runtime(vim): add gf support for import and packadd in ftplugin

closes: #17881

Signed-off-by: lacygoill <lacygoill@lacygoill.me>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/autoload/vim.vim

@@ -0,0 +1,134 @@
+vim9script
+
+# Interface {{{1
+export def Find(editcmd: string) #{{{2
+    var curline: string = getline('.')
+
+    if curline =~ '^\s*\%(:\s*\)\=packadd!\=\s'
+        HandlePackaddLine(editcmd, curline)
+        return
+    endif
+
+    if curline =~ '^\s*\%(:\s*\)\=import\s'
+        HandleImportLine(editcmd, curline)
+        return
+    endif
+
+    try
+        execute 'normal! ' .. editcmd
+    catch
+        Error(v:exception)
+    endtry
+enddef
+#}}}1
+# Core {{{1
+def HandlePackaddLine(editcmd: string, curline: string) #{{{2
+    var pat: string = '^\s*packadd!\=\s\+\zs\S\+$'
+    var plugin: string = curline
+        ->matchstr(pat)
+        ->substitute('^vim-\|\.vim$', '', 'g')
+
+    if plugin == ''
+        try
+            execute 'normal! ' .. editcmd .. 'zv'
+        catch
+            Error(v:exception)
+            return
+        endtry
+    else
+        var split: string = editcmd[0] == 'g' ? 'edit' : editcmd[1] == 'g' ? 'tabedit' : 'split'
+        # In the  past, we passed  `runtime` to `getcompletion()`,  instead of
+        # `cmdline`.  But the  output was tricky to use,  because it contained
+        # paths relative to inconsistent root directories.
+        var files: list<string> = getcompletion($'edit **/plugin/{plugin}.vim', 'cmdline')
+            ->filter((_, path: string): bool => filereadable(path))
+            ->map((_, fname: string) => fname->fnamemodify(':p'))
+        if empty(files)
+            echo 'Could not find any plugin file for ' .. string(plugin)
+            return
+        endif
+        files->Open(split)
+    endif
+enddef
+
+def HandleImportLine(editcmd: string, curline: string) #{{{2
+    var fname: string
+    var import_cmd: string = '^\s*import\s\+\%(autoload\s\+\)\='
+    var import_alias: string = '\%(\s\+as\s\+\w\+\)\=$'
+    var import_string: string = import_cmd .. '\([''"]\)\zs.*\ze\1' .. import_alias
+    var import_expr: string = import_cmd .. '\zs.*\ze' .. import_alias
+    # the script is referred to by its name in a quoted string
+    if curline =~ import_string
+        fname = curline->matchstr(import_string)
+    # the script is referred to by an expression
+    elseif curline =~ import_expr
+        try
+            sandbox fname = curline
+                ->matchstr(import_expr)
+                ->eval()
+        catch
+            Error(v:exception)
+            return
+        endtry
+    endif
+
+    var filepath: string
+    if fname->isabsolutepath()
+        filepath = fname
+    elseif fname[0] == '.'
+        filepath = (expand('%:h') .. '/' .. fname)->simplify()
+    else
+        var subdir: string = curline =~ '^\s*import\s\+autoload\>' ? 'autoload' : 'import'
+        # Matching patterns in `'wildignore'` can be slow.
+        # Let's set `{nosuf}` to `true` to avoid `globpath()` to be slow.
+        filepath = globpath(&runtimepath, subdir .. '/' .. fname, true, true)
+            ->get(0, '')
+    endif
+
+    if !filepath->filereadable()
+        printf('E447: Can''t find file "%s" in path', fname)
+            ->Error()
+        return
+    endif
+
+    var how_to_split: string = {
+        gF: 'edit',
+        "\<C-W>F": 'split',
+        "\<C-W>gF": 'tab split',
+    }[editcmd]
+    execute how_to_split .. ' ' .. filepath
+enddef
+
+def Open(what: any, how: string) #{{{2
+    var fname: string
+    if what->typename() == 'list<string>'
+        if what->empty()
+            return
+        endif
+        fname = what[0]
+    else
+        if what->typename() != 'string'
+            return
+        endif
+        fname = what
+    endif
+
+    execute $'{how} {fname}'
+    cursor(1, 1)
+
+    # If there are several files to open, put them into an arglist.
+    if what->typename() == 'list<string>'
+            && what->len() > 1
+        var arglist: list<string> = what
+            ->copy()
+            ->map((_, f: string) => f->fnameescape())
+        execute $'arglocal {arglist->join()}'
+    endif
+enddef
+#}}}1
+# Util {{{1
+def Error(msg: string) #{{{2
+    echohl ErrorMsg
+    echomsg msg
+    echohl NONE
+enddef