Beispiel #1
0
  /**
   * Fills in all used scopes of the given one.
   *
   * @param curr current scope
   * @return IDs of all directly reachable scopes
   * @throws QueryException if a variable directly calls itself
   */
  private int[] neighbors(final Scope curr) throws QueryException {
    final IntList adj = new IntList(0);
    final boolean ok =
        curr.visit(
            new ASTVisitor() {
              @Override
              public boolean staticVar(final StaticVar var) {
                return var != curr && neighbor(var);
              }

              @Override
              public boolean staticFuncCall(final StaticFuncCall call) {
                return neighbor(call.func());
              }

              @Override
              public boolean inlineFunc(final Scope sub) {
                return sub.visit(this);
              }

              @Override
              public boolean funcItem(final FuncItem func) {
                return neighbor(func);
              }

              /**
               * Adds a neighbor of the currently inspected scope.
               *
               * @param scp the neighbor
               * @return {@code true} for convenience
               */
              private boolean neighbor(final Scope scp) {
                final int old = id(scp), id = old == -1 ? add(scp) : old;
                if (old == -1 || !adj.contains(id)) adj.add(id);
                return true;
              }
            });

    if (!ok) {
      final StaticVar var = (StaticVar) curr;
      throw CIRCREF_X.get(var.info, "$" + var.name);
    }
    return adj.finish();
  }
Beispiel #2
0
  /**
   * Algorithm of Tarjan for computing the strongly connected components of a graph.
   *
   * @param v current node
   * @throws QueryException if a variable directly calls itself
   */
  private void tarjan(final int v) throws QueryException {
    final int ixv = 2 * v, llv = ixv + 1, idx = next++;
    while (list.size() <= llv) list.add(-1);
    list.set(ixv, idx);
    list.set(llv, idx);

    stack.push(v);

    for (final int w : adjacentTo(v)) {
      final int ixw = 2 * w, llw = ixw + 1;
      if (list.size() <= ixw || list.get(ixw) < 0) {
        // Successor w has not yet been visited; recurse on it
        tarjan(w);
        list.set(llv, Math.min(list.get(llv), list.get(llw)));
      } else if (stack.contains(w)) {
        // Successor w is in stack S and hence in the current SCC
        list.set(llv, Math.min(list.get(llv), list.get(ixw)));
      }
    }

    // If v is a root node, pop the stack and generate an SCC
    if (list.get(llv) == list.get(ixv)) {
      int w;
      Scope[] out = null;
      do {
        w = stack.pop();
        final Scope scp = scopes.get(w);
        out = out == null ? new Scope[] {scp} : Array.add(out, scp);
      } while (w != v);
      result.add(out);
    }
  }