postgres.h

从一个开源软件中摘取的正则表达式模块

/*-------------------------------------------------------------------------
 *
 * postgres.h
 *	  Primary include file for PostgreSQL server .c files
 *
 * This should be the first file included by PostgreSQL backend modules.
 * Client-side code should include postgres_fe.h instead.
 *
 *
 * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
 * Portions Copyright (c) 1995, Regents of the University of California
 *
 * $PostgreSQL: pgsql/src/include/postgres.h,v 1.88 2008/01/01 19:45:56 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
/*
 *----------------------------------------------------------------
 *	 TABLE OF CONTENTS
 *
 *		When adding stuff to this file, please try to put stuff
 *		into the relevant section, or add new sections as appropriate.
 *
 *	  section	description
 *	  -------	------------------------------------------------
 *		1)		variable-length datatypes (TOAST support)
 *		2)		datum type + support macros
 *		3)		exception handling definitions
 *		4)		genbki macros used by catalog/pg_xxx.h files
 *
 *	 NOTES
 *
 *	In general, this file should contain declarations that are widely needed
 *	in the backend environment, but are of no interest outside the backend.
 *
 *	Simple type definitions live in c.h, where they are shared with
 *	postgres_fe.h.	We do that since those type definitions are needed by
 *	frontend modules that want to deal with binary data transmission to or
 *	from the backend.  Type definitions in this file should be for
 *	representations that never escape the backend, such as Datum or
 *	TOASTed varlena objects.
 *
 *----------------------------------------------------------------
 */
#ifndef POSTGRES_H
#define POSTGRES_H

#include "c.h"


/* ----------------------------------------------------------------
 *				Section 1:	variable-length datatypes (TOAST support)
 * ----------------------------------------------------------------
 */

/*
 * struct varatt_external is a "TOAST pointer", that is, the information
 * needed to fetch a stored-out-of-line Datum.	The data is compressed
 * if and only if va_extsize < va_rawsize - VARHDRSZ.  This struct must not
 * contain any padding, because we sometimes compare pointers using memcmp.
 *
 * Note that this information is stored unaligned within actual tuples, so
 * you need to memcpy from the tuple into a local struct variable before
 * you can look at these fields!  (The reason we use memcmp is to avoid
 * having to do that just to detect equality of two TOAST pointers...)
 */
/*
 * These structs describe the header of a varlena object that may have been
 * TOASTed.  Generally, don't reference these structs directly, but use the
 * macros below.
 *
 * We use separate structs for the aligned and unaligned cases because the
 * compiler might otherwise think it could generate code that assumes
 * alignment while touching fields of a 1-byte-header varlena.
 */
typedef union
{
	struct						/* Normal varlena (4-byte length) */
	{
		uint32		va_header;
		char		va_data[1];
	}		va_4byte;
	struct						/* Compressed-in-line format */
	{
		uint32		va_header;
		uint32		va_rawsize; /* Original data size (excludes header) */
		char		va_data[1]; /* Compressed data */
	}		va_compressed;
} varattrib_4b;

typedef struct
{
	uint8		va_header;
	char		va_data[1];		/* Data begins here */
} varattrib_1b;

typedef struct
{
	uint8		va_header;		/* Always 0x80 or 0x01 */
	uint8		va_len_1be;		/* Physical length of datum */
	char		va_data[1];		/* Data (for now always a TOAST pointer) */
} varattrib_1b_e;

/*
 * Bit layouts for varlena headers on big-endian machines:
 *
 * 00xxxxxx 4-byte length word, aligned, uncompressed data (up to 1G)
 * 01xxxxxx 4-byte length word, aligned, *compressed* data (up to 1G)
 * 10000000 1-byte length word, unaligned, TOAST pointer
 * 1xxxxxxx 1-byte length word, unaligned, uncompressed data (up to 126b)
 *
 * Bit layouts for varlena headers on little-endian machines:
 *
 * xxxxxx00 4-byte length word, aligned, uncompressed data (up to 1G)
 * xxxxxx10 4-byte length word, aligned, *compressed* data (up to 1G)
 * 00000001 1-byte length word, unaligned, TOAST pointer
 * xxxxxxx1 1-byte length word, unaligned, uncompressed data (up to 126b)
 *
 * The "xxx" bits are the length field (which includes itself in all cases).
 * In the big-endian case we mask to extract the length, in the little-endian
 * case we shift.  Note that in both cases the flag bits are in the physically
 * first byte.	Also, it is not possible for a 1-byte length word to be zero;
 * this lets us disambiguate alignment padding bytes from the start of an
 * unaligned datum.  (We now *require* pad bytes to be filled with zero!)
 */

