Merge pull request #1172 from geraldus/g/non-interactive-completions

Support simple completions in non-interactive context.  Support keyword completions

Author: gracjan

haskell-completions.el

@@ -1,6 +1,6 @@
 ;;; haskell-completions.el --- Haskell Completion package -*- lexical-binding: t -*-
 
-;; Copyright © 2015 Athur Fayzrakhmanov. All rights reserved.
+;; Copyright © 2015-2016 Athur Fayzrakhmanov. All rights reserved.
 
 ;; This file is part of haskell-mode package.
 ;; You can contact with authors using GitHub issue tracker:
@@ -40,7 +40,7 @@
 (require 'haskell-process)
 (require 'haskell-interactive-mode)
 
-(defvar haskell-completions-pragma-names
+(defvar haskell-completions--pragma-names
   (list "DEPRECATED"
         "INCLUDE"
         "INCOHERENT"
@@ -63,8 +63,51 @@
         "WARNING")
   "A list of supported pragmas.
 This list comes from GHC documentation (URL
-`https://downloads.haskell.org/~ghc/7.10.1/docs/html/users_guide/pragmas.html'.
-")
+`https://downloads.haskell.org/~ghc/7.10.1/docs/html/users_guide/pragmas.html'.")
+
+(defvar haskell-completions--keywords
+  (list
+   "as"
+   "case"
+   "class"
+   "data family"
+   "data instance"
+   "data"
+   "default"
+   "deriving instance"
+   "deriving"
+   "do"
+   "else"
+   "family"
+   "forall"
+   "foreign import"
+   "foreign"
+   "hiding"
+   "if"
+   "import qualified"
+   "import"
+   "in"
+   "infix"
+   "infixl"
+   "infixr"
+   "instance"
+   "let"
+   "mdo"
+   "module"
+   "newtype"
+   "of"
+   "proc"
+   "qualified"
+   "rec"
+   "then"
+   "type family"
+   "type instance"
+   "type"
+   "where")
+  "A list of Haskell's keywords (URL `https://wiki.haskell.org/Keywords').
+Single char keywords and operator like keywords are not included
+in this list.")
+
 
 (defun haskell-completions-can-grab-prefix ()
   "Check if the case is appropriate for grabbing completion prefix.
@@ -206,9 +249,20 @@ identifier at point depending on result of function
 Returns a list of form '(prefix-start-position
 prefix-end-position prefix-value prefix-type) depending on
 situation, e.g. is it needed to complete pragma, module name,
-arbitrary identifier, etc. Returns nil in case it is
+arbitrary identifier, etc.  Returns nil in case it is
 impossible to grab prefix.
 
+Possible prefix types are:
+
+* haskell-completions-pragma-name-prefix
+* haskell-completions-ghc-option-prefix
+* haskell-completions-language-extension-prefix
+* haskell-completions-module-name-prefix
+* haskell-completions-identifier-prefix
+* haskell-completions-general-prefix
+
+the last type is used in cases when completing things inside comments.
+
 If provided optional MINLEN parameter this function will return
 result only if prefix length is not less than MINLEN."
    (when (haskell-completions-can-grab-prefix)
@@ -220,36 +274,77 @@ result only if prefix length is not less than MINLEN."
                 prefix))
              (prefix prefix)))))
 
+(defun haskell-completions--simple-completions (prefix)
+  "Provide a list of completion candidates for given PREFIX.
+This function is used internally in
+`haskell-completions-completion-at-point' and
+`haskell-completions-sync-repl-completion-at-point'.
+
+It provides completions for haskell keywords, language pragmas,
+GHC's options, and language extensions.
+
+PREFIX should be a list such one returned by
+`haskell-completions-grab-identifier-prefix'."
+  (cl-destructuring-bind (beg end _pfx typ) prefix
+    (let ((candidates
+           (cl-case typ
+             ('haskell-completions-pragma-name-prefix
+              haskell-completions--pragma-names)
+             ('haskell-completions-ghc-option-prefix
+              haskell-ghc-supported-options)
+             ('haskell-completions-language-extension-prefix
+              haskell-ghc-supported-extensions)
+             (otherwise
+              haskell-completions--keywords))))
+      (list beg end candidates))))
+
+
+(defun haskell-completions-completion-at-point ()
+  "Provide completion list for thing at point.
+This function is used in non-interactive `haskell-mode'.  It
+provides completions for haskell keywords, language pragmas,
+GHC's options, and language extensions, but not identifiers."
+  (let ((prefix (haskell-completions-grab-prefix)))
+    (haskell-completions--simple-completions prefix)))
+
+(defun haskell-completions-sync-repl-completion-at-point ()
+  "A completion function used in `interactive-haskell-mode'.
+Completion candidates are provided quering current haskell
+process, that is sending `:complete repl' command.
+
+Completes all possible things: everything that can be completed
+with non-interactive function
+`haskell-completions-completion-at-point' plus identifier
+completions.
 
