| /* |
| * Copyright (c) 2008, 2012, 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.invoke; |
| |
| import sun.invoke.util.Wrapper; |
| import java.lang.ref.WeakReference; |
| import java.lang.ref.ReferenceQueue; |
| import java.util.Arrays; |
| import java.util.Collections; |
| import java.util.List; |
| import sun.invoke.util.BytecodeDescriptor; |
| import static java.lang.invoke.MethodHandleStatics.*; |
| import sun.invoke.util.VerifyType; |
| |
| /** |
| * A method type represents the arguments and return type accepted and |
| * returned by a method handle, or the arguments and return type passed |
| * and expected by a method handle caller. Method types must be properly |
| * matched between a method handle and all its callers, |
| * and the JVM's operations enforce this matching at, specifically |
| * during calls to {@link MethodHandle#invokeExact MethodHandle.invokeExact} |
| * and {@link MethodHandle#invoke MethodHandle.invoke}, and during execution |
| * of {@code invokedynamic} instructions. |
| * <p> |
| * The structure is a return type accompanied by any number of parameter types. |
| * The types (primitive, {@code void}, and reference) are represented by {@link Class} objects. |
| * (For ease of exposition, we treat {@code void} as if it were a type. |
| * In fact, it denotes the absence of a return type.) |
| * <p> |
| * All instances of {@code MethodType} are immutable. |
| * Two instances are completely interchangeable if they compare equal. |
| * Equality depends on pairwise correspondence of the return and parameter types and on nothing else. |
| * <p> |
| * This type can be created only by factory methods. |
| * All factory methods may cache values, though caching is not guaranteed. |
| * Some factory methods are static, while others are virtual methods which |
| * modify precursor method types, e.g., by changing a selected parameter. |
| * <p> |
| * Factory methods which operate on groups of parameter types |
| * are systematically presented in two versions, so that both Java arrays and |
| * Java lists can be used to work with groups of parameter types. |
| * The query methods {@code parameterArray} and {@code parameterList} |
| * also provide a choice between arrays and lists. |
| * <p> |
| * {@code MethodType} objects are sometimes derived from bytecode instructions |
| * such as {@code invokedynamic}, specifically from the type descriptor strings associated |
| * with the instructions in a class file's constant pool. |
| * <p> |
| * Like classes and strings, method types can also be represented directly |
| * in a class file's constant pool as constants. |
| * A method type may be loaded by an {@code ldc} instruction which refers |
| * to a suitable {@code CONSTANT_MethodType} constant pool entry. |
| * The entry refers to a {@code CONSTANT_Utf8} spelling for the descriptor string. |
| * For more details, see the <a href="package-summary.html#mtcon">package summary</a>. |
| * <p> |
| * When the JVM materializes a {@code MethodType} from a descriptor string, |
| * all classes named in the descriptor must be accessible, and will be loaded. |
| * (But the classes need not be initialized, as is the case with a {@code CONSTANT_Class}.) |
| * This loading may occur at any time before the {@code MethodType} object is first derived. |
| * @author John Rose, JSR 292 EG |
| */ |
| public final |
| class MethodType implements java.io.Serializable { |
| private static final long serialVersionUID = 292L; // {rtype, {ptype...}} |
| |
| // The rtype and ptypes fields define the structural identity of the method type: |
| private final Class<?> rtype; |
| private final Class<?>[] ptypes; |
| |
| // The remaining fields are caches of various sorts: |
| private MethodTypeForm form; // erased form, plus cached data about primitives |
| private MethodType wrapAlt; // alternative wrapped/unwrapped version |
| private Invokers invokers; // cache of handy higher-order adapters |
| |
| /** |
| * Check the given parameters for validity and store them into the final fields. |
| */ |
| private MethodType(Class<?> rtype, Class<?>[] ptypes) { |
| checkRtype(rtype); |
| checkPtypes(ptypes); |
| this.rtype = rtype; |
| this.ptypes = ptypes; |
| } |
| |
| /*trusted*/ MethodTypeForm form() { return form; } |
| /*trusted*/ Class<?> rtype() { return rtype; } |
| /*trusted*/ Class<?>[] ptypes() { return ptypes; } |
| |
| void setForm(MethodTypeForm f) { form = f; } |
| |
| /** This number, mandated by the JVM spec as 255, |
| * is the maximum number of <em>slots</em> |
| * that any Java method can receive in its argument list. |
| * It limits both JVM signatures and method type objects. |
| * The longest possible invocation will look like |
| * {@code staticMethod(arg1, arg2, ..., arg255)} or |
| * {@code x.virtualMethod(arg1, arg2, ..., arg254)}. |
| */ |
| /*non-public*/ static final int MAX_JVM_ARITY = 255; // this is mandated by the JVM spec. |
| |
| /** This number is the maximum arity of a method handle, 254. |
| * It is derived from the absolute JVM-imposed arity by subtracting one, |
| * which is the slot occupied by the method handle itself at the |
| * beginning of the argument list used to invoke the method handle. |
| * The longest possible invocation will look like |
| * {@code mh.invoke(arg1, arg2, ..., arg254)}. |
| */ |
| // Issue: Should we allow MH.invokeWithArguments to go to the full 255? |
| /*non-public*/ static final int MAX_MH_ARITY = MAX_JVM_ARITY-1; // deduct one for mh receiver |
| |
| /** This number is the maximum arity of a method handle invoker, 253. |
| * It is derived from the absolute JVM-imposed arity by subtracting two, |
| * which are the slots occupied by invoke method handle, and the the |
| * target method handle, which are both at the beginning of the argument |
| * list used to invoke the target method handle. |
| * The longest possible invocation will look like |
| * {@code invokermh.invoke(targetmh, arg1, arg2, ..., arg253)}. |
| */ |
| /*non-public*/ static final int MAX_MH_INVOKER_ARITY = MAX_MH_ARITY-1; // deduct one more for invoker |
| |
| private static void checkRtype(Class<?> rtype) { |
