
| /// However, the reverse is not true: not all valid [`u32`]s are valid |
| /// [`char`]s. `from_u32()` will return `None` if the input is not a valid value |
| /// for a [`char`]. |
| /// |
| /// [`char`]: ../../std/primitive.char.html |
| /// [`u32`]: ../../std/primitive.u32.html |
| /// [`as`]: ../../book/casting-between-types.html#as |
| /// |
| /// For an unsafe version of this function which ignores these checks, see |
| /// [`from_u32_unchecked()`]. |
| /// |
| /// [`from_u32_unchecked()`]: fn.from_u32_unchecked.html |
| /// |
| /// # Examples |
| /// |
| /// Basic usage: |
| /// |
| /// ``` |
| /// use std::char; |
| /// |
| /// let c = char::from_u32(0x2764); |
| /// |
| /// assert_eq!(Some('❤'), c); |
| /// ``` |
| /// |
| /// Returning `None` when the input is not a valid [`char`]: |
| /// |
| /// ``` |
| /// use std::char; |
| /// |
| /// let c = char::from_u32(0x110000); |
| /// |
| /// assert_eq!(None, c); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn from_u32(i: u32) -> Option<char> { |
| // catch out-of-bounds and surrogates |
| if (i > MAX as u32) || (i >= 0xD800 && i <= 0xDFFF) { |
| None |
| } else { |
| Some(unsafe { from_u32_unchecked(i) }) |
| } |
| } |
| |
| /// Converts a `u32` to a `char`, ignoring validity. |
| /// |
| /// Note that all [`char`]s are valid [`u32`]s, and can be casted to one with |
| /// [`as`]: |
| /// |
| /// ``` |
| /// let c = '💯'; |
| /// let i = c as u32; |
| /// |
| /// assert_eq!(128175, i); |
| /// ``` |
| /// |
| /// However, the reverse is not true: not all valid [`u32`]s are valid |
| /// [`char`]s. `from_u32_unchecked()` will ignore this, and blindly cast to |
| /// [`char`], possibly creating an invalid one. |
| /// |
| /// [`char`]: ../../std/primitive.char.html |
| /// [`u32`]: ../../std/primitive.u32.html |
| /// [`as`]: ../../book/casting-between-types.html#as |
| /// |
| /// # Safety |
| /// |
| /// This function is unsafe, as it may construct invalid `char` values. |
| /// |
| /// For a safe version of this function, see the [`from_u32()`] function. |
| /// |
| /// [`from_u32()`]: fn.from_u32.html |
| /// |
| /// # Examples |
| /// |
| /// Basic usage: |
| /// |
| /// ``` |
| /// use std::char; |
| /// |
| /// let c = unsafe { char::from_u32_unchecked(0x2764) }; |
| /// |
| /// assert_eq!('❤', c); |
| /// ``` |
| #[inline] |
| #[stable(feature = "char_from_unchecked", since = "1.5.0")] |
| pub unsafe fn from_u32_unchecked(i: u32) -> char { |
| transmute(i) |
| } |
| |
| /// Converts a digit in the given radix to a `char`. |
| /// |
| /// A 'radix' here is sometimes also called a 'base'. A radix of two |
| /// indicates a binary number, a radix of ten, decimal, and a radix of |
| /// sixteen, hexadecimal, to give some common values. Arbitrary |
| /// radicum are supported. |
| /// |
| /// `from_digit()` will return `None` if the input is not a digit in |
| /// the given radix. |
| /// |
| /// # Panics |
| /// |
| /// Panics if given a radix larger than 36. |
| /// |
| /// # Examples |
| /// |
| /// Basic usage: |
| /// |
| /// ``` |
| /// use std::char; |
| /// |
| /// let c = char::from_digit(4, 10); |
| /// |
| /// assert_eq!(Some('4'), c); |
| /// |
| /// // Decimal 11 is a single digit in base 16 |
| /// let c = char::from_digit(11, 16); |
| /// |
| /// assert_eq!(Some('b'), c); |
| /// ``` |
| /// |
| /// Returning `None` when the input is not a digit: |
| /// |
| /// ``` |
| /// use std::char; |
| /// |
| /// let c = char::from_digit(20, 10); |
| /// |
| /// assert_eq!(None, c); |
