import com.google.javascript.jscomp.NameReferenceGraph.Reference; //导入依赖的package包/类
@Override
public void process(Node externs, Node root) {
  if (nameGraph == null) {
    NameReferenceGraphConstruction c =
        new NameReferenceGraphConstruction(compiler);
    c.process(externs, root);
    nameGraph = c.getNameReferenceGraph();
  }
  
  for (DiGraphNode<Name, Reference> node : 
      nameGraph.getDirectedGraphNodes()) {
    Name name = node.getValue();
    if (name.canChangeSignature()) {
      List<DiGraphEdge<Name, Reference>> edges = node.getInEdges();        
      tryEliminateConstantArgs(name, edges);
      tryEliminateOptionalArgs(name, edges);
    }
  }
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //导入依赖的package包/类
/**
 * Removes any optional parameters if no callers specifies it as an argument.
 * @param name The name of the function to optimize. 
 * @param edges All the references to this name.
 */
private void tryEliminateOptionalArgs(Name name,
    List<DiGraphEdge<Name, Reference>> edges) {
  
  // Count the maximum number of arguments passed into this function all
  // all points of the program.
  int maxArgs = -1;

  for (DiGraphEdge<Name, Reference> refEdge : edges) {
    Reference ref = refEdge.getValue();
    Node call = ref.parent;

    if (isCallSite(ref)) {
      int numArgs = call.getChildCount() - 1;
      if (numArgs > maxArgs) {
        maxArgs = numArgs;
      }
    } // else this is a definition or a dereference, ignore it.
  }

  for (Definition definition : name.getDeclarations()) {
    eliminateParamsAfter(definition.getRValue(), maxArgs);
  }
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //导入依赖的package包/类
/**
 * Generate a description of a specific edge between two nodes.
 * For each edge, name the element being linked, the location of the
 * reference in the source file, and the type of the reference.
 *
 * @param builder contents of the report to be generated
 * @param referencedDecl name of the declaration being referenced
 * @param edge the graph edge being described
 */
private void generateEdgeReport(StringBuilder builder,
    Name referencedDecl, DiGraphEdge<Name, Reference> edge) {
  String srcDeclName = referencedDecl.getQualifiedName();
  builder.append("<li><A HREF=\"#" + srcDeclName + "\">");
  builder.append(srcDeclName);
  builder.append("</a> ");

  Node def = edge.getValue().getSite();
  int lineNumber = def.getLineno();
  int columnNumber = def.getCharno();
  String sourceFile = getSourceFile(def);

  generateSourceReferenceLink(builder, sourceFile, lineNumber, columnNumber);

  JSType defType = edge.getValue().getSite().getJSType();
  generateType(builder, defType);
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //导入依赖的package包/类
public int compare(DiGraphNode<Name, Reference> node1,
    DiGraphNode<Name, Reference> node2) {
  Preconditions.checkNotNull(node1.getValue());
  Preconditions.checkNotNull(node2.getValue());

  if ((node1.getValue().getQualifiedName() == null) &&
      (node2.getValue().getQualifiedName() == null)) {
    return 0;
  }

  // Node 1, if null, comes before node 2.
  if (node1.getValue().getQualifiedName() == null) {
    return -1;
  }

  // Node 2, if null, comes before node 1.
  if (node2.getValue().getQualifiedName() == null) {
    return 1;
  }

  return node1.getValue().getQualifiedName().compareTo(
      node2.getValue().getQualifiedName());
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //导入依赖的package包/类
@Override
public void process(Node externs, Node root) {
  if (nameGraph == null) {
    NameReferenceGraphConstruction c =
        new NameReferenceGraphConstruction(compiler);
    c.process(externs, root);
    nameGraph = c.getNameReferenceGraph();
  }

  for (DiGraphNode<Name, Reference> node :
      nameGraph.getDirectedGraphNodes()) {
    Name name = node.getValue();
    if (name.canChangeSignature()) {
      List<DiGraphEdge<Name, Reference>> edges = node.getInEdges();
      tryEliminateConstantArgs(name, edges);
      tryEliminateOptionalArgs(name, edges);
    }
  }
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //导入依赖的package包/类
/**
 * Removes any optional parameters if no callers specifies it as an argument.
 * @param name The name of the function to optimize.
 * @param edges All the references to this name.
 */
private void tryEliminateOptionalArgs(Name name,
    List<DiGraphEdge<Name, Reference>> edges) {

