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PCRE - Perl-compatible regular expressions
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.SH "PCRE 16-BIT API BASIC FUNCTIONS"
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.B pcre16 *pcre16_compile(PCRE_SPTR16 \fIpattern\fP, int \fIoptions\fP,
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.B const char **\fIerrptr\fP, int *\fIerroffset\fP,
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.B const unsigned char *\fItableptr\fP);
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.B pcre16 *pcre16_compile2(PCRE_SPTR16 \fIpattern\fP, int \fIoptions\fP,
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.B int *\fIerrorcodeptr\fP,
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.B const char **\fIerrptr\fP, int *\fIerroffset\fP,
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.B const unsigned char *\fItableptr\fP);
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.B pcre16_extra *pcre16_study(const pcre16 *\fIcode\fP, int \fIoptions\fP,
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.B const char **\fIerrptr\fP);
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.B void pcre16_free_study(pcre16_extra *\fIextra\fP);
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.B int pcre16_exec(const pcre16 *\fIcode\fP, "const pcre16_extra *\fIextra\fP,"
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.B "PCRE_SPTR16 \fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
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.B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
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.B int pcre16_dfa_exec(const pcre16 *\fIcode\fP, "const pcre16_extra *\fIextra\fP,"
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.B "PCRE_SPTR16 \fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
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.B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
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.B int *\fIworkspace\fP, int \fIwscount\fP);
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.SH "PCRE 16-BIT API STRING EXTRACTION FUNCTIONS"
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.B int pcre16_copy_named_substring(const pcre16 *\fIcode\fP,
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.B PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,
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.B int \fIstringcount\fP, PCRE_SPTR16 \fIstringname\fP,
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.B PCRE_UCHAR16 *\fIbuffer\fP, int \fIbuffersize\fP);
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.B int pcre16_copy_substring(PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,
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.B int \fIstringcount\fP, int \fIstringnumber\fP, PCRE_UCHAR16 *\fIbuffer\fP,
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.B int \fIbuffersize\fP);
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.B int pcre16_get_named_substring(const pcre16 *\fIcode\fP,
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.B PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,
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.B int \fIstringcount\fP, PCRE_SPTR16 \fIstringname\fP,
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.B PCRE_SPTR16 *\fIstringptr\fP);
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.B int pcre16_get_stringnumber(const pcre16 *\fIcode\fP,
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.B PCRE_SPTR16 \fIname\fP);
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.B int pcre16_get_stringtable_entries(const pcre16 *\fIcode\fP,
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.B PCRE_SPTR16 \fIname\fP, PCRE_UCHAR16 **\fIfirst\fP, PCRE_UCHAR16 **\fIlast\fP);
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.B int pcre16_get_substring(PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,
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.B int \fIstringcount\fP, int \fIstringnumber\fP,
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.B PCRE_SPTR16 *\fIstringptr\fP);
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.B int pcre16_get_substring_list(PCRE_SPTR16 \fIsubject\fP,
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.B int *\fIovector\fP, int \fIstringcount\fP, "PCRE_SPTR16 **\fIlistptr\fP);"
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.B void pcre16_free_substring(PCRE_SPTR16 \fIstringptr\fP);
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.B void pcre16_free_substring_list(PCRE_SPTR16 *\fIstringptr\fP);
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.SH "PCRE 16-BIT API AUXILIARY FUNCTIONS"
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.B pcre16_jit_stack *pcre16_jit_stack_alloc(int \fIstartsize\fP, int \fImaxsize\fP);
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.B void pcre16_jit_stack_free(pcre16_jit_stack *\fIstack\fP);
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.B void pcre16_assign_jit_stack(pcre16_extra *\fIextra\fP,
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.B pcre16_jit_callback \fIcallback\fP, void *\fIdata\fP);
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.B const unsigned char *pcre16_maketables(void);
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.B int pcre16_fullinfo(const pcre16 *\fIcode\fP, "const pcre16_extra *\fIextra\fP,"
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.B int \fIwhat\fP, void *\fIwhere\fP);
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.B int pcre16_refcount(pcre16 *\fIcode\fP, int \fIadjust\fP);
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.B int pcre16_config(int \fIwhat\fP, void *\fIwhere\fP);
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.B const char *pcre16_version(void);
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.B int pcre16_pattern_to_host_byte_order(pcre16 *\fIcode\fP,
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.B pcre16_extra *\fIextra\fP, const unsigned char *\fItables\fP);
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.SH "PCRE 16-BIT API INDIRECTED FUNCTIONS"
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.B void *(*pcre16_malloc)(size_t);
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.B void (*pcre16_free)(void *);
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.B void *(*pcre16_stack_malloc)(size_t);
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.B void (*pcre16_stack_free)(void *);
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.B int (*pcre16_callout)(pcre16_callout_block *);
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.SH "PCRE 16-BIT API 16-BIT-ONLY FUNCTION"
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.B int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *\fIoutput\fP,
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.B PCRE_SPTR16 \fIinput\fP, int \fIlength\fP, int *\fIbyte_order\fP,
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.B int \fIkeep_boms\fP);
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.SH "THE PCRE 16-BIT LIBRARY"
