momiji::extractASTValue

Defined in header <momiji/Parser.h>

1. Parameters:
   • const momiji::Operand& operand : The operand of which the function should resolve the AST.
   • const momiji::LabelInfo& labels : The labels present in the code.
   Returns: The register value in the operand if it is a RegOperand, zero otherwise.

This function takes any Operand: if it is a ASTOperand then it will resolve the AST and return the computed value, else it will return zero.

This is mostly useful in generic code, otherwise one should have to switch on the Operand variant, and that would be annoying.

Example

Instead of this:

momiji::Operand op = /* ... */;

// ...
// A call stack later

std::int32_t regval = 0;

std::visit(op, asl::overloaded{
    [&regval] (const momiji::operands::DataRegister& op) {
        regval = op.reg;
    },

    [&regval] (const momiji::operands::AddressRegister& op) {
        regval = op.reg;
    },

    [&regval] (const momiji::operands::Address& op) {
        regval = op.reg;
    },

    // Repeat for all the other classes that expose 'reg'
    // ...

    [] (auto&&) {
        // Do nothing if none of the above
    }
});

You can write this instead:

momiji::Operand op = /* ... */;

const std::int32_t regval = momiji::extractReg(op);