Skip to content

Commit

Permalink
Avoid NoSuchElementException in MathPlume.modulusStrictLong
Browse files Browse the repository at this point in the history
  • Loading branch information
@jyoo980
jyoo980 authored Jan 26, 2024
1 parent f320f72 commit eac98f2
Show file tree
Hide file tree
Showing 2 changed files with 143 additions and 1 deletion.
5 changes: 4 additions & 1 deletion src/main/java/org/plumelib/util/MathPlume.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1229,6 +1229,9 @@ public static double gcdDifferences(double[] a) {
long lastNonstrict = 0; // arbitrary initial value
if (nonstrictEnds) {
firstNonstrict = itor.next().longValue();
if (!itor.hasNext()) {
return null;
}
}

long prev = itor.next().longValue();
Expand All @@ -1237,7 +1240,7 @@ public static double gcdDifferences(double[] a) {
}
long next = itor.next().longValue();
long modulus = next - prev;
if (modulus == 1) {
if (modulus == 1 || modulus == 0) {
return null;
}
int count = 2;
Expand Down
139 changes: 139 additions & 0 deletions src/test/java/org/plumelib/util/MathPlumeTest.java
View file
Original file line number Diff line number Diff line change
@@ -1,12 +1,15 @@
package org.plumelib.util;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNull;
import static org.junit.jupiter.api.Assertions.assertTrue;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import org.checkerframework.checker.nullness.qual.Nullable;
import org.checkerframework.common.value.qual.ArrayLen;
import org.junit.jupiter.api.Test;

public final class MathPlumeTest {
Expand All @@ -25,6 +28,16 @@ private static void assertArraysEquals(int @Nullable [] a1, int @Nullable [] a2)
// "Arrays differ: " + ArraysPlume.toString(a1) + ", " + ArraysPlume.toString(a2));
}

private static void assertArraysEquals(long @Nullable [] a1, long @Nullable [] a2) {
boolean result = Arrays.equals(a1, a2);
if (!result) {
System.out.println("Arrays differ: " + Arrays.toString(a1) + ", " + Arrays.toString(a2));
}
assertTrue(result);
// assert(Arrays.equals(a1, a2),
// "Arrays differ: " + ArraysPlume.toString(a1) + ", " + ArraysPlume.toString(a2));
}

// private static void assertArraysEquals(double[] a1, double[] a2) {
// boolean result = Arrays.equals(a1, a2);
// if (!result) {
Expand Down Expand Up @@ -251,6 +264,78 @@ void checkIterator(int[] nums, int @Nullable [] goalRm) {
}
}

static class TestModulusLong {
void check(long[] nums, long @Nullable [] goalRm) {
long[] rm = MathPlume.modulusLong(Arrays.stream(nums).iterator());
if (!Arrays.equals(rm, goalRm)) {
throw new Error(
"Expected (r,m)=" + Arrays.toString(goalRm) + ", saw (r,m)=" + Arrays.toString(rm));
}
if (rm == null) {
return;
}
long goalR = rm[0];
long m = rm[1];
for (int i = 0; i < nums.length; i++) {
long r = nums[i] % m;
if (r < 0) {
r += m;
}
if (r != goalR) {
throw new Error("Expected " + nums[i] + " % " + m + " = " + goalR + ", got " + r);
}
}
}

void check(Iterator<Long> itor, long @Nullable [] goalRm) {
// There would be no point to this: it's testing
// longIteratorArray, not the iterator version!
// return check(longIteratorArray(itor), goalRm);
assertArraysEquals(MathPlume.modulusLong(itor), goalRm);
}

void checkIterator(long[] nums, long @Nullable [] goalRm) {
check(Arrays.stream(nums).iterator(), goalRm);
}

void checkStrict(long[] nums, long @Nullable @ArrayLen(2) [] goalRm) {
long[] rm = MathPlume.modulusStrictLong(Arrays.stream(nums).iterator(), false);
if (goalRm == null) {
assertNull(rm);
} else {
assertArraysEquals(goalRm, rm);
long modulus = goalRm[1];
if (nums.length == 0) {
throw new Error("this can't happen, because goalRm is not null");
}
long first = nums[0];
for (int i = 0; i < nums.length; i++) {
assertEquals(nums[i], first + i * modulus);
}
}
}

void checkStrictNonStrictEnds(long[] nums, long @Nullable @ArrayLen(2) [] goalRm) {
long[] rm = MathPlume.modulusStrictLong(Arrays.stream(nums).iterator(), true);
if (goalRm == null) {
assertNull(rm);
} else {
assertArraysEquals(goalRm, rm);
long remainder = goalRm[0];
long modulus = goalRm[1];
if (nums.length < 3) {
throw new Error("this can't happen, because goalRm is not null");
}
assertEquals(remainder, nums[0] % modulus);
assertEquals(remainder, nums[nums.length - 1] % modulus);
long first = nums[1];
for (int i = 1; i < nums.length - 1; i++) {
assertEquals(nums[i], first + (i - 1) * modulus);
}
}
}
}

static class TestNonModulus {
void checkStrict(int[] nums, int @Nullable [] goalRm) {
check(nums, goalRm, true);
Expand Down Expand Up @@ -317,6 +402,60 @@ public void test_modulus() {
testModulus.checkIterator(new int[] {2383, 4015, -81, 463, -689}, new int[] {15, 32});
testModulus.checkIterator(new int[] {5, 5, 5, 5, 5}, null);

