Add jsonnet support, closes #515

autoload/jsonnet.vim

@@ -0,0 +1,129 @@
+if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'jsonnet') == -1
+
+
+
+" Options.
+
+if !exists("g:jsonnet_command")
+  let g:jsonnet_command = "jsonnet"
+endif
+
+if !exists("g:jsonnet_fmt_command")
+  let g:jsonnet_fmt_command = "jsonnetfmt"
+endif
+
+if !exists('g:jsonnet_fmt_options')
+  let g:jsonnet_fmt_options = ''
+endif
+
+if !exists('g:jsonnet_fmt_fail_silently')
+  let g:jsonnet_fmt_fail_silently = 1
+endif
+
+
+" System runs a shell command. It will reset the shell to /bin/sh for Unix-like
+" systems if it is executable.
+function! jsonnet#System(str, ...)
+  let l:shell = &shell
+  if executable('/bin/sh')
+    let &shell = '/bin/sh'
+  endif
+
+  try
+    let l:output = call("system", [a:str] + a:000)
+    return l:output
+  finally
+    let &shell = l:shell
+  endtry
+endfunction
+
+
+" CheckBinPath checks whether the given binary exists or not and returns the
+" path of the binary. It returns an empty string if it doesn't exists.
+function! jsonnet#CheckBinPath(binName)
+
+    if executable(a:binName)
+        if exists('*exepath')
+            let binPath = exepath(a:binName)
+	    return binPath
+        else
+	   return a:binName
+        endif
+    else
+        echo "vim-jsonnet: could not find '" . a:binName . "'."
+        return ""
+    endif
+
+endfunction
+
+" Format calls `jsonnetfmt ... ` on the file and replaces the file with the
+" auto formatted version. Does some primitive error checking of the
+" jsonnetfmt command too.
+function! jsonnet#Format()
+
+    " Save cursor position and many other things.
+    let l:curw = winsaveview()
+
+    " Write current unsaved buffer to a temp file
+    let l:tmpname = tempname()
+    call writefile(getline(1, '$'), l:tmpname)
+
+    " get the command first so we can test it
+    let l:binName = g:jsonnet_fmt_command
+
+   " check if the user has installed command binary.
+    let l:binPath = jsonnet#CheckBinPath(l:binName)
+    if empty(l:binPath)
+      return
+    endif
+
+
+    " Populate the final command.
+    let l:command = l:binPath
+    " The inplace modification is default. Makes file management easier
+    let l:command = l:command . ' -i '
+    let l:command = l:command . g:jsonnet_fmt_options
+
+    " Execute the compiled jsonnetfmt command and save the return value
+    let l:out = jsonnet#System(l:command . " " . l:tmpname)
+    let l:errorCode = v:shell_error
+
+    if l:errorCode == 0
+        " The format command succeeded Move the formatted temp file over the
+        " current file and restore other settings
+
+        " stop undo recording
+        try | silent undojoin | catch | endtry
+
+        let l:originalFileFormat = &fileformat
+        if exists("*getfperm")
+          " save old file permissions
+          let l:originalFPerm = getfperm(expand('%'))
+        endif
+        " Overwrite current file with the formatted temp file
+        call rename(l:tmpname, expand('%'))
+
+        if exists("*setfperm") && l:originalFPerm != ''
+          call setfperm(expand('%'), l:originalFPerm)
+        endif
+        " the file has been changed outside of vim, enable reedit
+        silent edit!
+        let &fileformat = l:originalFileFormat
+        let &syntax = &syntax
+    elseif g:jsonnet_fmt_fail_silently == 0
+        " FixMe: We could leverage the errors coming from the `jsonnetfmt` and
+        " give immediate feedback to the user at every save time.
+        " Our inspiration, vim-go, opens a new list below the current edit
+        " window and shows the errors (the output of the fmt command).
+        " We are not sure whether this is desired in the vim-jsonnet community
+        " or not. Nevertheless, this else block is a suitable place to benefit
+        " from the `jsonnetfmt` errors.
+    endif
+
+    " Restore our cursor/windows positions.
+    call winrestview(l:curw)
+endfunction
+
+
+
+endif