Refactor command argument splitting.

This uses split=True/False as cmdutils.register argument again (because
we would never want to set maxsplit ourselves, only not splitting the
*last* argument makes any sense.

Also this uses shlex for splitting again, like earlier.

TODO

@@ -40,7 +40,6 @@ Ctrl+A/X to increase/decrease last number in URL
 command completion gets hidden when doing a new ValueList value
 logging contexts
 catch import errors for PyQt and QtWebKit
-How do we handle empty values in input bar?
 - Add more element-selection-detection code (with options?) based on:
       -> javascript: http://stackoverflow.com/a/2848120/2085149
       -> microFocusChanged and check active element via:

qutebrowser/app.py

@@ -420,7 +420,7 @@ class QuteBrowser(QApplication):
             logging.debug("maybe_quit quitting.")
             self.quit()
 
-    @cmdutils.register(instance='', maxsplit=0)
+    @cmdutils.register(instance='', split=False)
     def pyeval(self, s):
         """Evaluate a python string and display the results as a webpage.
 

qutebrowser/browser/curcommand.py

@@ -86,7 +86,8 @@ class CurCommandDispatcher(QObject):
             return
         widget.hintmanager.follow_prevnext(frame, widget.url(), prev, newtab)
 
-    @cmdutils.register(instance='mainwindow.tabs.cur', name='open', maxsplit=0)
+    @cmdutils.register(instance='mainwindow.tabs.cur', name='open',
+                       split=False)
     def openurl(self, url, count=None):
         """Open an url in the current/[count]th tab.
 

qutebrowser/commands/_command.py

@@ -32,10 +32,7 @@ class Command(QObject):
 
     Attributes:
         name: The main name of the command.
-        maxsplit: Maximum count of splits to be made.
-            -1: Split everything (default)
-            0:  Don't split.
-            n:  Split a maximum of n times.
+        split: Whether to split the arguments.
         hide: Whether to hide the arguments or not.
         nargs: A (minargs, maxargs) tuple, maxargs = None if there's no limit.
         count: Whether the command supports a count, or not.
@@ -57,13 +54,13 @@ class Command(QObject):
 
     signal = pyqtSignal(tuple)
 
-    def __init__(self, name, maxsplit, hide, nargs, count, desc, instance,
+    def __init__(self, name, split, hide, nargs, count, desc, instance,
                  handler, completion, modes, not_modes, needs_js):
         # I really don't know how to solve this in a better way, I tried.
         # pylint: disable=too-many-arguments
         super().__init__()
         self.name = name
-        self.maxsplit = maxsplit
+        self.split = split
         self.hide = hide
         self.nargs = nargs
         self.count = count

qutebrowser/commands/managers.py

@@ -26,6 +26,7 @@ import qutebrowser.config.config as config
 import qutebrowser.commands.utils as cmdutils
 import qutebrowser.utils.message as message
 from qutebrowser.commands._exceptions import NoSuchCommandError, CommandError
+from qutebrowser.utils.misc import safe_shlex_split
 
 
 def split_cmdline(text):
@@ -168,15 +169,15 @@ class CommandManager:
 
         if len(parts) == 1:
             args = []
+        elif cmd.split:
+            args = safe_shlex_split(parts[1])
         else:
-            logging.debug("Splitting '{}' with max {} splits".format(
-                parts[1], cmd.maxsplit))
-            args = parts[1].split(maxsplit=cmd.maxsplit)
+            args = parts[1].split(maxsplit=cmd.nargs[0] - 1)
         self._cmd = cmd
         self._args = args
         retargs = args[:]
-        if text.endswith(' ') and (cmd.maxsplit == -1 or
-                                   len(args) <= cmd.maxsplit):
+        if text.endswith(' ') and (cmd.split is True or
+                                   len(args) < cmd.args[0]):
             retargs.append('')
         return [cmdstr] + retargs
 

qutebrowser/commands/utils.py

@@ -40,10 +40,7 @@ class register:  # pylint: disable=invalid-name
         instance: The instance to be used as "self", as a dotted string.
         name: The name (as string) or names (as list) of the command.
         nargs: A (minargs, maxargs) tuple of valid argument counts, or an int.
-        maxsplit: Maximum count of splits to be made.
-            -1: Split everything (default)
-            0:  Don't split.
-            n:  Split a maximum of n times.
+        split: Whether to split the arguments.
         hide: Whether to hide the command or not.
         completion: Which completion to use for arguments, as a list of
                     strings.
@@ -51,7 +48,7 @@ class register:  # pylint: disable=invalid-name
         needs_js: If javascript is needed for this command.
     """
 
