Description:

This class implements an ALib Expression Compiler Plugin and thus enables "run-time expressions" to work with nodes of FTree

Unless multithreaded compilation of expressions is planned, an application should create one singleton of this class.

Method CreateFilter creates an object of inner type Filter, which implements the FFilter interface used with scan parameters of overloaded function ScanFiles. This allows run-time evaluation of filter rules, for example, rules coming from the command-line, from configuration files or from interactive end-user input (hence from an UX/UI).

Of course, the expression compiler can also be used directly without using the inner Filter class for evaluation, and expressions then do not need to return a boolean "yes/no" result.

See also: For a quick tutorial, see the Programmer's Manual.

Implemented Expression Features

Compiler plug-in that provides expressions on filesystem entries, stored in nodes of class FTree.

All identifier and function names are defined to be matched case-insensitive and can be abbreviated along their CamelHumps. This means an identifier called

CamelHumpCounter

can be abbreviated to:

CamelHC
CHCounter
CamHuCo
CHC
chc
cHc

and so on.

Furthermore, the matchable tokens are not hard-coded but resourced with ALib Camp singleton FILES. With that, for example, language translations might be performed.

Types:

This plug-in introduces the following types to the expression compiler:

Each type is auto-cast to built-in expression type Integer to allow all common operators, especially bitwise boolean operators.

Constants:

Type	Name	Min. Abbreviation	Description
Permissions	OwnerRead	ore	Used test result of function Permission.
Permissions	OwnerWrite	ow	Used test result of function Permission.
Permissions	OwnerExecute	oe	Used test result of function Permission.
Permissions	GroupRead	gr	Used test result of function Permission.
Permissions	GroupWrite	gw	Used test result of function Permission.
Permissions	GroupExecute	ge	Used test result of function Permission.
Permissions	OthersRead	otr	Used test result of function Permission.
Permissions	OthersWrite	otw	Used test result of function Permission.
Permissions	OthersExecute	ote	Used test result of function Permission.
Types	Directory	dir	Used to compare the result of function Type.
Types	SymbolicLinkDir	sld	Used to compare the result of function Type.
Types	Regular	reg	Used to compare the result of function Type.
Types	SymbolicLink	sl	Used to compare the result of function Type.
Types	Block	block	Used to compare the result of function Type.
Types	Character	character	Used to compare the result of function Type.
Types	Fifo	fifo	Used to compare the result of function Type.
Types	Socket	socket	Used to compare the result of function Type.

Constant Constructor Functions:

Return Type	Name	Min. Abbreviation	Signature	Description
Integer	KiloBytes	KB	int	Returns the given number multiplied with 2^10.
Integer	MegaBytes	MB	int	Returns the given number multiplied with 2^20.
Integer	GigaBytes	GB	int	Returns the given number multiplied with 2^30.
Integer	TeraBytes	TB	int	Returns the given number multiplied with 2^40.
Integer	PetaBytes	PB	int	Returns the given number multiplied with 2^50.
Integer	ExaBytes	EB	int	Returns the given number multiplied with 2^60.

Functions:

Return Type	Name	Min. Abbreviation	Signature	Description
String	Name	name	./.	Returns the file name.
Types	Type	ty	./.	Returns the result of Type.
Boolean	IsDirectory	isdir	./.	Returns the result of IsDirectory.
Boolean	IsSymbolicLink	issl	./.	Returns the result of IsSymbolicLink.
Integer	Size	size	./.	Returns the result of Size.
DateTime	Date	timestamp	./.	Returns the result of MDate.
DateTime	MDate	md	./.	Returns the result of MDate.
DateTime	BDate	bd	./.	Returns the result of BDate.
DateTime	CDate	cd	./.	Returns the result of CDate.
DateTime	ATime	ad	./.	Returns the result of ADate.
Permissions	Permissions	perm	./.	Returns the result of Permissions.
TOwnerAndGroupID	Owner	owner	./.	Returns the result of Owner.
TOwnerAndGroupID	Group	group	./.	Returns the result of Group.
TOwnerAndGroupID	UserID	uid	./.	Returns the current user's ID (calls posix getuid()).
TOwnerAndGroupID	GroupID	gid	./.	Returns the current user's group ID (calls posix getgid()).

Availability: This class is available only if the module ALib Expressions is included in the ALib Build.

Definition at line 121 of file fileexpressions.inl.

Inner Type Index:
struct	FexScope
class	Filter
struct	Plugin

Public Field Index:
Compiler	compiler
	The expression compiler.
Plugin	plugin
	The file expression Plugin.

Public Method Index:
	FileExpressions ()
	Default constructor.
SPFileFilter	CreateFilter (const String &expressionString)

Field Details:

◆ compiler

Compiler alib::files::FileExpressions::compiler

The expression compiler.

Definition at line 204 of file fileexpressions.inl.

◆ plugin

Plugin alib::files::FileExpressions::plugin

The file expression Plugin.

Definition at line 205 of file fileexpressions.inl.

Constructor(s) / Destructor Details:

◆ FileExpressions()

alib::files::FileExpressions::FileExpressions ( )

Default constructor.

Definition at line 234 of file fileexpressions.cpp.

Method Details:

◆ CreateFilter()

SPFileFilter alib::files::FileExpressions::CreateFilter ( const String & expressionString )

Creates a file filter using the expression compiler of this instance.

Parameters

expressionString The expression string to filter files and directories.

Returns: A shared pointer to the dynamically allocated filter object.

Definition at line 237 of file fileexpressions.cpp.

The documentation for this class was generated from the following files: