mirror of https://github.com/sbt/sbt.git
50 lines
1.4 KiB
Java
50 lines
1.4 KiB
Java
/* sbt -- Simple Build Tool
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* Copyright 2008, 2009, 2010 Mark Harrah
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*/
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package xsbti;
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/** Intended as a lightweight carrier for scala.Option. */
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public abstract class Maybe<t>
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{
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// private pending Scala bug #3642
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protected Maybe() {}
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public static <s> Maybe<s> just(final s v)
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{
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return new Maybe<s>() {
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public boolean isDefined() { return true; }
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public s get() { return v; }
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public int hashCode() { return 17 + (v == null ? 0 : v.hashCode()); }
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public String toString() { return "Maybe.just(" + v + ")"; }
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public boolean equals(Object o) {
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if (o == null) return false;
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if (!(o instanceof Maybe)) return false;
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Maybe<?> other = (Maybe<?>) o;
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if (!other.isDefined()) return false;
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if (v == null) return other.get() == null;
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return v.equals(other.get());
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}
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};
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}
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public static <s> Maybe<s> nothing()
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{
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return new Maybe<s>() {
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public boolean isDefined() { return false; }
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public s get() { throw new UnsupportedOperationException("nothing.get"); }
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public int hashCode() { return 1; }
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public String toString() { return "Maybe.nothing()"; }
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public boolean equals(Object o) {
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if (o == null) return false;
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if (!(o instanceof Maybe)) return false;
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Maybe<?> other = (Maybe<?>) o;
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return !other.isDefined();
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}
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};
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}
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public final boolean isEmpty() { return !isDefined(); }
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public abstract boolean isDefined();
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public abstract t get();
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}
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