(feature): Support accessing snippets for all modes

Closes #4

+ Make consult-yasnippet read the template in the function body, instead
  of the interactive statement.
+ Change the function signature of consult-yasnippet to an optional
  argument that triggers the reading of snippets from all snippet
  tables.
+ Add consult-yasnippet--annotate, which suffixes each candidate with
  name of the snippet table it came from.

consult-yasnippet.el

@@ -27,6 +27,7 @@
 
 ;;; Code:
 
+(require 'map)
 (require 'consult)
 (require 'yasnippet)
 
@@ -89,25 +90,39 @@ the state of the current buffer to before any snippets were previewed."
                 (setcdr region (- (point-max) orig-offset))))
             (redisplay)))))))
 
-(defun consult-yasnippet--candidates ()
-  "Retrieve the list of available snippets in the current buffer."
-  (unless (bound-and-true-p yas-minor-mode)
-    (error "`yas-minor-mode' not enabled in current buffer"))
-
+(defun consult-yasnippet--candidates (templates &optional include-table)
+  "Convert TEMPLATES into candidates for completing-read.
+If TEMPLATES is ommitted, it defaults to all the available
+templates in the current buffer. When INCLUDE-TABLE is non-nil
+then each candidate string will be prefixed with the snippet
+table."
   (mapcar
    (lambda (template)
-     (cons (concat (yas--template-name template)
-                   (concat
-                    " ["
-                    (propertize (or (yas--template-key template)
-                                    (and (functionp 'yas--template-regexp-key)
-                                         (yas--template-regexp-key template)))
-                                'face 'consult-key)
-                    "]"))
+     (cons (concat
+            (when include-table
+              (propertize (concat (yas--table-name (yas--template-table template))
+                                  " ")
+                          'invisible t))
+            (yas--template-name template)
+            " ["
+            (propertize (or (yas--template-key template)
+                            (and (functionp 'yas--template-regexp-key)
+                                 (yas--template-regexp-key template)))
+                        'face 'consult-key)
+            "]")
            template))
-   (yas--all-templates (yas--get-snippet-tables))))
-
-(defun consult-yasnippet--read-template ()
+   templates))
+
+(defun consult-yasnippet--annotate (candidates)
+  (lambda (cand)
+    (when-let ((template (cdr (assoc cand candidates)))
+               (table-name (yas--table-name (yas--template-table template))))
+      (concat
+       " "
+       (propertize " " 'display `(space :align-to (- right ,(+ 1 (length table-name)))))
+       table-name))))
+
+(defun consult-yasnippet--read-template (&optional all-templates)
   "Backend implementation of `consult-yasnippet'.
 
 This starts a `completing-read' session with all the snippets in the current
@@ -116,12 +131,22 @@ replacing the active region with the snippet expansion.
 
 This function doesn't actually expand the snippet, it only reads and then
 returns a snippet template from the user."
+  (unless (bound-and-true-p yas-minor-mode)
+    (error "`consult-yasnippet' can only be called while `yas-minor-mode' is active"))
+
   (barf-if-buffer-read-only)
 
-  (let* ((buffer-undo-list t))                                                  ; Prevent querying user (and showing previews) from updating the undo-history
+  (let* ((buffer-undo-list t)                                                  ; Prevent querying user (and showing previews) from updating the undo-history
+         (candidates
+          (consult-yasnippet--candidates
+           (if all-templates
+               (yas--all-templates (map-values yas--tables))
+             (yas--all-templates (yas--get-snippet-tables)))
+           all-templates)))
     (consult--read
-     (consult-yasnippet--candidates)
+     candidates
      :prompt "Choose a snippet: "
+     :annotate (consult-yasnippet--annotate candidates)
      :lookup 'consult--lookup-cdr
      :require-match t
      :state (consult-yasnippet--preview)
@@ -137,16 +162,19 @@ using `yas--visit-snippet-file-1'."
   (yas--visit-snippet-file-1 template))
 
 ;;;###autoload
-(defun consult-yasnippet (template)
+(defun consult-yasnippet (&optional all-templates)
   "Interactively select and expand the yasnippet template TEMPLATE.
 When called interactively this command presents a completing read interface
 containing all currently available snippet expansions, with live previews for
 each snippet. Once selected a chosen snippet will be expanded at point using
-`yas-expand-snippet'."
-  (interactive (list (consult-yasnippet--read-template)))
-  (yas-expand-snippet (yas--template-content template)
-                      nil nil
-                      (yas--template-expand-env template)))
+`yas-expand-snippet'.
+
+With ARG select snippets from all snippet tables, not just the current one."
+  (interactive "P")
+  (when-let ((template (consult-yasnippet--read-template all-templates)))
+    (yas-expand-snippet (yas--template-content template)
+                        nil nil
+                        (yas--template-expand-env template))))
 
 (provide 'consult-yasnippet)
 ;;; consult-yasnippet.el ends here