public static DbValue COMPARE(DbFunctionTools tools, DbFunctionArguments args)
{
string FunctionName = "COMPARE";
args.EnsureCount(FunctionName, 2);
int result;
DbType arg0type;
ByteSlice arg0 = args[0].Eval(out arg0type);
DbType arg1type;
ByteSlice arg1 = args[1].Eval(out arg1type);
if (Types.IsNullValue(arg0))
{
result = int.MaxValue;
return(tools.AllocValue(result));
}
if (Types.IsNullValue(arg1))
{
result = int.MinValue;
return(tools.AllocValue(result));
}
int i0 = 0, i1 = 0;
long l0 = 0, l1 = 0;
double d0 = 0, d1 = 0;
switch (arg0type.ID)
{
case DbTypeID.INT:
i0 = tools.GetInt(arg0);
break;
case DbTypeID.LONG:
l0 = tools.GetLong(arg0);
break;
case DbTypeID.DOUBLE:
d0 = tools.GetDouble(arg0);
break;
case DbTypeID.CHARS:
{
if (arg1type.ID != DbTypeID.CHARS && arg1type.ID != DbTypeID.DATETIME)
{
args.Expected(FunctionName, 0, "input CHAR(n) or DATETIME, got " + arg1type.Name.ToUpper());
return(null); // Doesn't reach here.
}
if (arg1type.ID == DbTypeID.CHARS)
{
for (int i = 1; ; i += 2)
{
bool b1end = (i + 2 > arg0.Length) || (arg0[i] == 0 && arg0[i + 1] == 0);
bool b2end = (i + 2 > arg1.Length) || (arg1[i] == 0 && arg1[i + 1] == 0);
if (b1end)
{
if (b2end)
{
result = 0;
break;
}
result = -1;
break;
}
else if (b2end)
{
result = 1;
break;
}
int diff = Types.UTF16BytesToLowerChar(arg0[i], arg0[i + 1])
- Types.UTF16BytesToLowerChar(arg1[i], arg1[i + 1]);
if (0 != diff)
{
char ch0 = Types.UTF16BytesToChar(arg0[i], arg0[i + 1]);
char ch1 = Types.UTF16BytesToChar(arg1[i], arg1[i + 1]);
if (!Char.IsLetter(ch0) || !Char.IsLetter(ch1))
{
result = ch0 - ch1;
}
result = diff;
break;
}
}
}
else
{
string sdt = tools.GetString(arg0).ToString();
DateTime dt0 = DateTime.Parse(sdt);
DateTime dt1 = tools.GetDateTime(arg1);
result = dt0.CompareTo(dt1);
}
return(tools.AllocValue(result));
}
break;
case DbTypeID.DATETIME:
{
if (arg1type.ID != DbTypeID.CHARS && arg1type.ID != DbTypeID.DATETIME)
{
args.Expected(FunctionName, 0, "input CHAR(n) or DATETIME, got " + arg1type.Name.ToUpper());
return(null); // Doesn't reach here.
}
if (arg1type.ID == DbTypeID.DATETIME)
{
DateTime dt0 = tools.GetDateTime(arg0);
DateTime dt1 = tools.GetDateTime(arg1);
result = dt0.CompareTo(dt1);
}
else
{
DateTime dt0 = tools.GetDateTime(arg0);
string sdt = tools.GetString(arg1).ToString();
DateTime dt1 = DateTime.Parse(sdt);
result = dt0.CompareTo(dt1);
}
return(tools.AllocValue(result));
}
break;
default:
args.Expected(FunctionName, 0, "input INT, LONG or DOUBLE, got1 " + arg0type.Name.ToUpper());
return(null); // Doesn't reach here.
}
switch (arg1type.ID)
{
case DbTypeID.INT:
i1 = tools.GetInt(arg1);
break;
case DbTypeID.LONG:
l1 = tools.GetLong(arg1);
break;
case DbTypeID.DOUBLE:
d1 = tools.GetDouble(arg1);
break;
default:
args.Expected(FunctionName, 0, "input INT, LONG or DOUBLE, got2 " + arg1type.Name.ToUpper());
return(null); // Doesn't reach here.
}
switch (arg0type.ID)
{
case DbTypeID.INT:
switch (arg1type.ID)
{
case DbTypeID.INT:
result = i0.CompareTo(i1);
break;
case DbTypeID.LONG:
result = ((long)i0).CompareTo(l1);
break;
case DbTypeID.DOUBLE:
result = ((double)i0).CompareTo(d1);
break;
default:
return(null); // Should never happen.
}
break;
case DbTypeID.LONG:
switch (arg1type.ID)
{
case DbTypeID.INT:
result = l0.CompareTo((long)i1);
break;
case DbTypeID.LONG:
result = l0.CompareTo(l1);
break;
case DbTypeID.DOUBLE:
result = ((double)l0).CompareTo(d1);
break;
default:
return(null); // Should never happen.
}
break;
case DbTypeID.DOUBLE:
switch (arg1type.ID)
{
case DbTypeID.INT:
result = d0.CompareTo((double)i1);
break;
case DbTypeID.LONG:
result = d0.CompareTo((double)l1);
break;
case DbTypeID.DOUBLE:
result = d0.CompareTo(d1);
break;
default:
return(null); // Should never happen.
}
break;
default:
return(null); // Should never happen.
}
return(tools.AllocValue(result));
}
