feat: add support for fish

ament_package/template/package_level/local_setup.fish.in

@@ -0,0 +1,64 @@
+# generated from ament_package/template/package_level/local_setup.fish.in
+
+# since this file is sourced use the destination set at configure time
+# and override it with COLCON_CURRENT_PREFIX when provided
+set -l AMENT_CURRENT_PREFIX "@CMAKE_INSTALL_PREFIX@"
+if test -n "$COLCON_CURRENT_PREFIX"
+    set AMENT_CURRENT_PREFIX "$COLCON_CURRENT_PREFIX"
+end
+if not test -d "$AMENT_CURRENT_PREFIX"
+    echo "The compile-time prefix path '$AMENT_CURRENT_PREFIX' doesn't exist. \
+Consider sourcing a different shell extension." 1>&2
+    set -e AMENT_CURRENT_PREFIX
+    return 1
+end
+set -l _package_local_setup_AMENT_CURRENT_PREFIX "$AMENT_CURRENT_PREFIX"
+
+# function to append values to environment variables
+# using colons as separators and avoiding leading separators
+function ament_append_value
+    set -l _name $argv[1]
+    set -l _val $argv[2]
+    if set -q $_name; and test -n "$$_name"
+        set -gx $_name "$$_name:$_val"
+    else
+        set -gx $_name "$_val"
+    end
+end
+
+# unset AMENT_ENVIRONMENT_HOOKS
+# if not appending to them for return
+if not set -q AMENT_RETURN_ENVIRONMENT_HOOKS
+    set -e AMENT_ENVIRONMENT_HOOKS
+end
+
+# restore AMENT_CURRENT_PREFIX before evaluating environment hooks
+set AMENT_CURRENT_PREFIX "$_package_local_setup_AMENT_CURRENT_PREFIX"
+
+# list all environment hooks of this package
+@ENVIRONMENT_HOOKS@
+
+functions -e ament_append_value
+
+# source all shell-specific environment hooks of this package
+# if not returning them
+if not set -q AMENT_RETURN_ENVIRONMENT_HOOKS
+    for _hook in (string split ":" -- "$AMENT_ENVIRONMENT_HOOKS")
+        if string match -q -- "*.fish" "$_hook"
+            set -gx AMENT_CURRENT_PREFIX \
+                "$_package_local_setup_AMENT_CURRENT_PREFIX"
+            if test -f "$_hook"
+                if test -n "$AMENT_TRACE_SETUP_FILES"
+                    echo "# source \"$_hook\""
+                end
+                source "$_hook"
+            end
+        end
+    end
+    set -e AMENT_ENVIRONMENT_HOOKS
+end
+
+set -e _package_local_setup_AMENT_CURRENT_PREFIX
+# reset AMENT_CURRENT_PREFIX after each package
+# allowing to source multiple package-level setup files
+set -e AMENT_CURRENT_PREFIX

ament_package/template/prefix_level/_local_setup_util.py

@@ -15,13 +15,20 @@
 FORMAT_STR_INVOKE_SCRIPT = None
 FORMAT_STR_REMOVE_TRAILING_SEPARATOR = None
 
+# Track primary extension so helpers can apply shell-specific behavior.
+PRIMARY_EXTENSION = 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'
 DSV_TYPE_SET_IF_UNSET = 'set-if-unset'
 DSV_TYPE_SOURCE = 'source'
 
+# Fish treats PATH / MANPATH / CDPATH as list variables.
+# Use fish list prepend/append syntax for these vars.
+_FISH_LIST_VARS = {'PATH', 'MANPATH', 'CDPATH'}
+
 
 def main(argv=sys.argv[1:]):  # noqa: D103
     global FORMAT_STR_COMMENT_LINE
@@ -30,6 +37,7 @@ def main(argv=sys.argv[1:]):  # noqa: D103
     global FORMAT_STR_INVOKE_SCRIPT
     global FORMAT_STR_REMOVE_LEADING_SEPARATOR
     global FORMAT_STR_REMOVE_TRAILING_SEPARATOR
+    global PRIMARY_EXTENSION
 
     parser = argparse.ArgumentParser(
         description='Output shell commands for the packages in topological '
@@ -42,6 +50,8 @@ def main(argv=sys.argv[1:]):  # noqa: D103
         help='The additional file extension to be considered')
     args = parser.parse_args(argv)
 
