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Extend StreamRules Refaster rule collection #593

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merged 6 commits into from
Apr 26, 2023
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Merged

Extend StreamRules Refaster rule collection #593

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3fe9b10
578-refaster-rule-that-replaces-redundant-streamcollect-calls
Apr 23, 2023
f362d89
578 Fix issue where output test (parser?) expects the same imports fr…
Apr 23, 2023
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Add new SonarCloud suppressions
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177 changes: 172 additions & 5 deletions error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/StreamRules.java
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,20 @@
import static java.util.Comparator.naturalOrder;
import static java.util.Comparator.reverseOrder;
import static java.util.function.Predicate.not;
import static java.util.stream.Collectors.counting;
import static java.util.stream.Collectors.filtering;
import static java.util.stream.Collectors.flatMapping;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.mapping;
import static java.util.stream.Collectors.maxBy;
import static java.util.stream.Collectors.minBy;
import static java.util.stream.Collectors.reducing;
import static java.util.stream.Collectors.summarizingDouble;
import static java.util.stream.Collectors.summarizingInt;
import static java.util.stream.Collectors.summarizingLong;
import static java.util.stream.Collectors.summingDouble;
import static java.util.stream.Collectors.summingInt;
import static java.util.stream.Collectors.summingLong;

import com.google.common.collect.Streams;
import com.google.errorprone.refaster.Refaster;
Expand All @@ -16,8 +29,12 @@
import com.google.errorprone.refaster.annotation.UseImportPolicy;
import java.util.Arrays;
import java.util.Comparator;
import java.util.DoubleSummaryStatistics;
import java.util.IntSummaryStatistics;
import java.util.LongSummaryStatistics;
import java.util.Objects;
import java.util.Optional;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.ToDoubleFunction;
Expand Down Expand Up @@ -263,9 +280,12 @@ boolean after(Stream<T> stream) {

static final class StreamMin<T> {
@BeforeTemplate
@SuppressWarnings("java:S4266" /* This violation will be rewritten. */)
Optional<T> before(Stream<T> stream, Comparator<? super T> comparator) {
return Refaster.anyOf(
stream.max(comparator.reversed()), stream.sorted(comparator).findFirst());
stream.max(comparator.reversed()),
stream.sorted(comparator).findFirst(),
stream.collect(minBy(comparator)));
}

@AfterTemplate
Expand All @@ -289,9 +309,12 @@ Optional<T> after(Stream<T> stream) {

static final class StreamMax<T> {
@BeforeTemplate
@SuppressWarnings("java:S4266" /* This violation will be rewritten. */)
Optional<T> before(Stream<T> stream, Comparator<? super T> comparator) {
return Refaster.anyOf(
stream.min(comparator.reversed()), Streams.findLast(stream.sorted(comparator)));
stream.min(comparator.reversed()),
Streams.findLast(stream.sorted(comparator)),
stream.collect(maxBy(comparator)));
}

@AfterTemplate
Expand Down Expand Up @@ -389,7 +412,13 @@ boolean after(Stream<T> stream) {

static final class StreamMapToIntSum<T> {
@BeforeTemplate
int before(
@SuppressWarnings("java:S4266" /* This violation will be rewritten. */)
long before(Stream<T> stream, ToIntFunction<T> mapper) {
return stream.collect(summingInt(mapper));
}

@BeforeTemplate
int before2(
Stream<T> stream,
@Matches(IsLambdaExpressionOrMethodReference.class) Function<? super T, Integer> mapper) {
return stream.map(mapper).reduce(0, Integer::sum);
Expand All @@ -403,7 +432,13 @@ int after(Stream<T> stream, ToIntFunction<T> mapper) {

static final class StreamMapToDoubleSum<T> {
@BeforeTemplate
double before(
@SuppressWarnings("java:S4266" /* This violation will be rewritten. */)
double before(Stream<T> stream, ToDoubleFunction<T> mapper) {
return stream.collect(summingDouble(mapper));
}

