groovy.lang.ObjectRange Maven / Gradle / Ivy
Show all versions of groovy Show documentation
/*
* 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.DefaultGroovyMethods;
import org.codehaus.groovy.runtime.FormatHelper;
import org.codehaus.groovy.runtime.InvokerHelper;
import org.codehaus.groovy.runtime.IteratorClosureAdapter;
import org.codehaus.groovy.runtime.ScriptBytecodeAdapter;
import org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation;
import org.codehaus.groovy.runtime.typehandling.NumberMath;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.AbstractList;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
/**
* Represents an inclusive list of objects from a value to a value using
* comparators.
*
* Note: This class is similar to {@link IntRange}. If you make any changes to this
* class, you might consider making parallel changes to {@link IntRange}.
*/
public class ObjectRange 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 cached size, or -1 if not yet computed
*/
private int size = -1;
/**
* true if the range counts backwards from to to from.
*/
private final boolean reverse;
/**
* Creates a new {@link ObjectRange}. Creates a reversed range if
* from < to.
*
* @param from the first value in the range.
* @param to the last value in the range.
*/
public ObjectRange(Comparable from, Comparable to) {
this(from, to, null);
}
/**
* Creates a new {@link ObjectRange} assumes smaller <= larger, else behavior is undefined.
* Caution: Prefer the other constructor when in doubt.
*
* Optimized Constructor avoiding initial computation of comparison.
*/
public ObjectRange(Comparable smaller, Comparable larger, boolean reverse) {
this(smaller, larger, (Boolean) reverse);
}
/**
* Constructs a Range, computing reverse if not provided. When providing reverse,
* 'smaller' must not be larger than 'larger'.
*
* @param smaller start of the range, must no be larger than to when reverse != null
* @param larger end of the range, must be larger than from when reverse != null
* @param reverse direction of the range. If null, causes direction to be computed (can be expensive).
*/
private ObjectRange(Comparable smaller, Comparable larger, Boolean reverse) {
if (smaller == null) {
throw new IllegalArgumentException("Must specify a non-null value for the 'from' index in a Range");
}
if (larger == null) {
throw new IllegalArgumentException("Must specify a non-null value for the 'to' index in a Range");
}
if (reverse == null) {
final boolean computedReverse = areReversed(smaller, larger);
// ensure invariant from <= to
if (computedReverse) {
final Comparable temp = larger;
larger = smaller;
smaller = temp;
}
this.reverse = computedReverse;
} else {
this.reverse = reverse;
}
if (smaller instanceof Short) {
smaller = ((Short) smaller).intValue();
} else if (smaller instanceof Float) {
smaller = ((Float) smaller).doubleValue();
}
if (larger instanceof Short) {
larger = ((Short) larger).intValue();
} else if (larger instanceof Float) {
larger = ((Float) larger).doubleValue();
}
if (smaller instanceof Integer && larger instanceof Long) {
smaller = ((Integer) smaller).longValue();
} else if (larger instanceof Integer && smaller instanceof Long) {
larger = ((Integer) larger).longValue();
}
/*
areReversed() already does an implicit type compatibility check
based on DefaultTypeTransformation.compareToWithEqualityCheck() for mixed classes
but it is only invoked if reverse == null.
So Object Range has to perform those type checks for consistency even when not calling
compareToWithEqualityCheck(), and ObjectRange has
to use the normalized value used in a successful comparison in
compareToWithEqualityCheck(). Currently that means Chars and single-char Strings
are evaluated as the char's charValue (an integer) when compared to numbers.
So '7'..'9' should produce ['7', '8', '9'], whereas ['7'..9] and [7..'9'] should produce [55, 56, 57].
if classes match, or both numerical, no checks possible / necessary
*/
if (smaller.getClass() == larger.getClass() ||
(smaller instanceof Number && larger instanceof Number)) {
this.from = smaller;
this.to = larger;
} else {
// Convenience hack: try convert single-char strings to ints
final Comparable tempfrom = normaliseStringType(smaller);
final Comparable tempto = normaliseStringType(larger);
// if after normalizing both are numbers, assume intended range was numbers
if (tempfrom instanceof Number && tempto instanceof Number) {
this.from = tempfrom;
this.to = tempto;
} else {
// if convenience hack did not make classes match,
// throw exception when starting with known class, and thus "from" cannot be advanced over "to".
