fix(bash/preexec): support termcap names for tput (#1670)

* fix(bash/preexec): support termcap-based tput

The current uses of tput specify the terminfo entry names.  However,
there are different implementations of the tput command.  There are
two ways to specify the terminal capability: terminfo and termcap
names.  Although recent implementations of tput (such as ncurses in
Linux) accepts the terminfo name, some accept both the terminfo and
termcap names, and some old implementations (such as in FreeBSD) only
accept the termcap names.

In this patch, we first attempt the terminfo name and then the termcap
name if the terminfo name fails.

Note: When both fail due to e.g. non-existent tput, we end up with
outputting nothing.  This does not cause a serious problem because it
just does not clear the previous prompts.

* perf(bash/preexec): cache the results of tput

With the current implementation, we spwan 10 processes of the tput
command at most every time we perform `enter_accept`.  In this patch,
to reduce the delay, we separate the related code into a function and
cache the results of the tput commands.

1 files changed, 25 insertions, 11 deletions

diff --git a/atuin/src/shell/atuin.bash b/atuin/src/shell/atuin.bash
index c632cf9d..e40e8c56 100644
--- a/atuin/src/shell/atuin.bash
+++ b/atuin/src/shell/atuin.bash
@@ -100,22 +100,35 @@ else
     }
 fi
 
+# The shell function `__atuin_clear_prompt N` outputs terminal control
+# sequences to clear the contents of the current and N previous lines.  After
+# clearing, the cursor is placed at the beginning of the N-th previous line.
+__atuin_clear_prompt_cache=()
+__atuin_clear_prompt() {
+    local offset=$1
+    if [[ ! ${__atuin_clear_prompt_cache[offset]+set} ]]; then
+        if [[ ! ${__atuin_clear_prompt_cache[0]+set} ]]; then
+            __atuin_clear_prompt_cache[0]=$'\r'$(tput el 2>/dev/null || tput ce 2>/dev/null)
+        fi
+        if ((offset > 0)); then
+            __atuin_clear_prompt_cache[offset]=${__atuin_clear_prompt_cache[0]}$(
+                tput cuu "$offset" 2>/dev/null || tput UP "$offset" 2>/dev/null
+                tput dl "$offset"  2>/dev/null || tput DL "$offset" 2>/dev/null
+                tput il "$offset"  2>/dev/null || tput AL "$offset" 2>/dev/null
+            )
+        fi
+    fi
+    printf '%s' "${__atuin_clear_prompt_cache[offset]}"
+}
+
 __atuin_accept_line() {
     local __atuin_command=$1
 
     # Reprint the prompt, accounting for multiple lines
     local __atuin_prompt __atuin_prompt_offset
     __atuin_evaluate_prompt
-    local __atuin_clear_prompt
-    __atuin_clear_prompt=$'\r'$(tput el)
-    if ((__atuin_prompt_offset > 0)); then
-        __atuin_clear_prompt+=$(
-            tput cuu "$__atuin_prompt_offset"
-            tput dl "$__atuin_prompt_offset"
-            tput il "$__atuin_prompt_offset"
-        )
-    fi
-    printf '%s\n' "$__atuin_clear_prompt$__atuin_prompt$__atuin_command"
+    __atuin_clear_prompt "$__atuin_prompt_offset"
+    printf '%s\n' "$__atuin_prompt$__atuin_command"
 
     # Add it to the bash history
     history -s "$__atuin_command"
@@ -164,7 +177,8 @@ __atuin_accept_line() {
     # so to work for a multiline prompt we need to print it ourselves,
     # then go to the beginning of the last line.
     __atuin_evaluate_prompt
-    printf '%s\r%s' "$__atuin_prompt" "$(tput el)"
+    printf '%s' "$__atuin_prompt"
+    __atuin_clear_prompt 0
 }
 
 __atuin_history() {