/*
- * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
 
 package java.lang;
 
+import jdk.internal.loader.BuiltinClassLoader;
+import jdk.internal.misc.VM;
+import jdk.internal.module.ModuleHashes;
+import jdk.internal.module.ModuleReferenceImpl;
+
+import java.lang.module.ModuleDescriptor.Version;
+import java.lang.module.ModuleReference;
+import java.lang.module.ResolvedModule;
+import java.util.HashSet;
 import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
 
 /**
  * An element in a stack trace, as returned by {@link
  * Throwable#getStackTrace()}.  Each element represents a single stack frame.
  * All stack frames except for the one at the top of the stack represent
  * a method invocation.  The frame at the top of the stack represents the
  * execution point at which the stack trace was generated.  Typically,
  * this is the point at which the throwable corresponding to the stack trace
  * was created.
  *
  * @since  1.4
  * @author Josh Bloch
  */
 public final class StackTraceElement implements java.io.Serializable {
-    // Normally initialized by VM (public constructor added in 1.5)
+
+    // For Throwables and StackWalker, the VM initially sets this field to a
+    // reference to the declaring Class.  The Class reference is used to
+    // construct the 'format' bitmap, and then is cleared.
+    //
+    // For STEs constructed using the public constructors, this field is not used.
+    private transient Class<?> declaringClassObject;
+
+    // Normally initialized by VM
+    private String classLoaderName;
+    private String moduleName;
+    private String moduleVersion;
     private String declaringClass;
     private String methodName;
     private String fileName;
     private int    lineNumber;
+    private byte   format = 0; // Default to show all
 
     /**
      * Creates a stack trace element representing the specified execution
-     * point.
+     * point. The {@link #getModuleName module name} and {@link
+     * #getModuleVersion module version} of the stack trace element will
+     * be {@code null}.
      *
      * @param declaringClass the fully qualified name of the class containing
      *        the execution point represented by the stack trace element
      * @param methodName the name of the method containing the execution point
      *        represented by the stack trace element
      * @param fileName the name of the file containing the execution point
      *         represented by the stack trace element, or {@code null} if
      *         this information is unavailable
      * @param lineNumber the line number of the source line containing the
      *         execution point represented by this stack trace element, or
      *         a negative number if this information is unavailable. A value
      *         of -2 indicates that the method containing the execution point
      *         is a native method
      * @throws NullPointerException if {@code declaringClass} or
      *         {@code methodName} is null
      * @since 1.5
+     * @revised 9
+     * @spec JPMS
      */
     public StackTraceElement(String declaringClass, String methodName,
                              String fileName, int lineNumber) {
-        this.declaringClass = Objects.requireNonNull(declaringClass, "Declaring class is null");
-        this.methodName     = Objects.requireNonNull(methodName, "Method name is null");
-        this.fileName       = fileName;
-        this.lineNumber     = lineNumber;
+        this(null, null, null, declaringClass, methodName, fileName, lineNumber);
     }
 