| /// ``` |
| /// |
| /// Passing a large radix, causing a panic: |
| /// |
| /// ``` |
| /// use std::thread; |
| /// use std::char; |
| /// |
| /// let result = thread::spawn(|| { |
| /// // this panics |
| /// let c = char::from_digit(1, 37); |
| /// }).join(); |
| /// |
| /// assert!(result.is_err()); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn from_digit(num: u32, radix: u32) -> Option<char> { |
| if radix > 36 { |
| panic!("from_digit: radix is too high (maximum 36)"); |
| } |
| if num < radix { |
| let num = num as u8; |
| if num < 10 { |
| Some((b'0' + num) as char) |
| } else { |
| Some((b'a' + num - 10) as char) |
| } |
| } else { |
| None |
| } |
| } |
| |
| // NB: the stabilization and documentation for this trait is in |
| // unicode/char.rs, not here |
| #[allow(missing_docs)] // docs in libunicode/u_char.rs |
| #[doc(hidden)] |
| #[unstable(feature = "core_char_ext", |
| reason = "the stable interface is `impl char` in later crate", |
| issue = "32110")] |
| pub trait CharExt { |
| #[stable(feature = "core", since = "1.6.0")] |
| fn is_digit(self, radix: u32) -> bool; |
| #[stable(feature = "core", since = "1.6.0")] |
| fn to_digit(self, radix: u32) -> Option<u32>; |
| #[stable(feature = "core", since = "1.6.0")] |
| fn escape_unicode(self) -> EscapeUnicode; |
| #[stable(feature = "core", since = "1.6.0")] |
| fn escape_default(self) -> EscapeDefault; |
| #[stable(feature = "core", since = "1.6.0")] |
| fn len_utf8(self) -> usize; |
| #[stable(feature = "core", since = "1.6.0")] |
| fn len_utf16(self) -> usize; |
| #[unstable(feature = "unicode", issue = "27784")] |
| fn encode_utf8(self) -> EncodeUtf8; |
| #[unstable(feature = "unicode", issue = "27784")] |
| fn encode_utf16(self) -> EncodeUtf16; |
| } |
| |
| #[stable(feature = "core", since = "1.6.0")] |
| impl CharExt for char { |
| #[inline] |
| fn is_digit(self, radix: u32) -> bool { |
| self.to_digit(radix).is_some() |
| } |
| |
| #[inline] |
| fn to_digit(self, radix: u32) -> Option<u32> { |
| if radix > 36 { |
| panic!("to_digit: radix is too high (maximum 36)"); |
| } |
| let val = match self { |
| '0' ... '9' => self as u32 - '0' as u32, |
| 'a' ... 'z' => self as u32 - 'a' as u32 + 10, |
| 'A' ... 'Z' => self as u32 - 'A' as u32 + 10, |
| _ => return None, |
| }; |
| if val < radix { Some(val) } |
| else { None } |
| } |
| |
| #[inline] |
| fn escape_unicode(self) -> EscapeUnicode { |
| let c = self as u32; |
| |
| // or-ing 1 ensures that for c==0 the code computes that one |
| // digit should be printed and (which is the same) avoids the |
| // (31 - 32) underflow |
| let msb = 31 - (c | 1).leading_zeros(); |
| |
| // the index of the most significant hex digit |
| let ms_hex_digit = msb / 4; |
| EscapeUnicode { |
| c: self, |
| state: EscapeUnicodeState::Backslash, |
| hex_digit_idx: ms_hex_digit as usize, |
| } |
| } |
| |
| #[inline] |
| fn escape_default(self) -> EscapeDefault { |
| let init_state = match self { |
| '\t' => EscapeDefaultState::Backslash('t'), |
| '\r' => EscapeDefaultState::Backslash('r'), |
| '\n' => EscapeDefaultState::Backslash('n'), |
| '\\' | '\'' | '"' => EscapeDefaultState::Backslash(self), |
| '\x20' ... '\x7e' => EscapeDefaultState::Char(self), |
| _ => EscapeDefaultState::Unicode(self.escape_unicode()) |
| }; |
| EscapeDefault { state: init_state } |
| } |
| |
| #[inline] |
| fn len_utf8(self) -> usize { |
| let code = self as u32; |
| if code < MAX_ONE_B { |
| 1 |
| } else if code < MAX_TWO_B { |
| 2 |
| } else if code < MAX_THREE_B { |
