Improved support for leading newline

* New modes that either print it only when it isn't the first line, or
    only add it (as well as a warning) if the last command didn't return
    a newline.
  * Overengineered af.

README.md

@@ -142,8 +142,16 @@ The `layout_*` variables control the prompt's layout and general appearance:
   default this entry contains an empty string.
 * `layout_input_always` determines whether the input line should be rendered
   even if no generators are specified (`0` or `1`, default `0`).
-* `layout_empty_line` prints an empty line before the prompt's top line. This
-  prevents display problems when some command outputs a line without `\n`.
+* `layout_empty_line` determines how the prompt handles printing an empty line
+  before the prompt's top line.
+  * When set to `0`, no extra line is drawn, and commands that do not end with
+    an EOL will cause the prompt's first line to be displayed incorrectly.
+  * When set to `1`, the prompt's top line will always be preceeded with an
+    empty line.
+  * When set to `2`, the prompt will be preceeded by an empty line unless it
+    is being drawn on the terminal's first line.
+  * When set to `3`, a newline will be added to the prompt if the last
+    command's output didn't end with a newline.
 
 The `term_*` variables control the prompt's ability to change the terminal's
 title and/or icon title:

example-gprompt.rc

@@ -33,8 +33,9 @@
 	] ,
 	# - Always generate input line?
 	layout_input_always => 0 ,
-	# - Add an empty line before the prompt?
-	layout_empty_line => 0 ,
+	# - Add an empty line before the prompt? 0=no, 1=always, 2=not at the top
+	# of the terminal, 3=only if the previous command didn't finish with \n
+	layout_empty_line => 3 ,
 
 	# TERMINAL TITLE
 	# - Set title from the prompt? 0=no, 1=normal, 2=minimized, 3=both

gprompt.pl

@@ -12,7 +12,7 @@ use strict;
 use warnings;
 use utf8;
 use open ':std', ':encoding(UTF-8)';
-use POSIX qw(strftime);
+use POSIX qw(strftime :termios_h);
 use Cwd qw(abs_path getcwd);
 
 
@@ -45,8 +45,9 @@ our %CONFIG = (
 	layout_input => [ qw( userhost cwd ) ] ,
 	# - Always generate input line?
 	layout_input_always => 0 ,
-	# - Add an empty line before the prompt?
-	layout_empty_line => 0 ,
+	# - Add an empty line before the prompt? 0=no, 1=always, 2=not at the top
+	# of the terminal, 3=only if the previous command didn't finish with \n
+	layout_empty_line => 3 ,
 
 	# TERMINAL TITLE
 	# - Set title from the prompt? 0=no, 1=normal, 2=minimized, 3=both
@@ -151,6 +152,13 @@ sub default_theme
 		'bg_ps2' => -2,
 		ps2_suffix => ' : ' ,
 
+		# Text appended to a line without EOL when layout_empty_line is 3
+		'noeol_text' => '<NO EOL>' ,
+		# Colors and style for the above text
+		'noeol_fg' => 1 ,
+		'noeol_bg' => -1 ,
+		'noeol_style' => 'b' ,
+
 		# Current working directory - Truncation string
 		cwd_trunc => '...' ,
 		# Current working directory - Foreground / background colors
@@ -302,6 +310,51 @@ sub set_color
 	return tput_sequence( "seta$type $index" );
 }
 