@BeforeTemplate
double before2(
Stream<T> stream,
@Matches(IsLambdaExpressionOrMethodReference.class) Function<? super T, Double> mapper) {
return stream.map(mapper).reduce(0.0, Double::sum);
Expand All @@ -417,7 +452,13 @@ static final class StreamMapToDoubleSum<T> {

static final class StreamMapToLongSum<T> {
@BeforeTemplate
long before(
@SuppressWarnings("java:S4266" /* This violation will be rewritten. */)
long before(Stream<T> stream, ToLongFunction<T> mapper) {
return stream.collect(summingLong(mapper));
}

@BeforeTemplate
long before2(
Stream<T> stream,
@Matches(IsLambdaExpressionOrMethodReference.class) Function<? super T, Long> mapper) {
return stream.map(mapper).reduce(0L, Long::sum);
Expand All @@ -428,4 +469,130 @@ long after(Stream<T> stream, ToLongFunction<T> mapper) {
return stream.mapToLong(mapper).sum();
}
}

static final class StreamMapToIntSummaryStatistics<T> {
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I'd suspect *SummaryStatistics rules to be at the end as they are not directly on Stream 🤔.

So the ordering is not lexicographical but also not based on the order of Stream itself 🤔. filter, map and flatMap things are first in that class.

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If you want to reorder things based on a formula that we can eventually automate/auto-enforce: go for it 😄

@BeforeTemplate
IntSummaryStatistics before(Stream<T> stream, ToIntFunction<T> mapper) {
return stream.collect(summarizingInt(mapper));
}

@AfterTemplate
IntSummaryStatistics after(Stream<T> stream, ToIntFunction<T> mapper) {
return stream.mapToInt(mapper).summaryStatistics();
}
}

static final class StreamMapToDoubleSummaryStatistics<T> {
@BeforeTemplate
DoubleSummaryStatistics before(Stream<T> stream, ToDoubleFunction<T> mapper) {
return stream.collect(summarizingDouble(mapper));
}

@AfterTemplate
DoubleSummaryStatistics after(Stream<T> stream, ToDoubleFunction<T> mapper) {
return stream.mapToDouble(mapper).summaryStatistics();
}
}

static final class StreamMapToLongSummaryStatistics<T> {
@BeforeTemplate
LongSummaryStatistics before(Stream<T> stream, ToLongFunction<T> mapper) {
return stream.collect(summarizingLong(mapper));
}

@AfterTemplate
LongSummaryStatistics after(Stream<T> stream, ToLongFunction<T> mapper) {
return stream.mapToLong(mapper).summaryStatistics();
}
}

static final class StreamCount<T> {
@BeforeTemplate
@SuppressWarnings("java:S4266" /* This violation will be rewritten. */)
long before(Stream<T> stream) {
return stream.collect(counting());
}

@AfterTemplate
long after(Stream<T> stream) {
return stream.count();
}
}

static final class StreamReduce<T> {
@BeforeTemplate
@SuppressWarnings("java:S4266" /* This violation will be rewritten. */)
Optional<T> before(Stream<T> stream, BinaryOperator<T> accumulator) {
return stream.collect(reducing(accumulator));
}

@AfterTemplate
Optional<T> after(Stream<T> stream, BinaryOperator<T> accumulator) {
return stream.reduce(accumulator);
}
}

static final class StreamReduceWithIdentity<T> {
@BeforeTemplate
@SuppressWarnings("java:S4266" /* This violation will be rewritten. */)
T before(Stream<T> stream, T identity, BinaryOperator<T> accumulator) {
return stream.collect(reducing(identity, accumulator));
}

@AfterTemplate
T after(Stream<T> stream, T identity, BinaryOperator<T> accumulator) {
return stream.reduce(identity, accumulator);
}
}

static final class StreamFilterCollect<T, R> {
@BeforeTemplate
R before(
Stream<T> stream, Predicate<? super T> predicate, Collector<? super T, ?, R> collector) {
return stream.collect(filtering(predicate, collector));
}

@AfterTemplate
R after(
Stream<T> stream, Predicate<? super T> predicate, Collector<? super T, ?, R> collector) {
return stream.filter(predicate).collect(collector);
}
}

static final class StreamMapCollect<T, U, R> {
@BeforeTemplate
@SuppressWarnings("java:S4266" /* This violation will be rewritten. */)
R before(
Stream<T> stream,
Function<? super T, ? extends U> mapper,
Collector<? super U, ?, R> collector) {
return stream.collect(mapping(mapper, collector));
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While missing from SonarCloud's overview, we can add similar rules for filtering, flatMapping and summarizing*.

