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bors 09ee9b723a Auto merge of #44856 - cuviper:more-fold, r=dtolnay
Add more custom folding to `core::iter` adaptors

Many of the iterator adaptors will perform faster folds if they forward
to their inner iterator's folds, especially for inner types like `Chain`
which are optimized too.  The following types are newly specialized:

| Type        | `fold` | `rfold` |
| ----------- | ------ | ------- |
| `Enumerate` | ✓      | ✓       |
| `Filter`    | ✓      | ✓       |
| `FilterMap` | ✓      | ✓       |
| `FlatMap`   | exists | ✓       |
| `Fuse`      | ✓      | ✓       |
| `Inspect`   | ✓      | ✓       |
| `Peekable`  | ✓      | N/A¹    |
| `Skip`      | ✓      | N/A²    |
| `SkipWhile` | ✓      | N/A¹    |

¹ not a `DoubleEndedIterator`

² `Skip::next_back` doesn't pull skipped items at all, but this couldn't
be avoided if `Skip::rfold` were to call its inner iterator's `rfold`.

Benchmarks
----------

In the following results, plain `_sum` computes the sum of a million
integers -- note that `sum()` is implemented with `fold()`.  The
`_ref_sum` variants do the same on a `by_ref()` iterator, which is
limited to calling `next()` one by one, without specialized `fold`.

The `chain` variants perform the same tests on two iterators chained
together, to show a greater benefit of forwarding `fold` internally.

    test iter::bench_enumerate_chain_ref_sum  ... bench:   2,216,264 ns/iter (+/- 29,228)
    test iter::bench_enumerate_chain_sum      ... bench:     922,380 ns/iter (+/- 2,676)
    test iter::bench_enumerate_ref_sum        ... bench:     476,094 ns/iter (+/- 7,110)
    test iter::bench_enumerate_sum            ... bench:     476,438 ns/iter (+/- 3,334)

    test iter::bench_filter_chain_ref_sum     ... bench:   2,266,095 ns/iter (+/- 6,051)
    test iter::bench_filter_chain_sum         ... bench:     745,594 ns/iter (+/- 2,013)
    test iter::bench_filter_ref_sum           ... bench:     889,696 ns/iter (+/- 1,188)
    test iter::bench_filter_sum               ... bench:     667,325 ns/iter (+/- 1,894)

    test iter::bench_filter_map_chain_ref_sum ... bench:   2,259,195 ns/iter (+/- 353,440)
    test iter::bench_filter_map_chain_sum     ... bench:   1,223,280 ns/iter (+/- 1,972)
    test iter::bench_filter_map_ref_sum       ... bench:     611,607 ns/iter (+/- 2,507)
    test iter::bench_filter_map_sum           ... bench:     611,610 ns/iter (+/- 472)

    test iter::bench_fuse_chain_ref_sum       ... bench:   2,246,106 ns/iter (+/- 22,395)
    test iter::bench_fuse_chain_sum           ... bench:     634,887 ns/iter (+/- 1,341)
    test iter::bench_fuse_ref_sum             ... bench:     444,816 ns/iter (+/- 1,748)
    test iter::bench_fuse_sum                 ... bench:     316,954 ns/iter (+/- 2,616)

    test iter::bench_inspect_chain_ref_sum    ... bench:   2,245,431 ns/iter (+/- 21,371)
    test iter::bench_inspect_chain_sum        ... bench:     631,645 ns/iter (+/- 4,928)
    test iter::bench_inspect_ref_sum          ... bench:     317,437 ns/iter (+/- 702)
    test iter::bench_inspect_sum              ... bench:     315,942 ns/iter (+/- 4,320)

    test iter::bench_peekable_chain_ref_sum   ... bench:   2,243,585 ns/iter (+/- 12,186)
    test iter::bench_peekable_chain_sum       ... bench:     634,848 ns/iter (+/- 1,712)
    test iter::bench_peekable_ref_sum         ... bench:     444,808 ns/iter (+/- 480)
    test iter::bench_peekable_sum             ... bench:     317,133 ns/iter (+/- 3,309)