-    def __init__(self, instance=None, name=None, nargs=None, maxsplit=-1,
+    def __init__(self, instance=None, name=None, nargs=None, split=True,
                  hide=False, completion=None, modes=None, not_modes=None,
                  needs_js=False):
         """Save decorator arguments.
@@ -64,7 +61,7 @@ class register:  # pylint: disable=invalid-name
         if modes is not None and not_modes is not None:
             raise ValueError("Only modes or not_modes can be given!")
         self.name = name
-        self.maxsplit = maxsplit
+        self.split = split
         self.hide = hide
         self.nargs = nargs
         self.instance = instance
@@ -105,7 +102,7 @@ class register:  # pylint: disable=invalid-name
             desc = func.__doc__.splitlines()[0].strip().rstrip('.')
         else:
             desc = ""
-        cmd = Command(name=mainname, maxsplit=self.maxsplit,
+        cmd = Command(name=mainname, split=self.split,
                       hide=self.hide, nargs=nargs, count=count, desc=desc,
                       instance=self.instance, handler=func,
                       completion=self.completion, modes=self.modes,

qutebrowser/config/config.py

@@ -310,7 +310,7 @@ class ConfigManager(QObject):
             newval = val.typ.transform(newval)
         return newval
 
-    @cmdutils.register(name='set', instance='config', maxsplit=2,
+    @cmdutils.register(name='set', instance='config',
                        completion=['section', 'option', 'value'])
     def set_wrapper(self, section, option, value):
         """Set an option.
@@ -322,7 +322,7 @@ class ConfigManager(QObject):
         except (NoOptionError, NoSectionError, ValidationError) as e:
             message.error("set: {} - {}".format(e.__class__.__name__, e))
 
-    @cmdutils.register(name='set_temp', instance='config', maxsplit=2,
+    @cmdutils.register(name='set_temp', instance='config',
                        completion=['section', 'option', 'value'])
     def set_temp_wrapper(self, section, option, value):
         """Set a temporary option.

qutebrowser/utils/misc.py

@@ -17,6 +17,7 @@
 
 """Other utilities which don't fit anywhere else."""
 
+import shlex
 from functools import reduce
 from pkg_resources import resource_string
 
@@ -46,3 +47,32 @@ def dotted_getattr(obj, path):
         The object at path.
     """
     return reduce(getattr, path.split('.'), obj)
+
+
+def safe_shlex_split(s):
+    r"""Split a string via shlex safely (don't bail out on unbalanced quotes).
+
+    We split while the user is typing (for completion), and as
+    soon as " or \ is typed, the string is invalid for shlex,
+    because it encounters EOF while in quote/escape state.
+
+    Here we fix this error temporarely so shlex doesn't blow up,
+    and then retry splitting again.
+
+    Since shlex raises ValueError in both cases we unfortunately
+    have to parse the exception string...
+    """
+    try:
+        return shlex.split(s)
+    except ValueError as e:
+        if str(e) == "No closing quotation":
+            # e.g.   eggs "bacon ham
+            # -> we fix this as   eggs "bacon ham"
+            s += '"'
+        elif str(e) == "No escaped character":
+            # e.g.   eggs\
+            # -> we fix this as  eggs\\
+            s += '\\'
+        else:
+            raise
+        return shlex.split(s)

qutebrowser/widgets/_tabbedbrowser.py

@@ -222,12 +222,12 @@ class TabbedBrowser(TabWidget):
         elif last_close == 'blank':
             tab.openurl('about:blank')
 
-    @cmdutils.register(instance='mainwindow.tabs', maxsplit=0)
+    @cmdutils.register(instance='mainwindow.tabs', split=False)
     def tabopen(self, url):
         """Open a new tab with a given url."""
         self._tabopen(url, background=False)
 
-    @cmdutils.register(instance='mainwindow.tabs', maxsplit=0)
+    @cmdutils.register(instance='mainwindow.tabs', split=False)
     def backtabopen(self, url):
         """Open a new tab in background."""
         self._tabopen(url, background=True)