+ * Regular expression matching within the buffer.
+ *
+ * Formatting: SILC_STR_REGEX(char *regex, SilcBufferRegexFlags flags)
+ * Unformatting: SILC_STR_REGEX(char *regex, SilcBufferRegexFlags flags)
+ *
+ * SILC_STR_REGEX can be used to do regular expression matching within
+ * the SilcBuffer. When the string in the buffer matches the regular
+ * expression the position of the buffer is advanced to the position of
+ * the first match (rest of the buffer remains intact). If the regular
+ * expression does not match it is skipped, unless the flags specify
+ * otherwise. If flags are not needed they can be set to 0.
+ *
+ * In addition of matching regular expressions it can be used in a
+ * Stream Editor (sed) and Awk like fashion. The regular expression can be
+ * matched and then edited by any of the SILC_STR_* macros. The flags
+ * can be used to perform complex operations on the data. Some sed
+ * features that cannot be directly done with the flags can be done with
+ * SILC_STR_FUNC and other macros (the SILC_STR_FUNC could do anything
+ * after the match).
+ *
+ * The SILC_STR_REGEX itself is used as an opening of a block of encoding
+ * macros and must be closed with SILC_STR_END. This means that for
+ * each SILC_STR_REGEX there must be one SILC_STR_END. See examples for
+ * more information.
+ *
+ * The SILC_STR_REGEX can be used in buffer unformatting also to do
+ * string matching and parsing, but not editing, except with SILC_STR_FUNC
+ * macro, which can do anything caller wants.
+ *
+ * Typically the following encoding macros are used with SILC_STR_REGEX:
+ * SILC_STR_REPLACE, SILC_STR_STRING and SILC_STR_FUNC. If you use
+ * SILC_STR_REPLACE always set SILC_STR_REGEX_INCLUSIVE.
+ *
+ * EXAMPLE
+ *
+ * // sed 's/foo/bar/', replace first foo with bar
+ * silc_buffer_format(buffer,
+ * SILC_STR_REGEX("foo", 0),
+ * SILC_STR_STRING("bar"),
+ * SILC_STR_END, SILC_STR_END);
+ *
+ * // sed 's/foo/barbar/g', replace all foo's with barbar, without
+ * // overwriting any data in the buffer, but appending it. The match
+ * // must be inclusive to make appending work.
+ * silc_buffer_format(buffer,
+ * SILC_STR_REGEX("foo", SILC_STR_REGEX_ALL |
+ * SILC_STR_REGEX_INCLUSIVE),
+ * SILC_STR_REPLACE("barbar", 5),
+ * SILC_STR_END, SILC_STR_END);
+ *
+ * // sed 's/foo/B/', replace foo with B, deleting rest of the match from
+ * // the buffer. The match must be inclusive to make deleting work.
+ * silc_buffer_format(buffer,
+ * SILC_STR_REGEX("foo", SILC_STR_REGEX_ALL |
+ * SILC_STR_REGEX_INCLUSIVE),
+ * SILC_STR_REPLACE("B", 1),
+ * SILC_STR_END, SILC_STR_END);
+ *
+ * // sed '/baz/s/foo/bar/g, replace all foo's with bar on lines with baz
+ * silc_buffer_format(buffer,
+ * SILC_STR_REGEX("baz", SILC_STR_REGEX_NL),
+ * SILC_STR_REGEX("foo", SILC_STR_REGEX_ALL),
+ * SILC_STR_STRING("bar"),
+ * SILC_STR_END,
+ * SILC_STR_END, SILC_STR_END);
+ *
+ * // Print all lines that start with 'R'
+ * int print(SilcStack stack, SilcBuffer buf, void *value, void *context)
+ * {
+ * return fwrite(silc_buffer_data(buf), 1, silc_buffer_len(buf), stdout);
+ * }
+ *
+ * silc_buffer_unformat(buffer,
+ * SILC_STR_REGEX("^R", SILC_STR_REGEX_NL),
+ * SILC_STR_FUNC(print, NULL, NULL),
+ * SILC_STR_END, SILC_STR_END);