First pass at optimizing ale to autoload (#80)

* First pass at optimizing ale to autoload

First off, the structure/function names should be revised a bit,
but I will wait for @w0rp's input before unifying the naming style.
Second off, the docs probably need some more work, I just did some
simple find-and-replace work.

With that said, this pull brings major performance gains for ale. On my
slowest system, fully loading ale and all its code takes around 150ms.

I have moved all of ale's autoload-able code to autoload/, and in
addition, implemented lazy-loading of linters. This brings load time on
that same system down to 5ms.

The only downside of lazy loading is that `g:ale_linters` cannot be
changed at runtime; however, it also speeds up performance at runtime by
simplfying the logic greatly.

Please let me know what you think!

Closes #59

* Address Travis/Vint errors

For some reason, ale isn't running vint for me...

* Incorporate feedback, make fixes

Lazy-loading logic is much improved.

* Add header comments; remove incorrect workaround

* Remove unneeded plugin guards

* Fix lazy-loading linter logic

Set the wrong variable....

* Fix capitialization

1 files changed, 48 insertions, 0 deletions

diff --git a/autoload/ale.vim b/autoload/ale.vim
new file mode 100644
index 00000000..b25bcc99
--- /dev/null
+++ b/autoload/ale.vim
@@ -0,0 +1,48 @@
+" Author: w0rp <devw0rp@gmail.com>
+" Description: Primary code path for the plugin
+"   Manages execution of linters when requested by autocommands
+
+let s:lint_timer = -1
+
+function! ale#Queue(delay) abort
+    if s:lint_timer != -1
+        call timer_stop(s:lint_timer)
+        let s:lint_timer = -1
+    endif
+
+    let linters = ale#linter#Get(&filetype)
+    if len(linters) == 0
+        " There are no linters to lint with, so stop here.
+        return
+    endif
+
+    if a:delay > 0
+        let s:lint_timer = timer_start(a:delay, function('ale#Lint'))
+    else
+        call ale#Lint()
+    endif
+endfunction
+
+function! ale#Lint(...) abort
+    let buffer = bufnr('%')
+    let linters = ale#linter#Get(&filetype)
+
+    " Set a variable telling us to clear the loclist later.
+    let g:ale_buffer_should_reset_map[buffer] = 1
+
+    for linter in linters
+        " Check if a given linter has a program which can be executed.
+        if has_key(linter, 'executable_callback')
+            let l:executable = ale#util#GetFunction(linter.executable_callback)(buffer)
+        else
+            let l:executable = linter.executable
+        endif
+
+        if !executable(l:executable)
+            " The linter's program cannot be executed, so skip it.
+            continue
+        endif
+
+        call ale#engine#Invoke(buffer, linter)
+    endfor
+endfunction