Bug 9119 – [AA] Forward range addition to associative arrays.

Providing a forward range to associative arrays would allow user to use functionalities like "filter" and make their own (that return intelligent ranges instead of eagerly constructing a result, then returning said result or a range on it). It could be provided as a "range" property and "front" could return an entry struct where entry.key is the key and entry.value is the value. Example usage: float[ Item ] itemsCost; auto cheapItems = itemsCost.range.filter!"a.value < 5"(); foreach( cheap; cheapItems ) { sendGiftToEnemy( cheap.key ); }

See Issue 5075

Using the code in the pull request, this code works: import std.algorithm; import std.conv; import std.stdio: writeln; void main () { int[string] aa; aa["a"] = 1; aa["b"] = 2; aa["c"] = 3; writeln(aa.byPair .map!((a) => "key=" ~ a.key ~ " value=" ~ to!string(a.value)) .joiner("\n") ); } The output is: key=a value=1 key=b value=2 key=c value=3

Commit pushed to master at https://github.com/D-Programming-Language/druntime https://github.com/D-Programming-Language/druntime/commit/5933725ccc9f55564cf9cd1eecb32f98cbf3aa71 Merge pull request #1070 from quickfur/issue9119 Implement AA byPair.

Commit pushed to master at https://github.com/D-Programming-Language/dlang.org https://github.com/D-Programming-Language/dlang.org/commit/74e226ccb7e7f6e8967a8e9c00735d01a9676be5 Merge pull request #743 from quickfur/issue9119 Document AA .byKeyValue().

Commit pushed to master at https://github.com/D-Programming-Language/druntime https://github.com/D-Programming-Language/druntime/commit/b3a8032e3960480a1588b3d1a4491808b4502d67 Merge pull request #1077 from quickfur/issue9119_fixup Fix wrong copy-pasta from object_.d.

The printing of such key-value pairs is not very good. I don't know if you want to improve this, or leave the better printing to byPair: void main() { import std.stdio, std.algorithm; auto aa = [1:2, 3:4]; aa.byKeyValue.writeln; } [Pair(1513FE8, 1513FEC), Pair(1513FC8, 1513FCC)] ----------------- There are also problems with a constant key-value pair: void main() { auto aa = [1:2, 3:4]; foreach (const t; aa.byKeyValue) { auto k = t.key; auto v = t.value; } } test.d(4,18): Error: mutable method object.byKeyValue!(int[int], int, int).byKeyValue.Result.front.Pair.key is not callable using a const object test.d(5,18): Error: mutable method object.byKeyValue!(int[int], int, int).byKeyValue.Result.front.Pair.value is not callable using a const object -----------------

Commit pushed to master at https://github.com/D-Programming-Language/druntime https://github.com/D-Programming-Language/druntime/commit/9ec46a649e5fcd112dec7af102b4cab9189b48f3 Merge pull request #1079 from quickfur/issue9119_const byKeyValue should also work with const loop variables.

Commit pushed to master at https://github.com/D-Programming-Language/druntime https://github.com/D-Programming-Language/druntime/commit/841c9a68cc209aa2abcab95593dce5f9e777b4c3 Merge pull request #1080 from quickfur/issue9119_fwdrange .save needs to be @property otherwise isForwardRange fails.

Commit pushed to master at https://github.com/D-Programming-Language/dlang.org https://github.com/D-Programming-Language/dlang.org/commit/a61963ea2dbb96298137936c04551b38bd64feab Merge pull request #745 from quickfur/issue9119_changelog Document byKeyValue in changelog.

Commit pushed to master at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/88722a83e2a12db9e796d049ac9787518577cc50 Merge pull request #2842 from quickfur/issue9119_byPair Implement byPair.

Now that all the PR's have merged, here's the current situation: - druntime now provides a byKeyValue method that returns a forward range of opaque structs with .key and .value members. - std.array in Phobos now provides a "nice" method byPair that wraps around byKeyValue and returns a forward range of Tuple's of keys and values. So this both satisfies the OP's original request (for .key and .value) and later requests for Tuple compatibility.

Furthermore, printing of the range returned by byPair() produces output of the form: ----- immutable(Tuple!(string, int))("a", 123) immutable(Tuple!(string, int))("b", 234) immutable(Tuple!(string, int))("c", 345) ----- So the printing issue is also taken care of.

(In reply to hsteoh from comment #12) > So this both satisfies the OP's original request (for .key and .value) and > later requests for Tuple compatibility. Yes, of all the possible solutions, I think the current is one of the few acceptable ones. One point worth studying is the run-time efficiency of using byPair using the dmd compiler. I have seen a slowdown compared to using byKeyValue (but I have not done formal benchamarks).

Commits pushed to 2.067 at https://github.com/D-Programming-Language/druntime https://github.com/D-Programming-Language/druntime/commit/5933725ccc9f55564cf9cd1eecb32f98cbf3aa71 Merge pull request #1070 from quickfur/issue9119 https://github.com/D-Programming-Language/druntime/commit/b3a8032e3960480a1588b3d1a4491808b4502d67 Merge pull request #1077 from quickfur/issue9119_fixup https://github.com/D-Programming-Language/druntime/commit/9ec46a649e5fcd112dec7af102b4cab9189b48f3 Merge pull request #1079 from quickfur/issue9119_const https://github.com/D-Programming-Language/druntime/commit/841c9a68cc209aa2abcab95593dce5f9e777b4c3 Merge pull request #1080 from quickfur/issue9119_fwdrange

Commit pushed to 2.067 at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/88722a83e2a12db9e796d049ac9787518577cc50 Merge pull request #2842 from quickfur/issue9119_byPair