Working with regular expression

Regex utility

Fano Framework provides regex utility through IRegex interface.

IRegex = interface
    ['{E08AD12B-C606-48FF-A9FA-728EAB14AB35}']
    function replace(
        const regexPattern : string;
        const source : string;
        const replacement : string
    ) : string;

    function quote(const regexPattern : string) : string;

    function match(
        const regexPattern : string;
        const source : string
    ) : TRegexMatchResult;

    function greedyMatch(
        const regexPattern : string;
        const source : string
    ) : TRegexMatchResult;

end;

Built-in IRegex implementation

Currently, Fano Framework provides TRegex class that implements IRegex interface which is a thin wrapper for Free Pascal built-in regex library (TRegExpr).

To create different IRegex implementation, just create new class that implement this interface.

Match string against regex pattern

To match string against regex pattern, you use match() or greedyMatch() method. Former method stops as soon as it finds a match while latter try to match as many as possible.

They accept same parameters:

regexPattern contains regular expression pattern to match.
source contains actual string to match.

They return TRegexMatchResult which is a record declared like so

TRegexMatches = array of array of string;
TRegexMatchResult = record
    matched : boolean;
    matches : TRegexMatches;
end;

matched field tells if there is a match and matched strings are in matches field which is empty array when matchedis false.

var
    regex : IRegex;
    matches : TRegexMatchResult;
...
regex := TRegex.create();
matches := regex.match('\[\[\s*([a-zA-Z0-9]*)\s*\]\]', 'This is [[ myVar ]]');

Above code matches string inside [[ ... ]] and will yield

matches.matched = true
matches.matches[0][0] = '[[ myVar ]]'
matches.matches[0][1] = 'myVar'

Replace string with regex pattern.

To replace string call replace() method. It accepts three parameters,

regexPattern contains regex pattern to match.
source is input string
replacement is replacement

When it finds match, replacement wil replace matched string.

var
    regex : IRegex;
    newStr : string;
...
regex := TRegex.create();
newStr := regex.match('\[\[\s*([a-zA-Z0-9]*)\s*\]\]', 'This is [[ myVar ]]', 'cool');

Above code matches string inside [[ ... ]] and will yield

newStr = 'This is cool'

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Documentation