/// <summary>
/// Parses the next parameter in the specified <paramref name="expr"/>.
/// The returned value will indicate the index in this string following
/// the parameter declaration.
/// </summary>
/// <remarks>
/// Parses in the specified <paramref name="expr"/> beginning at the specified
/// <paramref name="index"/> a XAML markup extension parameter specification
/// of the form
/// <code>
/// 1)
/// [Name]=[Value]
/// </code>
/// or
/// <code>
/// 2)
/// [Value]
/// </code>
/// The value itself may be a simple string value or an instantiation of
/// another element, surrounded by { and } characters.
/// If form 1 is found, the returned parameter
/// <paramref name="name"/> will contain the parsed name part, if form 2 is
/// found, the <paramref name="name"/> parameter will be null.
/// In both forms the <paramref name="value"/> parameter will contain the
/// parsed value string.
/// </remarks>
/// <returns>The index in the <paramref name="expr"/> string following
/// the parameter declaration.</returns>
private static int ParseParameter(string expr, int index, out string name, out string value)
{
index = ParserHelper.SkipSpaces(expr, index);
if (index >= expr.Length)
{
throw new XamlParserException("Object instantiation expression '{0}': '=' expected at position {1}", expr, index);
}
string nameOrValue;
index = ParseNameOrValue(expr, index, out nameOrValue);
index = ParserHelper.SkipSpaces(expr, index);
if (index < expr.Length && expr[index] == '=')
{
name = nameOrValue;
index += 1;
index = ParseNameOrValue(expr, index, out value);
index = ParserHelper.SkipSpaces(expr, index);
}
else
{
name = null;
value = nameOrValue;
}
return(index);
}
/// <summary>
/// Parses an expression in an attribute value syntax for instantiating an element
/// like a markup extension. The specified expression string must not contain
/// the starting { and ending } characters.
/// </summary>
/// <param name="expr">Expression representing an object instantiation.
/// This expression has the syntax
/// <code>
/// Object-Instantiation := [Expression-Name] <[Property]=[Value]<, ...>>
/// </code>
/// or
/// <code>
/// Object-Instantiation := [Expression-Name] <[Value]<, ...>>
/// </code>
/// Every parameter itself can again be a simple value assignment or an
/// instantiation of another element.
/// In this case, the according value expression has the syntax
/// <code>
/// [Value]={[Object-Instantiation]}
/// </code></param>
/// <param name="extensionName">Will be assigned to the name of the element
/// instantiate.</param>
/// <param name="parameters">Will contain a list of parameter assignments.</param>
/// <param name="namedParams">Will contain the information, if the parameters
/// are given in a <c>name = value</c> syntax or in a <c>param</c> syntax.
/// Mixed syntax forms for different parameters are not supported.
/// If no parameters were found, <paramref name="namedParams"/> will be set
/// to <c>false</c>.</param>
public static void ParseInstantiationExpression(string expr,
out string extensionName, out IList <KeyValuePair <string, string> > parameters,
out bool namedParams)
{
parameters = new List <KeyValuePair <string, string> >();
int i = expr.IndexOf(' ');
if (i == -1)
{
extensionName = expr;
namedParams = false;
}
else
{
extensionName = expr.Substring(0, i);
i = ParserHelper.SkipSpaces(expr, i);
bool?allNamedParams = null;
while (i < expr.Length)
{
string name;
string value;
i = ParseParameter(expr, i, out name, out value);
parameters.Add(new KeyValuePair <string, string>(name, value));
bool hasName = !string.IsNullOrEmpty(name);
if (allNamedParams == null)
{
allNamedParams = hasName;
}
else if (allNamedParams.Value != hasName)
{
throw new XamlParserException("Object instantiation expression '{0}', position {1}: mixed named and unnamed parameters are not allowed", expr, i);
}
i = ParserHelper.SkipSpaces(expr, i);
if (i >= expr.Length)
{
break; // End of expression reached - all parameters processed
}
if (expr[i] != ',')
{
throw new XamlParserException("Object instantiation expression syntax '{0}' is invalid at position {1}", expr, i);
}
i++;
i = ParserHelper.SkipSpaces(expr, i);
if (i >= expr.Length)
{
throw new XamlParserException("Object instantiation expression '{0}': parameter expected at position {1}", expr, i);
}
}
namedParams = (allNamedParams ?? false); // Default when no params were parsed: namedParams == false
}
}
protected static int ParsePathSegment(IParserContext context, string path, int pos, out IPathSegment result)
{
pos = ParserHelper.SkipSpaces(path, pos);
if (path[pos] == '[')
{ // Indexer expression
object[] indices;
pos = ParseIndices(context, path, pos, out indices);
result = new IndexerPathSegment(indices);
return(pos);
}
if (path[pos] == '(')
{ // Attached property
int bracket = path.IndexOf(")", pos);
if (bracket == -1)
{
throw new XamlParserException("Path '{0}': ')' expected", path);
}
int dot = path.IndexOf('.', pos);
if (dot == -1 || dot > bracket)
{
throw new XamlParserException("Path '{0}': Attached property expected", path);
}
string propertyProvider = path.Substring(pos + 1, dot - pos - 1);
string propertyName = path.Substring(dot + 1, bracket - dot - 1);
string namespaceURI;
context.LookupNamespace(propertyProvider, out propertyProvider, out namespaceURI);
result = new AttachedPropertyPathSegment(context, propertyProvider, propertyName, namespaceURI);
return(bracket + 1);
}
// Member
int end = path.IndexOfAny(new char[] { '.', '[' }, pos);
if (end == -1)
{
end = path.Length;
}
result = new MemberPathSegment(path.Substring(pos, end - pos));
if (path.IndexOf('[', pos) == end)
{ // Index follows member name
object[] indices;
end = ParseIndices(context, path, end, out indices);
((MemberPathSegment)result).SetIndices(indices);
}
return(end);
}
