<?xml version="1.0" encoding="UTF-8"?>
<!--

Documentation for LCL (Lazarus Component Library) and LazUtils (Lazarus 
Utilities) are published under the Creative Commons Attribution-ShareAlike 4.0 
International public license.

https://creativecommons.org/licenses/by-sa/4.0/legalcode.txt
file://../../cc-by-sa-4-0.txt

Copyright (c) 1997-2023, by the Lazarus Development Team.

-->
<fpdoc-descriptions>
<package name="lazutils">
<!--
====================================================================
LazFileCache
====================================================================
-->
<module name="LazFileCache">
<short>
Implements a caching mechanism for file and directory state information.
</short>
<descr>
<p>
<file>lazfilecache.pas</file> 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.
</p>
<p>
<file>lazfilecache.pas</file> is part of the <file>LazUtils</file> package.
</p>
</descr>

<!-- unresolved external references -->
<element name="Classes"/>
<element name="SysUtils"/>
<element name="Laz_AVL_Tree"/>
<element name="LazDbgLog"/>
<element name="LazFileUtils"/>

<element name="TFileStateCacheItemFlag">
<short>
Represents flag values used for files or directories in the
state caching mechanism.
</short>
<descr>
<p>
<var>TFileStateCacheItemFlag</var> is an enumerated type with values that
represent flags used for files or directories in the state caching mechanism.
Values from the enumeration are stored in the 
<var>TFileStateCacheItemFlags</var>
set type, and used in the implementation of the <var>TFileStateCacheItem</var>
class.
</p>
</descr>
<seealso>
<link id="TFileStateCacheItemFlags"/>
<link id="TFileStateCacheItem"/>
<link id="TFileStateCache"/>
</seealso>
</element>

<element name="TFileStateCacheItemFlag.fsciExists">
<short>File or directory exists.</short>
</element>

<element name="TFileStateCacheItemFlag.fsciDirectory">
<short>File exists and is a directory.</short>
</element>

<element name="TFileStateCacheItemFlag.fsciReadable">
<short>File is readable.</short>
</element>

<element name="TFileStateCacheItemFlag.fsciWritable">
<short>File is writable.</short>
</element>

<element name="TFileStateCacheItemFlag.fsciDirectoryReadable">
<short>File is a directory and can be searched.</short>
</element>

<element name="TFileStateCacheItemFlag.fsciDirectoryWritable">
<short>File is a directory and allows new files to be created.</short>
</element>

<element name="TFileStateCacheItemFlag.fsciText">
<short>File is a text (not an executable binary) file.</short>
</element>

<element name="TFileStateCacheItemFlag.fsciExecutable">
<short>File is an executable binary file.</short>
</element>

<element name="TFileStateCacheItemFlag.fsciAge">
<short>file age is valid.</short>
</element>

<element name="TFileStateCacheItemFlag.fsciPhysical">
<short>Physical file name for the file is valid.</short>
</element>

<element name="TFileStateCacheItemFlags">
<short>
Set type used to store TFileStateCacheItemFlag enumeration values.
</short>
<descr/>
<seealso>
<link id="TFileStateCacheItemFlag"/>
<link id="TFileStateCacheItem.Flags"/>
<link id="TFileStateCache"/>
</seealso>
</element>

<element name="TFileStateCacheItem">
<short>
Contains information about a file or directory in the state caching mechanism.
</short>
<descr>
<p>
<var>TFileStateCacheItem</var> is a class which contains information about a 
file or
directory in the state caching mechanism. TFileStateCacheItem has properties
used to represent a file or directory name (symbolic and physical), a 
timestamp,
and status flags.
</p>
<p>
TFileStateCacheItem is the type creates and stored in the internal AVL tree in
<var>TFileStateCache</var> using its <var>FindFile</var> method.
</p>
</descr>
<seealso>
<link id="TFileStateCache.FindFile"/>
</seealso>
</element>

<!-- private -->
<element name="TFileStateCacheItem.FAge"/>
<element name="TFileStateCacheItem.FFilename"/>
<element name="TFileStateCacheItem.FFlags"/>
<element name="TFileStateCacheItem.FTestedFlags"/>
<element name="TFileStateCacheItem.FTimeStamp"/>

<!-- public -->
<element name="TFileStateCacheItem.Create">
<short>Constructor for the class instance.</short>
<descr>
<p>
<var>Create</var> is the constructor for the class instance. It sets the
initial values for the following properties:
</p>
<dl>
<dt>Filename</dt>
<dd>Set to the value passed in TheFilename.</dd>
<dt>TimeStamp</dt>
<dd>Set to the value passed in NewTimeStamp.</dd>
</dl>
</descr>
<seealso>
<link id="TFileStateCacheItem.Filename"/>
<link id="TFileStateCacheItem.TimeStamp"/>
</seealso>
</element>

<element name="TFileStateCacheItem.Create.TheFilename">
<short>Name for the file or directory in the cache item.</short>
</element>

<element name="TFileStateCacheItem.Create.NewTimeStamp">
<short>Timestamp value for the file or directory.</short>
</element>

