Fixed expressions to be able to do math with nested expressions.

Operand.cpp

@@ -7,8 +7,22 @@ namespace jet {
 
    Operand::Operand(coreutils::ZString &in) {
 
+      doubleValue = 0;
+      
       in.skipWhitespace();
-      std::cout << "op: [" << in.unparsed() << "]" << std::endl;
+
+//      std::cout << "op: [" << in.unparsed() << "]" << std::endl;
+
+      if(in.ifNext("(")) {
+//	 std::cout << "(" << in.unparsed() << std::endl;
+	 Operand op(in);
+	 string = op.string;
+	 doubleValue = op.doubleValue;
+	 if(!in.ifNext(")")) 
+	   throw coreutils::Exception("expected ) in expression.");	      
+//	 std::cout << ")" << in.unparsed() << std::endl;	 
+      } 
+      
       if(in.ifNext("SUBSTRING")) {
 	 if(!in.ifNext("("))
 	   throw coreutils::Exception("Expecting ( for SUBSTRING parameters.");
@@ -44,21 +58,66 @@ namespace jet {
       } else if(in.ifNext("true")) {
 	 boolean = true;
 	 string = "true";
-	 return;
       } else if(in.ifNext("false")) {
 	 boolean = false;
 	 string = "false";
-	 return;
       } else if(in.startsWithNumber()) {
 	 doubleValue = in.asDouble();
 	 string = std::format("{}", doubleValue);
-         return;
+	 isNumber = true;
       } else if(in.ifNext("'")) {
 	 string = in.getTokenExclude("'");
 	 in.ifNext("'");
+	 isNumber = false;
+      }
+
+      in.skipWhitespace();     
+      
+      if(in.ifNext("+")) {
+	 if(isNumber) {	      
+	    Operand op(in);
+	    if(op.isNumber) {
+	       doubleValue += op.doubleValue;
+	       string = std::format("{}", doubleValue);	       
+	    } else
+	      throw coreutils::Exception("operand is not a number.");
+	 } else
+	   throw coreutils::Exception("operand is not a number.");	 
+      } else if(in.ifNext("-")) {
+	 if(isNumber) {	      
+	    Operand op(in);
+	    if(op.isNumber) {
+	       doubleValue -= op.doubleValue;
+	       string = std::format("{}", doubleValue);	       
+	    } else
+	      throw coreutils::Exception("operand is not a number.");
+	 } else
+	   throw coreutils::Exception("operand is not a number.");	 
+      } else if(in.ifNext("*")) {
+	 if(isNumber) {	      
+	    Operand op(in);
+	    if(op.isNumber) {
+	       doubleValue *= op.doubleValue;
+	       string = std::format("{}", doubleValue);	       
+	    } else
+	      throw coreutils::Exception("operand is not a number.");
+	 } else
+	   throw coreutils::Exception("operand is not a number.");	 
+      } else if(in.ifNext("/")) {
+	 if(isNumber) {	      
+	    Operand op(in);
+	    if(op.isNumber) {
+	       doubleValue /= op.doubleValue;
+	       string = std::format("{}", doubleValue);	       
+	    } else
+	      throw coreutils::Exception("operand is not a number.");
+	 } else
+	   throw coreutils::Exception("operand is not a number.");	 
+      } else {
+//	 std::cout << ">" << string << std::endl;
 	 return;
       }
-	 
+     
    }
    
 }