lib/loxby/helpers/environment.rb in loxby-0.0.2 vs lib/loxby/helpers/environment.rb in loxby-0.0.3

@@ -1,13 +1,12 @@
 # frozen_string_literal: true
 
 require_relative 'errors'
 
 class Lox
-  # Lox::Environment stores namespace for
-  # a Lox interpreter. Environments can be
-  # nested (for scope).
+  # Stores namespaces for a Lox interpreter.
+  # Environments can be nested (for scope).
   class Environment
     def initialize(enclosing = nil)
       @enclosing = enclosing
       @values = {}
     end
@@ -15,33 +14,45 @@
     def undefined_variable(name)
       Lox::RunError.new(name, "Undefined variable '#{name.lexeme}'")
     end
 
     def []=(name, value)
-      @values[name.lexeme] = value
+      set name.lexeme, value
     end
 
-    def exists?(name)
+    # Used to set a static association. For example:
+    #   env.set 'static_function_name', static_function
+    def set(name, value)
+      @values[name] = value
+    end
+
+    def declared?(name)
+      # We can't check for a dummy value
+      # since loxby uses `nil` as well
       @values.keys.member? name.lexeme
     end
 
     def [](name)
-      if exists? name
+      if @values[name.lexeme]
         @values[name.lexeme]
+      elsif declared? name
+        raise Lox::RunError.new(name, "Declared variable not initialized: '#{name.lexeme}'")
       elsif @enclosing
         @enclosing[name]
       else
         raise undefined_variable(name)
       end
     end
 
     def assign(name, value)
-      if exists? name
+      if declared? name
         self[name] = value
       elsif @enclosing
         @enclosing.assign(name, value)
       else
         raise undefined_variable(name)
       end
     end
+
+    alias define []=
   end
 end