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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
using System;
using System.Text;
using System.Globalization;
namespace Apache.NMS.Selector
{
/// <summary>
/// Represents a constant expression.
/// </summary>
public class ConstantExpression : IExpression
{
private object value;
public object Value
{
get { return value; }
}
public ConstantExpression(object value)
{
this.value = value;
}
public static ConstantExpression CreateFromDecimal(string text)
{
// Long integer specified ?
object value;
if(text.EndsWith("l") || text.EndsWith("L"))
{
text = text.Substring(0, text.Length - 1);
value = Int64.Parse(text, CultureInfo.InvariantCulture);
}
else
{
long lvalue = Int64.Parse(text, CultureInfo.InvariantCulture);
if(lvalue >= Int32.MinValue && lvalue <= Int32.MaxValue)
{
value = (int)lvalue;
}
else
{
value = lvalue;
}
}
return new ConstantExpression(value);
}
public static ConstantExpression CreateFromHex(string text)
{
long lvalue = Convert.ToInt64(text.Substring(2), 16);
object value;
if(lvalue >= Int32.MinValue && lvalue <= Int32.MaxValue)
{
value = (int)lvalue;
}
else
{
value = lvalue;
}
return new ConstantExpression(value);
}
public static ConstantExpression CreateFromOctal(string text)
{
long lvalue = Convert.ToInt64(text, 8);
object value;
if(lvalue >= Int32.MinValue && lvalue <= Int32.MaxValue)
{
value = (int)lvalue;
}
else
{
value = lvalue;
}
return new ConstantExpression(value);
}
public static ConstantExpression CreateFloat(string text)
{
double value = Double.Parse(text, CultureInfo.InvariantCulture);
return new ConstantExpression(value);
}
public object Evaluate(MessageEvaluationContext message)
{
return value;
}
public override string ToString()
{
if(value == null)
{
return "NULL";
}
if(value is bool)
{
return (bool)value ? "TRUE" : "FALSE";
}
if(value is string)
{
return EncodeString((string)value);
}
return value.ToString();
}
public override int GetHashCode()
{
return (value == null ? 0 : value.GetHashCode());
}
/// <summary>
/// Encodes the value of string so that it looks like it would look like
/// when it was provided in a selector.
/// </summary>
/// <param name="s">String to be encoded.</param>
/// <return>Encoded string.</return>
public static string EncodeString(string s)
{
StringBuilder b = new StringBuilder();
b.Append('\'');
for(int c = 0; c < s.Length; c++)
{
char ch = s[c];
if(ch == '\'')
{
b.Append(ch);
}
b.Append(ch);
}
b.Append('\'');
return b.ToString();
}
public static readonly BooleanConstantExpression NULL = new BooleanConstantExpression(null);
public static readonly BooleanConstantExpression TRUE = new BooleanConstantExpression(true);
public static readonly BooleanConstantExpression FALSE = new BooleanConstantExpression(false);
}
}