public static BoundExpression Parse(string expression,
Func <string, bool, string, IValueProvider> contextualResource)
{
if (expression == null)
{
throw new ArgumentNullException(nameof(expression));
}
var i = 0;
if (expression.StartsWith("\\"))
{
i = 1;
}
else if (expression.StartsWith("@"))
{
return(new BoundExpression(expression.Substring(1)));
}
var resources = new List <IValueProvider>();
var stringFormat = new StringBuilder();
var resourceType = new StringBuilder();
var resourceName = new StringBuilder();
var resourceConverter = new StringBuilder();
var resourceFormat = new StringBuilder();
var oneTimeBind = false;
var length = expression.Length;
char c;
outside:
if (i == length)
{
var format = stringFormat.ToString();
return(new BoundExpression(resources, format == "{0}" ? null : format));
}
c = expression[i];
if (c == '{')
{
stringFormat.Append('{');
if (++i == expression.Length)
{
throw new FormatException("Invalid unescaped '{' at end of input.");
}
if (expression[i] == '{')
{
i++;
stringFormat.Append('{');
goto outside;
}
goto readResource;
}
if (c == '}')
{
stringFormat.Append('}');
if (++i == expression.Length)
{
throw new FormatException("Invalid unescaped '}' at end of input.");
}
if (expression[i] == '}')
{
i++;
stringFormat.Append('}');
goto outside;
}
throw new FormatException("Invalid unescaped '}'.");
}
stringFormat.Append(c);
i++;
goto outside;
readResource:
// A leading ^ indicates one time binding for contextual resources.
if (expression[i] == '^')
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
oneTimeBind = true;
}
// Resource type.
while (char.IsLetter(c = expression[i]))
{
resourceType.Append(c);
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
}
// Skip whitespace.
while (char.IsWhiteSpace(expression[i]))
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
}
// Resource name.
if (expression[i] == '\'')
{
i++;
if (i == length)
{
throw new FormatException("Unexpected end of input.");
}
while ((c = expression[i]) != '\'')
{
resourceName.Append(c);
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
}
i++;
if (i == length)
{
throw new FormatException("Unexpected end of input.");
}
}
else
{
while ((c = expression[i]) != ',' && c != ':' && c != '|')
{
if (c == '{')
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
if (expression[i] != '{')
{
throw new FormatException("Invalid unescaped '{'.");
}
}
else if (c == '}')
{
if (++i == length)
{
goto addResource;
}
if (expression[i] != '}')
{
goto addResource;
}
}
resourceName.Append(c);
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
}
}
// Skip whitespace between name and converter/format/end.
while (char.IsWhiteSpace(expression[i]))
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
}
c = expression[i];
if (c == '}')
{
// Resource can close at this point assuming no converter and no string format.
if (++i == length)
{
goto addResource;
}
if (expression[i] != '}')
{
goto addResource;
}
throw new FormatException("Invalid '}}' sequence.");
}
// Value converter, read while character is letter.
if (c == '|')
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
while (char.IsLetter(c = expression[i]))
{
resourceConverter.Append(c);
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
}
// Skip whitespace between converter to parameter/format/end.
while (char.IsWhiteSpace(expression[i]))
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
}
// Check for value converter parameter.
if (c == '(')
{
do
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
} while (char.IsWhiteSpace(expression[i]));
c = expression[i];
if (c == '\'')
{
resourceConverter.Append(':');
var converterParameter = new StringBuilder();
while (true)
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
c = expression[i];
if (c != '\'')
{
converterParameter.Append(c);
}
else
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
c = expression[i];
if (c == '\'')
{
converterParameter.Append('\'');
}
else
{
// End of string
while (char.IsWhiteSpace(expression[i]))
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
}
c = expression[i];
if (c != ')')
{
throw new FormatException(
"Expected closing parenthesis after converter parameter.");
}
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
c = expression[i];
break;
}
}
}
resourceConverter
.Append('\'')
.Append(converterParameter);
}
else if (c != ')')
{
resourceConverter.Append(':');
var converterParameter = new StringBuilder();
converterParameter.Append(c);
while (true)
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
c = expression[i];
if (char.IsWhiteSpace(c))
{
do
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
} while (char.IsWhiteSpace(expression[i]));
c = expression[i];
if (c != ')')
{
throw new FormatException("Expected closing parenthesis after converter parameter.");
}
}
if (c == ')')
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
c = expression[i];
break;
}
converterParameter.Append(c);
}
resourceConverter.Append(converterParameter.ToString().ToLowerInvariant());
}
}
// Skip whitespace between converter/parameter to format/end.
while (char.IsWhiteSpace(expression[i]))
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
}
if (c == '}')
{
if (++i == length)
{
goto addResource;
}
if (expression[i] != '}')
{
goto addResource;
}
throw new FormatException("Converter name cannot contain braces.");
}
}
// String format, read until single '}'.
if (c == ',' || c == ':')
{
resourceFormat.Append(c);
while (true)
{
if (++i == length)
{
throw new FormatException("Unexpected end of input.");
}
c = expression[i];
if (c == '}')
{
if (++i == length)
{
goto addResource;
}
if (expression[i] != '}')
{
goto addResource;
}
resourceFormat.Append('}');
}
resourceFormat.Append(c);
}
}
throw new FormatException($"Invalid character '{c}'");
addResource:
var key = resourceName.ToString();
IValueProvider resource;
var converter = resourceConverter.ToString();
var resourceTypeString = resourceType.ToString();
switch (resourceTypeString)
{
case "Binding":
resource = new PropertyBinding(key, false, converter);
break;
case "Property":
resource = new PropertyBinding(key, true, converter);
break;
case "StaticResource":
resource = new StaticResource(key, converter);
break;
case "DynamicResource":
resource = new DynamicResource(key, converter);
break;
case "ContextBinding":
resource = new ContextPropertyBinding(key, false, converter);
break;
case "ContextProperty":
resource = new ContextPropertyBinding(key, true, converter);
break;
case "Env":
resource = new EnvironmentBinding(key, oneTimeBind, converter);
break;
case "FileBinding":
resource = new FileBinding(key, true, converter);
break;
case "File":
resource = new FileBinding(key, false, converter);
break;
default:
resource = contextualResource?.Invoke(resourceTypeString + key, oneTimeBind, converter);
if (resource != null)
{
break;
}
throw new FormatException("Invalid resource type.");
}
var index = resources.IndexOf(resource);
if (index == -1)
{
index = resources.Count;
resources.Add(resource);
}
stringFormat.Append(index);
if (resourceFormat.Length != 0)
{
stringFormat.Append(resourceFormat);
}
stringFormat.Append('}');
resourceType.Clear();
resourceName.Clear();
resourceFormat.Clear();
resourceConverter.Clear();
oneTimeBind = false;
goto outside;
}