Add support for appending to environment variables

ament_package/template/package_level/local_setup.bat.in

@@ -23,7 +23,7 @@ set "AMENT_CURRENT_PREFIX="
 goto:eof
 
 
-:: Append non-duplicate values to environment variables
+:: Append values to environment variables
 :: using semicolons as separators and avoiding leading separators.
 :: first argument: the name of the result variable
 :: second argument: the value
@@ -45,6 +45,37 @@ goto:eof
   )
 goto:eof
 
+:: Append non-duplicate values to environment variables
+:: using semicolons as separators and avoiding trailing separators.
+:: first argument: the name of the result variable
+:: second argument: the value
+:ament_append_unique_value
+  setlocal enabledelayedexpansion
+  :: arguments
+  set "listname=%~1"
+  set "value=%~2"
+  :: expand the list variable
+  set "list=!%listname%!"
+  :: check if the list contains the value
+  set "is_duplicate="
+  if "%list%" NEQ "" (
+    for %%v in ("%list:;=";"%") do (
+      if "%%~v" == "%value%" set "is_duplicate=1"
+    )
+  )
+  :: if it is not a duplicate append it
+  if "%is_duplicate%" == "" (
+    :: if not empty, append a semi-colon
+    if "!list!" NEQ "" set "list=!list!;"
+    :: append the value
+    set "list=!list!%value%"
+  )
+  endlocal & (
+    :: set result variable in parent scope
+    set "%~1=%list%"
+  )
+goto:eof
+
 :: Call the specified batch file and output the name when tracing is requested.
 :: first argument: the batch file
 :call_file

ament_package/template/package_level/local_setup.sh.in

@@ -42,6 +42,57 @@ ament_append_value() {
   unset _listname
 }
 
+# function to append non-duplicate values to environment variables
+# using colons as separators and avoiding leading separators
+ament_append_unique_value() {
+  # arguments
+  _listname=$1
+  _value=$2
+  #echo "listname $_listname"
+  #eval echo "list value \$$_listname"
+  #echo "value $_value"
+
+  # check if the list contains the value
+  eval _values=\$$_listname
+  _duplicate=
+  _ament_append_unique_value_IFS=$IFS
+  IFS=":"
+  if [ "$AMENT_SHELL" = "zsh" ]; then
+    ament_zsh_to_array _values
+  fi
+  for _item in $_values; do
+    # ignore empty strings
+    if [ -z "$_item" ]; then
+      continue
+    fi
+    if [ $_item = $_value ]; then
+      _duplicate=1
+    fi
+  done
+  unset _item
+
+  # append only non-duplicates
+  if [ -z "$_duplicate" ]; then
+    # avoid leading separator
+    if [ -z "$_values" ]; then
+      eval $_listname=\"$_value\"
+      #eval echo "set list \$$_listname"
+    else
+      # field separator must not be a colon
+      unset IFS
+      eval $_listname=\"\$$_listname:$_value\"
+      #eval echo "append list \$$_listname"
+    fi
+  fi
+  IFS=$_ament_append_unique_value_IFS
+  unset _ament_append_unique_value_IFS
+  unset _duplicate
+  unset _values
+
+  unset _value
+  unset _listname
+}
+
 # function to prepend non-duplicate values to environment variables
 # using colons as separators and avoiding trailing separators
 ament_prepend_unique_value() {

ament_package/template/prefix_level/_local_setup_util.py

@@ -15,6 +15,7 @@
 FORMAT_STR_INVOKE_SCRIPT = None
 FORMAT_STR_REMOVE_TRAILING_SEPARATOR = None
 
+DSV_TYPE_APPEND_NON_DUPLICATE = 'append-non-duplicate'
 DSV_TYPE_PREPEND_NON_DUPLICATE = 'prepend-non-duplicate'
 DSV_TYPE_PREPEND_NON_DUPLICATE_IF_EXISTS = 'prepend-non-duplicate-if-exists'
 DSV_TYPE_SET = 'set'
@@ -27,6 +28,7 @@ def main(argv=sys.argv[1:]):  # noqa: D103
     global FORMAT_STR_SET_ENV_VAR
     global FORMAT_STR_USE_ENV_VAR
     global FORMAT_STR_INVOKE_SCRIPT
+    global FORMAT_STR_REMOVE_LEADING_SEPARATOR
     global FORMAT_STR_REMOVE_TRAILING_SEPARATOR
 
