/// <summary>
/// Build regex pattern that captures same parts from filename string.
///
/// For example "localization{-Culture}.ini" translates to regex "localization(-(?<Culture>.*))?.ini".
/// This can be matched against filename "localization-en.ini" with group m.Group["Culture"].Value == "en".
/// </summary>
/// <paramref name="pattern"/>
/// <paramref name="filledParameters"/>>
/// <returns>regex</returns>
public static string BuildRegexString(this ILinePattern pattern, IReadOnlyDictionary <string, string> filledParameters, BuildRegexFlags flags = BuildRegexFlags.All)
{
StringBuilder sb = new StringBuilder();
sb.Append('^');
for (int i = 0; i < pattern.AllParts.Length; i++)
{
ILinePatternPart part = pattern.AllParts[i];
// Add regular part
if (part.Text != null)
{
sb.Append(Escape(part.Text, flags, BuildRegexFlags.Escape_NonPart)); continue;
}
string prefilled_value;
if (filledParameters != null && filledParameters.TryGetValue(part.Identifier, out prefilled_value) && prefilled_value != null)
{
if (part.PrefixSeparator != null)
{
sb.Append(Escape(part.PrefixSeparator, flags, BuildRegexFlags.Escape_Prefix));
}
sb.Append(Escape(prefilled_value, flags, BuildRegexFlags.Escape_Identifier));
if (part.PostfixSeparator != null)
{
sb.Append(Escape(part.PostfixSeparator, flags, BuildRegexFlags.Escape_Postfix));
}
}
else
{
sb.Append("(");
if (part.PrefixSeparator != null)
{
sb.Append(Escape(part.PrefixSeparator, flags, BuildRegexFlags.Escape_Prefix));
}
sb.Append("(?<");
sb.Append(Escape(part.Identifier, flags, BuildRegexFlags.Escape_Identifier));
sb.Append('>');
// Append type specific pattern
Regex part_pattern = part.Regex;
string pattern_text = part_pattern.ToString();
int start = 0, end = pattern_text.Length;
if (pattern_text.Length > 0 && pattern_text[start] == '^')
{
start++;
}
if (pattern_text.Length > 0 && pattern_text[end - 1] == '$')
{
end--;
}
if (start < end)
{
sb.Append(pattern_text.Substring(start, end - start));
}
sb.Append(')');
if (part.PostfixSeparator != null)
{
sb.Append(Escape(part.PostfixSeparator, flags, BuildRegexFlags.Escape_Postfix));
}
sb.Append(")");
if (!part.Required)
{
sb.Append('?');
}
}
}
sb.Append('$');
return(sb.ToString());
}
internal static string Escape(string txt, BuildRegexFlags flags, BuildRegexFlags requiredFlag) => (flags & requiredFlag) != 0 ? Regex.Escape(txt) : txt;
