xo-expression2 stack: + mvp DGlobalSymtab impl

include/xo/expression2/Binding.hpp

@@ -12,6 +12,8 @@ namespace xo {
     namespace scm {
         class Binding {
         public:
+            using slot_type = int32_t;
+
             static constexpr int32_t c_link_sentinel = -2;
             static constexpr int32_t c_link_global = -1;
 
@@ -22,7 +24,7 @@ namespace xo {
 
             static Binding null() { return Binding(); }
             /** global bindings are located by symbol name **/
-            static Binding global() { return Binding(c_link_global, 0); }
+            static Binding global(int32_t j_slot) { return Binding(c_link_global, j_slot); }
             static Binding local(int32_t j_slot) { return Binding(0, j_slot); }
             static Binding relative(int32_t i_link, Binding def);
 

include/xo/expression2/DGlobalSymtab.hpp

@@ -6,6 +6,8 @@
 #pragma once
 
 #include "Binding.hpp"
+#include "DVariable.hpp"
+#include <xo/object2/DArray.hpp>
 #include <xo/arena/DArenaHashMap.hpp>
 
 namespace xo {
@@ -23,7 +25,8 @@ namespace xo {
         public:
             using key_type = const DUniqueString *;
             using value_type = Binding;
-            using repr_type = xo::map::DArenaHashMap<key_type, value_type>;
+            using repr_type = xo::map::DArenaHashMap<key_type, Binding::slot_type>;
+            using AAllocator = xo::mm::AAllocator;
             using MemorySizeVisitor = xo::mm::MemorySizeVisitor;
 
         public:
@@ -31,6 +34,17 @@ namespace xo {
             void visit_pools(const MemorySizeVisitor & visitor) const;
 
         public:
+            /** lookup global symbol with name @p sym **/
+            DVariable * lookup_variable(const DUniqueString * sym) const noexcept;
+
+            /** establish binding for @p sym, with type described by @p typeref,
+             *  replacing existing global (if present) with the same name.
+             *  Use memory from @p mm to create variable-expr
+             **/
+            DVariable * establish_variable(obj<AAllocator> mm,
+                                           const DUniqueString * sym,
+                                           TypeRef typeref);
+
             /** @defgroup xo-expression2-symboltable-facet symboltable facet**/
             ///@{
 
@@ -49,6 +63,13 @@ namespace xo {
             /** map symbols -> bindings **/
             repr_type map_;
             
+            /** array of variables.
+             *  When S is a unique-string for a global symbol, then:
+             *  1. map_[S] is unique global index i(S) for S.
+             *  2. vars_[i(S)] is variable-expr var(S) for S
+             *  3. var(S)->name == S
+             **/
+            DArray * vars_ = nullptr;
         };
 
     } /*namespace scm*/

include/xo/expression2/DLocalSymtab.hpp

@@ -73,7 +73,7 @@ namespace xo {
                 return slots_[ix.j_slot()].var_;
             }
 
-            /** increase slot size (provided beleow capacity) to append
+            /** increase slot size (provided below capacity) to append
              *  binding for one local variable.  Local variable will be allocated
              *  from @p mm, named @p name, with type described by @p typeref.
              **/

src/expression2/DGlobalSymtab.cpp

@@ -5,20 +5,108 @@
 
 #include "DGlobalSymtab.hpp"
 #include "DUniqueString.hpp"
+#include <xo/expression2/Expression.hpp>
+#include <xo/expression2/Variable.hpp>
+#include <xo/gc/GCObject.hpp>
+#include <xo/facet/FacetRegistry.hpp>
 #include <xo/indentlog/scope.hpp>
 
 namespace xo {
+    using xo::mm::AGCObject;
+
     namespace scm {
 
+#ifdef NOT_YET
+        DVariable *
+        DGlobalSymtab::lookup_binding(Binding ix) noexcept
+        {
+            assert(ix.i_link() == -1);
+            assert(ix.j_slot() >= 0);
+            assert(vars_);
+            assert(std::uint64_t(ix.j_slot()) < vars_->size());
+
+            auto var_gco = obj<AGCObject,DVariable>::from((*vars_)[ix.j_slot()]);;
+            auto var = var_gco.to_facet<AExpression>();
+
+            assert(var.data());
+
+            return var.data();
+        }
+#endif
+
+        DVariable *
+        DGlobalSymtab::lookup_variable(const DUniqueString * sym) const noexcept
+        {
+            Binding existing = this->lookup_binding(sym);
+
+            if (existing.is_null())
+                return nullptr;
+
+            auto var_gco = obj<AGCObject,DVariable>::from((*vars_)[existing.j_slot()]);
+            auto var = var_gco.to_facet<AExpression>();
+
+            assert(var.data());
+
+            return var.data();
+        }
+
+        DVariable *
+        DGlobalSymtab::establish_variable(obj<AAllocator> mm,
+                                          const DUniqueString * sym,
+                                          TypeRef typeref)
+        {
+            DVariable * var = this->lookup_variable(sym);
+
+            if (!var) {
+                assert(vars_);
+
+                DArray::size_type n = vars_->size();
+
+                /** make sure vars_ has room **/
+                if (n == vars_->capacity()) {
+                    // reallocate with more capacity
+                    DArray * vars_2x = DArray::copy(mm, vars_, vars_->capacity() * 2);
+
+                    assert(vars_2x);
+
+                    this->vars_ = vars_2x;
+                }
+
+                /** create new variable **/
+                Binding binding = Binding::global(n);
+                var = DVariable::make(mm, sym, typeref, binding);
+
+                if (!var) {
+                    // something terribly wrong
+                    assert(false);
+                    return var;
+                }
+
+                map_[sym] = binding.j_slot();
+
+                bool ok = vars_->push_back(obj<AGCObject,DVariable>(var));
+
+                if (!ok)
+                    assert(false);
+            }
+
+            return var;
+        }
+
         Binding
         DGlobalSymtab::lookup_binding(const DUniqueString * sym) const noexcept
         {
-            (void)sym;
+            assert(sym);
 
             scope log(XO_DEBUG(true), "stub");
             log && log(xtag("sym", std::string_view(*sym)));
 
-            return Binding();
+            auto ix = map_.find(sym);
+
+            if (ix == map_.end()) 
+                return Binding::null();
+
+            return Binding::global(ix->second);
         }
 
     } /*namespace scm*/