}

@AfterTemplate
R after(
Stream<T> stream,
Function<? super T, ? extends U> mapper,
Collector<? super U, ?, R> collector) {
return stream.map(mapper).collect(collector);
}
}

static final class StreamFlatMapCollect<T, U, R> {
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As Stream#collect and Stream#reduce both have two (or three) overloads, we could consider to add an extra type suffix, but we can also defer till at some point we have the name generator 😋.

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Up to you 🙃

@BeforeTemplate
R before(
Stream<T> stream,
Function<? super T, ? extends Stream<? extends U>> mapper,
Collector<? super U, ?, R> collector) {
return stream.collect(flatMapping(mapper, collector));
}

@AfterTemplate
R after(
Stream<T> stream,
Function<? super T, ? extends Stream<? extends U>> mapper,
Collector<? super U, ?, R> collector) {
return stream.flatMap(mapper).collect(collector);
}
}
}
98 changes: 86 additions & 12 deletions ...contrib/src/test/resources/tech/picnic/errorprone/refasterrules/StreamRulesTestInput.java
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Original file line number Diff line number Diff line change
@@ -1,12 +1,29 @@
package tech.picnic.errorprone.refasterrules;

import static com.google.common.collect.ImmutableSet.toImmutableSet;
import static java.util.Comparator.comparingInt;
import static java.util.Comparator.reverseOrder;
import static java.util.function.Predicate.not;
import static java.util.stream.Collectors.counting;
import static java.util.stream.Collectors.filtering;
import static java.util.stream.Collectors.flatMapping;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.mapping;
import static java.util.stream.Collectors.maxBy;
import static java.util.stream.Collectors.minBy;
import static java.util.stream.Collectors.reducing;
import static java.util.stream.Collectors.summarizingDouble;
import static java.util.stream.Collectors.summarizingInt;
import static java.util.stream.Collectors.summarizingLong;
import static java.util.stream.Collectors.summingDouble;
import static java.util.stream.Collectors.summingInt;
import static java.util.stream.Collectors.summingLong;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Streams;
import java.util.DoubleSummaryStatistics;
import java.util.IntSummaryStatistics;
import java.util.LongSummaryStatistics;
import java.util.Objects;
import java.util.Optional;
import java.util.function.Function;
Expand All @@ -17,7 +34,23 @@
final class StreamRulesTest implements RefasterRuleCollectionTestCase {
@Override
public ImmutableSet<Object> elidedTypesAndStaticImports() {
return ImmutableSet.of(Objects.class, Streams.class, not(null));
return ImmutableSet.of(
Objects.class,
Streams.class,
counting(),
filtering(null, null),
flatMapping(null, null),
mapping(null, null),
maxBy(null),
minBy(null),
not(null),
reducing(null),
summarizingDouble(null),
summarizingInt(null),
summarizingLong(null),
summingDouble(null),
summingInt(null),
summingLong(null));
}

String testJoining() {
Expand Down Expand Up @@ -90,7 +123,8 @@ ImmutableSet<Boolean> testStreamIsNotEmpty() {
ImmutableSet<Optional<String>> testStreamMin() {
return ImmutableSet.of(
Stream.of("foo").max(comparingInt(String::length).reversed()),
Stream.of("bar").sorted(comparingInt(String::length)).findFirst());
Stream.of("bar").sorted(comparingInt(String::length)).findFirst(),
Stream.of("baz").collect(minBy(comparingInt(String::length))));
}

