Add entrypoint for command line usage

README.rst

@@ -32,6 +32,13 @@ If you are lazy, "str2json" will apply the "parse" method of ast on a string for
 
     >>> str2json(open('some_python_source_file.py').read())
 
+You can also run via the command line to parse Python source from stdin and print to stdout:
+
+::
+
+    $ ast2json < some_python_source_file.py
+
+
 Example
 =======
 

ast2json/ast2json.py

@@ -23,6 +23,7 @@
 # ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+import sys
 from _ast import AST
 from ast import parse
 from .types import BUILTIN_PURE, BUILTIN_STR, BUILTIN_BYTES
@@ -65,6 +66,10 @@ def get_value(attr_value):
         raise Exception("unknown case for '%s' of type '%s'" % (attr_value, type(attr_value)))
 
 
+def main(stream=sys.stdin):
+    print(json.dumps(ast2json(parse(stream.read())), indent=4))
+
+
 if __name__ == '__main__':
-    import json
-    print(json.dumps(ast2json(parse(open(__file__, "r").read())), indent=4))
+    with open(__file__, "r") as f:
+        main(f)

setup.py

@@ -22,6 +22,11 @@
       keywords='ast',
       packages=find_packages(),
       install_requires=[],
+      entry_points={
+          'console_scripts': [
+              'ast2json = ast2json.ast2json:main',
+          ]
+      },
       # See https://pypi.python.org/pypi?%3Aaction=list_classifiers
       classifiers=[
                    # How mature is this project? Common values are