// Note if start is an unusual Object, it could have a next() method
// that yields a Number or String to close the range
final Comparable start = this.reverse ? larger : smaller;
if (start instanceof String || start instanceof Number) {
// starting with number will never reach a non-number, same for string
throw new IllegalArgumentException("Incompatible Argument classes for ObjectRange " + smaller.getClass() + ", " + larger.getClass());
}
// Since normalizing did not help, use original values at user's risk
this.from = smaller;
this.to = larger;
}
}
checkBoundaryCompatibility();
}
/**
* throws IllegalArgumentException if to and from are incompatible, meaning they e.g. (likely) produce infinite sequences.
* Called at construction time, subclasses may override cautiously (using only members to and from).
*/
protected void checkBoundaryCompatibility() {
if (from instanceof String && to instanceof String) {
// this test depends deeply on the String.next implementation
// 009.next is 00:, not 010
final String start = from.toString();
final String end = to.toString();
if (start.length() != end.length()) {
throw new IllegalArgumentException("Incompatible Strings for Range: different length");
}
final int length = start.length();
int i;
for (i = 0; i < length; i++) {
if (start.charAt(i) != end.charAt(i)) {
break;
}
}
// strings must be equal except for the last character
if (i < length - 1) {
throw new IllegalArgumentException("Incompatible Strings for Range: String#next() will not reach the expected value");
}
}
}
private static boolean areReversed(Comparable from, Comparable to) {
try {
return ScriptBytecodeAdapter.compareGreaterThan(from, to);
} catch (IllegalArgumentException iae) {
throw new IllegalArgumentException("Unable to create range due to incompatible types: " + from.getClass().getSimpleName() + ".." + to.getClass().getSimpleName() + " (possible missing brackets around range?)", iae);
}
}
@Override
public boolean equals(Object that) {
return (that instanceof ObjectRange) ? equals((ObjectRange) that) : super.equals(that);
}
/**
* Compares an {@link ObjectRange} to another {@link ObjectRange}.
*
* @param that the object to check equality with
* @return true if the ranges are equal
*/
public boolean equals(ObjectRange that) {
return that != null
&& reverse == that.reverse
&& DefaultTypeTransformation.compareEqual(from, that.from)
&& DefaultTypeTransformation.compareEqual(to, that.to);
}
@Override
public Comparable getFrom() {
return from;
}
@Override
public Comparable getTo() {
return to;
}
@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 StepIterator iter = new StepIterator(this, 1);
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) {
if (value instanceof Comparable) {
final int result = compareTo(from, (Comparable) value);
return result == 0 || result < 0 && compareTo(to, (Comparable) value) >= 0;
}
return contains(value);
}
protected int compareTo(Comparable first, Comparable second) {
return DefaultGroovyMethods.numberAwareCompareTo(first, second);
}
/**
* 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) {
int tempsize = 0;
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 toNum = new BigInteger(to.toString());
final BigInteger sizeNum = toNum.subtract(fromNum).add(new BigInteger("1"));
tempsize = sizeNum.intValue();
if (!BigInteger.valueOf(tempsize).equals(sizeNum)) {
tempsize = Integer.MAX_VALUE;
}
} else if (from instanceof Character && to instanceof Character) {
// let's fast calculate the size
final char fromNum = (Character) from;
final char toNum = (Character) to;
tempsize = toNum - fromNum + 1;
} 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 = NumberMath.toBigDecimal((Number) from);
final BigDecimal toNum = NumberMath.toBigDecimal((Number) to);
final BigInteger sizeNum = toNum.subtract(fromNum).add(BigDecimal.ONE).toBigInteger();
tempsize = sizeNum.intValue();
if (!BigInteger.valueOf(tempsize).equals(sizeNum)) {
tempsize = Integer.MAX_VALUE;
}
} else {
// let's brute-force calculate the size by iterating start to end
final Iterator iter = new StepIterator(this, 1);
while (iter.hasNext()) {
tempsize++;
// integer overflow
if (tempsize < 0) {
break;
}
iter.next();
}
}
// integer overflow
if (tempsize < 0) {
tempsize = Integer.MAX_VALUE;
}
size = tempsize;
}
return size;
}
@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, 1);
Comparable toValue = iter.next();
int i = 0;
for (; i < fromIndex; i++) {
if (!iter.hasNext()) {
throw new IndexOutOfBoundsException("Index: " + i + " is too big for range: " + this);
}
toValue = iter.next();
}
final Comparable fromValue = toValue;
for (; i < toIndex - 1; i++) {
if (!iter.hasNext()) {
throw new IndexOutOfBoundsException("Index: " + i + " is too big for range: " + this);
}
toValue = iter.next();
}
return new ObjectRange(fromValue, toValue, reverse);
}
@Override
public String toString() {
return reverse ? "" + to + ".." + from : "" + from + ".." + to;
}
@Override
public String inspect() {
final String toText = FormatHelper.inspect(to);
final String fromText = FormatHelper.inspect(from);
return reverse ? "" + toText + ".." + fromText : "" + fromText + ".." + toText;
}
/**
* Iterates over all values and returns true if one value matches.
