1 files changed, 49 insertions, 0 deletions
diff --git a/symtab.cc b/symtab.cc
index af0b620..fb81bfe 100644
--- a/symtab.cc
+++ b/symtab.cc
@@ -27,8 +27,18 @@
 
 #include "log.h"
 #include "strutil.h"
+#include "var.h"
+
+struct SymbolData {
+  SymbolData()
+      : gv(kUndefined) {
+  }
+
+  Var* gv;
+};
 
 vector<string*>* g_symbols;
+static vector<SymbolData> g_symbol_data;
 
 Symbol kEmptySym = Symbol(Symbol::IsUninitialized());
 Symbol kShellSym = Symbol(Symbol::IsUninitialized());
@@ -37,6 +47,45 @@ Symbol::Symbol(int v)
     : v_(v) {
 }
 
+Var* Symbol::GetGlobalVar() const {
+  if (static_cast<size_t>(v_) >= g_symbol_data.size()) {
+    g_symbol_data.resize(v_ + 1);
+  }
+  Var* v = g_symbol_data[v_].gv;
+  if (v->Origin() == VarOrigin::ENVIRONMENT ||
+      v->Origin() == VarOrigin::ENVIRONMENT_OVERRIDE) {
+    Vars::add_used_env_vars(*this);
+  }
+  return v;
+}
+
+void Symbol::SetGlobalVar(Var* v) const {
+  if (static_cast<size_t>(v_) >= g_symbol_data.size()) {
+    g_symbol_data.resize(v_ + 1);
+  }
+  Var* orig = g_symbol_data[v_].gv;
+  if (orig->Origin() == VarOrigin::OVERRIDE ||
+      orig->Origin() == VarOrigin::ENVIRONMENT_OVERRIDE) {
+    return;
+  }
+  if (orig->Origin() == VarOrigin::AUTOMATIC) {
+    ERROR("overriding automatic variable is not implemented yet");
+  }
+  if (orig->IsDefined())
+    delete orig;
+  g_symbol_data[v_].gv = v;
+}
+
+ScopedGlobalVar::ScopedGlobalVar(Symbol name, Var* var)
+    : name_(name), orig_(NULL) {
+  orig_ = name.GetGlobalVar();
+  g_symbol_data[name_.val()].gv = var;
+}
+
+ScopedGlobalVar::~ScopedGlobalVar() {
+  g_symbol_data[name_.val()].gv = orig_;
+}
+
 class Symtab {
  public:
   Symtab() {