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Starting with release 8.30, it is possible to compile a PCRE library that
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supports 16-bit character strings, including UTF-16 strings, as well as or
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instead of the original 8-bit library. The majority of the work to make this
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possible was done by Zoltan Herczeg. The two libraries contain identical sets
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of functions, used in exactly the same way. Only the names of the functions and
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the data types of their arguments and results are different. To avoid
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over-complication and reduce the documentation maintenance load, most of the
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PCRE documentation describes the 8-bit library, with only occasional references
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to the 16-bit library. This page describes what is different when you use the
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WARNING: A single application can be linked with both libraries, but you must
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take care when processing any particular pattern to use functions from just one
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library. For example, if you want to study a pattern that was compiled with
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\fBpcre16_compile()\fP, you must do so with \fBpcre16_study()\fP, not
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\fBpcre_study()\fP, and you must free the study data with
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\fBpcre16_free_study()\fP.
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.SH "THE HEADER FILE"
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There is only one header file, \fBpcre.h\fP. It contains prototypes for all the
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functions in both libraries, as well as definitions of flags, structures, error
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.SH "THE LIBRARY NAME"
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In Unix-like systems, the 16-bit library is called \fBlibpcre16\fP, and can
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normally be accesss by adding \fB-lpcre16\fP to the command for linking an
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application that uses PCRE.
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In the 8-bit library, strings are passed to PCRE library functions as vectors
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of bytes with the C type "char *". In the 16-bit library, strings are passed as
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vectors of unsigned 16-bit quantities. The macro PCRE_UCHAR16 specifies an
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appropriate data type, and PCRE_SPTR16 is defined as "const PCRE_UCHAR16 *". In
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very many environments, "short int" is a 16-bit data type. When PCRE is built,
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it defines PCRE_UCHAR16 as "short int", but checks that it really is a 16-bit
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data type. If it is not, the build fails with an error message telling the
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maintainer to modify the definition appropriately.
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.SH "STRUCTURE TYPES"
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The types of the opaque structures that are used for compiled 16-bit patterns
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and JIT stacks are \fBpcre16\fP and \fBpcre16_jit_stack\fP respectively. The
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type of the user-accessible structure that is returned by \fBpcre16_study()\fP
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is \fBpcre16_extra\fP, and the type of the structure that is used for passing
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data to a callout function is \fBpcre16_callout_block\fP. These structures
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contain the same fields, with the same names, as their 8-bit counterparts. The
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only difference is that pointers to character strings are 16-bit instead of
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.SH "16-BIT FUNCTIONS"
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For every function in the 8-bit library there is a corresponding function in
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the 16-bit library with a name that starts with \fBpcre16_\fP instead of
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\fBpcre_\fP. The prototypes are listed above. In addition, there is one extra
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function, \fBpcre16_utf16_to_host_byte_order()\fP. This is a utility function
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that converts a UTF-16 character string to host byte order if necessary. The
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other 16-bit functions expect the strings they are passed to be in host byte
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The \fIinput\fP and \fIoutput\fP arguments of
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\fBpcre16_utf16_to_host_byte_order()\fP may point to the same address, that is,
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conversion in place is supported. The output buffer must be at least as long as
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The \fIlength\fP argument specifies the number of 16-bit data units in the
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input string; a negative value specifies a zero-terminated string.
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If \fIbyte_order\fP is NULL, it is assumed that the string starts off in host
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byte order. This may be changed by byte-order marks (BOMs) anywhere in the
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string (commonly as the first character).
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If \fIbyte_order\fP is not NULL, a non-zero value of the integer to which it
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points means that the input starts off in host byte order, otherwise the
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opposite order is assumed. Again, BOMs in the string can change this. The final
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byte order is passed back at the end of processing.
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If \fIkeep_boms\fP is not zero, byte-order mark characters (0xfeff) are copied
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into the output string. Otherwise they are discarded.
