Add a modeline support script (vim + kakoune options)

rc/modeline.kak

@@ -0,0 +1,126 @@
+##
+## modeline.kak by lenormf
+##
+
+## Currently supported modeline format: vim
+## Also supports kakoune options with a 'kak' or 'kakoune' prefix
+## Only a few options are supported, in order to prevent the
+## buffers from poking around the configuration too much
+
+# Set to 'true' to parse modelines in buffers
+decl bool modeline "true"
+# Amount of lines that will be checked at the beginning and the end of the buffer
+decl int modelines 5
+
+def -hidden _modeline-parse %{
+    %sh{
+        # Translate a vim option into the corresponding kakoune one
+        function translate_opt_vim {
+            readonly key="$1"
+            readonly value="$2"
+            local tr=""
+
+            case "${key}" in
+                so) ;&
+                scrolloff) tr="scrolloff ${value},${kak_opt_scrolloff##*,}";;
+                siso) ;&
+                sidescrolloff) tr="scrolloff ${kak_opt_scrolloff%%,*},${value}";;
+                ts) ;&
+                tabstop) tr="tabstop ${value}";;
+                sw) ;&
+                shiftwidth) tr="indentwidth ${value}";;
+                tw) ;&
+                textwidth) tr="autowrap_column ${value}";;
+                ff) ;&
+                fileformat)
+                    case "${value}" in
+                        unix) tr="eolformat lf";;
+                        dos) tr="eolformat crlf";;
+                        *) echo "Unsupported file format: ${value}" >&2;;
+                    esac
+                ;;
+                ft) ;&
+                filetype) tr="filetype ${value}";;
+                bomb) tr="BOM utf8";;
+                nobomb) tr="BOM none";;
+                *) echo "Unsupported vim variable: ${key}" >&2;;
+            esac
+
+            [ -n "${tr}" ] && echo "set buffer ${tr}"
+        }
+
+        # Pass a few whitelisted options to kakoune directly
+        function translate_opt_kakoune {
+            readonly key="$1"
+            readonly value="$2"
+            readonly OPTS_ALLOWED=(
+                scrolloff
+                tabstop
+                indentwidth
+                autowrap_column
+                eolformat
+                filetype
+                mimetype
+                BOM
+            )
+
+            grep -qw "${key}" <<< "${OPTS_ALLOWED[@]}" || {
+                echo "Unsupported kakoune variable: ${key}" >&2;
+                return;
+            }
+
+            echo "set buffer ${key} ${value}"
+        }
+
+        # The following subshell will keep the actual options of the modeline, and strip:
+        # - the text that leads the first option, according to the official vim modeline format
+        # - the trailing text after the last option, and an optional ':' sign before it
+        # It will also convert the ':' seperators beween the option=value pairs
+        # More info: http://vimdoc.sourceforge.net/htmldoc/options.html#modeline
+        options=(
+            $(sed -r -e 's/^(.+\s\w+:\s?(set?)?\s)//' \
+                     -e 's/:?\s[^a-zA-Z0-9_=-]+$//' \
+                     -e 's/:/ /g' <<< "${kak_selection}")
+        )
+
+        case "${kak_selection}" in
+            *vi:*) ;&
+            *vim:*) type_selection="vim";;
+            *kak:*) ;&
+            *kakoune:*) type_selection="kakoune";;
+            *) echo "echo -debug Unsupported modeline format";;
+        esac
+        [ -n "${type_selection}" ] || exit 1
+
+        for option in "${options[@]}"; do
+            name_option="${option%%=*}"
+            value_option="${option#*=}"
+
+            case "${type_selection}" in
+                vim) tr=$(translate_opt_vim "${name_option}" "${value_option}");;
+                kakoune) tr=$(translate_opt_kakoune "${name_option}" "${value_option}");;
+            esac
+
+            [ -n "${tr}" ] && echo "${tr}"
+        done
+    }
+}
+
+# Select the first and last `modelines` lines in the buffer, only keep modelines
+def -hidden _modeline-crunch %{
+    try %{
+        exec -draft "\%
+s(\`(^[^\n]*\n?){%opt{modelines}})|((^[^\n]*\n?){%opt{modelines}}\')<ret>
+s^[^\s]+?\s(vim?|kak(oune)?):\s?[^\n]+<ret>
+<a-s>
+:eval -draft -itersel _modeline-parse<ret>"
+    }
+}
+
+hook global BufOpen .* %{
+    %sh{
+        if [ "${kak_opt_modeline}" = true ]; then
+            echo "eval _modeline-crunch"
+        fi
+    }
+}