ImmutableSet<Optional<String>> testStreamMinNaturalOrder() {
Expand All @@ -101,7 +135,8 @@ ImmutableSet<Optional<String>> testStreamMinNaturalOrder() {
ImmutableSet<Optional<String>> testStreamMax() {
return ImmutableSet.of(
Stream.of("foo").min(comparingInt(String::length).reversed()),
Streams.findLast(Stream.of("bar").sorted(comparingInt(String::length))));
Streams.findLast(Stream.of("bar").sorted(comparingInt(String::length))),
Stream.of("baz").collect(maxBy(comparingInt(String::length))));
}

ImmutableSet<Optional<String>> testStreamMaxNaturalOrder() {
Expand Down Expand Up @@ -143,24 +178,63 @@ boolean testStreamAllMatch2() {
ImmutableSet<Integer> testStreamMapToIntSum() {
Function<String, Integer> parseIntFunction = Integer::parseInt;
return ImmutableSet.of(
Stream.of(1).map(i -> i * 2).reduce(0, Integer::sum),
Stream.of("2").map(Integer::parseInt).reduce(0, Integer::sum),
Stream.of("3").map(parseIntFunction).reduce(0, Integer::sum));
Stream.of("1").collect(summingInt(Integer::parseInt)),
Stream.of(2).map(i -> i * 2).reduce(0, Integer::sum),
Stream.of("3").map(Integer::parseInt).reduce(0, Integer::sum),
Stream.of("4").map(parseIntFunction).reduce(0, Integer::sum));
}

ImmutableSet<Double> testStreamMapToDoubleSum() {
Function<String, Double> parseDoubleFunction = Double::parseDouble;
return ImmutableSet.of(
Stream.of(1).map(i -> i * 2.0).reduce(0.0, Double::sum),
Stream.of("2").map(Double::parseDouble).reduce(0.0, Double::sum),
Stream.of("3").map(parseDoubleFunction).reduce(0.0, Double::sum));
Stream.of("1").collect(summingDouble(Double::parseDouble)),
Stream.of(2).map(i -> i * 2.0).reduce(0.0, Double::sum),
Stream.of("3").map(Double::parseDouble).reduce(0.0, Double::sum),
Stream.of("4").map(parseDoubleFunction).reduce(0.0, Double::sum));
}

ImmutableSet<Long> testStreamMapToLongSum() {
Function<String, Long> parseLongFunction = Long::parseLong;
return ImmutableSet.of(
Stream.of(1).map(i -> i * 2L).reduce(0L, Long::sum),
Stream.of("2").map(Long::parseLong).reduce(0L, Long::sum),
Stream.of("3").map(parseLongFunction).reduce(0L, Long::sum));
Stream.of("1").collect(summingLong(Long::parseLong)),
Stream.of(2).map(i -> i * 2L).reduce(0L, Long::sum),
Stream.of("3").map(Long::parseLong).reduce(0L, Long::sum),
Stream.of("4").map(parseLongFunction).reduce(0L, Long::sum));
}

IntSummaryStatistics testStreamMapToIntSummaryStatistics() {
return Stream.of("1").collect(summarizingInt(Integer::parseInt));
}

DoubleSummaryStatistics testStreamMapToDoubleSummaryStatistics() {
return Stream.of("1").collect(summarizingDouble(Double::parseDouble));
}

LongSummaryStatistics testStreamMapToLongSummaryStatistics() {
return Stream.of("1").collect(summarizingLong(Long::parseLong));
}

Long testStreamCount() {
return Stream.of(1).collect(counting());
}

Optional<Integer> testStreamReduce() {
return Stream.of(1).collect(reducing(Integer::sum));
}

Integer testStreamReduceWithIdentity() {
return Stream.of(1).collect(reducing(0, Integer::sum));
}

ImmutableSet<String> testStreamFilterCollect() {
return Stream.of("1").collect(filtering(String::isEmpty, toImmutableSet()));
}

ImmutableSet<Integer> testStreamMapCollect() {
return Stream.of("1").collect(mapping(Integer::parseInt, toImmutableSet()));
}

ImmutableSet<Integer> testStreamFlatMapCollect() {
return Stream.of(1).collect(flatMapping(n -> Stream.of(n, n), toImmutableSet()));
}
}
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