<element name="TFileStateCacheItem.CalcMemSize">
<short>Gets the memory size needed to store the class instance.</short>
<descr/>
<seealso>
<link id="TFileStateCacheItem.Filename"/>
<link id="TFileStateCacheItem.PhysicalFilename"/>
<link id="#rtl.system.TObject.InstanceSize">TObject.InstanceSize</link>
</seealso>
</element>

<element name="TFileStateCacheItem.CalcMemSize.Result">
<short>
Number of bytes needed to store the class instance and its assigned data.
</short>
</element>

<element name="TFileStateCacheItem.Filename">
<short>Name for the file or directory in the cache item.</short>
<descr/>
<seealso>
<link id="TFileStateCacheItem.PhysicalFilename"/>
<link id="TFileStateCacheItem.Flags"/>
</seealso>
</element>

<element name="TFileStateCacheItem.PhysicalFilename">
<short>Physical name for the file or directory in the cache item.</short>
<descr/>
<seealso>
<link id="TFileStateCacheItem.Filename"/>
<link id="TFileStateCacheItem.Flags"/>
</seealso>
</element>

<element name="TFileStateCacheItem.Flags">
<short>Contains status flags for the cached file or directory item.</short>
<descr/>
<seealso>
<link id="TFileStateCacheItem.TestedFlags"/>
<link id="TFileStateCache.Check"/>
</seealso>
</element>

<element name="TFileStateCacheItem.TestedFlags">
<short>
Contains status flags that have been tested for the cached item.
</short>
<descr/>
<seealso>
<link id="TFileStateCacheItem.Flags"/>
<link id="TFileStateCache.Check"/>
</seealso>
</element>

<element name="TFileStateCacheItem.TimeStamp">
<short>Timestamp for the cached item.</short>
<descr>
<p>
<var>Timestamp</var> is an <var>Int64</var> property with a timestamp value 
for
an item in the state caching mechanism. It is not actually a time value; it is
a counter that is assigned when the item is added to the TFileStateCache 
class.
It can be compared to the <var>Timestamp</var> value in the state cache to
determine when the item is potentially out-of-date.
</p>
<p>
Use <var>TFileStateCache.Timestamp</var> to determine when the cached item is
invalid.
</p>
</descr>
<seealso>
<link id="TFileStateCache.Timestamp"/>
<link id="TFileStateCache.IncreaseTimeStamp"/>
<link id="TFileStateCache.FindFile"/>
</seealso>
</element>

<element name="TFileStateCacheItem.Age">
<short>FileAge value for the file or directory.</short>
<descr>
<p>
<var>Age</var> is a <var>LongInt</var> property with the file age for the 
file or
directory in the cache item. The value for the property is assigned when the
TFileStateCache.FileAgeCached method is called, and contains the value 
returned
from the FileAge routine in <file>SysUtils</file>.
</p>
</descr>
<seealso>
<link id="TFileStateCache.FileAgeCached"/>
<link id="#rtl.sysutils.FileAge">FileAge</link>
</seealso>
</element>

<element name="TOnChangeFileStateTimeStamp">
<short>
Specifies an event handler signalled when the timestamp for a cached item
is changed.
</short>
<descr/>
<seealso/>
</element>

<element name="TOnChangeFileStateTimeStamp.Sender">
<short>Object instance for the event notification.</short>
</element>

<element name="TOnChangeFileStateTimeStamp.AFilename">
<short>Name for the affected file or directory.</short>
</element>

<element name="TFileStateCache">
<short>
Implements a state caching mechanism for files and directories.
</short>
<descr>
<p>
<var>TFileStateCache</var> is a class which implements a state caching
mechanism for files and directories. TFileStateCache uses an internal AVL
tree to store <var>TFileStateCacheItem</var> instances for the items in
the state caching mechanism. The tree stores values sorted in file name
(or path) order.
</p>
<p>
The <var>TimeStamp</var> property contains a counter value, assigned in the
constructor, which is maintained when items are added or updated in cache
storage. The value is assigned to cached items, and provides an indication
when the cached item may be out-of-date in the cache.
</p>
<p>
TFileStateCache provides methods to add and update items in the cache, and to
access and verify state flags for the TFileStateCacheItem instances.
</p>
</descr>
<seealso>
<link id="TFileStateCacheItem"/>
<link id="TFileStateCacheItemFlags"/>
<link id="TFileStateCacheItemFlag"/>
</seealso>
</element>

<!-- private -->
<element name="TFileStateCache.FFiles"/>
<element name="TFileStateCache.FTimeStamp"/>
<element name="TFileStateCache.FLockCount"/>
<element name="TFileStateCache.FChangeTimeStampHandler"/>

<element name="TFileStateCache.SetFlag">
<short>Includes or excludes a value in the Flags property.</short>
</element>
<element name="TFileStateCache.SetFlag.AFile">
<short>File or directory name for the cached item.</short>
</element>
<element name="TFileStateCache.SetFlag.AFlag">
<short>Identifies the Flag affected in the method.</short>
</element>
<element name="TFileStateCache.SetFlag.NewValue">
<short>
<b>True</b> to include the flag, <b>False</b> to exclude it.
</short>
</element>

