/// <summary>
/// Tries to evaluate the given expression in the context of
/// the given environment.
/// </summary>
/// <param name="env">Environment in which to evaluate the
/// expression.</param>
/// <param name="value">On success, receives the evaluation
/// result.</param>
/// <returns>true on success; false otherwise.</returns>
public override bool TryEvaluate(ExpressionEnvironment env, out string value)
{
if (env == null)
{
throw new ArgumentNullException(nameof(env));
}
if (!Operand.TryEvaluate(env, out string operand))
{
value = null;
return(false);
}
switch (Operator)
{
case Operator.ConvertToUpperCase:
value = operand.ToUpper();
return(true);
case Operator.ConvertToLowerCase:
value = operand.ToLower();
return(true);
case Operator.Unspecified:
default:
throw new InternalInvariantBrokenException("Unknown operator");
}
}
/// <summary>
/// Tries to evaluate the given expression in the context of
/// the given environment.
/// </summary>
/// <param name="env">Environment in which to evaluate the
/// expression.</param>
/// <param name="value">On success, receives the evaluation
/// result.</param>
/// <returns>true on success; false otherwise.</returns>
public override bool TryEvaluate(ExpressionEnvironment env, out string value)
{
if (env == null)
{
throw new ArgumentNullException(nameof(env));
}
if (!Condition.TryEvaluate(env, out string condition) ||
!ThenExpression.TryEvaluate(env, out string thenValue))
{
value = null;
return(false);
}
string elseValue = string.Empty;
if (ElseExpression.HasValue &&
!ElseExpression.Value.TryEvaluate(env, out elseValue))
{
value = null;
return(false);
}
var conditionValue = !string.IsNullOrEmpty(condition);
value = conditionValue ? thenValue : elseValue;
return(true);
}
/// <summary>
/// Try to expand the given string value in the context of the
/// provided environment.
/// </summary>
/// <param name="env">Environment for context.</param>
/// <param name="value">Value to expand.</param>
/// <param name="result">On success, receives the expanded result.</param>
/// <returns>true on success; false otherwise.</returns>
public static bool TryExpand(ExpressionEnvironment env, string value, out string result)
{
var builder = new StringBuilder();
for (var i = 0; i < value.Length;)
{
var exprStartIndex = value.IndexOf(ExprStartChar, i);
if (exprStartIndex < 0)
{
builder.Append(value.Substring(i, value.Length - i));
break;
}
if (exprStartIndex > i)
{
builder.Append(value.Substring(i, exprStartIndex - i));
}
if (exprStartIndex + 1 >= value.Length)
{
result = null;
return(false);
}
var exprEndIndex = value.IndexOf(ExprEndChar, exprStartIndex + 1);
if (exprEndIndex < 0)
{
result = null;
return(false);
}
if (exprEndIndex - exprStartIndex <= 1)
{
result = null;
return(false);
}
var exprString = value.Substring(exprStartIndex + 1, exprEndIndex - exprStartIndex - 1);
if (!ExpressionParser.TryParse(exprString, out Expression expr))
{
result = null;
return(false);
}
if (!expr.TryEvaluate(env, out string evalutedExpr))
{
result = null;
return(false);
}
builder.Append(evalutedExpr);
i = exprEndIndex + 1;
}
result = builder.ToString();
return(true);
}
/// <summary>
/// Tries to evaluate the given expression in the context of
/// the given environment.
/// </summary>
/// <param name="env">Environment in which to evaluate the
/// expression.</param>
/// <param name="value">On success, receives the evaluation
/// result.</param>
/// <returns>true on success; false otherwise.</returns>
public override bool TryEvaluate(ExpressionEnvironment env, out string value)
{
if (env == null)
{
throw new ArgumentNullException(nameof(env));
}
value = Value;
return(true);
}
/// <summary>
/// Tries to evaluate the given expression in the context of
/// the given environment.
/// </summary>
/// <param name="env">Environment in which to evaluate the
/// expression.</param>
/// <param name="value">On success, receives the evaluation
/// result.</param>
/// <returns>true on success; false otherwise.</returns>
public override bool TryEvaluate(ExpressionEnvironment env, out string value)
{
if (env == null)
{
throw new ArgumentNullException(nameof(env));
}
if (env.TryGetVariable(VariableName, out value))
{
return(true);
}
value = string.Empty;
return(true);
}
/// <summary>
/// Tries to evaluate the given expression in the context of
/// the given environment.
/// </summary>
/// <param name="env">Environment in which to evaluate the
/// expression.</param>
/// <param name="value">On success, receives the evaluation
/// result.</param>
/// <returns>true on success; false otherwise.</returns>
public override bool TryEvaluate(ExpressionEnvironment env, out string value)
{
if (env == null)
{
throw new ArgumentNullException(nameof(env));
}
if (!Left.TryEvaluate(env, out string left) ||
!Right.TryEvaluate(env, out string right))
{
value = null;
return(false);
}
value = left + right;
return(true);
}
/// <summary> /// Tries to evaluate the given expression in the context of /// the given environment. /// </summary> /// <param name="env">Environment in which to evaluate the /// expression.</param> /// <param name="value">On success, receives the evaluation /// result.</param> /// <returns>true on success; false otherwise.</returns> public override bool TryEvaluate(ExpressionEnvironment env, out string value) => InnerExpression.TryEvaluate(env, out value);