| rtype.equals(rtype); // null check |
| } |
| private static int checkPtype(Class<?> ptype) { |
| ptype.getClass(); //NPE |
| if (ptype == void.class) |
| throw newIllegalArgumentException("parameter type cannot be void"); |
| if (ptype == double.class || ptype == long.class) return 1; |
| return 0; |
| } |
| /** Return number of extra slots (count of long/double args). */ |
| private static int checkPtypes(Class<?>[] ptypes) { |
| int slots = 0; |
| for (Class<?> ptype : ptypes) { |
| slots += checkPtype(ptype); |
| } |
| checkSlotCount(ptypes.length + slots); |
| return slots; |
| } |
| static void checkSlotCount(int count) { |
| assert((MAX_JVM_ARITY & (MAX_JVM_ARITY+1)) == 0); |
| // MAX_JVM_ARITY must be power of 2 minus 1 for following code trick to work: |
| if ((count & MAX_JVM_ARITY) != count) |
| throw newIllegalArgumentException("bad parameter count "+count); |
| } |
| private static IndexOutOfBoundsException newIndexOutOfBoundsException(Object num) { |
| if (num instanceof Integer) num = "bad index: "+num; |
| return new IndexOutOfBoundsException(num.toString()); |
| } |
| |
| static final WeakInternSet internTable = new WeakInternSet(); |
| |
| static final Class<?>[] NO_PTYPES = {}; |
| |
| /** |
| * Finds or creates an instance of the given method type. |
| * @param rtype the return type |
| * @param ptypes the parameter types |
| * @return a method type with the given components |
| * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null |
| * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class} |
| */ |
| public static |
| MethodType methodType(Class<?> rtype, Class<?>[] ptypes) { |
| return makeImpl(rtype, ptypes, false); |
| } |
| |
| /** |
| * Finds or creates a method type with the given components. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * @return a method type with the given components |
| * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null |
| * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class} |
| */ |
| public static |
| MethodType methodType(Class<?> rtype, List<Class<?>> ptypes) { |
| boolean notrust = false; // random List impl. could return evil ptypes array |
| return makeImpl(rtype, listToArray(ptypes), notrust); |
| } |
| |
| private static Class<?>[] listToArray(List<Class<?>> ptypes) { |
| // sanity check the size before the toArray call, since size might be huge |
| checkSlotCount(ptypes.size()); |
| return ptypes.toArray(NO_PTYPES); |
| } |
| |
| /** |
| * Finds or creates a method type with the given components. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * The leading parameter type is prepended to the remaining array. |
| * @return a method type with the given components |
| * @throws NullPointerException if {@code rtype} or {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is null |
| * @throws IllegalArgumentException if {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is {@code void.class} |
| */ |
| public static |
| MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) { |
| Class<?>[] ptypes1 = new Class<?>[1+ptypes.length]; |
| ptypes1[0] = ptype0; |
| System.arraycopy(ptypes, 0, ptypes1, 1, ptypes.length); |
| return makeImpl(rtype, ptypes1, true); |
| } |
| |
| /** |
| * Finds or creates a method type with the given components. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * The resulting method has no parameter types. |
| * @return a method type with the given return value |
| * @throws NullPointerException if {@code rtype} is null |
| */ |
| public static |
| MethodType methodType(Class<?> rtype) { |
| return makeImpl(rtype, NO_PTYPES, true); |
| } |
| |
| /** |
| * Finds or creates a method type with the given components. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * The resulting method has the single given parameter type. |
| * @return a method type with the given return value and parameter type |
| * @throws NullPointerException if {@code rtype} or {@code ptype0} is null |
| * @throws IllegalArgumentException if {@code ptype0} is {@code void.class} |
| */ |
| public static |
| MethodType methodType(Class<?> rtype, Class<?> ptype0) { |
| return makeImpl(rtype, new Class<?>[]{ ptype0 }, true); |
| } |
| |
| /** |
| * Finds or creates a method type with the given components. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * The resulting method has the same parameter types as {@code ptypes}, |
| * and the specified return type. |
| * @throws NullPointerException if {@code rtype} or {@code ptypes} is null |
| */ |
| public static |
| MethodType methodType(Class<?> rtype, MethodType ptypes) { |
| return makeImpl(rtype, ptypes.ptypes, true); |
| } |
| |
| /** |
| * Sole factory method to find or create an interned method type. |
| * @param rtype desired return type |
| * @param ptypes desired parameter types |
| * @param trusted whether the ptypes can be used without cloning |
| * @return the unique method type of the desired structure |
| */ |
| /*trusted*/ static |
| MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted) { |
| if (ptypes.length == 0) { |
| ptypes = NO_PTYPES; trusted = true; |
| } |
| MethodType mt1 = new MethodType(rtype, ptypes); |
| MethodType mt0 = internTable.get(mt1); |
| if (mt0 != null) |
| return mt0; |
| if (!trusted) |
| // defensively copy the array passed in by the user |
| mt1 = new MethodType(rtype, ptypes.clone()); |
| // promote the object to the Real Thing, and reprobe |
| MethodTypeForm form = MethodTypeForm.findForm(mt1); |
| mt1.form = form; |
| return internTable.add(mt1); |
| } |
| private static final MethodType[] objectOnlyTypes = new MethodType[20]; |
| |
| /** |
| * Finds or creates a method type whose components are {@code Object} with an optional trailing {@code Object[]} array. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * All parameters and the return type will be {@code Object}, |
| * except the final array parameter if any, which will be {@code Object[]}. |
| * @param objectArgCount number of parameters (excluding the final array parameter if any) |
| * @param finalArray whether there will be a trailing array parameter, of type {@code Object[]} |
| * @return a generally applicable method type, for all calls of the given fixed argument count and a collected array of further arguments |
| * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 (or 254, if {@code finalArray} is true) |
| * @see #genericMethodType(int) |
| */ |
| public static |
| MethodType genericMethodType(int objectArgCount, boolean finalArray) { |
| MethodType mt; |
| checkSlotCount(objectArgCount); |
| int ivarargs = (!finalArray ? 0 : 1); |
| int ootIndex = objectArgCount*2 + ivarargs; |
| if (ootIndex < objectOnlyTypes.length) { |
| mt = objectOnlyTypes[ootIndex]; |
| if (mt != null) return mt; |
| } |
| Class<?>[] ptypes = new Class<?>[objectArgCount + ivarargs]; |
| Arrays.fill(ptypes, Object.class); |
| if (ivarargs != 0) ptypes[objectArgCount] = Object[].class; |
| mt = makeImpl(Object.class, ptypes, true); |
| if (ootIndex < objectOnlyTypes.length) { |
| objectOnlyTypes[ootIndex] = mt; // cache it here also! |
| } |
| return mt; |
| } |
| |
| /** |
| * Finds or creates a method type whose components are all {@code Object}. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * All parameters and the return type will be Object. |
| * @param objectArgCount number of parameters |
| * @return a generally applicable method type, for all calls of the given argument count |
| * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255 |
| * @see #genericMethodType(int, boolean) |
| */ |
| public static |
| MethodType genericMethodType(int objectArgCount) { |
| return genericMethodType(objectArgCount, false); |
| } |
| |
| /** |
| * Finds or creates a method type with a single different parameter type. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * @param num the index (zero-based) of the parameter type to change |
| * @param nptype a new parameter type to replace the old one with |
| * @return the same type, except with the selected parameter changed |
| * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()} |
| * @throws IllegalArgumentException if {@code nptype} is {@code void.class} |
| * @throws NullPointerException if {@code nptype} is null |
| */ |
| public MethodType changeParameterType(int num, Class<?> nptype) { |
| if (parameterType(num) == nptype) return this; |
| checkPtype(nptype); |
| Class<?>[] nptypes = ptypes.clone(); |
| nptypes[num] = nptype; |
| return makeImpl(rtype, nptypes, true); |
| } |
| |
| /** |
| * Finds or creates a method type with additional parameter types. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * @param num the position (zero-based) of the inserted parameter type(s) |
| * @param ptypesToInsert zero or more new parameter types to insert into the parameter list |
| * @return the same type, except with the selected parameter(s) inserted |
| * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()} |
| * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} |
| * or if the resulting method type would have more than 255 parameter slots |
| * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null |
| */ |
| public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) { |
| int len = ptypes.length; |
| if (num < 0 || num > len) |
| throw newIndexOutOfBoundsException(num); |
| int ins = checkPtypes(ptypesToInsert); |
| checkSlotCount(parameterSlotCount() + ptypesToInsert.length + ins); |
| int ilen = ptypesToInsert.length; |
| if (ilen == 0) return this; |
| Class<?>[] nptypes = Arrays.copyOfRange(ptypes, 0, len+ilen); |
| System.arraycopy(nptypes, num, nptypes, num+ilen, len-num); |
| System.arraycopy(ptypesToInsert, 0, nptypes, num, ilen); |
| return makeImpl(rtype, nptypes, true); |
| } |
| |
| /** |
| * Finds or creates a method type with additional parameter types. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list |
| * @return the same type, except with the selected parameter(s) appended |
| * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} |
| * or if the resulting method type would have more than 255 parameter slots |
| * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null |
| */ |
| public MethodType appendParameterTypes(Class<?>... ptypesToInsert) { |
| return insertParameterTypes(parameterCount(), ptypesToInsert); |
| } |
| |
| /** |
| * Finds or creates a method type with additional parameter types. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * @param num the position (zero-based) of the inserted parameter type(s) |
| * @param ptypesToInsert zero or more new parameter types to insert into the parameter list |
| * @return the same type, except with the selected parameter(s) inserted |
| * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()} |
| * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} |
| * or if the resulting method type would have more than 255 parameter slots |
| * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null |
| */ |
| public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) { |
| return insertParameterTypes(num, listToArray(ptypesToInsert)); |
| } |
| |
| /** |
| * Finds or creates a method type with additional parameter types. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list |
| * @return the same type, except with the selected parameter(s) appended |
| * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} |
| * or if the resulting method type would have more than 255 parameter slots |
| * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null |
| */ |
| public MethodType appendParameterTypes(List<Class<?>> ptypesToInsert) { |
| return insertParameterTypes(parameterCount(), ptypesToInsert); |
| } |
| |
| /** |
| * Finds or creates a method type with modified parameter types. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * @param start the position (zero-based) of the first replaced parameter type(s) |
| * @param end the position (zero-based) after the last replaced parameter type(s) |
| * @param ptypesToInsert zero or more new parameter types to insert into the parameter list |
| * @return the same type, except with the selected parameter(s) replaced |
| * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()} |