<!-- public -->
<element name="TFileStateCache.Create">
<short>Constructor for the class instance.</short>
<descr>
<p>
<var>Create</var> is the constructor for the class instance. It allocates
resources needed for the internal AVL tree used to store the file or directory
items in the cache mechanism. The address for the 
<var>CompareFileStateItems</var>
routine is used to compare and sort the items added to the AVL tree. It also
sets the initial value in the <var>Timestamp</var> property.
</p>
</descr>
<seealso>
<link id="TFileStateCache.TimeStamp"/>
<link id="CompareFileStateItems"/>
</seealso>
</element>

<element name="TFileStateCache.Destroy">
<short>Destructor for the class instance.</short>
<descr>
<p>
<var>Destroy</var> is the overridden destructor for the class instance. It
frees resources allocated in and for the internal AVL tree used to store
cached file or directories. It also frees any change handler routines assigned
by calling the <var>AddChangeTimeStampHandler</var> method.
</p>
<p>
Destroy calls the inherited method prior to exit.
</p>
</descr>
<seealso>
<link id="TFileStateCache.AddChangeTimeStampHandler"/>
</seealso>
</element>

<element name="TFileStateCache.Lock">
<short>Increments the lock count for the caching mechanism.</short>
<descr/>
<seealso>
<link id="TFileStateCache.Unlock"/>
<link id="TFileStateCache.Locked"/>
</seealso>
</element>

<element name="TFileStateCache.Unlock">
<short>Decrements the lock count for the caching mechanism.</short>
<descr>
<p>
Raises an <var>Exception</var> if the lock count is 0 (or less) when the
method is called.
</p>
</descr>
<seealso>
<link id="TFileStateCache.Lock"/>
<link id="TFileStateCache.Locked"/>
</seealso>
</element>

<element name="TFileStateCache.Locked">
<short>
Indicates Lock has been called without a corresponding Unlock call.
</short>
<descr>
The return value is <b>True</b> when the internal lock count has a positive
non-zero value.
</descr>
<seealso>
<link id="TFileStateCache.Lock"/>
<link id="TFileStateCache.Unlock"/>
</seealso>
</element>
<element name="TFileStateCache.Locked.Result">
<short>
<b>True</b> when the internal lock count has a positive non-zero value.
</short>
</element>

<element name="TFileStateCache.IncreaseTimeStamp">
<short>
Increments the change counter or updates an item in the state cache.
</short>
<descr>
<p>
<var>AFileName</var> contains the file or directory name to update in the
storage for the cache.
</p>
<p>
When AFileName is an empty string (<b>''</b>), the entire cache is invalidated
by incrementing the change counter in the <var>TimeStamp</var> property.
If a value is provided in AFileName, a single item is invalidated in the cache
storage. The <var>FindFile</var> method is called to retrieve the
<var>TFileStateCacheItem</var> entry and to reset the values in its
<var>TestedFlags</var> property.
</p>
<p>
IncreaseTimeStamp signals each of the assigned change handlers for the
class instance using the value in AFileName as an argument.
</p>
</descr>
<seealso>
<link id="TFileStateCache.FindFile"/>
<link id="TFileStateCache.TimeStamp"/>
<link id="TFileStateCacheItem.Filename"/>
<link id="TFileStateCacheItem.PhysicalFilename"/>
<link id="TFileStateCacheItem.TestedFlags"/>
</seealso>
</element>
<element name="TFileStateCache.IncreaseTimeStamp.AFilename">
<short>
Name for the file or directory invalidated in the cache, or an empty string
to invalidate all cached items.
</short>
</element>

<element name="TFileStateCache.FileExistsCached">
<short>
Ensures that a cached item has an up-to-date "file exists" flag value.
</short>
<descr>
<p>
<var>FileExistsCached</var> ensures that a cached item with the name in
<var>AFileName</var> has an up-to-date "file exists" flag value in the cache.
</p>
<p>
Calls <var>Check</var> to use the valid flag value for an existing
<var>TFileStateCacheItem</var> instance in the cache. If the return value from
Check is <b>True</b>, no additional actions are performed in the method.
</p>
<p>
Otherwise, the flag value was not present for the specified cache item. The
<var>FileExistsUTF8</var> routine is called to determine if the file exists on
the local file system. <var>SetFlag</var> is called to update the
<var>fsciExists</var> flag for the cache item with the given name.
</p>
</descr>
<seealso>
<link id="TFileStateCache.Check"/>
<link id="TFileStateCacheItem.Filename"/>
<link id="TFileStateCacheItem.Flags"/>
</seealso>
</element>
<element name="TFileStateCache.FileExistsCached.Result">
<short>
<b>True</b> if the file exists on the local file system and in the cache.
</short>
</element>
<element name="TFileStateCache.FileExistsCached.AFilename">
<short>Name for the file to examine in the method.</short>
</element>