| 3 |
| } else { |
| 4 |
| } |
| } |
| |
| #[inline] |
| fn len_utf16(self) -> usize { |
| let ch = self as u32; |
| if (ch & 0xFFFF) == ch { 1 } else { 2 } |
| } |
| |
| #[inline] |
| fn encode_utf8(self) -> EncodeUtf8 { |
| let code = self as u32; |
| let mut buf = [0; 4]; |
| let pos = if code < MAX_ONE_B { |
| buf[3] = code as u8; |
| 3 |
| } else if code < MAX_TWO_B { |
| buf[2] = (code >> 6 & 0x1F) as u8 | TAG_TWO_B; |
| buf[3] = (code & 0x3F) as u8 | TAG_CONT; |
| 2 |
| } else if code < MAX_THREE_B { |
| buf[1] = (code >> 12 & 0x0F) as u8 | TAG_THREE_B; |
| buf[2] = (code >> 6 & 0x3F) as u8 | TAG_CONT; |
| buf[3] = (code & 0x3F) as u8 | TAG_CONT; |
| 1 |
| } else { |
| buf[0] = (code >> 18 & 0x07) as u8 | TAG_FOUR_B; |
| buf[1] = (code >> 12 & 0x3F) as u8 | TAG_CONT; |
| buf[2] = (code >> 6 & 0x3F) as u8 | TAG_CONT; |
| buf[3] = (code & 0x3F) as u8 | TAG_CONT; |
| 0 |
| }; |
| EncodeUtf8 { buf: buf, pos: pos } |
| } |
| |
| #[inline] |
| fn encode_utf16(self) -> EncodeUtf16 { |
| let mut buf = [0; 2]; |
| let mut code = self as u32; |
| let pos = if (code & 0xFFFF) == code { |
| // The BMP falls through (assuming non-surrogate, as it should) |
| buf[1] = code as u16; |
| 1 |
| } else { |
| // Supplementary planes break into surrogates. |
| code -= 0x1_0000; |
| buf[0] = 0xD800 | ((code >> 10) as u16); |
| buf[1] = 0xDC00 | ((code as u16) & 0x3FF); |
| 0 |
| }; |
| EncodeUtf16 { buf: buf, pos: pos } |
| } |
| } |
| |
| /// Returns an iterator that yields the hexadecimal Unicode escape of a |
| /// character, as `char`s. |
| /// |
| /// This `struct` is created by the [`escape_unicode()`] method on [`char`]. See |
| /// its documentation for more. |
| /// |
| /// [`escape_unicode()`]: ../../std/primitive.char.html#method.escape_unicode |
| /// [`char`]: ../../std/primitive.char.html |
| #[derive(Clone, Debug)] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub struct EscapeUnicode { |
| c: char, |
| state: EscapeUnicodeState, |
| |
| // The index of the next hex digit to be printed (0 if none), |
| // i.e. the number of remaining hex digits to be printed; |
| // increasing from the least significant digit: 0x543210 |
| hex_digit_idx: usize, |
| } |
| |
| // The enum values are ordered so that their representation is the |
| // same as the remaining length (besides the hexadecimal digits). This |
| // likely makes `len()` a single load from memory) and inline-worth. |
| #[derive(Clone, Debug)] |
| enum EscapeUnicodeState { |
| Done, |
| RightBrace, |
| Value, |
| LeftBrace, |
| Type, |
| Backslash, |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl Iterator for EscapeUnicode { |
| type Item = char; |
| |
| fn next(&mut self) -> Option<char> { |
| match self.state { |
| EscapeUnicodeState::Backslash => { |
| self.state = EscapeUnicodeState::Type; |
| Some('\\') |
| } |
| EscapeUnicodeState::Type => { |
| self.state = EscapeUnicodeState::LeftBrace; |
| Some('u') |
| } |
| EscapeUnicodeState::LeftBrace => { |
| self.state = EscapeUnicodeState::Value; |
| Some('{') |
| } |
| EscapeUnicodeState::Value => { |
| let hex_digit = ((self.c as u32) >> (self.hex_digit_idx * 4)) & 0xf; |
| let c = from_digit(hex_digit, 16).unwrap(); |
| if self.hex_digit_idx == 0 { |
| self.state = EscapeUnicodeState::RightBrace; |
| } else { |
| self.hex_digit_idx -= 1; |
| } |
| Some(c) |
| } |
| EscapeUnicodeState::RightBrace => { |
| self.state = EscapeUnicodeState::Done; |
| Some('}') |
| } |
| EscapeUnicodeState::Done => None, |
| } |
| } |
| |