*
* @see #containsWithinBounds(Object)
*/
@Override
public boolean contains(Object value) {
final Iterator iter = new StepIterator(this, 1);
if (value == null) {
return false;
}
while (iter.hasNext()) {
if (DefaultTypeTransformation.compareEqual(value, iter.next())) return true;
}
return false;
}
@Override
public void step(int step, Closure closure) {
if (step == 0 && compareTo(from, to) == 0) {
return; // from == to and step == 0, nothing to do, so return
}
final Iterator iter = new StepIterator(this, step);
while (iter.hasNext()) {
closure.call(iter.next());
}
}
/**
* {@inheritDoc}
*/
@Override
public Iterator iterator() {
// non thread-safe iterator
return new StepIterator(this, 1);
}
/**
* Non-thread-safe iterator which lazily produces the next element only on calls of hasNext() or next()
*/
private static final class StepIterator implements Iterator {
// actual step, can be +1 when desired step is -1 and direction is from high to low
private final int step;
private final ObjectRange range;
private int index = -1;
private Comparable value;
private boolean nextFetched = true;
private StepIterator(ObjectRange range, final int desiredStep) {
if (desiredStep == 0 && range.compareTo(range.getFrom(), range.getTo()) != 0) {
throw new GroovyRuntimeException("Infinite loop detected due to step size of 0");
}
this.range = range;
if (range.isReverse()) {
step = -desiredStep;
} else {
step = desiredStep;
}
if (step > 0) {
value = range.getFrom();
} else {
value = range.getTo();
}
}
@Override
public void remove() {
range.remove(index);
}
@Override
public Comparable next() {
// not thread safe
if (!hasNext()) {
throw new NoSuchElementException();
}
nextFetched = false;
index++;
return value;
}
@Override
public boolean hasNext() {
// not thread safe
if (!nextFetched) {
value = peek();
nextFetched = true;
}
return value != null;
}
private Comparable peek() {
if (step > 0) {
Comparable peekValue = value;
for (int i = 0; i < step; i++) {
peekValue = (Comparable) range.increment(peekValue);
// handle back to beginning due to modulo incrementing
if (range.compareTo(peekValue, range.from) <= 0) return null;
}
if (range.compareTo(peekValue, range.to) <= 0) {
return peekValue;
}
} else {
final int positiveStep = -step;
Comparable peekValue = value;
for (int i = 0; i < positiveStep; i++) {
peekValue = (Comparable) range.decrement(peekValue);
// handle back to beginning due to modulo decrementing
if (range.compareTo(peekValue, range.to) >= 0) return null;
}
if (range.compareTo(peekValue, range.from) >= 0) {
return peekValue;
}
}
return null;
}
}
@Override
public List step(int step) {
final IteratorClosureAdapter adapter = new IteratorClosureAdapter(this);
step(step, adapter);
return adapter.asList();
}
/**
* Increments by one
*
* @param value the value to increment
* @return the incremented value
*/
protected Object increment(Object value) {
return InvokerHelper.invokeMethod(value, "next", null);
}
/**
* Decrements by one
*
* @param value the value to decrement
* @return the decremented value
*/
protected Object decrement(Object value) {
return InvokerHelper.invokeMethod(value, "previous", null);
}
/**
* if operand is a Character or a String with one character, return that character's int value.
*/
private static Comparable normaliseStringType(final Comparable operand) {
if (operand instanceof Character) {
return (int) (Character) operand;
}
if (operand instanceof String) {
final String string = (String) operand;
if (string.length() == 1) {
return (int) string.charAt(0);
}
return string;
}
return operand;
}
}