111 lines
3.9 KiB
C++
111 lines
3.9 KiB
C++
/** @file DGlobalSymtab.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 "Binding.hpp"
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#include "DVariable.hpp"
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#include <xo/object2/DArray.hpp>
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#include <xo/arena/DArenaHashMap.hpp>
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namespace xo {
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namespace scm {
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class DUniqueString;
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/** @class DGlobalSymtab
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* @brief symbol table for toplevel environment
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*
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* We're using DArenaHashMap to store <key,binding> pairs.
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* Both of these are outside GC-space, so we don't need collector
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* to traverse these.
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**/
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class DGlobalSymtab {
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public:
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using key_type = const DUniqueString *;
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using value_type = Binding;
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using ArenaHashMapConfig = xo::map::ArenaHashMapConfig;
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using repr_type = xo::map::DArenaHashMap<key_type, Binding::slot_type>;
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using ACollector = xo::mm::ACollector;
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using AAllocator = xo::mm::AAllocator;
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using MemorySizeVisitor = xo::mm::MemorySizeVisitor;
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public:
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/** @defgroup scm-globalsymtab-ctors constructors **/
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///@{
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DGlobalSymtab(repr_type * map, DArray * vars);
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/** create instance.
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* Use memory from @p fixed_mm for @ref map_.
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* Use memory from @p mm for DGlobalSymtab instance.
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* Hashmap configured per @p cfg.
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**/
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DGlobalSymtab * make(obj<AAllocator> fixed_mm,
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obj<AAllocator> mm,
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const ArenaHashMapConfig & cfg);
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///@}
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/** @defgroup scm-globalsymtab-access-methods access methods **/
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///@{
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/** visit symtab-owned memory pools; call visitor(info) for each **/
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void visit_pools(const MemorySizeVisitor & visitor) const;
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/** lookup global symbol with name @p sym **/
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DVariable * lookup_variable(const DUniqueString * sym) const noexcept;
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///@}
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/** @defgroup scm-globalsymtab-general-methods general methods **/
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///@{
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/** establish binding for @p sym, with type described by @p typeref,
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* replacing existing global (if present) with the same name.
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* Use memory from @p mm to create variable-expr
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**/
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DVariable * establish_variable(obj<AAllocator> mm,
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const DUniqueString * sym,
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TypeRef typeref);
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///@}
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/** @defgroup scm-globalsymtab-symboltable-facet symboltable facet **/
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///@{
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/** true for global symbol table **/
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bool is_global_symtab() const noexcept { return true; }
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/** lookup binding for variable @p sym **/
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Binding lookup_binding(const DUniqueString * sym) const noexcept;
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///@}
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/** @defgroup scm-globalsymtab-gcobject-facet gcobject facet **/
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///@{
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std::size_t shallow_size() const noexcept;
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DGlobalSymtab * shallow_copy(obj<AAllocator> mm) const noexcept;
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std::size_t forward_children(obj<ACollector> gc) noexcept;
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///@}
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private:
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/** map symbols -> bindings.
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* Minor point: storing offsets instead of Variables allows us to omit
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* iterating over map elements during GC. Possible savings if map_ slots
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* sparsely populated.
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**/
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repr_type * map_ = nullptr;
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/** array of variables.
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* When S is a unique-string for a global symbol, then:
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* 1. map_[S] is unique global index i(S) for S.
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* 2. vars_[i(S)] is variable-expr var(S) for S
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* 3. var(S)->name == S
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**/
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DArray * vars_ = nullptr;
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};
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} /*namespace scm*/
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} /*namespace xo*/
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/* end DGlobalSymtab.hpp */
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