Translator – Table Entry Expression Information

There will be an expression information structure for holding the expression related data for operators and internal functions (data type, unary code, number of operands, operand data types, number of associated codes and associated codes). The plan was to use the new operator along with the constructor of the expression information structure within the table entries like this:

{value, value, new ExprInfo(value, value, …), value, …},

The constructor would have a variable number of argument depending on the requirements of the operator or internal function. However, in practice this did not work. While variable arguments can be used in constructors, the actual arguments in the “...” can not be enumerations. So instead, the expression information structure along with the operand data type and associated code arrays will be defined outside of the table entries like this:

DataType Op_OperandDataType[2] = {Double_DataType, Double_DataType};
Code Op_AssocCode[1] = {OpInt_Code};
ExprInfo Op_ExprInfo(Double_DataType, Null_Code, 2, Op_OperandDataType,
  1, Op_AssocCode);

If there are no operands (no argument internal functions only) or associated codes, then there will be no need to define these arrays. The constructor will be defined with default arguments that will set the pointers to the arrays to NULL. For the expression information above, the table entry will look like this:

{value, value, &Op_ExprInfo, value, …},

The table access functions will be modified to get the data using the expression information structure pointer of the table entry instead of direct members of the table entry. Because of the nature of C++, none of the code that uses the access functions need to be modified, with one caveat. The match code function assumed there were two associated codes and stopped its loop when a Null code was found. This function will be changed to get the number of associated codes (a new access function) and use that value for the loop. Fortunately this is a very minor change.

Now there is a lot of editing to modify the table entries for the new expression information structures and then on to implementing data handling for the assignment operators...