feat: Add basic support for S-exp plists -> TOML conversion

Support added for scalars and lists.
Pending: tables, arrays of tables, etc.

README.org

@@ -960,26 +960,29 @@ contributors = [
                   :key2 "klm")])
 #+end_src
 **** TOML
+#+begin_src emacs-lisp :noweb yes :exports results :wrap src toml
+(tomelr-encode
+  <<p-list>>)
+#+end_src
+
+#+RESULTS:
 #+begin_src toml
-int = 123.0
+int = 123
 str = "abc"
 bool_false = false
 bool_true = true
-int_list = [1.0, 2.0, 3.0]
-str_list = ["a", "b", "c"]
-bool_list = [true, false, true, false]
-list_of_lists = [ [1.0, 2.0],
-                  [3.0, 4.0, 5.0] ]
-
+int_list = [ 1, 2, 3 ]
+str_list = [ "a", "b", "c" ]
+bool_list = [ true, false, true, false ]
+list_of_lists = [ [ 1, 2 ], [ 3, 4, 5 ] ]
 [map]
-  key1 = 123.0
+  key1 = 123
   key2 = "xyz"
-
 [[list_of_maps]]
-  key1 = 123.0
+  key1 = 123
   key2 = "xyz"
 [[list_of_maps]]
-  key1 = 567.0
+  key1 = 567
   key2 = "klm"
 #+end_src
 **** JSON Reference

test/all-tests.el

@@ -25,3 +25,4 @@
 (require 'tnil)
 (require 'tarray)
 (require 'ttable)
+(require 'tplist)

test/tplist.el

@@ -0,0 +1,56 @@
+;; -*- lexical-binding: t; -*-
+
+;; Authors: Kaushal Modi <kaushal.modi@gmail.com>
+
+;; This file is not part of GNU Emacs.
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; Test conversion of S-exp plists to TOML.
+
+;;; Code:
+(require 'tomelr)
+
+;;;; S-exp objects as plists
+(ert-deftest test-plist ()
+  (let ((inp '((:int 123
+                :remove_this_key  nil
+                :str "abc"
+                :bool_false :false
+                :bool_true t
+                :int_list (1 2 3)
+                :str_list ("a" "b" "c")
+                :bool_list (t :false t :false)
+                :list_of_lists [(1 2) (3 4 5)]
+                ;; TODO plist specification of TOML tables is not yet supported.
+                ;; :map (:key1 123
+                ;;       :key2 "xyz")
+                )))
+        (ref '("int = 123
+str = \"abc\"
+bool_false = false
+bool_true = true
+int_list = [ 1, 2, 3 ]
+str_list = [ \"a\", \"b\", \"c\" ]
+bool_list = [ true, false, true, false ]
+list_of_lists = [ [ 1, 2 ], [ 3, 4, 5 ] ]"))
+        out)
+    (dolist (el inp)
+      (push (tomelr-encode el) out))
+    (should (equal ref (nreverse out)))))
+
+
+(provide 'tplist)

tomelr.el

@@ -144,11 +144,12 @@ Return nil if KEYWORD is not recognized as a TOML keyword."
     (and keyword (insert keyword))))
 
 ;;;; Strings
-(defun tomelr--print-string (string &optional trim-init-chars)
+(defun tomelr--print-string (string &optional type)
   "Insert a TOML representation of STRING at point.
 
-If TRIM-INIT-CHARS is positive, those many initial characters
-of the STRING are not inserted.
+Optional TYPE arg gives more information about the input STRING.
+For example, if the string is the name of a TOML key, it will be
+set to `keyword'.
 
 Return the same STRING passed as input.  See
 `tomelr-encode-string' instead if you need a function that
@@ -160,6 +161,7 @@ returns the TOML representation as a string."
         (special-chars-re (rx (in ?\" ?\\ cntrl ?\u007F))) ;cntrl is same as (?\u0000 . ?\u001F)
         begin-q end-q)
     (cond
+     ((equal type 'keyword))
      ((string-match-p tomelr--date-time-regexp string)) ;RFC 3339 formatted date-time with offset
      ;; Use multi-line string quotation if the string contains a " char
      ;; or a newline - """STRING"""
@@ -185,7 +187,6 @@ returns the TOML representation as a string."
       (setq end-q begin-q)))
     (and begin-q (insert begin-q))
     (goto-char (prog1 (point) (princ string)))
-    (and trim-init-chars (delete-char trim-init-chars))
     (while (re-search-forward special-chars-re nil :noerror)
       (let ((char (preceding-char)))
         (delete-char -1)
@@ -210,9 +211,11 @@ Return nil if OBJECT cannot be encoded as a TOML string."
   (cond ((stringp object)
          ;; (message "[tomelr--print-stringlike DBG] %S is string" object)
          (tomelr--print-string object))
-        ((keywordp object)
+        ((keywordp object) ;Symbol beginning with `:', like `:some_key'
          ;; (message "[tomelr--print-stringlike DBG] %S is keyword" object)
-         (tomelr--print-string (symbol-name object) 1))
+         (tomelr--print-string
+          (string-trim-left (symbol-name object) ":")
+          'keyword))
         ((symbolp object)
          (let ((sym-name (symbol-name object)))
            ;; (message "[tomelr--print-stringlike DBG] %S is symbol, type = %S, depth = %d"