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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) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * src/include/lib/stringinfo.h * *------------------------------------------------------------------------- */ #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. * cursor is initialized to zero by makeStringInfo or initStringInfo, * but is not otherwise touched by the stringinfo.c routines. * Some routines use it to scan through a StringInfo. *------------------------- */ typedef struct StringInfoData { char *data; int len; int maxlen; int cursor; } 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); /*------------------------ * resetStringInfo * Clears the current content of the StringInfo, if any. The * StringInfo remains valid. */ extern void resetStringInfo(StringInfo str); /*------------------------ * appendStringInfo * Format text data under the control of fmt (an sprintf-style 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,...) /* This extension allows gcc to check the format string */ __attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 3))); /*------------------------ * appendStringInfoVA * Attempt to format text data under the control of fmt (an sprintf-style * format string) and append it to whatever is already in str. If successful * return true; if not (because there's not enough space), return false * without modifying str. Typically the caller would enlarge str and retry * on false return --- see appendStringInfo for standard usage pattern. */ extern bool appendStringInfoVA(StringInfo str, const char *fmt, va_list args) __attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 0))); /*------------------------ * appendStringInfoString * Append a null-terminated string to str. * Like appendStringInfo(str, "%s", s) but faster. */ extern void appendStringInfoString(StringInfo str, const char *s); /*------------------------ * 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')) /*------------------------ * appendStringInfoSpaces * Append a given number of spaces to str. */ extern void appendStringInfoSpaces(StringInfo str, int count); /*------------------------ * appendBinaryStringInfo * Append arbitrary binary data to a StringInfo, allocating more space * if necessary. */ extern void appendBinaryStringInfo(StringInfo str, const char *data, int datalen); /*------------------------ * enlargeStringInfo * Make sure a StringInfo's buffer can hold at least 'needed' more bytes. */ extern void enlargeStringInfo(StringInfo str, int needed); #endif /* STRINGINFO_H */