fix zero origin base value

closes #420

autoload/emmet.vim

@@ -182,17 +182,9 @@ endfunction
 function! s:itemno(itemno, current) abort
   let current = a:current
   if current.basedirect > 0
-    if current.basevalue ==# 0
-      return a:itemno
-    else
-      return current.basevalue - 1 + a:itemno
-    endif
+    return current.basevalue - 1 + a:itemno
   else
-    if current.basevalue ==# 0
-      return current.multiplier - 1 - a:itemno
-    else
-      return current.multiplier + current.basevalue - 2 - a:itemno
-    endif
+    return current.multiplier + current.basevalue - 2 - a:itemno
   endif
 endfunction
 

autoload/emmet/lang/html.vim

@@ -154,7 +154,11 @@ function! emmet#lang#html#parseIntoTree(abbr, type) abort
     endif
 
     let basedirect = basevalue[1] ==# '-' ? -1 : 1
-    let basevalue = 0 + abs(basevalue[1:])
+    if basevalue != ''
+      let basevalue = 0 + abs(basevalue[1:])
+    else
+      let basevalue = 1
+    endif
     if multiplier <= 0 | let multiplier = 1 | endif
 
     " make default node

unittest.vim

@@ -679,6 +679,15 @@ finish
         },
       ],
     },
+    {
+      'name': 'base value',
+      'tests': [
+        {
+          'query': "ul>li#id$@0*3",
+          'result': "<ul>\n\t<li id=\"id0\"></li>\n\t<li id=\"id1\"></li>\n\t<li id=\"id2\"></li>\n</ul>\n",
+        },
+      ],
+    },
   ],
   'dummy': "}}}"},
 { 'test-css': '{{{',