feat(bash): Support right prompt and transience (#4902)

* Support right prompt in bash

* Docs for transience in bash

* Apply suggestions from review

* Simplify conditional

* Use ble.sh hooks, if available

* Properly quote args

* Use BLE_PIPESTATUS

* Update starship.bash

* Update src/init/starship.bash

Co-authored-by: Koichi Murase <myoga.murase@gmail.com>

---------

Co-authored-by: Koichi Murase <myoga.murase@gmail.com>

2 files changed, 54 insertions, 5 deletions

diff --git a/docs/advanced-config/README.md b/docs/advanced-config/README.md
index 13f30c0c4..b728a632a 100644
--- a/docs/advanced-config/README.md
+++ b/docs/advanced-config/README.md
@@ -106,6 +106,41 @@ starship init fish | source
 enable_transience
 ```
 
+## TransientPrompt and TransientRightPrompt in Bash
+
+The [Ble.sh](https://github.com/akinomyoga/ble.sh) framework allows you to replace
+the previous-printed prompt with custom strings. This is useful in cases where all
+the prompt information is not always needed. To enable this, put this in `~/.bashrc`
+`bleopt prompt_ps1_transient=<value>`:
+
+The \<value\> here is a colon-separated list of `always`, `same-dir` and `trim`.
+When `prompt_ps1_final` is empty and this option has a non-empty value,
+the prompt specified by `PS1` is erased on leaving the current command line.
+If the value contains a field `trim`, only the last line of multiline `PS1` is
+preserved and the other lines are erased. Otherwise, the command line will be
+redrawn as if `PS1=` is specified. When a field `same-dir` is contained in the
+value and the current working directory is different from the final directory of
+the previous command line, this option `prompt_ps1_transient` is ignored.
+
+Make the following changes to your `~/.bashrc` to customize what gets displayed on
+the left and on the right:
+
+- To customize what the left side of input gets replaced with, configure the
+  `prompt_ps1_final` Ble.sh option. For example, to display Starship's `character`
+  module here, you would do
+
+```bash
+bleopt prompt_ps1_final="$(starship module character)"
+```
+
+- To customize what the right side of input gets replaced with, configure the
+  `prompt_rps1_final` Ble.sh option. For example, to display
+  the time at which the last command was started here, you would do
+
+```bash
+bleopt prompt_rps1_final="$(starship module time)"
+```
+
 ## Custom pre-prompt and pre-execution Commands in Cmd
 
 Clink provides extremely flexible APIs to run pre-prompt and pre-exec commands
@@ -261,7 +296,9 @@ not explicitly used in either `format` or `right_format`.
 Note: The right prompt is a single line following the input location. To right align modules above
 the input line in a multi-line prompt, see the [`fill` module](/config/#fill).
 
-`right_format` is currently supported for the following shells: elvish, fish, zsh, xonsh, cmd, nushell.
+`right_format` is currently supported for the following shells: elvish, fish, zsh, xonsh, cmd, nushell, bash.
+
+Note: The [Ble.sh](https://github.com/akinomyoga/ble.sh) framework should be installed in order to use right prompt in bash.
 
 ### Example
 
diff --git a/src/init/starship.bash b/src/init/starship.bash
index b7f7cb0e5..5a62be857 100644
--- a/src/init/starship.bash
+++ b/src/init/starship.bash
@@ -33,6 +33,9 @@ starship_preexec() {
 starship_precmd() {
     # Save the status, because commands in this pipeline will change $?
     STARSHIP_CMD_STATUS=$? STARSHIP_PIPE_STATUS=(${PIPESTATUS[@]})
+    if [[ ${BLE_ATTACHED-} && ${#BLE_PIPESTATUS[@]} -gt 0 ]]; then
+        STARSHIP_PIPE_STATUS=("${BLE_PIPESTATUS[@]}")
+    fi
     if [[ "${#BP_PIPESTATUS[@]}" -gt "${#STARSHIP_PIPE_STATUS[@]}" ]]; then
         STARSHIP_PIPE_STATUS=(${BP_PIPESTATUS[@]})
     fi
@@ -64,21 +67,30 @@ starship_precmd() {
 
     eval "$_PRESERVED_PROMPT_COMMAND"
 
+    local -a ARGS=(--terminal-width="${COLUMNS}" --status="${STARSHIP_CMD_STATUS}" --pipestatus="${STARSHIP_PIPE_STATUS[*]}" --jobs="${NUM_JOBS}")
     # Prepare the timer data, if needed.
     if [[ $STARSHIP_START_TIME ]]; then
         STARSHIP_END_TIME=$(::STARSHIP:: time)
         STARSHIP_DURATION=$((STARSHIP_END_TIME - STARSHIP_START_TIME))
-        PS1="$(::STARSHIP:: prompt --terminal-width="$COLUMNS" --status=$STARSHIP_CMD_STATUS --pipestatus="${STARSHIP_PIPE_STATUS[*]}" --jobs="$NUM_JOBS" --cmd-duration=$STARSHIP_DURATION)"
+        ARGS+=( --cmd-duration="${STARSHIP_DURATION}")
         unset STARSHIP_START_TIME
-    else
-        PS1="$(::STARSHIP:: prompt --terminal-width="$COLUMNS" --status=$STARSHIP_CMD_STATUS --pipestatus="${STARSHIP_PIPE_STATUS[*]}" --jobs="$NUM_JOBS")"
+    fi
+    PS1="$(::STARSHIP:: prompt "${ARGS[@]}")"
+    if [[ ${BLE_ATTACHED-} ]]; then
+        local nlns=${PS1//[!$'\n']}
+        bleopt prompt_rps1="$nlns$(::STARSHIP:: prompt --right "${ARGS[@]}")"
     fi
     STARSHIP_PREEXEC_READY=true  # Signal that we can safely restart the timer
 }
 
+# If the user appears to be using https://github.com/akinomyoga/ble.sh,
+# then hook our functions into their framework.
+if [[ ${BLE_VERSION-} && _ble_version -ge 400 ]]; then
+    blehook PREEXEC!='starship_preexec "$_"'
+    blehook PRECMD!='starship_precmd'
 # If the user appears to be using https://github.com/rcaloras/bash-preexec,
 # then hook our functions into their framework.
-if [[ "${__bp_imported:-}" == "defined" || $preexec_functions || $precmd_functions ]]; then
+elif [[ "${__bp_imported:-}" == "defined" || $preexec_functions || $precmd_functions ]]; then
     # bash-preexec needs a single function--wrap the args into a closure and pass
     starship_preexec_all(){ starship_preexec "$_"; }
     preexec_functions+=(starship_preexec_all)