ress 0.1.0-patch

# RESS
> Rust EcmaScript Scanner

A scanner/tokenizer for JS written in Rust

## Usage
There are two interfaces for using `ress` in your Rust code.

The first is the very simple function `tokenize`, this takes in a `String` and outputs a `Vec<Token>`.

```rust
extern crate ress;

use ress::tokenize;

static &str JS = include_str!("index.js");

fn main() {
    let tokens = tokenize(JS);
    it !tokens.iter().any(|t| t.is_punct_with(";")) {
        panic!("No semi-colon!? You nave!");
    } else {
        println!("At least you are sane at one point");
    }
}

```

The other option is to create a `Scanner`, an iterator of tokens parsing them one by one from your js.
```rust
extern crate ress;

use ress::{Scanner};

static &str JS = include_str!("index.js");

fn main() {
    let s = Scanner::new(JS);
    for token in s {
        if token.is_punct_with(";") {
            panic!("A semi-colon!? Heathen!");
        }
    }
    println!("Good show! Why use something that's optional?")
}
```

In either method the major construct that you would be dealing with is a `Token` enum. This enum represents the 10 different tokens defined in the ECMAScript specification, plus `Comments`.

### ES Tokens
- Boolean Literal
- End of File
- Identifier
- Keyword
- Null Literal
- Numeric Literal
- Punctuation
- String Literal
- Regular Expression Literal
- Template
- Comment

In its current state it should be able to tokenize any valid <=ES6 JavaScript (I believe the testing is all currently done on ES3 packages though).

## Why?
Wouldn't it be nice to write new JS development tools in Rust? The (clear-comments)[./examples/clear-comments/src/main.rs] example is a proof of concept on how you might use this crate to do just that.

Ideally this project will be the starting point for building a full JS AST in Rust. The next step would be to build a companion crate that will raise the tokens into a full Abstract Syntax Tree. And once we have an AST a program that will write out JS text from that ast, essentially coming full circle.

# Performance
I am sure there are a lot of low hanging fruit in this area, on my 13" MBP Late 2013 2.4 GHz Intel Core i5
8 GB 1600 MHz DDR3 laptop running `cargo +nightly bench` provides the following info.

|Lib|Size|Time|+/-|
|---|---|---|---|
|Angular 1.5.6|1.16mb|2.81s|9.23ms|
|jquery|271.75kb|1.53s|61.42ms|
|React|59.09kb|0.23s|17.31ms|
|React-dom|641.51kb|2.47s|10.61ms|
|Vue|289.30kb|1.69s|4.98ms|

If you are interested in getting an idea about performance without waiting for `cargo bench` to complete you can run the following command.

```sh
$ cargo run --example major_libs
```