    test iter::bench_skip_chain_ref_sum       ... bench:   1,778,734 ns/iter (+/- 2,198)
    test iter::bench_skip_chain_sum           ... bench:     761,850 ns/iter (+/- 1,645)
    test iter::bench_skip_ref_sum             ... bench:     478,207 ns/iter (+/- 119,252)
    test iter::bench_skip_sum                 ... bench:     315,614 ns/iter (+/- 3,054)

    test iter::bench_skip_while_chain_ref_sum ... bench:   2,486,370 ns/iter (+/- 4,845)
    test iter::bench_skip_while_chain_sum     ... bench:     633,915 ns/iter (+/- 5,892)
    test iter::bench_skip_while_ref_sum       ... bench:     666,926 ns/iter (+/- 804)
    test iter::bench_skip_while_sum           ... bench:     444,405 ns/iter (+/- 571)
2017-09-29 12:56:24 +00:00
src Auto merge of #44856 - cuviper:more-fold, r=dtolnay 2017-09-29 12:56:24 +00:00
.gitattributes fix gitattributes for vendor 2017-02-13 13:41:13 -05:00
.gitignore Allow writing metadata without llvm 2017-09-23 12:54:53 +02:00
.gitmodules Get the miri test suite to run inside the rustc dev environment 2017-09-17 21:40:13 +02:00
.mailmap Rollup merge of #43846 - frewsxcv:frewsxcv-mailmap, r=Mark-Simulacrum 2017-08-14 20:28:45 -04:00
.travis.yml Rollup merge of #44617 - alexcrichton:download-from-us-west-1, r=aidanhs 2017-09-17 13:19:11 +02:00
CODE_OF_CONDUCT.md Tweak the CoC to point to the online version. 2017-07-12 12:42:54 -04:00
CONTRIBUTING.md Rollup merge of #44776 - spastorino:add_forge, r=nikomatsakis 2017-09-23 00:29:22 -04:00
COPYRIGHT COPYRIGHT: Provide a better explanation of Rust copyrights 2017-07-26 16:52:15 -07:00
LICENSE-APACHE Update license, add license boilerplate to most files. Remainder will follow. 2012-12-03 17:12:14 -08:00
LICENSE-MIT LICENSE-MIT: Remove inaccurate (misattributed) copyright notice 2017-07-26 16:51:58 -07:00
README.md Clarify windows build instructions in README 2017-08-22 13:28:39 -05:00
RELEASES.md Fix link typo in 1.20.0 release notes 2017-09-05 12:27:14 +08:00
appveyor.yml Rollup merge of #44617 - alexcrichton:download-from-us-west-1, r=aidanhs 2017-09-17 13:19:11 +02:00
config.toml.example Get the miri test suite to run inside the rustc dev environment 2017-09-17 21:40:13 +02:00
configure rustbuild: Rewrite the configure script in Python 2017-08-27 18:53:30 -07:00
x.py Rename os variable in bootstrap.py to avoid shadowing os module. 2017-04-30 16:10:31 -04:00

README.md

The Rust Programming Language

This is the main source code repository for Rust. It contains the compiler, standard library, and documentation.

Quick Start

Read "Installation" from The Book.

Building from Source

  1. Make sure you have installed the dependencies:

    • g++ 4.7 or later or clang++ 3.x or later
    • python 2.7 (but not 3.x)
    • GNU make 3.81 or later
    • cmake 3.4.3 or later
    • curl
    • git
  2. Clone the source with git:

    $ git clone https://github.com/rust-lang/rust.git
    $ cd rust
    
  1. Build and install:

    $ ./x.py build && sudo ./x.py install
    

    Note: Install locations can be adjusted by copying the config file from ./config.toml.example to ./config.toml, and adjusting the prefix option under [install]. Various other options, such as enabling debug information, are also supported, and are documented in the config file.

    When complete, sudo ./x.py install will place several programs into /usr/local/bin: rustc, the Rust compiler, and rustdoc, the API-documentation tool. This install does not include Cargo, Rust's package manager, which you may also want to build.

Building on Windows

There are two prominent ABIs in use on Windows: the native (MSVC) ABI used by Visual Studio, and the GNU ABI used by the GCC toolchain. Which version of Rust you need depends largely on what C/C++ libraries you want to interoperate with: for interop with software produced by Visual Studio use the MSVC build of Rust; for interop with GNU software built using the MinGW/MSYS2 toolchain use the GNU build.

