;; TELU-OTF.flt -- Font Layout Table for Telugu OpenType fonts
;; Copyright (C) 2004
;;   National Institute of Advanced Industrial Science and Technology (AIST)
;;   Registration Number H15PRO112

;; This file is part of the m17n database; a sub-part of the m17n
;; library.

;; The m17n library is free software; you can redistribute it and/or
;; modify it under the terms of the GNU Lesser General Public License
;; as published by the Free Software Foundation; either version 2.1 of
;; the License, or (at your option) any later version.

;; The m17n library 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
;; Lesser General Public License for more details.

;; You should have received a copy of the GNU Lesser General Public
;; License along with the m17n library; if not, write to the Free
;; Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
;; 02111-1307, USA.

;;; <li> TELU-OTF.flt
;;;
;;; For Telugu OpenType fonts to draw Telugu.
;;; Designed for Pothana2000.ttf <http://www.kavya-nandanam.com/>

(category
 ;; C: general consonant
 ;; R: no below-base consonat (RRA, NNNA, LLLA)
 ;; H: HALANT
 ;; u: MATRA (above)
 ;; b: MATRA (below)
 ;; p: MATRA (post)
 ;; t: MATRA (two-part)
 ;; a: vowel modifier (post)
 ;; V: independent vowel
 ;; N: ZWNJ (ZERO WIDTH NON-JOINER)
 ;; J: ZWJ (ZERO WIDTH JOINER)
 ;; E: ELSE
 ;;
 (0x200C	?N)			; ZWNJ
 (0x200D	?J)			; ZWJ
 (0x0964	?E)			; DANDA
 (0x0965	?E)			; DOUBLE DANDA
 (0x0C00 0x0C7F	?E)			; ELSE
 (0x0C01 0x0C03	?a)			; post signs
 (0x0C05 0x0C14	?V)			; LETTER A .. LETTER AU
 (0x0C15 0x0C39 ?C)			; LETTER KA .. LETTER HA
 (0x0C29	?R)			; LETTER NNNA
 (0x0C31	?R)			; LETTER RRA
 (0x0C34	?R)			; LETTER LLLA
 (0x0C3E 0x0C40	?u)			; VOWEL SIGN AA, I, II (above)
 (0x0C41 0x0C44	?p)			; VOWEL SIGN U, UU, R, RR (post)
 (0x0C46 0x0C47	?u)			; VOWEL SIGN E, EE (above)
 (0x0C48	?t)			; VOWEL SIGN AI (two-part)
 (0x0C4A 0x0C4C	?u)			; VOWEL SIGN O, OO, AU (above)
 (0x0C4D	?H)			; SIGN VIRAMA (HALANT)
 (0x0C55	?u)			; LENGTH MARK (above)
 (0x0C56	?b)			; AI LENGTH MARK (below)
 (0x0C60 0x0C61	?V)			; LETTER VOCALIC RR, LL
 (0x0C7E	?Y)			; internal use
 (0x0C7F	?X)			; internal use
 )

;; Step 1 : Syllable identification and Halant movement.
(generator
 (0
  (cond
   ;; A syllable containing a two-part vowel sign.
   ("([CR](HC)*)(t)(a)?"
    < | (1 move-base-Halant) (3 0x0C46 0x0C56) (4 =) | >)

   ;; A syllable ending with vowel signs and/or a vowel modifier.
   ("([CR](HC)*)([ubp]+a?|a)"
    < | (1 move-base-Halant) (3 = *) | >)

   ;; Forced Halant form
   ("((RH)?(CH)*)(CH)N"
    (1 < | move-base-Halant | >)
    (4 < | move-base-Halant | >))

   ;; Forced Below form
   ("((RH)?(CH)*)(CH)J"
    (1 < | move-base-Halant >)
    (4 < | otf:telu=blwf | >))

   ;; A syllable without a vowel sign nor a vowel modifier.
   ("[CR](HC)*H?"
    < | move-base-Halant | >)

   ;; A syllable starting with an independent vowel.
   ("Va?"
    < | = * | > )

   ("." =))
  *)

 ;; Move Halant on the base consonant to the tail if the syllable ends
 ;; with a consonant.
 ;; A leading 0x0C7F means Halant movement.
 ;; A leading 0x0C7E means a syllable ending with a Halant.
 (move-base-Halant
  (cond
   (".*H$"
    0x0C7E = *)
   ("(.)(H)(.*)"
    0x0C7F (1 =) (3 = *) (2 =))
   (".*"
    = *))))

;; Step 2 : Move Matra if applicable.
;; The base consonant in a Halant-ending syllable is changed into Halant form.
(generator
 (0
  (cond
   ;;  1  2      3   4   5   6
   (" X(.)([CH]*)(u)?(b)?(p)?(a)? "
    | (1 =) (3 =) (4 =) (5 =) (2 = *) (6 =) |)
   (" Y(..)([^ ]*) "
    | (1 otf:telu=haln) (2 = *) |)
   ("." =))
  *))

;; Step 3 : Drive OTF tables.
(generator
 (0
  (cond
   (" ([^ ]*) "
    (1 otf:telu))
   ("."
    [ otf:telu=+ ]))
  *))

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