bug#58070: [PATCH v2] Add tamil99 input method

[Arun Isaac]

* lisp/leim/quail/indian.el: Require pcase and seq.
("tamil99"): New input method.
* etc/NEWS: Mention new tamil99 input method.
---
 etc/NEWS                  |   3 +
 lisp/leim/quail/indian.el | 161 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 164 insertions(+)

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
+
 
 * Changes in Specialized Modes and Packages in Emacs 29.1
 
diff --git a/lisp/leim/quail/indian.el b/lisp/leim/quail/indian.el
index 431d8369c1..30b521e389 100644
--- a/lisp/leim/quail/indian.el
+++ b/lisp/leim/quail/indian.el
@@ -30,6 +30,8 @@
 
 ;;; Code:
 
+(require 'pcase)
+(require 'seq)
 (require 'quail)
 (require 'ind-util)
 
@@ -699,6 +701,165 @@ is."
  "tamil-inscript-digits" "Tamil" "TmlISD"
  "Tamil keyboard Inscript with Tamil digits support.")
 
+;; Tamil99 input method
+;;
+;; 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 உள்ளீட்டு முறை
+;;
+;; 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.
+
+(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.")
+
+;; 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)
+
 ;; Probhat Input Method
 (quail-define-package
  "bengali-probhat" "Bengali" "BngPB" t
-- 
2.37.3