initial version to replace line completion

lc.vim

@@ -1,16 +1,20 @@
 vim9script
 
-def GetMatch(base: string, line: string): list<any>
+def GetMatch(base: string, line: string, add_base: bool): list<any>
     var s = base
     while stridx(line, s) == -1
         s = strpart(s, 1)
         if strlen(s) == 0
-            return [0, ""]
+            return [0, ""] # vim ignores these
         endif
     endwhile
     const idx = stridx(line, s)
     const slen = strlen(s)
+    if add_base
         return [slen, base .. strpart(line, idx + slen)]
+    else
+        return [slen, strpart(line, idx + slen)]
+    endif
 enddef
 
 def LineSuffixCompl(findstart: bool, base: string): any
@@ -22,9 +26,26 @@ def LineSuffixCompl(findstart: bool, base: string): any
         ->flattennew()
         ->sort()
         ->uniq()
-        ->map( (_, v) => GetMatch(base, v) )
+        ->map( (_, v) => GetMatch(base, v, v:true) )
         ->sort( (x, y) => y[0] - x[0] )
         ->map( (_, v) => v[1] )
 enddef
 
-setlocal completefunc=LineSuffixCompl
+def DoLSCmpl(): string
+    const base = getline('.')
+    const lines = getbufinfo()
+        ->map( (_, buf) => getbufline(buf["bufnr"], 1, "$"))
+        ->flattennew()
+        ->sort()
+        ->uniq()
+        ->map( (_, v) => GetMatch(base, v, v:false) )
+        ->sort( (x, y) => y[0] - x[0] )
+        ->map( (_, v) => v[1] )
+
+    complete(col('.'), lines)
+    return ''
+enddef
+
+# inoremap <C-X><C-L> <C-R>=<SID>DoLSCmpl()<CR>
+
+set completefunc=LineSuffixCompl