MinGW

MSYS2 can be used to easily build Rust on Windows:

  1. Grab the latest MSYS2 installer and go through the installer.

  2. Run mingw32_shell.bat or mingw64_shell.bat from wherever you installed MSYS2 (i.e. C:\msys64), depending on whether you want 32-bit or 64-bit Rust. (As of the latest version of MSYS2 you have to run msys2_shell.cmd -mingw32 or msys2_shell.cmd -mingw64 from the command line instead)

  3. From this terminal, install the required tools:

    # Update package mirrors (may be needed if you have a fresh install of MSYS2)
    $ pacman -Sy pacman-mirrors
    
    # Install build tools needed for Rust. If you're building a 32-bit compiler,
    # then replace "x86_64" below with "i686". If you've already got git, python,
    # or CMake installed and in PATH you can remove them from this list. Note
    # that it is important that you do **not** use the 'python2' and 'cmake'
    # packages from the 'msys2' subsystem. The build has historically been known
    # to fail with these packages.
    $ pacman -S git \
                make \
                diffutils \
                tar \
                mingw-w64-x86_64-python2 \
                mingw-w64-x86_64-cmake \
                mingw-w64-x86_64-gcc
    
  4. Navigate to Rust's source code (or clone it), then build it:

    $ ./x.py build && ./x.py install
    

MSVC

MSVC builds of Rust additionally require an installation of Visual Studio 2013 (or later) so rustc can use its linker. Make sure to check the “C++ tools” option.

With these dependencies installed, you can build the compiler in a cmd.exe shell with:

> python x.py build

Currently building Rust only works with some known versions of Visual Studio. If you have a more recent version installed the build system doesn't understand then you may need to force rustbuild to use an older version. This can be done by manually calling the appropriate vcvars file before running the bootstrap.

CALL "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\amd64\vcvars64.bat"
python x.py build

Specifying an ABI

Each specific ABI can also be used from either environment (for example, using the GNU ABI in powershell) by using an explicit build triple. The available Windows build triples are:

  • GNU ABI (using GCC)
    • i686-pc-windows-gnu
    • x86_64-pc-windows-gnu
  • The MSVC ABI
    • i686-pc-windows-msvc
    • x86_64-pc-windows-msvc

The build triple can be specified by either specifying --build=<triple> when invoking x.py commands, or by copying the config.toml file (as described in Building From Source), and modifying the build option under the [build] section.

Configure and Make

While it's not the recommended build system, this project also provides a configure script and makefile (the latter of which just invokes x.py).

$ ./configure
$ make && sudo make install

When using the configure script, the generated config.mk file may override the config.toml file. To go back to the config.toml file, delete the generated config.mk file.

Building Documentation

If youd like to build the documentation, its almost the same:

$ ./x.py doc

The generated documentation will appear under doc in the build directory for the ABI used. I.e., if the ABI was x86_64-pc-windows-msvc, the directory will be build\x86_64-pc-windows-msvc\doc.

Notes

Since the Rust compiler is written in Rust, it must be built by a precompiled "snapshot" version of itself (made in an earlier state of development). As such, source builds require a connection to the Internet, to fetch snapshots, and an OS that can execute the available snapshot binaries.

Snapshot binaries are currently built and tested on several platforms:

Platform / Architecture x86 x86_64
Windows (7, 8, Server 2008 R2)
Linux (2.6.18 or later)
OSX (10.7 Lion or later)

You may find that other platforms work, but these are our officially supported build environments that are most likely to work.

Rust currently needs between 600MiB and 1.5GiB to build, depending on platform. If it hits swap, it will take a very long time to build.

There is more advice about hacking on Rust in CONTRIBUTING.md.

Getting Help

The Rust community congregates in a few places:

Contributing

To contribute to Rust, please see CONTRIBUTING.

Rust has an IRC culture and most real-time collaboration happens in a variety of channels on Mozilla's IRC network, irc.mozilla.org. The most popular channel is #rust, a venue for general discussion about Rust. And a good place to ask for help would be #rust-beginners.

License

Rust is primarily distributed under the terms of both the MIT license and the Apache License (Version 2.0), with portions covered by various BSD-like licenses.

See LICENSE-APACHE, LICENSE-MIT, and COPYRIGHT for details.