50 lines
1.6 KiB
C++
50 lines
1.6 KiB
C++
/** @file Binding.hpp
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*
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* @author Roland Conybeare, Jan 2026
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**/
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#pragma once
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#include <cstdint>
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namespace xo {
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namespace scm {
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class Binding {
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public:
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static constexpr int32_t s_link_sentinel = -2;
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static constexpr int32_t s_link_global = -1;
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public:
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Binding() : i_link_{-2}, j_slot_{-1} {}
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Binding(int32_t i_link, int32_t j_slot)
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: i_link_{i_link}, j_slot_{j_slot} {}
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static Binding null() { return Binding(); }
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/** global bindings are located by symbol name **/
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static Binding global() { return Binding(s_link_global, 0); }
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static Binding local(int32_t j_slot) { return Binding(0, j_slot); }
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bool is_global() const { return i_link_ == s_link_global; }
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bool is_local() const { return (i_link_ == 0) && (j_slot_ >= 0); }
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int32_t i_link() const noexcept { return i_link_; }
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int32_t j_slot() const noexcept { return j_slot_; }
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private:
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/**
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* >= 0: number of parent links to traverse
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* to a fixed-size frame
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* -1: resolve globally
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* -2: sentinel (binding info not computed)
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**/
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int32_t i_link_ = s_link_sentinel;
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/** if @ref i_link_ >= 0, frame offset
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* (in 'variables' not bytes).
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* ignored if @ref i_link_ is global
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**/
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int32_t j_slot_ = -1;
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};
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} /*namespace scm*/
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} /*namespace xo*/
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/* Binding.hpp */
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