     /**
+     * Creates a stack trace element representing the specified execution
+     * point.
+     *
+     * @param classLoaderName the class loader name if the class loader of
+     *        the class containing the execution point represented by
+     *        the stack trace is named; otherwise {@code null}
+     * @param moduleName the module name if the class containing the
+     *        execution point represented by the stack trace is in a named
+     *        module; otherwise {@code null}
+     * @param moduleVersion the module version if the class containing the
+     *        execution point represented by the stack trace is in a named
+     *        module that has a version; otherwise {@code null}
+     * @param declaringClass the fully qualified name of the class containing
+     *        the execution point represented by the stack trace element
+     * @param methodName the name of the method containing the execution point
+     *        represented by the stack trace element
+     * @param fileName the name of the file containing the execution point
+     *        represented by the stack trace element, or {@code null} if
+     *        this information is unavailable
+     * @param lineNumber the line number of the source line containing the
+     *        execution point represented by this stack trace element, or
+     *        a negative number if this information is unavailable. A value
+     *        of -2 indicates that the method containing the execution point
+     *        is a native method
+     *
+     * @throws NullPointerException if {@code declaringClass} is {@code null}
+     *         or {@code methodName} is {@code null}
+     *
+     * @since 9
+     * @spec JPMS
+     */
+    public StackTraceElement(String classLoaderName,
+                             String moduleName, String moduleVersion,
+                             String declaringClass, String methodName,
+                             String fileName, int lineNumber) {
+        this.classLoaderName = classLoaderName;
+        this.moduleName      = moduleName;
+        this.moduleVersion   = moduleVersion;
+        this.declaringClass  = Objects.requireNonNull(declaringClass, "Declaring class is null");
+        this.methodName      = Objects.requireNonNull(methodName, "Method name is null");
+        this.fileName        = fileName;
+        this.lineNumber      = lineNumber;
+    }
+
+    /*
+     * Private constructor for the factory methods to create StackTraceElement
+     * for Throwable and StackFrameInfo
+     */
+    private StackTraceElement() {}
+
+    /**
      * Returns the name of the source file containing the execution point
      * represented by this stack trace element.  Generally, this corresponds
      * to the {@code SourceFile} attribute of the relevant {@code class}
      * file (as per <i>The Java Virtual Machine Specification</i>, Section
      * 4.7.7).  In some systems, the name may refer to some source code unit
      * other than a file, such as an entry in source repository.
      *
      * @return the name of the file containing the execution point
      *         represented by this stack trace element, or {@code null} if
      *         this information is unavailable.
      */
     public String getFileName() {
         return fileName;
     }
 
     /**
      * Returns the line number of the source line containing the execution
      * point represented by this stack trace element.  Generally, this is
      * derived from the {@code LineNumberTable} attribute of the relevant
      * {@code class} file (as per <i>The Java Virtual Machine
      * Specification</i>, Section 4.7.8).
      *
      * @return the line number of the source line containing the execution
      *         point represented by this stack trace element, or a negative
      *         number if this information is unavailable.
      */
     public int getLineNumber() {
         return lineNumber;
     }
 
     /**
+     * Returns the module name of the module containing the execution point
+     * represented by this stack trace element.
+     *
+     * @return the module name of the {@code Module} containing the execution
+     *         point represented by this stack trace element; {@code null}
+     *         if the module name is not available.
+     * @since 9
+     * @spec JPMS
+     * @see Module#getName()
+     */
+    public String getModuleName() {
+        return moduleName;
+    }
+
+    /**
+     * Returns the module version of the module containing the execution point
+     * represented by this stack trace element.
+     *
+     * @return the module version of the {@code Module} containing the execution
+     *         point represented by this stack trace element; {@code null}
+     *         if the module version is not available.
+     * @since 9
+     * @spec JPMS
+     * @see java.lang.module.ModuleDescriptor.Version
+     */
+    public String getModuleVersion() {
+        return moduleVersion;
+    }
+
+    /**
+     * Returns the name of the class loader of the class containing the
+     * execution point represented by this stack trace element.
+     *
+     * @return the name of the class loader of the class containing the execution
+     *         point represented by this stack trace element; {@code null}
+     *         if the class loader is not named.
+     *
+     * @since 9
+     * @spec JPMS
+     * @see java.lang.ClassLoader#getName()
+     */
+    public String getClassLoaderName() {
+        return classLoaderName;
+    }
+
+    /**
      * Returns the fully qualified name of the class containing the
      * execution point represented by this stack trace element.
      *
      * @return the fully qualified name of the {@code Class} containing
      *         the execution point represented by this stack trace element.
      */
     public String getClassName() {
         return declaringClass;
     }
 
     /**
      * Returns the name of the method containing the execution point
      * represented by this stack trace element.  If the execution point is
      * contained in an instance or class initializer, this method will return
      * the appropriate <i>special method name</i>, {@code <init>} or
      * {@code <clinit>}, as per Section 3.9 of <i>The Java Virtual
      * Machine Specification</i>.
      *
      * @return the name of the method containing the execution point
      *         represented by this stack trace element.
      */
     public String getMethodName() {
         return methodName;
     }
 
     /**
      * Returns true if the method containing the execution point
      * represented by this stack trace element is a native method.
      *
      * @return {@code true} if the method containing the execution point
      *         represented by this stack trace element is a native method.
      */
     public boolean isNativeMethod() {
         return lineNumber == -2;
     }
 
