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/*-------------------------------------------------------------------------
*
* stringinfo.h
* Declarations/definitions for "StringInfo" functions.
*
* StringInfo provides an indefinitely-extensible string data type.
* It can be used to buffer either ordinary C strings (null-terminated text)
* or arbitrary binary data. All storage is allocated with palloc().
*
* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: stringinfo.h,v 1.18 2000/04/12 17:16:34 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef STRINGINFO_H
#define STRINGINFO_H
/*-------------------------
* StringInfoData holds information about an extensible string.
* data is the current buffer for the string (allocated with palloc).
* len is the current string length. There is guaranteed to be
* a terminating '\0' at data[len], although this is not very
* useful when the string holds binary data rather than text.
* maxlen is the allocated size in bytes of 'data', i.e. the maximum
* string size (including the terminating '\0' char) that we can
* currently store in 'data' without having to reallocate
* more space. We must always have maxlen > len.
*-------------------------
*/
typedef struct StringInfoData
{
char *data;
int len;
int maxlen;
} StringInfoData;
typedef StringInfoData *StringInfo;
/*------------------------
* There are two ways to create a StringInfo object initially:
*
* StringInfo stringptr = makeStringInfo();
* Both the StringInfoData and the data buffer are palloc'd.
*
* StringInfoData string;
* initStringInfo(&string);
* The data buffer is palloc'd but the StringInfoData is just local.
* This is the easiest approach for a StringInfo object that will
* only live as long as the current routine.
*
* To destroy a StringInfo, pfree() the data buffer, and then pfree() the
* StringInfoData if it was palloc'd. There's no special support for this.
*
* NOTE: some routines build up a string using StringInfo, and then
* release the StringInfoData but return the data string itself to their
* caller. At that point the data string looks like a plain palloc'd
* string.
*-------------------------
*/
/*------------------------
* makeStringInfo
* Create an empty 'StringInfoData' & return a pointer to it.
*/
extern StringInfo makeStringInfo(void);
/*------------------------
* initStringInfo
* Initialize a StringInfoData struct (with previously undefined contents)
* to describe an empty string.
*/
extern void initStringInfo(StringInfo str);
/*------------------------
* appendStringInfo
* Format text data under the control of fmt (an sprintf-like format string)
* and append it to whatever is already in str. More space is allocated
* to str if necessary. This is sort of like a combination of sprintf and
* strcat.
*/
extern void appendStringInfo(StringInfo str, const char *fmt,...);
/*------------------------
* appendStringInfoChar
* Append a single byte to str.
* Like appendStringInfo(str, "%c", ch) but much faster.
*/
extern void appendStringInfoChar(StringInfo str, char ch);
/*------------------------
* appendStringInfoCharMacro
* As above, but a macro for even more speed where it matters.
* Caution: str argument will be evaluated multiple times.
*/
#define appendStringInfoCharMacro(str,ch) \
(((str)->len + 1 >= (str)->maxlen) ? \
appendStringInfoChar(str, ch) : \
(void)((str)->data[(str)->len] = (ch), (str)->data[++(str)->len] = '\0'))
/*------------------------
* appendBinaryStringInfo
* Append arbitrary binary data to a StringInfo, allocating more space
* if necessary.
*/
extern void appendBinaryStringInfo(StringInfo str,
const char *data, int datalen);
#endif /* STRINGINFO_H */
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