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Groovy: A powerful, dynamic language for the JVM
/*
* 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 groovy.lang;
import org.codehaus.groovy.runtime.InvokerHelper;
import org.codehaus.groovy.runtime.IteratorClosureAdapter;
import org.codehaus.groovy.runtime.RangeInfo;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.AbstractList;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import static org.codehaus.groovy.runtime.ScriptBytecodeAdapter.compareEqual;
import static org.codehaus.groovy.runtime.ScriptBytecodeAdapter.compareGreaterThan;
import static org.codehaus.groovy.runtime.ScriptBytecodeAdapter.compareGreaterThanEqual;
import static org.codehaus.groovy.runtime.ScriptBytecodeAdapter.compareLessThan;
import static org.codehaus.groovy.runtime.ScriptBytecodeAdapter.compareLessThanEqual;
import static org.codehaus.groovy.runtime.ScriptBytecodeAdapter.compareNotEqual;
import static org.codehaus.groovy.runtime.ScriptBytecodeAdapter.compareTo;
import static org.codehaus.groovy.runtime.dgmimpl.NumberNumberMinus.minus;
import static org.codehaus.groovy.runtime.dgmimpl.NumberNumberMultiply.multiply;
import static org.codehaus.groovy.runtime.dgmimpl.NumberNumberPlus.plus;
/**
* Represents an immutable list of Numbers from a value to a value with a particular step size.
*
* In general, it isn't recommended using a NumberRange as a key to a map. The range
* 0..3 is deemed to be equal to 0.0..3.0 but they have different hashCode values,
* so storing a value using one of these ranges couldn't be retrieved using the other.
*
* @since 2.5.0
*/
public class NumberRange extends AbstractList implements Range {
/**
* The first value in the range.
*/
private final Comparable from;
/**
* The last value in the range.
*/
private final Comparable to;
/**
* The step size in the range.
*/
private final Number stepSize;
/**
* The cached size, or -1 if not yet computed
*/
private int size = -1;
/**
* The cached hashCode (once calculated)
*/
private Integer hashCodeCache = null;
/**
* true if the range counts backwards from to to from.
*/
private final boolean reverse;
/**
* true if the range includes the upper bound.
*/
private final boolean inclusive;
/**
* Creates an inclusive {@link NumberRange} with step size 1.
* Creates a reversed range if from < to.
*
* @param from the first value in the range
* @param to the last value in the range
*/
public
NumberRange(T from, U to) {
this(from, to, null, true);
}
/**
* Creates a new {@link NumberRange} with step size 1.
* Creates a reversed range if from < to.
*
* @param from start of the range
* @param to end of the range
* @param inclusive whether the range is inclusive
*/
public
NumberRange(T from, U to, boolean inclusive) {
this(from, to, null, inclusive);
}
/**
* Creates an inclusive {@link NumberRange}.
* Creates a reversed range if from < to.
*
* @param from start of the range
* @param to end of the range
* @param stepSize the gap between discrete elements in the range
*/
public >
NumberRange(T from, U to, V stepSize) {
this(from, to, stepSize, true);
}
/**
* Creates a {@link NumberRange}.
* Creates a reversed range if from < to.
*
* @param from start of the range
* @param to end of the range
* @param stepSize the gap between discrete elements in the range
* @param inclusive whether the range is inclusive
*/
public
NumberRange(T from, U to, V stepSize, boolean inclusive) {
if (from == null) {
throw new IllegalArgumentException("Must specify a non-null value for the 'from' index in a Range");
}
if (to == null) {
throw new IllegalArgumentException("Must specify a non-null value for the 'to' index in a Range");
}
reverse = areReversed(from, to);
Number tempFrom;
Number tempTo;
if (reverse) {
tempFrom = to;
tempTo = from;
} else {
tempFrom = from;
tempTo = to;
}
if (tempFrom instanceof Short) {
tempFrom = tempFrom.intValue();
} else if (tempFrom instanceof Float) {
tempFrom = tempFrom.doubleValue();
}
if (tempTo instanceof Short) {
tempTo = tempTo.intValue();
} else if (tempTo instanceof Float) {
tempTo = tempTo.doubleValue();
}
if (tempFrom instanceof Integer && tempTo instanceof Long) {
tempFrom = tempFrom.longValue();
} else if (tempTo instanceof Integer && tempFrom instanceof Long) {
tempTo = tempTo.longValue();
}
this.from = (Comparable) tempFrom;
this.to = (Comparable) tempTo;
this.stepSize = stepSize == null ? 1 : stepSize;
this.inclusive = inclusive;
}
/**
* A method for determining from and to information when using this IntRange to index an aggregate object of the specified size.