     /**
-     * Returns a string representation of this stack trace element.  The
-     * format of this string depends on the implementation, but the following
-     * examples may be regarded as typical:
+     * Returns a string representation of this stack trace element.
+     *
+     * @apiNote The format of this string depends on the implementation, but the
+     * following examples may be regarded as typical:
      * <ul>
      * <li>
-     *   {@code "MyClass.mash(MyClass.java:9)"} - Here, {@code "MyClass"}
-     *   is the <i>fully-qualified name</i> of the class containing the
-     *   execution point represented by this stack trace element,
-     *   {@code "mash"} is the name of the method containing the execution
-     *   point, {@code "MyClass.java"} is the source file containing the
-     *   execution point, and {@code "9"} is the line number of the source
-     *   line containing the execution point.
+     *     "{@code com.foo.loader/foo@9.0/com.foo.Main.run(Main.java:101)}"
+     * - See the description below.
+     * </li>
      * <li>
-     *   {@code "MyClass.mash(MyClass.java)"} - As above, but the line
-     *   number is unavailable.
+     *     "{@code com.foo.loader/foo@9.0/com.foo.Main.run(Main.java)}"
+     * - The line number is unavailable.
+     * </li>
      * <li>
-     *   {@code "MyClass.mash(Unknown Source)"} - As above, but neither
-     *   the file name nor the line  number are available.
+     *     "{@code com.foo.loader/foo@9.0/com.foo.Main.run(Unknown Source)}"
+     * - Neither the file name nor the line number is available.
+     * </li>
      * <li>
-     *   {@code "MyClass.mash(Native Method)"} - As above, but neither
-     *   the file name nor the line  number are available, and the method
-     *   containing the execution point is known to be a native method.
+     *     "{@code com.foo.loader/foo@9.0/com.foo.Main.run(Native Method)}"
+     * - The method containing the execution point is a native method.
+     * </li>
+     * <li>
+     *     "{@code com.foo.loader//com.foo.bar.App.run(App.java:12)}"
+     * - The class of the execution point is defined in the unnamed module of
+     * the class loader named {@code com.foo.loader}.
+     * </li>
+     * <li>
+     *     "{@code acme@2.1/org.acme.Lib.test(Lib.java:80)}"
+     * - The class of the execution point is defined in {@code acme} module
+     * loaded by a built-in class loader such as the application class loader.
+     * </li>
+     * <li>
+     *     "{@code MyClass.mash(MyClass.java:9)}"
+     * - {@code MyClass} class is on the application class path.
+     * </li>
      * </ul>
+     *
+     * <p> The first example shows a stack trace element consisting of
+     * three elements, each separated by {@code "/"} followed with
+     * the source file name and the line number of the source line
+     * containing the execution point.
+     *
+     * The first element "{@code com.foo.loader}" is
+     * the name of the class loader.  The second element "{@code foo@9.0}"
+     * is the module name and version.  The third element is the method
+     * containing the execution point; "{@code com.foo.Main"}" is the
+     * fully-qualified class name and "{@code run}" is the name of the method.
+     * "{@code Main.java}" is the source file name and "{@code 101}" is
+     * the line number.
+     *
+     * <p> If a class is defined in an <em>unnamed module</em>
+     * then the second element is omitted as shown in
+     * "{@code com.foo.loader//com.foo.bar.App.run(App.java:12)}".
+     *
+     * <p> If the class loader is a <a href="ClassLoader.html#builtinLoaders">
+     * built-in class loader</a> or is not named then the first element
+     * and its following {@code "/"} are omitted as shown in
+     * "{@code acme@2.1/org.acme.Lib.test(Lib.java:80)}".
+     * If the first element is omitted and the module is an unnamed module,
+     * the second element and its following {@code "/"} are also omitted
+     * as shown in "{@code MyClass.mash(MyClass.java:9)}".
+     *
+     * <p> The {@code toString} method may return two different values on two
+     * {@code StackTraceElement} instances that are
+     * {@linkplain #equals(Object) equal}, for example one created via the
+     * constructor, and one obtained from {@link java.lang.Throwable} or
+     * {@link java.lang.StackWalker.StackFrame}, where an implementation may
+     * choose to omit some element in the returned string.
+     *
+     * @revised 9
+     * @spec JPMS
      * @see    Throwable#printStackTrace()
      */
     public String toString() {
-        return getClassName() + "." + methodName +
-            (isNativeMethod() ? "(Native Method)" :
-             (fileName != null && lineNumber >= 0 ?
-              "(" + fileName + ":" + lineNumber + ")" :
-              (fileName != null ?  "("+fileName+")" : "(Unknown Source)")));
+        String s = "";
+        if (!dropClassLoaderName() && classLoaderName != null &&
+                !classLoaderName.isEmpty()) {
+            s += classLoaderName + "/";
+        }
+        if (moduleName != null && !moduleName.isEmpty()) {
+            s += moduleName;
+
+            if (!dropModuleVersion() && moduleVersion != null &&
+                    !moduleVersion.isEmpty()) {
+                s += "@" + moduleVersion;
+            }
+        }
+        s = s.isEmpty() ? declaringClass : s + "/" + declaringClass;
+
+        return s + "." + methodName + "(" +
+             (isNativeMethod() ? "Native Method)" :
+              (fileName != null && lineNumber >= 0 ?
+               fileName + ":" + lineNumber + ")" :
+                (fileName != null ?  ""+fileName+")" : "Unknown Source)")));
     }
 
