/// <summary>
/// Gets the scope required to evaluate the condition.
/// </summary>
/// <param name="expression">Condition expression.</param>
/// <returns>Element attribute scope.</returns>
private ElementAttributeScope GetRequiredScope(IConditionExpression expression)
{
ElementAttributeScope scope = ElementAttributeScope.Element;
if (expression != null)
{
ElementAttributeExpression attributeExpression = expression as ElementAttributeExpression;
if (attributeExpression != null)
{
scope = attributeExpression.Scope;
}
else
{
ElementAttributeScope leftScope = GetRequiredScope(expression.Left);
ElementAttributeScope rightScope = GetRequiredScope(expression.Right);
if (leftScope > rightScope)
{
scope = leftScope;
}
else
{
scope = rightScope;
}
}
}
return(scope);
}
/// <summary>
/// Creates a new element attribute expression.
/// </summary>
/// <param name="elementAttribute">The element attribute.</param>
/// <param name="scope">The scope.</param>
public ElementAttributeExpression(ElementAttributeType elementAttribute, ElementAttributeScope scope)
{
_elementAttributeType = elementAttribute;
_elementScope = scope;
}
/// <summary>
/// Parses and expression to an expression tree.
/// </summary>
/// <param name="expression">Condition expression text.</param>
/// <returns>A condition expression instance.</returns>
public IConditionExpression Parse(string expression)
{
const int DefaultExpressionLength = 128;
IConditionExpression conditionExpression = null;
if (expression == null)
{
throw new ArgumentNullException("expression");
}
else if (expression.Trim().Length == 0)
{
throw new ArgumentException("expression");
}
List <IConditionExpression> nodes = new List <IConditionExpression>();
StringReader reader = new StringReader(expression);
StringBuilder expressionBuilder = new StringBuilder(DefaultExpressionLength);
bool inString = false;
bool inAttribute = false;
int depth = 0;
int data = reader.Read();
while (data > 0)
{
char ch = (char)data;
char nextCh = (char)reader.Peek();
if (inString && ch != '\'')
{
expressionBuilder.Append(ch);
}
else
{
switch (ch)
{
case ' ':
case '\t':
case '\r':
case '\n':
// Eat whitespace
break;
case ExpressionPrefix:
CheckForInvalidOperator(expression, expressionBuilder);
if (nextCh == ExpressionStart)
{
inAttribute = true;
reader.Read();
}
break;
case '=':
if (nextCh == '=')
{
nodes.Add(new OperatorExpressionPlaceholder(BinaryExpressionOperator.Equal));
reader.Read();
}
else if (nextCh == '~')
{
nodes.Add(new OperatorExpressionPlaceholder(BinaryExpressionOperator.Matches));
reader.Read();
}
break;
case '!':
if (nextCh == '=')
{
nodes.Add(new OperatorExpressionPlaceholder(BinaryExpressionOperator.NotEqual));
reader.Read();
}
else
{
expressionBuilder.Append(ch);
}
break;
case ':':
nodes.Add(new OperatorExpressionPlaceholder(BinaryExpressionOperator.Contains));
reader.Read();
break;
case 'O':
if (nextCh == 'r' && !inAttribute && !inString)
{
nodes.Add(new OperatorExpressionPlaceholder(BinaryExpressionOperator.Or));
reader.Read();
}
else
{
expressionBuilder.Append(ch);
}
break;
case 'A':
if (nextCh == 'n' && !inAttribute && !inString)
{
reader.Read();
nextCh = (char)reader.Peek();
if (nextCh == 'd')
{
nodes.Add(new OperatorExpressionPlaceholder(BinaryExpressionOperator.And));
reader.Read();
}
}
else
{
expressionBuilder.Append(ch);
}
break;
case ExpressionEnd:
if (inAttribute)
{
string attribute = expressionBuilder.ToString();
expressionBuilder = new StringBuilder(DefaultExpressionLength);
ElementAttributeScope elementScope = ElementAttributeScope.Element;
bool isFileExpression = false;
int separatorIndex = attribute.LastIndexOf(ScopeSeparator);
if (separatorIndex > 0)
{
try
{
string attributeScope = attribute.Substring(0, separatorIndex);
attribute = attribute.Substring(separatorIndex + 1);
if (attributeScope == FileAttributeScope)
{
isFileExpression = true;
}
else
{
elementScope = (ElementAttributeScope)
Enum.Parse(typeof(ElementAttributeScope), attributeScope);
}
}
catch (ArgumentException ex)
{
OnInvalidExpression(expression, "Unknown attribute scope: {0}", ex.Message);
}
}
if (isFileExpression)
{
FileAttributeType fileAttribute = FileAttributeType.None;
try
{
fileAttribute = (FileAttributeType)
Enum.Parse(typeof(FileAttributeType), attribute);
}
catch (ArgumentException ex)
{
OnInvalidExpression(expression, "Unknown attribute: {0}", ex.Message);
}
FileAttributeExpression attributeExpresion = new FileAttributeExpression(
fileAttribute);
nodes.Add(attributeExpresion);
}
else
{
ElementAttributeType elementAttribute = ElementAttributeType.None;
try
{
elementAttribute = (ElementAttributeType)
Enum.Parse(typeof(ElementAttributeType), attribute);
}
catch (ArgumentException ex)
{
OnInvalidExpression(expression, "Unknown attribute: {0}", ex.Message);
}
ElementAttributeExpression attributeExpresion = new ElementAttributeExpression(
elementAttribute, elementScope);
nodes.Add(attributeExpresion);
}
inAttribute = false;
}
else if (expressionBuilder.Length > 0 && nodes.Count > 0)
{
IConditionExpression innerExpression = nodes[nodes.Count - 1];
nodes.RemoveAt(nodes.Count - 1);
string unaryOperatorString = expressionBuilder.ToString().Trim();
expressionBuilder = new StringBuilder(DefaultExpressionLength);
UnaryExpressionOperator?unaryOperator = null;
if (unaryOperatorString == "!")
