java.lang.invoke.MethodHandle.asFixedArity()方法的使用及代码示例

x33g5p2x  于2022-01-24 转载在 其他  
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本文整理了Java中java.lang.invoke.MethodHandle.asFixedArity()方法的一些代码示例，展示了MethodHandle.asFixedArity()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。MethodHandle.asFixedArity()方法的具体详情如下：
包路径：java.lang.invoke.MethodHandle
类名称：MethodHandle
方法名：asFixedArity

MethodHandle.asFixedArity介绍

[英]Makes a fixed arity method handle which is otherwise equivalent to the current method handle.

If the current method handle is not of #asVarargsCollector, the current method handle is returned. This is true even if the current method handle could not be a valid input to asVarargsCollector.

Otherwise, the resulting fixed-arity method handle has the same type and behavior of the current method handle, except that #isVarargsCollectorwill be false. The fixed-arity method handle may (or may not) be the a previous argument to asVarargsCollector.

Here is an example, of a list-making variable arity method handle:

  1. MethodHandle asListVar = publicLookup()try { asListFix.invoke((Object)1); } 
  2. catch (Exception ex) { caught = ex; } 
  3. assert(caught instanceof ClassCastException); 
  4. assertEquals("[two, too]", asListVar.invoke("two", "too").toString()); 
  5. try { asListFix.invoke("two", "too"); } 
  6. catch (Exception ex) { caught = ex; } 
  7. assert(caught instanceof WrongMethodTypeException); 
  8. Object[] argv = { "three", "thee", "tee" }; 
  9. assertEquals("[three, thee, tee]", asListVar.invoke(argv).toString()); 
  10. assertEquals("[three, thee, tee]", asListFix.invoke(argv).toString()); 
  11. assertEquals(1, ((List) asListVar.invoke((Object)argv)).size()); 
  12. assertEquals("[three, thee, tee]", asListFix.invoke((Object)argv).toString()); 
  13. }

[中]生成一个固定算术方法句柄，该句柄在其他方面等同于当前方法句柄。
如果当前方法句柄不是#asVarargsCollector，则返回当前方法句柄。即使当前方法句柄不是asVarargsCollector的有效输入，也是如此。
否则，生成的固定arity方法句柄的类型和行为与当前方法句柄相同，只是#isvarargscollector将为false。fixed arity方法句柄可能是（也可能不是）asVarargsCollector的前一个参数。
下面是一个列表生成变量arity方法句柄的示例：

  1. MethodHandle asListVar = publicLookup()try { asListFix.invoke((Object)1); } 
  2. catch (Exception ex) { caught = ex; } 
  3. assert(caught instanceof ClassCastException); 
  4. assertEquals("[two, too]", asListVar.invoke("two", "too").toString()); 
  5. try { asListFix.invoke("two", "too"); } 
  6. catch (Exception ex) { caught = ex; } 
  7. assert(caught instanceof WrongMethodTypeException); 
  8. Object[] argv = { "three", "thee", "tee" }; 
  9. assertEquals("[three, thee, tee]", asListVar.invoke(argv).toString()); 
  10. assertEquals("[three, thee, tee]", asListFix.invoke(argv).toString()); 
  11. assertEquals(1, ((List) asListVar.invoke((Object)argv)).size()); 
  12. assertEquals("[three, thee, tee]", asListFix.invoke((Object)argv).toString()); 
  13. }

代码示例

代码示例来源：origin: eclipse/golo-lang

  1. public FunctionReference asFixedArity() {
  2.  return new FunctionReference(handle.asFixedArity(), this.parameterNames);
  3. }

代码示例来源：origin: beanshell/beanshell

  1. /** Appends varargs collector as appropriate to the MethodHandles lookup.
  2.  * The return pushes the cascade chaining result to the parent.
  3.  * {@inheritDoc} */
  4. @Override
  5. protected MethodHandle lookup(MethodHandle m) {
  6.   if (isVarArgs() && null != m)
  7.     return m.asFixedArity().asVarargsCollector(getVarArgsType());
  8.   return m;
  9. }

代码示例来源：origin: eclipse/golo-lang

  1. public MethodHandle coerce(MethodHandle target) {
  2.  if (target.isVarargsCollector() && isLastArgumentAnArray()) {
  3.   return target.asFixedArity().asType(type);
  4.  }
  5.  return target.asType(type);
  6. }

