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org.codehaus.groovy.runtime.CurriedClosure Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.codehaus.groovy.runtime;
import groovy.lang.Closure;
/**
* A wrapper for Closure to support currying.
* Normally used only internally through the curry(), rcurry() or
* ncurry() methods on Closure.
* Typical usages:
*
* // normal usage
* def unitAdder = { first, second, unit -> "${first + second} $unit" }
* assert unitAdder(10, 15, "minutes") == "25 minutes"
* assert unitAdder.curry(60)(15, "minutes") == "75 minutes"
* def minuteAdder = unitAdder.rcurry("minutes")
* assert minuteAdder(15, 60) == "75 minutes"
*
* // explicit creation
* import org.codehaus.groovy.runtime.CurriedClosure
* assert new CurriedClosure(unitAdder, 45)(15, "minutes") == "60 minutes"
* assert new CurriedClosure(unitAdder, "six", "ty")("minutes") == "sixty minutes"
*
*
* Notes:
*
* Caters for Groovy's lazy (rcurry) and eager (ncurry) calculation of argument position
*
*/
public final class CurriedClosure extends Closure {
private static final long serialVersionUID = -1018388175778192754L;
private final Object[] curriedParams;
private final int minParamsExpected;
private int index;
private Class varargType = null;
/**
* Creates the curried closure.
*
* @param index the position where the parameters should be injected (-ve for lazy)
* @param uncurriedClosure the closure to be called after the curried parameters are injected
* @param arguments the supplied parameters
*/
public CurriedClosure(int index, Closure uncurriedClosure, Object... arguments) {
super(uncurriedClosure.clone());
curriedParams = arguments;
this.index = index;
final int origMaxLen = uncurriedClosure.getMaximumNumberOfParameters();
maximumNumberOfParameters = origMaxLen - arguments.length;
Class[] classes = uncurriedClosure.getParameterTypes();
Class lastType = classes.length == 0 ? null : classes[classes.length-1];
if (lastType != null && lastType.isArray()) {
varargType = lastType;
}
if (!isVararg()) {
// perform some early param checking for non-vararg case
if (index < 0) {
// normalise
this.index += origMaxLen;
minParamsExpected = 0;
} else {
minParamsExpected = index + arguments.length;
}
if (maximumNumberOfParameters < 0) {
throw new IllegalArgumentException("Can't curry " + arguments.length + " arguments for a closure with " + origMaxLen + " parameters.");
}
if (index < 0) {
if (index < -origMaxLen || index > -arguments.length)
throw new IllegalArgumentException("To curry " + arguments.length + " argument(s) expect index range " +
(-origMaxLen) + ".." + (-arguments.length) + " but found " + index);
} else if (index > maximumNumberOfParameters) {
throw new IllegalArgumentException("To curry " + arguments.length + " argument(s) expect index range 0.." +
maximumNumberOfParameters + " but found " + index);
}
} else {
minParamsExpected = 0;
}
}
public CurriedClosure(Closure uncurriedClosure, Object... arguments) {
this(0, uncurriedClosure, arguments);
}
public Object[] getUncurriedArguments(Object... arguments) {
if (isVararg()) {
int normalizedIndex = index < 0 ? index + arguments.length + curriedParams.length : index;
if (normalizedIndex < 0 || normalizedIndex > arguments.length) {
throw new IllegalArgumentException("When currying expected index range between " +
(-arguments.length - curriedParams.length) + ".." + (arguments.length + curriedParams.length) + " but found " + index);
}
return createNewCurriedParams(normalizedIndex, arguments);
}
if (curriedParams.length + arguments.length < minParamsExpected) {
throw new IllegalArgumentException("When currying expected at least " + index + " argument(s) to be supplied before known curried arguments but found " + arguments.length);
}
int newIndex = Math.min(index, curriedParams.length + arguments.length - 1);
// rcurried arguments are done lazily to allow normal method selection between overloaded alternatives
newIndex = Math.min(newIndex, arguments.length);
return createNewCurriedParams(newIndex, arguments);
}
private Object[] createNewCurriedParams(int normalizedIndex, Object[] arguments) {
Object[] newCurriedParams = new Object[curriedParams.length + arguments.length];
System.arraycopy(arguments, 0, newCurriedParams, 0, normalizedIndex);
System.arraycopy(curriedParams, 0, newCurriedParams, normalizedIndex, curriedParams.length);
if (arguments.length - normalizedIndex > 0)
System.arraycopy(arguments, normalizedIndex, newCurriedParams, curriedParams.length + normalizedIndex, arguments.length - normalizedIndex);
return newCurriedParams;
}
public void setDelegate(Object delegate) {
((Closure) getOwner()).setDelegate(delegate);
}
public Object getDelegate() {
return ((Closure) getOwner()).getDelegate();
}
public void setResolveStrategy(int resolveStrategy) {
((Closure) getOwner()).setResolveStrategy(resolveStrategy);
}
public int getResolveStrategy() {
return ((Closure) getOwner()).getResolveStrategy();
}
@SuppressWarnings("unchecked")
public Object clone() {
Closure uncurriedClosure = (Closure) ((Closure) getOwner()).clone();
return new CurriedClosure(index, uncurriedClosure, curriedParams);
}
public Class[] getParameterTypes() {
Class[] oldParams = ((Closure) getOwner()).getParameterTypes();
int extraParams = 0;
int gobbledParams = curriedParams.length;
if (isVararg()) {
int numNonVarargs = oldParams.length - 1;
if (index < 0) {
int absIndex = -index;
// do -ve indexes based on actual args, so can't accurately calculate type here
// so work out minimal type params and vararg on end will allow for other possibilities
if (absIndex > numNonVarargs) gobbledParams = numNonVarargs;
int newNumNonVarargs = numNonVarargs - gobbledParams;
if (absIndex - curriedParams.length > newNumNonVarargs) extraParams = absIndex - curriedParams.length - newNumNonVarargs;
int keptParams = Math.max(numNonVarargs - absIndex, 0);
Class[] newParams = new Class[keptParams + newNumNonVarargs + extraParams + 1];
System.arraycopy(oldParams, 0, newParams, 0, keptParams);
for (int i = 0; i < newNumNonVarargs; i++) newParams[keptParams + i] = Object.class;
for (int i = 0; i < extraParams; i++) newParams[keptParams + newNumNonVarargs + i] = varargType.getComponentType();
newParams[newParams.length - 1] = varargType;
return newParams;
}
int leadingKept = Math.min(index, numNonVarargs);
int trailingKept = Math.max(numNonVarargs - leadingKept - curriedParams.length, 0);
if (index > leadingKept) extraParams = index - leadingKept;
Class[] newParams = new Class[leadingKept + trailingKept + extraParams + 1];
System.arraycopy(oldParams, 0, newParams, 0, leadingKept);
if (trailingKept > 0) System.arraycopy(oldParams, leadingKept + curriedParams.length, newParams, leadingKept, trailingKept);
for (int i = 0; i < extraParams; i++) newParams[leadingKept + trailingKept + i] = varargType.getComponentType();
newParams[newParams.length - 1] = varargType;
return newParams;
}
Class[] newParams = new Class[oldParams.length - gobbledParams + extraParams];
System.arraycopy(oldParams, 0, newParams, 0, index);
if (newParams.length - index > 0)
System.arraycopy(oldParams, curriedParams.length + index, newParams, index, newParams.length - index);
return newParams;
}
private boolean isVararg() {
return varargType != null;
}
}