* Normally only used internally within Groovy but useful if adding range indexing support for your own aggregates.
*
* @param size the size of the aggregate being indexed
* @return the calculated range information (with 1 added to the to value, ready for providing to subList
*/
public RangeInfo subListBorders(int size) {
if (stepSize.intValue() != 1) {
throw new IllegalStateException("Step must be 1 when used by subList!");
}
return IntRange.subListBorders(((Number) from).intValue(), ((Number) to).intValue(), inclusive, size);
}
/**
* For a NumberRange with step size 1, creates a new NumberRange with the same
* from and to as this NumberRange
* but with a step size of stepSize.
*
* @param stepSize the desired step size
* @return a new NumberRange
*/
public NumberRange by(T stepSize) {
if (!Integer.valueOf(1).equals(this.stepSize)) {
throw new IllegalStateException("by only allowed on ranges with original stepSize = 1 but found " + this.stepSize);
}
return new NumberRange(comparableNumber(from), comparableNumber(to), stepSize, inclusive);
}
@SuppressWarnings("unchecked")
/* package private */ static T comparableNumber(Comparable c) {
return (T) c;
}
@SuppressWarnings("unchecked")
/* package private */ static T comparableNumber(Number n) {
return (T) n;
}
private static boolean areReversed(Number from, Number to) {
try {
return compareGreaterThan(from, to);
} catch (ClassCastException cce) {
throw new IllegalArgumentException("Unable to create range due to incompatible types: " + from.getClass().getSimpleName() + ".." + to.getClass().getSimpleName() + " (possible missing brackets around range?)", cce);
}
}
/**
* An object is deemed equal to this NumberRange if it represents a List of items and
* those items equal the list of discrete items represented by this NumberRange.
*
* @param that the object to be compared for equality with this NumberRange
* @return {@code true} if the specified object is equal to this NumberRange
* @see #fastEquals(NumberRange)
*/
@Override
public boolean equals(Object that) {
return super.equals(that);
}
/**
* A NumberRange's hashCode is based on hashCode values of the discrete items it represents.
*
* @return the hashCode value
*/
@Override
public int hashCode() {
if (hashCodeCache == null) {
hashCodeCache = super.hashCode();
}
return hashCodeCache;
}
/*
* NOTE: as per the class javadoc, this class doesn't obey the normal equals/hashCode contract.
* The following field and method could assist some scenarios which required a similar sort of contract
* (but between equals and the custom canonicalHashCode). Currently commented out since we haven't
* found a real need. We will likely remove this commented out code if no usage is identified soon.
*/
/*
* The cached canonical hashCode (once calculated)
*/
// private Integer canonicalHashCodeCache = null;
/*
* A NumberRange's canonicalHashCode is based on hashCode values of the discrete items it represents.
* When two NumberRange's are equal they will have the same canonicalHashCode value.
* Numerical values which Groovy deems equal have the same hashCode during this calculation.
* So currently (0..3).equals(0.0..3.0) yet they have different hashCode values. This breaks
* the normal equals/hashCode contract which is a weakness in Groovy's '==' operator. However
* the contract isn't broken between equals and canonicalHashCode.
*
* @return the hashCode value
*/
// public int canonicalHashCode() {
// if (canonicalHashCodeCache == null) {
// int hashCode = 1;
// for (Comparable e : this) {
// int value;
// if (e == null) {
// value = 0;
// } else {
// BigDecimal next = new BigDecimal(e.toString());
// if (next.compareTo(BigDecimal.ZERO) == 0) {
// // workaround on pre-Java8 for http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6480539
// value = BigDecimal.ZERO.hashCode();
// } else {
// value = next.stripTrailingZeros().hashCode();
// }
// }
// hashCode = 31 * hashCode + value;
// }
// canonicalHashCodeCache = hashCode;
// }
// return canonicalHashCodeCache;
// }
/**
* Compares a {@link NumberRange} to another {@link NumberRange} using only a strict comparison
* of the NumberRange properties. This won't return true for some ranges which represent the same
* discrete items, use equals instead for that but will be much faster for large lists.
*
* @param that the NumberRange to check equality with
* @return true if the ranges are equal
*/
public boolean fastEquals(NumberRange that) {
return that != null
&& reverse == that.reverse
&& inclusive == that.inclusive
&& compareEqual(from, that.from)
&& compareEqual(to, that.to)
&& compareEqual(stepSize, that.stepSize);
}
/*
* NOTE: as per the class javadoc, this class doesn't obey the normal equals/hashCode contract.
* The following field and method could assist some scenarios which required a similar sort of contract
* (but between fastEquals and the custom fastHashCode). Currently commented out since we haven't
* found a real need. We will likely remove this commented out code if no usage is identified soon.
