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Diffstat (limited to 'doc/ref/api-data.texi')
-rwxr-xr-x | doc/ref/api-data.texi | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/doc/ref/api-data.texi b/doc/ref/api-data.texi index 75e5e687a..82982e94b 100755 --- a/doc/ref/api-data.texi +++ b/doc/ref/api-data.texi @@ -3969,6 +3969,74 @@ is larger than @var{max_len}, only @var{max_len} bytes have been stored and you probably need to try again with a larger buffer. @end deftypefn +For most situations, string conversion should occur using the current +locale, such as with the functions above. But there may be cases where +one wants to convert strings from a character encoding other than the +locale's character encoding. For these cases, the lower-level functions +@code{scm_to_stringn} and @code{scm_from_stringn} are provided. These +functions should seldom be necessary if one is properly using locales. + +@deftp {C Type} scm_t_string_failed_conversion_handler +This is an enumerated type that can take one of three values: +@code{SCM_FAILED_CONVERSION_ERROR}, +@code{SCM_FAILED_CONVERSION_QUESTION_MARK}, and +@code{SCM_FAILED_CONVERSION_ESCAPE_SEQUENCE}. They are used to indicate +a strategy for handling characters that cannot be converted to or from a +given character encoding. @code{SCM_FAILED_CONVERSION_ERROR} indicates +that a conversion should throw an error if some characters cannot be +converted. @code{SCM_FAILED_CONVERSION_QUESTION_MARK} indicates that a +conversion should replace unconvertable characters with the question +mark character. And, @code{SCM_FAILED_CONVERSION_ESCAPE_SEQUENCE} +requests that a conversion should replace an unconvertable character +with an escape sequence. + +While all three strategies apply when converting Scheme strings to C, +only @code{SCM_FAILED_CONVERSION_ERROR} and +@code{SCM_FAILED_CONVERSION_QUESTION_MARK} can be used when converting C +strings to Scheme. +@end deftp + +@deftypefn {C Function} char *scm_to_stringn (SCM str, size_t *lenp, const char *encoding, scm_t_string_failed_conversion_handler handler) +This function returns a newly allocated C string from the Guile string +@var{str}. The length of the string will be returned in @var{lenp}. +The character encoding of the C string is passed as the ASCII, +null-terminated C string @var{encoding}. The @var{handler} parameter +gives a strategy for dealing with characters that cannot be converted +into @var{encoding}. + +If @var{lenp} is NULL, this function will return a null-terminated C +string. It will throw an error if the string contains a null +character. +@end deftypefn + +@deftypefn {C Function} SCM scm_from_stringn (const char *str, size_t len, const char *encoding, scm_t_string_failed_conversion_handler handler) +This function returns a scheme string from the C string @var{str}. The +length of the C string is input as @var{len}. The encoding of the C +string is passed as the ASCII, null-terminated C string @code{encoding}. +The @var{handler} parameters suggests a strategy for dealing with +unconvertable characters. +@end deftypefn + +ISO-8859-1 is the most common 8-bit character encoding. This encoding +is also referred to as the Latin-1 encoding. The following two +conversion functions are provided to convert between Latin-1 C strings +and Guile strings. + +@deftypefn {C Function} SCM scm_from_latin1_stringn (const char *str, size_t len) +This function returns a scheme string from an ISO-8859-1-encoded C +string @var{str} of length @var{len}. +@end deftypefn + +@deftypefn {C function} char * scm_to_latin1_stringn (SCM str, size_t *lenp) +This function returns a newly allocated, ISO-8859-1-encoded C string +from the scheme string @var{str}. An error will be thrown if the scheme +string cannot be converted to the ISO-8859-1 encoding. If @var{lenp} is +@code{NULL}, the returned C string will be null terminated, and an error +will be thrown if the C string would otherwise contain null +characters. If @var{lenp} is not NULL, the length of the string is +returned in @var{lenp}, and the string is not null terminated. +@end deftypefn + @node String Internals @subsubsection String Internals |