63 lines
2 KiB
C++
63 lines
2 KiB
C++
/** @file Binding.hpp
|
|
*
|
|
* @author Roland Conybeare, Jan 2026
|
|
**/
|
|
|
|
#pragma once
|
|
|
|
#include <iostream>
|
|
#include <cstdint>
|
|
|
|
namespace xo {
|
|
namespace scm {
|
|
class Binding {
|
|
public:
|
|
static constexpr int32_t c_link_sentinel = -2;
|
|
static constexpr int32_t c_link_global = -1;
|
|
|
|
public:
|
|
Binding() : i_link_{-2}, j_slot_{-1} {}
|
|
Binding(int32_t i_link, int32_t j_slot)
|
|
: i_link_{i_link}, j_slot_{j_slot} {}
|
|
|
|
static Binding null() { return Binding(); }
|
|
/** global bindings are located by symbol name **/
|
|
static Binding global() { return Binding(c_link_global, 0); }
|
|
static Binding local(int32_t j_slot) { return Binding(0, j_slot); }
|
|
static Binding relative(int32_t i_link, Binding def);
|
|
|
|
bool is_null() const {
|
|
return (i_link_ == c_link_sentinel) && (j_slot_ == -1);
|
|
}
|
|
bool is_global() const { return i_link_ == c_link_global; }
|
|
bool is_local() const { return (i_link_ == 0) && (j_slot_ >= 0); }
|
|
|
|
int32_t i_link() const noexcept { return i_link_; }
|
|
int32_t j_slot() const noexcept { return j_slot_; }
|
|
|
|
/** print human-readable repr to stream @p os **/
|
|
void print(std::ostream & os) const;
|
|
|
|
private:
|
|
/**
|
|
* >= 0: number of parent links to traverse
|
|
* to a fixed-size frame
|
|
* -1: resolve globally
|
|
* -2: sentinel (binding info not computed)
|
|
**/
|
|
int32_t i_link_ = c_link_sentinel;
|
|
/** if @ref i_link_ >= 0, frame offset
|
|
* (in 'variables' not bytes).
|
|
* ignored if @ref i_link_ is global
|
|
**/
|
|
int32_t j_slot_ = -1;
|
|
};
|
|
|
|
inline std::ostream & operator<< (std::ostream & os, Binding x) {
|
|
x.print(os);
|
|
return os;
|
|
}
|
|
} /*namespace scm*/
|
|
} /*namespace xo*/
|
|
|
|
/* Binding.hpp */
|