Context-sensitive info index lookup with helm

mrc-helm-context-info.el

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;; helm info
(defvar mrc-helm-context-info-alist
  '(((emacs-lisp-mode lisp-interaction-mode inferior-emacs-lisp-mode)
     . (helm-source-info-elisp helm-source-info-cl helm-source-info-emacs))
    ((org-mode) . (helm-source-info-org))
    ((lisp-mode) . ((name . "Hyperspec") (info-index . "ansicl")
                    ((name . "Iterate") (info-index . "iterate")))))
  "Alist of modes to Helm sources.

Each element looks like (MODES . SOURCES). MODES is a list of
major modes. SOURCES is a list of helm sources.")

(defun mrc-helm-context-info ()
  (interactive)
  (let ((context (cdar (cl-remove-if-not (lambda (alist) (memq major-mode (car alist)))
                                         mrc-helm-context-info-alist))))
    (message "context: %S" context)
    (when context
      (helm :sources context :buffer "*helm-info-context*"))))

(global-set-key (kbd "C-h C-i") #'mrc-helm-context-info)