vorläufige solution für aufgabe 2.1

ws2011/Compiler I/Uebungen/2. Uebung/c1-ex02/SymbolTable.java

@@ -12,16 +12,26 @@ public final class SymbolTable {
   private List<List<String>> scopeStack;
 
   public SymbolTable () {
+      symtab = new Map<String, Stack<Declaration>>();
+      scopeStack = new List<List<String>>();
   }
 
   // Opens a new level in the identification table, 1 higher than the
   // current topmost level.
   public void openScope () {
+        // new empty list
+	scopeStack.add(new List<String>());
   }
 
   // Closes the topmost level in the identification table, discarding
   // all entries belonging to that level.
   public void closeScope () {
+      //delete from symtab
+      for(int i = 0; i < scopeStack.get(scopeStack.size() -1).size(); i++){
+         symtab.remove(scopeStack.get(scopeStack.size() -1).get(i));
+      }
+      // delete top list
+      scopeStack.remove(scopeStack.size()-1);
   }
 
   // Makes a new entry in the identification table for the given identifier
@@ -29,6 +39,8 @@ public final class SymbolTable {
   // duplicated is set to to true if there is already an entry for the
   // same identifier at the current level.
   public void enter (String id, Declaration attr) {
+      scopeStack.get(scopeStack.size()-1).add(id);
+      symtab.put(id, attr);
   }
 
   // Finds an entry for the given identifier in the identification table,
@@ -37,7 +49,7 @@ public final class SymbolTable {
   // Returns null if no entry is found.
   // otherwise returns the attribute field of the entry found.
   public Declaration retrieve (String id) {
-	  return null;
+	  return symtab.containsKey(id);
   }
 
 }