93 lines
3.6 KiB
C++
93 lines
3.6 KiB
C++
/** @file LocalEnv.hpp **/
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#include "Env.hpp"
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#include "CVector.hpp"
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#include "xo/alloc/IAlloc.hpp"
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#include "xo/expression/LocalSymtab.hpp"
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#include <cstddef>
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#include <cstdint>
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namespace xo {
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namespace scm {
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/** @class LocalEnv
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* @brief Represent a single runtime stack frame for a Schematika function
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*
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* LocalEnv intended to be used for interpreted functions.
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*
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* Compiled functions will still likely have stack frames, but need not use the
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* @ref LocalEnv class
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*
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* memory layout:
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* ^
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* +-----------------------+ |
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* | vtable | |
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* +-----------------------+ |
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* | .parent +------/
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* +------------+----------+
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* | .slot_v_ | .n_ |
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* | +----------+
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* | | .v_ +------\
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* +------------+----------+ <--/
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* | .v_[0] +---------> Object(1)
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* +-----------------------+
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* . .. .
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* +-----------------------+
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* | .v_[.n_-1] +---------> Object(n)
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* +-----------------------+
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**/
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class LocalEnv : public Env {
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public:
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using TaggedPtr = xo::reflect::TaggedPtr;
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public:
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LocalEnv(gc::IAlloc * mm, gp<LocalEnv> p, const rp<LocalSymtab> & s, std::size_t n);
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/** create frame using allocator @p mm,
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* with parent @p p and exactly @p n_slot object pointers.
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* variable types are taken from symbol table @p s.
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**/
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static gp<LocalEnv> make(gc::IAlloc * mm,
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gp<LocalEnv> p,
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const rp<LocalSymtab> & s,
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std::size_t n_slot);
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/** reflect LocalEnv object representation **/
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static void reflect_self();
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gp<LocalEnv> parent() const { return parent_; }
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std::size_t size() const { return slot_v_.size(); }
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gp<Object> operator[](std::size_t i) const { return slot_v_[i]; }
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gp<Object> & operator[](std::size_t i) { return slot_v_[i]; }
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// inherited from Env..
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virtual bool local_contains_var(const std::string & vname) const final override;
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/** LocalEnv policy is that variable can be established once only.
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* For example function arguments must all have distinct names
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**/
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virtual void establish_var(bp<Variable> v) final override;
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// inherited from Object..
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virtual TaggedPtr self_tp() const final override;
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virtual void display(std::ostream & os) const final override;
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virtual std::size_t _shallow_size() const final override;
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virtual Object * _shallow_copy(gc::IAlloc * mm) const final override;
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virtual std::size_t _forward_children(gc::IAlloc * /*gc*/) final override;
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private:
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/** parent stack frame **/
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gp<LocalEnv> parent_;
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/** origin symbol table. records variable names and bindings.
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* for a binding path p with leaf slot index j = p.j_slot_:
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* @c slot_v_[j] holds value associated with variable @c symtab_->argv_[j]
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**/
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rp<LocalSymtab> symtab_;
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/** environment contents **/
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CVector<gp<Object>> slot_v_;
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};
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} /*namespace scm*/
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} /*namespace xo*/
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/* end LocalEnv.hpp */
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