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//
// System.IO.SearchPattern.cs: Filename glob support.
//
// Author:
// Dan Lewis (dihlewis@yahoo.co.uk)
//
// (C) 2002
//
using System;
namespace System.IO {
// FIXME: there's a complication with this algorithm under windows.
// the pattern '*.*' matches all files (i think . matches the extension),
// whereas under UNIX it should only match files containing the '.' character.
class SearchPattern {
public SearchPattern (string pattern) : this (pattern, false) { }
public SearchPattern (string pattern, bool ignore)
{
this.ignore = ignore;
Compile (pattern);
}
public bool IsMatch (string text)
{
return Match (ops, text, 0);
}
// private
private Op ops; // the compiled pattern
private bool ignore; // ignore case
private void Compile (string pattern)
{
if (pattern == null || pattern.IndexOfAny (InvalidChars) >= 0)
throw new ArgumentException ("Invalid search pattern.");
if (pattern == "*") { // common case
ops = new Op (OpCode.True);
return;
}
ops = null;
int ptr = 0;
Op last_op = null;
while (ptr < pattern.Length) {
Op op;
switch (pattern [ptr]) {
case '?':
op = new Op (OpCode.AnyChar);
++ ptr;
break;
case '*':
op = new Op (OpCode.AnyString);
++ ptr;
break;
default:
op = new Op (OpCode.ExactString);
int end = pattern.IndexOfAny (WildcardChars, ptr);
if (end < 0)
end = pattern.Length;
op.Argument = pattern.Substring (ptr, end - ptr);
if (ignore)
op.Argument = op.Argument.ToLower ();
ptr = end;
break;
}
if (last_op == null)
ops = op;
else
last_op.Next = op;
last_op = op;
}
if (last_op == null)
ops = new Op (OpCode.End);
else
last_op.Next = new Op (OpCode.End);
}
private bool Match (Op op, string text, int ptr)
{
while (op != null) {
switch (op.Code) {
case OpCode.True:
return true;
case OpCode.End:
if (ptr == text.Length)
return true;
return false;
case OpCode.ExactString:
int length = op.Argument.Length;
if (ptr + length > text.Length)
return false;
string str = text.Substring (ptr, length);
if (ignore)
str = str.ToLower ();
if (str != op.Argument)
return false;
ptr += length;
break;
case OpCode.AnyChar:
if (++ ptr > text.Length)
return false;
break;
case OpCode.AnyString:
while (ptr <= text.Length) {
if (Match (op.Next, text, ptr))
return true;
++ ptr;
}
return false;
}
op = op.Next;
}
return true;
}
// private static
private static readonly char [] WildcardChars = { '*', '?' };
private static readonly char [] InvalidChars = { Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar };
private class Op {
public Op (OpCode code)
{
this.Code = code;
this.Argument = null;
this.Next = null;
}
public OpCode Code;
public string Argument;
public Op Next;
}
private enum OpCode {
ExactString, // literal
AnyChar, // ?
AnyString, // *
End, // end of pattern
True // always succeeds
};
}
}
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