<element name="TFileStateCache.DirPathExistsCached">
<short>
Ensures that a cached item has an up-to-date "directory path exists" flag 
value.
</short>
<descr>
<p>
<var>DirPathExistsCached</var> ensures that a cached item with the name in
<var>AFileName</var> has an up-to-date "directory path exists" flag value in
the cache.
</p>
<p>
Calls <var>Check</var> to use the valid flag value for an existing
<var>TFileStateCacheItem</var> instance in the cache. If the return value from
Check is <b>True</b>, no additional actions are performed in the method.
</p>
<p>
Otherwise, the flag value was not present for the specified cache item. The
<var>DirPathExists</var> routine is called to determine if the file exists on
the local file system. <var>SetFlag</var> is called to update the
<var>fsciDirectory</var> flag for the cache item with the given name.
</p>
</descr>
<seealso>
<link id="TFileStateCache.Check"/>
<link id="TFileStateCacheItem.Filename"/>
<link id="TFileStateCacheItem.PhysicalFilename"/>
<link id="TFileStateCacheItem.Flags"/>
</seealso>
</element>
<element name="TFileStateCache.DirPathExistsCached.Result">
<short>
<b>True</b> if the directory exists on the local file system and in the cache.
</short>
</element>
<element name="TFileStateCache.DirPathExistsCached.AFilename">
<short>Name of the directory to examine in the method.</short>
</element>

<element name="TFileStateCache.DirectoryIsWritableCached">
<short>
Ensures that a cached item has an up-to-date "Directory is Writable" flag.
</short>
<descr>
<p>
<var>DirectoryIsWritableCached</var> ensures that the specified directory
has an up-to-date value for its "Directory is Writable" flag in the cache. It
calls <var>Check</var> to use a valid flag value for an existing
<var>TFileStateCacheItem</var> instance in the cache. If the return value from
Check is <b>True</b>, no additional actions are performed in the method.
</p>
<p>
Otherwise, the flag value was not present for the specified cache item. The
<var>DirectoryIsWritable</var> routine is called to determine if the directory
allows new entries to be created in the path. <var>SetFlag</var> is called to
update the <var>fsciDirectoryWritable</var> flag for the cache item with the
given name.
</p>
</descr>
<seealso>
<link id="TFileStateCache.Check"/>
<link id="TFileStateCacheItem.Filename"/>
<link id="TFileStateCacheItem.PhysicalFilename"/>
<link id="TFileStateCacheItem.Flags"/>
</seealso>
</element>
<element name="TFileStateCache.DirectoryIsWritableCached.Result">
<short>
<b>True</b> if the specified directory is writable in the local file system
and in the cache.
</short>
</element>
<element name="TFileStateCache.DirectoryIsWritableCached.DirectoryName">
<short>Name of the directory to examine in the method.</short>
</element>

<element name="TFileStateCache.FileIsExecutableCached">
<short>
Ensures that the "File is Executable" flag is up-to-date for a cache item.
</short>
<descr>
<p>
<var>FileIsExecutableCached</var> ensures that the cache item for the 
specified
file has an up-to-date value in its "File is Executable" flag. It calls
<var>Check</var> to get the cache item with the given name, and to examine its
flag values. If Check returns <b>True</b> for the flag, no additional actions
are performed in the method.
</p>
<p>
Otherwise, the <var>FileIsExecutable</var> routine is called to get the return
value. <var>SetFlag</var> is called to apply the <var>fsciExecutable</var> 
flag
value to the cached item.
</p>
</descr>
<seealso>
<link id="TFileStateCache.Check"/>
<link id="TFileStateCacheItem.Filename"/>
<link id="TFileStateCacheItem.PhysicalFilename"/>
<link id="TFileStateCacheItem.Flags"/>
<link id="#lazutils.lazfileutils.FileIsExecutable">FileIsExecutable</link>
</seealso>
</element>
<element name="TFileStateCache.FileIsExecutableCached.Result">
<short>
<b>True</b> if the specified file is an executable binary.
</short>
</element>
<element name="TFileStateCache.FileIsExecutableCached.AFilename">
<short>
Name for the file examined in the method.
</short>
</element>

<element name="TFileStateCache.FileIsReadableCached">
<short>
Ensures that the "File is Readable" flag is up-to-date for a cache item.
</short>
<descr/>
<seealso/>
</element>
<element name="TFileStateCache.FileIsReadableCached.Result">
<short><b>True</b> if the specified file is not read-only.</short>
</element>
<element name="TFileStateCache.FileIsReadableCached.AFilename">
<short>Name for the file examined in the method.</short>
</element>

<element name="TFileStateCache.FileIsWritableCached">
<short>
Ensures that the "File is Writable" flag is up-to-date for a cache item.
</short>
<descr/>
<seealso/>
</element>
<element name="TFileStateCache.FileIsWritableCached.Result">
<short>
<b>True</b> if the file is writable.
</short>
</element>
<element name="TFileStateCache.FileIsWritableCached.AFilename">
<short>
Name for the file examined in the method.
</short>
</element>

