Started into the Expression and Operand obejcts.

Operand.cpp

@@ -1,15 +1,56 @@
 #include "Operand.h"
+#include "Exception.h"
 
 namespace jet {
 
    Operand::Operand(coreutils::ZString &in) {
 
+      in.skipWhitespace();
+
+      if(in.ifNext("SUBSTRING")) {
+	 if(!in.ifNext("("))
+	   throw coreutils::Exception("Expecting ( for SUBSTRING parameters.");
+	 Operand parm1(in);
+	 if(!in.ifNext(","))
+	   throw coreutils::Exception("Expecting , in SUBSTRING expression.");
+	 Operand parm2(in);
+	 if(in.ifNext(")")) {	      
+	    string = parm1.string.substring(parm2.string.asInteger());
+	 }
+	 else if(!in.ifNext(","))
+	   throw coreutils::Exception("Expecting , in SUBSTRING expression.");
+	 Operand parm3(in);
+	 if(in.ifNext(")")) {
+	    string = parm1.string.substring(parm2.string.asInteger(), parm3.string.asInteger());
+	 }
+	 else
+	   throw coreutils::Exception("Expecting ) at end of substring expression.");
+      }
+  
+      else if(in.ifNext("LEFT")) {
+	 
+      } else if(in.ifNext("RIGHT")) {
+	 
+      } else if(in.ifNext("TRIM")) {
+	 
+      } else if(in.ifNext("TOUPPER")) {
+	 
+      } else if(in.ifNext("TOLOWER")) {
+	 
+      } else if(in.ifNext("REVERSE")) {
+	 
+      } else if(in.ifNext("CONCAT")) {
+	 
+      }
+      
       if(in.ifNext("true")) {
 	 boolean = true;
+	 string = "true";
 	 return;
       }
       if(in.ifNext("false")) {
 	 boolean = false;
+	 string = "false";
 	 return;
       }