  // Count the maximum number of arguments passed into this function all
  // all points of the program.
  int maxArgs = -1;

  for (DiGraphEdge<Name, Reference> refEdge : edges) {
    Reference ref = refEdge.getValue();
    Node call = ref.parent;

    if (isCallSite(ref)) {
      int numArgs = call.getChildCount() - 1;
      if (numArgs > maxArgs) {
        maxArgs = numArgs;
      }
    } // else this is a definition or a dereference, ignore it.
  }

  for (Definition definition : name.getDeclarations()) {
    eliminateParamsAfter(definition.getRValue(), maxArgs);
  }
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //导入依赖的package包/类
@Override
public int compare(DiGraphNode<Name, Reference> node1,
    DiGraphNode<Name, Reference> node2) {
  Preconditions.checkNotNull(node1.getValue());
  Preconditions.checkNotNull(node2.getValue());

  if ((node1.getValue().getQualifiedName() == null) &&
      (node2.getValue().getQualifiedName() == null)) {
    return 0;
  }

  // Node 1, if null, comes before node 2.
  if (node1.getValue().getQualifiedName() == null) {
    return -1;
  }

  // Node 2, if null, comes before node 1.
  if (node2.getValue().getQualifiedName() == null) {
    return 1;
  }

  return node1.getValue().getQualifiedName().compareTo(
      node2.getValue().getQualifiedName());
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //导入依赖的package包/类
private Reference recordStaticNameUse(
    NodeTraversal t, Node n, Node parent) {
  if (isExtern) {
    // Don't count reference in extern as a use.
    return null;
  } else {
    Reference reference = new Reference(n, parent);
    Name name = graph.defineNameIfNotExists(n.getQualifiedName(), isExtern);
    name.setType(getType(n));
    graph.connect(getNamedContainingFunction(), reference, name);
    return reference;
  }
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //导入依赖的package包/类
private void recordPrototypePropUse(
    NodeTraversal t, Node n, Node parent) {
  Preconditions.checkArgument(NodeUtil.isGetProp(n));
  Node instance = n.getFirstChild();
  JSType instanceType = getType(instance);
  JSType boxedType = instanceType.autoboxesTo();
  instanceType = boxedType != null ? boxedType : instanceType;

  // Retrieves the property.
  ObjectType objType = instanceType.toObjectType();
  Preconditions.checkState(objType != null);

  if (!isExtern) {
    // Don't count reference in extern as a use.
    Reference ref = new Reference(n, parent);

    FunctionType constructor = objType.getConstructor();
    if (constructor != null) {
      String propName = n.getLastChild().getString();
      if (!constructor.getPrototype().hasOwnProperty(propName)) {
        recordSuperClassPrototypePropUse(constructor, propName, ref);
      }