<element name="TFileStateCache.FileIsTextCached">
<short>
Ensures that the "File is Text" flag is up-to-date for a cache item.
</short>
<descr/>
<seealso/>
</element>
<element name="TFileStateCache.FileIsTextCached.Result">
<short>
<b>True</b> if the file is a text file (not a binary executable).
</short>
</element>
<element name="TFileStateCache.FileIsTextCached.AFilename">
<short>
Name for the file examined in the method.
</short>
</element>

<element name="TFileStateCache.FileAgeCached">
<short>
Ensures that the file age is up-to-date for a cache item.
</short>
<descr>
<p>
<var>FileAgeCached</var> differs from the related methods in the class 
instance. It returns a <var>LongInt</var> value instead of a 
<var>Boolean</var>, and contains the value from the <var>FileAge</var> routine 
in the RTL <file>SysUtils</file> unit. The value represents the last date that 
the file was modified, and the integer value does not include any time-related 
information for the modification timestamp.
</p>
<p>
FileAgeCached cannot be used for directory names; the value is always 
<b>-1</b> when used for a directory name.
</p>
<p>
FileAge is not related to the <var>TimeStamp</var> property for the cache.
</p>
</descr>
<seealso>
<link id="#rtl.sysutils.FileAge">FileAge</link>
</seealso>
</element>
<element name="TFileStateCache.FileAgeCached.Result">
<short>File age (last modification date) for the file.</short>
</element>
<element name="TFileStateCache.FileAgeCached.AFileName">
<short>Name for the file examined in the method.</short>
</element>

<element name="TFileStateCache.GetPhysicalFilenameCached">
<short>
Resolves the specified file name to a physical file on the local file system.
</short>
<descr>
<p>
The implementation is platform-specific. On the Windows platform, the value in 
<var>AFileName</var> is used as the return value. On UNIX-like platforms, which 
can have symbol links, the file name must be resolved to the physical file on 
the local file system. The cache is recursively searched to resolve a file name 
which resides on a symbolic link.
</p>
<p>
The return value contains the resolve path and file name, or an empty string if 
the file name cannot be resolved. When EmptyOnError is enabled, the value in 
the AFileName is returned - even when not resolved.
</p>
</descr>
<seealso/>
</element>
<element name="TFileStateCache.GetPhysicalFilenameCached.Result">
<short>
Path amd file name for a file name on symbolic links.
</short>
</element>
<element name="TFileStateCache.GetPhysicalFilenameCached.AFileName">
<short>
File name resolved in the method.
</short>
</element>
<element name="TFileStateCache.GetPhysicalFilenameCached.EmptyOnError">
<short>
<b>True</b> if an unresolved is empty when an error occurs. <b>False</b> if the 
value in AFileName is used when an error occurs.
</short>
</element>

<element name="TFileStateCache.FindFile">
<short>Gets (or creates) the cached item with the specified name.</short>
<descr>
<p>
<var>FindFile</var> is a <var>TFileStateCacheItem</var> function used to get,
or optionally create, a cache entry for the file or directory in
<var>Filename</var>.
</p>
<p>
FindFile resolves a relative path used in Filename by calling the
<var>ResolveDots</var> routine. The normalized name is used to get the
TFileStateCacheItem instance in the cache used as the return value for the
method.
</p>
<p>
If Filename was not found in the cache, and <var>CreateIfNotExists</var> is
set to <b>True</b>, a TFileStateCacheItem instance is created with the
<var>Timestamp</var> for the cache and added to the internal storage. An
<var>Exception</var> is raised if the cache item could not be added
(and retrieved) using the internal AVL tree storage.
</p>
<p>
If Filename was not found in the cache, and CreateIfNotExists is set to
<b>False</b>, the return value is <b>Nil</b>.
</p>
<p>
FindFile is used to implement the <var>Check</var> and
<var>IncreaseTimeStamp</var> methods.
</p>
</descr>
<seealso>
<link id="TFileStateCache.TimeStamp"/>
<link id="TFileStateCache.Check"/>
<link id="TFileStateCache.IncreaseTimeStamp"/>
<link id="TFileStateCacheItem"/>
</seealso>
</element>
<element name="TFileStateCache.FindFile.Result">
<short>Cached item with the specified name, or Nil.</short>
</element>
<element name="TFileStateCache.FindFile.Filename">
<short>Name for the file or directory to locate in the cache.</short>
</element>
<element name="TFileStateCache.FindFile.CreateIfNotExists">
<short><b>True</b> to create a cache item if it does not already exist.</short>
</element>

