3bede9fd31
This is my first non-docs contribution to Rust, so please let me know what I can fix. I probably should've submitted this to the mailing list first for comments, but it didn't take too long to implement so I figured I'd just give it a shot. These changes are modeled loosely on the [JsonNode API](http://jackson.codehaus.org/1.7.9/javadoc/org/codehaus/jackson/JsonNode.html) provided by the [Jackson JSON processor](http://jackson.codehaus.org/). Many common use cases for parsing JSON involve pulling one or more fields out of an object, however deeply nested. At present, this requires writing a pyramid of match statements. The added methods in this PR aim to make this a more painless process. **Edited to reflect final implementation** Example JSON: ```json { "successful" : true, "status" : 200, "error" : null, "content" : { "vehicles" : [ {"make" : "Toyota", "model" : "Camry", "year" : 1997}, {"make" : "Honda", "model" : "Accord", "year" : 2003} ] } } ``` Accessing "successful": ```rust let example_json : Json = from_str("...above json...").unwrap(); let was_successful: Option<bool> = example_json.find(&~"successful").and_then(|j| j.as_boolean()); ``` Accessing "status": ```rust let example_json : Json = from_str("...above json...").unwrap(); let status_code : Option<f64> = example_json.find(&~"status").and_then(|j| j.as_number()); ``` Accessing "vehicles": ```rust let example_json : Json = from_str("...above json...").unwrap(); let vehicle_list: Option<List> = example_json.search(&~"vehicles").and_then(|j| j.as_list()); ``` Accessing "vehicles" with an explicit path: ```rust let example_json : Json = from_str("...above json...").unwrap(); let vehicle_list: Option<List> = example_json.find_path(&[&~"content", &~"vehicles"]).and_then(|j| j.as_list()); ``` Accessing "error", which might be null or a string: ```rust let example_json : Json = from_str("...above json...").unwrap(); let error: Option<Json> = example_json.find(&~"error"); if error.is_null() { // This would be nicer as a match, I'm just illustrating the boolean test methods println!("Error is null, everything's fine."); } else if error.is_str(){ println!("Something went wrong: {}", error.as_string().unwrap()); } ``` Some notes: * Macros would help to eliminate some of the repetitiveness of the implementation, but I couldn't use them due to #4621. (**Edit**: There is no longer repetitive impl. Methods were simplified to make them more composable.) * Would it be better to name methods after the Json enum type (e.g. `get_string`) or the associated Rust built-in? (e.g. `get_str`) * TreeMap requires its keys to be &~str. Because of this, all of the new methods required &~str for their parameters. I'm uncertain what the best approach to fixing this is: neither demanding an owned pointer nor allocating within the methods to appease TreeMap's find() seems desirable. If I were able to take &str, people could put together paths easily with `"foo.bar.baz".split('.').collect();` (**Edit**: Follow on investigation into making TreeMap able to search by Equiv would be worthwhile.) * At the moment, the `find_<sometype>` methods all find the first match for the provided key and attempt to return that value if it's of the specified type. This makes sense to me, but it's possible that users would interpret a call to `find_boolean("successful")` as looking for the first "successful" item that was a boolean rather than looking for the first "successful" and returning None if it isn't boolean. (**Edit**: No longer relevant.) I hope this is helpful. Any feedback is appreciated!
The Rust Programming Language
This is a compiler for Rust, including standard libraries, tools and documentation.
Quick Start
Windows
- Download and use the installer and MinGW.
- Read the tutorial.
- Enjoy!
Note: Windows users can read the detailed getting started notes on the wiki.
Linux / OS X
-
Make sure you have installed the dependencies:
g++4.4 orclang++3.xpython2.6 or later (but not 3.x)perl5.0 or later- GNU
make3.81 or later curl
-
Download and build Rust:
You can either download a tarball or build directly from the repo.
To build from the tarball do:
$ curl -O http://static.rust-lang.org/dist/rust-0.9.tar.gz $ tar -xzf rust-0.9.tar.gz $ cd rust-0.9Or to build from the repo do:
$ git clone https://github.com/mozilla/rust.git $ cd rustNow that you have Rust's source code, you can configure and build it:
$ ./configure $ make && make installNote: You may need to use
sudo make installif you do not normally have permission to modify the destination directory. The install locations can be adjusted by passing a--prefixargument toconfigure. Various other options are also supported, pass--helpfor more information on them.When complete,
make installwill place several programs into/usr/local/bin:rustc, the Rust compiler, andrustdoc, the API-documentation tool. system. -
Read the tutorial.
-
Enjoy!
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:
- Windows (7, 8, Server 2008 R2), x86 only
- Linux (2.6.18 or later, various distributions), x86 and x86-64
- OSX 10.7 (Lion) or greater, x86 and x86-64
You may find that other platforms work, but these are our officially supported build environments that are most likely to work.
Rust currently needs about 1.5 GiB of RAM to build without swapping; if it hits swap, it will take a very long time to build.
There is a lot more documentation in the wiki.
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.