/*
*******************************************************************************
*
* Copyright (C) 1999-2010, International Business Machines
* Corporation and others. All Rights Reserved.
*
*******************************************************************************
* file name: utf.h
* encoding: US-ASCII
* tab size: 8 (not used)
* indentation:4
*
* created on: 1999sep09
* created by: Markus W. Scherer
*/
/**
* \file
* \brief C API: Code point macros
*
* This file defines macros for checking whether a code point is
* a surrogate or a non-character etc.
*
* The UChar and UChar32 data types for Unicode code units and code points
* are defined in umachines.h because they can be machine-dependent.
*
* utf.h is included by utypes.h and itself includes utf8.h and utf16.h after some
* common definitions. Those files define macros for efficiently getting code points
* in and out of UTF-8/16 strings.
* utf16.h macros have "U16_" prefixes.
* utf8.h defines similar macros with "U8_" prefixes for UTF-8 string handling.
*
* ICU processes 16-bit Unicode strings.
* Most of the time, such strings are well-formed UTF-16.
* Single, unpaired surrogates must be handled as well, and are treated in ICU
* like regular code points where possible.
* (Pairs of surrogate code points are indistinguishable from supplementary
* code points encoded as pairs of supplementary code units.)
*
* In fact, almost all Unicode code points in normal text (>99%)
* are on the BMP (<=U+ffff) and even <=U+d7ff.
* ICU functions handle supplementary code points (U+10000..U+10ffff)
* but are optimized for the much more frequently occurring BMP code points.
*
* utf.h defines UChar to be an unsigned 16-bit integer. If this matches wchar_t, then
* UChar is defined to be exactly wchar_t, otherwise uint16_t.
*
* UChar32 is defined to be a signed 32-bit integer (int32_t), large enough for a 21-bit
* Unicode code point (Unicode scalar value, 0..0x10ffff).
* Before ICU 2.4, the definition of UChar32 was similarly platform-dependent as
* the definition of UChar. For details see the documentation for UChar32 itself.
*
* utf.h also defines a small number of C macros for single Unicode code points.
* These are simple checks for surrogates and non-characters.
* For actual Unicode character properties see uchar.h.
*
* By default, string operations must be done with error checking in case
* a string is not well-formed UTF-16.
* The macros will detect if a surrogate code unit is unpaired
* (lead unit without trail unit or vice versa) and just return the unit itself
* as the code point.
* (It is an accidental property of Unicode and UTF-16 that all
* malformed sequences can be expressed unambiguously with a distinct subrange
* of Unicode code points.)
*
* The regular "safe" macros require that the initial, passed-in string index
* is within bounds. They only check the index when they read more than one
* code unit. This is usually done with code similar to the following loop:
* <pre>while(i<length) {
* U16_NEXT(s, i, length, c);
* // use c
* }</pre>
*
* When it is safe to assume that text is well-formed UTF-16
* (does not contain single, unpaired surrogates), then one can use
* U16_..._UNSAFE macros.
* These do not check for proper code unit sequences or truncated text and may
* yield wrong results or even cause a crash if they are used with "malformed"
* text.
* In practice, U16_..._UNSAFE macros will produce slightly less code but
* should not be faster because the processing is only different when a
* surrogate code unit is detected, which will be rare.
*
* Similarly for UTF-8, there are "safe" macros without a suffix,
* and U8_..._UNSAFE versions.
* The performance differences are much larger here because UTF-8 provides so
* many opportunities for malformed sequences.
* The unsafe UTF-8 macros are entirely implemented inside the macro definitions
* and are fast, while the safe UTF-8 macros call functions for all but the
* trivial (ASCII) cases.
* (ICU 3.6 optimizes U8_NEXT() and U8_APPEND() to handle most other common
* characters inline as well.)
*
* Unlike with UTF-16, malformed sequences cannot be expressed with distinct
* code point values (0..U+10ffff). They are indicated with negative values instead.
*
* For more information see the ICU User Guide Strings chapter
* (http://icu-project.org/userguide/strings.html).
*
* <em>Usage:</em>
* ICU coding guidelines for if() statements should be followed when using these macros.
* Compound statements (curly braces {}) must be used for if-else-while...
* bodies and all macro statements should be terminated with semicolon.