     /**
      * Returns true if the specified object is another
      * {@code StackTraceElement} instance representing the same execution
      * point as this instance.  Two stack trace elements {@code a} and
      * {@code b} are equal if and only if:
      * <pre>{@code
-     *     equals(a.getFileName(), b.getFileName()) &&
-     *     a.getLineNumber() == b.getLineNumber()) &&
+     *     equals(a.getClassLoaderName(), b.getClassLoaderName()) &&
+     *     equals(a.getModuleName(), b.getModuleName()) &&
+     *     equals(a.getModuleVersion(), b.getModuleVersion()) &&
      *     equals(a.getClassName(), b.getClassName()) &&
      *     equals(a.getMethodName(), b.getMethodName())
+     *     equals(a.getFileName(), b.getFileName()) &&
+     *     a.getLineNumber() == b.getLineNumber()
+     *
      * }</pre>
      * where {@code equals} has the semantics of {@link
      * java.util.Objects#equals(Object, Object) Objects.equals}.
      *
      * @param  obj the object to be compared with this stack trace element.
      * @return true if the specified object is another
      *         {@code StackTraceElement} instance representing the same
      *         execution point as this instance.
+     *
+     * @revised 9
+     * @spec JPMS
      */
     public boolean equals(Object obj) {
         if (obj==this)
             return true;
         if (!(obj instanceof StackTraceElement))
             return false;
         StackTraceElement e = (StackTraceElement)obj;
-        return e.declaringClass.equals(declaringClass) &&
+        return Objects.equals(classLoaderName, e.classLoaderName) &&
+            Objects.equals(moduleName, e.moduleName) &&
+            Objects.equals(moduleVersion, e.moduleVersion) &&
+            e.declaringClass.equals(declaringClass) &&
             e.lineNumber == lineNumber &&
             Objects.equals(methodName, e.methodName) &&
             Objects.equals(fileName, e.fileName);
     }
 
     /**
      * Returns a hash code value for this stack trace element.
      */
     public int hashCode() {
         int result = 31*declaringClass.hashCode() + methodName.hashCode();
+        result = 31*result + Objects.hashCode(classLoaderName);
+        result = 31*result + Objects.hashCode(moduleName);
+        result = 31*result + Objects.hashCode(moduleVersion);
         result = 31*result + Objects.hashCode(fileName);
         result = 31*result + lineNumber;
         return result;
     }
 
