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* Licensed to the Apache Software Foundation (ASF) under one
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* to you under the Apache License, Version 2.0 (the
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* 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
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* specific language governing permissions and limitations
* under the License.
*/
package groovy.lang;
import java.util.List;
/**
* A Range represents the list of discrete items between some starting (or from)
* value and working up towards some ending (or to) value.
* For a reverse range, the list is obtained by starting at the to value and
* working down towards the from value.
*
* The concept of working up and working down is dependent on the range implementation.
* In the general case, working up involves successive calls to the first item's next()
* method while working down involves calling the previous() method. Optimized
* numerical ranges may apply numeric addition or subtraction of some numerical step size.
*
* Particular range implementations may also support the notion of inclusivity
* and exclusivity with respect to the ending value in the range.
* E.g. {@code 1..3 == [1, 2, 3]}; but {@code 1..<3 == [1, 2]}.
*
* In general, the second boundary may not be contained in the range,
* and a..b may produce a different set of elements than (b..a).reversed().
* E.g. 1..2.5 == [1, 2]; but 2.5..1 == [2.5, 1.5].
*
* Implementations can be memory efficient by storing just the from and to boundary
* values rather than eagerly creating all discrete items in the conceptual list. The actual discrete items
* can be lazily calculated on an as needed basis (e.g. when calling methods from the java.util.List
* interface or the additional step methods in the Range interface).
*
* In addition to the methods related to a Range's "discrete items" abstraction, there is a method,
* containsWithinBounds which, for numerical ranges, allows checking within the continuous
* interval between the Range's boundary values.
*/
public interface Range extends List {
/**
* The lower value in the range.
*
* @return the lower value in the range.
*/
T getFrom();
/**
* The upper value in the range.
*
* @return the upper value in the range
*/
T getTo();
/**
* Indicates whether this is a reverse range which iterates backwards
* starting from the to value and ending on the from value
*
* @return true if this is a reverse range
*/
boolean isReverse();
/**
* Indicates whether an object is greater than or equal to the from
* value for the range and less than or equal to the to value.
*
* This may be true even for values not contained in the range.
*
* Example: from = 1.5, to = 3, next() increments by 1
* containsWithinBounds(2) == true
* contains(2) == false
*
* @param o the object to check against the boundaries of the range
* @return true if the object is between the from and to values
*/
boolean containsWithinBounds(Object o);
/**
* Steps through the range, calling a closure for each item.
*
* @param step the amount by which to step. If negative, steps through the range backwards.
* @param closure the {@link Closure} to call
*/
void step(int step, Closure closure);
/**
* Forms a list by stepping through the range by the indicated interval.
*
* @param step the amount by which to step. If negative, steps through the range backwards.
* @return the list formed by stepping through the range by the indicated interval.
*/
List step(int step);
/**
* @return the verbose {@link String} representation of this {@link Range} as would be typed into a console to create the {@link Range} instance
*/
String inspect();
}