/// <summary>Attempts to parse key values from the specified text.</summary>
/// <param name='text'>Text to parse (not null).</param>
/// <param name="allowNamedValues">Set to true if the parser should accept named values
/// so syntax like Name='value'. If this is false, the parsing will fail on such constructs.</param>
/// <param name="allowNull">Set to true if the parser should accept null values.
/// If set to false, the parser will fail on null values.</param>
/// <param name='instance'>After invocation, the parsed key instance.</param>
/// <returns>
/// true if the key instance was parsed; false if there was a
/// syntactic error.
/// </returns>
/// <remarks>
/// The returned instance contains only string values. To get typed values, a call to
/// <see cref="TryConvertValues"/> is necessary.
/// </remarks>
private static bool TryParseFromUri(string text, bool allowNamedValues, bool allowNull, out KeyInstance instance)
{
Debug.Assert(text != null, "text != null");
Dictionary<string, object> namedValues = null;
List<object> positionalValues = null;
ExpressionLexer lexer = new ExpressionLexer(text);
Token currentToken = lexer.CurrentToken;
if (currentToken.Id == TokenId.End)
{
instance = Empty;
return true;
}
instance = null;
do
{
if (currentToken.Id == TokenId.Identifier && allowNamedValues)
{
// Name-value pair.
if (positionalValues != null)
{
// We cannot mix named and non-named values.
return false;
}
string identifier = lexer.CurrentToken.GetIdentifier();
lexer.NextToken();
if (lexer.CurrentToken.Id != TokenId.Equal)
{
return false;
}
lexer.NextToken();
if (!lexer.CurrentToken.IsKeyValueToken)
{
return false;
}
string namedValue = lexer.CurrentToken.Text;
WebUtil.CreateIfNull(ref namedValues);
if (namedValues.ContainsKey(identifier))
{
// Duplicate name.
return false;
}
namedValues.Add(identifier, namedValue);
}
else if (currentToken.IsKeyValueToken || (allowNull && currentToken.Id == TokenId.NullLiteral))
{
// Positional value.
if (namedValues != null)
{
// We cannot mix named and non-named values.
return false;
}
WebUtil.CreateIfNull(ref positionalValues);
positionalValues.Add(lexer.CurrentToken.Text);
}
else
{
return false;
}
// Read the next token. We should be at the end, or find
// we have a comma followed by something.
lexer.NextToken();
currentToken = lexer.CurrentToken;
if (currentToken.Id == TokenId.Comma)
{
lexer.NextToken();
currentToken = lexer.CurrentToken;
if (currentToken.Id == TokenId.End)
{
// Trailing comma.
return false;
}
}
}
while (currentToken.Id != TokenId.End);
instance = new KeyInstance(namedValues, positionalValues);
return true;
}
/// <summary>Initializes a new <see cref="ExpressionParser"/>.</summary>
/// <param name="service">Service with data and configuration.</param>
/// <param name="setForIt">Resource set for "it" contextual variable</param>
/// <param name="typeForIt">Type for "it" contextual variable</param>
/// <param name="parameterForIt">Parameters for the current "it" context.</param>
/// <param name="expression">Expression to parse.</param>
internal ExpressionParser(IDataService service, ResourceSetWrapper setForIt, ResourceType typeForIt, ParameterExpression parameterForIt, string expression)
{
Debug.Assert(service != null, "service != null");
// For Open types, we could potentially have typeForIt parameter set to null value,
// However, we have decided not support ordering on Open properties which also implies
// that we can not have entity typed properties on Open types
Debug.Assert(typeForIt != null, "typeForIt != null");
Debug.Assert(expression != null, "expression != null");
Debug.Assert(parameterForIt != null, "parameterForIt != null");
this.service = service;
this.provider = service.Provider;
this.nullPropagationRequired = this.provider.NullPropagationRequired;
this.literals = new Dictionary<Expression, string>(ReferenceEqualityComparer<Expression>.Instance);
this.setForIt = setForIt;
this.typeForIt = typeForIt;
this.it = parameterForIt;
this.lexer = new ExpressionLexer(expression);
}
/// <summary>Parse one of the literals of skip token.</summary>
/// <param name="literal">Input literal.</param>
/// <returns>Object resulting from conversion of literal.</returns>
internal object ParseSkipTokenLiteral(String literal)
{
ExpressionLexer l = new ExpressionLexer(literal);
Expression e = this.ParsePrimaryStart(l);
