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Closure Compiler is a JavaScript optimizing compiler. It parses your
JavaScript, analyzes it, removes dead code and rewrites and minimizes
what's left. It also checks syntax, variable references, and types, and
warns about common JavaScript pitfalls. It is used in many of Google's
JavaScript apps, including Gmail, Google Web Search, Google Maps, and
Google Docs.
/*
* Copyright 2007 The Closure Compiler Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.javascript.jscomp;
import com.google.javascript.jscomp.ControlFlowGraph.Branch;
import com.google.javascript.jscomp.graph.DiGraph.DiGraphEdge;
import com.google.javascript.jscomp.graph.DiGraph.DiGraphNode;
import com.google.javascript.jscomp.graph.GraphvizGraph;
import com.google.javascript.jscomp.graph.GraphvizGraph.GraphvizEdge;
import com.google.javascript.jscomp.graph.GraphvizGraph.GraphvizNode;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.jstype.JSType;
import java.io.IOException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
/**
* DotFormatter prints out a dot file of the Abstract Syntax Tree.
* For a detailed description of the dot format and visualization tool refer
* to Graphviz.
* Typical usage of this class
* System.out.println(new DotFormatter().toDot(node));
* This class is not thread safe and should not be used without proper
* external synchronization.
*/
public final class DotFormatter {
private static final String INDENT = " ";
private static final String ARROW = " -> ";
private static final String LINE = " -- ";
// stores the current assignment of node to keys
private final HashMap assignments = new HashMap<>();
// key count in order to assign a unique key to each node
private int keyCount = 0;
// the builder used to generate the dot diagram
private final Appendable builder;
private final ControlFlowGraph cfg;
private final boolean printAnnotations;
/** For Testing Only */
private DotFormatter() {
this.builder = new StringBuilder();
this.cfg = null;
this.printAnnotations = false;
}
private DotFormatter(Node n, ControlFlowGraph cfg,
Appendable builder, boolean printAnnotations) throws IOException {
this.cfg = cfg;
this.builder = builder;
this.printAnnotations = printAnnotations;
formatPreamble();
traverseNodes(n);
formatConclusion();
}
/**
* Converts an AST to dot representation.
* @param n the root of the AST described in the dot formatted string
* @return the dot representation of the AST
*/
public static String toDot(Node n) throws IOException {
return toDot(n, null);
}
/**
* Converts an AST to dot representation.
* @param n the root of the AST described in the dot formatted string
* @param inCFG Control Flow Graph.
* @return the dot representation of the AST
*/
static String toDot(Node n, ControlFlowGraph inCFG)
throws IOException {
StringBuilder builder = new StringBuilder();
new DotFormatter(n, inCFG, builder, false);
return builder.toString();
}
/**
* Outputs a string in DOT format that presents the graph.
*
* @param graph Input graph.
* @return A string in Dot format that presents the graph.
*/
public static String toDot(GraphvizGraph graph) {
StringBuilder builder = new StringBuilder();
builder.append(graph.isDirected() ? "digraph" : "graph");
builder.append(INDENT);
builder.append(graph.getName());
builder.append(" {\n");
builder.append(INDENT);
builder.append("node [color=lightblue2, style=filled];\n");
final String edgeSymbol = graph.isDirected() ? ARROW : LINE;
List nodes = graph.getGraphvizNodes();
String[] nodeNames = new String[nodes.size()];
for (int i = 0; i < nodeNames.length; i++) {
GraphvizNode gNode = nodes.get(i);
nodeNames[i] =
gNode.getId()
+ " [label=\""
+ gNode.getLabel()
+ "\" color=\""
+ gNode.getColor()
+ "\"]";
}
// We sort the nodes so we get a deterministic output every time regardless
// of the implementation of the graph data structure.
Arrays.sort(nodeNames);
for (String nodeName : nodeNames) {
builder.append(INDENT);
builder.append(nodeName);
builder.append(";\n");
}
List edges = graph.getGraphvizEdges();
String[] edgeNames = new String[edges.size()];
for (int i = 0; i < edgeNames.length; i++) {
GraphvizEdge edge = edges.get(i);
edgeNames[i] = edge.getNode1Id() + edgeSymbol + edge.getNode2Id();
}
// Again, we sort the edges as well.
Arrays.sort(edgeNames);
for (String edgeName : edgeNames) {
builder.append(INDENT);
builder.append(edgeName);
builder.append(";\n");
}
builder.append("}\n");
return builder.toString();
}
/**
* Converts an AST to dot representation and appends it to the given buffer.
* @param n the root of the AST described in the dot formatted string
* @param inCFG Control Flow Graph.
* @param builder A place to dump the graph.
*/
static void appendDot(Node n, ControlFlowGraph inCFG,
Appendable builder) throws IOException {
new DotFormatter(n, inCFG, builder, false);
}
/**
* Creates a DotFormatter purely for testing DotFormatter's internal methods.
*/
static DotFormatter newInstanceForTesting() {
return new DotFormatter();
}
private void traverseNodes(Node parent) throws IOException {
// key
int keyParent = key(parent);
// edges
for (Node child = parent.getFirstChild(); child != null;
child = child.getNext()) {
int keyChild = key(child);
builder.append(INDENT);
builder.append(formatNodeName(keyParent));
builder.append(ARROW);
builder.append(formatNodeName(keyChild));
builder.append(" [weight=1];\n");
traverseNodes(child);
}
// Flow Edges
if (cfg != null && cfg.hasNode(parent)) {
List> outEdges =
cfg.getOutEdges(parent);
String[] edgeList = new String[outEdges.size()];
for (int i = 0; i < edgeList.length; i++) {
DiGraphEdge edge = outEdges.get(i);
DiGraphNode succ = edge.getDestination();
String toNode = null;
if (succ == cfg.getImplicitReturn()) {
toNode = "RETURN";
} else {
int keySucc = key(succ.getValue());
toNode = formatNodeName(keySucc);
}
edgeList[i] =
formatNodeName(keyParent) + ARROW + toNode + " [label=\"" + edge.getValue() + "\", "
+ "fontcolor=\"red\", "
+ "weight=0.01, color=\"red\"];\n";
}
Arrays.sort(edgeList);
for (String element : edgeList) {
builder.append(INDENT);
builder.append(element);
}
}
}
int key(Node n) throws IOException {
Integer key = assignments.get(n);
if (key == null) {
key = keyCount++;
assignments.put(n, key);
builder.append(INDENT);
builder.append(formatNodeName(key));
builder.append(" [label=\"");
builder.append(n.getToken().toString());
JSType type = n.getJSType();
if (type != null) {
builder.append(" : ");
builder.append(type.toString());
}
if (printAnnotations && cfg != null && cfg.hasNode(n)) {
Object annotation = cfg.getNode(n).getAnnotation();
if (annotation != null) {
builder.append("\\n");
builder.append(annotation.toString());
}
}
builder.append("\"");
if (n.getJSDocInfo() != null) {
builder.append(" color=\"green\"");
}
builder.append("];\n");
}
return key;
}
private static String formatNodeName(Integer key) {
return "node" + key;
}
private void formatPreamble() throws IOException {
builder.append("digraph AST {\n");
builder.append(INDENT);
builder.append("node [color=lightblue2, style=filled];\n");
}
private void formatConclusion() throws IOException {
builder.append("}\n");
}
}