Support for :perl, :perlfile, :perldo and perleval() (#12809)

* support for :perl, :perlfile, :perldo and perleval()

* document that the perl provider doesn't currently work on Windows

* document that the perl legacy interface is now also supported

* added perleval() documentation

* import legacy perl interface tests

* only perl 5.22+ is supported

* healtcheck: use g:perl_host_prog if its set instead

using just 'perl' isn't correct as it may not be the version requested.
ditto for 'cpanm', rather go through 'App::cpanminus' to find the latest
perl version

test/functional/helpers.lua

@@ -768,9 +768,12 @@ function module.new_pipename()
 end
 
 function module.missing_provider(provider)
-  if provider == 'ruby' or provider == 'node' or provider == 'perl' then
+  if provider == 'ruby' or provider == 'node' then
     local prog = module.funcs['provider#' .. provider .. '#Detect']()
     return prog == '' and (provider .. ' not detected') or false
+  elseif provider == 'perl' then
+    local errors = module.funcs['provider#'..provider..'#Detect']()[2]
+    return errors ~= '' and errors or false
   elseif provider == 'python' or provider == 'python3' then
     local py_major_version = (provider == 'python3' and 3 or 2)
     local errors = module.funcs['provider#pythonx#Detect'](py_major_version)[2]

test/functional/provider/perl_spec.lua

@@ -5,6 +5,10 @@ local command = helpers.command
 local write_file = helpers.write_file
 local eval = helpers.eval
 local retry = helpers.retry
+local curbufmeths = helpers.curbufmeths
+local insert = helpers.insert
+local expect = helpers.expect
+local feed = helpers.feed
 
 do
   clear()
@@ -19,7 +23,51 @@ before_each(function()
   clear()
 end)
 
-describe('perl host', function()
+describe('legacy perl provider', function()
+  if helpers.pending_win32(pending) then return end
+
+  it('feature test', function()
+    eq(1, eval('has("perl")'))
+  end)
+
+  it(':perl command', function()
+    command('perl $vim->vars->{set_by_perl} = [100, 0];')
+    eq({100, 0}, eval('g:set_by_perl'))
+  end)
+
+  it(':perlfile command', function()
+    local fname = 'perlfile.pl'
+    write_file(fname, '$vim->command("let set_by_perlfile = 123")')
+    command('perlfile perlfile.pl')
+    eq(123, eval('g:set_by_perlfile'))
+    os.remove(fname)
+  end)
+
+  it(':perldo command', function()
+    -- :perldo 1; doesn't change $_,
+    -- the buffer should not be changed
+    command('normal :perldo 1;')
+    eq(false, curbufmeths.get_option('modified'))
+    -- insert some text
+    insert('abc\ndef\nghi')
+    expect([[
+      abc
+      def
+      ghi]])
+    -- go to top and select and replace the first two lines
+    feed('ggvj:perldo $_ = reverse ($_)."$linenr"<CR>')
+    expect([[
+      cba1
+      fed2
+      ghi]])
+  end)
+
+  it('perleval()', function()
+    eq({1, 2, {['key'] = 'val'}}, eval([[perleval('[1, 2, {"key" => "val"}]')]]))
+  end)
+end)
+
+describe('perl provider', function()
   if helpers.pending_win32(pending) then return end
   teardown(function ()
     os.remove('Xtest-perl-hello.pl')