Support shiftwidth=0 in indent and fold

With shiftwidth=0, Vim uses the value of tabstop, but &sw is 0. So
multiline tags and brackets got wrong indent, and fold levels were wrong
as indent was divided by 0. Use shiftwidth() instead, which is the same
as &sw when it isn't 0.

ftplugin/vue/fold.vim

@@ -88,7 +88,7 @@ endfunction
 
 function! s:IndentLevel(lnum)
   " Add 1 to indentLevel, so start/end tags can fold properly
-  return indent(a:lnum) / &shiftwidth + 1
+  return indent(a:lnum) / shiftwidth() + 1
 endfunction
 "}}}
 

indent/vue.vim

@@ -148,7 +148,7 @@ function! s:CheckInitialIndent(tag, syntax, ind)
   endif
   if add
     call vue#LogWithLnum('add initial indent')
-    let ind = &sw
+    let ind = shiftwidth()
   endif
   return ind
 endfunction
@@ -183,16 +183,16 @@ function! s:AdjustHTMLIndent(ind)
 
   if prevline =~? s:empty_tag
     call vue#LogWithLnum('previous line is an empty tag')
-    let ind = ind - &sw
+    let ind = ind - shiftwidth()
   endif
 
   " Align '/>' and '>' with '<'
   if curline =~? s:tag_end 
-    let ind = ind - &sw
+    let ind = ind - shiftwidth()
   endif
   " Then correct the indentation of any element following '/>' or '>'.
   if prevline =~? s:tag_end
-    let ind = ind + &sw
+    let ind = ind + shiftwidth()
 
     " Decrease indent if prevlines are a multiline empty tag
     let [start, end] = s:PrevMultilineEmptyTag(v:lnum)
@@ -200,7 +200,7 @@ function! s:AdjustHTMLIndent(ind)
       call vue#LogWithLnum('previous line is a multiline empty tag')
       let ind = indent(v:lnum - 1)
       if curline =~? s:full_tag_end 
-        let ind = ind - &sw
+        let ind = ind - shiftwidth()
       endif
     endif
   endif
@@ -210,17 +210,17 @@ function! s:AdjustHTMLIndent(ind)
   " ]
   if prevline =~ '[[{]\s*$'
     call vue#LogWithLnum('previous line is an open bracket')
-    let ind = indent(prevlnum) + &sw
+    let ind = indent(prevlnum) + shiftwidth()
   endif
   if curline =~ '^\s*[]}][^"]*"\?\s*$'
     call vue#LogWithLnum('current line is a closing bracket')
-    let ind = indent(prevlnum) - &sw
+    let ind = indent(prevlnum) - shiftwidth()
   endif
 
   " Multiline ternary 'a ? b : c' in attribute
   if curline =~ s:ternary_q
     call vue#LogWithLnum('current line is ?...')
-    let ind = indent(prevlnum) + &sw
+    let ind = indent(prevlnum) + shiftwidth()
   endif
   if curline =~ s:ternary_e && prevline =~ s:ternary_q
     call vue#LogWithLnum('current line is :...')
@@ -228,13 +228,13 @@ function! s:AdjustHTMLIndent(ind)
   endif
   if prevline =~ s:ternary_e
     call vue#LogWithLnum('prevline line is :...')
-    let ind = indent(prevlnum) - &sw
+    let ind = indent(prevlnum) - shiftwidth()
   endif
 
   " Angle bracket in attribute, like v-if="isEnabled('item.<name>')"
   if prevline =~ '="[^"]*<[^"]*>[^"]*"'
     call vue#LogWithLnum('prevline line is angle bracket in attribute')
-    let ind = ind - &sw
+    let ind = ind - shiftwidth()
   endif
 
   return ind
@@ -248,7 +248,7 @@ function! s:AdjustJavaScriptIndent(ind)
 
   if prevline =~ '^\s*\w.*$' && curline =~ '^\s*\.'
     call vue#LogWithLnum('current line is the first chain call')
-    let ind = indent(prevlnum) + &sw
+    let ind = indent(prevlnum) + shiftwidth()
   endif
 
   if prevline =~ '\s=>\s.*,\s*$' && curline !~ '^\s*[]}])\?,\?\s*$'
@@ -257,7 +257,7 @@ function! s:AdjustJavaScriptIndent(ind)
   endif
   if prevline =~ '\s||\s*$'
     call vue#LogWithLnum('previous line ends with "||"')
-    let ind = indent(prevlnum) + &sw
+    let ind = indent(prevlnum) + shiftwidth()
   endif
   return ind
 endfunction
@@ -270,11 +270,11 @@ function! s:AdjustCSSIndent(ind)
 
   if prevline =~ ':\s.*,\s*$'
     call vue#LogWithLnum('previous line is css function')
-    let ind = indent(prevlnum) + &sw
+    let ind = indent(prevlnum) + shiftwidth()
   endif
   if curline =~ '^\s*);\?\s*$'
     call vue#LogWithLnum('curline is closing round bracket')
-    let ind = indent(prevlnum) - &sw
+    let ind = indent(prevlnum) - shiftwidth()
   endif
   return ind
 endfunction

test/cases/shiftwidth-zero.vim

@@ -0,0 +1,11 @@
+" shiftwidth=0 uses the value of tabstop, same as shiftwidth=4 here
+set shiftwidth=0 tabstop=4
+let g:vim_vue_plugin_config = {'foldexpr': 1}
+let g:test_flatten = 1
+
+function! Check()
+  let levels = [1, 2, 3, 2, 3, 4, 3, 3, 2, 1]
+  for lnum in range(1, len(levels))
+    call ExpectFoldlevel(lnum, levels[lnum - 1])
+  endfor
+endfunction

test/cases/shiftwidth-zero.vue

@@ -0,0 +1,24 @@
+<template>
+    <div
+        class="a"
+    >
+        <input
+            type="text"
+        >
+        <p :class="{ a: b }">x</p>
+    </div>
+</template>
+
+<script>
+export default {
+    data() {
+        return { a: 1 }
+    },
+}
+</script>
+
+<style>
+p {
+    color: red;
+}
+</style>