*/
/*
* The cached fast hashCode (once calculated)
*/
// private Integer fastHashCodeCache = null;
/*
* A hashCode function that pairs with fastEquals, following the normal equals/hashCode contract.
*
* @return the calculated hash code
*/
// public int fastHashCode() {
// if (fastHashCodeCache == null) {
// int result = 17;
// result = result * 31 + (reverse ? 1 : 0);
// result = result * 31 + (inclusive ? 1 : 0);
// result = result * 31 + new BigDecimal(from.toString()).stripTrailingZeros().hashCode();
// result = result * 31 + new BigDecimal(to.toString()).stripTrailingZeros().hashCode();
// result = result * 31 + new BigDecimal(stepSize.toString()).stripTrailingZeros().hashCode();
// fastHashCodeCache = result;
// }
// return fastHashCodeCache;
// }
@Override
public Comparable getFrom() {
return from;
}
@Override
public Comparable getTo() {
return to;
}
public Comparable getStepSize() {
return (Comparable) stepSize;
}
@Override
public boolean isReverse() {
return reverse;
}
@Override
public Comparable get(int index) {
if (index < 0) {
throw new IndexOutOfBoundsException("Index: " + index + " should not be negative");
}
final Iterator iter = new StepIterator(this, stepSize);
Comparable value = iter.next();
for (int i = 0; i < index; i++) {
if (!iter.hasNext()) {
throw new IndexOutOfBoundsException("Index: " + index + " is too big for range: " + this);
}
value = iter.next();
}
return value;
}
/**
* Checks whether a value is between the from and to values of a Range
*
* @param value the value of interest
* @return true if the value is within the bounds
*/
@Override
public boolean containsWithinBounds(Object value) {
final int result = compareTo(from, value);
return result == 0 || result < 0 && compareTo(to, value) >= 0;
}
/**
* protection against calls from Groovy
*/
@SuppressWarnings("unused")
private void setSize(int size) {
throw new UnsupportedOperationException("size must not be changed");
}
@Override
public int size() {
if (size == -1) {
calcSize(from, to, stepSize);
}
return size;
}
void calcSize(Comparable from, Comparable to, Number stepSize) {
int tempsize = 0;
boolean shortcut = false;
if (isIntegral(stepSize)) {
if ((from instanceof Integer || from instanceof Long)
&& (to instanceof Integer || to instanceof Long)) {
// let's fast calculate the size
final BigInteger fromNum = new BigInteger(from.toString());
final BigInteger toTemp = new BigInteger(to.toString());
final BigInteger toNum = inclusive ? toTemp : toTemp.subtract(BigInteger.ONE);
final BigInteger sizeNum = new BigDecimal(toNum.subtract(fromNum)).divide(new BigDecimal(stepSize.longValue()), BigDecimal.ROUND_DOWN).toBigInteger().add(BigInteger.ONE);
tempsize = sizeNum.compareTo(BigInteger.valueOf(Integer.MAX_VALUE)) == -1 ? sizeNum.intValue() : Integer.MAX_VALUE;
shortcut = true;
} else if (((from instanceof BigDecimal || from instanceof BigInteger) && to instanceof Number) ||
((to instanceof BigDecimal || to instanceof BigInteger) && from instanceof Number)) {
// let's fast calculate the size
final BigDecimal fromNum = new BigDecimal(from.toString());
final BigDecimal toTemp = new BigDecimal(to.toString());
final BigDecimal toNum = inclusive ? toTemp : toTemp.subtract(new BigDecimal("1.0"));
final BigInteger sizeNum = toNum.subtract(fromNum).divide(new BigDecimal(stepSize.longValue()), BigDecimal.ROUND_DOWN).toBigInteger().add(BigInteger.ONE);
tempsize = sizeNum.compareTo(BigInteger.valueOf(Integer.MAX_VALUE)) == -1 ? sizeNum.intValue() : Integer.MAX_VALUE;
shortcut = true;
}
}
if (!shortcut) {
// let's brute-force calculate the size by iterating start to end
final Iterator iter = new StepIterator(this, stepSize);
while (iter.hasNext()) {
tempsize++;
// integer overflow
if (tempsize < 0) {
break;
}
iter.next();
}
// integer overflow
if (tempsize < 0) {
tempsize = Integer.MAX_VALUE;
}
}
size = tempsize;
}
private boolean isIntegral(Number stepSize) {
BigDecimal tempStepSize = new BigDecimal(stepSize.toString());
return tempStepSize.equals(new BigDecimal(tempStepSize.toBigInteger()));
}
@Override
public List subList(int fromIndex, int toIndex) {
if (fromIndex < 0) {
throw new IndexOutOfBoundsException("fromIndex = " + fromIndex);
}
if (fromIndex > toIndex) {
throw new IllegalArgumentException("fromIndex(" + fromIndex + ") > toIndex(" + toIndex + ")");
}
if (fromIndex == toIndex) {
