Skip to main content

A Java parser written in Python using PLY.

Project description

plyj [![Build Status](](

plyj is a Java parser written in Python. It has the awesome [PLY] as its sole dependency.


import plyj.parser as plyj

parser = plyj.Parser()

# parse a compilation unit from a file
tree = parser.parse_file(file('/foo/bar/'))

# parse a compilation unit from a string
tree = parser.parse_string('class Foo { }')

# parse expression from string
tree = parser.parse_expression('1 / 2 * (float) 3')

# slightly bigger example: parse from an installed JDK with sources
import zipfile
srczip = zipfile.ZipFile('/usr/lib/jvm/java-6-openjdk/', mode='r')
info = srczip.getinfo('java/lang/')
srcfile =
tree = parser.parse_file(srcfile)


plyj is more or less a 1:1 translation of the grammar used in the [Java Development Tools] for Eclipse.


The grammar is complete. There may still be errors left though. It successfully parsed every source file of the Oracle JDK. A lot of bugs were found that way but for all I know there may be many more. Time will tell.


Contributions are always welcome. Depending on the type of work it may
take a little while until I get around to accepting them.

* commit test that demonstrates a bug (optional)
* commit the fix
* open pull request

The test is required but does *not* have to be provided by you. If you
do provide it, committing it first shows appropriate messages in the
pull request and makes it easier to accept via Web.


A word of caution: Since plyj is pure Python, it is quite slow. Based on my laptop (which has an i7-3517U @ 1.90 GHz) I can present the following numbers (running inside a virtual machine):

* 619 rules
* 1149 states
* ~3.28 seconds to compile the grammar
* java/util/ takes ~0.44 seconds to parse (it's quite big though)

The timings are obviously highly dependent on the used hardware. My old laptop (Core 2 Duo @ 1 GHz) took 17 and 1.8 seconds respectively.

[Java Development Tools]:

Project details

Release history Release notifications | RSS feed

This version


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for plyj, version 0.1
Filename, size File type Python version Upload date Hashes
Filename, size plyj-0.1.tar.gz (18.4 kB) File type Source Python version None Upload date Hashes View

Supported by

Pingdom Pingdom Monitoring Google Google Object Storage and Download Analytics Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN DigiCert DigiCert EV certificate StatusPage StatusPage Status page