+    PRIMARY_EXTENSION = args.primary_extension
+
     if args.primary_extension == 'sh':
         FORMAT_STR_COMMENT_LINE = '# {comment}'
         FORMAT_STR_SET_ENV_VAR = 'export {name}="{value}"'
@@ -61,6 +71,31 @@ def main(argv=sys.argv[1:]):  # noqa: D103
             'call:_ament_prefix_bat_strip_leading_semicolon "{name}"'
         FORMAT_STR_REMOVE_TRAILING_SEPARATOR = \
             'call:_ament_prefix_bat_strip_trailing_semicolon "{name}"'
+    elif args.primary_extension == 'fish':
+        FORMAT_STR_COMMENT_LINE = '# {comment}'
+        FORMAT_STR_SET_ENV_VAR = 'set -gx {name} "{value}"'
+        FORMAT_STR_USE_ENV_VAR = '${name}'
+        # Keep AMENT_CURRENT_PREFIX local to this begin/end block
+        # so that it doesn't affect other scripts that are sourced.
+        FORMAT_STR_INVOKE_SCRIPT = (
+            'begin\n'
+            '    set -lx AMENT_CURRENT_PREFIX "{prefix}"\n'
+            '    if test -f "{script_path}"\n'
+            '        if test -n "$AMENT_TRACE_SETUP_FILES"\n'
+            '            echo "# source \\"{script_path}\\""\n'
+            '        end\n'
+            '        source "{script_path}"\n'
+            '    else\n'
+            '        echo "not found: \\"{script_path}\\"" 1>&2\n'
+            '    end\n'
+            'end'
+        )
+        FORMAT_STR_REMOVE_LEADING_SEPARATOR = (
+            "set -gx {name} (string replace --regex '^:' '' -- \"${name}\")"
+        )
+        FORMAT_STR_REMOVE_TRAILING_SEPARATOR = (
+            "set -gx {name} (string replace --regex ':$' '' -- \"${name}\")"
+        )
     else:
         assert False, 'Unknown primary extension: ' + args.primary_extension
 
@@ -352,6 +387,22 @@ def _append_unique_value(name, value):
             env_state[name] = set(os.environ[name].split(os.pathsep))
         else:
             env_state[name] = set()
+
+    if PRIMARY_EXTENSION == 'fish' and name in _FISH_LIST_VARS:
+        # Fish list variables: use list-append syntax to avoid space-joining.
+        if value not in env_state[name]:
+            env_state[name].add(value)
+            line = (
+                'contains -- "{value}" ${name}; '
+                'or set -gx {name} ${name} "{value}"'
+            ).format(name=name, value=value)
+        else:
+            if not _include_comments():
+                return []
+            line = FORMAT_STR_COMMENT_LINE.format_map(
+                {'comment': 'already in {}: {}'.format(name, value)})
+        return [line]
+
     # 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
@@ -373,6 +424,22 @@ def _prepend_unique_value(name, value):
             env_state[name] = set(os.environ[name].split(os.pathsep))
         else:
             env_state[name] = set()
+
+    if PRIMARY_EXTENSION == 'fish' and name in _FISH_LIST_VARS:
+        # Fish list variables: use list-prepend syntax to avoid space-joining.
+        if value not in env_state[name]:
+            env_state[name].add(value)
+            line = (
+                'contains -- "{value}" ${name}; '
+                'or set -gx {name} "{value}" ${name}'
+            ).format(name=name, value=value)
+        else:
+            if not _include_comments():
+                return []
+            line = FORMAT_STR_COMMENT_LINE.format_map(
+                {'comment': 'already in {}: {}'.format(name, value)})
+        return [line]
+
     # 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_ending_separators() will cleanup any unintentional trailing separator
@@ -394,6 +461,10 @@ def _remove_ending_separators():
         # skip variables that already had values before this script started prepending
         if name in os.environ:
             continue
+        # Fish list variables don't use the colon-string approach so they
+        # never accumulate stray separators.
+        if PRIMARY_EXTENSION == 'fish' and name in _FISH_LIST_VARS:
+            continue
         commands += [
             FORMAT_STR_REMOVE_LEADING_SEPARATOR.format_map({'name': name}),
             FORMAT_STR_REMOVE_TRAILING_SEPARATOR.format_map({'name': name})]
@@ -408,8 +479,14 @@ def _set(name, value):
 
 
 def _set_if_unset(name, value):
-    line = FORMAT_STR_SET_ENV_VAR.format_map(
-        {'name': name, 'value': value})
+    if PRIMARY_EXTENSION == 'fish':
+        # Fish: only set when NAME is unset or empty.
+        # `set -q` checks existence; `test -n` checks non-empty value.
+        line = 'set -q {name}; and test -n "${name}"; or set -gx {name} "{value}"'.format(
+            name=name, value=value)
+    else:
+        line = FORMAT_STR_SET_ENV_VAR.format_map(
+            {'name': name, 'value': value})
     if env_state.get(name, os.environ.get(name)):
         line = FORMAT_STR_COMMENT_LINE.format_map({'comment': line})
     return [line]