      // TODO(user): TightenType can help a whole lot here.
      recordSubclassPrototypePropUse(constructor, propName, ref);
    } else {
      recordUnknownUse(t, n, parent);
    }
  }
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //导入依赖的package包/类
/**
 * Look for the super class implementation up the tree.
 */
private void recordSuperClassPrototypePropUse(
    FunctionType classType, String prop, Reference ref) {
  FunctionType superClass = classType.getSuperClassConstructor();
  while (superClass != null) {
    if (superClass.getPrototype().hasOwnProperty(prop)) {
      graph.connect(getNamedContainingFunction(), ref,
          graph.defineNameIfNotExists(
             superClass.getReferenceName() + ".prototype." + prop, false));
      return;
    } else {
      superClass = superClass.getSuperClassConstructor();
    }
  }
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //导入依赖的package包/类
/**
 * Conservatively assumes that all subclass implementation of this property
 * might be called.
 */
private void recordSubclassPrototypePropUse(
    FunctionType classType, String prop, Reference ref) {
  if (classType.getPrototype().hasOwnProperty(prop)) {
    graph.connect(getNamedContainingFunction(), ref,
       graph.defineNameIfNotExists(
           classType.getReferenceName() + ".prototype." + prop, false));
  }
  if (classType.getSubTypes() != null) {
    for (FunctionType subclass : classType.getSubTypes()) {
        recordSubclassPrototypePropUse(subclass, prop, ref);
    }
  }
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //导入依赖的package包/类
private void recordUnknownUse(NodeTraversal t, Node n, Node parent) {
  if (isExtern) {
    // Don't count reference in extern as a use.
    return;
  } else {
    Preconditions.checkArgument(NodeUtil.isGetProp(n));
    Reference ref = new Reference(n, parent);
    ref.setUnknown(true);
    unknownNameUse.put(n.getLastChild().getString(),
        new NameUse(getNamedContainingFunction(), ref));
  }
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //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.NameReferenceGraph.Reference; //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.NameReferenceGraph.Reference; //导入依赖的package包/类
/**
 * @param ref A reference to a function.
 * @return true, if it's safe to optimize this function. 
 */
private boolean isCallSite(Reference ref) {
  Node call = ref.parent;
  // We need to make sure we're dealing with a call to the function we're 
  // optimizing. If the the first child of the parent is not the site, this
  // is a nested call and it's a call to another function. 
  return isCallOrNew(call) && call.getFirstChild() == ref.site;
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //导入依赖的package包/类
@Override
public void process(Node externs, Node root) {
  NameReferenceGraphConstruction gc =
      new NameReferenceGraphConstruction(compiler);
  gc.process(externs, root);
  graph = gc.getNameReferenceGraph();
  FixedPointGraphTraversal<Name, Reference> t =
      FixedPointGraphTraversal.newTraversal(new PropagateReferences());
  getInfo(graph.MAIN).markReference(null);
  t.computeFixedPoint(graph, Sets.newHashSet(graph.MAIN));
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //导入依赖的package包/类
public boolean traverseEdge(Name start, Reference edge, Name dest) {
  NameInfo startInfo = getInfo(start);
  NameInfo destInfo = getInfo(dest);
  if (startInfo.isReferenced()) {
    JSModule startModule = startInfo.getDeepestCommonModuleRef();
    if (startModule != null &&
        moduleGraph.dependsOn(startModule, edge.getModule())) {
      return destInfo.markReference(startModule);
    } else {
      return destInfo.markReference(edge.getModule());
    }
  }
  return false;
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //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.NameReferenceGraph.Reference; //导入依赖的package包/类
/**
 * Generate the HTML for describing a specific declaration.
 * @param builder  contents of report to be generated
 * @param declarationNode declaration to describe
 */
private void generateDeclarationReport(StringBuilder builder,
    DiGraphNode<Name, Reference> declarationNode) {
  // Provide the name and location of declaration,
  // with an anchor to allow navigation to this declaration.
  String declName = declarationNode.getValue().getQualifiedName();
  JSType declType = declarationNode.getValue().getType();

  builder.append("<LI> ");
  builder.append("<A NAME=\"" + declName + "\">");
  builder.append(declName);
  builder.append("\n");

  // Provide the type of the declaration.
  // This is helpful for debugging.
  generateType(builder, declType);

  // List all the definitions of this name that were found in the code.
  // For each, list
  List<DefinitionsRemover.Definition> defs =
      declarationNode.getValue().getDeclarations();

  if (defs.size() == 0) {
     builder.append("<br>No definitions found<br>");
  } else {
    // Otherwise, provide a list of definitions in a dotted list.
    // For each definition, print the location where that definition is
    // found.
    builder.append("<ul>");
    for (DefinitionsRemover.Definition def : defs) {
      Node fnDef = def.getRValue();
      String sourceFileName = getSourceFile(fnDef);
      builder.append("<li> Defined: ");
      generateSourceReferenceLink(builder,
          sourceFileName, fnDef.getLineno(), fnDef.getCharno());
    }
    builder.append("</ul>");
  }
}
 

import com.google.javascript.jscomp.NameReferenceGraph.Reference; //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);
      }
    }
  }
}