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removed the create() methods; added linkedList<T>(varargs) helper method and made filter/flatMap/map all allow an optional argument for the kind of collection to filter/flatMap/map into. I've temporarily commented out Alex's implementation of Iterable.filter in Filters.kt as I was getting all kinds of compile error messages. Will discuss this on the list & how better to organise the functions into files

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This commit is contained in:
James Strachan
2011-12-20 16:28:18 +00:00
parent d37c6976b1
commit fee6bed2d4
5 changed files with 50 additions and 34 deletions
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stdlib/ktSrc/JavaUtil.kt
+12 -32
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@@ -18,6 +18,14 @@ inline fun arrayList<T>(vararg values: T) : ArrayList<T> {
return answer;
}
/** Returns a new LinkedList with a variable number of initial elements */
inline fun linkedList<T>(vararg values: T) : LinkedList<T> {
val answer = LinkedList<T>()
for (v in values)
answer.add(v)
return answer;
}
/** Returns a new HashSet with a variable number of initial elements */
inline fun hashSet<T>(vararg values: T) : HashSet<T> {
val answer = HashSet<T>()
@@ -26,25 +34,6 @@ inline fun hashSet<T>(vararg values: T) : HashSet<T> {
return answer;
}
/** Returns a new collection for the results of a helper method */
protected fun <T,R> java.lang.Iterable<T>.create(defaultSize: Int? = null) : Collection<R> {
if (defaultSize != null) {
return ArrayList<R>(defaultSize)
} else {
return ArrayList<R>()
}
}
protected fun <T,R> Set<T>.create(defaultSize: Int? = null) : Set<R> {
if (defaultSize != null) {
return HashSet<R>(defaultSize)
} else {
return HashSet<R>()
}
}
/** Returns true if any elements in the collection match the given predicate */
inline fun <T> java.lang.Iterable<T>.any(predicate: fun(T): Boolean) : Boolean {
for (elem in this) {
@@ -75,26 +64,19 @@ inline fun <T> java.lang.Iterable<T>.find(predicate: fun(T): Boolean) : T? {
}
/** Returns a new collection containing all elements in this collection which match the given predicate */
// TODO using: Collection<T> for the return type - I wonder if this exact type could be
// deduced somewhat from the This.Type; e.g. returning Set on a Set, Array on Array etc
/*
inline fun <T> java.lang.Iterable<T>.filter(predicate: fun(T): Boolean) : Collection<T> {
val result = this.create<T,T>()
inline fun <T> java.lang.Iterable<T>.filter(result: Collection<T> = ArrayList<T>(), predicate: fun(T): Boolean) : Collection<T> {
for (elem in this) {
if (predicate(elem))
result.add(elem)
}
return result
}
*/
/**
* Returns the result of transforming each item in the collection to a one or more values which
* are concatenated together into a single collection
*/
// TODO should use Iterable instead of Collection in transform?
inline fun <T, out R> java.lang.Iterable<T>.flatMap(transform: fun(T): Collection<R>) : Collection<R> {
val result = this.create<T,R>()
inline fun <T, out R> java.lang.Iterable<T>.flatMap(result: Collection<R> = ArrayList<R>(), transform: fun(T): Collection<R>) : Collection<R> {
for (elem in this) {
val coll = transform(elem)
if (coll != null) {
@@ -128,16 +110,14 @@ inline fun <T> java.lang.Iterable<T>.join(separator: String, prefix: String = ""
}
/** Returns a new collection containing the results of applying the given function to each element in this collection */
inline fun <T, R> java.lang.Iterable<T>.map(transform : fun(T) : R) : Collection<R> {
val result = this.create<T,R>()
inline fun <T, R> java.lang.Iterable<T>.map(result: Collection<R> = ArrayList<R>(), transform : fun(T) : R) : Collection<R> {
for (item in this)
result.add(transform(item))
return result
}
/** Returns a new collection containing the results of applying the given function to each element in this collection */
inline fun <T, R> java.util.Collection<T>.map(transform : fun(T) : R) : Collection<R> {
val result = this.create<T,R>(this.size)
inline fun <T, R> java.util.Collection<T>.map(result: Collection<R> = ArrayList<R>(this.size), transform : fun(T) : R) : Collection<R> {
for (item in this)
result.add(transform(item))
return result