bug#58070: [PATCH] Add tamil99 input method

[Arun Isaac <arunisaac@systemreboot.net>]

* lisp/leim/quail/tamil99.el: New file.
* etc/NEWS: Mention new tamil99 input method.
---
 etc/NEWS                   |   3 +
 lisp/leim/quail/tamil99.el | 200 +++++++++++++++++++++++++++++++++++++
 2 files changed, 203 insertions(+)
 create mode 100644 lisp/leim/quail/tamil99.el

diff --git a/etc/NEWS b/etc/NEWS
index 3d1af8bd6f..bcdc991ea3 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1279,6 +1279,9 @@ The default input method for the Tamil language environment is now
 change the input method's translation rules, customize the user option
 'tamil-translation-rules'.
 
+---
+*** New tamil99 input method for the Tamil language
+
 \f
 * Changes in Specialized Modes and Packages in Emacs 29.1
 
diff --git a/lisp/leim/quail/tamil99.el b/lisp/leim/quail/tamil99.el
new file mode 100644
index 0000000000..780ef968ee
--- /dev/null
+++ b/lisp/leim/quail/tamil99.el
@@ -0,0 +1,200 @@
+;;; tamil99.el --- Quail package for the tamil99 input method -*- lexical-binding: t -*-
+
+;; Copyright (C) 2022 Free Software Foundation, Inc.
+;;
+;; Author: Arun Isaac <arunisaac@systemreboot.net>
+;; Keywords: multilingual, input method, Indian, Tamil
+
+;; This file is part of GNU Emacs.
+;;
+;; GNU Emacs 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.
+;;
+;; GNU Emacs 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 GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+;;
+;; Tamil99 is a keyboard layout and input method that is specifically
+;; designed for the Tamil language. Vowels and vowel modifiers are
+;; input with your left hand, and consonants are input with your right
+;; hand. See https://en.wikipedia.org/wiki/Tamil_99
+;;
+;; தமிழ்99 தமிழுக்கென்றே உருவாக்கப்பட்ட விசைப்பலகை அமைப்பும் உள்ளீட்டு முறையும்
+;; ஆகும். உயிர்களை இடக்கையுடனும் மெய்களை வலக்கையுடனும் தட்டச்சிடும்படி
+;; அமைக்கப்பட்டது. https://ta.wikipedia.org/wiki/%E0%AE%A4%E0%AE%AE%E0%AE%BF%E0%AE%B4%E0%AF%8D_99
+;; காண்க.
+;;
+;; Usage:
+;;
+;; Switch to the tamil99 input method using M-x set-input-method
+;; tamil99 RET and enjoy typing in Tamil!
+;;
+;; பயன்பாடு:
+;;
+;; tamil99 உள்ளீட்டு முறைக்கு மாற M-x set-input-method tamil99 RET கட்டளையை
+;; இயக்கித் தமிழில் தட்டச்சிட்டு மகிழ்க!
+
+;;; Code:
+
+(require 'pcase)
+(require 'quail)
+(require 'seq)
+
+(quail-define-package
+ "tamil99" "Tamil" "தமிழ்99"
+ t "Tamil99 input method"
+ nil t t t t nil nil nil nil nil t)
+
+(defconst tamil99-vowels
+  '(("q" "ஆ")
+    ("w" "ஈ")
+    ("e" "ஊ")
+    ("r" "ஐ")
+    ("t" "ஏ")
+    ("a" "அ")
+    ("s" "இ")
+    ("d" "உ")
+    ("g" "எ")
+    ("z" "ஔ")
+    ("x" "ஓ")
+    ("c" "ஒ"))
+  "Mapping for vowels.")
+
+(defconst tamil99-vowel-modifiers
+  '(("q" "ா")
+    ("w" "ீ")
+    ("e" "ூ")
+    ("r" "ை")
+    ("t" "ே")
+    ("a" "")
+    ("s" "ி")
+    ("d" "ு")
+    ("g" "ெ")
+    ("z" "ௌ")
+    ("x" "ோ")
+    ("c" "ொ")
+    ("f" "்"))
+  "Mapping for vowel modifiers.")
+
+(defconst tamil99-vallinam-consonants
+  '(("h" "க")
+    ("[" "ச")
+    ("o" "ட")
+    ("l" "த")
+    ("j" "ப")
+    ("u" "ற"))
+  "Mapping for vallinam consonants.")
+
+(defconst tamil99-mellinam-consonants
+  '(("b" "ங")
+    ("]" "ஞ")
+    ("p" "ண")
+    (";" "ந")
+    ("k" "ம")
+    ("i" "ன"))
+  "Mapping for mellinam consonants.")
+
+(defconst tamil99-idaiinam-consonants