| #[inline] |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| let n = self.len(); |
| (n, Some(n)) |
| } |
| |
| #[inline] |
| fn count(self) -> usize { |
| self.len() |
| } |
| |
| fn last(self) -> Option<char> { |
| match self.state { |
| EscapeUnicodeState::Done => None, |
| |
| EscapeUnicodeState::RightBrace | |
| EscapeUnicodeState::Value | |
| EscapeUnicodeState::LeftBrace | |
| EscapeUnicodeState::Type | |
| EscapeUnicodeState::Backslash => Some('}'), |
| } |
| } |
| } |
| |
| #[stable(feature = "exact_size_escape", since = "1.11.0")] |
| impl ExactSizeIterator for EscapeUnicode { |
| #[inline] |
| fn len(&self) -> usize { |
| // The match is a single memory access with no branching |
| self.hex_digit_idx + match self.state { |
| EscapeUnicodeState::Done => 0, |
| EscapeUnicodeState::RightBrace => 1, |
| EscapeUnicodeState::Value => 2, |
| EscapeUnicodeState::LeftBrace => 3, |
| EscapeUnicodeState::Type => 4, |
| EscapeUnicodeState::Backslash => 5, |
| } |
| } |
| } |
| |
| /// An iterator that yields the literal escape code of a `char`. |
| /// |
| /// This `struct` is created by the [`escape_default()`] method on [`char`]. See |
| /// its documentation for more. |
| /// |
| /// [`escape_default()`]: ../../std/primitive.char.html#method.escape_default |
| /// [`char`]: ../../std/primitive.char.html |
| #[derive(Clone, Debug)] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub struct EscapeDefault { |
| state: EscapeDefaultState |
| } |
| |
| #[derive(Clone, Debug)] |
| enum EscapeDefaultState { |
| Done, |
| Char(char), |
| Backslash(char), |
| Unicode(EscapeUnicode), |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl Iterator for EscapeDefault { |
| type Item = char; |
| |
| fn next(&mut self) -> Option<char> { |
| match self.state { |
| EscapeDefaultState::Backslash(c) => { |
| self.state = EscapeDefaultState::Char(c); |
| Some('\\') |
| } |
| EscapeDefaultState::Char(c) => { |
| self.state = EscapeDefaultState::Done; |
| Some(c) |
| } |
| EscapeDefaultState::Done => None, |
| EscapeDefaultState::Unicode(ref mut iter) => iter.next(), |
| } |
| } |
| |
| #[inline] |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| let n = self.len(); |
| (n, Some(n)) |
| } |
| |
| #[inline] |
| fn count(self) -> usize { |
| self.len() |
| } |
| |
| fn nth(&mut self, n: usize) -> Option<char> { |
| match self.state { |
| EscapeDefaultState::Backslash(c) if n == 0 => { |
| self.state = EscapeDefaultState::Char(c); |
| Some('\\') |
| }, |
| EscapeDefaultState::Backslash(c) if n == 1 => { |
| self.state = EscapeDefaultState::Done; |
| Some(c) |
| }, |
| EscapeDefaultState::Backslash(_) => { |
| self.state = EscapeDefaultState::Done; |
| None |
| }, |
| EscapeDefaultState::Char(c) => { |
| self.state = EscapeDefaultState::Done; |
| |
| if n == 0 { |
| Some(c) |
| } else { |
| None |
| } |
| }, |
| EscapeDefaultState::Done => return None, |
| EscapeDefaultState::Unicode(ref mut i) => return i.nth(n), |
| } |
| } |
| |
| fn last(self) -> Option<char> { |
| match self.state { |
| EscapeDefaultState::Unicode(iter) => iter.last(), |
| EscapeDefaultState::Done => None, |
| EscapeDefaultState::Backslash(c) | EscapeDefaultState::Char(c) => Some(c), |
| } |
| } |
| } |
| |
| #[stable(feature = "exact_size_escape", since = "1.11.0")] |
| impl ExactSizeIterator for EscapeDefault { |
| fn len(&self) -> usize { |
| match self.state { |
| EscapeDefaultState::Done => 0, |
| EscapeDefaultState::Char(_) => 1, |
| EscapeDefaultState::Backslash(_) => 2, |
| EscapeDefaultState::Unicode(ref iter) => iter.len(), |
