;; MLYM-OTF.flt -- Font Layout Table for Malayalam OpenType font
;; Copyright (C) 2003, 2004, 2005
;;   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> MLYM-OTF.flt
;;;
;;; For Malayalam OpenType fonts to draw the reformed Malayalam script.

;; The first stage is to extract a syllable and re-order characters.
(category
 ;; C: consonant (except for BPR)
 ;; B: consonant that is the subject of "blws" feature
 ;; P: consonant that is the subject of "pstf" feature
 ;; R: consonant RA
 ;; H: HALANT (VIRAMA)
 ;; m: MATRA (Mpre)
 ;; p: MATRA (Mpost)
 ;; t: MATRA (two-part: Mpre+Mpost)
 ;; A: vowel modifier (post) (ANUSVARA and VISARGA)
 ;; V: independent vowel
 ;; N: ZWNJ (ZERO WIDTH NON-JOINER)
 ;; J: ZWJ (ZERO WIDTH JOINER)
 ;; E: else (all other independnt characters)
 (0x0D00 0x0D7F	?E)			; else
 (0x0D02 0x0D03	?A)			; ANUSVARA & VISARGA
 (0x0D05 0x0D14	?V)			; independent vowel
 (0x0D15 0x0D39 ?C)			; consonant

 ;; Accorind to www.microsoft.com/typography/otfntdev/indicot/appen.htm,
 ;; these must be classified into 'B' category, but at least, it
 ;; doesn't work with this font
 ;; http://www.supersoftweb.com/THOOLIUC.TTF
 ;;(0x0D1F	?B)			; TTA
 ;;(0x0D23	?B)			; NNA
 ;;(0x0D26	?B)			; DA
 (0x0D2F	?P)			; YA
 (0x0D30	?R)			; RA
 (0x0D32	?B)			; LA
 (0x0D35	?P)			; VA
 (0x0D3E 0x0D43	?p)			; dependent vowel (Mpost)
 (0x0D46 0x0D48	?m)			; dependent vowel (Mpre)
 (0x0D4A 0x0D4C ?t)			; dependent vowel (two-part)
 (0x0D4D	?H)			; VIRAMA (HALANT)
 (0x0D57	?p)			; dependent vowel (Mpost)
 (0x0D60	?V)			; VOCALIC RR
 (0x0D61	?V)			; VOCALIC LL
 (0x200C	?N)			; ZWNJ
 (0x200D	?J)			; ZWJ
 (0x0D7D	?x)			; marker inserted before base-C
 (0x0D7E	?y)			; marker inserted after base-C
 (0x0D7F	?z)			; marker inserted before last Ra
 )

;; The 1st stage is to extract a syllable while moving a Halant
;; following Cbase to the tail and partitioning two-part matras into
;; parts.
(generator
 (0
  (cond
   ;; If [CR]H is followed by ZWNJ/ZWJ, move ZWNJ/ZWJ) to the head so
   ;; that the later stages find it quickly.
   ("([CBPR]H)([NJ])"
    < | (2 =) (1 = =) | >)

   ;; A syllable starting with a consonant and ending with a vowel
   ;; and/or a vowel modifier.
   ("(([CBPR]H)*[CBPR])([pmt]A?|A)"
    < | (1 move-halant) (3 partition = =) | >)

   ;; A syllable starting with a consonant and ending without a vowel
   ;; nor a vowel modifier.
   ("(([CBPR]H)*[CBPR])(H)?"
    < | (1 move-halant) (3 =) | >)

   ;; A syllable starting with an independent vowel.
   ("(VA?)"
    < | (1 = *) | >)

   ;; Other independent character.
   ("." =))
  *)