ament_package/template/prefix_level/local_setup.fish.in

@@ -0,0 +1,44 @@
+# generated from ament_package/template/prefix_level/local_setup.fish.in
+
+# Prefer AMENT_CURRENT_PREFIX (set by setup.fish); otherwise use install-time prefix.
+set -l _ament_prefix_fish_AMENT_CURRENT_PREFIX "@CMAKE_INSTALL_PREFIX@"
+if test -n "$AMENT_CURRENT_PREFIX"
+    set _ament_prefix_fish_AMENT_CURRENT_PREFIX "$AMENT_CURRENT_PREFIX"
+end
+
+if not test -d "$_ament_prefix_fish_AMENT_CURRENT_PREFIX"
+    echo "The build-time prefix \"$_ament_prefix_fish_AMENT_CURRENT_PREFIX\" \
+doesn't exist. Either source a script for a different shell or set \
+AMENT_CURRENT_PREFIX explicitly." 1>&2
+    set -e _ament_prefix_fish_AMENT_CURRENT_PREFIX
+    return 1
+end
+
+# Locate a Python interpreter.
+set -l _ament_python_executable "@ament_package_PYTHON_EXECUTABLE@"
+if test -n "$AMENT_PYTHON_EXECUTABLE"
+    set _ament_python_executable "$AMENT_PYTHON_EXECUTABLE"
+end
+if not test -f "$_ament_python_executable"
+    if command -v python3 > /dev/null 2>&1
+        set _ament_python_executable (python3 -c "import sys; print(sys.executable)")
+    else
+        echo "error: unable to find a python3 executable" 1>&2
+        set -e _ament_prefix_fish_AMENT_CURRENT_PREFIX
+        return 1
+    end
+end
+
+# Generate fish setup commands in topological order and source them.
+# psub turns Python stdout into a real file path for source.
+# Generated commands use fish-native env handling (set -gx and list PATH).
+if test -n "$AMENT_TRACE_SETUP_FILES"
+    echo "# source (\"$_ament_python_executable\" \
+\"$_ament_prefix_fish_AMENT_CURRENT_PREFIX/_local_setup_util.py\" fish | psub)"
+end
+
+source (command "$_ament_python_executable" \
+    "$_ament_prefix_fish_AMENT_CURRENT_PREFIX/_local_setup_util.py" fish | psub)
+
+set -e _ament_python_executable
+set -e _ament_prefix_fish_AMENT_CURRENT_PREFIX

ament_package/template/prefix_level/setup.fish

@@ -0,0 +1,56 @@
+# copied from ament_package/template/prefix_level/setup.fish
+
+# Determine prefix from this script's location at runtime.
+# 'status -f' gives the path of the currently sourced file in fish.
+set -l AMENT_CURRENT_PREFIX (builtin realpath (dirname (status -f)))
+
+# trace output
+if test -n "$AMENT_TRACE_SETUP_FILES"
+    echo "# source \"$AMENT_CURRENT_PREFIX/local_setup.fish\""
+end
+
+# Build ordered prefixes (same order as setup.sh.in) for overlay workspaces.
+# Keep dedup inline: fish functions can't update caller local vars.
+set -l _UNIQUE_PREFIX_PATH
+set -l _parent_index \
+    "$AMENT_CURRENT_PREFIX/share/ament_index/resource_index/parent_prefix_path"
+
+if test -d "$_parent_index"
+    for _resource in (command ls "$_parent_index" 2>/dev/null | command sort)
+        read -z _content < "$_parent_index/$_resource" 2>/dev/null; or set _content ""
+        set -l _paths (string split ":" -- "$_content")
+        # Reverse the list (similar to setup.sh)
+        set -l _reversed
+        for _p in $_paths
+            if test "$_p" = "{prefix}"
+                set _p "$AMENT_CURRENT_PREFIX"
+            end
+            set _reversed "$_p" $_reversed
+        end
+        for _p in $_reversed
+            if not contains -- "$_p" $_UNIQUE_PREFIX_PATH
+                set -a _UNIQUE_PREFIX_PATH "$_p"
+            end
+        end
+    end
+end
+
+# Always include the current prefix last (highest priority).
+if not contains -- "$AMENT_CURRENT_PREFIX" $_UNIQUE_PREFIX_PATH
+    set -a _UNIQUE_PREFIX_PATH "$AMENT_CURRENT_PREFIX"
+end
+
+# Source local_setup.fish for each prefix in order.
+for _prefix_path in $_UNIQUE_PREFIX_PATH
+    set -gx AMENT_CURRENT_PREFIX "$_prefix_path"
+    if test -f "$_prefix_path/local_setup.fish"
+        if test -n "$AMENT_TRACE_SETUP_FILES"
+            echo "# source \"$_prefix_path/local_setup.fish\""
+        end
+        source "$_prefix_path/local_setup.fish"
+    end
+end
+
+set -e AMENT_CURRENT_PREFIX
+set -e _UNIQUE_PREFIX_PATH
+set -e _parent_index

ament_package/templates.py

@@ -31,6 +31,7 @@ def get_package_level_template_names(all_platforms=False):
     names = ['local_setup.%s.in' % ext for ext in [
         'bash',
         'bat',
+        'fish',
         'sh',
         'zsh',
     ]]
@@ -52,6 +53,7 @@ def get_prefix_level_template_names(*, all_platforms=False):
     ]
     names = ['local_setup.%s' % ext for ext in extensions] + \
         ['setup.%s' % ext for ext in extensions] + \
+        ['local_setup.fish.in', 'setup.fish'] + \
         ['_local_setup_util.py']
     if not all_platforms:
         names = [name for name in names if _is_platform_specific_extension(name)]