public static RoutePattern Parse(string pattern)
{
if (pattern == null)
{
throw new ArgumentNullException(nameof(pattern));
}
var trimmedPattern = TrimPrefix(pattern);
var context = new TemplateParserContext(trimmedPattern);
var segments = new List <RoutePatternPathSegment>();
while (context.MoveNext())
{
var i = context.Index;
if (context.Current == Separator)
{
// If we get here is means that there's a consecutive '/' character.
// Templates don't start with a '/' and parsing a segment consumes the separator.
throw new RoutePatternException(pattern, Resources.TemplateRoute_CannotHaveConsecutiveSeparators);
}
if (!ParseSegment(context, segments))
{
throw new RoutePatternException(pattern, context.Error);
}
// A successful parse should always result in us being at the end or at a separator.
Debug.Assert(context.AtEnd() || context.Current == Separator);
if (context.Index <= i)
{
throw new InvalidProgramException("Infinite loop in the parser. This is a bug.");
}
}
if (IsAllValid(context, segments))
{
var builder = RoutePatternBuilder.Create(pattern);
for (var i = 0; i < segments.Count; i++)
{
builder.PathSegments.Add(segments[i]);
}
return(builder.Build());
}
else
{
throw new RoutePatternException(pattern, context.Error);
}
}
private static bool ParseSegment(TemplateParserContext context, List <RoutePatternPathSegment> segments)
{
Debug.Assert(context != null);
Debug.Assert(segments != null);
var parts = new List <RoutePatternPart>();
while (true)
{
var i = context.Index;
if (context.Current == OpenBrace)
{
if (!context.MoveNext())
{
// This is a dangling open-brace, which is not allowed
context.Error = Resources.TemplateRoute_MismatchedParameter;
return(false);
}
if (context.Current == OpenBrace)
{
// This is an 'escaped' brace in a literal, like "{{foo"
context.Back();
if (!ParseLiteral(context, parts))
{
return(false);
}
}
else
{
// This is a parameter
context.Back();
if (!ParseParameter(context, parts))
{
return(false);
}
}
}
else
{
if (!ParseLiteral(context, parts))
{
return(false);
}
}
if (context.Current == Separator || context.AtEnd())
{
// We've reached the end of the segment
break;
}
if (context.Index <= i)
{
throw new InvalidProgramException("Infinite loop in the parser. This is a bug.");
}
}
if (IsSegmentValid(context, parts))
{
segments.Add(new RoutePatternPathSegment(null, parts.ToArray()));
return(true);
}
else
{
return(false);
}
}