return new EmptyRange(from);
}
// Performance detail:
// not using get(fromIndex), get(toIndex) in the following to avoid stepping over elements twice
final Iterator iter = new StepIterator(this, stepSize);
Comparable value = iter.next();
int i = 0;
for (; i < fromIndex; i++) {
if (!iter.hasNext()) {
throw new IndexOutOfBoundsException("Index: " + i + " is too big for range: " + this);
}
value = iter.next();
}
final Comparable fromValue = value;
for (; i < toIndex - 1; i++) {
if (!iter.hasNext()) {
throw new IndexOutOfBoundsException("Index: " + i + " is too big for range: " + this);
}
value = iter.next();
}
final Comparable toValue = value;
return new NumberRange(comparableNumber(fromValue), comparableNumber(toValue), comparableNumber(stepSize), true);
}
@Override
public String toString() {
return getToString(to.toString(), from.toString());
}
@Override
public String inspect() {
return getToString(InvokerHelper.inspect(to), InvokerHelper.inspect(from));
}
private String getToString(String toText, String fromText) {
String sep = inclusive ? ".." : "..<";
String base = reverse ? "" + toText + sep + fromText : "" + fromText + sep + toText;
return Integer.valueOf(1).equals(stepSize) ? base : base + ".by(" + stepSize + ")";
}
/**
* iterates over all values and returns true if one value matches.
* Also see containsWithinBounds.
*/
@Override
public boolean contains(Object value) {
if (value == null) {
return false;
}
final Iterator it = new StepIterator(this, stepSize);
while (it.hasNext()) {
if (compareEqual(value, it.next())) {
return true;
}
}
return false;
}
/**
* {@inheritDoc}
*/
@Override
public void step(int numSteps, Closure closure) {
if (numSteps == 0 && compareTo(from, to) == 0) {
return; // from == to and step == 0, nothing to do, so return
}
final StepIterator iter = new StepIterator(this, multiply(numSteps, stepSize));
while (iter.hasNext()) {
closure.call(iter.next());
}
}
/**
* {@inheritDoc}
*/
@Override
public Iterator iterator() {
return new StepIterator(this, stepSize);
}
/**
* convenience class to serve in other methods.
* It's not thread-safe, and lazily produces the next element only on calls of hasNext() or next()
*/
private class StepIterator implements Iterator {
private final NumberRange range;
private final Number step;
private final boolean isAscending;
private boolean isNextFetched = false;
private Comparable next = null;
StepIterator(NumberRange range, Number step) {
if (compareEqual(step, 0) && compareNotEqual(range.getFrom(), range.getTo())) {
throw new GroovyRuntimeException("Infinite loop detected due to step size of 0");
}
this.range = range;
if (compareLessThan(step, 0)) {
this.step = multiply(step, -1);
isAscending = range.isReverse();
} else {
this.step = step;
isAscending = !range.isReverse();
}
}
@Override
public boolean hasNext() {
fetchNextIfNeeded();
return (next != null) && (isAscending
? (range.inclusive ? compareLessThanEqual(next, range.getTo()) : compareLessThan(next, range.getTo()))
: (range.inclusive ? compareGreaterThanEqual(next, range.getFrom()) : compareGreaterThan(next, range.getFrom())));
}
@Override
public Comparable next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
fetchNextIfNeeded();
isNextFetched = false;
return next;
}
private void fetchNextIfNeeded() {
if (!isNextFetched) {
isNextFetched = true;
if (next == null) {
// make the first fetch lazy too
next = isAscending ? range.getFrom() : range.getTo();
} else {
next = isAscending ? increment(next, step) : decrement(next, step);
}
}
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
}
@Override
public List step(int numSteps) {
final IteratorClosureAdapter adapter = new IteratorClosureAdapter(this);
step(numSteps, adapter);
return adapter.asList();
}
/**
* Increments by given step
*
* @param value the value to increment
* @param step the amount to increment
* @return the incremented value
*/
@SuppressWarnings("unchecked")
private Comparable increment(Object value, Number step) {
return (Comparable) plus((Number) value, step);
}
/**
* Decrements by given step
*
* @param value the value to decrement
* @param step the amount to decrement
* @return the decremented value
*/
@SuppressWarnings("unchecked")
private Comparable decrement(Object value, Number step) {
return (Comparable) minus((Number) value, step);
}
}
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