| * or if {@code end} is negative or greater than {@code parameterCount()} |
| * or if {@code start} is greater than {@code end} |
| * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class} |
| * or if the resulting method type would have more than 255 parameter slots |
| * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null |
| */ |
| /*non-public*/ MethodType replaceParameterTypes(int start, int end, Class<?>... ptypesToInsert) { |
| if (start == end) |
| return insertParameterTypes(start, ptypesToInsert); |
| int len = ptypes.length; |
| if (!(0 <= start && start <= end && end <= len)) |
| throw newIndexOutOfBoundsException("start="+start+" end="+end); |
| int ilen = ptypesToInsert.length; |
| if (ilen == 0) |
| return dropParameterTypes(start, end); |
| return dropParameterTypes(start, end).insertParameterTypes(start, ptypesToInsert); |
| } |
| |
| /** |
| * Finds or creates a method type with some parameter types omitted. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * @param start the index (zero-based) of the first parameter type to remove |
| * @param end the index (greater than {@code start}) of the first parameter type after not to remove |
| * @return the same type, except with the selected parameter(s) removed |
| * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()} |
| * or if {@code end} is negative or greater than {@code parameterCount()} |
| * or if {@code start} is greater than {@code end} |
| */ |
| public MethodType dropParameterTypes(int start, int end) { |
| int len = ptypes.length; |
| if (!(0 <= start && start <= end && end <= len)) |
| throw newIndexOutOfBoundsException("start="+start+" end="+end); |
| if (start == end) return this; |
| Class<?>[] nptypes; |
| if (start == 0) { |
| if (end == len) { |
| // drop all parameters |
| nptypes = NO_PTYPES; |
| } else { |
| // drop initial parameter(s) |
| nptypes = Arrays.copyOfRange(ptypes, end, len); |
| } |
| } else { |
| if (end == len) { |
| // drop trailing parameter(s) |
| nptypes = Arrays.copyOfRange(ptypes, 0, start); |
| } else { |
| int tail = len - end; |
| nptypes = Arrays.copyOfRange(ptypes, 0, start + tail); |
| System.arraycopy(ptypes, end, nptypes, start, tail); |
| } |
| } |
| return makeImpl(rtype, nptypes, true); |
| } |
| |
| /** |
| * Finds or creates a method type with a different return type. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * @param nrtype a return parameter type to replace the old one with |
| * @return the same type, except with the return type change |
| * @throws NullPointerException if {@code nrtype} is null |
| */ |
| public MethodType changeReturnType(Class<?> nrtype) { |
| if (returnType() == nrtype) return this; |
| return makeImpl(nrtype, ptypes, true); |
| } |
| |
| /** |
| * Reports if this type contains a primitive argument or return value. |
| * The return type {@code void} counts as a primitive. |
| * @return true if any of the types are primitives |
| */ |
| public boolean hasPrimitives() { |
| return form.hasPrimitives(); |
| } |
| |
| /** |
| * Reports if this type contains a wrapper argument or return value. |
| * Wrappers are types which box primitive values, such as {@link Integer}. |
| * The reference type {@code java.lang.Void} counts as a wrapper, |
| * if it occurs as a return type. |
| * @return true if any of the types are wrappers |
| */ |
| public boolean hasWrappers() { |
| return unwrap() != this; |
| } |
| |
| /** |
| * Erases all reference types to {@code Object}. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * All primitive types (including {@code void}) will remain unchanged. |
| * @return a version of the original type with all reference types replaced |
| */ |
| public MethodType erase() { |
| return form.erasedType(); |
| } |
| |
| /** |
| * Erases all reference types to {@code Object}, and all subword types to {@code int}. |
| * This is the reduced type polymorphism used by private methods |
| * such as {@link MethodHandle#invokeBasic invokeBasic}. |
| * @return a version of the original type with all reference and subword types replaced |
| */ |
| /*non-public*/ MethodType basicType() { |
| return form.basicType(); |
| } |
| |
| /** |
| * @return a version of the original type with MethodHandle prepended as the first argument |
| */ |
| /*non-public*/ MethodType invokerType() { |
| return insertParameterTypes(0, MethodHandle.class); |
| } |
| |
| /** |
| * Converts all types, both reference and primitive, to {@code Object}. |
| * Convenience method for {@link #genericMethodType(int) genericMethodType}. |
| * The expression {@code type.wrap().erase()} produces the same value |
| * as {@code type.generic()}. |
| * @return a version of the original type with all types replaced |
| */ |
| public MethodType generic() { |
| return genericMethodType(parameterCount()); |
| } |
| |
| /** |
| * Converts all primitive types to their corresponding wrapper types. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * All reference types (including wrapper types) will remain unchanged. |
| * A {@code void} return type is changed to the type {@code java.lang.Void}. |
| * The expression {@code type.wrap().erase()} produces the same value |
| * as {@code type.generic()}. |
| * @return a version of the original type with all primitive types replaced |
| */ |
| public MethodType wrap() { |
| return hasPrimitives() ? wrapWithPrims(this) : this; |
| } |
| |
| /** |
| * Converts all wrapper types to their corresponding primitive types. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * All primitive types (including {@code void}) will remain unchanged. |
| * A return type of {@code java.lang.Void} is changed to {@code void}. |
| * @return a version of the original type with all wrapper types replaced |
| */ |
| public MethodType unwrap() { |
| MethodType noprims = !hasPrimitives() ? this : wrapWithPrims(this); |
| return unwrapWithNoPrims(noprims); |
| } |
| |
| private static MethodType wrapWithPrims(MethodType pt) { |
| assert(pt.hasPrimitives()); |
| MethodType wt = pt.wrapAlt; |
| if (wt == null) { |
| // fill in lazily |
