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// Copyright 2014 Google Inc. All rights reserved.
//
// Licensed 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 com.google.devtools.build.lib.rules.objc;
import com.google.common.base.Function;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
/**
* Utility code for interspersing items into sequences.
*/
public class Interspersing {
private Interspersing() {}
/**
* Inserts {@code what} before each item in {@code sequence}, returning a lazy sequence of twice
* the length.
*/
public static <E> Iterable<E> beforeEach(final E what, Iterable<E> sequence) {
Preconditions.checkNotNull(what);
return Iterables.concat(
Iterables.transform(
sequence,
new Function<E, Iterable<E>>() {
@Override
public Iterable<E> apply(E element) {
return ImmutableList.of(what, element);
}
}
));
}
/**
* Prepends {@code what} to each string in {@code sequence}, returning a lazy sequence of the
* same length.
*/
public static Iterable<String>
prependEach(final String what, Iterable<String> sequence) {
Preconditions.checkNotNull(what);
return Iterables.transform(
sequence,
new Function<String, String>() {
@Override
public String apply(String input) {
return what + input;
}
});
}
/**
* Similar to {@link #prependEach(String, Iterable)}, but also converts each item in the sequence
* to a string.
*/
public static <E> Iterable<String>
prependEach(String what, Iterable<E> sequence, Function<? super E, String> toString) {
return prependEach(what, Iterables.transform(sequence, toString));
}
}
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