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ConditionRelationalExpression.cs
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ConditionRelationalExpression.cs
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//
// Copyright (c) 2004-2019 Jaroslaw Kowalski <jaak@jkowalski.net>, Kim Christensen, Julian Verdurmen
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// * Neither the name of Jaroslaw Kowalski nor the names of its
// contributors may be used to endorse or promote products derived from this
// software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE.
//
namespace NLog.Conditions
{
using System;
using System.Globalization;
using System.Collections.Generic;
using NLog.Common;
/// <summary>
/// Condition relational (<b>==</b>, <b>!=</b>, <b><</b>, <b><=</b>,
/// <b>></b> or <b>>=</b>) expression.
/// </summary>
internal sealed class ConditionRelationalExpression : ConditionExpression
{
/// <summary>
/// Initializes a new instance of the <see cref="ConditionRelationalExpression" /> class.
/// </summary>
/// <param name="leftExpression">The left expression.</param>
/// <param name="rightExpression">The right expression.</param>
/// <param name="relationalOperator">The relational operator.</param>
public ConditionRelationalExpression(ConditionExpression leftExpression, ConditionExpression rightExpression, ConditionRelationalOperator relationalOperator)
{
LeftExpression = leftExpression;
RightExpression = rightExpression;
RelationalOperator = relationalOperator;
}
/// <summary>
/// Gets the left expression.
/// </summary>
/// <value>The left expression.</value>
public ConditionExpression LeftExpression { get; private set; }
/// <summary>
/// Gets the right expression.
/// </summary>
/// <value>The right expression.</value>
public ConditionExpression RightExpression { get; private set; }
/// <summary>
/// Gets the relational operator.
/// </summary>
/// <value>The operator.</value>
public ConditionRelationalOperator RelationalOperator { get; private set; }
/// <summary>
/// Returns a string representation of the expression.
/// </summary>
/// <returns>
/// A <see cref="T:System.String"/> that represents the condition expression.
/// </returns>
public override string ToString()
{
return $"({LeftExpression} {GetOperatorString()} {RightExpression})";
}
/// <summary>
/// Evaluates the expression.
/// </summary>
/// <param name="context">Evaluation context.</param>
/// <returns>Expression result.</returns>
protected override object EvaluateNode(LogEventInfo context)
{
object v1 = LeftExpression.Evaluate(context);
object v2 = RightExpression.Evaluate(context);
return Compare(v1, v2, RelationalOperator);
}
/// <summary>
/// Compares the specified values using specified relational operator.
/// </summary>
/// <param name="leftValue">The first value.</param>
/// <param name="rightValue">The second value.</param>
/// <param name="relationalOperator">The relational operator.</param>
/// <returns>Result of the given relational operator.</returns>
private static object Compare(object leftValue, object rightValue, ConditionRelationalOperator relationalOperator)
{
#if !NETSTANDARD1_0
System.Collections.IComparer comparer = StringComparer.InvariantCulture;
#else
System.Collections.IComparer comparer = StringComparer.Ordinal;
#endif
PromoteTypes(ref leftValue, ref rightValue);
switch (relationalOperator)
{
case ConditionRelationalOperator.Equal:
return comparer.Compare(leftValue, rightValue) == 0;
case ConditionRelationalOperator.NotEqual:
return comparer.Compare(leftValue, rightValue) != 0;
case ConditionRelationalOperator.Greater:
return comparer.Compare(leftValue, rightValue) > 0;
case ConditionRelationalOperator.GreaterOrEqual:
return comparer.Compare(leftValue, rightValue) >= 0;
case ConditionRelationalOperator.LessOrEqual:
return comparer.Compare(leftValue, rightValue) <= 0;
case ConditionRelationalOperator.Less:
return comparer.Compare(leftValue, rightValue) < 0;
default:
throw new NotSupportedException($"Relational operator {relationalOperator} is not supported.");
}
}
/// <summary>
/// Promote values to the type needed for the comparision, e.g. parse a string to int.