-(defun haskell-completions-sync-completions-at-point ()
-  "A `completion-at-point' function using the current haskell process.
 Returns nil if no completions available."
   (let ((prefix-data (haskell-completions-grab-prefix)))
     (when prefix-data
       (cl-destructuring-bind (beg end pfx typ) prefix-data
-        (let ((imp (eql typ 'haskell-completions-module-name-prefix))
-              lst)
-          (setq lst
-                (cl-case typ
-                  ;; non-interactive completions first
-                  ('haskell-completions-pragma-name-prefix
-                   haskell-completions-pragma-names)
-                  ('haskell-completions-ghc-option-prefix
-                   haskell-ghc-supported-options)
-                  ('haskell-completions-language-extension-prefix
-                   haskell-ghc-supported-extensions)
-                  (otherwise
-                   (when (and
-                          (not (eql typ 'haskell-completions-general-prefix))
-                          (haskell-session-maybe)
-                          (not
-                           (haskell-process-cmd (haskell-interactive-process))))
-                     ;; if REPL is available and not busy try to query it
-                     ;; for completions list in case of module name or
-                     ;; identifier prefixes
-                     (haskell-completions-sync-complete-repl pfx imp)))))
-          (when lst
-            (list beg end lst)))))))
+        (when (not (eql typ 'haskell-completions-general-prefix))
+          ;; do not complete things in comments
+          (if (cl-member
+               typ
+               '(haskell-completions-pragma-name-prefix
+                 haskell-completions-ghc-option-prefix
+                 haskell-completions-language-extension-prefix))
+              ;; provide simple completions
+              (haskell-completions--simple-completions prefix-data)
+            ;; only two cases left: haskell-completions-module-name-prefix
+            ;; and haskell-completions-identifier-prefix
+            (let* ((is-import (eql typ 'haskell-completions-module-name-prefix))
+                   (candidates
+                    (when (and (haskell-session-maybe)
+                               (not (haskell-process-cmd
+                                     (haskell-interactive-process))))
+                      ;; if REPL is available and not busy try to query it for
+                      ;; completions list in case of module name or identifier
+                      ;; prefixes
+                      (haskell-completions-sync-complete-repl pfx is-import))))
+              ;; append candidates with keywords
+              (list beg end (append
+                             candidates
+                             haskell-completions--keywords)))))))))
 
 (defun haskell-completions-sync-complete-repl (prefix &optional import)
   "Return completion list for given PREFIX querying REPL synchronously.

haskell-interactive-mode.el

@@ -1016,7 +1016,8 @@ don't care when the thing completes as long as it's soonish."
       (remove-overlays))))
 
 (defun haskell-interactive-mode-completion-at-point-function ()
-  "Offer completions for partial expression between prompt and point"
+  "Offer completions for partial expression between prompt and point.
+This completion function is used in interactive REPL buffer itself."
   (when (haskell-interactive-at-prompt)
     (let* ((process (haskell-interactive-process))
            (inp (haskell-interactive-mode-input-partial))

haskell-mode.el

@@ -783,6 +783,11 @@ Minor modes that work well with `haskell-mode':
   (setq haskell-literate nil)
   (add-hook 'before-save-hook 'haskell-mode-before-save-handler nil t)
   (add-hook 'after-save-hook 'haskell-mode-after-save-handler nil t)
+  ;; provide non-interactive completion function
+  (add-hook 'completion-at-point-functions
+            #'haskell-completions-completion-at-point
+            nil
+            t)
   (haskell-indentation-mode))
 
 (defun haskell-fill-paragraph (justify)

haskell.el

@@ -67,12 +67,12 @@
   :lighter " Interactive"
   :keymap interactive-haskell-mode-map
   (add-hook 'completion-at-point-functions
-            #'haskell-completions-sync-completions-at-point
+            #'haskell-completions-sync-repl-completion-at-point
             nil
             t))
 
 (make-obsolete 'haskell-process-completions-at-point
-               'haskell-completions-sync-completions-at-point
+               'haskell-completions-sync-repl-completion-at-point
                "June 19, 2015")
 (defun haskell-process-completions-at-point ()
   "A completion-at-point function using the current haskell process."