/// <summary>
/// Helper method for saving possible chars used in regexp according of its structure.
/// </summary>
/// <param name="sb">stringbuilder used too store data about that alphabet.</param>
/// <returns></returns>
private StringBuilder ToStringBuilderForUsedAlphabet(StringBuilder sb)
{
switch (kind)
{
case Kind.RegexpUnion:
case Kind.RegexpConcatenation:
exp1.ToStringBuilderForUsedAlphabet(sb);
exp2.ToStringBuilderForUsedAlphabet(sb);
break;
case Kind.RegexpIntersection:
var sb1 = new StringBuilder();
var sb2 = new StringBuilder();
var st1 = exp1.ToStringBuilderForUsedAlphabet(sb1).ToString().ToCharArray();
var st2 = exp2.ToStringBuilderForUsedAlphabet(sb2).ToString().ToCharArray();
sb.Append(st1.Intersect(st2).Distinct());
break;
case Kind.RegexpOptional:
case Kind.RegexpRepeat:
case Kind.RegexpRepeatMin:
case Kind.RegexpRepeatMinMax:
exp1.ToStringBuilderForUsedAlphabet(sb);
break;
case Kind.RegexpComplement:
var sbc = new StringBuilder();
var stc = exp1.ToStringBuilderForUsedAlphabet(sbc).ToString().ToCharArray();
if (this.anyCharAlphabet != null)
{
sb.Append(this.anyCharAlphabet.ToCharArray().Where(x => !stc.Contains(x)));
}
else
{
var sba = new StringBuilder();
var sta = MakeAnyPrintableASCIIChar(this.anyCharAlphabet).ToStringBuilderForUsedAlphabet(sba).ToString().ToCharArray();
sb.Append(sta.Where(x => !stc.Contains(x)));
}
break;
case Kind.RegexpChar:
sb.Append(c);
break;
case Kind.RegexpCharRange:
for (char i = this.@from; i <= this.to; i++)
{
sb.Append(i);
}
break;
case Kind.RegexpAnyChar:
case Kind.RegexpAnyString:
if (this.anyCharAlphabet != null)
{
sb.Append(this.anyCharAlphabet);
}
else
{
MakeAnyPrintableASCIIChar(this.anyCharAlphabet).ToStringBuilderForUsedAlphabet(sb);
}
break;
case Kind.RegexpEmpty:
if (this.anyCharAlphabet != null)
{
foreach (char ch in this.anyCharAlphabet)
{
if (Char.IsWhiteSpace(ch))
{
sb.Append(ch);
}
}
}
else
{
sb.Append(' '); // in ' ' to '~' there is only one whitespace, and that is space.
}
break;
case Kind.RegexpString:
case Kind.RegexpAutomaton:
sb.Append(s);
break;
case Kind.RegexpInterval:
string s1 = Convert.ToDecimal(min).ToString();
string s2 = Convert.ToDecimal(max).ToString();
sb.Append(s1).Append(s2);
break;
}
return(sb);
}