/*
 * Endian-dependent macros.  These are considered internal --- use the
 * external macros below instead of using these directly.
 *
 * Note: IS_1B is true for external toast records but VARSIZE_1B will return 0
 * for such records. Hence you should usually check for IS_EXTERNAL before
 * checking for IS_1B.
 */

#ifdef WORDS_BIGENDIAN

#define VARATT_IS_4B(PTR) \
	((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x00)
#define VARATT_IS_4B_U(PTR) \
	((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x00)
#define VARATT_IS_4B_C(PTR) \
	((((varattrib_1b *) (PTR))->va_header & 0xC0) == 0x40)
#define VARATT_IS_1B(PTR) \
	((((varattrib_1b *) (PTR))->va_header & 0x80) == 0x80)
#define VARATT_IS_1B_E(PTR) \
	((((varattrib_1b *) (PTR))->va_header) == 0x80)
#define VARATT_NOT_PAD_BYTE(PTR) \
	(*((uint8 *) (PTR)) != 0)

/* VARSIZE_4B() should only be used on known-aligned data */
#define VARSIZE_4B(PTR) \
	(((varattrib_4b *) (PTR))->va_4byte.va_header & 0x3FFFFFFF)
#define VARSIZE_1B(PTR) \
	(((varattrib_1b *) (PTR))->va_header & 0x7F)
#define VARSIZE_1B_E(PTR) \
	(((varattrib_1b_e *) (PTR))->va_len_1be)

#define SET_VARSIZE_4B(PTR,len) \
	(((varattrib_4b *) (PTR))->va_4byte.va_header = (len) & 0x3FFFFFFF)
#define SET_VARSIZE_4B_C(PTR,len) \
	(((varattrib_4b *) (PTR))->va_4byte.va_header = ((len) & 0x3FFFFFFF) | 0x40000000)
#define SET_VARSIZE_1B(PTR,len) \
	(((varattrib_1b *) (PTR))->va_header = (len) | 0x80)
#define SET_VARSIZE_1B_E(PTR,len) \
	(((varattrib_1b_e *) (PTR))->va_header = 0x80, \
	 ((varattrib_1b_e *) (PTR))->va_len_1be = (len))
#else							/* !WORDS_BIGENDIAN */

#define VARATT_IS_4B(PTR) \
	((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x00)
#define VARATT_IS_4B_U(PTR) \
	((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x00)
#define VARATT_IS_4B_C(PTR) \
	((((varattrib_1b *) (PTR))->va_header & 0x03) == 0x02)
#define VARATT_IS_1B(PTR) \
	((((varattrib_1b *) (PTR))->va_header & 0x01) == 0x01)
#define VARATT_IS_1B_E(PTR) \
	((((varattrib_1b *) (PTR))->va_header) == 0x01)
#define VARATT_NOT_PAD_BYTE(PTR) \
	(*((uint8 *) (PTR)) != 0)

/* VARSIZE_4B() should only be used on known-aligned data */
#define VARSIZE_4B(PTR) \
	((((varattrib_4b *) (PTR))->va_4byte.va_header >> 2) & 0x3FFFFFFF)
#define VARSIZE_1B(PTR) \
	((((varattrib_1b *) (PTR))->va_header >> 1) & 0x7F)
#define VARSIZE_1B_E(PTR) \
	(((varattrib_1b_e *) (PTR))->va_len_1be)