/// </summary>
/// <param name="leftValue"></param>
/// <param name="rightValue"></param>
private static void PromoteTypes(ref object leftValue, ref object rightValue)
{
if (leftValue == null || rightValue == null)
{
return;
}
var leftType = leftValue.GetType();
var rightType = rightValue.GetType();
if (leftType == rightType)
{
return;
}
//types are not equal
var leftTypeOrder = GetOrder(leftType);
var rightTypeOrder = GetOrder(rightType);
if (leftTypeOrder < rightTypeOrder)
{
// first try promote right value with left type
if (TryPromoteTypes(ref rightValue, leftType, ref leftValue, rightType)) return;
}
else
{
// otherwise try promote leftValue with right type
if (TryPromoteTypes(ref leftValue, rightType, ref rightValue, leftType)) return;
}
throw new ConditionEvaluationException($"Cannot find common type for '{leftType.Name}' and '{rightType.Name}'.");
}
/// <summary>
/// Promotes <paramref name="val"/> to type
/// </summary>
/// <param name="val"></param>
/// <param name="type1"></param>
/// <returns>success?</returns>
private static bool TryPromoteType(ref object val, Type type1)
{
try
{
if (type1 == typeof(DateTime))
{
val = Convert.ToDateTime(val, CultureInfo.InvariantCulture);
return true;
}
if (type1 == typeof(double))
{
val = Convert.ToDouble(val, CultureInfo.InvariantCulture);
return true;
}
if (type1 == typeof(float))
{
val = Convert.ToSingle(val, CultureInfo.InvariantCulture);
return true;
}
if (type1 == typeof(decimal))
{
val = Convert.ToDecimal(val, CultureInfo.InvariantCulture);
return true;
}
if (type1 == typeof(long))
{
val = Convert.ToInt64(val, CultureInfo.InvariantCulture);
return true;
}
if (type1 == typeof(int))
{
val = Convert.ToInt32(val, CultureInfo.InvariantCulture);
return true;
}
if (type1 == typeof(bool))
{
val = Convert.ToBoolean(val, CultureInfo.InvariantCulture);
return true;
}
if (type1 == typeof(string))
{
val = Convert.ToString(val, CultureInfo.InvariantCulture);
InternalLogger.Debug("Using string comparision");
return true;
}
}
catch (Exception)
{
InternalLogger.Debug("conversion of {0} to {1} failed", val, type1.Name);
}
return false;
}
/// <summary>
/// Try to promote both values. First try to promote <paramref name="val1"/> to <paramref name="type1"/>,
/// when failed, try <paramref name="val2"/> to <paramref name="type2"/>.
/// </summary>
/// <returns></returns>
private static bool TryPromoteTypes(ref object val1, Type type1, ref object val2, Type type2)
{
return TryPromoteType(ref val1, type1) || TryPromoteType(ref val2, type2);
}
/// <summary>
/// Get the order for the type for comparision.
/// </summary>
/// <param name="type1"></param>
/// <returns>index, 0 to maxint. Lower is first</returns>
private static int GetOrder(Type type1)
{
int order;
var success = TypePromoteOrder.TryGetValue(type1, out order);
if (success)
{
return order;
}
//not found, try as last
return int.MaxValue;
}
/// <summary>
/// Dictionary from type to index. Lower index should be tested first.
/// </summary>
private static Dictionary<Type, int> TypePromoteOrder = BuildTypeOrderDictionary();
/// <summary>
/// Build the dictionary needed for the order of the types.
/// </summary>
/// <returns></returns>
private static Dictionary<Type, int> BuildTypeOrderDictionary()
{
var list = new List<Type>
{
typeof(DateTime),
typeof(double),
typeof(float),
typeof(decimal),
typeof(long),
typeof(int),
typeof(bool),
typeof(string),
};
var dict = new Dictionary<Type, int>(list.Count);
for (int i = 0; i < list.Count; i++)
{
dict.Add(list[i], i);
}
return dict;
}
/// <summary>
/// Get the string representing the current <see cref="ConditionRelationalOperator"/>
/// </summary>
/// <returns></returns>
private string GetOperatorString()
{
switch (RelationalOperator)
{
case ConditionRelationalOperator.Equal:
return "==";
case ConditionRelationalOperator.NotEqual:
return "!=";
case ConditionRelationalOperator.Greater:
return ">";
case ConditionRelationalOperator.Less:
return "<";
case ConditionRelationalOperator.GreaterOrEqual:
return ">=";
case ConditionRelationalOperator.LessOrEqual:
return "<=";
default:
throw new NotSupportedException($"Relational operator {RelationalOperator} is not supported.");
}
}
}
}