Roland Conybeare
a33f75f6f4
subrepo: subdir: "xo-expression2" merged: "9823ce36" upstream: origin: "git@github.com:Rconybea/xo-expression2.git" branch: "main" commit: "9823ce36" git-subrepo: version: "0.4.9" origin: "???" commit: "???"
65 lines
2.1 KiB
C++
65 lines
2.1 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 <iostream>
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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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using slot_type = int32_t;
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static constexpr int32_t c_link_sentinel = -2;
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static constexpr int32_t c_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(int32_t j_slot) { return Binding(c_link_global, j_slot); }
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static Binding local(int32_t j_slot) { return Binding(0, j_slot); }
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static Binding relative(int32_t i_link, Binding def);
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bool is_null() const {
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return (i_link_ == c_link_sentinel) && (j_slot_ == -1);
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}
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bool is_global() const { return i_link_ == c_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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/** print human-readable repr to stream @p os **/
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void print(std::ostream & os) const;
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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_ = c_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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inline std::ostream & operator<< (std::ostream & os, Binding x) {
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x.print(os);
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return os;
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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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