/// <summary>
/// Parses the input for optionals. The resulting collection contains only literal and optinal segments which are expanded into the full tree later by the <see cref="M:Expand"/> method.
/// </summary>
/// <param name="input">The input path.</param>
/// <returns>Returns the collection of literal and optional segments.</returns>
protected virtual PathSegmentCollection ParseOptionals(string input)
{
Action <StringBuilder, Stack <PathSegmentCollection> > flush = (b, s) =>
{
if (b.Length > 0)
{
s.Peek().Add(new LiteralPathSegment(b.ToString()));
b.Length = 0;
}
};
var sb = new StringBuilder();
var stack = new Stack <PathSegmentCollection>();
stack.Push(new PathSegmentCollection());
for (int i = 0; i < input.Length; i++)
{
var ch = input[i];
if (ch == '(')
{
flush(sb, stack);
var item = new OptionalPathSegment();
stack.Peek().Add(item);
stack.Push(item.Segments);
}
else if (ch == ')')
{
if (stack.Count <= 1)
{
throw new FormatException("The number of closing braces is greater than the number of opening.");
}
flush(sb, stack);
stack.Pop();
}
else
{
sb.Append(ch);
}
}
if (stack.Count > 1)
{
throw new FormatException(String.Format("Missing {0} closing brace(s).", stack.Count - 1));
}
flush(sb, stack);
return(stack.Peek());
}
/// <summary>
/// Expands the specified segment collection which contains only optinal and literal segments.
/// The optional segments are processed recursively and the literals are parsed for parameters.
/// </summary>
/// <param name="collection">The collection of segments to expand.</param>
/// <param name="constraints">The constraints.</param>
/// <param name="parameters">The parameters hash set to track the uniqueness.</param>
/// <returns>Returns the expanded path segments tree.</returns>
protected virtual PathSegmentCollection Expand(PathSegmentCollection collection, IDictionary <string, object> constraints, HashSet <string> parameters)
{
var result = new PathSegmentCollection();
foreach (var item in collection)
{
if (item is LiteralPathSegment)
{
var staticItem = (LiteralPathSegment)item;
var list = Parse(staticItem.Text, constraints, parameters);
result.AddRange(list);
}
else if (item is OptionalPathSegment)
{
var optItem = new OptionalPathSegment();
result.Add(optItem);
var inner = Expand(item.Segments, constraints, parameters);
optItem.Segments.AddRange(inner);
}
}
return(result);
}