| wt = MethodTypeForm.canonicalize(pt, MethodTypeForm.WRAP, MethodTypeForm.WRAP); |
| assert(wt != null); |
| pt.wrapAlt = wt; |
| } |
| return wt; |
| } |
| |
| private static MethodType unwrapWithNoPrims(MethodType wt) { |
| assert(!wt.hasPrimitives()); |
| MethodType uwt = wt.wrapAlt; |
| if (uwt == null) { |
| // fill in lazily |
| uwt = MethodTypeForm.canonicalize(wt, MethodTypeForm.UNWRAP, MethodTypeForm.UNWRAP); |
| if (uwt == null) |
| uwt = wt; // type has no wrappers or prims at all |
| wt.wrapAlt = uwt; |
| } |
| return uwt; |
| } |
| |
| /** |
| * Returns the parameter type at the specified index, within this method type. |
| * @param num the index (zero-based) of the desired parameter type |
| * @return the selected parameter type |
| * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()} |
| */ |
| public Class<?> parameterType(int num) { |
| return ptypes[num]; |
| } |
| /** |
| * Returns the number of parameter types in this method type. |
| * @return the number of parameter types |
| */ |
| public int parameterCount() { |
| return ptypes.length; |
| } |
| /** |
| * Returns the return type of this method type. |
| * @return the return type |
| */ |
| public Class<?> returnType() { |
| return rtype; |
| } |
| |
| /** |
| * Presents the parameter types as a list (a convenience method). |
| * The list will be immutable. |
| * @return the parameter types (as an immutable list) |
| */ |
| public List<Class<?>> parameterList() { |
| return Collections.unmodifiableList(Arrays.asList(ptypes)); |
| } |
| |
| /*non-public*/ Class<?> lastParameterType() { |
| int len = ptypes.length; |
| return len == 0 ? void.class : ptypes[len-1]; |
| } |
| |
| /** |
| * Presents the parameter types as an array (a convenience method). |
| * Changes to the array will not result in changes to the type. |
| * @return the parameter types (as a fresh copy if necessary) |
| */ |
| public Class<?>[] parameterArray() { |
| return ptypes.clone(); |
| } |
| |
| /** |
| * Compares the specified object with this type for equality. |
| * That is, it returns <tt>true</tt> if and only if the specified object |
| * is also a method type with exactly the same parameters and return type. |
| * @param x object to compare |
| * @see Object#equals(Object) |
| */ |
| @Override |
| public boolean equals(Object x) { |
| return this == x || x instanceof MethodType && equals((MethodType)x); |
| } |
| |
| private boolean equals(MethodType that) { |
| return this.rtype == that.rtype |
| && Arrays.equals(this.ptypes, that.ptypes); |
| } |
| |
| /** |
| * Returns the hash code value for this method type. |
| * It is defined to be the same as the hashcode of a List |
| * whose elements are the return type followed by the |
| * parameter types. |
| * @return the hash code value for this method type |
| * @see Object#hashCode() |
| * @see #equals(Object) |
| * @see List#hashCode() |
| */ |
| @Override |
| public int hashCode() { |
| int hashCode = 31 + rtype.hashCode(); |
| for (Class<?> ptype : ptypes) |
| hashCode = 31*hashCode + ptype.hashCode(); |
| return hashCode; |
| } |
| |
| /** |
| * Returns a string representation of the method type, |
| * of the form {@code "(PT0,PT1...)RT"}. |
| * The string representation of a method type is a |
| * parenthesis enclosed, comma separated list of type names, |
| * followed immediately by the return type. |
| * <p> |
| * Each type is represented by its |
| * {@link java.lang.Class#getSimpleName simple name}. |
| */ |
| @Override |
| public String toString() { |
| StringBuilder sb = new StringBuilder(); |
| sb.append("("); |
| for (int i = 0; i < ptypes.length; i++) { |
| if (i > 0) sb.append(","); |
| sb.append(ptypes[i].getSimpleName()); |
| } |
| sb.append(")"); |
| sb.append(rtype.getSimpleName()); |
| return sb.toString(); |
| } |
| |
| |
| /*non-public*/ |
| boolean isViewableAs(MethodType newType) { |
| if (!VerifyType.isNullConversion(returnType(), newType.returnType())) |
| return false; |
| int argc = parameterCount(); |
| if (argc != newType.parameterCount()) |
| return false; |
| for (int i = 0; i < argc; i++) { |
| if (!VerifyType.isNullConversion(newType.parameterType(i), parameterType(i))) |
| return false; |
| } |
| return true; |
| } |
| /*non-public*/ |
| boolean isCastableTo(MethodType newType) { |
| int argc = parameterCount(); |
| if (argc != newType.parameterCount()) |
| return false; |
| return true; |
| } |
| /*non-public*/ |
| boolean isConvertibleTo(MethodType newType) { |
| if (!canConvert(returnType(), newType.returnType())) |
| return false; |
| int argc = parameterCount(); |
| if (argc != newType.parameterCount()) |
| return false; |
| for (int i = 0; i < argc; i++) { |
| if (!canConvert(newType.parameterType(i), parameterType(i))) |
| return false; |
| } |
| return true; |
| } |
| /*non-public*/ |
| static boolean canConvert(Class<?> src, Class<?> dst) { |
| // short-circuit a few cases: |
| if (src == dst || dst == Object.class) return true; |
| // the remainder of this logic is documented in MethodHandle.asType |
| if (src.isPrimitive()) { |
| // can force void to an explicit null, a la reflect.Method.invoke |
| // can also force void to a primitive zero, by analogy |
| if (src == void.class) return true; //or !dst.isPrimitive()? |
| Wrapper sw = Wrapper.forPrimitiveType(src); |
| if (dst.isPrimitive()) { |
| // P->P must widen |
| return Wrapper.forPrimitiveType(dst).isConvertibleFrom(sw); |
| } else { |
| // P->R must box and widen |
| return dst.isAssignableFrom(sw.wrapperType()); |
| } |
| } else if (dst.isPrimitive()) { |
| // any value can be dropped |
| if (dst == void.class) return true; |
| Wrapper dw = Wrapper.forPrimitiveType(dst); |
| // R->P must be able to unbox (from a dynamically chosen type) and widen |
| // For example: |
| // Byte/Number/Comparable/Object -> dw:Byte -> byte. |
| // Character/Comparable/Object -> dw:Character -> char |
| // Boolean/Comparable/Object -> dw:Boolean -> boolean |
| // This means that dw must be cast-compatible with src. |
| if (src.isAssignableFrom(dw.wrapperType())) { |
| return true; |
| } |
| // The above does not work if the source reference is strongly typed |
