| commit | fa2fd41166db35afa4777e63f900e83d25709c5c | [log] [tgz] |
|---|---|---|
| author | Aske Simon Christensen <askesc@google.com> | Mon May 04 10:48:32 2020 +0000 |
| committer | commit-bot@chromium.org <commit-bot@chromium.org> | Mon May 04 10:48:32 2020 +0000 |
| tree | 376b3183de1be2d2592cd3946ffc0441c4e87051 | |
| parent | f372084f82ee36741803ad1d61e995d9cf971586 [diff] |
UTF-8 decoder using a state machine. Two-pass decoder: the first pass scans through the input to compute the length of the resulting string and which decoder to use, and the second pass does the actual decoding. The same decoder is used for both one-shot and chunked decoding, and both with and without allowMalformed. If there is an error in the input and allowMalformed is true, it starts over with a general decoder that supports malformed input and allocates space as it goes along. JS targets go directly to the general decoder, as the two-pass approach is not beneficial here. Three pieces of the decoder are designed to be pluggable by patches to optimize the performance further: - scan, running the first pass of the conversion. - decode8, decoding Latin1 data into a OneByteString. - decode16, decoding arbitrary data into a TwoByteString. Improves decoding speed, especially for complex input (many multi-byte characters). Observed speed increases are approximately: - dart2js: up to 40% - VM JIT: up to 260% - VM AOT: up to 130% The constant overhead of calling the UTF-8 decoder is also significantly reduced for dart2js. Code size for dart2js is slightly reduced compared to the old decoder. ASCII inputs currently see a slight speed decrease for VM targets, which will be fixed in https://dart-review.googlesource.com/c/sdk/+/145460 This is part of the implementation of the breaking change described at https://github.com/dart-lang/sdk/issues/41100 Closes https://github.com/dart-lang/sdk/issues/28832 Closes https://github.com/dart-lang/sdk/issues/31954 Ideas for further improvements to the decoder are collected in https://github.com/dart-lang/sdk/issues/41734 Change-Id: I3c5bb84e8d6783231680a9d34d6c38e8a28ab112 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/142025 Reviewed-by: Stephen Adams <sra@google.com> Reviewed-by: Martin Kustermann <kustermann@google.com>
Dart is:
Optimized for UI: Develop with a programming language specialized around the needs of user interface creation
Productive: Make changes iteratively: use hot reload to see the result instantly in your running app
Fast on all platforms: Compile to ARM & x64 machine code for mobile, desktop, and backend. Or compile to JavaScript for the web
Dart's flexible compiler technology lets you run Dart code in different ways, depending on your target platform and goals:
Dart Native: For programs targeting devices (mobile, desktop, server, and more), Dart Native includes both a Dart VM with JIT (just-in-time) compilation and an AOT (ahead-of-time) compiler for producing machine code.
Dart Web: For programs targeting the web, Dart Web includes both a development time compiler (dartdevc) and a production time compiler (dart2js).
Dart is free and open source.
See LICENSE and PATENT_GRANT.
Visit the dart.dev to learn more about the language, tools, getting started, and more.
Browse pub.dev for more packages and libraries contributed by the community and the Dart team.
If you want to build Dart yourself, here is a guide to getting the source, preparing your machine to build the SDK, and building.
There are more documents on our wiki.
The easiest way to contribute to Dart is to file issues.
You can also contribute patches, as described in Contributing.