*
* @stable ICU 2.4
*/
#ifndef __UTF_H__
#define __UTF_H__
#include "unicode/utypes.h"
/* include the utfXX.h after the following definitions */
/* single-code point definitions -------------------------------------------- */
/**
* This value is intended for sentinel values for APIs that
* (take or) return single code points (UChar32).
* It is outside of the Unicode code point range 0..0x10ffff.
*
* For example, a "done" or "error" value in a new API
* could be indicated with U_SENTINEL.
*
* ICU APIs designed before ICU 2.4 usually define service-specific "done"
* values, mostly 0xffff.
* Those may need to be distinguished from
* actual U+ffff text contents by calling functions like
* CharacterIterator::hasNext() or UnicodeString::length().
*
* @return -1
* @see UChar32
* @stable ICU 2.4
*/
#define U_SENTINEL (-1)
/**
* Is this code point a Unicode noncharacter?
* @param c 32-bit code point
* @return TRUE or FALSE
* @stable ICU 2.4
*/
#define U_IS_UNICODE_NONCHAR(c) \
((c)>=0xfdd0 && \
((uint32_t)(c)<=0xfdef || ((c)&0xfffe)==0xfffe) && \
(uint32_t)(c)<=0x10ffff)
/**
* Is c a Unicode code point value (0..U+10ffff)
* that can be assigned a character?
*
* Code points that are not characters include:
* - single surrogate code points (U+d800..U+dfff, 2048 code points)
* - the last two code points on each plane (U+__fffe and U+__ffff, 34 code points)
* - U+fdd0..U+fdef (new with Unicode 3.1, 32 code points)
* - the highest Unicode code point value is U+10ffff
*
* This means that all code points below U+d800 are character code points,
* and that boundary is tested first for performance.
*
* @param c 32-bit code point
* @return TRUE or FALSE
* @stable ICU 2.4
*/
#define U_IS_UNICODE_CHAR(c) \
((uint32_t)(c)<0xd800 || \
((uint32_t)(c)>0xdfff && \
(uint32_t)(c)<=0x10ffff && \
!U_IS_UNICODE_NONCHAR(c)))
/**
* Is this code point a BMP code point (U+0000..U+ffff)?
* @param c 32-bit code point
* @return TRUE or FALSE
* @stable ICU 2.8
*/
#define U_IS_BMP(c) ((uint32_t)(c)<=0xffff)
/**
* Is this code point a supplementary code point (U+10000..U+10ffff)?
* @param c 32-bit code point
* @return TRUE or FALSE
* @stable ICU 2.8
*/
#define U_IS_SUPPLEMENTARY(c) ((uint32_t)((c)-0x10000)<=0xfffff)
/**
* Is this code point a lead surrogate (U+d800..U+dbff)?
* @param c 32-bit code point
* @return TRUE or FALSE
* @stable ICU 2.4
*/
#define U_IS_LEAD(c) (((c)&0xfffffc00)==0xd800)
/**
* Is this code point a trail surrogate (U+dc00..U+dfff)?
* @param c 32-bit code point
* @return TRUE or FALSE
* @stable ICU 2.4
*/
#define U_IS_TRAIL(c) (((c)&0xfffffc00)==0xdc00)
/**
* Is this code point a surrogate (U+d800..U+dfff)?
* @param c 32-bit code point
* @return TRUE or FALSE
* @stable ICU 2.4
*/
#define U_IS_SURROGATE(c) (((c)&0xfffff800)==0xd800)
/**
* Assuming c is a surrogate code point (U_IS_SURROGATE(c)),
* is it a lead surrogate?
* @param c 32-bit code point
* @return TRUE or FALSE
* @stable ICU 2.4
*/
#define U_IS_SURROGATE_LEAD(c) (((c)&0x400)==0)
/**
* Assuming c is a surrogate code point (U_IS_SURROGATE(c)),
* is it a trail surrogate?
* @param c 32-bit code point
* @return TRUE or FALSE
* @stable ICU 4.2
*/
#define U_IS_SURROGATE_TRAIL(c) (((c)&0x400)!=0)
/* include the utfXX.h ------------------------------------------------------ */
#include "unicode/utf8.h"
#include "unicode/utf16.h"
/* utf_old.h contains deprecated, pre-ICU 2.4 definitions */
#include "unicode/utf_old.h"
#endif