org.antlr.v4.runtime.misc.Interval Maven / Gradle / Ivy
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/*
* [The "BSD license"]
* Copyright (c) 2012 Terence Parr
* Copyright (c) 2012 Sam Harwell
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.antlr.v4.runtime.misc;
/** An immutable inclusive interval a..b */
public class Interval {
public static final int INTERVAL_POOL_MAX_VALUE = 1000;
public static final Interval INVALID = new Interval(-1,-2);
static Interval[] cache = new Interval[INTERVAL_POOL_MAX_VALUE+1];
public int a;
public int b;
public static int creates = 0;
public static int misses = 0;
public static int hits = 0;
public static int outOfRange = 0;
public Interval(int a, int b) { this.a=a; this.b=b; }
/** Interval objects are used readonly so share all with the
* same single value a==b up to some max size. Use an array as a perfect hash.
* Return shared object for 0..INTERVAL_POOL_MAX_VALUE or a new
* Interval object with a..a in it. On Java.g4, 218623 IntervalSets
* have a..a (set with 1 element).
*/
public static Interval of(int a, int b) {
// cache just a..a
if ( a!=b || a<0 || a>INTERVAL_POOL_MAX_VALUE ) {
return new Interval(a,b);
}
if ( cache[a]==null ) {
cache[a] = new Interval(a,a);
}
return cache[a];
}
/** return number of elements between a and b inclusively. x..x is length 1.
* if b < a, then length is 0. 9..10 has length 2.
*/
public int length() {
if ( b=other.a;
}
/** Does this.a start after other.b? May or may not be disjoint */
public boolean startsAfter(Interval other) { return this.a>other.a; }
/** Does this start completely after other? Disjoint */
public boolean startsAfterDisjoint(Interval other) {
return this.a>other.b;
}
/** Does this start after other? NonDisjoint */
public boolean startsAfterNonDisjoint(Interval other) {
return this.a>other.a && this.a<=other.b; // this.b>=other.b implied
}
/** Are both ranges disjoint? I.e., no overlap? */
public boolean disjoint(Interval other) {
return startsBeforeDisjoint(other) || startsAfterDisjoint(other);
}
/** Are two intervals adjacent such as 0..41 and 42..42? */
public boolean adjacent(Interval other) {
return this.a == other.b+1 || this.b == other.a-1;
}
public boolean properlyContains(Interval other) {
return other.a >= this.a && other.b <= this.b;
}
/** Return the interval computed from combining this and other */
public Interval union(Interval other) {
return Interval.of(Math.min(a, other.a), Math.max(b, other.b));
}
/** Return the interval in common between this and o */
public Interval intersection(Interval other) {
return Interval.of(Math.max(a, other.a), Math.min(b, other.b));
}
/** Return the interval with elements from this not in other;
* other must not be totally enclosed (properly contained)
* within this, which would result in two disjoint intervals
* instead of the single one returned by this method.
*/
public Interval differenceNotProperlyContained(Interval other) {
Interval diff = null;
// other.a to left of this.a (or same)
if ( other.startsBeforeNonDisjoint(this) ) {
diff = Interval.of(Math.max(this.a, other.b + 1),
this.b);
}
// other.a to right of this.a
else if ( other.startsAfterNonDisjoint(this) ) {
diff = Interval.of(this.a, other.a - 1);
}
return diff;
}
@Override
public String toString() {
return a+".."+b;
}
}