| public static FirstGroup ( string expression ) : TextSpan? | ||
| expression | string | |
| return | TextSpan? | |
public static TextSpan? FirstGroup(string expression)
{
var start = -1;
var end = -1;
bool isEscapedCharacter = false;
var nestingLevel = 0;
for (int i = 0; i < expression.Length; ++i)
{
if (expression[i] == '\\' && !isEscapedCharacter)
{
isEscapedCharacter = true;
continue;
}
if (isEscapedCharacter)
{
isEscapedCharacter = false;
continue;
}
if (expression[i] == '(')
{
if (nestingLevel == 0) start = i;
nestingLevel++;
}
else if (expression[i] == ')')
{
nestingLevel--;
if (nestingLevel == 0)
{
end = i;
break;
}
}
isEscapedCharacter = false;
}
if(start < 0 || end < 0) return null;
return new TextSpan() {
Offset = start,
Length = end - start + 1
};
}