/// <summary>
/// evaluate expression
/// </summary>
/// <param name="args"></param>
/// <param name="result"></param>
/// <returns></returns>
private bool eval(string args, out string result)
{
int i = 0;
int k = 0;
char[] buf = new char[5000];
while (k < args.Length)
{
if (k < args.Length - 1 && ((args[k] == '{' && args[k + 1] == '{') || (args[k] == '}' && args[k + 1] == '}')))
{
buf[i++] = args[k++];
}
else if (args[k] == '{')
{
k++;
int index = 0; //index of expr[]
char[] expr = new char[4000];
while (k < args.Length && args[k] != '}')
{
expr[index++] = args[k];
k++;
}
if (k == args.Length)
{
cerr.WriteLine("Unclosed expression character }");
result = string.Empty;
return(false);
}
string code = new string(expr, 0, index);
if (IsFormatString(code))
{
buf[i++] = '{';
foreach (char ch in code)
{
buf[i++] = ch;
}
buf[i++] = '}';
}
else
{
string text = string.Empty;
try
{
VAL val = Script.Evaluate(code, Context.DS);
text = val.ToSimpleString();
}
catch (Exception ex)
{
cerr.WriteLine($"error in {code}, {ex.Message}");
}
foreach (char ch in text)
{
buf[i++] = ch;
}
}
}
else if (args[k] == '}')
{
cerr.WriteLine("Unclosed expression character }");
result = string.Empty;
return(false);
}
else
{
buf[i++] = args[k];
}
k++;
}
result = new string(buf, 0, i);
return(true);
}