Extract GetLongestSuffix and add quick test

exp.txt

@@ -1,32 +0,0 @@
-
-fo
-bar
-bar
-hello
-bar
-hello
-hello
-f
-abcd
-fo
-hello
-fo
-bcd
-hello world and ha ha ha
-foo bar and ha ha ha
-xdfadf bar and ha ha he
-skafjds bar and ha ha ha
-hello ha ha ha
-foob and ha ha ha
-skafjds bar and ha ha ha
-fjds bar and ha ha ha
-a b c and ha ha ha
-
-var foo = SomeBigName(arg1, arg2, arg3)
-var bar = SomeBigName(arg1, arg2, arg3)
-var xyz = SomeBigName(arg1, arg2, arg3)
-var xdf = Som
-
-
-
-

lc.vim

@@ -1,51 +1,62 @@
 vim9script
 
-def GetMatch(base: string, line: string, add_base: bool): list<any>
-    var s = base
-    while stridx(line, s) == -1
+class Item
+    const len: number
+    const val: string
+endclass
+
+def GetLongestSuffix(hay: string, ndl: string): string
+    var s = ndl
+    var l = len(ndl)
+    while stridx(hay, s) == -1
         s = strpart(s, 1)
-        if strlen(s) == 0
-            return [0, ""] # vim ignores these
+        l = l - 1
+        if l == 0
+            return ""
         endif
     endwhile
+    return s
+enddef
+# echo GetLongestSuffix("hello world", "world")->assert_equal("world")
+# echo GetLongestSuffix("hello world", "foo world")->assert_equal("o world")
+# echo GetLongestSuffix("hello world foo bar blah", "foo world")->assert_equal("o world")
+# echo v:errors
+
+def GetMatch(base: string, line: string, add_base: bool): Item
+    const s = GetLongestSuffix(line, base)
     const idx = stridx(line, s)
     const slen = strlen(s)
+    const  m = strpart(line, idx + slen)
     if add_base
-        return [slen, base .. strpart(line, idx + slen)]
-    else
-        return [slen, strpart(line, idx + slen)]
+        return Item.new(slen, base .. m)
     endif
+    return Item.new(slen, m)
+enddef
+
+def GetMatches(base: string, add_base: bool): list<string>
+    return getbufinfo()
+        ->filter( (_, bf) => bf.listed )
+        ->map( (_, buf) => getbufline(buf["bufnr"], 1, "$"))
+        ->flattennew()
+        ->sort()
+        ->uniq()
+        ->map( (_, v) => GetMatch(base, v, add_base) )
+        ->filter( (_, m) => m.len > 3 )
+        ->sort( (x, y) => y.len - x.len )
+        ->map( (_, m) => m.val )
 enddef
 
 def LineSuffixCompl(findstart: bool, base: string): any
     if findstart
         return 0
     endif
-    return  getbufinfo()
-        ->map( (_, buf) => getbufline(buf["bufnr"], 1, "$"))
-        ->flattennew()
-        ->sort()
-        ->uniq()
-        ->map( (_, v) => GetMatch(base, v, v:true) )
-        ->sort( (x, y) => y[0] - x[0] )
-        ->map( (_, v) => v[1] )
+    return GetMatches(base, true)
 enddef
 
-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 ''
+def DoLSCmpl()
+    GetMatches(getline('.'), false)->complete(col('.'))
 enddef
 
-# inoremap <C-X><C-L> <C-R>=<SID>DoLSCmpl()<CR>
+inoremap <C-X><C-L> <C-R>=<SID>DoLSCmpl()<CR>
 
 set completefunc=LineSuffixCompl