Adding necessary fake classes to allow Javac to compile lamda expressions against our emulation library.
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26 package java.lang.invoke;
29 * A {@code CallSite} is a holder for a variable {@link MethodHandle},
30 * which is called its {@code target}.
31 * An {@code invokedynamic} instruction linked to a {@code CallSite} delegates
32 * all calls to the site's current target.
33 * A {@code CallSite} may be associated with several {@code invokedynamic}
34 * instructions, or it may be "free floating", associated with none.
35 * In any case, it may be invoked through an associated method handle
36 * called its {@linkplain #dynamicInvoker dynamic invoker}.
38 * {@code CallSite} is an abstract class which does not allow
39 * direct subclassing by users. It has three immediate,
40 * concrete subclasses that may be either instantiated or subclassed.
42 * <li>If a mutable target is not required, an {@code invokedynamic} instruction
43 * may be permanently bound by means of a {@linkplain ConstantCallSite constant call site}.
44 * <li>If a mutable target is required which has volatile variable semantics,
45 * because updates to the target must be immediately and reliably witnessed by other threads,
46 * a {@linkplain VolatileCallSite volatile call site} may be used.
47 * <li>Otherwise, if a mutable target is required,
48 * a {@linkplain MutableCallSite mutable call site} may be used.
51 * A non-constant call site may be <em>relinked</em> by changing its target.
52 * The new target must have the same {@linkplain MethodHandle#type() type}
53 * as the previous target.
54 * Thus, though a call site can be relinked to a series of
55 * successive targets, it cannot change its type.
57 * Here is a sample use of call sites and bootstrap methods which links every
58 * dynamic call site to print its arguments:
59 <blockquote><pre>{@code
60 static void test() throws Throwable {
61 // THE FOLLOWING LINE IS PSEUDOCODE FOR A JVM INSTRUCTION
62 InvokeDynamic[#bootstrapDynamic].baz("baz arg", 2, 3.14);
64 private static void printArgs(Object... args) {
65 System.out.println(java.util.Arrays.deepToString(args));
67 private static final MethodHandle printArgs;
69 MethodHandles.Lookup lookup = MethodHandles.lookup();
70 Class thisClass = lookup.lookupClass(); // (who am I?)
71 printArgs = lookup.findStatic(thisClass,
72 "printArgs", MethodType.methodType(void.class, Object[].class));
74 private static CallSite bootstrapDynamic(MethodHandles.Lookup caller, String name, MethodType type) {
75 // ignore caller and name, but match the type:
76 return new ConstantCallSite(printArgs.asType(type));
79 * @author John Rose, JSR 292 EG
82 public class CallSite {
83 // The actual payload of this call site:
85 MethodHandle target; // Note: This field is known to the JVM. Do not change.
88 * Make a blank call site object with the given method type.
89 * An initial target method is supplied which will throw
90 * an {@link IllegalStateException} if called.
92 * Before this {@code CallSite} object is returned from a bootstrap method,
93 * it is usually provided with a more useful target method,
94 * via a call to {@link CallSite#setTarget(MethodHandle) setTarget}.
95 * @throws NullPointerException if the proposed type is null
98 CallSite(MethodType type) {
99 throw new IllegalStateException();
103 * Make a call site object equipped with an initial target method handle.
104 * @param target the method handle which will be the initial target of the call site
105 * @throws NullPointerException if the proposed target is null
108 CallSite(MethodHandle target) {
109 target.type(); // null check
110 this.target = target;
114 * Make a call site object equipped with an initial target method handle.
115 * @param targetType the desired type of the call site
116 * @param createTargetHook a hook which will bind the call site to the target method handle
117 * @throws WrongMethodTypeException if the hook cannot be invoked on the required arguments,
118 * or if the target returned by the hook is not of the given {@code targetType}
119 * @throws NullPointerException if the hook returns a null value
120 * @throws ClassCastException if the hook returns something other than a {@code MethodHandle}
121 * @throws Throwable anything else thrown by the hook function
124 CallSite(MethodType targetType, MethodHandle createTargetHook) throws Throwable {
125 throw new IllegalStateException();
129 * Returns the type of this call site's target.
130 * Although targets may change, any call site's type is permanent, and can never change to an unequal type.
131 * The {@code setTarget} method enforces this invariant by refusing any new target that does
132 * not have the previous target's type.
133 * @return the type of the current target, which is also the type of any future target
135 public MethodType type() {
136 // warning: do not call getTarget here, because CCS.getTarget can throw IllegalStateException
137 return target.type();
141 * Returns the target method of the call site, according to the
142 * behavior defined by this call site's specific class.
143 * The immediate subclasses of {@code CallSite} document the
144 * class-specific behaviors of this method.
146 * @return the current linkage state of the call site, its target method handle
147 * @see ConstantCallSite
148 * @see VolatileCallSite
150 * @see ConstantCallSite#getTarget
151 * @see MutableCallSite#getTarget
152 * @see VolatileCallSite#getTarget
154 public abstract MethodHandle getTarget();
157 * Updates the target method of this call site, according to the
158 * behavior defined by this call site's specific class.
159 * The immediate subclasses of {@code CallSite} document the
160 * class-specific behaviors of this method.
162 * The type of the new target must be {@linkplain MethodType#equals equal to}
163 * the type of the old target.
165 * @param newTarget the new target
166 * @throws NullPointerException if the proposed new target is null
167 * @throws WrongMethodTypeException if the proposed new target
168 * has a method type that differs from the previous target
169 * @see CallSite#getTarget
170 * @see ConstantCallSite#setTarget
171 * @see MutableCallSite#setTarget
172 * @see VolatileCallSite#setTarget
174 public abstract void setTarget(MethodHandle newTarget);
177 * Produces a method handle equivalent to an invokedynamic instruction
178 * which has been linked to this call site.
180 * This method is equivalent to the following code:
181 * <blockquote><pre>{@code
182 * MethodHandle getTarget, invoker, result;
183 * getTarget = MethodHandles.publicLookup().bind(this, "getTarget", MethodType.methodType(MethodHandle.class));
184 * invoker = MethodHandles.exactInvoker(this.type());
185 * result = MethodHandles.foldArguments(invoker, getTarget)
186 * }</pre></blockquote>
188 * @return a method handle which always invokes this call site's current target
190 public abstract MethodHandle dynamicInvoker();