#define SET_VARSIZE_4B(PTR,len) \
	(((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2))
#define SET_VARSIZE_4B_C(PTR,len) \
	(((varattrib_4b *) (PTR))->va_4byte.va_header = (((uint32) (len)) << 2) | 0x02)
#define SET_VARSIZE_1B(PTR,len) \
	(((varattrib_1b *) (PTR))->va_header = (((uint8) (len)) << 1) | 0x01)
#define SET_VARSIZE_1B_E(PTR,len) \
	(((varattrib_1b_e *) (PTR))->va_header = 0x01, \
	 ((varattrib_1b_e *) (PTR))->va_len_1be = (len))
#endif   /* WORDS_BIGENDIAN */

#define VARHDRSZ_SHORT			1
#define VARATT_SHORT_MAX		0x7F
#define VARATT_CAN_MAKE_SHORT(PTR) \
	(VARATT_IS_4B_U(PTR) && \
	 (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) <= VARATT_SHORT_MAX)
#define VARATT_CONVERTED_SHORT_SIZE(PTR) \
	(VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT)

#define VARHDRSZ_EXTERNAL		2

#define VARDATA_4B(PTR)		(((varattrib_4b *) (PTR))->va_4byte.va_data)
#define VARDATA_4B_C(PTR)	(((varattrib_4b *) (PTR))->va_compressed.va_data)
#define VARDATA_1B(PTR)		(((varattrib_1b *) (PTR))->va_data)
#define VARDATA_1B_E(PTR)	(((varattrib_1b_e *) (PTR))->va_data)

#define VARRAWSIZE_4B_C(PTR) \
	(((varattrib_4b *) (PTR))->va_compressed.va_rawsize)

/* Externally visible macros */

/*
 * VARDATA, VARSIZE, and SET_VARSIZE are the recommended API for most code
 * for varlena datatypes.  Note that they only work on untoasted, 4-byte-header Datums!
 * VARDATA,VARSize 和 SET_WARSIZE是 arlena数据类型推荐使用的API。
 *
 * Code that wants to use 1-byte-header values without detoasting should
 * use VARSIZE_ANY/VARSIZE_ANY_EXHDR/VARDATA_ANY.  The other macros here
 * VARSIZE_ANY 获取指定指针的数据长度
 * VARSIZE_ANY_EXHER
 * should usually be used only by tuple assembly/disassembly code and
 * code that specifically wants to work with still-toasted Datums.
 *
 * WARNING: It is only safe to use VARDATA_ANY() -- typically with
 * PG_DETOAST_DATUM_PACKED() -- if you really don't care about the alignment.
 * Either because you're working with something like text where the alignment
 * doesn't matter or because you're not going to access its constituent parts
 * and just use things like memcpy on it anyways.
 */
#define VARDATA(PTR)						VARDATA_4B(PTR)
#define VARSIZE(PTR)						VARSIZE_4B(PTR)

#define VARSIZE_SHORT(PTR)					VARSIZE_1B(PTR)
#define VARDATA_SHORT(PTR)					VARDATA_1B(PTR)

#define VARSIZE_EXTERNAL(PTR)				VARSIZE_1B_E(PTR)
#define VARDATA_EXTERNAL(PTR)				VARDATA_1B_E(PTR)

#define VARATT_IS_COMPRESSED(PTR)			VARATT_IS_4B_C(PTR)
#define VARATT_IS_EXTERNAL(PTR)				VARATT_IS_1B_E(PTR)
#define VARATT_IS_SHORT(PTR)				VARATT_IS_1B(PTR)
#define VARATT_IS_EXTENDED(PTR)				(!VARATT_IS_4B_U(PTR))

#define SET_VARSIZE(PTR, len)				SET_VARSIZE_4B(PTR, len)
#define SET_VARSIZE_SHORT(PTR, len)			SET_VARSIZE_1B(PTR, len)
#define SET_VARSIZE_COMPRESSED(PTR, len)	SET_VARSIZE_4B_C(PTR, len)
#define SET_VARSIZE_EXTERNAL(PTR, len)		SET_VARSIZE_1B_E(PTR, len)

