import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
@Override
public boolean shouldTraverse(NodeTraversal t, Node n, Node parent) {
  GraphNode<Node, Branch> gNode = t.getControlFlowGraph().getNode(n);
  if (gNode != null && gNode.getAnnotation() != GraphReachability.REACHABLE) {

    // Only report error when there are some line number informations.
    // There are synthetic nodes with no line number informations, nodes
    // introduce by other passes (although not likely since this pass should
    // be executed early) or some rhino bug.
    if (n.getLineno() != -1 &&
        // Allow spurious semi-colons and spurious breaks.
        n.getType() != Token.EMPTY && n.getType() != Token.BREAK) {
      compiler.report(JSError.make(t, n, level, UNREACHABLE_CODE));
      // From now on, we are going to assume the user fixed the error and not
      // give more warning related to code section reachable from this node.
      new GraphReachability<Node, ControlFlowGraph.Branch>(
          t.getControlFlowGraph()).recompute(n);

      // Saves time by not traversing children.
      return false;
    }
  }
  return true;
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
@Override
public boolean shouldTraverse(NodeTraversal t, Node n, Node parent) {
  GraphNode<Node, Branch> gNode = t.getControlFlowGraph().getNode(n);
  if (gNode != null && gNode.getAnnotation() != GraphReachability.REACHABLE) {

    // Only report error when there are some line number informations.
    // There are synthetic nodes with no line number informations, nodes
    // introduce by other passes (although not likely since this pass should
    // be executed early) or some rhino bug.
    if (n.getLineno() != -1 &&
        // Allow spurious semi-colons and spurious breaks.
        !n.isEmpty() && !n.isBreak()) {
      compiler.report(t.makeError(n, level, UNREACHABLE_CODE));
      // From now on, we are going to assume the user fixed the error and not
      // give more warning related to code section reachable from this node.
      new GraphReachability<Node, ControlFlowGraph.Branch>(
          t.getControlFlowGraph()).recompute(n);

      // Saves time by not traversing children.
      return false;
    }
  }
  return true;
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
@Override
public boolean shouldTraverse(NodeTraversal t, Node n, Node parent) {
  GraphNode<Node, Branch> gNode = t.getControlFlowGraph().getNode(n);
  if (gNode != null && gNode.getAnnotation() != GraphReachability.REACHABLE) {

    // Only report error when there are some line number informations.
    // There are synthetic nodes with no line number informations, nodes
    // introduce by other passes (although not likely since this pass should
    // be executed early) or some rhino bug.
    if (n.getLineno() != -1 &&
        // Allow spurious semi-colons and spurious breaks.
        !n.isEmpty() && !n.isBreak()) {
      compiler.report(t.makeError(n, UNREACHABLE_CODE));
      // From now on, we are going to assume the user fixed the error and not
      // give more warning related to code section reachable from this node.
      new GraphReachability<>(t.getControlFlowGraph()).recompute(n);

      // Saves time by not traversing children.
      return false;
    }
  }
  return true;
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
@Override
public boolean shouldTraverse(NodeTraversal t, Node n, Node parent) {
  GraphNode<Node, Branch> gNode = t.getControlFlowGraph().getNode(n);
  if (gNode != null && gNode.getAnnotation() != GraphReachability.REACHABLE) {

    // Only report error when there are some line number informations.
    // There are synthetic nodes with no line number informations, nodes
    // introduce by other passes (although not likely since this pass should
    // be executed early) or some rhino bug.
    if (n.getLineno() != -1 &&
        // Allow spurious semi-colons and spurious breaks.
        !n.isEmpty() && !n.isBreak()) {
      compiler.report(t.makeError(n, UNREACHABLE_CODE));
      // From now on, we are going to assume the user fixed the error and not
      // give more warning related to code section reachable from this node.
      new GraphReachability<>(
          t.getControlFlowGraph()).recompute(n);

      // Saves time by not traversing children.
      return false;
    }
  }
  return true;
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
  if (parent == null) {
    return;
  }
  if (n.getType() == Token.FUNCTION || n.getType() == Token.SCRIPT) {
    return;
  }
  // Removes TRYs that had its CATCH removed and/or empty FINALLY.
  if (n.getType() == Token.TRY) {
    Node body = n.getFirstChild();
    Node catchOrFinallyBlock = body.getNext();
    Node finallyBlock = catchOrFinallyBlock.getNext();