<element name="TFileStateCache.Check">
<short>
Checks the specified cache item to get a specific flag value.
</short>
<descr>
<p>
<var>Check</var> is a <var>Boolean</var> function used to check a flag value
in a cache item with the name in <var>Filename</var>.
</p>
<p>
<var>AFlag</var> identifies the flag value checked for the cache item.
</p>
<p>
<var>AFile</var> contains the cache item used to get the value for the
specified flag. The <var>FindFile</var> method is called to get (or create) a
cache item for the specified file or directory name. AFile is an output
parameter, and is used to return the <var>TFileStateCacheItem</var> instance 
to
the caller.
</p>
<p>
Check ensures that the cache item is valid (recent) using the
<var>Timestamp</var> for the class instance. When TimeStamp is more recent 
than
the value in the cache item, the cache item is updated with the current
Timestamp and its tested flags are cleared.
</p>
<p>
<var>FlagIsSet</var> is a variable parameter which contains the state for the
specific flag. <b>True</b> indicates the flag is set for the cache item.
<b>False</b> indicates that the flag was not already set in the cache item, or
has not been tested after resetting the Timestamp for an invalid cache item.
</p>
<p>
The return value is <b>True</b> when the flag in AFlag is one of the tested
flags in an existing cache item. It is <b>False</b> if the flag value has not
been accessed in the cache item, or when the Timestamp for an invalid cache
item was reset.
</p>
<p>
Check is used to implement methods which get or set specific flag values,
including:
</p>
<ul>
<li>FileExistsCached</li>
<li>DirPathExistsCached</li>
<li>DirectoryIsWritableCached</li>
<li>FileIsExecutableCached</li>
<li>FileIsReadableCached</li>
<li>FileIsWritableCached</li>
<li>FileIsTextCached</li>
<li>FileAgeCached</li>
<li>GetPhysicalFilenameCached</li>
</ul>
</descr>
<seealso>
<link id="TFileStateCache.FindFile"/>
<link id="TFileStateCache.TimeStamp"/>
<link id="TFileStateCache.FileExistsCached"/>
<link id="TFileStateCache.DirPathExistsCached"/>
<link id="TFileStateCache.DirectoryIsWritableCached"/>
<link id="TFileStateCache.FileIsExecutableCached"/>
<link id="TFileStateCache.FileIsReadableCached"/>
<link id="TFileStateCache.FileIsWritableCached"/>
<link id="TFileStateCache.FileIsTextCached"/>
<link id="TFileStateCache.FileAgeCached"/>
<link id="TFileStateCache.GetPhysicalFilenameCached"/>
<link id="TFileStateCacheItem.TimeStamp"/>
<link id="TFileStateCacheItem.Flags"/>
<link id="TFileStateCacheItem.TestedFlags"/>
</seealso>
</element>
<element name="TFileStateCache.Check.Result">
<short><b>True</b> if the flag is has been tested and set for the cache item.</short>
</element>
<element name="TFileStateCache.Check.Filename">
<short>File or directory to locate in the cache.</short>
</element>
<element name="TFileStateCache.Check.AFlag">
<short>Flag to examine for the cache item.</short>
</element>
<element name="TFileStateCache.Check.AFile">
<short>The cache item examined in the method.</short>
</element>
<element name="TFileStateCache.Check.FlagIsSet">
<short><b>True</b> if the flag was tested and set for the cache item.</short>
</element>

<element name="TFileStateCache.AddChangeTimeStampHandler">
<short>
Adds the specified handler routine to the class instance.
</short>
<descr/>
<seealso/>
</element>
<element name="TFileStateCache.AddChangeTimeStampHandler.Handler">
<short>Handler routine added in the method.</short>
</element>

<element name="TFileStateCache.RemoveChangeTimeStampHandler">
<short>
Removes the specified handler routine in the class instance.
</short>
<descr/>
<seealso/>
</element>
<element name="TFileStateCache.RemoveChangeTimeStampHandler.Handler">
<short>Handler routine removed in the method.</short>
</element>

<element name="TFileStateCache.CalcMemSize">
<short>
Gets the memory size needed for the class instance and its data.
</short>
<descr>
<p>
<var>CalcMemSize</var> is a <var>name</var> function used to get the amount of
memory needed for the class instance, including data stored in its properties.
The return value is a sum of the <var>InstanceSize</var> and the lengths for
the String values in <var>FileName</var> and <var>PhysicalFilename</var>.
</p>
</descr>
<seealso>
<link id="TFileStateCacheItem.Filename"/>
<link id="TFileStateCacheItem.PhysicalFilename"/>
<link id="#rtl.system.TObject.InstanceSize">TObject.InstanceSize</link>
</seealso>
</element>
<element name="TFileStateCache.CalcMemSize.Result">
<short>Memory size needed to store the class instance and its data.</short>
</element>

<element name="TFileStateCache.TimeStamp">
<short>
Timestamp (or revision) value for the cache storage.
</short>
<descr/>
<seealso>
<link id="TFileStateCacheItem.TimeStamp"/>
</seealso>
</element>

<element name="FileStateCache">
<short>
Unit global variable with the class instance for the state caching mechanism.
</short>
<descr>
<p>
<var>FileStateCache</var> is a <var>FileStateCache</var> variable which 
contains
the class instance used for the state caching mechanism. The default value for
the variable is Nil (unassigned).
</p>
</descr>
<seealso>
<link id="TFileStateCache"/>
</seealso>
</element>