| } |
| } |
| } |
| |
| /// An iterator over `u8` entries represending the UTF-8 encoding of a `char` |
| /// value. |
| /// |
| /// Constructed via the `.encode_utf8()` method on `char`. |
| #[unstable(feature = "unicode", issue = "27784")] |
| #[derive(Debug)] |
| pub struct EncodeUtf8 { |
| buf: [u8; 4], |
| pos: usize, |
| } |
| |
| impl EncodeUtf8 { |
| /// Returns the remaining bytes of this iterator as a slice. |
| #[unstable(feature = "unicode", issue = "27784")] |
| pub fn as_slice(&self) -> &[u8] { |
| &self.buf[self.pos..] |
| } |
| } |
| |
| #[unstable(feature = "unicode", issue = "27784")] |
| impl Iterator for EncodeUtf8 { |
| type Item = u8; |
| |
| fn next(&mut self) -> Option<u8> { |
| if self.pos == self.buf.len() { |
| None |
| } else { |
| let ret = Some(self.buf[self.pos]); |
| self.pos += 1; |
| ret |
| } |
| } |
| |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| self.as_slice().iter().size_hint() |
| } |
| } |
| |
| /// An iterator over `u16` entries represending the UTF-16 encoding of a `char` |
| /// value. |
| /// |
| /// Constructed via the `.encode_utf16()` method on `char`. |
| #[unstable(feature = "unicode", issue = "27784")] |
| #[derive(Debug)] |
| pub struct EncodeUtf16 { |
| buf: [u16; 2], |
| pos: usize, |
| } |
| |
| impl EncodeUtf16 { |
| /// Returns the remaining bytes of this iterator as a slice. |
| #[unstable(feature = "unicode", issue = "27784")] |
| pub fn as_slice(&self) -> &[u16] { |
| &self.buf[self.pos..] |
| } |
| } |
| |
| |
| #[unstable(feature = "unicode", issue = "27784")] |
| impl Iterator for EncodeUtf16 { |
| type Item = u16; |
| |
| fn next(&mut self) -> Option<u16> { |
| if self.pos == self.buf.len() { |
| None |
| } else { |
| let ret = Some(self.buf[self.pos]); |
| self.pos += 1; |
| ret |
| } |
| } |
| |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| self.as_slice().iter().size_hint() |
| } |
| } |
| |
| |
| /// An iterator over an iterator of bytes of the characters the bytes represent |
| /// as UTF-8 |
| #[unstable(feature = "decode_utf8", issue = "33906")] |
| #[derive(Clone, Debug)] |
| pub struct DecodeUtf8<I: Iterator<Item = u8>>(::iter::Peekable<I>); |
| |
| /// Decodes an `Iterator` of bytes as UTF-8. |
| #[unstable(feature = "decode_utf8", issue = "33906")] |
| #[inline] |
| pub fn decode_utf8<I: IntoIterator<Item = u8>>(i: I) -> DecodeUtf8<I::IntoIter> { |
| DecodeUtf8(i.into_iter().peekable()) |
| } |
| |
| /// `<DecodeUtf8 as Iterator>::next` returns this for an invalid input sequence. |
| #[unstable(feature = "decode_utf8", issue = "33906")] |
| #[derive(PartialEq, Debug)] |
| pub struct InvalidSequence(()); |
| |
| #[unstable(feature = "decode_utf8", issue = "33906")] |
| impl<I: Iterator<Item = u8>> Iterator for DecodeUtf8<I> { |
| type Item = Result<char, InvalidSequence>; |
| #[inline] |
| fn next(&mut self) -> Option<Result<char, InvalidSequence>> { |
| self.0.next().map(|b| { |
| if b & 0x80 == 0 { Ok(b as char) } else { |
| let l = (!b).leading_zeros() as usize; // number of bytes in UTF-8 representation |
| if l < 2 || l > 6 { return Err(InvalidSequence(())) }; |
| let mut x = (b as u32) & (0x7F >> l); |
| for _ in 0..l-1 { |
| match self.0.peek() { |
| Some(&b) if b & 0xC0 == 0x80 => { |
| self.0.next(); |
| x = (x << 6) | (b as u32) & 0x3F; |
| }, |
| _ => return Err(InvalidSequence(())), |
| } |
| } |
| match from_u32(x) { |
| Some(x) if l == x.len_utf8() => Ok(x), |
| _ => Err(InvalidSequence(())), |
| } |
| } |
| }) |
| } |
| } |