Support multiline prompt in zsh

Notes:

- Unlike fish zsh outputs right prompt shifted by one to the left. Which means
  I have to subtract 1 from computed width.
- PS2 and PS3 produce too lengthy prompts when fed with real width. Thus they
  are fed with PS1 prompt width like in ipython (out prompts).

powerline/bindings/zsh/__init__.py

@@ -1,4 +1,6 @@
 # vim:fileencoding=utf-8:noet
+from __future__ import absolute_import, unicode_literals, division, print_function
+
 import zsh
 import atexit
 from powerline.shell import ShellPowerline
@@ -89,21 +91,22 @@ class ZshPowerline(ShellPowerline):
 	def precmd(self):
 		self.args.last_pipe_status = zsh.pipestatus()
 		self.args.last_exit_code = zsh.last_exit_code()
-		zsh.eval('_POWERLINE_PARSER_STATE="${(%):-%_}"')
 
 
 class Prompt(object):
-	__slots__ = ('powerline', 'side', 'savedpsvar', 'savedps', 'args', 'theme')
+	__slots__ = ('powerline', 'side', 'savedpsvar', 'savedps', 'args', 'theme', 'above')
 
-	def __init__(self, powerline, side, theme, savedpsvar=None, savedps=None):
+	def __init__(self, powerline, side, theme, savedpsvar=None, savedps=None, above=False):
 		self.powerline = powerline
 		self.side = side
+		self.above = above
 		self.savedpsvar = savedpsvar
 		self.savedps = savedps
 		self.args = powerline.args
 		self.theme = theme
 
 	def __str__(self):
+		zsh.eval('_POWERLINE_PARSER_STATE="${(%):-%_}"')
 		segment_info = {
 			'args': self.args,
 			'environ': environ,
@@ -111,7 +114,14 @@ class Prompt(object):
 			'local_theme': self.theme,
 			'parser_state': zsh.getvalue('_POWERLINE_PARSER_STATE'),
 		}
-		r = self.powerline.render(
+		r = ''
+		if self.above:
+			for line in self.powerline.render_above_lines(
+				width=zsh.columns() - 1,
+				segment_info=segment_info,
+			):
+				r += line + '\n'
+		r += self.powerline.render(
 			width=zsh.columns(),
 			side=self.side,
 			segment_info=segment_info,
@@ -131,13 +141,13 @@ class Prompt(object):
 			self.powerline.shutdown()
 
 
-def set_prompt(powerline, psvar, side, theme):
+def set_prompt(powerline, psvar, side, theme, above=False):
 	try:
 		savedps = zsh.getvalue(psvar)
 	except IndexError:
 		savedps = None
 	zpyvar = 'ZPYTHON_POWERLINE_' + psvar
-	prompt = Prompt(powerline, side, theme, psvar, savedps)
+	prompt = Prompt(powerline, side, theme, psvar, savedps, above)
 	zsh.set_special_string(zpyvar, prompt)
 	zsh.setvalue(psvar, '${' + zpyvar + '}')
 
@@ -146,7 +156,7 @@ def setup():
 	powerline = ZshPowerline(Args())
 	used_powerlines.append(powerline)
 	used_powerlines.append(powerline)
-	set_prompt(powerline, 'PS1', 'left', None)
+	set_prompt(powerline, 'PS1', 'left', None, above=True)
 	set_prompt(powerline, 'RPS1', 'right', None)
 	set_prompt(powerline, 'PS2', 'left', 'continuation')
 	set_prompt(powerline, 'RPS2', 'right', 'continuation')

powerline/bindings/zsh/powerline.zsh

@@ -111,21 +111,27 @@ _powerline_setup_prompt() {
 		fi
 	done
 	precmd_functions+=( _powerline_set_jobnum )
-	if zmodload libzpython &>/dev/null || zmodload zsh/zpython &>/dev/null ; then
+	if test -z "${POWERLINE_NO_ZSH_ZPYTHON}" && { zmodload libzpython || zmodload zsh/zpython } &>/dev/null ; then
 		precmd_functions+=( _powerline_update_counter )
 		zpython 'from powerline.bindings.zsh import setup as _powerline_setup'
 		zpython '_powerline = _powerline_setup()'
 		zpython 'del _powerline_setup'
 	else
-		local add_args='--last_exit_code=$? --last_pipe_status="$pipestatus"'
+		local add_args='--last_exit_code=$?'
+		add_args+=' --last_pipe_status="$pipestatus"'
 		add_args+=' --renderer_arg="client_id=$$"'
 		add_args+=' --jobnum=$_POWERLINE_JOBNUM'
-		local add_args_2=$add_args' -R parser_state=${(%%):-%_} -R local_theme=continuation'
+		local new_args_2=' -R parser_state=${(%%):-%_}'
-		PS1='$($POWERLINE_COMMAND shell left -r zsh_prompt '$add_args')'
+		new_args_2+=' -R local_theme=continuation'
+		local add_args_3=$add_args' -R local_theme=select'
+		local add_args_2=$add_args$new_args_2
+		add_args+=' --width=$(( COLUMNS - 1 ))'
+		local add_args_r2=$add_args$new_args_2
+		PS1='$($POWERLINE_COMMAND shell aboveleft -r zsh_prompt '$add_args')'
 		RPS1='$($POWERLINE_COMMAND shell right -r zsh_prompt '$add_args')'
 		PS2='$($POWERLINE_COMMAND shell left -r zsh_prompt '$add_args_2')'
-		RPS2='$($POWERLINE_COMMAND shell right -r zsh_prompt '$add_args_2')'
+		RPS2='$($POWERLINE_COMMAND shell right -r zsh_prompt '$add_args_r2')'
-		PS3='$($POWERLINE_COMMAND shell left -r zsh_prompt -R local_theme=select '$add_args')'
+		PS3='$($POWERLINE_COMMAND shell left -r zsh_prompt '$add_args_3')'
 	fi
 }