代码示例来源：origin: org.dynalang/dynalink

  1. OverloadedMethod(List<MethodHandle> methodHandles, OverloadedDynamicMethod parent, MethodType callSiteType,
  2.     LinkerServices linkerServices) {
  3.   this.parent = parent;
  4.   this.callSiteType = callSiteType;
  5.   this.linkerServices = linkerServices;
  6.   fixArgMethods = new ArrayList<>(methodHandles.size());
  7.   varArgMethods = new ArrayList<>(methodHandles.size());
  8.   final int argNum = callSiteType.parameterCount();
  9.   for(MethodHandle mh: methodHandles) {
  10.     if(mh.isVarargsCollector()) {
  11.       final MethodHandle asFixed = mh.asFixedArity();
  12.       if(argNum == asFixed.type().parameterCount()) {
  13.         fixArgMethods.add(asFixed);
  14.       }
  15.       varArgMethods.add(mh);
  16.     } else {
  17.       fixArgMethods.add(mh);
  18.     }
  19.   }
  20.   fixArgMethods.trimToSize();
  21.   varArgMethods.trimToSize();
  22.   final MethodHandle bound = SELECT_METHOD.bindTo(this);
  23.   final MethodHandle collecting = SingleDynamicMethod.collectArguments(bound, argNum).asType(
  24.       callSiteType.changeReturnType(MethodHandle.class));
  25.   invoker = MethodHandles.foldArguments(MethodHandles.exactInvoker(callSiteType), collecting);
  26. }

代码示例来源：origin: szegedi/dynalink

  1. OverloadedMethod(final List<MethodHandle> methodHandles, final OverloadedDynamicMethod parent, final MethodType callSiteType,
  2.     final LinkerServices linkerServices) {
  3.   this.parent = parent;
  4.   final Class<?> commonRetType = getCommonReturnType(methodHandles);
  5.   this.callSiteType = callSiteType.changeReturnType(commonRetType);
  6.   this.linkerServices = linkerServices;
  7.   fixArgMethods = new ArrayList<>(methodHandles.size());
  8.   varArgMethods = new ArrayList<>(methodHandles.size());
  9.   final int argNum = callSiteType.parameterCount();
  10.   for(MethodHandle mh: methodHandles) {
  11.     if(mh.isVarargsCollector()) {
  12.       final MethodHandle asFixed = mh.asFixedArity();
  13.       if(argNum == asFixed.type().parameterCount()) {
  14.         fixArgMethods.add(asFixed);
  15.       }
  16.       varArgMethods.add(mh);
  17.     } else {
  18.       fixArgMethods.add(mh);
  19.     }
  20.   }
  21.   fixArgMethods.trimToSize();
  22.   varArgMethods.trimToSize();
  23.   final MethodHandle bound = SELECT_METHOD.bindTo(this);
  24.   final MethodHandle collecting = SingleDynamicMethod.collectArguments(bound, argNum).asType(
  25.       callSiteType.changeReturnType(MethodHandle.class));
  26.   invoker = linkerServices.asTypeLosslessReturn(MethodHandles.foldArguments(
  27.       MethodHandles.exactInvoker(this.callSiteType), collecting), callSiteType);
  28. }

代码示例来源：origin: anba/es6draft

  1. handle = handle.asFixedArity();

代码示例来源：origin: baratine/baratine

  1. type = type.changeReturnType(void.class);
  2. mh = mh.asFixedArity();
  3. mh = mh.asType(type);

代码示例来源：origin: eclipse/golo-lang

  1. /**
  2.  * Spread arguments over this function parameters.
  3.  *
  4.  * @param arguments arguments as an array.
  5.  * @return a return value.
  6.  * @throws Throwable ...because an exception can be thrown.
  7.  */
  8. public Object spread(Object... arguments) throws Throwable {
  9.  int arity = arity();
  10.  if (this.handle.isVarargsCollector() && (arity > 0) && (arguments[arity - 1] instanceof Object[])) {
  11.   return this.handle
  12.     .asFixedArity()
  13.     .asSpreader(Object[].class, arguments.length)
  14.     .invoke(arguments);
  15.  }
  16.  return this.handle
  17.    .asSpreader(Object[].class, arguments.length)
  18.    .invoke(arguments);
  19. }

代码示例来源：origin: eclipse/golo-lang

  1. handle = handle.asFixedArity().asType(type);
  2.  } else {
  3.   handle = handle.asType(type);
  4. types = constructor.getParameterTypes();
  5. if (constructor.isVarArgs() && TypeMatching.isLastArgumentAnArray(types.length, args)) {
  6.  handle = caller.unreflectConstructor(constructor).asFixedArity().asType(type);
  7. } else {
  8.  handle = caller.unreflectConstructor(constructor).asType(type);

代码示例来源：origin: org.dynalang/dynalink

  1. final int paramsLen = methodType.parameterCount();
  2. final boolean varArgs = target.isVarargsCollector();
  3. final MethodHandle fixTarget = varArgs ? target.asFixedArity() : target;
  4. final int fixParamsLen = varArgs ? paramsLen - 1 : paramsLen;
  5. final int argsLen = callSiteType.parameterCount();

代码示例来源：origin: szegedi/dynalink

  1. final int paramsLen = methodType.parameterCount();
  2. final boolean varArgs = target.isVarargsCollector();
  3. final MethodHandle fixTarget = varArgs ? filteredTarget.asFixedArity() : filteredTarget;
  4. final int fixParamsLen = varArgs ? paramsLen - 1 : paramsLen;
  5. final int argsLen = callSiteType.parameterCount();

代码示例来源：origin: eclipse/golo-lang

  1. invoker = invoker.asFixedArity().asType(callSite.type());
  2. } else {
  3.  invoker = invoker.asCollector(

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