Globals to compiler

compiler/symbol_table.go

@@ -0,0 +1,39 @@
+package compiler
+
+type SymbolScope string
+
+const (
+	GlobalScope SymbolScope = "Global"
+)
+
+type Symbol struct {
+	Name  string
+	Scope SymbolScope
+	Index int
+}
+
+type SymbolTable struct {
+	store          map[string]Symbol
+	numDefinitions int
+}
+
+func NewSymbolTable() *SymbolTable {
+	s := make(map[string]Symbol)
+	return &SymbolTable{store: s}
+}
+
+func (s *SymbolTable) Define(name string) Symbol {
+	symbol := Symbol{
+		Name:  name,
+		Scope: GlobalScope,
+		Index: s.numDefinitions,
+	}
+	s.store[name] = symbol
+	s.numDefinitions++
+	return symbol
+}
+
+func (s *SymbolTable) Resolve(name string) (Symbol, bool) {
+	obj, ok := s.store[name]
+	return obj, ok
+}