Cet extrait imitera le comportement et la syntaxe de Sql LIKE. Vous pouvez envelopper dans une lambda ou une méthode extension de votre propre pour une utilisation dans une déclaration Linq:
public static bool IsSqlLikeMatch(string input, string pattern)
{
/* Turn "off" all regular expression related syntax in
* the pattern string. */
pattern = Regex.Escape(pattern);
/* Replace the SQL LIKE wildcard metacharacters with the
* equivalent regular expression metacharacters. */
pattern = pattern.Replace("%", ".*?").Replace("_", ".");
/* The previous call to Regex.Escape actually turned off
* too many metacharacters, i.e. those which are recognized by
* both the regular expression engine and the SQL LIKE
* statement ([...] and [^...]). Those metacharacters have
* to be manually unescaped here. */
pattern = pattern.Replace(@"\[", "[").Replace(@"\]", "]").Replace(@"\^", "^");
return Regex.IsMatch(input, pattern, RegexOptions.IgnoreCase);
}
A malmené ensemble méthode d'extension qui fonctionnerait comme méthode IEnumerable<T>.Where
:
public static IEnumerable<T> Like<T>(this IEnumerable<T> source, Func<T, string> selector, string pattern)
{
return source.Where(t => IsSqlLikeMatch(selector(t), pattern));
}
qui serait en tour, vous permettra de formater votre déclaration comme ceci:
string pattern = "%ine%e";
var res = list.Like(s => s, pattern);
EDIT Une impro mise en œuvre, si quelqu'un tombe sur et que vous voulez utiliser ce code. Il convertit et compile l'expression regex une fois pour chaque item et la conversion de LIKE en regex ci-dessus a quelques bugs.
public static class LikeExtension
{
public static IEnumerable<T> Like<T>(this IEnumerable<T> source, Func<T, string> selector, string pattern)
{
var regex = new Regex(ConvertLikeToRegex(pattern), RegexOptions.IgnoreCase);
return source.Where(t => IsRegexMatch(selector(t), regex));
}
static bool IsRegexMatch(string input, Regex regex)
{
if (input == null)
return false;
return regex.IsMatch(input);
}
static string ConvertLikeToRegex(string pattern)
{
StringBuilder builder = new StringBuilder();
// Turn "off" all regular expression related syntax in the pattern string
// and add regex begining of and end of line tokens so '%abc' and 'abc%' work as expected
builder.Append("^").Append(Regex.Escape(pattern)).Append("$");
/* Replace the SQL LIKE wildcard metacharacters with the
* equivalent regular expression metacharacters. */
builder.Replace("%", ".*").Replace("_", ".");
/* The previous call to Regex.Escape actually turned off
* too many metacharacters, i.e. those which are recognized by
* both the regular expression engine and the SQL LIKE
* statement ([...] and [^...]). Those metacharacters have
* to be manually unescaped here. */
builder.Replace(@"\[", "[").Replace(@"\]", "]").Replace(@"\^", "^");
// put SQL LIKE wildcard literals back
builder.Replace("[.*]", "[%]").Replace("[.]", "[_]");
return builder.ToString();
}
}
Wow! Sa réponse la plus impressionnante que les autres! Merci beaucoup –