com.tangosol.internal.util.graal.js.JavaScriptModuleManager Maven / Gradle / Ivy
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/*
* Copyright (c) 2000, 2020, Oracle and/or its affiliates.
*
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
package com.tangosol.internal.util.graal.js;
import com.tangosol.util.ScriptException;
import com.tangosol.internal.util.graal.ScriptDescriptor;
import com.tangosol.internal.util.graal.ScriptManager;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.json.Json;
import javax.json.stream.JsonParser;
import org.graalvm.polyglot.Context;
import org.graalvm.polyglot.Value;
/**
* JavaScriptModuleManager manages loading of JavaScript files. Each JavaScript
* file is considered a module (just as in Node.js).
*
* Each JavaScript file that is loaded is represented by a {@link Module}.
* This class also maintains a cache of loaded modules.
*
* @author mk 2019.07.26
* @since 14.1.1.0
*/
public class JavaScriptModuleManager
{
// ----- constructors ----------------------------------------------------
private JavaScriptModuleManager()
{
}
// ----- JavaScriptModuleManager methods --------------------------------
/**
* Load the specified module. This is the method that is called when a
* JavaScript code calls the {@code require("module-name")} method.
*
* @param sModuleName the name of the module to load
*
* @return the module's exported Object
*/
public synchronized Object require(String sModuleName)
{
Module result;
if (sModuleName.startsWith("./") || sModuleName.startsWith("/") || sModuleName.startsWith("../"))
{
ScriptDescriptor descriptor = getParent().getDescriptor().resolve(sModuleName);
result = loadAsFile(descriptor);
if (result == null)
{
result = loadAsDirectory(descriptor);
}
}
else
{
result = loadAsNodeModule(sModuleName);
}
if (result != null)
{
f_cachedModules.put(result.getDescriptor().getScriptUrl().toString(), result);
getParent().addDependentModule(result);
return result.getExports();
}
throw new ScriptException("Cannot load module: " + sModuleName);
}
/**
* Attempt to load the specified Path as a file by trying to load it as
* 1. specified file,
* 2. as .js or
* 3. as .json file in that order.
*
* @param desc the descriptor
*
* @return the loaded {@link Module}
*
* @throws ScriptException if the script specified in the descriptor
* cannot be found or loaded
*/
private Module loadAsFile(ScriptDescriptor desc)
throws ScriptException
{
for (String extn : new String[] {"", ".js", ".mjs", ".json"})
{
String resourceName = desc.getSimpleName() + extn;
ScriptDescriptor descriptor = desc.resolve(resourceName);
if (descriptor.exists() && !descriptor.isDirectory())
{
return createAndLoadModule(descriptor);
}
}
return null;
}
/**
* Attempt to load this module (file) by treating the specified name as
* directory. Then, within that directory, try to load the package.json
* whose main field (if any) will tell the file name to use.
*
* If no package.json or main field doesn't exist, then try to
* load the index file
*
* @param module the {@link Module}
*
* @return the loaded {@link Module} or {@code null}
*/
private Module loadAsDirectory(ScriptDescriptor module)
{
ScriptDescriptor descriptor = module.resolve("package.json");
if (descriptor.exists() && !descriptor.isDirectory())
{
String mainField = getMainFieldFromJSON(descriptor.getScriptUrl());
if (mainField != null)
{
ScriptDescriptor mainFieldDesc = module.resolve(mainField);
Module m = loadAsFile(mainFieldDesc);
if (m != null)
{
return m;
}
// If no package.json or main field doesn't exist, then try to
// load the index file.
m = loadIndex(module);
if (m != null)
{
return m;
}
}
}
return loadIndex(module);
}
/**
* Load the specified module as a NodeJS module.
*
* @param sModuleName the module name
*
* @return the loaded {@link Module} or {@code null}
*/
private Module loadAsNodeModule(String sModuleName)
{
Module result = null;
for (ScriptDescriptor nodeModulesDir : toNodeModulesPaths(getParent().getDescriptor()))
{
ScriptDescriptor desc = nodeModulesDir.resolve(sModuleName);
result = loadAsFile(desc);
if (result == null)
{
result = loadAsDirectory(desc);
}
if (result != null)
{
break;
}
}
return result;
}
/**
* Load index.js or index.json. Use the specified module as a directory
* and try to load index.js in that directory. If not found then try to
* load index.json in that directory.
*
* @param module the {@link Module}
*
* @return the loaded {@link Module} or {@code null}
*
* @throws ScriptException if index.js or index.json file exists but
* couldn't be loaded
*/
private Module loadIndex(ScriptDescriptor module)
{
for (String indexFileName : new String[] {"index.js", "index.json"})
{
ScriptDescriptor descriptor = module.resolve(indexFileName);
if (descriptor.exists() && !descriptor.isDirectory())
{
return createAndLoadModule(descriptor);
}
}
return null;
}
/**
* Parse the 'package.json' file (whose URL is specified in the parameter.