| // to a wrapper whose primitive must be widened. For example: |
| // Byte -> unbox:byte -> short/int/long/float/double |
| // Character -> unbox:char -> int/long/float/double |
| if (Wrapper.isWrapperType(src) && |
| dw.isConvertibleFrom(Wrapper.forWrapperType(src))) { |
| // can unbox from src and then widen to dst |
| return true; |
| } |
| // We have already covered cases which arise due to runtime unboxing |
| // of a reference type which covers several wrapper types: |
| // Object -> cast:Integer -> unbox:int -> long/float/double |
| // Serializable -> cast:Byte -> unbox:byte -> byte/short/int/long/float/double |
| // An marginal case is Number -> dw:Character -> char, which would be OK if there were a |
| // subclass of Number which wraps a value that can convert to char. |
| // Since there is none, we don't need an extra check here to cover char or boolean. |
| return false; |
| } else { |
| // R->R always works, since null is always valid dynamically |
| return true; |
| } |
| } |
| |
| /// Queries which have to do with the bytecode architecture |
| |
| /** Reports the number of JVM stack slots required to invoke a method |
| * of this type. Note that (for historical reasons) the JVM requires |
| * a second stack slot to pass long and double arguments. |
| * So this method returns {@link #parameterCount() parameterCount} plus the |
| * number of long and double parameters (if any). |
| * <p> |
| * This method is included for the benfit of applications that must |
| * generate bytecodes that process method handles and invokedynamic. |
| * @return the number of JVM stack slots for this type's parameters |
| */ |
| /*non-public*/ int parameterSlotCount() { |
| return form.parameterSlotCount(); |
| } |
| |
| /*non-public*/ Invokers invokers() { |
| Invokers inv = invokers; |
| if (inv != null) return inv; |
| invokers = inv = new Invokers(this); |
| return inv; |
| } |
| |
| /** Reports the number of JVM stack slots which carry all parameters including and after |
| * the given position, which must be in the range of 0 to |
| * {@code parameterCount} inclusive. Successive parameters are |
| * more shallowly stacked, and parameters are indexed in the bytecodes |
| * according to their trailing edge. Thus, to obtain the depth |
| * in the outgoing call stack of parameter {@code N}, obtain |
| * the {@code parameterSlotDepth} of its trailing edge |
| * at position {@code N+1}. |
| * <p> |
| * Parameters of type {@code long} and {@code double} occupy |
| * two stack slots (for historical reasons) and all others occupy one. |
| * Therefore, the number returned is the number of arguments |
| * <em>including</em> and <em>after</em> the given parameter, |
| * <em>plus</em> the number of long or double arguments |
| * at or after after the argument for the given parameter. |
| * <p> |
| * This method is included for the benfit of applications that must |
| * generate bytecodes that process method handles and invokedynamic. |
| * @param num an index (zero-based, inclusive) within the parameter types |
| * @return the index of the (shallowest) JVM stack slot transmitting the |
| * given parameter |
| * @throws IllegalArgumentException if {@code num} is negative or greater than {@code parameterCount()} |
| */ |
| /*non-public*/ int parameterSlotDepth(int num) { |
| if (num < 0 || num > ptypes.length) |
| parameterType(num); // force a range check |
| return form.parameterToArgSlot(num-1); |
| } |
| |
| /** Reports the number of JVM stack slots required to receive a return value |
| * from a method of this type. |
| * If the {@link #returnType() return type} is void, it will be zero, |
| * else if the return type is long or double, it will be two, else one. |
| * <p> |
| * This method is included for the benfit of applications that must |
| * generate bytecodes that process method handles and invokedynamic. |
| * @return the number of JVM stack slots (0, 1, or 2) for this type's return value |
| * Will be removed for PFD. |
| */ |
| /*non-public*/ int returnSlotCount() { |
| return form.returnSlotCount(); |
| } |
| |
| /** |
| * Finds or creates an instance of a method type, given the spelling of its bytecode descriptor. |
| * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}. |
| * Any class or interface name embedded in the descriptor string |
| * will be resolved by calling {@link ClassLoader#loadClass(java.lang.String)} |
| * on the given loader (or if it is null, on the system class loader). |
| * <p> |
| * Note that it is possible to encounter method types which cannot be |
| * constructed by this method, because their component types are |
| * not all reachable from a common class loader. |
| * <p> |
| * This method is included for the benfit of applications that must |
| * generate bytecodes that process method handles and {@code invokedynamic}. |
| * @param descriptor a bytecode-level type descriptor string "(T...)T" |
| * @param loader the class loader in which to look up the types |
| * @return a method type matching the bytecode-level type descriptor |
| * @throws NullPointerException if the string is null |
| * @throws IllegalArgumentException if the string is not well-formed |
| * @throws TypeNotPresentException if a named type cannot be found |
| */ |
| public static MethodType fromMethodDescriptorString(String descriptor, ClassLoader loader) |
| throws IllegalArgumentException, TypeNotPresentException |
| { |
| if (!descriptor.startsWith("(") || // also generates NPE if needed |
| descriptor.indexOf(')') < 0 || |
| descriptor.indexOf('.') >= 0) |
| throw new IllegalArgumentException("not a method descriptor: "+descriptor); |
| List<Class<?>> types = BytecodeDescriptor.parseMethod(descriptor, loader); |
| Class<?> rtype = types.remove(types.size() - 1); |
| checkSlotCount(types.size()); |
| Class<?>[] ptypes = listToArray(types); |
| return makeImpl(rtype, ptypes, true); |
| } |
| |
| /** |
| * Produces a bytecode descriptor representation of the method type. |
| * <p> |
| * Note that this is not a strict inverse of {@link #fromMethodDescriptorString fromMethodDescriptorString}. |
