SQLite源码剖析(6)

lanxi256

　　/*
　　** Add the ability to override 'extern'
　　*/
　　//定义extern的宏，可使用SQLITE_EXTERN来完成extern功能
　　#ifndef SQLITE_EXTERN
　　# define SQLITE_EXTERN extern
　　#endif
　　//定义SQLITE_API宏
　　#ifndef SQLITE_API
　　# define SQLITE_API
　　#endif
　　 
　　 
　　/* no-op宏经常在接口前标记那些实验性的和不推荐的接口。新应用程序最好
　　**不使用不推荐的接口，它们支持向后兼容。程序员必须意识到实验性接口
　　**会在某个版本中改变
　　** These no-op macros are used in front of interfaces to mark those
　　** interfaces as either deprecated or experimental.  New applications
　　** should not use deprecated interfaces - they are support for backwards
　　** compatibility only.  Application writers should be aware that
　　** experimental interfaces are subject to change in point releases.
　　**这些宏在他们需要时，能实现编译器魔法compiler magic警告信息，
　　**编译器魔法最终产生BUG报告，编译器会试着使用noop宏。
　　** These macros used to resolve to various kinds of compiler magic that
　　** would generate warning messages when they were used.  But that
　　** compiler magic ended up generating such a flurry of bug reports
　　** that we have taken it all out and gone back to using simple
　　** noop macros.
　　*/
　　#define SQLITE_DEPRECATED
　　#define SQLITE_EXPERIMENTAL
　　 
　　/*
　　** Ensure these symbols were not defined by some previous header file.
　　*/
　　//如果SQLITE_VERSION、SQLITE_VERSION_NUMBER标志已经定义，则取消
　　#ifdef SQLITE_VERSION
　　# undef SQLITE_VERSION
　　#endif
　　#ifdef SQLITE_VERSION_NUMBER
　　# undef SQLITE_VERSION_NUMBER
　　#endif
　　 
　　/*
　　** CAPI3REF: Compile-Time Library Version Numbers
　　** SQLITE_VERSION 宏为版本号，[X.Y.Z的SQLITE版本号中,X是主版本号，Y
　　**是次版本号，Z是发行号
　　** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header
　　** evaluates to a string literal that is the SQLite version in the
　　** format "X.Y.Z" where X is the major version number (always 3 for
　　** SQLite3) and Y is the minor version number and Z is the release number.)^
　　** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves
　　** to an integer with the value (X*1000000 + Y*1000 + Z) where X, Y,
　　**and Z are the same numbers used in [SQLITE_VERSION].)^
　　** SQLITE_VERSION_NUMBER根据SQLITE_VERSION中版本号计算一个
　　**整数（X*1000000 + Y*1000 + Z）
　　** The SQLITE_VERSION_NUMBER for any given release of SQLite will also
　　** be larger than the release from which it is derived.  Either Y will
　　** be held constant and Z will be incremented or else Y will be incremented
　　** and Z will be reset to zero.
　　**
　　** Since version 3.6.18, SQLite source code has been stored in the
　　** <a href="http://www.fossil-scm.org/">Fossil configuration management
　　** system</a>.  ^The SQLITE_SOURCE_ID macro evalutes to
　　** a string which identifies a particular check-in of SQLite
　　** within its configuration management system.  ^The SQLITE_SOURCE_ID
　　** string contains the date and time of the check-in (UTC) and an SHA1
　　** hash of the entire source tree.
　　** SQLITE_SOURCE_ID 为一个字符串，为SQLITE配置管理系统中的check-in
　　**详情包含check-in的日期和时间以及整个源码树的SHA1哈希
　　** See also: [sqlite3_libversion()],
　　** [sqlite3_libversion_number()], [sqlite3_sourceid()],
　　** [sqlite_version()] and [sqlite_source_id()].
　　*/
　　//定义版本号，并计算SQLITE_VERSION_NUMBER
　　#define SQLITE_VERSION        "3.6.23.1"
　　#define SQLITE_VERSION_NUMBER 3006023
　　#define SQLITE_SOURCE_ID      "2010-03-26 22:28:06 b078b588d617e07886ad156e9f54ade6d823568e"
　　 
　　/*
　　** CAPI3REF: Run-Time Library Version Numbers
　　** KEYWORDS: sqlite3_version, sqlite3_sourceid
　　** 这些接口通过库而不是头文件提供了
　　*SQLITE_VERSION、SQLITE_VERSION_NUMBER以**及SQLITE_SOURCE_ID宏
　　**的相同信息
　　** These interfaces provide the same information as the [SQLITE_VERSION],
　　** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
　　** but are associated with the library instead of the header file.  ^(Cautious
　　** programmers might include assert() statements in their application to
　　** verify that values returned by these interfaces match the macros in
　　** the header, and thus insure that the application is
　　** compiled with matching library and header files.
　　**可小心地通过包含以下的assert()声明，在应用程序核实匹配头文件中宏的
　　**这些接口，以确保应用程序使用相匹配的库和头文件编译
　　** <blockquote><pre>
　　** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
　　** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );
　　** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
　　** </pre></blockquote>)^
　　
　　
　　
　　
　　声明：本SQLite源码剖析系列为刘兴(http://deepfuture.iyunv.com/)原创，未经笔者授权，任何人和机构不能转载