/// <summary>
/// Method to convert the identifier from string to <see cref="Expression"/>.
/// </summary>
/// <param name="context">The context of evaluation</param>
/// <param name="message">The message to convert</param>
/// <param name="data">Result expression data</param>
/// <returns>The result expression</returns>
public override Expression GetExpression(EvaluationContext context, string message, ref ExpressionData data)
{
string valObj = message.ToLowerInvariant();
if (valObj == "true")
{
return(Expression.Constant(true, typeof(bool)));
}
if (valObj == "false")
{
return(Expression.Constant(false, typeof(bool)));
}
string[] me = message.Split(new[] { '.' }, 2);
// parameter first
Expression exp = context.ParamListExpressions.FirstOrDefault(p => p.Name == me[0]);
Type t = null;
string rest = null;
// found the parameter
if (exp != null)
{
rest = me.Length > 1 ? me[1] : null;
if (string.IsNullOrEmpty(rest))
{
return(exp);
}
}
// check the defined type aliases
if (exp == null && context.TypeAliases.ContainsKey(me[0]))
{
t = context.TypeAliases[me[0]];
rest = me.Length > 1 ? me[1] : null;
//MemberInfo[] mi = t.GetMember(me[1]);
//return Expression.MakeMemberAccess(null, me[0]);
}
if (exp == null && t == null)
{
Assembly[] asm = Reflect.GetAssemblies();
// find class in included namespaces
me = message.Split(new[] { '.' });
foreach (var ns in new[] { string.Empty }.Union(context.Namespaces))
{
// search nested namespaces
for (int i = 0; i < me.Length && t == null; i++)
{
Type t0 = asm.Select(o => o.GetType($"{ns}.{string.Join(".", me.Take(i + 1).ToArray())}", false))
.FirstOrDefault(o => o != null);
if (t0 != null)
{
t = t0;
rest = string.Join(".", me.Skip(i + 1).ToArray());
}
}
if (t != null)
{
break;
}
}
}
if (exp == null && t == null)
{
throw new EvaluationException($"Unable to evaluate {message}");
}
if (string.IsNullOrEmpty(rest))
{
CastTo(t, ref data);
return(null);
}
else
{
me = rest.Split(new[] { '.' });
Type t2;
foreach (string m in me)
{
t = t ?? exp?.Type;
if (exp == null || t == null)
{
MemberInfo[] mi = t.GetMember(m);
if (me.Length > 0)
{
exp = Expression.MakeMemberAccess(exp, mi[0]);
t = t2 = exp.Type;
continue;
}
}
#if NETSTANDARD
t2 = t.GetTypeInfo().GetProperty(m)?.PropertyType;
#else
t2 = t.GetProperty(m)?.PropertyType;
#endif
if (t == null)
{
throw new EvaluationException($"Unable to find property {m} on type {t.Name}.");
}
#if NETSTANDARD
if (exp.Type.GetTypeInfo().IsAssignableFrom((Type)null))
#else
if (exp.Type.IsAssignableFrom((Type)null))
#endif
{
// checked
exp = Expression.Coalesce(
Expression.PropertyOrField(exp, m),
Expression.Constant(null, exp.Type));
}
else
{
// unchecked
exp = Expression.PropertyOrField(
exp,
m);
}
}
}
if (exp != null)
{
return(exp);
}
if (t == null)
{
throw new EvaluationException($"Unable to evaluate {rest} on type {t.FullName}");
}
return(null);
}