| * Two distinct classes which share a common name but have different class loaders |
| * will appear identical when viewed within descriptor strings. |
| * <p> |
| * This method is included for the benfit of applications that must |
| * generate bytecodes that process method handles and {@code invokedynamic}. |
| * {@link #fromMethodDescriptorString(java.lang.String, java.lang.ClassLoader) fromMethodDescriptorString}, |
| * because the latter requires a suitable class loader argument. |
| * @return the bytecode type descriptor representation |
| */ |
| public String toMethodDescriptorString() { |
| return BytecodeDescriptor.unparse(this); |
| } |
| |
| /*non-public*/ static String toFieldDescriptorString(Class<?> cls) { |
| return BytecodeDescriptor.unparse(cls); |
| } |
| |
| /// Serialization. |
| |
| /** |
| * There are no serializable fields for {@code MethodType}. |
| */ |
| private static final java.io.ObjectStreamField[] serialPersistentFields = { }; |
| |
| /** |
| * Save the {@code MethodType} instance to a stream. |
| * |
| * @serialData |
| * For portability, the serialized format does not refer to named fields. |
| * Instead, the return type and parameter type arrays are written directly |
| * from the {@code writeObject} method, using two calls to {@code s.writeObject} |
| * as follows: |
| * <blockquote><pre> |
| s.writeObject(this.returnType()); |
| s.writeObject(this.parameterArray()); |
| * </pre></blockquote> |
| * <p> |
| * The deserialized field values are checked as if they were |
| * provided to the factory method {@link #methodType(Class,Class[]) methodType}. |
| * For example, null values, or {@code void} parameter types, |
| * will lead to exceptions during deserialization. |
| * @param the stream to write the object to |
| */ |
| private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException { |
| s.defaultWriteObject(); // requires serialPersistentFields to be an empty array |
| s.writeObject(returnType()); |
| s.writeObject(parameterArray()); |
| } |
| |
| /** |
| * Reconstitute the {@code MethodType} instance from a stream (that is, |
| * deserialize it). |
| * This instance is a scratch object with bogus final fields. |
| * It provides the parameters to the factory method called by |
| * {@link #readResolve readResolve}. |
| * After that call it is discarded. |
| * @param the stream to read the object from |
| * @see #MethodType() |
| * @see #readResolve |
| * @see #writeObject |
| */ |
| private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException { |
| s.defaultReadObject(); // requires serialPersistentFields to be an empty array |
| |
| Class<?> returnType = (Class<?>) s.readObject(); |
| Class<?>[] parameterArray = (Class<?>[]) s.readObject(); |
| |
| // Probably this object will never escape, but let's check |
| // the field values now, just to be sure. |
| checkRtype(returnType); |
| checkPtypes(parameterArray); |
| |
| parameterArray = parameterArray.clone(); // make sure it is unshared |
| MethodType_init(returnType, parameterArray); |
| } |
| |
| /** |
| * For serialization only. |
| * Sets the final fields to null, pending {@code Unsafe.putObject}. |
| */ |
| private MethodType() { |
| this.rtype = null; |
| this.ptypes = null; |
| } |
| private void MethodType_init(Class<?> rtype, Class<?>[] ptypes) { |
| // In order to communicate these values to readResolve, we must |
| // store them into the implementation-specific final fields. |
| checkRtype(rtype); |
| checkPtypes(ptypes); |
| UNSAFE.putObject(this, rtypeOffset, rtype); |
| UNSAFE.putObject(this, ptypesOffset, ptypes); |
| } |
| |
| // Support for resetting final fields while deserializing |
| private static final long rtypeOffset, ptypesOffset; |
| static { |
| try { |
| rtypeOffset = UNSAFE.objectFieldOffset |
| (MethodType.class.getDeclaredField("rtype")); |
| ptypesOffset = UNSAFE.objectFieldOffset |
| (MethodType.class.getDeclaredField("ptypes")); |
| } catch (Exception ex) { |
| throw new Error(ex); |
| } |
| } |
| |
| /** |
| * Resolves and initializes a {@code MethodType} object |
| * after serialization. |
| * @return the fully initialized {@code MethodType} object |
| */ |
| private Object readResolve() { |
| // Do not use a trusted path for deserialization: |
| //return makeImpl(rtype, ptypes, true); |
| // Verify all operands, and make sure ptypes is unshared: |
| return methodType(rtype, ptypes); |
| } |
| |
| /** |
| * Weak intern set based on implementation of the <tt>HashSet</tt> and |
| * <tt>WeakHashMap</tt>, with <em>weak values</em>. Note: <tt>null</tt> |
| * values will yield <tt>NullPointerException</tt> |
| * Refer to implementation of WeakInternSet for details. |
| * |
| * @see java.util.HashMap |
| * @see java.util.HashSet |
| * @see java.util.WeakHashMap |
| * @see java.lang.ref.WeakReference |
| */ |
| private static class WeakInternSet { |
| // The default initial capacity -- MUST be a power of two. |
| private static final int DEFAULT_INITIAL_CAPACITY = 16; |
| |
| // The maximum capacity, used if a higher value is implicitly specified |
| // by either of the constructors with arguments. |
| // MUST be a power of two <= 1<<30. |
| private static final int MAXIMUM_CAPACITY = 1 << 30; |
| |
| // The load factor used when none specified in constructor. |
| private static final float DEFAULT_LOAD_FACTOR = 0.75f; |
| |
| // The table, resized as necessary. Length MUST Always be a power of two. |
| private Entry[] table; |
| |
| // The number of entries contained in this set. |
| private int size; |
| |
| // The next size value at which to resize (capacity * load factor). |
| private int threshold; |
| |
| // The load factor for the hash table. |
| private final float loadFactor; |
| |
| // Reference queue for cleared WeakEntries |
| private final ReferenceQueue<Object> queue = new ReferenceQueue<>(); |
| |
| private Entry[] newTable(int n) { |
| return new Entry[n]; |
| } |
| |
| /** |
| * Constructs a new, empty <tt>WeakInternSet</tt> with the default initial |
| * capacity (16) and load factor (0.75). |
| */ |
| WeakInternSet() { |
| this.loadFactor = DEFAULT_LOAD_FACTOR; |
| threshold = DEFAULT_INITIAL_CAPACITY; |