     parser = argparse.ArgumentParser(
@@ -46,6 +48,8 @@ def main(argv=sys.argv[1:]):  # noqa: D103
         FORMAT_STR_USE_ENV_VAR = '${name}'
         FORMAT_STR_INVOKE_SCRIPT = 'AMENT_CURRENT_PREFIX="{prefix}" ' \
             '_ament_prefix_sh_source_script "{script_path}"'
+        FORMAT_STR_REMOVE_LEADING_SEPARATOR = 'if [ "$(echo -n ${name} | ' \
+            'head -c 1)" = ":" ]; then export {name}=${{{name}#?}} ; fi'
         FORMAT_STR_REMOVE_TRAILING_SEPARATOR = 'if [ "$(echo -n ${name} | ' \
             'tail -c 1)" = ":" ]; then export {name}=${{{name}%?}} ; fi'
     elif args.primary_extension == 'bat':
@@ -55,6 +59,8 @@ def main(argv=sys.argv[1:]):  # noqa: D103
         FORMAT_STR_INVOKE_SCRIPT = \
             'call:_ament_prefix_bat_call_script "{script_path}"'
         # can't use `if` here since each line is being `call`-ed
+        FORMAT_STR_REMOVE_LEADING_SEPARATOR = \
+            'call:_ament_prefix_bat_strip_leading_semicolon "{name}"'
         FORMAT_STR_REMOVE_TRAILING_SEPARATOR = \
             'call:_ament_prefix_bat_strip_trailing_semicolon "{name}"'
     else:
@@ -75,7 +81,7 @@ def main(argv=sys.argv[1:]):  # noqa: D103
         ):
             print(line)
 
-    for line in _remove_trailing_separators():
+    for line in _remove_ending_separators():
         print(line)
 
 
@@ -300,6 +306,7 @@ def handle_dsv_types_except_source(type_, remainder, prefix):
         else:
             assert False
     elif type_ in (
+        DSV_TYPE_APPEND_NON_DUPLICATE,
         DSV_TYPE_PREPEND_NON_DUPLICATE,
         DSV_TYPE_PREPEND_NON_DUPLICATE_IF_EXISTS
     ):
@@ -325,6 +332,8 @@ def handle_dsv_types_except_source(type_, remainder, prefix):
                         f'path: {value}'
                     commands.append(
                         FORMAT_STR_COMMENT_LINE.format_map({'comment': comment}))
+            elif type_ == DSV_TYPE_APPEND_NON_DUPLICATE:
+                commands += _append_unique_value(env_name, value)
             else:
                 commands += _prepend_unique_value(env_name, value)
     else:
@@ -336,6 +345,28 @@ def handle_dsv_types_except_source(type_, remainder, prefix):
 env_state = {}
 
 
+def _append_unique_value(name, value):
+    global env_state
+    if name not in env_state:
+        if os.environ.get(name):
+            env_state[name] = set(os.environ[name].split(os.pathsep))
+        else:
+            env_state[name] = set()
+    # append even if the variable has not been set yet, in case a shell script sets the
+    # same variable without the knowledge of this Python script.
+    # later _remove_ending_separators() will cleanup any unintentional trailing separator
+    extend = FORMAT_STR_USE_ENV_VAR.format_map({'name': name}) + os.pathsep
+    line = FORMAT_STR_SET_ENV_VAR.format_map(
+        {'name': name, 'value': extend + value})
+    if value not in env_state[name]:
+        env_state[name].add(value)
+    else:
+        if not _include_comments():
+            return []
+        line = FORMAT_STR_COMMENT_LINE.format_map({'comment': line})
+    return [line]
+
+
 def _prepend_unique_value(name, value):
     global env_state
     if name not in env_state:
@@ -345,7 +376,7 @@ def _prepend_unique_value(name, value):
             env_state[name] = set()
     # prepend even if the variable has not been set yet, in case a shell script sets the
     # same variable without the knowledge of this Python script.
-    # later _remove_trailing_separators() will cleanup any unintentional trailing separator
+    # later _remove_ending_separators() will cleanup any unintentional trailing separator
     extend = os.pathsep + FORMAT_STR_USE_ENV_VAR.format_map({'name': name})
     line = FORMAT_STR_SET_ENV_VAR.format_map(
         {'name': name, 'value': value + extend})
@@ -358,15 +389,16 @@ def _prepend_unique_value(name, value):
     return [line]
 
 
-def _remove_trailing_separators():
+def _remove_ending_separators():
     global env_state
     commands = []
     for name in env_state:
         # skip variables that already had values before this script started prepending
         if name in os.environ:
             continue
-        commands += [FORMAT_STR_REMOVE_TRAILING_SEPARATOR.format_map(
-            {'name': name})]
+        commands += [
+            FORMAT_STR_REMOVE_LEADING_SEPARATOR.format_map({'name': name}),
+            FORMAT_STR_REMOVE_TRAILING_SEPARATOR.format_map({'name': name})]
     return commands
 
 

ament_package/template/prefix_level/local_setup.bat.in

@@ -64,6 +64,20 @@ goto:eof
 goto:eof
 
 
+:: strip a leading semicolon from an environment variable if applicable
+:: first argument: the environment variable name
+:_ament_prefix_bat_strip_leading_semicolon
+  setlocal enabledelayedexpansion
+  set "name=%~1"
+  set "value=!%name%!"
+  if "%value:~0,1%"==";" set "value=%value:~1%"
+  :: set result variable in parent scope
+  endlocal & (
+    set "%~1=%value%"
+  )
+goto:eof
+
+
 :: strip a trailing semicolon from an environment variable if applicable
 :: first argument: the environment variable name
 :_ament_prefix_bat_strip_trailing_semicolon