efficient Range unions for #7435

eclipse-archived · Nov 19, 2018 · 817ad5b · xkr47 · Nov 20, 2018 · 817ad5b
1 parent 45a4ed1
commit 817ad5b
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Showing 4 changed files with 76 additions and 3 deletions.
diff --git a/language/src/ceylon/language/Range.ceylon b/language/src/ceylon/language/Range.ceylon
@@ -88,4 +88,66 @@ class Range<Element>()
     "Returns the range itself, since a range cannot contain 
      duplicate elements."
     shared actual Range<Element> distinct => this;
+
+    shared actual 
+    Set<Element|Other&Object> union<Other>
+            (Collection<Other> collection) 
+            => switch (collection) 
+            case (Range<Element>) Union<Element>(this, collection) 
+            case (Union<Element>) Union<Element>(this, *collection.ranges) 
+            else super.union(collection);
+
 }
+
+class Union<Element>(ranges) 
+        satisfies Set<Element> 
+        given Element satisfies Enumerable<Element> {
+
+	shared Range<Element>+ ranges;
+
+	function small(Range<Element> r) 
+			=> r.increasing then r.first else r.last;
+	function large(Range<Element> r) 
+			=> r.increasing then r.last else r.first;
+
+	function before(Element x, Element y)
+	        => x.offsetSign(y)<0;
+
+	value minval = ranges.fold(small(ranges.first), 
+		(p, r) => let (q=small(r))
+		if (before(p,q)) then p else q);
+	value maxval = ranges.fold(large(ranges.first), 
+		(p, r) => let (q=large(r))
+		if (before(p,q)) then q else p);
+
+    iterator() => object satisfies Iterator<Element> {
+        variable value current = minval;
+        shared actual Element|Finished next() {
+            if (before(maxval, current)) {
+                return finished;
+            }
+            value result = current;
+            while (!before(maxval, current)) {
+                current = current.successor;
+                if (current in outer) {
+                    break;
+                }
+            }
+            return result;
+        }
+    };
+
+    contains(Object element) => ranges.any((r) => element in r);
+
+    shared actual 
+    Set<Element|Other&Object> union<Other>
+            (Collection<Other> collection) 
+            => switch (collection) 
+            case (Range<Element>) Union<Element>(*ranges.withTrailing(collection))
+            case (Union<Element>) Union<Element>(*ranges.append(collection.ranges)) 
+            else super.union(collection);
+
+    equals(Object that) => (super of Set<Object>).equals(that);
+    hash => (super of Set<Object>).hash;
+
+}
diff --git a/language/test/lists.ceylon b/language/test/lists.ceylon
@@ -184,9 +184,6 @@ shared void lists() {
 
     mappedArraySequence();
 
-    check((1..2)|(4..5) == set{1,2,4,5}, "union");
-    check((1..3)&(3..5) == set{3}, "intersection");
-
 }
 
 shared void mappedArraySequence() {

diff --git a/language/test/range.ceylon b/language/test/range.ceylon
@@ -61,4 +61,11 @@ shared void testRange() {
     check((1..3)[1...]==2..3, "range span from");
     check((1..3)[1:1]==2..2, "range measure");
 
+    check(2 in (1..2)|(4..5), "range union");
+    check(!3 in (1..2)|(4..5), "range union");
+    check(4 in (1..2)|(4..5), "range union");
+
+    check((1..2)|(4..5) == set{1,2,4,5}, "range union");
+    check((1..3)&(3..5) == set{3}, "range intersection");
+
 }
diff --git a/language/test/sequences.ceylon b/language/test/sequences.ceylon
@@ -576,4 +576,11 @@ shared void sequences() {
     assert (is String[4] split);
     check(split == ["foo", "bar", "baz", "qux"], "tuple()");
 
+    check(2 in [1,2]|[4,5], "sequence union");
+    check(!3 in [1,2]|[4,5], "sequence union");
+    check(4 in [1,2]|[4,5], "sequence union");
+
+    check([1,2]|[4,5] == set{1,2,4,5}, "sequence union");
+    check([1,2,3]&[3,4,5] == set{3}, "sequence intersection");
+
 }