improved syntax checking on expr. Laid foundation for expr function.

Operand.cpp

@@ -53,7 +53,16 @@ namespace jet {
 	 } else
 	   throw coreutils::Exception("Expecting ) at end of LEFT expression.");	 
       } else if(in.ifNextIgnoreCase("EXPR")) {
-	 
+	 if(!in.ifNext("("))
+	   throw coreutils::Exception("Expecting ( for LEFT parameters.");
+	 Operand parm1(in, global, lvariables);
+	 if(in.ifNext(")")) {
+	    Operand op(in, global, lvariables);
+	    string = op.string;
+	    isNumber = op.isNumber;
+	    boolean = op.boolean;	    
+	 } else
+	   throw coreutils::Exception("Expecting ) at end of EXPR expression.");	 	 
       } else if(in.ifNextIgnoreCase("RIGHT")) {
 	 
       } else if(in.ifNextIgnoreCase("TRIM")) {
@@ -90,7 +99,8 @@ namespace jet {
 	 string = in.getTokenExclude("'");
 	 in.ifNext("'");
 	 isNumber = false;
-      }
+      } else
+	throw coreutils::Exception("operand is not valid.");
 
       in.skipWhitespace();
       
@@ -284,7 +294,6 @@ namespace jet {
 	   throw coreutils::Exception("operand is not a number.");	 
       } else 
 	return;
-           
    }
    
 }