*
* @param pkgJsonUrl the {@link URL} of the package.json file
*
* @return the value of the {@code main} if it exists in the json file
* or {@code null}
*/
public String getMainFieldFromJSON(URL pkgJsonUrl)
{
String mainFieldValue = null;
int level = 0;
boolean inMainField = false;
try (InputStream is = pkgJsonUrl.openStream();
JsonParser parser = Json.createParser(is))
{
while (parser.hasNext())
{
final JsonParser.Event event = parser.next();
switch (event)
{
case START_OBJECT:
level++;
break;
case END_OBJECT:
level--;
break;
case KEY_NAME:
inMainField = "main".equals(parser.getString());
break;
case VALUE_STRING:
String string = parser.getString();
if (level == 1 && inMainField)
{
mainFieldValue = string;
}
break;
default:
if (inMainField)
{
throw new IllegalStateException("main field value specified but it is not a string");
}
}
}
}
catch (IOException ioEx)
{
throw new ScriptException("Error while parsing: " + pkgJsonUrl);
}
return mainFieldValue;
}
/**
* Get the parent Module.
*
* @return the parent {@link Module}
*/
private Module getParent()
{
return f_partialModules.peekLast();
}
/**
* Create and load the {@link Module} for the
* specified {@link ScriptDescriptor}.
*
* @param descriptor the descriptor for which a {@link Module} needs to
* be created
*
* @return {@link Module} for the specified descriptor
*
* @throws ScriptException if the script specified in the descriptor
* is not found
*/
/*package*/
Module createAndLoadModule(ScriptDescriptor descriptor)
throws ScriptException
{
if (!descriptor.exists())
{
throw new IllegalArgumentException("specified script does not exist. Descriptor: " + descriptor);
}
if (descriptor.isDirectory())
{
throw new IllegalArgumentException("script path must point to a file. Descriptor: " + descriptor);
}
String cachingKey = descriptor.getScriptUrl().toString();
Module module = f_cachedModules.get(cachingKey);
if (module != null)
{
return module;
}
Context context = ScriptManager.getInstance().getContext();
try
{
module = new Module(descriptor);
// This allows cycles in `require()`
f_cachedModules.put(cachingKey, module);
f_partialModules.addLast(module);
setupContextForModule(context, module);
module.load(context);
getParent().addDependentModule(module);
}
finally
{
Module prevModule = f_partialModules.pollLast();
setupContextForModule(context, prevModule);
}
return module;
}
/**
* Get all the node_modules directory walking up the tree from the specified
* directory the root of the tree.
*
* @param base the base {@link ScriptDescriptor}
*
* @return an array of {@link ScriptDescriptor} one for each node modules
* directory
*/
public List toNodeModulesPaths(ScriptDescriptor base)
{
ArrayList dirs = new ArrayList<>();
for(ScriptDescriptor current = base.getParentDescriptor(); current != null; current = current.getParentDescriptor())
{
if (!current.getSimpleName().equals("node_modules"))
{
dirs.add(current.resolve("node_modules/"));
}
}
return dirs;
}
/**
* Return a {@link Map} cached modules where the keys are url of the module
* and values are the {@link Module} objects.
*
* @return a {@link Map} cached modules where the keys are url of the module
* and values are the {@link Module} objects
*/
public HashMap getCachedModules()
{
return f_cachedModules;
}
// ----- JavaScriptModuleManager class methods----------------------------
/**
* Return the singleton {@link JavaScriptModuleManager}.
*
* @return the singleton {@link JavaScriptModuleManager}
*/
public static JavaScriptModuleManager getInstance()
{
return INSTANCE;
}
// ----- helpers ---------------------------------------------------------
/**
* Set up the {@link Context} with {@link Module} specific bindings.
*
* @param context the {@link Context} to setup
* @param module the {@link Module} object
*/
private void setupContextForModule(Context context, Module module)
{
Value bindings = context.getBindings("js");
if (module != null)
{
bindings.putMember("module", module);
bindings.putMember("exports", module.getExports());
bindings.putMember("__dirname", module.getDescriptor().getDirectory());
bindings.putMember("__filename", module.getDescriptor().getScriptPath());
bindings.putMember("require", JavaScriptHandler.getRequireFunction());
}
else
{
bindings.removeMember("module");
bindings.removeMember("exports");
bindings.removeMember("__filename");
bindings.removeMember("__dirname");
bindings.removeMember("require");
}
}
// ----- data members ----------------------------------------------------
/**
* The singleton instance.
*/
private static final JavaScriptModuleManager INSTANCE = new JavaScriptModuleManager();
/**
* The chain of {@link Module}s being loaded. Implemented using a {@link
* Deque} with the last element being the top of the stack. The last element
* is the {@link Module} that is currently being loaded.
*/
private final ArrayDeque f_partialModules = new ArrayDeque<>();
/**
* Map of script url to loaded modules.
*/
private final HashMap f_cachedModules = new HashMap<>();
}