Changeset 1566

Timestamp:

05/29/10 13:43:59 (15 years ago)

Author:

rsinfu

Message:

Fixed bugzilla 3876: std.range.Take back/popBack methods don't work correctly.
Thanks to Philippe Sigaud for the proposed solution. It was helpful.

The former implementation simply used input.back for Take.back. It didn't work if input.length was larger than maxAvailable. For example:

input = [ 1, 2, 3, 4, 5 ]
s = take(input, 3) // [ 1, 2, 3 ]
s.back == input.back == 5 // wrong!

Take must pop all the excess elements from the input ([4,5] in the above example) to provide correct back element. This change makes it to do so if input is purely bidirectional. (random access is used instead if possible.)

- Added Take.opSlice
- Added some enforcement error messages

Files:

• trunk/docsrc/changelog.dd (modified) (1 diff)
• trunk/phobos/std/range.d (modified) (1 diff)

trunk/docsrc/changelog.dd

@@ -12 +12 @@
-    )
-    $(BUGSFIXED
-    $(LI $(BUGZILLA 2738): Rebindable should work for interfaces.)
-    $(LI $(BUGZILLA 2835): std.socket.TcpSocket doesn't actually connect)
-    $(LI $(BUGZILLA 3088): std.xml.check() fails on xml comments)
-    $(LI $(BUGZILLA 3200): std.xml doesn't follow spec for Tag.text)
-    $(LI $(BUGZILLA 3465): isIdeographic can be wrong in std.xml)
-    $(LI $(BUGZILLA 3653): Problem sorting array of Rebindable)
-    $(LI $(BUGZILLA 3786): bug in std.string.removechars)
-    $(LI $(BUGZILLA 3873): std.range.repeat should have popBack defined)
+    $(LI $(BUGZILLA 3876): std.range.Take back/popBack methods don't work correctly)
-    $(LI $(BUGZILLA 3880): std.regex functions with const/immutable Regex object)
-    $(LI $(BUGZILLA 4109): writeln doesn't work with empty static array)
-    $(LI $(BUGZILLA 4188): std.file.remove throws Exception on success)
-    $(LI $(BUGZILLA 4202): Changset 1517 doesn't compile)
-    $(LI $(BUGZILLA 4228): std.array.replace contains 2 bugs)
-    $(LI $(BUGZILLA 4219): hasAliasing does not care about immutable)
-    )
-)
-
-<div id=version>

trunk/phobos/std/range.d

@@ -1188 +1188 @@
-assert(s[4] == 5);
-assert(equal(s, [ 1, 2, 3, 4, 5 ][]));
-----
- */
-
-struct Take(R) if (isInputRange!(R))
-{
-private:
-    R _input;
-    size_t _maxAvailable;
-
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-
-public:
-    alias R Source;
-
-    static if (byRef)
-        alias ref .ElementType!(R) ElementType;
-    else
-        alias .ElementType!(R) ElementType;
-
+    this(R input, size_t maxAvailable)
+    {
+        static if (backByBack)
+        {
+            while (input.length > maxAvailable)
+                input.popBack;
+        }
+        _input = input;
+        _maxAvailable = maxAvailable;
+    }
+
-    bool empty()
-    {
-        return _maxAvailable == 0 || _input.empty;
-    }
-
-    void popFront()
-    {
-
+
+
+
-        _input.popFront;
-        --_maxAvailable;
-    }
-
-    // @@@@@@@@@@@ UGLY @@@@@@@@@@@@@@@
-    mixin(
-        (byRef ? "ref " : "")~
-        q{ElementType front()
-        {
-
+
+
+
-            return _input.front;
-        }});
-
-    static if (isInfinite!(R))
-    {
-        @property size_t length() const
-        {
-            return _maxAvailable;
-        }
-
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-        void popBack()
-        {
-
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-            --_maxAvailable;
-        }
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-        mixin(
-            (byRef ? "ref " : "")~
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-        mixin(
-            (byRef ? "ref " : "")~
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-        mixin(
-            (byRef ? "ref " : "")~
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-}
-
-/// Ditto
-Take!(R) take(R)(R input, size_t n) if (isInputRange!(R))
-{
-    return Take!(R)(input, n);
-}
-
-unittest
-{
-    int[] arr1 = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ];
-    auto s = take(arr1, 5);
-    assert(s.length == 5);
-    assert(s[4] == 5);
-    assert(equal(s, [ 1, 2, 3, 4, 5 ][]));
+    assert(equal(retro(s), [ 5, 4, 3, 2, 1 ][]));
-}
-
-/**
-Eagerly advances $(D r) itself (not a copy) $(D n) times (by calling
-$(D r.popFront) $(D n) times). The pass of $(D r) into $(D popFrontN)
-is by reference, so the original range is affected. Completes in
-$(BIGOH 1) steps for ranges that support slicing, and in $(BIGOH n)
-time for all other ranges.
-
-Example: