Adds an IPython kernel running in NaCl, and a wrapper as a Chrome extension.

ports/ipython-ppapi/kernel.py

Index: ports/ipython-ppapi/kernel.py
diff --git a/ports/ipython-ppapi/kernel.py b/ports/ipython-ppapi/kernel.py
new file mode 100755
index 0000000000000000000000000000000000000000..ffa057ea9a6061a134e20da5b7697d19d255a13d
--- /dev/null
+++ b/ports/ipython-ppapi/kernel.py
@@ -0,0 +1,249 @@
+# Copyright (c) 2014 Google Inc. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""A simple shell that uses the IPython messaging system."""
+
+import json
+import logging
+import sys
+
+import IPython
+from IPython.core.interactiveshell import InteractiveShell, InteractiveShellABC
+from IPython.utils.traitlets import Type, Dict, Instance
+from IPython.core.displayhook import DisplayHook
+from IPython.utils.jsonutil import json_clean, encode_images
+from IPython.core.displaypub import DisplayPublisher
+from IPython.config.configurable import Configurable
+
+# module defined in shell.cc for communicating via pepper API
+import ppmessage
+
+def sendMessage(socket_name, msg_type, parent_header=None, content=None):
+  if parent_header is None:
+    parent_header = {}
+  if content is None:
+    content = {}
+  msg = {
+      'header': {'msg_type': msg_type},
+      'parent_header': parent_header,
+      'content': content
+      }
+  ppmessage._PostJSONMessage(socket_name, json.dumps(msg))
+
+class MsgOutStream(object):
+  """Class to overrides stderr and stdout."""
+
+  def __init__(self, stream_name):
+    self._stream_name = stream_name
+    self._parent_header = {}
+
+  def SetParentHeader(self, parent_header):
+    self._parent_header = parent_header
+
+  def close(self):
+    pass
+
+  def flush(self):
+    pass
+
+  def write(self, string):
+    sendMessage('iopub', 'stream', parent_header=self._parent_header,
+                content={'name': self._stream_name, 'data': string})
+
+  def writelines(self, sequence):
+    for string in sequence:
+      self.write(string)
+
+# override sys.stdout and sys.stderr to broadcast on iopub
+stdout_stream = MsgOutStream('stdout')
+stderr_stream = MsgOutStream('stderr')
+sys_stdout = sys.stdout
+sys_stderr = sys.stderr
+sys.stdout = stdout_stream
+sys.stderr = stderr_stream
+
+
+
+class PepperShellDisplayHook(DisplayHook):
+  parent_header = Dict({})
+
+  def set_parent_header(self, parent_header):
+    """Set the parent for outbound messages."""
+    self.parent_header = parent_header
+
+  def start_displayhook(self):
+    self.content = {}
+
+  def write_output_prompt(self):
+    self.content['execution_count'] = self.prompt_count
+
+  def write_format_data(self, format_dict, md_dict=None):
+    self.content['data'] = encode_images(format_dict)
+    self.content['metadata'] = md_dict
+
+  def finish_displayhook(self):
+    sys.stdout.flush()
+    sys.stderr.flush()
+    sendMessage('iopub', 'pyout', parent_header=self.parent_header,
+                content=self.content)
+    self.content = None
+
+
+class PepperDisplayPublisher(DisplayPublisher):
+  parent_header = Dict({})
+
+  def set_parent_header(self, parent_header):
+    self.parent_header = parent_header
+
+  def _flush_streams(self):
+    """flush IO Streams prior to display"""
+    sys.stdout.flush()
+    sys.stderr.flush()
+
+  def publish(self, source, data, metadata=None):
+    self._flush_streams()
+    if metadata is None:
+      metadata = {}
+    self._validate_data(source, data, metadata)
+    content = {}
+    content['source'] = source
+    content['data'] = encode_images(data)
+    content['metadata'] = metadata
+    sendMessage('iopub', 'display_data', content=json_clean(content),
+                parent_header=self.parent_header)
+
+  def clear_output(self, stdout=True, stderr=True, other=True):
+    content = dict(stdout=stdout, stderr=stderr, other=other)
+
+    if stdout:
+      sys.stdout.write('\r')
+    if stderr:
+      sys.stderr.write('\r')
+
+    self._flush_streams()
+    sendMessage('iopub', 'clear_output', content=content,
+                parent_header=self.parent_header)
+
+
+class PepperInteractiveShell(InteractiveShell):
+    """A subclass of InteractiveShell for the Pepper Messagin API."""