{
unaryOperator = UnaryExpressionOperator.Negate;
}
else
{
OnInvalidExpression(expression,
"Invalid operator {0}", unaryOperatorString);
}
UnaryOperatorExpression unaryOperatorExpression = new UnaryOperatorExpression(
unaryOperator.Value, innerExpression);
nodes.Add(unaryOperatorExpression);
depth--;
}
else
{
depth--;
}
break;
case ExpressionStart:
IConditionExpression nestedExpression = null;
StringBuilder childExpressionBuilder = new StringBuilder(DefaultExpressionLength);
data = reader.Read();
ch = (char)data;
nextCh = (char)reader.Peek();
depth++;
while (data > 0)
{
if (ch == ExpressionPrefix && nextCh == ExpressionStart)
{
inAttribute = true;
childExpressionBuilder.Append(ExpressionPrefix);
data = reader.Read();
childExpressionBuilder.Append(ExpressionStart);
}
else if (ch == ExpressionStart && !inAttribute)
{
depth++;
childExpressionBuilder.Append(ExpressionStart);
}
else if (nextCh == ExpressionEnd)
{
childExpressionBuilder.Append(ch);
if (inAttribute || depth > 1)
{
if (inAttribute)
{
inAttribute = false;
}
else if (depth > 1)
{
depth--;
}
}
else
{
break;
}
}
else
{
childExpressionBuilder.Append(ch);
}
data = reader.Read();
ch = (char)data;
nextCh = (char)reader.Peek();
}
try
{
nestedExpression = Parse(childExpressionBuilder.ToString());
}
catch (ArgumentException)
{
OnInvalidExpression(expression);
}
nodes.Add(nestedExpression);
break;
case '\'':
if (inString)
{
if (nextCh == '\'')
{
expressionBuilder.Append(ch);
reader.Read();
}
else
{
string str = expressionBuilder.ToString();
expressionBuilder = new StringBuilder(DefaultExpressionLength);
StringExpression stringExpression = new StringExpression(str);
nodes.Add(stringExpression);
inString = false;
}
}
else
{
CheckForInvalidOperator(expression, expressionBuilder);
inString = true;
}
break;
default:
expressionBuilder.Append(ch);
break;
}
}
data = reader.Read();
}
if (inString)
{
OnInvalidExpression(expression, "Expected '");
}
else if (inAttribute || depth > 0)
{
OnInvalidExpression(expression, "Expected )");
}
else if (depth < 0)
{
OnInvalidExpression(expression, "Unmatched )");
}
//
// Assembly the flat list of expressions and expression placeholders into an
// expression tree.
//
conditionExpression = AssembleExpressionTree(nodes.AsReadOnly(), expression);
return(conditionExpression);
}
/// <summary>
/// Creates a new element attribute expression.
/// </summary>
/// <param name="elementAttribute">The element attribute.</param>
/// <param name="scope">The scope.</param>
public ElementAttributeExpression(ElementAttributeType elementAttribute, ElementAttributeScope scope)
{
_elementAttributeType = elementAttribute;
_elementScope = scope;
}
/// <summary>
/// Creates a new ElementFilter.
/// </summary>
/// <param name="conditionExpression">The condition expression.</param>
public ElementFilter(string conditionExpression)
{
_conditionExpression = ConditionExpressionParser.Instance.Parse(conditionExpression);
_requiredScope = GetRequiredScope(_conditionExpression);
}
/// <summary>
/// Creates a new ElementFilter.
/// </summary>
/// <param name="conditionExpression">The condition expression.</param>
public ElementFilter(string conditionExpression)
{
_conditionExpression = ConditionExpressionParser.Instance.Parse(conditionExpression);
_requiredScope = GetRequiredScope(_conditionExpression);
}