if (e.NodeType != ExpressionType.Constant)
{
throw new InvalidOperationException(Strings.RequsetQueryParser_ExpectingLiteralInSkipToken(literal));
}
return ((ConstantExpression)e).Value;
}
/// <summary>Handles the start of primary expressions.</summary>
/// <param name="l">Lexer to use for reading tokens</param>
/// <returns>The parsed expression.</returns>
private Expression ParsePrimaryStart(ExpressionLexer l)
{
switch (l.CurrentToken.Id)
{
case TokenId.BooleanLiteral:
return this.ParseTypedLiteral(typeof(bool), XmlConstants.EdmBooleanTypeName, l);
case TokenId.DateTimeLiteral:
return this.ParseTypedLiteral(typeof(DateTime), XmlConstants.EdmDateTimeTypeName, l);
case TokenId.DecimalLiteral:
return this.ParseTypedLiteral(typeof(decimal), XmlConstants.EdmDecimalTypeName, l);
case TokenId.NullLiteral:
return ExpressionParser.ParseNullLiteral(l);
case TokenId.Identifier:
Debug.Assert(Object.ReferenceEquals(this.lexer, l), "Lexer should be the member lexer");
return this.ParseIdentifier();
case TokenId.StringLiteral:
return this.ParseTypedLiteral(typeof(string), XmlConstants.EdmStringTypeName, l);
case TokenId.Int64Literal:
return this.ParseTypedLiteral(typeof(Int64), XmlConstants.EdmInt64TypeName, l);
case TokenId.IntegerLiteral:
return this.ParseTypedLiteral(typeof(Int32), XmlConstants.EdmInt32TypeName, l);
case TokenId.DoubleLiteral:
return this.ParseTypedLiteral(typeof(double), XmlConstants.EdmDoubleTypeName, l);
case TokenId.SingleLiteral:
return this.ParseTypedLiteral(typeof(Single), XmlConstants.EdmSingleTypeName, l);
case TokenId.GuidLiteral:
return this.ParseTypedLiteral(typeof(Guid), XmlConstants.EdmGuidTypeName, l);
case TokenId.BinaryLiteral:
return this.ParseTypedLiteral(typeof(byte[]), XmlConstants.EdmBinaryTypeName, l);
case TokenId.OpenParen:
Debug.Assert(Object.ReferenceEquals(this.lexer, l), "Lexer should be the member lexer");
return this.ParseParenExpression();
default:
throw ParseError(Strings.RequestQueryParser_ExpressionExpected(l.CurrentToken.Position));
}
}
/// <summary>Handles typed literals.</summary>
/// <param name="targetType">Expected type to be parsed.</param>
/// <param name="targetTypeName">Expected type name.</param>
/// <param name="l">Lexer to use for reading tokens</param>
/// <returns>The constants expression produced by building the given literal.</returns>
private Expression ParseTypedLiteral(Type targetType, string targetTypeName, ExpressionLexer l)
{
object targetValue;
if (!WebConvert.TryKeyStringToPrimitive(l.CurrentToken.Text, targetType, out targetValue))
{
string message = Strings.RequestQueryParser_UnrecognizedLiteral(targetTypeName, l.CurrentToken.Text, l.CurrentToken.Position);
throw ParseError(message);
}
Expression result = this.CreateLiteral(targetValue, l.CurrentToken.Text);
l.NextToken();
return result;
}
/// <summary>
/// Generates a comparison expression which can handle NULL values for any type.
/// NULL is always treated as the smallest possible value.
/// So for example for strings NULL is smaller than any non-NULL string.
/// For now only GreaterThan and LessThan operators are supported by this method.
/// </summary>
/// <param name="left">Left hand side expression</param>
/// <param name="rightLiteral">Literal for the right hand side</param>
/// <param name="op">gt or lt operator token</param>
/// <returns>Resulting comparison expression (has a Boolean value)</returns>
private Expression GenerateNullAwareComparison(Expression left, String rightLiteral, Token op)
{
Debug.Assert(
op.Text == ExpressionConstants.KeywordGreaterThan || op.Text == ExpressionConstants.KeywordLessThan,
"Only GreaterThan or LessThan operators are supported by the GenerateNullAwateComparison method for now.");
ExpressionLexer l = new ExpressionLexer(rightLiteral);
Expression right = this.ParsePrimaryStart(l);
if (WebUtil.TypeAllowsNull(left.Type))
{
if (!WebUtil.TypeAllowsNull(right.Type))
{
right = Expression.Convert(right, typeof(Nullable<>).MakeGenericType(right.Type));
}
}
else if (WebUtil.TypeAllowsNull(right.Type))
{
left = Expression.Convert(left, typeof(Nullable<>).MakeGenericType(left.Type));
}
else
{
// Can't perform NULL aware comparison on this type. Just let the normal
// comparison deal with it. Since the type doesn't allow NULL one should
// never appear, so normal comparison is just fine.
