How do I manipulate this dynamic vector for fold operations

I am working with flex/bison to create an interpreter for a class. The problem that I am encountering seems to be related to using/converting a dynamic vector. I am trying to create a function to evaluate fold operations, but I hit a roadblock. The list type is specified as a dynamic vector to allow for any number of arguments to be passed to it.

%union { CharPtr iden; Operators oper; double value; vector<double>* list; } 

%type <list> list expressions list_choice 

The bison direction is to pass the direction of the fold, the operator for the fold, and the dynamic vector to the function evaulateFold().

FOLD direction operator list_choice ENDFOLD SEMICOLON {$$ = evaluateFold($2, $3, $4);} 

Once I get it to this point, I cannot do anything with the dynamic array. I tried to copy it to a regular array using for loops but it says that there is no start point reference for the dynamic array this range-based 'for' statement requires a suitable "begin" function and none was foundC/C++(2291). I tried passing the array to evaluateFold() using ,const std::vector<double>& values, but then it says that there is no way to convert std::vector<double>* to std::vector<double>&``no suitable constructor exists to convert from "std::vector<double, std::allocator<double>> *" to "std::vector<double, std::allocator<double>> &"C/C++(415). How am I supposed to be able to use this array for the function?

double evaluateFold(Operators direction, Operators action, vector<double>* values){ double result = 0; switch(direction){ case LFOLD: switch(action){ case SUBTRACT: subFromLeft(values); for (auto i : values) cout << i << endl; break; } case RFOLD: switch(action){ case SUBTRACT: for (auto i : values) cout << i << endl; break; } break; } return result; } 

I was trying to use a variadic function for the actual fold function, but I cannot even get the vector to allow me to use it.

template <typename ...Args> auto subFromLeft(Args ...args) { return (... - args); } 

I did just pass the dynamic array all the way using vector<double>* values, but then it said there was no way to resolve vector<double>* values to a double, which would be the result I need from the operation.

Here is another way I tried to complete the fold operation but again, it would not let me use the const std::vector<double>& values reference because it said there is no viable conversion.

double subFromLeft(const std::vector<double>& values) { if (values.empty()) return 0; // Handle empty vector double result = values[0]; for (size_t i = 1; i < values.size(); i++) { result -= values[i]; } return result; } 

If anybody could help me resolve this, or at least point me in the right direction, that would be awesome. It is more a question of C++ than flex/bison, but maybe there is some trick in flex/bison that I am not aware of that will help me.

Make generates this:

parser.y: In function ‘int yyparse()’: parser.y:127:146: error: invalid initialization of reference of type ‘std::vector<double>&’ from expression of type ‘std::vector<double>*’ 

In file included from parser.y:21: values.h:18:76: note: in passing argument 3 of ‘double evaluateFold(Operators, Operators, std::vector<double>&)’ 

Below is a sample of what the fold function would interpret/evaluate.

// Test Left Fold function main returns integer; begin fold left - (3, 2, 1) endfold; end;