Install bash-preexec after our session is started.

- Invoke our install as part of PROMPT_COMMAND. This allows bash-preexec to be
  included at any point in our configuration and it should be invoked last.
  This makes sure we always have access to the DEBUG trap and that
  PROMPT_COMMAND is most likely untampered with.

- Should adress #21 and the occasional issue that gets created because
  bash-preexec is included improperly.

bash-preexec.sh

@@ -5,7 +5,7 @@
 #
 #
 # 'preexec' functions are executed before each interactive command is
-# executed, with the interactive command as its argument.  The 'precmd'
+# executed, with the interactive command as its argument. The 'precmd'
 # function is executed before each prompt is displayed.
 #
 # Author: Ryan Caloras (ryan@bashhub.com)
@@ -44,6 +44,10 @@ __bp_imported="defined"
 # functions, should they want it.
 __bp_last_command_ret_value="$?"
 
+# Command to set our preexec trap. It's invoked once via
+# PROMPT_COMMAND and then removed.
+__bp_trap_install_string="trap '__bp_preexec_invoke_exec' DEBUG;"
+
 # Remove ignorespace and or replace ignoreboth from HISTCONTROL
 # so we can accurately invoke preexec with a command from our
 # history even if it starts with a space.
@@ -137,7 +141,7 @@ __bp_preexec_invoke_exec() {
     # __bp_delay_install checks if we're in test. Needed for bats to run.
     # Prevents preexec from being invoked for functions in PS1
     if [[ ! -t 1 && -z "$__bp_delay_install" ]]; then
-      return
+        return
     fi
 
     if [[ -n "$COMP_LINE" ]]; then
@@ -192,14 +196,33 @@ __bp_preexec_invoke_exec() {
     done
 }
 
-# Execute this to set up preexec and precmd execution.
-__bp_preexec_and_precmd_install() {
+# Returns PROMPT_COMMAND with a semicolon appended
+# if it doesn't already have one.
+__bp_prompt_command_with_semi_colon() {
+    # Take our existing prompt command and append a semicolon to it
+    # if it doesn't already have one.
+    local existing_prompt_command
 
-    # Make sure this is bash that's running this and return otherwise.
-    if [[ -z "$BASH_VERSION" ]]; then
-        return 1;
+    if [[ -n "$PROMPT_COMMAND" ]]; then
+        existing_prompt_command=${PROMPT_COMMAND%${PROMPT_COMMAND##*[![:space:]]}}
+        existing_prompt_command=${existing_prompt_command%;}
+        existing_prompt_command=${existing_prompt_command/%/;}
+    else
+        existing_prompt_command=""
     fi
 
+    echo -n "$existing_prompt_command"
+}
+
+__bp_install() {
+
+    # Remove setting our trap from PROMPT_COMMAND
+    PROMPT_COMMAND="${PROMPT_COMMAND//$__bp_trap_install_string}"
+
+    # Remove this function from our PROMPT_COMMAND
+    PROMPT_COMMAND="${PROMPT_COMMAND//__bp_install;}"
+
+
     # Exit if we already have this installed.
     if [[ "$PROMPT_COMMAND" == *"__bp_precmd_invoke_cmd"* ]]; then
         return 1;
@@ -208,34 +231,55 @@ __bp_preexec_and_precmd_install() {
     # Adjust our HISTCONTROL Variable if needed.
     __bp_adjust_histcontrol
 
-
     # Set so debug trap will work be invoked in subshells.
     set -o functrace > /dev/null 2>&1
     shopt -s extdebug > /dev/null 2>&1
 
-    # Take our existing prompt command and append a semicolon to it
-    # if it doesn't already have one.
-    local existing_prompt_command
 
-    if [[ -n "$PROMPT_COMMAND" ]]; then
-        existing_prompt_command=${PROMPT_COMMAND%${PROMPT_COMMAND##*[![:space:]]}}
-        existing_prompt_command=${existing_prompt_command%;}
-        existing_prompt_command=${existing_prompt_command/%/;}
-    else
-        existing_prompt_command=""
-    fi
+    local existing_prompt_command
+    existing_prompt_command=$(__bp_prompt_command_with_semi_colon)
 