<element name="FileExistsCached">
<short>
Gets the File Exists flag value for the specified file name.
</short>
<descr/>
<seealso/>
</element>
<element name="FileExistsCached.Result">
<short><b>True</b> if the file exists on the local file system.</short>
</element>
<element name="FileExistsCached.AFilename">
<short>File name examined in the routine.</short>
</element>

<element name="DirPathExistsCached">
<short>
Gets the Path Exists flag value for the specified directory path.
</short>
<descr/>
<seealso/>
</element>
<element name="DirPathExistsCached.Result">
<short><b>True</b> if the path exists on the local file system.</short>
</element>
<element name="DirPathExistsCached.AFilename">
<short>Path to the directory examined in the routine.</short>
</element>

<element name="DirectoryIsWritableCached">
<short>
Gets the Directory is Writable flag value for the specified path.
</short>
<descr/>
<seealso/>
</element>
<element name="DirectoryIsWritableCached.Result">
<short>
<b>True</b> if the specified directory allows files or sub-directories to be created.
</short>
</element>
<element name="DirectoryIsWritableCached.ADirectoryName">
<short>Path examined in the routine.</short>
</element>

<element name="FileIsExecutableCached">
<short>
Gets the File is Executable flag value for the specified file name.
</short>
<descr/>
<seealso/>
</element>
<element name="FileIsExecutableCached.Result">
<short>
<b>True</b> if the specified file is an executable (binary) file.
</short>
</element>
<element name="FileIsExecutableCached.AFilename">
<short>
Name for the file examined in the routine.
</short>
</element>

<element name="FileIsReadableCached">
<short>
Gets the File is Readable flag value for the specified file name.
</short>
<descr/>
<seealso/>
</element>
<element name="FileIsReadableCached.Result">
<short>
<b>True</b> if the specified file is readable.
</short>
</element>
<element name="FileIsReadableCached.AFilename">
<short>
Name for the file examined in the routine.
</short>
</element>

<element name="FileIsWritableCached">
<short>
Gets the File is Writable flag value for the specified file name.
</short>
<descr/>
<seealso/>
</element>
<element name="FileIsWritableCached.Result">
<short>
<b>True</b> if the specified file is writable (not read-only).
</short>
</element>
<element name="FileIsWritableCached.AFilename">
<short>
Name for the file examined in the routine.
</short>
</element>

<element name="FileIsTextCached">
<short>
Gets the File is Text flag for the specified file name.
</short>
<descr/>
<seealso/>
</element>
<element name="FileIsTextCached.Result">
<short>
<b>True</b> if the specified file is a text (not a binary executable) file.
</short>
</element>
<element name="FileIsTextCached.AFilename">
<short>
Name for the file examined in the routine.
</short>
</element>

<element name="FileAgeCached">
<short>
Gets the file age for the specified file or directory.
</short>
<descr/>
<seealso/>
</element>
<element name="FileAgeCached.Result">
<short>File age for the specified file or directory.</short>
</element>
<element name="FileAgeCached.AFileName">
<short>File or directory name examined in the routine.</short>
</element>

<element name="GetPhysicalFilenameCached">
<short>
Gets the physical file name for the specified file or directory name.
</short>
<descr>
<p>
<var>GetPhysicalFilenameCached</var> is a <var>String</var> function used to
get the physical file name for the value specified in <var>AFileName</var>.
The return value contains the actual file name for a symbolic link or 
reference
on the local file system.
</p>
<p>
<var>EmptyOnError</var> indicates that the return value can be an empty string
(<b>''</b>) if AFilename cannot be resolved. When set to <b>False</b>, the
original file in AFileName is used as the return value.
</p>
<p>
GetPhysicalFilenameCached provides two (2) ways to resolve the value in
AFilename:
</p>
<ul>
<li>
Calling the GetPhysicalFilenameCached method in the FileStateCache
singleton (when assigned). This is the default code path in the routine.
</li>
<li>
Calling the GetPhysicalFilename routine.
</li>
</ul>
</descr>
<seealso>
<link id="TFileStateCache.GetPhysicalFilenameCached"/>
<link id="GetPhysicalFilename"/>
<link id="FileStateCache"/>
</seealso>
</element>
<element name="GetPhysicalFilenameCached.Result">
<short>Actual file name for the symbolic link or reference.</short>
</element>
<element name="GetPhysicalFilenameCached.AFilename">
<short>File name resolved in the routine.</short>
</element>
<element name="GetPhysicalFilenameCached.EmptyOnError">
<short><b>True</b> to return an empty string if AFilename is not found.</short>
</element>

<element name="InvalidateFileStateCache">
<short>
Invalidates one or more items in the state cache.
</short>
<descr>
<p>
Calls the <var>IncreaseTimeStamp</var> method in <var>FileStateCache</var>
using the value in <var>FileName</var> as the target. When FileName exists
in the cache, it is the only item affected in the method. If FileName is an
empty string (<b>''</b>), all items in the cache are invalidated.
</p>
</descr>
<seealso>
<link id="FileStateCache"/>
<link id="TFileStateCache.IncreaseTimeStamp"/>
<link id="TFileStateCache.TimeStamp"/>
<link id="TFileStateCacheItem.TimeStamp"/>
</seealso>
</element>

