TMaskBase class

In unit Masks

Implements the base class used to define and evaluate a mask expression.

Declaration

pascal

TMaskBase = class

Descends from it: TMaskUTF8

Description

TMaskBase provides the framework or API used to examine and handle a mask expression. It provides member fields used to store the compiled op codes for the mask expression as well other state information. Methods are provides to raise exceptions for specific mask error conditions. Properties are also implemented to represent the case sensitivity, escape character, range handling, and op codes enabled for a mask expression.

Please note that TMaskBase does not capture, compile or store the mask expression. Those actions are performed in a descendent class.

Properties

`CaseSensitive`	public	Indicates if the mask expression is case sensitive.
`AutoReverseRange`	public	Indicates if a range expression is automatically reversed when the starting value is larger than the ending value.
`EscapeChar`	public	Contains the character used to escape the following character in a mask expression.
`MaskOpCodes`	public	Contains the set of mask op codes enabled for the class instance.

Methods

`Add`	protected	Adds one or more mask op codes found in the compiled mask expression.
`IncrementLastCounterBy`	protected	Moves the internal counter for a specified op code when processing a range expression.
`PrepareCompile`	protected	Resets values in internal members used in the implementation.
`Exception_InvalidCharMask`	protected	Raises an exception when the specified mask character or offset is invalid.
`Exception_MissingCloseChar`	protected	Raises an EMaskError exception when the closing ']' character is omitted from a set or range expression.
`Exception_IncompleteMask`	protected	Raises an EMaskError exception when escaped characters in a set is enabled, but range processing has not been enabled.
`Exception_InvalidEscapeChar`	protected	Raises an EMaskError exception when an invalid value is assigned to the EscapeChar property.
`Exception_InternalError`	protected	Raises an EMaskError exception when a parsed op code does not match an expected value in the mask expression.
`Create`	public	Constructor for the class instance.

Fields

`fCaseSensitive`	protected	Member with the case sensitivity settings for a mask expression.
`fAutoReverseRange`	protected	Member with the value for the AutoReverseRange property.
`fMaskIsCompiled`	protected	Member which indicates if the mask expression has been compiled.
`fMaskCompiled`	protected	Member which stores the op codes needed to evaluate the mask expression and compare specified values.
`fMaskCompiledIndex`	protected	Member with the current offset an op code for the compiled mask expression.
`fMaskCompiledAllocated`	protected	Member with the allocated storage for the compiled mask expression.
`fMaskCompiledLimit`	protected	Member with the ordinal position represented in cMaskCompiledIndex.
`fMaskLimit`	protected	Member with the last position in the mask expression where an op code can be applied.
`fMatchStringLimit`	protected	Member with the last position in a compared value that can used to match the mask expression.
`fMatchMinimumLiteralBytes`	protected	Member with the minimum number of bytes for a literal character (normally 1).
`fMatchMaximumLiteralBytes`	protected	Member with the maximum number of bytes for a literal character (normally 4 for UTF-8 codepoints).
`fMaskOpcodesAllowed`	protected	Member with the op code identifiers allowed for the mask expression.
`fMaskEscapeChar`	protected	Member with the escape character for the mask expression. An escape character forces the next mask character to be treated as a literal and not a wildcard.

Types and constants

`TMaskParsedCode`	protected	Represents op codes found when parsing / compiling a mask expression.
`TMaskFailCause`	protected	Represents success or failure conditions when handling mask characters.
`GROW_BY`	protected	Number bytes used to grow the storage for op codes in a compiled mask expression.
`DefaultSpecialChars`	protected

An experiment, built from Lazarus main 2dfa93c66e of 10-22-2026. Not the official Lazarus documentation.