318 lines
13 KiB
Rust
318 lines
13 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Unicode-intensive `char` methods along with the `core` methods.
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//!
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//! These methods implement functionality for `char` that requires knowledge of
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//! Unicode definitions, including normalization, categorization, and display information.
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use core::char;
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use core::char::CharExt as C;
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use core::option::Option;
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use tables::{derived_property, property, general_category, conversions, charwidth};
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/// Functionality for manipulating `char`.
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#[stable(feature = "rust1", since = "1.0.0")]
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pub trait CharExt {
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/// Checks if a `char` parses as a numeric digit in the given radix.
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///
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/// Compared to `is_numeric()`, this function only recognizes the characters
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/// `0-9`, `a-z` and `A-Z`.
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///
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/// # Return value
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///
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/// Returns `true` if `c` is a valid digit under `radix`, and `false`
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/// otherwise.
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///
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/// # Panics
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///
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/// Panics if given a radix > 36.
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#[unstable(feature = "unicode",
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reason = "pending integer conventions")]
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fn is_digit(self, radix: u32) -> bool;
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/// Converts a character to the corresponding digit.
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///
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/// # Return value
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///
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/// If `c` is between '0' and '9', the corresponding value between 0 and
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/// 9. If `c` is 'a' or 'A', 10. If `c` is 'b' or 'B', 11, etc. Returns
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/// none if the character does not refer to a digit in the given radix.
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///
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/// # Panics
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///
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/// Panics if given a radix outside the range [0..36].
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#[unstable(feature = "unicode",
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reason = "pending integer conventions")]
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fn to_digit(self, radix: u32) -> Option<u32>;
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/// Returns an iterator that yields the hexadecimal Unicode escape
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/// of a character, as `char`s.
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///
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/// All characters are escaped with Rust syntax of the form `\\u{NNNN}`
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/// where `NNNN` is the shortest hexadecimal representation of the code
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/// point.
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#[stable(feature = "rust1", since = "1.0.0")]
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fn escape_unicode(self) -> char::EscapeUnicode;
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/// Returns an iterator that yields the 'default' ASCII and
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/// C++11-like literal escape of a character, as `char`s.
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///
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/// The default is chosen with a bias toward producing literals that are
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/// legal in a variety of languages, including C++11 and similar C-family
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/// languages. The exact rules are:
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///
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/// * Tab, CR and LF are escaped as '\t', '\r' and '\n' respectively.
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/// * Single-quote, double-quote and backslash chars are backslash-
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/// escaped.
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/// * Any other chars in the range [0x20,0x7e] are not escaped.
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/// * Any other chars are given hex Unicode escapes; see `escape_unicode`.
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#[stable(feature = "rust1", since = "1.0.0")]
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fn escape_default(self) -> char::EscapeDefault;
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/// Returns the amount of bytes this character would need if encoded in
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/// UTF-8.
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#[stable(feature = "rust1", since = "1.0.0")]
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fn len_utf8(self) -> usize;
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/// Returns the amount of bytes this character would need if encoded in
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/// UTF-16.
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#[stable(feature = "rust1", since = "1.0.0")]
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fn len_utf16(self) -> usize;
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/// Encodes this character as UTF-8 into the provided byte buffer,
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/// and then returns the number of bytes written.
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///
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/// If the buffer is not large enough, nothing will be written into it
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/// and a `None` will be returned.
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#[unstable(feature = "unicode",
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reason = "pending decision about Iterator/Writer/Reader")]
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fn encode_utf8(self, dst: &mut [u8]) -> Option<usize>;
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/// Encodes this character as UTF-16 into the provided `u16` buffer,
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/// and then returns the number of `u16`s written.
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///
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/// If the buffer is not large enough, nothing will be written into it
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/// and a `None` will be returned.
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#[unstable(feature = "unicode",
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reason = "pending decision about Iterator/Writer/Reader")]
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fn encode_utf16(self, dst: &mut [u16]) -> Option<usize>;
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/// Returns whether the specified character is considered a Unicode
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/// alphabetic code point.