#define VARSIZE_ANY(PTR) \
	(VARATT_IS_1B_E(PTR) ? VARSIZE_1B_E(PTR) : \
	 (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR) : \
	  VARSIZE_4B(PTR)))

#define VARSIZE_ANY_EXHDR(PTR) \
	(VARATT_IS_1B_E(PTR) ? VARSIZE_1B_E(PTR)-VARHDRSZ_EXTERNAL : \
	 (VARATT_IS_1B(PTR) ? VARSIZE_1B(PTR)-VARHDRSZ_SHORT : \
	  VARSIZE_4B(PTR)-VARHDRSZ))

/* caution: this will not work on an external or compressed-in-line Datum */
/* caution: this will return a possibly unaligned pointer */
#define VARDATA_ANY(PTR) \
	 (VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR))


/* ----------------------------------------------------------------
 *				Section 2:	datum type + support macros
 * ----------------------------------------------------------------
 */

/*
 * Port Notes:
 *	Postgres makes the following assumption about machines:
 *
 *	sizeof(Datum) == sizeof(long) >= sizeof(void *) >= 4
 *
 *	Postgres also assumes that
 *
 *	sizeof(char) == 1
 *
 *	and that
 *
 *	sizeof(short) == 2
 *
 * When a type narrower than Datum is stored in a Datum, we place it in the
 * low-order bits and are careful that the DatumGetXXX macro for it discards
 * the unused high-order bits (as opposed to, say, assuming they are zero).
 * This is needed to support old-style user-defined functions, since depending
 * on architecture and compiler, the return value of a function returning char
 * or short may contain garbage when called as if it returned Datum.
 */

typedef unsigned long Datum;	/* XXX sizeof(long) >= sizeof(void *) */









/* ----------------------------------------------------------------
 *				Section 3:	exception handling definitions
 *							Assert, Trap, etc macros
 * ----------------------------------------------------------------
 */

extern PGDLLIMPORT bool assert_enabled;

/*
 * USE_ASSERT_CHECKING, if defined, turns on all the assertions.
 * - plai  9/5/90
 *
 * It should _NOT_ be defined in releases or in benchmark copies
 */

/*
 * Trap
 *		Generates an exception if the given condition is true.
 */
#define Trap(condition, errorType) \
	do { \
		if ((assert_enabled) && (condition)) \
			ExceptionalCondition(CppAsString(condition), (errorType), \
								 __FILE__, __LINE__); \
	} while (0)

/*
 *	TrapMacro is the same as Trap but it's intended for use in macros:
 *
 *		#define foo(x) (AssertMacro(x != 0) && bar(x))
 *
 *	Isn't CPP fun?
 */
#define TrapMacro(condition, errorType) \
	((bool) ((! assert_enabled) || ! (condition) || \
			 (ExceptionalCondition(CppAsString(condition), (errorType), \
								   __FILE__, __LINE__))))

#ifndef USE_ASSERT_CHECKING
#define Assert(condition)
#define AssertMacro(condition)	((void)true)
#define AssertArg(condition)
#define AssertState(condition)
#else
#define Assert(condition) \
		Trap(!(condition), "FailedAssertion")

#define AssertMacro(condition) \
		((void) TrapMacro(!(condition), "FailedAssertion"))

#define AssertArg(condition) \
		Trap(!(condition), "BadArgument")

#define AssertState(condition) \
		Trap(!(condition), "BadState")
#endif   /* USE_ASSERT_CHECKING */

extern int ExceptionalCondition(const char *conditionName,
					 const char *errorType,
					 const char *fileName, int lineNumber);

/* ----------------------------------------------------------------
 *				Section 4: genbki macros used by catalog/pg_xxx.h files
 * ----------------------------------------------------------------
 */
#define CATALOG(name,oid)	typedef struct CppConcat(FormData_,name)

#define BKI_BOOTSTRAP
#define BKI_SHARED_RELATION
#define BKI_WITHOUT_OIDS

/* these need to expand into some harmless, repeatable declaration */
#define DATA(x)   extern int no_such_variable
#define DESCR(x)  extern int no_such_variable
#define SHDESCR(x) extern int no_such_variable


#endif   /* POSTGRES_H */