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The result of the function is the number of 16-bit units placed into the output
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buffer, including the zero terminator if the string was zero-terminated.
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.SH "SUBJECT STRING OFFSETS"
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The offsets within subject strings that are returned by the matching functions
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are in 16-bit units rather than bytes.
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.SH "NAMED SUBPATTERNS"
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The name-to-number translation table that is maintained for named subpatterns
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uses 16-bit characters. The \fBpcre16_get_stringtable_entries()\fP function
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returns the length of each entry in the table as the number of 16-bit data
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There are two new general option names, PCRE_UTF16 and PCRE_NO_UTF16_CHECK,
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which correspond to PCRE_UTF8 and PCRE_NO_UTF8_CHECK in the 8-bit library. In
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fact, these new options define the same bits in the options word.
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For the \fBpcre16_config()\fP function there is an option PCRE_CONFIG_UTF16
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that returns 1 if UTF-16 support is configured, otherwise 0. If this option is
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given to \fBpcre_config()\fP, or if the PCRE_CONFIG_UTF8 option is given to
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\fBpcre16_config()\fP, the result is the PCRE_ERROR_BADOPTION error.
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.SH "CHARACTER CODES"
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In 16-bit mode, when PCRE_UTF16 is not set, character values are treated in the
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same way as in 8-bit, non UTF-8 mode, except, of course, that they can range
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from 0 to 0xffff instead of 0 to 0xff. Character types for characters less than
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0xff can therefore be influenced by the locale in the same way as before.
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Characters greater than 0xff have only one case, and no "type" (such as letter
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In UTF-16 mode, the character code is Unicode, in the range 0 to 0x10ffff, with
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the exception of values in the range 0xd800 to 0xdfff because those are
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"surrogate" values that are used in pairs to encode values greater than 0xffff.
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A UTF-16 string can indicate its endianness by special code knows as a
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byte-order mark (BOM). The PCRE functions do not handle this, expecting strings
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to be in host byte order. A utility function called
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\fBpcre16_utf16_to_host_byte_order()\fP is provided to help with this (see
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The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16 correspond to
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their 8-bit counterparts. The error PCRE_ERROR_BADMODE is given when a compiled
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pattern is passed to a function that processes patterns in the other
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mode, for example, if a pattern compiled with \fBpcre_compile()\fP is passed to
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There are new error codes whose names begin with PCRE_UTF16_ERR for invalid
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UTF-16 strings, corresponding to the PCRE_UTF8_ERR codes for UTF-8 strings that
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are described in the section entitled
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.\" HTML <a href="pcreapi.html#badutf8reasons">
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"Reason codes for invalid UTF-8 strings"
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page. The UTF-16 errors are:
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PCRE_UTF16_ERR1 Missing low surrogate at end of string
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PCRE_UTF16_ERR2 Invalid low surrogate follows high surrogate
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PCRE_UTF16_ERR3 Isolated low surrogate
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PCRE_UTF16_ERR4 Invalid character 0xfffe
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If there is an error while compiling a pattern, the error text that is passed
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back by \fBpcre16_compile()\fP or \fBpcre16_compile2()\fP is still an 8-bit
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character string, zero-terminated.
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The \fIsubject\fP and \fImark\fP fields in the callout block that is passed to
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a callout function point to 16-bit vectors.
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The \fBpcretest\fP program continues to operate with 8-bit input and output
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files, but it can be used for testing the 16-bit library. If it is run with the
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command line option \fB-16\fP, patterns and subject strings are converted from
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8-bit to 16-bit before being passed to PCRE, and the 16-bit library functions
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are used instead of the 8-bit ones. Returned 16-bit strings are converted to
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8-bit for output. If the 8-bit library was not compiled, \fBpcretest\fP
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defaults to 16-bit and the \fB-16\fP option is ignored.
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When PCRE is being built, the \fBRunTest\fP script that is called by "make
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check" uses the \fBpcretest\fP \fB-C\fP option to discover which of the 8-bit
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and 16-bit libraries has been built, and runs the tests appropriately.
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.SH "NOT SUPPORTED IN 16-BIT MODE"
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Not all the features of the 8-bit library are available with the 16-bit
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library. The C++ and POSIX wrapper functions support only the 8-bit library,
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and the \fBpcregrep\fP program is at present 8-bit only.
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University Computing Service
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Cambridge CB2 3QH, England.
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Last updated: 08 January 2012
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Copyright (c) 1997-2012 University of Cambridge.
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doc/pcre16.3