-    # Finally install our traps.
+    # Install our hooks in PROMPT_COMMAND to allow our trap to know when we've
+    # actually entered something.
     PROMPT_COMMAND="__bp_precmd_invoke_cmd; ${existing_prompt_command} __bp_interactive_mode;"
     trap '__bp_preexec_invoke_exec' DEBUG;
 
+
     # Add two functions to our arrays for convenience
     # of definition.
     precmd_functions+=(precmd)
     preexec_functions+=(preexec)
+
+    # Since this is in PROMPT_COMMAND, invoke any precmd functions we have defined.
+    __bp_precmd_invoke_cmd
+    # Put us in interactive mode for our first command.
+    __bp_interactive_mode
+}
+
+# Sets our trap and __bp_install as part of our PROMPT_COMMAND to install
+# after our session has started. This allows bash-preexec to be inlucded
+# at any point in our bash profile. Ideally we could set our trap inside
+# __bp_install, but if a trap already exists it'll only set locally to
+# the function.
+__bp_install_after_session_init() {
+
+    # Make sure this is bash that's running this and return otherwise.
+    if [[ -z "$BASH_VERSION" ]]; then
+        return 1;
+    fi
+
+    local existing_prompt_command
+    existing_prompt_command=$(__bp_prompt_command_with_semi_colon)
+
+
+    __bp_original_prompt_command="$existing_prompt_command"
+
+    # Add our installation to be done last via our PROMPT_COMMAND. These are
+    # removed by __bp_install when it's invoked so it only runs once.
+    PROMPT_COMMAND="${existing_prompt_command} $__bp_trap_install_string __bp_install;"
 }
 
 # Run our install so long as we're not delaying it.
 if [[ -z "$__bp_delay_install" ]]; then
-    __bp_preexec_and_precmd_install
+    __bp_install_after_session_init
 fi;

test/bash-preexec.bats

@@ -13,20 +13,35 @@ test_preexec_echo() {
   echo "$1"
 }
 
-@test "__bp_preexec_and_precmd_install should exit with 1 if we're not using bash" {
+@test "__bp_install_after_session_init should exit with 1 if we're not using bash" {
   unset BASH_VERSION
-  run '__bp_preexec_and_precmd_install'
+  run '__bp_install_after_session_init'
   [[ $status == 1 ]]
   [[ -z "$output" ]]
 }
 
-@test "__bp_preexec_and_precmd_install should exit if it's already installed" {
+@test "__bp_install should exit if it's already installed" {
   PROMPT_COMMAND="some_other_function; __bp_precmd_invoke_cmd;"
-  run '__bp_preexec_and_precmd_install'
+  run '__bp_install'
   [[ $status == 1 ]]
   [[ -z "$output" ]]
 }
 
+@test "__bp_install should remove trap and itself from PROMPT_COMMAND" {
+  trap_string="trap '__bp_preexec_invoke_exec' DEBUG;"
+  PROMPT_COMMAND="some_other_function; $trap_string __bp_install;"
+
+  [[ $PROMPT_COMMAND  == *"$trap_string"* ]]
+  [[ $PROMPT_COMMAND  = *"__bp_install;"* ]]
+
+  __bp_install
+
+  [[ $PROMPT_COMMAND  != *"$trap_string"* ]]
+  [[ $PROMPT_COMMAND  != *"__bp_install;"* ]]
+  [[ -z "$output" ]]
+}
+
+
 @test "No functions defined for preexec should simply return" {
     run '__bp_preexec_invoke_exec'
     [[ $status == 0 ]]

test/include-test.bats

@@ -9,6 +9,6 @@
 @test "should import of not defined" {
   unset __bp_imported
   source "${BATS_TEST_DIRNAME}/../bash-preexec.sh"
-  [[ -n $(type -t __bp_preexec_and_precmd_install) ]]
+  [[ -n $(type -t __bp_install) ]]
 }