Regex Class Reference

#include <Pt/Regex.h>

Regular Expressions for Unicode Strings. More...

Public Member Functions
	Regex ()
	Default Constructor.
	Regex (const Pt::Char *ex)
	Construct from regex string.
	Regex (const Pt::String &ex)
	Construct from regex string.
	Regex (const Regex &other)
	Copy constructor.
	~Regex ()
	Destructor.
Regex &	operator= (const Regex &other)
	Assignment operator.
bool	match (const Pt::String &str, RegexSMatch &sm) const
	Matches the regular experession to a string.
bool	match (const Pt::String &str) const
	Returns true if string matches.
bool	match (const Char *str, RegexSMatch &sm) const
	Matches the regular experession to a string.
bool	match (const Char *str) const
	Returns true if string matches.

Detailed Description

The Pt::Regex class allows to match a string pattern in unicode text. It resembles the std::basic_regex class and can be used to support systems, where std::basic_regex is not available in the standard C++ implementation. The syntax for the match pattern is similar to the extended POSIX syntax. The following table shows the special characters that can be used to write regular expressions:

.	Any character
[ ]	A character in a given set
[^ ]	A character not in a given set
^	Begin of line
$	End of line
\<	Begin of a word
\>	End of a word
( )	A marked subexpression
*	Matches the preceding element zero or more times
?	Matches the preceding element zero or one time
+	Matches the preceding element one or more times
|	Matches either the expression before or after the operator
\	Escapes the next character

The regular expression is constructed from a unicode string, either a Pt::String or a null-terminated sequence of unicode characters of type Pt::Char. It can then be used to match it against unicode strings as shown in the next example:

Pt::String expr = L"[hc]ats";
Pt::Regex regex(expr);
 
Pt::String str1 = L"I like cats!";
Pt::String str2 = L"I like hats!";
Pt::String str3 = L"I like bats!";
 
// this does match
bool matched = regex.match(str1);
 
// this does also match
matched = regex.match(str2);
 
// this does not match
matched = regex.match(str3);

It is also possibe to match a regular expression against a unicode input string and find out what tokens in the string actually matched. The match() member function has an overload, which fills a Pt::RegexSMatch with the result. Note that the first result at index 0 is always the input string itself. The following example illustrates this:

Pt::String expr = L"([0-9]+)\.([0-9]+)\.([0-9]+)\.([0-9]+)";
Pt::Regex regex(expr);
 
Pt::String str = L"My IP address is 192.168.0.77";
 
Pt::RegexSMatch smatch;
bool matched = regex.match(str, smatch);
if(matched)
{
    std::cout << "IP: " << smatch.str(1).narrow() << std::endl;
}
else
{
    std::cout << "No IP in " << smatch.str(0).narrow() << std::endl;
}

Member Function Documentation

match() [1/2]

bool match	(	const Pt::String &	str,
		RegexSMatch &	sm ) const

The result sm holds pointers into the original string that was matched and therefore should not be used after the original string was destroyed.

match() [2/2]

bool match	(	const Char *	str,
		RegexSMatch &	sm ) const

The result @ sm holds pointers into the original string that was matched and therefore should not be used after the original string was destroyed.