https://github.com/calvin-l/gen2it

Compiles python-style generators to java-style iterators
https://github.com/calvin-l/gen2it

Last synced: 2 months ago
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Compiles python-style generators to java-style iterators

• Host: GitHub
• URL: https://github.com/calvin-l/gen2it
• Owner: Calvin-L
• Created: 2017-01-31T20:48:22.000Z (almost 8 years ago)
• Default Branch: master
• Last Pushed: 2017-02-02T19:40:52.000Z (almost 8 years ago)
• Last Synced: 2024-04-23T02:10:45.401Z (8 months ago)
• Language: Python
• Size: 17.6 KB
• Stars: 6
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Generator to Iterator Converter

This tool compiles generator methods to Java-style iterators.

Generator methods are a very convenient way to write code that produces streams

of values: they are normal functions that periodically yield values to the

caller. In many cases it is easier to express a stream of values as a generator

than to manually write an implementation of

[Iterator](https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html).

For example, a generator method to produce Fibonacci numbers might look like

this:

```

int a = 1;

int b = 1;

while (true) {

    yield(a);     // produce a value

    int prev_a = a;

    a = b;

    b += prev_a;

}

```

## Using the tool

I expect you to be running Python 3. Install dependencies with `pip`:

    $ pip3 install -r requirements.txt

Invoke the tool by running:

    $ python3 -m gen2it INPUT_FILE -o OUTPUT_FILE

The input should be a Java source file with a single class having a

`TypeName generate(args...)` method. That method may call

`yield(TypeName value)` to yield

values. The output is a Java source file with `boolean hasNext()` and

`TypeName next()` methods.

Sample inputs for the tool can be found in the examples folder.

## Usage Notes

 - The generated iterators are not threadsafe. You will need to manually

   synchronize calls to any method on the generated iterator classes.

 - This style of programming can be [faked in pure Java using threads](https://github.com/mherrmann/java-generator-functions),

   however, this tool will avoid the overhead of the extra threads and the risks

   of leaking memory through them.

 - Many features are not yet implemented. Feel free to file issues or open pull

   requests to fix missing functionality. A few things that may not work

   properly yet:

    - try-catch and try-with-resources

    - for-loops

    - using a for-each loop over an array