<element name="InvalidateFileStateCache.Filename">
<short>Name for the file or directory invalidated in the cache.</short>
</element>

<element name="CompareFileStateItems">
<short>
Gets the relative order for the file names in the specified TFileStateCacheItem 
entries.
</short>
<descr>
<p>
Used as the sort/compare routine for the TAVLTree instance in TFileStateCache.
</p>
</descr>
<seealso>
<link id="TFileStateCacheItem"/>
<link id="#lazutils.lazfileutils.CompareFilenames">CompareFilenames</link>
</seealso>
</element>
<element name="CompareFileStateItems.Result">
<short>
Returns 0 if the UTF-8 file name have the same value. Returns -1 if the file 
name in Data1 comes before the file name in Data2. Returns 1 if the file name 
in Data1 comes after the file name in Data2.
</short>
</element>
<element name="CompareFileStateItems.Data1">
<short>
TFileStateCacheItem item with the file name compared in the routine.
</short>
</element>
<element name="CompareFileStateItems.Data2">
<short>
TFileStateCacheItem item with the file name compared in the routine.
</short>
</element>

<element name="CompareFilenameWithFileStateCacheItem">
<short>
Compares a value to a file name in a TFileStateCacheItem instance.
</short>
<descr/>
<seealso>
<link id="TFileStateCacheItem"/>
<link id="#lazutils.lazfileutils.CompareFilenames">CompareFilenames</link>
</seealso>
</element>
<element name="CompareFilenameWithFileStateCacheItem.Result">
<short>
Returns 0 if the UTF-8 file name have the same value. Returns -1 if the file 
name in Data1 comes before the file name in Data2. Returns 1 if the file name 
in Data1 comes after the file name in Data2.
</short>
</element>
<element name="CompareFilenameWithFileStateCacheItem.Key">
<short>
Pointer to the string value compared to the file name in the file state cache 
entry.
</short>
</element>
<element name="CompareFilenameWithFileStateCacheItem.Data">
<short>
Pointer to the TFileStateCacheItem instance with the file name compared in the 
routine.
</short>
</element>

<element name="LUInvalidChangeStamp">
<short>
Integer value used as the invalid timestamp value for the cache mechanism.
</short>
<descr/>
<seealso/>
</element>

<element name="LUInvalidChangeStamp64">
<short>
Int64 value used as the invalid timestamp value for the cache mechanism.
</short>
<descr/>
<seealso/>
</element>

<element name="LUIncreaseChangeStamp">
<short>Increments the specified Integer timestamp value.</short>
<descr/>
<seealso/>
</element>
<element name="LUIncreaseChangeStamp.ChangeStamp">
<short>Timestamp value modified in the routine.</short>
</element>

<element name="LUIncreaseChangeStamp64">
<short>Increments the specified Int64 timestamp value.</short>
<descr/>
<seealso/>
</element>
<element name="LUIncreaseChangeStamp64.ChangeStamp">
<short>Timestamp value modified in the routine.</short>
</element>

<element name="TOnFileExistsCached">
<short>
Specifies an event handler signalled to get the "file exists" flag for an item
in the cache.
</short>
<descr/>
<seealso/>
</element>
<element name="TOnFileExistsCached.Result">
<short><b>True</b> if the file exists on the local file system.</short>
</element>
<element name="TOnFileExistsCached.Filename">
<short>File name examined in the event handler.</short>
</element>

<element name="TOnFileAgeCached">
<short>
Specifies an event handler signalled to get the file age for an item in the 
cache.
</short>
<descr/>
<seealso/>
</element>
<element name="TOnFileAgeCached.Result">
<short>File age for the specified file or directory.</short>
</element>
<element name="TOnFileAgeCached.Filename">
<short>File or directory examined in the handler.</short>
</element>

<element name="OnFileExistsCached">
<short>
Event handler signalled to get the File Exists flag for the specified file 
name.
</short>
<descr/>
<seealso/>
</element>

<element name="OnFileAgeCached">
<short>
Event handler signalled to get the file age for the specified file name.
</short>
<descr>
<p>
<var>OnFileAgeCached</var> is a <var>TOnFileAgeCached</var> variable with the
unit global event handler used to get the file age for a given file name.
It is signalled from the <var>FileAgeCached</var> routine (when assigned), and
is used instead of calling the <var>TFileStateCache.FileAgeCached</var> method
or the <var>FileAgeUTF8</var> routine in <file>LazUtils</file>.
</p>
</descr>
<seealso>
<link id="TOnFileAgeCached"/>
<link id="FileAgeCached"/>
<link id="FileStateCache"/>
<link id="TFileStateCache.FileAgeCached"/>
<link id="#lazutils.lazfileutils.FileAgeUTF8">FileAgeUTF8</link>
</seealso>
</element>

</module>
<!-- LazFileCache -->
</package>
</fpdoc-descriptions>