+
+    /**
+     * Called from of() methods to set the 'format' bitmap using the Class
+     * reference stored in declaringClassObject, and then clear the reference.
+     *
+     * <p>
+     * If the module is a non-upgradeable JDK module, then set
+     * JDK_NON_UPGRADEABLE_MODULE to omit its version string.
+     * <p>
+     * If the loader is one of the built-in loaders (`boot`, `platform`, or `app`)
+     * then set BUILTIN_CLASS_LOADER to omit the first element (`<loader>/`).
+     */
+    private synchronized void computeFormat() {
+        try {
+            Class<?> cls = (Class<?>) declaringClassObject;
+            ClassLoader loader = cls.getClassLoader0();
+            Module m = cls.getModule();
+            byte bits = 0;
+
+            // First element - class loader name
+            // Call package-private ClassLoader::name method
+
+            if (loader instanceof BuiltinClassLoader) {
+                bits |= BUILTIN_CLASS_LOADER;
+            }
+
+            // Second element - module name and version
+
+            // Omit if is a JDK non-upgradeable module (recorded in the hashes
+            // in java.base)
+            if (isHashedInJavaBase(m)) {
+                bits |= JDK_NON_UPGRADEABLE_MODULE;
+            }
+            format = bits;
+        } finally {
+            // Class reference no longer needed, clear it
+            declaringClassObject = null;
+        }
+    }
+
+    private static final byte BUILTIN_CLASS_LOADER       = 0x1;
+    private static final byte JDK_NON_UPGRADEABLE_MODULE = 0x2;
+
+    private boolean dropClassLoaderName() {
+        return (format & BUILTIN_CLASS_LOADER) == BUILTIN_CLASS_LOADER;
+    }
+
+    private boolean dropModuleVersion() {
+        return (format & JDK_NON_UPGRADEABLE_MODULE) == JDK_NON_UPGRADEABLE_MODULE;
+    }
+
+    /**
+     * Returns true if the module is hashed with java.base.
+     * <p>
+     * This method returns false when running on the exploded image
+     * since JDK modules are not hashed. They have no Version attribute
+     * and so "@<version>" part will be omitted anyway.
+     */
+    private static boolean isHashedInJavaBase(Module m) {
+        // return true if module system is not initialized as the code
+        // must be in java.base
+        if (!VM.isModuleSystemInited())
+            return true;
+
+        return ModuleLayer.boot() == m.getLayer() && HashedModules.contains(m);
+    }
+
+    /*
+     * Finds JDK non-upgradeable modules, i.e. the modules that are
+     * included in the hashes in java.base.
+     */
+    private static class HashedModules {
+        static Set<String> HASHED_MODULES = hashedModules();
+
+        static Set<String> hashedModules() {
+
+            Optional<ResolvedModule> resolvedModule = ModuleLayer.boot()
+                    .configuration()
+                    .findModule("java.base");
+            assert resolvedModule.isPresent();
+            ModuleReference mref = resolvedModule.get().reference();
+            assert mref instanceof ModuleReferenceImpl;
+            ModuleHashes hashes = ((ModuleReferenceImpl)mref).recordedHashes();
+            if (hashes != null) {
+                Set<String> names = new HashSet<>(hashes.names());
+                names.add("java.base");
+                return names;
+            }
+
+            return Set.of();
+        }
+
+        static boolean contains(Module m) {
+            return HASHED_MODULES.contains(m.getName());
+        }
+    }
+
+
+    /*
+     * Returns an array of StackTraceElements of the given depth
+     * filled from the backtrace of a given Throwable.
+     */
+    static StackTraceElement[] of(Throwable x, int depth) {
+        StackTraceElement[] stackTrace = new StackTraceElement[depth];
+        for (int i = 0; i < depth; i++) {
+            stackTrace[i] = new StackTraceElement();
+        }
+
+        // VM to fill in StackTraceElement
+        initStackTraceElements(stackTrace, x);
+
+        // ensure the proper StackTraceElement initialization
+        for (StackTraceElement ste : stackTrace) {
+            ste.computeFormat();
+        }
+        return stackTrace;
+    }
+
+    /*
+     * Returns a StackTraceElement from a given StackFrameInfo.
+     */
+    static StackTraceElement of(StackFrameInfo sfi) {
+        StackTraceElement ste = new StackTraceElement();
+        initStackTraceElement(ste, sfi);
+
+        ste.computeFormat();
+        return ste;
+    }
+
+    /*
+     * Sets the given stack trace elements with the backtrace
+     * of the given Throwable.
+     */
+    private static native void initStackTraceElements(StackTraceElement[] elements,
+                                                      Throwable x);
+    /*
+     * Sets the given stack trace element with the given StackFrameInfo
+     */
+    private static native void initStackTraceElement(StackTraceElement element,
+                                                     StackFrameInfo sfi);
+
     private static final long serialVersionUID = 6992337162326171013L;
 }