Use the minimum available ID

Fixes #309

CHANGELOG.md

@@ -1,3 +1,6 @@
+### 30/11/2020
+  - Change the next id calculation to use the minimum available value.
+    ([\#309](https://github.com/kassio/neoterm/issues/309))
 ### 05/11/2020
   - Better exception handling when toggling neoterm and it's the last open
     window.

autoload/neoterm.vim

@@ -319,3 +319,19 @@ function! s:resize_instance(instance) abort
     exec printf('%s resize %s', a:instance.mod, size)
   endif
 endfunction
+
+" Calculates the next neoterm's ID.
+" Returns the minimum next available id, an id not related
+" to an neoterm instance.
+function! neoterm#next_id(instances, last_id)
+  let l:instance_ids = map(keys(a:instances), {_, v -> str2nr(v) })
+
+  for i in range(1, max(l:instance_ids) + 1)
+    if index(l:instance_ids, i) < 0
+      let l:last_id = i
+      return l:last_id
+    end
+  endfor
+
+  return a:last_id + 1
+endfunction

doc/neoterm.txt

@@ -39,8 +39,8 @@ Commands lacking a prefix will always be executed in the last active neoterm.
 
 1.4 ID calculation                                      *neoterm-id-calculation*
 
-The ID is a sequential number starting from 1. To avoid big ID numbers, the ID
-is reseted to 1 when there is no instance of a neoterm windows open.
+The ID is a numeric value. It's calculates the minimum available value,
+starting from 1.
 
 1.4 Last Active                                            *neoterm-last-active*
 

plugin/neoterm.vim

@@ -12,18 +12,10 @@ let g:neoterm = {
       \ 'managed': []
       \ }
 
-" Calculates the next neoterm's ID.
-" The ID is a sequential number starting from 1.
-" To avoid big ID numbers, the ID is reseted to 1
-" when there is no instance of a neoterm windows open
 function! g:neoterm.next_id()
-  if len(keys(l:self.instances)) == 0
-    let l:self.last_id = 1
-    return l:self.last_id
-  else
-    let l:self.last_id += 1
-    return l:self.last_id
-  end
+  let l:self.last_id = neoterm#next_id(l:self.instances, l:self.last_id)
+
+  return l:self.last_id
 endfunction
 
 function! g:neoterm.has_any()

vmtest/neoterm.vim

@@ -0,0 +1,23 @@
+call vmtest#plugin('neoterm')
+let g:vmtests.neoterm.neoterm = { '_name': 'g:neoterm tests' }
+
+function! g:vmtests.neoterm.neoterm.test_when_theres_no_instances()
+  call assert_equal(
+        \ 1,
+        \ neoterm#next_id({}, 0)
+        \ )
+endfunction
+
+function! g:vmtests.neoterm.neoterm.test_when_theres_sequential_instances()
+  call assert_equal(
+        \ 4,
+        \ neoterm#next_id({'1': v:null, '2': v:null, '3': v:null}, 3)
+        \ )
+endfunction
+
+function! g:vmtests.neoterm.neoterm.test_when_instances_are_not_sequential()
+  call assert_equal(
+        \ 2,
+        \ neoterm#next_id({'1': v:null, '3': v:null}, 3)
+        \ )
+endfunction