+    displayhook_class = Type(PepperShellDisplayHook)
+    display_pub_class = Type(PepperDisplayPublisher)
+    @staticmethod
+    def enable_gui(gui):
+        pass
+
+
+InteractiveShellABC.register(PepperInteractiveShell)
+
+class PepperKernel(Configurable):
+    shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
+    shell_class = Type(PepperInteractiveShell)
+
+    def __init__(self):
+        self.shell = self.shell_class.instance(parent=self)
+        self.shell.run_cell("""
+import os
+matplotlib_config_dir = '/mplconfigdir'
+os.environ['XDG_CONFIG_HOME'] = matplotlib_config_dir
+os.environ['TMP'] = ''
+import matplotlib
+import matplotlib.cbook
+""")
+
+execution_count = 1
+
+shell = PepperKernel().shell
+
+# Special message to indicate the NaCl kernel is ready.
+sendMessage('iopub', 'status', content={'execution_state': 'nacl_ready'})
+
+while 1:
+  sendMessage('iopub', 'status', content={'execution_state': 'idle'})
+  msg = json.loads(ppmessage._AcquireJSONMessageWait())
+  sendMessage('iopub', 'status', content={'execution_state': 'busy'})
+
+  if not 'header' in msg:
+    continue
+  request_header = msg['header']
+  if not 'msg_type' in request_header:
+    continue
+  msg_type = request_header['msg_type']
+  if msg_type == 'execute_request':
+    try:
+      content = msg[u'content']
+      code = content[u'code']
+      silent = content[u'silent']
+      store_history = content.get(u'store_history', not silent)
+    except:
+      self.log.error("Got bad msg: ")
+      self.log.error("%s", msg)
+      continue
+
+    # Let output streams know which message the output is for
+    stdout_stream.SetParentHeader(request_header)
+    stderr_stream.SetParentHeader(request_header)
+    shell.displayhook.set_parent_header(request_header)
+    shell.display_pub.set_parent_header(request_header)
+
+    status = 'ok'
+    content = {}
+    try:
+      shell.run_cell(msg['content']['code'],
+                     store_history=store_history,
+                     silent=silent)
+    except Exception, ex:
+      status = 'error'
+      logging.exception('Exception occured while running cell')
+
+    content = {'status': status,
+             'execution_count': execution_count}
+
+    if status == 'ok':
+      content['payload'] = []
+      content['user_variables'] = {}
+      content['user_expressions'] = {}
+    elif status == 'error':
+      content['ename'] = type(ex).__name__
+      content['evalue'] = str(ex)
+      content['traceback'] = []
+
+    execution_count += 1
+    if status == 'error':
+      sendMessage('iopub', 'pyerr', parent_header=request_header,
+                  content={
+                      'execution_count': execution_count,
+                      'ename': type(ex).__name__,
+                      'evalue': str(ex),
+                      'traceback': []
+                      }
+                  )
+    sendMessage('shell', 'execute_reply', parent_header=request_header,
+                content=content)
+  elif msg_type == 'complete_request':
+    c = msg['content']
+    try:
+      cpos = int(c['cursor_pos'])
+    except:
+      cpos = len(c['text'])
+      if cpos == 0:
+        cpos = len(c['line'])
+    txt, matches = shell.complete(c['text'], c['line'], cpos)
+    sendMessage('shell', 'complete_reply',
+                parent_header = request_header,
+                content = {
+                    'matches': matches,
+                    'matched_text': txt,
+                    'status': 'ok'
+                    })
+  elif msg_type == 'restart':
+    # break out of this loop, ending this program.
+    # The main event loop in shell.cc will then
+    # run this program again.
+    break
+  elif msg_type == 'kill':
+    # Raise an exception so that the function
+    # running this script will return -1, resulting
+    # in no restart of this script.
+    raise RuntimeError