Simplify fullscreen to one function.

* basta.sh (badsta.fullscreen); Merges functionality of
basta.fullscreen_alt. When -s is not specified,
clears to end of screen, and calls
basta.ensure_bottom_margin. When calling this function,
we use the current value of $LINES rather than
recalculating realrows, removing one interaction to the
terminal. Since we are in full screen mode, we can
trust that $LINES is tracking the size.
When -s is specified, we don't clear to end of screen
or call basta.ensure_bottom_margin. Also we don't
need to provoke WINCH handling.
(basta.fullscreen_alt): Function removed.

* README.md: Documentation trimmed and revised.

2 files changed, 24 insertions, 79 deletions

diff --git a/README.md b/README.md
index 2ca61b4..83e808a 100644
--- a/README.md
+++ b/README.md
@@ -98,50 +98,23 @@ the full screen.
 Create `basta.fullscreen <program>` alias for each program that is to use
 the full terminal.
 
-The `basta.fullscreen` function works well with programs such as editors
-that use the full screen, and do not generate TTY-like output that scrolls the
-terminal. Some such programs save and restore the terminal screen.
-These work very well with `basta.fullscreen`.
-
-Programs that do not save and restore the terminal screen, or which generate
-some log messages before or after restoring the terminal screen, may cause a
-small cosmetic problem, like the Bash prompt appearing over top of a line of
-output from the program.  For the former category, full-screen programs
-which don't save and restore the terminal, one possible fix for the cosmetic
-issue is to use the `-s` (save and restore) option of `basta.fullscreen`,
-which saves and restores the terminal contents around the invocation of
-the program. For instance, many versions of the `top` utility are like this,
-and can be handled using:
+The `basta.fullscreen` function takes a single option, `-s`. If that
+is specified, then then Basta will save and restore the terminal around
+the invocation of the program. This should only be used for full-screen
+programs that don't output any messages outside of their full-screen paradigm,
+which should persist in the terminal window.
+
+The `top` utility is a good target for this. Some versions of `top` do not
+save and restore the screen, with with `basta.fullscreen -s top` we
+get that behavior:
 
    ::text
    alias top='basta.fullscreen -s top'
 
-Now the `top` command restores the terminal upon quitting.
-
-Programs which generate arbitrary scrolling output can be operated in full
-screen mode the function `basta.fullscreen_alt`. Almost any program, including
-non-interactive batch programs, can be run in full screen with this function.
-This function clears the screen and switches to the full scrolling area
-prior to running the program. Then when the program terminates, it checks
-the cursor position. The cursor position is assumed to be where the program
-produced its last line of output. The terminal is scrolled so that this
-last line of output is above the status area, which Basta then displays
-once again, and configures the scrolling region above it.
-
-Note for `git` users: though the `less` pager used by `git` normally saves
-and restores the terminal by default, `git` runs it in such a way that it does
-not do this: `git` adds some arguments to `less`.  To fix the behavior, add a
-`[core]` configuration section to  your `~/.gitconfig` file (if necessary) and
-then add the following `pager =` line to that section:
-
-    ::text
-    [core]  # add if necessary
-        pager = less -+Xn -+F
-
-Even with this setting, it is recommended to use `alias
-git='basta.fullscreen_alt git'` because `git` does not always use the pager;
-under some invocations, `git` behaves as noninteractive program
-which produces TTY-like scrolling output.
+Now the `top` command restores the terminal upon quitting. Note that
+with the above alias, it becomes impossible to see the output of `top -h` on
+the terminal; the terminal is quickly restored after `top -h` produces output,
+making it look as if no output had been produced.
 
 ## Environment
 
diff --git a/basta.sh b/basta.sh
index 4f6c032..1f4098c 100644
--- a/basta.sh
+++ b/basta.sh
@@ -312,15 +312,17 @@ basta.fullscreen() {
   fi
 
   local realrows=$(( LINES + basta_prev_reserved_rows + 1 ))
-  local exit=
+  local curline
+  local i
+  local exit=0
   local saveint=$(trap -p INT)
   local saveterm=
   local ttyfd
 
-  exec {ttyfd}<>/dev/tty
-
   trap : INT
 
+  exec {ttyfd}<>/dev/tty
+
   if [ "$1" == "-s" ] ; then
     shift
     saveterm=y
@@ -329,46 +331,16 @@ basta.fullscreen() {
 
   printf $'\e7\e[1;%sr\e8' $realrows >&$ttyfd
   stty rows $realrows <&$ttyfd
-  basta_deferred_intr=WINCH
-  LINES=$realrows command "$@"
-  exit=$?
-
-  [ $saveterm ] && printf $'\e[?1049l' >&$ttyfd
-
-  exec {ttyfd}>&-
-
-  eval "$saveint"
-
-  return $exit
-}
-
-basta.fullscreen_alt() {
-  if [ -n "$COMP_WORDS" ]; then
-    command "$@"
-    return $?
-  fi
-
-  local realrows=$(( LINES + basta_prev_reserved_rows + 1 ))
-  local curline
-  local i
-  local exit=0
-  local saveint=$(trap -p INT)
-  local ttyfd
-
-  trap : INT
-
-  exec {ttyfd}<>/dev/tty
-
-  printf $'\e7\e[1;%sr\e8' $realrows >&$ttyfd
-  stty rows $realrows <&$ttyfd
 
-  printf $'\e[J' >&$ttyfd
+  [ $saveterm ] || printf $'\e[J' >&$ttyfd && basta_deferred_intr=WINCH
 
-  basta_deferred_intr=WINCH
   LINES=$realrows command "$@" || exit=$?
 
-  basta.query_terminal_lines realrows >&$ttyfd <&$ttyfd &&
-    basta.ensure_bottom_margin $realrows >&$ttyfd
+  if [ $saveterm ] ; then
+    printf $'\e[?1049l' >&$ttyfd
+  else
+    basta.ensure_bottom_margin $LINES >&$ttyfd
+  fi
 
   exec {ttyfd}>&-