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#[stable(feature = "rust1", since = "1.0.0")]
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fn is_alphabetic(self) -> bool;
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/// Returns whether the specified character satisfies the 'XID_Start'
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/// Unicode property.
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///
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/// 'XID_Start' is a Unicode Derived Property specified in
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/// [UAX #31](http://unicode.org/reports/tr31/#NFKC_Modifications),
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/// mostly similar to ID_Start but modified for closure under NFKx.
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#[unstable(feature = "unicode",
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reason = "mainly needed for compiler internals")]
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fn is_xid_start(self) -> bool;
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/// Returns whether the specified `char` satisfies the 'XID_Continue'
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/// Unicode property.
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///
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/// 'XID_Continue' is a Unicode Derived Property specified in
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/// [UAX #31](http://unicode.org/reports/tr31/#NFKC_Modifications),
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/// mostly similar to 'ID_Continue' but modified for closure under NFKx.
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#[unstable(feature = "unicode",
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reason = "mainly needed for compiler internals")]
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fn is_xid_continue(self) -> bool;
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/// Indicates whether a character is in lowercase.
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///
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/// This is defined according to the terms of the Unicode Derived Core
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/// Property `Lowercase`.
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#[stable(feature = "rust1", since = "1.0.0")]
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fn is_lowercase(self) -> bool;
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/// Indicates whether a character is in uppercase.
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///
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/// This is defined according to the terms of the Unicode Derived Core
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/// Property `Uppercase`.
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#[stable(feature = "rust1", since = "1.0.0")]
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fn is_uppercase(self) -> bool;
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/// Indicates whether a character is whitespace.
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///
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/// Whitespace is defined in terms of the Unicode Property `White_Space`.
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#[stable(feature = "rust1", since = "1.0.0")]
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fn is_whitespace(self) -> bool;
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/// Indicates whether a character is alphanumeric.
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///
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/// Alphanumericness is defined in terms of the Unicode General Categories
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/// 'Nd', 'Nl', 'No' and the Derived Core Property 'Alphabetic'.
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#[stable(feature = "rust1", since = "1.0.0")]
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fn is_alphanumeric(self) -> bool;
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/// Indicates whether a character is a control code point.
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///
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/// Control code points are defined in terms of the Unicode General
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/// Category `Cc`.
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#[stable(feature = "rust1", since = "1.0.0")]
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fn is_control(self) -> bool;
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/// Indicates whether the character is numeric (Nd, Nl, or No).
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#[stable(feature = "rust1", since = "1.0.0")]
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fn is_numeric(self) -> bool;
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/// Converts a character to its lowercase equivalent.
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///
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/// The case-folding performed is the common or simple mapping. See
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/// `to_uppercase()` for references and more information.
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///
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/// # Return value
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///
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/// Returns the lowercase equivalent of the character, or the character
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/// itself if no conversion is possible.
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#[unstable(feature = "unicode",
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reason = "pending case transformation decisions")]
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fn to_lowercase(self) -> char;
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/// Converts a character to its uppercase equivalent.
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///
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/// The case-folding performed is the common or simple mapping: it maps
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/// one Unicode codepoint (one character in Rust) to its uppercase
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/// equivalent according to the Unicode database [1]. The additional
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/// [`SpecialCasing.txt`] is not considered here, as it expands to multiple
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/// codepoints in some cases.
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///
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/// A full reference can be found here [2].
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///
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/// # Return value
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///
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/// Returns the uppercase equivalent of the character, or the character
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/// itself if no conversion was made.
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///
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/// [1]: ftp://ftp.unicode.org/Public/UNIDATA/UnicodeData.txt
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///
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/// [`SpecialCasing`.txt`]: ftp://ftp.unicode.org/Public/UNIDATA/SpecialCasing.txt
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///
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/// [2]: http://www.unicode.org/versions/Unicode4.0.0/ch03.pdf#G33992
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#[unstable(feature = "unicode",
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reason = "pending case transformation decisions")]
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fn to_uppercase(self) -> char;
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/// Returns this character's displayed width in columns, or `None` if it is a
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/// control character other than `'\x00'`.
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///
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/// `is_cjk` determines behavior for characters in the Ambiguous category:
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/// if `is_cjk` is `true`, these are 2 columns wide; otherwise, they are 1.
