Software Suitable for Expanding and Integrating Long Algebraic Expressions

Question

Does anyone know if available software packages can cope with very long algebraic expressions which may involve hundreds or thousands of terms.

For example here is a (prettified) example input to a homemade VB6 program which performs addition, multiplication, simple integration and binomial expansion:-

{@PRODUCT!
    ([V])
    ({@SUM!         
        ([V*h]+[-g*h]) 
        ({@PRODUCT! 
            ([(1/2)]) 
            ([V*h]+[-g*h])
            ([-3*e^2]+[E^2])
            ([V^-2])
            ({@BINOMEXPAND!
                ([1]+[-2*g*V^-1]+[g^2*V^-2]+[h^2*V^-2]);(<-1>)
             })
         })
    })
    ({@SUM!
        ([e^2*E^-2])
        ({@PRODUCT!
            ([2*e*V^-1])
            ({@BINOMEXPAND! ([1]+[-2*g*V^-1]+[g^2*V^-2]+[h^2*V^-2]);(<-1/2>)})  })
            ({@PRODUCT!
                ([E^2*V^-2])
                ({@BINOMEXPAND!([1]+[-2*g*V^-1]+[g^2*V^-2]+[h^2*V^-2]);(<-1>)})
             })
         })
         ({@BINOMEXPAND!
            ([1]
            {@PRODUCT!
                ([2*e*V^-1])
                ({@BINOMEXPAND!([1]+[-2*g*V^-1]+[g^2*V^-2]+[h^2*V^-2]);(<-1/2>)})
            }
            {@PRODUCT!
                ([E^2*V^-2])
                ({@BINOMEXPAND!([1]+[-2*g*V^-1]+[g^2*V^-2]+[h^2*V^-2]);(<-1>)})
            }
            );(<-1>)
          })
    })
}
{INTEGRATE: e>E}
{CULL RULE: "Exclude all terms with E power <1}

The program is becoming difficult to maintain and great care is needed to format the input correctly as errors are not always detected and spurious answers can result. So I would like to consider moving to a capable software package. But so far, I cannot tell, without digging deep, what packages might be capable of this size of problem.