JCL Help:TJclRegEx.Compile@string@Boolean@Boolean@Boolean
JCL Help: TJclRegEx.Compile Method
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Summary
Converts a regular expression into the form required for the PCRE.DLL library.
Pascal
public function Compile(const Pattern: string; Study: Boolean; UserLocale: Boolean = False; JITCompile: Boolean = False): Boolean;
Parameters
| Parameters | Description |
| const Pattern: string | Regular expression to use when comparing a text subject using the regular expression engine. |
| Study: Boolean | Indicates if optimization is required for the regular expression. |
| UserLocale: Boolean = False | Indicates if non-standard localization is required for the regular expression. |
| JITCompile: Boolean = False | Enable the Just-In-Time compilation of this regular expression. |
Return Value
Boolean - True indicates successful completion of the method.
Exceptions
EPCREError - Exception raised when the regular expression in Pattern contains an empty string ().
Description
Compile is a method used to convert a regular expression into the form required for the PCRE.DLL library, and to optionally perform optimization and localization for the regular expression.
Pattern indicates the regular expression to be compiled. Pattern must contain a string that meets the syntax and semantics of the regular expressions supported by PCRE. The power of regular expressions comes from the ability to include alternatives and repetitions in the pattern. These are encoded in the pattern by the use of metacharacters, which do not stand for themselves but instead are interpreted in some special way.
There are two different sets of metacharacters: those that are recognized anywhere in the pattern except within square brackets, and those that are recognized in square brackets. Outside square brackets, the metacharacters are as follows:
| Metacharacter | Description |
| \ | general escape character with several uses |
| ^ | assert start of string (or line, in multiline mode) |
| $ | assert end of string (or line, in multiline mode) |
| . | match any character except newline (by default) |
| [ | start character class definition |
| start of alternative branch | |
| ( | start subpattern |
| ) | end subpattern |
| ? | extends the meaning of ( also 0 or 1 quantifier also quantifier minimizer |
| * | 0 or more quantifier |
| + | 1 or more quantifier also "possessive quantifier" |
| { | start min/max quantifier |
Part of a pattern that is in square brackets is called a "character class". In a character class the only metacharacters are:
| Metacharacter | Description |
| \ | general escape character |
| ^ | negate the class, but only if the first character |
| - | indicates character range |
| [ | POSIX character class (followed by POSIX syntax) |
| ] | terminates the character class |
Please refer to the documentation in PCRE Patterns for a more detailed description of regular expressions and metacharacters.
Study indicates if the regular expression should be inspected for additional information that can be extracted to speed up matching performance. Set Study to True if the same compiled regular expression will be used in multiple calls to the Match method.
UserLocale indicates that a non-standard locale is in use on the local machine, and show be used to override the character tables built into the PCRE library. Set UserLocale to True to force the users' locale to be used instead of the default encodings in the PCRE library.
Values in the Options property are used to configure the regular expression engine in the PCRE library, and to alter the run-time behavior of pattern matching. Set values in the Options property prior to calling Compile or Match to control the configuration and behavior of the PCRE library.
Refer to the documentation for TJclRegExOption for a description of the values used in the Options property.
The compiled regular expression representing Pattern is stored internally in TJclRegEx for subsequent use in the Match method. An EPCREError exception is raised if Pattern contains an empty string ().
Compile returns a Boolean value that indicates if the regular expression in Pattern is successfully compiled (and optionally optimized).
Use the ErrorMessage and ErrorOffset properties to determine the type and location of a syntax error detected in the Pattern argument.
Use the Match method to comapre a text subject using the compiled regular expression.
See Also
Options Match ErrorMessage ErrorOffset TJclRegExOption TJclRegExOptions EPCREError
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