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/// In CJK contexts, `is_cjk` should be `true`, else it should be `false`.
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/// [Unicode Standard Annex #11](http://www.unicode.org/reports/tr11/)
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/// recommends that these characters be treated as 1 column (i.e.,
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/// `is_cjk` = `false`) if the context cannot be reliably determined.
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#[unstable(feature = "unicode",
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reason = "needs expert opinion. is_cjk flag stands out as ugly")]
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fn width(self, is_cjk: bool) -> Option<usize>;
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl CharExt for char {
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#[unstable(feature = "unicode",
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reason = "pending integer conventions")]
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fn is_digit(self, radix: u32) -> bool { C::is_digit(self, radix) }
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#[unstable(feature = "unicode",
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reason = "pending integer conventions")]
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fn to_digit(self, radix: u32) -> Option<u32> { C::to_digit(self, radix) }
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#[stable(feature = "rust1", since = "1.0.0")]
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fn escape_unicode(self) -> char::EscapeUnicode { C::escape_unicode(self) }
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#[stable(feature = "rust1", since = "1.0.0")]
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fn escape_default(self) -> char::EscapeDefault { C::escape_default(self) }
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#[stable(feature = "rust1", since = "1.0.0")]
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fn len_utf8(self) -> usize { C::len_utf8(self) }
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#[stable(feature = "rust1", since = "1.0.0")]
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fn len_utf16(self) -> usize { C::len_utf16(self) }
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#[unstable(feature = "unicode",
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reason = "pending decision about Iterator/Writer/Reader")]
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fn encode_utf8(self, dst: &mut [u8]) -> Option<usize> { C::encode_utf8(self, dst) }
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#[unstable(feature = "unicode",
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reason = "pending decision about Iterator/Writer/Reader")]
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fn encode_utf16(self, dst: &mut [u16]) -> Option<usize> { C::encode_utf16(self, dst) }
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#[stable(feature = "rust1", since = "1.0.0")]
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fn is_alphabetic(self) -> bool {
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match self {
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'a' ... 'z' | 'A' ... 'Z' => true,
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c if c > '\x7f' => derived_property::Alphabetic(c),
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_ => false
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}
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}
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#[unstable(feature = "unicode",
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reason = "mainly needed for compiler internals")]
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fn is_xid_start(self) -> bool { derived_property::XID_Start(self) }
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#[unstable(feature = "unicode",
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reason = "mainly needed for compiler internals")]
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fn is_xid_continue(self) -> bool { derived_property::XID_Continue(self) }
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#[stable(feature = "rust1", since = "1.0.0")]
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fn is_lowercase(self) -> bool {
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match self {
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'a' ... 'z' => true,
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c if c > '\x7f' => derived_property::Lowercase(c),
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_ => false
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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fn is_uppercase(self) -> bool {
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match self {
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'A' ... 'Z' => true,
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c if c > '\x7f' => derived_property::Uppercase(c),
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_ => false
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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fn is_whitespace(self) -> bool {
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match self {
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' ' | '\x09' ... '\x0d' => true,
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c if c > '\x7f' => property::White_Space(c),
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_ => false
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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fn is_alphanumeric(self) -> bool {
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self.is_alphabetic() || self.is_numeric()
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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fn is_control(self) -> bool { general_category::Cc(self) }
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#[stable(feature = "rust1", since = "1.0.0")]
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fn is_numeric(self) -> bool {
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match self {
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'0' ... '9' => true,
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c if c > '\x7f' => general_category::N(c),
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_ => false
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}
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}
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#[unstable(feature = "unicode",
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reason = "pending case transformation decisions")]
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fn to_lowercase(self) -> char { conversions::to_lower(self) }
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#[unstable(feature = "unicode",
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reason = "pending case transformation decisions")]
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fn to_uppercase(self) -> char { conversions::to_upper(self) }
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#[unstable(feature = "unicode",
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reason = "needs expert opinion. is_cjk flag stands out as ugly")]
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fn width(self, is_cjk: bool) -> Option<usize> { charwidth::width(self, is_cjk) }
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}
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