initial commit

MicroJava Compiler/src/ssw/mj/impl/Tab.java

@@ -0,0 +1,100 @@
+package ssw.mj.impl;
+
+import ssw.mj.symtab.Obj;
+import ssw.mj.symtab.Scope;
+import ssw.mj.symtab.Struct;
+
+public final class Tab {
+
+  // Universe
+  public static final Struct noType = new Struct(Struct.Kind.None);
+  public static final Struct intType = new Struct(Struct.Kind.Int);
+  public static final Struct charType = new Struct(Struct.Kind.Char);
+  public static final Struct nullType = new Struct(Struct.Kind.Class);
+
+  public final Obj noObj, chrObj;
+  public Obj ordObj, lenObj;
+
+  /**
+   * Only used for reporting errors.
+   */
+  private final Parser parser;
+  /**
+   * The current top scope.
+   */
+  public Scope curScope = null;
+  // First scope opening (universe) will increase this to -1
+  /**
+   * Nesting level of current scope.
+   */
+  private int curLevel = -2;
+
+  public Tab(Parser p) {
+    parser = p;
+
+    // setting up "universe" (= predefined names)
+    // opening scope (curLevel goes to -1, which is the universe level)
+    openScope();
+
+    noObj = new Obj(Obj.Kind.Var, "noObj", noType);
+
+    insert(Obj.Kind.Type, "int", intType);
+    insert(Obj.Kind.Type, "char", charType);
+    insert(Obj.Kind.Con, "null", nullType);
+
+    chrObj = insert(Obj.Kind.Meth, "chr", charType);
+    openScope();
+    Obj iVarObj = insert(Obj.Kind.Var, "i", intType);
+    iVarObj.level = 1;
+    chrObj.nPars = curScope.nVars();
+    chrObj.locals = curScope.locals();
+    closeScope();
+
+    // TODO Exercise UE-P-4: build "ord" universe method and store in ordObj
+
+    // TODO Exercise UE-P-4: build "len" universe method and store in lenObj
+
+    // still on level -1
+    // now that the universe is constructed, the next node that will be added is the Program itself
+    // (which will open its own scope with level 0)
+  }
+
+  // ===============================================
+  // TODO Exercise UE-P-4: implementation of symbol table
+  // ===============================================
+
+  public void openScope() {
+    curScope = new Scope(curScope);
+    curLevel++;
+  }
+
+  public void closeScope() {
+    curScope = curScope.outer();
+    curLevel--;
+  }
+
+  public Obj insert(Obj.Kind kind, String name, Struct type) {
+    // TODO Exercise UE-P-4
+    return noObj;
+  }
+
+  /**
+   * Retrieves the object with <code>name</code> from the innermost scope.
+   */
+  public Obj find(String name) {
+    // TODO Exercise UE-P-4
+    return noObj;
+  }
+
+  /**
+   * Retrieves the field <code>name</code> from the fields of
+   * <code>type</code>.
+   */
+  public Obj findField(String name, Struct type) {
+    // TODO Exercise UE-P-4
+    return noObj;
+  }
+
+  // ===============================================
+  // ===============================================
+}