+sub get_cursor_pos
+{
+	local $| = 1;
+	open(my $ttyIn, '<:bytes' , '/dev/tty');
+	open(my $ttyOut, '>:bytes' , '/dev/tty');
+
+	# Enable raw mode
+	my $term = POSIX::Termios->new;
+	my $ttyInFd = fileno $ttyIn;
+	$term->getattr($ttyInFd);
+	my $oTerm = $term ->getlflag;
+	$term->setlflag($oTerm & ~( ECHO | ECHOK | ICANON ));
+	$term->setcc(VTIME, 1);
+	$term->setattr($ttyInFd, TCSANOW);
+
+	# Read position
+	syswrite $ttyOut, "\033[6n", 4;
+	my ($input, $col, $line) = ("", "", "");
+	my $state = 0;
+	while (sysread $ttyIn, $input, 1) {
+		if ($state == 0) {
+			$state = 1 if $input eq '[';
+		} elsif ($state == 1) {
+			if ($input eq ';') {
+				$state = 2;
+			} else {
+				$line .= $input;
+			}
+		} elsif ($state == 2) {
+			last if $input eq 'R';
+			$col .= $input;
+		}
+	}
+
+	# Enable cooked mode
+	$term->setlflag($oTerm);
+	$term->setcc(VTIME, 0);
+	$term->setattr($ttyInFd, TCSANOW);
+
+	close $ttyIn;
+	close $ttyOut;
+
+	return $line, $col;
+}
+
 #}}}
 # Theming support -----------------------------------------------------------{{{
 
@@ -593,6 +646,33 @@ sub render
 #}}}
 # Prompt parts --------------------------------------------------------------{{{
 
+sub gen_empty_line
+{
+	my $lel = $CONFIG{layout_empty_line};
+	my $nl;
+	my $out = "";
+	if ($lel > 1) {
+		my ($line, $col) = get_cursor_pos;
+		$nl = ( $lel == 2 && $line != 1 ) || ( $lel == 3 && $col != 1 );
+		if ( $lel == 3 && $col != 1 ) {
+			$out .= render('input', {
+				content => [
+					{
+						style => themed 'noeol_style' ,
+						fg => themed 'noeol_fg' ,
+						bg => themed 'noeol_bg' ,
+					},
+					( themed 'noeol_text' )
+				]
+			});
+		}
+	} else {
+		$nl = $lel
+	}
+	$out .= "\\n" if $nl;
+	return $out;
+}
+
 sub gen_top_line
 {
 	my @left = @{ $CONFIG{layout_left} };
@@ -750,17 +830,24 @@ _gprompt_set_return() {
 	return "\${1:-0}"
 }
 gprompt_command() {
-	local cmd_status=\$?
+	_GPROMPT_PREV_STATUS=\$?
 	local jobs=(\$(jobs -p))
 	eval "\$_GPROMPT_PREVIOUS_PCMD"
-	eval "\$( perl \Q$gpPath\E "rc:\$cmd_status" "jobs:\${#jobs[@]}" )"
-	_gprompt_set_return "\$cmd_status"
+	eval "\$( perl \Q$gpPath\E "rc:\$_GPROMPT_PREV_STATUS" "jobs:\${#jobs[@]}" )"
+	_gprompt_set_return "\$_GPROMPT_PREV_STATUS"
+}
+_gprompt_clear() {
+	clear -x
+	_gprompt_set_return "\${_GPROMPT_PREV_STATUS:-0}"
+	gprompt_command
+	echo -n "\${PS1\@P}\r"
 }
 shopt -s checkwinsize
 if [[ \$PROMPT_COMMAND != *"gprompt_command"* ]]; then
 	_GPROMPT_PREVIOUS_PCMD="\$PROMPT_COMMAND"
 	PROMPT_COMMAND="gprompt_command"
 fi
+bind -x \$'"\\C-l":_gprompt_clear'
 EOF
 	exit 0;
 }
@@ -793,7 +880,7 @@ sub main
 	%TLEN = compute_trans_lengths;
 	my $pg = gen_term_title;
 	my $ps1 = $pg;
-	$ps1 .= "\\n" if $CONFIG{layout_empty_line};
+	$ps1 .= gen_empty_line;
 	$ps1 .= gen_top_line;
 	my ( $ill , $ilt ) = gen_input_line;
 	$ps1 .= $ilt;