| table = newTable(DEFAULT_INITIAL_CAPACITY); |
| } |
| |
| /** |
| * Applies a supplemental hash function to a given hashCode, which |
| * defends against poor quality hash functions. This is critical |
| * because hashing uses power-of-two length hash tables, that |
| * otherwise encounter collisions for hashCodes that do not differ |
| * in lower bits. |
| * @param h preliminary hash code value |
| * @return supplemental hash code value |
| */ |
| private static int hash(int h) { |
| // This function ensures that hashCodes that differ only by |
| // constant multiples at each bit position have a bounded |
| // number of collisions (approximately 8 at default load factor). |
| h ^= (h >>> 20) ^ (h >>> 12); |
| return h ^ (h >>> 7) ^ (h >>> 4); |
| } |
| |
| /** |
| * Checks for equality of non-null reference x and possibly-null y. By |
| * default uses Object.equals. |
| * @param x first object to compare |
| * @param y second object to compare |
| * @return <tt>true</tt> if objects are equal |
| */ |
| private static boolean eq(Object x, Object y) { |
| return x == y || x.equals(y); |
| } |
| |
| /** |
| * Returns index for hash code h. |
| * @param h raw hash code |
| * @param length length of table (power of 2) |
| * @return index in table |
| */ |
| private static int indexFor(int h, int length) { |
| return h & (length-1); |
| } |
| |
| /** |
| * Expunges stale entries from the table. |
| */ |
| private void expungeStaleEntries() { |
| for (Object x; (x = queue.poll()) != null; ) { |
| synchronized (queue) { |
| Entry entry = (Entry) x; |
| int i = indexFor(entry.hash, table.length); |
| Entry prev = table[i]; |
| Entry p = prev; |
| while (p != null) { |
| Entry next = p.next; |
| if (p == entry) { |
| if (prev == entry) |
| table[i] = next; |
| else |
| prev.next = next; |
| entry.next = null; |
| size--; |
| break; |
| } |
| prev = p; |
| p = next; |
| } |
| } |
| } |
| } |
| |
| /** |
| * Returns the table after first expunging stale entries. |
| * @return an expunged hash table |
| */ |
| private Entry[] getTable() { |
| expungeStaleEntries(); |
| return table; |
| } |
| |
| /** |
| * Returns the entry to which the specified value is mapped, |
| * or {@code null} if this set contains no entry for the value. |
| * |
| * <p>More formally, if this set contains an entry for value |
| * {@code entry} to a value {@code value} such that |
| * {@code entry.equals(value)}, then this method returns {@code entry}; |
| * otherwise it returns {@code null}. |
| * |
| * @param value value to search for in set |
| * @return interned value if in set, otherwise <tt>null</tt> |
| */ |
| synchronized MethodType get(MethodType value) { |
| int h = hash(value.hashCode()); |
| Entry[] tab = getTable(); |
| int index = indexFor(h, tab.length); |
| Entry e = tab[index]; |
| MethodType g; |
| while (e != null) { |
| if (e.hash == h && eq(value, g = e.get())) |
| return g; |
| e = e.next; |
| } |
| return null; |
| } |
| |
| /** |
| * Attempts to add the specified value to the set and returns same value. |
| * If the set previously contained an entry for this value, the old |
| * value is left untouched and returned as the result. |
| * |
| * @param value value to be added |
| * @return the previous entry associated with <tt>value</tt>, or |
| * <tt>value</tt> if there was no previous entry found |
| */ |
| synchronized MethodType add(MethodType value) { |
| int h = hash(value.hashCode()); |
| Entry[] tab = getTable(); |
| int i = indexFor(h, tab.length); |
| MethodType g; |
| for (Entry e = tab[i]; e != null; e = e.next) { |
| if (h == e.hash && eq(value, g = e.get())) { |
| return g; |
| } |
| } |
| Entry e = tab[i]; |
| tab[i] = new Entry(value, queue, h, e); |
| if (++size >= threshold) |
| resize(tab.length * 2); |
| return value; |
| } |
| |
| /** |
| * Rehashes the contents of this set into a new array with a |
| * larger capacity. This method is called automatically when the |
| * number of keys in this set reaches its threshold. |
| * |
| * If current capacity is MAXIMUM_CAPACITY, this method does not |
| * resize the set, but sets threshold to Integer.MAX_VALUE. |
| * This has the effect of preventing future calls. |
| * |
| * @param newCapacity the new capacity, MUST be a power of two; |
| * must be greater than current capacity unless current |
| * capacity is MAXIMUM_CAPACITY (in which case value |
| * is irrelevant) |
| */ |
| private void resize(int newCapacity) { |
| Entry[] oldTable = getTable(); |
| int oldCapacity = oldTable.length; |
| if (oldCapacity == MAXIMUM_CAPACITY) { |
| threshold = Integer.MAX_VALUE; |
| return; |
| } |
| |
| Entry[] newTable = newTable(newCapacity); |
| transfer(oldTable, newTable); |
| table = newTable; |
| |
| /* |
| * If ignoring null elements and processing ref queue caused massive |
| * shrinkage, then restore old table. This should be rare, but avoids |
| * unbounded expansion of garbage-filled tables. |
| */ |
| if (size >= threshold / 2) { |
| threshold = (int)(newCapacity * loadFactor); |
| } else { |
| expungeStaleEntries(); |
| transfer(newTable, oldTable); |
| table = oldTable; |
| } |
| } |
| |
| /** |
| * Transfers all entries from src to dest tables |
| * @param src original table |
| * @param dest new table |
| */ |
| private void transfer(Entry[] src, Entry[] dest) { |
| for (int j = 0; j < src.length; ++j) { |
| Entry e = src[j]; |
| src[j] = null; |
| while (e != null) { |
| Entry next = e.next; |
| MethodType key = e.get(); |
| if (key == null) { |
| e.next = null; // Help GC |
| size--; |
| } else { |
| int i = indexFor(e.hash, dest.length); |
| e.next = dest[i]; |
| dest[i] = e; |
| } |
| e = next; |
| } |
| } |
| } |
| |
| /** |
| * The entries in this hash table extend WeakReference, using its main ref |
| * field as the key. |
| */ |
| private static class Entry extends WeakReference<MethodType> { |
| final int hash; |
| Entry next; |
| |
| /** |
| * Creates new entry. |
| */ |
| Entry(MethodType key, |
| ReferenceQueue<Object> queue, |
| int hash, Entry next) { |
| super(key, queue); |
| this.hash = hash; |
| this.next = next; |
| } |
| } |
| } |
| } |