return this.GenerateComparisonExpression(left, right, op);
}
switch (op.Text)
{
case ExpressionConstants.KeywordGreaterThan:
// (left != null) && ((right == null) || Compare(left, right) > 0)
if (left == WebUtil.NullLiteral)
{
return Expression.Constant(false, typeof(bool));
}
else if (right == WebUtil.NullLiteral)
{
return GenerateNotEqual(left, Expression.Constant(null, left.Type));
}
else
{
return GenerateLogicalAnd(
GenerateNotEqual(left, Expression.Constant(null, left.Type)),
GenerateLogicalOr(
GenerateEqual(right, Expression.Constant(null, right.Type)),
this.GenerateComparisonExpression(left, right, op)));
}
case ExpressionConstants.KeywordLessThan:
// (right != null) && ((left == null) || Compare(left, right) < 0)
if (right == WebUtil.NullLiteral)
{
return Expression.Constant(false, typeof(bool));
}
else if (left == WebUtil.NullLiteral)
{
return GenerateNotEqual(right, Expression.Constant(null, right.Type));
}
else
{
return GenerateLogicalAnd(
GenerateNotEqual(right, Expression.Constant(null, left.Type)),
GenerateLogicalOr(
GenerateEqual(left, Expression.Constant(null, right.Type)),
this.GenerateComparisonExpression(left, right, op)));
}
default:
// For now only < and > are supported as we use this only from $skiptoken
throw ParseError(
Strings.RequestQueryParser_NullOperatorUnsupported(op.Text, op.Position, this.lexer.ExpressionText));
}
}
/// <summary>
/// Generates a comparison expression given a left hand side expression and literal for right hand side
/// </summary>
/// <param name="left">Left hand side experssions</param>
/// <param name="rightLiteral">Literal for right hand side</param>
/// <param name="op">gt, eq or lt operator token</param>
/// <returns>Resulting comparison expression</returns>
private Expression GenerateComparison(Expression left, String rightLiteral, Token op)
{
ExpressionLexer l = new ExpressionLexer(rightLiteral);
return this.GenerateComparisonExpression(left, this.ParsePrimaryStart(l), op);
}
/// <summary>Handles 'null' literals.</summary>
/// <param name="l">Lexer to use for reading tokens</param>
/// <returns>The parsed expression.</returns>
private static Expression ParseNullLiteral(ExpressionLexer l)
{
Debug.Assert(l.CurrentToken.Id == TokenId.NullLiteral, "l.CurrentToken.Id == TokenId.NullLiteral");
l.NextToken();
return WebUtil.NullLiteral;
}
private static List<List<string>> ReadExpandOrSelect(string value, bool select, IDataService dataService)
{
List<List<string>> list = new List<List<string>>();
List<string> list2 = null;
ExpressionLexer lexer = new ExpressionLexer(value);
while (lexer.CurrentToken.Id != TokenId.End)
{
string text;
bool flag = false;
if (select && (lexer.CurrentToken.Id == TokenId.Star))
{
text = lexer.CurrentToken.Text;
lexer.NextToken();
flag = true;
}
else if (select)
{
bool flag2;
text = lexer.ReadDottedIdentifier(true);
if (dataService.Provider.GetNameFromContainerQualifiedName(text, out flag2) == "*")
{
flag = true;
}
}
else
{
text = lexer.ReadDottedIdentifier(false);
}
if (list2 == null)
{
list2 = new List<string> {
};
}
list2.Add(text);
TokenId id = lexer.CurrentToken.Id;
if (id != TokenId.End)
{
if (flag || (id != TokenId.Slash))
{
lexer.ValidateToken(TokenId.Comma);
list2 = null;
}
lexer.NextToken();
}
}
return list;
}
private static bool TryParseFromUri(string text, bool allowNamedValues, bool allowNull, out KeyInstance instance)
{
Dictionary<string, object> dictionary = null;
List<object> list = null;
ExpressionLexer lexer = new ExpressionLexer(text);
Token currentToken = lexer.CurrentToken;
if (currentToken.Id == TokenId.End)
{
instance = Empty;
return true;
}
instance = null;
do
{
if ((currentToken.Id == TokenId.Identifier) && allowNamedValues)
{
if (list != null)
{
return false;
}
string identifier = lexer.CurrentToken.GetIdentifier();
lexer.NextToken();
if (lexer.CurrentToken.Id != TokenId.Equal)
{
return false;
}
lexer.NextToken();
if (!lexer.CurrentToken.IsKeyValueToken)
{
return false;
}
string str2 = lexer.CurrentToken.Text;
WebUtil.CreateIfNull<Dictionary<string, object>>(ref dictionary);
if (dictionary.ContainsKey(identifier))
{
return false;
}
dictionary.Add(identifier, str2);
}
else
{
if (!currentToken.IsKeyValueToken && (!allowNull || (currentToken.Id != TokenId.NullLiteral)))
{
return false;
}
if (dictionary != null)
{
return false;
}
WebUtil.CreateIfNull<List<object>>(ref list);
list.Add(lexer.CurrentToken.Text);
}
lexer.NextToken();
currentToken = lexer.CurrentToken;
if (currentToken.Id == TokenId.Comma)
{
lexer.NextToken();
currentToken = lexer.CurrentToken;
if (currentToken.Id == TokenId.End)
{
return false;
}
}
}
while (currentToken.Id != TokenId.End);
instance = new KeyInstance(dictionary, list);
return true;
}