themes/ascii_gyr.pm

@@ -42,6 +42,13 @@
 	'bg_ps2' => thref 'bg',
 	ps2_suffix => '\b2\f3| ' ,
 
+	# Text appended to a line without EOL when layout_empty_line is 3
+	'noeol_text' => '<NO EOL>' ,
+	# Colors and style for the above text
+	'noeol_fg' => thref 'fg3' ,
+	'noeol_bg' => thref 'bg3' ,
+	'noeol_style' => 'b' ,
+
 	# Current working directory - Truncation string
 	cwd_trunc => '...' ,
 	# Current working directory - Foreground / background colors

themes/ascii_yb.pm

@@ -42,6 +42,13 @@
 	'bg_ps2' => thref 'bg',
 	ps2_suffix => '\b2\f3| ' ,
 
+	# Text appended to a line without EOL when layout_empty_line is 3
+	'noeol_text' => '<NO EOL>' ,
+	# Colors and style for the above text
+	'noeol_fg' => thref 'fg3' ,
+	'noeol_bg' => thref 'bg3' ,
+	'noeol_style' => 'b' ,
+
 	# Current working directory - Truncation string
 	cwd_trunc => '...' ,
 	# Current working directory - Foreground / background colors

themes/blocks_gyr.pm

@@ -42,6 +42,13 @@
 	'bg_ps2' => thref 'bg',
 	'ps2_suffix' => "\\b2\\f3\x{250a} ",
 
+	# Text appended to a line without EOL when layout_empty_line is 3
+	'noeol_text' => "\x{b6}" ,
+	# Colors and style for the above text
+	'noeol_fg' => thref 'fg3' ,
+	'noeol_bg' => thref 'bg3' ,
+	'noeol_style' => 'b' ,
+
 	# Current working directory - Truncation string
 	'cwd_trunc' => "\x{2026}",
 	# Current working directory - Foreground / background colors

themes/blocks_yb.pm

@@ -42,6 +42,13 @@
 	'bg_ps2' => thref 'bg',
 	'ps2_suffix' => "\\b2\\f3\x{250a} ",
 
+	# Text appended to a line without EOL when layout_empty_line is 3
+	'noeol_text' => "\x{b6}" ,
+	# Colors and style for the above text
+	'noeol_fg' => thref 'fg3' ,
+	'noeol_bg' => thref 'bg3' ,
+	'noeol_style' => 'b' ,
+
 	# Current working directory - Truncation string
 	'cwd_trunc' => "\x{2026}",
 	# Current working directory - Foreground / background colors

themes/powerline_gyr.pm

@@ -41,6 +41,13 @@
 	'bg_ps2' => 234,
 	'ps2_suffix' => '\f0\b2'."\x{e0b0}".'\f2\b1'."\x{e0b0}".' ' ,
 
+	# Text appended to a line without EOL when layout_empty_line is 3
+	'noeol_text' => "\x{e0b0} \x{26a0} \x{e0b2}" ,
+	# Colors and style for the above text
+	'noeol_fg' => thref 'fg3' ,
+	'noeol_bg' => thref 'bg3' ,
+	'noeol_style' => 'b' ,
+
 	# Current working directory - Truncation string
 	'cwd_trunc' => "\x{2026}",
 	# Current working directory - Foreground / background colors

themes/powerline_yb.pm

@@ -41,6 +41,13 @@
 	'bg_ps2' => 234,
 	'ps2_suffix' => '\f0\b2'."\x{e0b0}".'\f2\b1'."\x{e0b0}".' ' ,
 
+	# Text appended to a line without EOL when layout_empty_line is 3
+	'noeol_text' => "\x{e0b0} \x{26a0} \x{e0b2}" ,
+	# Colors and style for the above text
+	'noeol_fg' => thref 'fg3' ,
+	'noeol_bg' => thref 'bg3' ,
+	'noeol_style' => 'b' ,
+
 	# Current working directory - Truncation string
 	'cwd_trunc' => "\x{2026}",
 	# Current working directory - Foreground / background colors