 ;; Move Halant to the tail if necessary.  Insert 0x0D7D before Cbase,
 ;; 0x0D7E after Cbase, 0x0D7F before the tailing RH (if any).  They
 ;; work as markers in the following stages.
 (move-halant
  (cond
   ;; In the first two cases, we don't have to move Halant.
   ("[BPR]$"				; Single consonant.
    0x0D7D 0x0D7E =)
   ("(([CBPR]H)*)(C)$"			; Cbase is at tail.
    (1 = *) 0x0D7D (3 =) 0x0D7E)
   ;; In the following cases, we must move Halant to the tail.
   ("(([CBPR]H)*)([C])H(([BR]H)*)(R)$"	; Cbase is at head or middle.
    (1 = *) 0x0D7D (3 =) 0x0D7E (4 = *) 0x0D7F 0x0D30 0x0D4D)
   ("(([CBPR]H)*)([C])H(([BR]H)*[BP])$" ; Cbase is at head or middle.
    (1 = *) 0x0D7D (3 =) 0x0D7E (4 = *) 0x0D4D)
   ("(RH)?(.)H(.*)$"			; No Cbase, move the first
					; Halant to the tail.
    (1 = *) 0x0D7D (2 = ) 0x0D7E (3 = *) 0x0D4D)))

 ;; Partition two-part matras into parts.
 (partition
  (cond
   ((0x0D4A)	0x0D46 0x0D3E)
   ((0x0D4B)	0x0D47 0x0D3E)
   ;; Unicode suggests this partitioning:
   ((0x0D4C)	0x0D46 0x0D57)
   ;; but it is questionable.  Perhaps, this substitution is better.
   ;; ((0x0D4C)	0x0D57)
   )))

;; The 2nd stage is to apply GSUB for prebase part.
(generator
 (0
  (cond
   ;; Originally [CBPR]H is followed by ZWNJ.  Apply no feature (just
   ;; cmap).
   (" N([^ ]*) "
    (1 otf:mlym=+))

   ;; Originally [CBPR]H is followed by ZWJ.  Apply only GSUB haln
   ;; feature.
   (" J([^ ]*) "
    (1 otf:mlym=haln+))

   ;; Syllable starting with a consonant should match this pattern.
   (" ([^ y]*)y([^ z]*)(z..)?([^ ]*) "
    |
    (1 otf:mlym=~blwf,~pstf,~blws,~psts,*+) ; Prebase part.
    0x0D7E				   ; Preserve this marker.
    (2 = *)				   ; Postbase part.
    (3 = *)				   ; Optional tailing RH.
    (4 = *)				   ; Optional Mpost.
    |)

   ;; A syllable starting with an independent vowel.
   (" ([^ ]*) "
    (1 otf:mlym+))

   ;; Any other independent character.  Apply no feature (just cmap).
   ("."
    [ otf:mlym=+ ] ))
  *))

;; The 3rd stage is to move Mpre (if any) and tailing RH (if any)
;; forward to just before the base consonant.
(generator
 (0
  (cond
   (" ([^x]*)(.)xy([^ zm]*)(z(..))?(m)?([^ ]*) "
    | (1 = *) (4 (5 otf:mlym=pstf+)) (6 =) 0x0D7D (2 =) (3 = *) (7 = *) |)
   (" ([^x]*)x(.)y([^ zm]*)(z(..))?(m)?([^ ]*) "
    | (1 = *) (4 (5 otf:mlym=pstf+)) (6 =) 0x0D7D (2 =) (3 = *) (7 = *) |)
   (" xy([^ m]*)(m)?([^ ]*) "
    | (2 =) 0x0D7D (1 = *) (3 = *) |)
   ("[NJ]")
   ("."
    = ))
  *))

;; The 4th stage is to apply GSUB to postbase part.
(generator
 (0
  (cond
   (" ([^x]*)x(.H) "
    | (1 = *) (2 otf:mlym=haln) |)
   (" ([^x]*)x([^ ]*) "
    | (1 = *) (2 otf:mlym=~akhn,~haln,blwf,pstf,vatu,*+) |)
   ("." =))
  *))



;; The 5th (last) stage is to apply GPOS features.
(generator
 (0
  (cond
   (" ([^ ]*) " (1 otf:mlym=))
   ("." =))
  *))

;; Local Variables:
;; mode: emacs-lisp
;; End: