wxRegEx Class Reference

#include <wx/regex.h>

Detailed Description

wxRegEx represents a regular expression.

This class provides support for regular expressions matching and also replacement.

It is built on top of either the system library (if it has support for POSIX regular expressions - which is the case of the most modern Unices) or uses the built in Henry Spencer's library. Henry Spencer would appreciate being given credit in the documentation of software which uses his library, but that is not a requirement.

Regular expressions, as defined by POSIX, come in two flavours: extended and basic. The builtin library also adds a third flavour of expression advanced, which is not available when using the system library.

Unicode is fully supported only when using the builtin library. When using the system library in Unicode mode, the expressions and data are translated to the default 8-bit encoding before being passed to the library.

On platforms where a system library is available, the default is to use the builtin library for Unicode builds, and the system library otherwise. It is possible to use the other if preferred by selecting it when building the wxWidgets.

Library:  wxBase

Category:  Data Structures

Examples:

A bad example of processing some text containing email addresses (the example is bad because the real email addresses can have more complicated form than user@.nosp@m.host.nosp@m..net):

wxString text;
...
wxRegEx reEmail = "([^@]+)@([[:alnum:].-_].)+([[:alnum:]]+)";
if ( reEmail.Matches(text) )
{
    wxString text = reEmail.GetMatch(email);
    wxString username = reEmail.GetMatch(email, 1);
    if ( reEmail.GetMatch(email, 3) == "com" ) // .com TLD?
    {
        ...
    }
}

// or we could do this to hide the email address
size_t count = reEmail.ReplaceAll(text, "HIDDEN@\\2\\3");
printf("text now contains %u hidden addresses", count);

Public Member Functions
	wxRegEx ()
	Default constructor: use Compile() later.
	wxRegEx (const wxString &expr, int flags=wxRE_DEFAULT)
	Create and compile the regular expression, use IsValid() to test for compilation errors.
	~wxRegEx ()
	Destructor.
bool	Compile (const wxString &pattern, int flags=wxRE_DEFAULT)
	Compile the string into regular expression, return true if ok or false if string has a syntax error.
bool	GetMatch (size_t *start, size_t *len, size_t index=0) const
	Get the start index and the length of the match of the expression (if index is 0) or a bracketed subexpression (index different from 0).
wxString	GetMatch (const wxString &text, size_t index=0) const
	Returns the part of string corresponding to the match where index is interpreted as above.
size_t	GetMatchCount () const
	Returns the size of the array of matches, i.e. the number of bracketed subexpressions plus one for the expression itself, or 0 on error.
bool	IsValid () const
	Return true if this is a valid compiled regular expression, false otherwise.
bool	Matches (const wxString &text, int flags=0) const
	Matches the precompiled regular expression against the string text, returns true if matches and false otherwise.
int	Replace (wxString *text, const wxString &replacement, size_t maxMatches=0) const
	Replaces the current regular expression in the string pointed to by text, with the text in replacement and return number of matches replaced (maybe 0 if none found) or -1 on error.
int	ReplaceAll (wxString *text, const wxString &replacement) const
	Replace all occurrences: this is actually a synonym for Replace().
int	ReplaceFirst (wxString *text, const wxString &replacement) const
	Replace the first occurrence.
bool	Matches (const wxChar *text, int flags=0) const
	Matches the precompiled regular expression against the string text, returns true if matches and false otherwise.
bool	Matches (const wxChar *text, int flags, size_t len) const
	Matches the precompiled regular expression against the string text, returns true if matches and false otherwise.

Constructor & Destructor Documentation

wxRegEx::wxRegEx

(

)

Default constructor: use Compile() later.

wxRegEx::wxRegEx	(	const wxString &	expr,
		int	flags = wxRE_DEFAULT
	)

Create and compile the regular expression, use IsValid() to test for compilation errors.

As for the flags, please see wxRE_FLAGS.

wxRegEx::~wxRegEx

(

)

Destructor.

It's not virtual, don't derive from this class.

Member Function Documentation

bool wxRegEx::Compile	(	const wxString &	pattern,
		int	flags = wxRE_DEFAULT
	)

Compile the string into regular expression, return true if ok or false if string has a syntax error.

As for the flags, please see wxRE_FLAGS.

bool wxRegEx::GetMatch	(	size_t *	start,
		size_t *	len,
		size_t	index = 0
	)		const

Get the start index and the length of the match of the expression (if index is 0) or a bracketed subexpression (index different from 0).

May only be called after successful call to Matches() and only if wxRE_NOSUB was not used in Compile().

Returns false if no match or if an error occurred.

wxString wxRegEx::GetMatch	(	const wxString &	text,
		size_t	index = 0
	)		const

Returns the part of string corresponding to the match where index is interpreted as above.

Empty string is returned if match failed.

May only be called after successful call to Matches() and only if wxRE_NOSUB was not used in Compile().

size_t wxRegEx::GetMatchCount

(

)

const

Returns the size of the array of matches, i.e. the number of bracketed subexpressions plus one for the expression itself, or 0 on error.

May only be called after successful call to Compile(). and only if wxRE_NOSUB was not used.

bool wxRegEx::IsValid

(

)

const

Return true if this is a valid compiled regular expression, false otherwise.

bool wxRegEx::Matches	(	const wxChar *	text,
		int	flags = 0
	)		const

Matches the precompiled regular expression against the string text, returns true if matches and false otherwise.

Flags may be combination of wxRE_NOTBOL and wxRE_NOTEOL, see wxRE_NOT_FLAGS.

Some regex libraries assume that the text given is null terminated, while others require the length be given as a separate parameter. Therefore for maximum portability assume that text cannot contain embedded nulls.

When the Matches(const wxChar *text, int flags = 0) form is used, a wxStrlen() will be done internally if the regex library requires the length. When using Matches() in a loop the Matches(text, flags, len) form can be used instead, making it possible to avoid a wxStrlen() inside the loop.

May only be called after successful call to Compile().

bool wxRegEx::Matches	(	const wxChar *	text,
		int	flags,
		size_t	len
	)		const

Matches the precompiled regular expression against the string text, returns true if matches and false otherwise.

Flags may be combination of wxRE_NOTBOL and wxRE_NOTEOL, see wxRE_NOT_FLAGS.

Some regex libraries assume that the text given is null terminated, while others require the length be given as a separate parameter. Therefore for maximum portability assume that text cannot contain embedded nulls.

When the Matches(const wxChar *text, int flags = 0) form is used, a wxStrlen() will be done internally if the regex library requires the length. When using Matches() in a loop the Matches(text, flags, len) form can be used instead, making it possible to avoid a wxStrlen() inside the loop.

May only be called after successful call to Compile().

bool wxRegEx::Matches	(	const wxString &	text,
		int	flags = 0
	)		const

Matches the precompiled regular expression against the string text, returns true if matches and false otherwise.

Flags may be combination of wxRE_NOTBOL and wxRE_NOTEOL, see wxRE_NOT_FLAGS.

May only be called after successful call to Compile().

int wxRegEx::Replace	(	wxString *	text,
		const wxString &	replacement,
		size_t	maxMatches = 0
	)		const

Replaces the current regular expression in the string pointed to by text, with the text in replacement and return number of matches replaced (maybe 0 if none found) or -1 on error.

The replacement text may contain back references \number which will be replaced with the value of the corresponding subexpression in the pattern match. \0 corresponds to the entire match and & is a synonym for it. Backslash may be used to quote itself or & character.

maxMatches may be used to limit the number of replacements made, setting it to 1, for example, will only replace first occurrence (if any) of the pattern in the text while default value of 0 means replace all.

int wxRegEx::ReplaceAll	(	wxString *	text,
		const wxString &	replacement
	)		const

Replace all occurrences: this is actually a synonym for Replace().

See Also

ReplaceFirst()

int wxRegEx::ReplaceFirst	(	wxString *	text,
		const wxString &	replacement
	)		const

Replace the first occurrence.