[GitHub] incubator-groovy pull request: Changed the Range's step to Number ...

[paplorinc <gi...@git.apache.org>]

GitHub user paplorinc opened a pull request:

    https://github.com/apache/incubator-groovy/pull/120

    Changed the Range's step to Number instead of int

    Until now a range could only step by an integer value, even if its elements had other types, e.g. doubles.
    This made stepping over ranges like `0.1..0.9`strange, as that resulted in a single element.
    
    Also, stepping over `ObjectRange` instances (like the above one) called the `next`/`previous` method reflectively,
    even if the range had a numeric type (the most common case).
    This made it ~10x slower than e.g. `IntRange`.
    
    The new implementation changed the `step` type to `Number` and unified the way stepping is done in
    `ObjectRange` and `IntRange`, making them equally fast (close to the original `IntRange` speed)
    for numeric cases.
    
    Also, `IntRange` treats the overflow issue by storing the intermediary value in a `long` directly.
    
    
    -------------------
    
    I tested the speed via the following trivial method:
    
    ```Groovy
    void testSpeed() {
        for (def i = 0; i < 10; i++)
            run()
    }
    
    private void run() {
        def time = System.currentTimeMillis()
        def size = 0G
        for (def i = 0; i < 100; i++) { // changed to `i = 0G` when testing ObjectRange
            for (def j = 0; j < 100; j++) {
                def range = i..j
                def inverseRange = j..i
                for (def k = 1; k < 100; k++) {
                    size += range.step(k).size()
                    size += range.step(-k).size()
    
                    size += inverseRange.step(k).size()
                    size += inverseRange.step(-k).size()
                }
            }
        }
        println "size = ${size} in ${(System.currentTimeMillis() - time) / 1000.0}s"
    }
    ```
    
    resulting in
    ```
    * Old impl for ObjectRange: `66.30s`
    * New impl for ObjectRange: `5.52s` (12 times faster)
    ```
    and
    ```
    * Old impl for IntRange: `4.54s`
    * New impl for IntRange: `4.97s` (0.91 times faster)
    ```

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/paplorinc/incubator-groovy RangeNumberStepSize

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/incubator-groovy/pull/120.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #120
    
----
commit 905ccfc0cfa848eea45e3d33f3dc542a40512d2a
Author: Pap Lőrinc <pa...@yahoo.com>
Date:   2015-09-17T19:45:24Z

    Changed the Range's step to Number instead of int
    
    Until now a range could only step by an integer value, even if its elements had other types, e.g. doubles.
    This made stepping over ranges like `0.1..0.9`strange, as that resulted in a single element.
    
    Also, stepping over `ObjectRange` instances (like the above one) called the `next`/`previous` method reflectively,
    even if the range had a numeric type (the most common case).
    This made it ~10x slower than e.g. `IntRange`.
    
    The new implementation changed the `step` type to `Number` and unified the way stepping is done in
    `ObjectRange` and `IntRange`, making them equally fast (close to the original `IntRange` speed)
    for numeric cases.
    
    Also, `IntRange` treats the overflow issue by storing the intermediary value in a `long` directly.

----


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