+  '(("'" "ய")
+    ("m" "ர")
+    ("n" "ல")
+    ("v" "வ")
+    ("/" "ழ")
+    ("y" "ள"))
+  "Mapping for idaiinam consonants.")
+
+(defconst tamil99-grantham-consonants
+  '(("Q" "ஸ")
+    ("W" "ஷ")
+    ("E" "ஜ")
+    ("R" "ஹ"))
+  "Mapping for grantham consonants.")
+
+(defconst tamil99-consonants
+  (append tamil99-vallinam-consonants
+          tamil99-mellinam-consonants
+          tamil99-idaiinam-consonants
+          tamil99-grantham-consonants)
+  "Mapping for all consonants.")
+
+(defconst tamil99-other
+  `(("T" ,(vector "க்ஷ"))
+    ("Y" ,(vector "ஶஂரீ"))
+    ("O" "[")
+    ("P" "]")
+    ("A" "௹")
+    ("S" "௺")
+    ("D" "௸")
+    ("F" "ஃ")
+    ("K" "\"")
+    ("L" ":")
+    (":" ";")
+    ("\"" "'")
+    ("Z" "௳")
+    ("X" "௴")
+    ("C" "௵")
+    ("V" "௶")
+    ("B" "௷")
+    ("M" "/"))
+  "Mapping for miscellaneous characters.")
+
+(defun tamil99-install ()
+  "Install tamil99 input method."
+  (quail-define-rules)
+  ;; உயிர்
+  ;; vowel
+  (mapc (pcase-lambda (`(,vowel-key ,vowel))
+          (quail-defrule vowel-key vowel))
+        tamil99-vowels)
+  (mapc (pcase-lambda (`(,consonant-key ,consonant))
+          ;; அகர உயிர்மெய்
+          ;; consonant with agaram (அ)
+          (quail-defrule consonant-key consonant)
+          ;; மெய்யொற்று பின் அகர உயிர்மெய்
+          ;; pulli on double consonant
+          (quail-defrule (concat consonant-key consonant-key)
+                         (vector (concat consonant "்" consonant)))
+          (mapc (pcase-lambda (`(,vowel-key ,vowel-modifier))
+                  ;; உயிர்மெய்
+                  ;; vowel+consonant
+                  (quail-defrule (concat consonant-key vowel-key)
+                                 (vector (concat consonant vowel-modifier)))
+                  ;; மெய்யொற்று பின் உயிர்மெய்
+                  ;; vowel+consonant after double consonant
+                  (quail-defrule (concat consonant-key consonant-key vowel-key)
+                                 (vector (concat consonant "்" consonant vowel-modifier))))
+                tamil99-vowel-modifiers))
+        tamil99-consonants)
+  (seq-mapn (pcase-lambda (`(,mellinam-consonant-key ,mellinam-consonant)
+                           `(,vallinam-consonant-key ,vallinam-consonant))
+              ;; மெல்லினம் பின் வல்லினம்
+              ;; vallinam after mellinam
+              (quail-defrule (concat mellinam-consonant-key vallinam-consonant-key)
+                             (vector (concat mellinam-consonant "்" vallinam-consonant)))
+              (mapc (pcase-lambda (`(,vowel-key ,vowel-modifier))
+                      ;; மெல்லின ஒற்றொட்டிய வல்லினம் பின் உயிர்மெய்
+                      ;; vowel+consonant after mellinam-vallinam consonant
+                      (quail-defrule (concat mellinam-consonant-key vallinam-consonant-key vowel-key)
+                                     (vector (concat mellinam-consonant "்" vallinam-consonant vowel-modifier))))
+                    tamil99-vowel-modifiers))
+            tamil99-mellinam-consonants
+            tamil99-vallinam-consonants)
+  ;; பிற வரியுருக்கள்
+  ;; other characters
+  (mapc (pcase-lambda (`(,key ,translation))
+          (quail-defrule key translation))
+        tamil99-other))
+
+(tamil99-install)
+
+(provide 'tamil99)
+
+;;; tamil99.el ends here
-- 
2.37.2