LazFileCache unit

Implements a caching mechanism for file and directory state information.

lazfilecache.pas implement a caching mechanism used for file and directory state information. It is used in the implementation of the Lazarus IDE, and in the LCL package system.

lazfilecache.pas is part of the LazUtils package.

Classes and records

`TFileStateCache`	class	Implements a state caching mechanism for files and directories.
`TFileStateCacheItem`	class	Contains information about a file or directory in the state caching mechanism.

Procedures and functions

`CompareFilenameWithFileStateCacheItem`	function	Compares a value to a file name in a TFileStateCacheItem instance.
`CompareFileStateItems`	function	Gets the relative order for the file names in the specified TFileStateCacheItem entries.
`DirectoryIsWritableCached`	function	Gets the Directory is Writable flag value for the specified path.
`DirPathExistsCached`	function	Gets the Path Exists flag value for the specified directory path.
`FileAgeCached`	function	Gets the file age for the specified file or directory.
`FileExistsCached`	function	Gets the File Exists flag value for the specified file name.
`FileIsExecutableCached`	function	Gets the File is Executable flag value for the specified file name.
`FileIsReadableCached`	function	Gets the File is Readable flag value for the specified file name.
`FileIsTextCached`	function	Gets the File is Text flag for the specified file name.
`FileIsWritableCached`	function	Gets the File is Writable flag value for the specified file name.
`GetPhysicalFilenameCached`	function	Gets the physical file name for the specified file or directory name.
`InvalidateFileStateCache`	procedure	Invalidates one or more items in the state cache.
`LUIncreaseChangeStamp`	procedure	Increments the specified Integer timestamp value.
`LUIncreaseChangeStamp64`	procedure	Increments the specified Int64 timestamp value.

Types

`TFileStateCacheItemFlag`	enumeration	Represents flag values used for files or directories in the state caching mechanism.
`TFileStateCacheItemFlags`	set	Set type used to store TFileStateCacheItemFlag enumeration values.
`TOnChangeFileStateTimeStamp`	procedure type	Specifies an event handler signalled when the timestamp for a cached item is changed.
`TOnFileAgeCached`	procedure type	Specifies an event handler signalled to get the file age for an item in the cache.
`TOnFileExistsCached`	procedure type	Specifies an event handler signalled to get the "file exists" flag for an item in the cache.

Constants

`LUInvalidChangeStamp`	constant	Integer value used as the invalid timestamp value for the cache mechanism.
`LUInvalidChangeStamp64`	constant	Int64 value used as the invalid timestamp value for the cache mechanism.

Variables

`FileStateCache`	variable	Unit global variable with the class instance for the state caching mechanism.
`OnFileAgeCached`	variable	Event handler signalled to get the file age for the specified file name.
`OnFileExistsCached`	variable	Event handler signalled to get the File Exists flag for the specified file name.

Uses

An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.