TestModulusLong testModulusLong = new TestModulusLong();

testModulusLong.check(new long[] {3, 7, 47, 51}, new long[] {3, 4});
testModulusLong.check(new long[] {3, 11, 43, 51}, new long[] {3, 8});
testModulusLong.check(new long[] {3, 11, 47, 55}, new long[] {3, 4});
testModulusLong.check(new long[] {2383, 4015, -81, 463, -689}, new long[] {15, 32});
testModulusLong.check(new long[] {}, null);
testModulusLong.check(new long[] {1}, null);
testModulusLong.check(new long[] {3, 7}, null);
testModulusLong.check(new long[] {2, 3, 5, 7}, null);
testModulusLong.check(new long[] {2, 19, 101}, null);
testModulusLong.check(new long[] {5, 5, 5, 5, 5}, null);

testModulusLong.checkStrict(new long[] {3, 7, 11, 15}, new long[] {3, 4});
testModulusLong.checkStrict(new long[] {3, 11, 19, 27}, new long[] {3, 8});
testModulusLong.checkStrict(new long[] {27, 3, 11, 19, 27, -5}, null);
testModulusLong.checkStrict(new long[] {3, 11}, null);
testModulusLong.checkStrict(new long[] {3}, null);
testModulusLong.checkStrict(new long[] {2383, 4015, -81, 463, -689}, null);
testModulusLong.checkStrict(new long[] {}, null);
testModulusLong.checkStrict(new long[] {1}, null);
testModulusLong.checkStrict(new long[] {3, 7}, null);
testModulusLong.checkStrict(new long[] {2, 3, 5, 7}, null);
testModulusLong.checkStrict(new long[] {2, 19, 101}, null);
testModulusLong.checkStrict(new long[] {5, 5, 5, 5, 5}, null);

testModulusLong.checkStrictNonStrictEnds(new long[] {3, 7, 11, 15, 19}, new long[] {3, 4});
testModulusLong.checkStrictNonStrictEnds(new long[] {3, 11, 19, 27, 35}, new long[] {3, 8});
// TODO testModulusLong.checkStrictNonStrictEnds(new long[] {3, 7, 11, 15}, new long[] {3, 4});
// TODO testModulusLong.checkStrictNonStrictEnds(new long[] {3, 11, 19, 27}, new long[] {3, 8});
testModulusLong.checkStrictNonStrictEnds(
new long[] {27, 3, 11, 19, 27, 203}, new long[] {3, 8});
// TODO testModulusLong.checkStrictNonStrictEnds(new long[] {27, 3, 11, 19, 27, -5}, new long[]
// {3, 8});
// TODO testModulusLong.checkStrictNonStrictEnds(new long[] {11, 7, 3}, new long[] {3, 4});
// TODO testModulusLong.checkStrictNonStrictEnds(new long[] {15, 7, 3}, new long[] {3, 4});
// TODO testModulusLong.checkStrictNonStrictEnds(new long[] {3, 11}, new long[] {3, 8});
testModulusLong.checkStrictNonStrictEnds(new long[] {3}, null);
testModulusLong.checkStrictNonStrictEnds(new long[] {2383, 4015, -81, 463, -689}, null);
testModulusLong.checkStrictNonStrictEnds(new long[] {}, null);
testModulusLong.checkStrictNonStrictEnds(new long[] {1}, null);
testModulusLong.checkStrictNonStrictEnds(new long[] {3, 7}, null);
testModulusLong.checkStrictNonStrictEnds(new long[] {2, 3, 5, 7}, null);
testModulusLong.checkStrictNonStrictEnds(new long[] {2, 19, 101}, null);
testModulusLong.checkStrictNonStrictEnds(new long[] {5, 5, 5, 5, 5}, null);

testModulusLong.checkIterator(new long[] {}, null);
testModulusLong.checkIterator(new long[] {1}, null);
testModulusLong.checkIterator(new long[] {3, 7, 47, 51}, new long[] {3, 4});
testModulusLong.checkIterator(new long[] {3, 11, 43, 51}, new long[] {3, 8});
testModulusLong.checkIterator(new long[] {3, 11, 47, 55}, new long[] {3, 4});
testModulusLong.checkIterator(new long[] {2383, 4015, -81, 463, -689}, new long[] {15, 32});
testModulusLong.checkIterator(new long[] {5, 5, 5, 5, 5}, null);

// int[] nonmodulusStrict(int[] nums)
// int[] nonmodulusNonstrict(int[] nums)
// int[] nonmodulusStrict(Iterator nums)
Expand Down

0 comments on commit eac98f2

Please sign in to comment.