    if (!catchOrFinallyBlock.hasChildren() &&
        (finallyBlock == null || !finallyBlock.hasChildren())) {
      n.removeChild(body);
      parent.replaceChild(n, body);
      compiler.reportCodeChange();
      n = body;
    }
  }
  GraphNode<Node, Branch> gNode = curCfg.getNode(n);
  if (gNode == null) { // Not in CFG.
    return;
  }
  if (gNode.getAnnotation() != GraphReachability.REACHABLE ||
      (removeNoOpStatements && !NodeUtil.mayHaveSideEffects(n))) {
    removeDeadExprStatementSafely(n, parent);
  }
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
private void connectUnknowns() {
  for (GraphNode<Name, Reference> node : graph.getNodes()) {
    Name name = node.getValue();
    String propName = name.getPropertyName();
    if (propName == null) {
      continue;
    }
    Collection<NameUse> uses = unknownNameUse.get(propName);
    if (uses != null) {
      for (NameUse use : uses) {
        graph.connect(use.name, use.reference, name);
      }
    }
  }
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
/**
 * Gets the must reaching definition of a given node. The node must be one of
 * the control flow graph nodes.
 *
 * @param name name of the variable. It can only be names of local variable
 *     that are not function parameters, escaped variables or variables
 *     declared in catch.
 * @param useNode the location of the use where the definition reaches.
 */
Node getDef(String name, Node useNode) {
  Preconditions.checkArgument(getCfg().hasNode(useNode));
  GraphNode<Node, Branch> n = getCfg().getNode(useNode);
  FlowState<MustDef> state = n.getAnnotation();
  Definition def = state.getIn().reachingDef.get(jsScope.getVar(name));
  if (def == null) {
    return null;
  } else {
    return def.node;
  }
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
/**
 * Remove all properties under a given name if the property name is
 * never referenced.
 */
private void removeUnusedProperties(NameReferenceGraph graph) {
  for (GraphNode<Name, Reference> node : graph.getNodes()) {
    Name name = node.getValue();
    NameInfo nameInfo = node.getAnnotation();
    if (nameInfo == null || !nameInfo.isReferenced()) {
      name.remove();
      compiler.reportCodeChange();
      logger.fine("Removed unused name" + name);
    }
  }
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
private NameInfo getInfo(Name symbol) {
  GraphNode<Name, Reference> name = graph.getNode(symbol);
  NameInfo info = name.getAnnotation();
  if (info == null) {
    info = new NameInfo();
    name.setAnnotation(info);
  }
  return info;
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
public void recompute(N reachableNode) {
  GraphNode<N, E> newReachable = graph.getNode(reachableNode);
  Preconditions.checkState(newReachable.getAnnotation() != REACHABLE);
  newReachable.setAnnotation(REACHABLE);
  FixedPointGraphTraversal.newTraversal(this)
      .computeFixedPoint(graph, reachableNode);
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
@Override
public boolean traverseEdge(N source, E e, N destination) {
  if (graph.getNode(source).getAnnotation() == REACHABLE) {
    GraphNode<N, E> destNode = graph.getNode(destination);
    if (destNode.getAnnotation() != REACHABLE) {
      destNode.setAnnotation(REACHABLE);
      return true;
    }
  }
  return false;
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
/**
 * Validate that each node has been colored and connected nodes have different
 * coloring.
 */
private static <N, E> void validateColoring(Graph<N, E> graph) {
  for (GraphNode<N, E> node : graph.getNodes()) {
    assertTrue(node.getAnnotation() != null);
  }
  for (GraphEdge<N, E> edge : graph.getEdges()) {
    Color c1 = edge.getNodeA().getAnnotation();
    Color c2 = edge.getNodeB().getAnnotation();
    assertTrue(c1 != null);
    assertTrue(c2 != null);
    assertTrue(!c1.equals(c2));
  }
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
private <T extends GraphNode<String, String>> void assertListCount(
    List<T> list, String target, int count) {
  for (GraphNode<String, String> node : list) {
    if (node.getValue().equals(target)) {
      count--;
    }
  }
  assertTrue(count == 0);
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
private <T extends GraphNode<String, String>> void assertSetEquals(
    List<T> list, String ... targets) {
  Set<String> set = new HashSet<String>();
  for (GraphNode<String, String> node : list) {
    set.add(node.getValue());
  }
  Set<String> otherSet = new HashSet<String>();
  for (String target : targets) {
    otherSet.add(target);
  }
  assertTrue(otherSet.equals(set));
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
boolean dependsOnOuterScopeVars(String name, Node useNode) {
  Preconditions.checkArgument(getCfg().hasNode(useNode));
  GraphNode<Node, Branch> n = getCfg().getNode(useNode);
  FlowState<MustDef> state = n.getAnnotation();
  Definition def = state.getIn().reachingDef.get(jsScope.getVar(name));
  for (Var s : def.depends) {
    if (s.scope != jsScope) {
      return true;
    }
  }
  return false;
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
/**
 * Remove all properties under a given name if the property name is
 * never referenced.
 */
private void removeUnusedProperties(NameReferenceGraph graph) {
  for (GraphNode<Name, Reference> node : graph.getNodes()) {
    Name name = node.getValue();
    NameInfo nameInfo = node.getAnnotation();
    if (nameInfo == null || !nameInfo.isReferenced()) {
      if (canModifyExterns || !name.isExtern()) {
        name.remove();
        compiler.reportCodeChange();
        logger.fine("Removed unused name" + name);
      }
    }
  }
}
 

import com.google.javascript.jscomp.graph.GraphNode; //导入依赖的package包/类
@Override
public boolean shouldTraverse(NodeTraversal t, Node n, Node parent) {
  if (!shouldCheck(n)) {
    return false;
  }

  if (scopeNeedsInit) {
    initScope(t.getControlFlowGraph());
    scopeNeedsInit = false;
  }

  GraphNode<Node, Branch> gNode = t.getControlFlowGraph().getNode(n);
  if (gNode != null && gNode.getAnnotation() != GraphReachability.REACHABLE) {

    // Only report error when there are some line number informations.
    // There are synthetic nodes with no line number informations, nodes
    // introduce by other passes (although not likely since this pass should
    // be executed early) or some rhino bug.
    if (n.getLineno() != -1 &&
        // Allow spurious semi-colons and spurious breaks.
        n.getType() != Token.EMPTY && n.getType() != Token.BREAK) {
      compiler.report(t.makeError(n, level, UNREACHABLE_CODE));
      // From now on, we are going to assume the user fixed the error and not
      // give more warning related to code section reachable from this node.
      new GraphReachability<Node, ControlFlowGraph.Branch>(
          t.getControlFlowGraph()).recompute(n);

      // Saves time by not traversing children.
      return false;
    }
  }
  return true;
}