;; MLYM-OTF.flt -- Font Layout Table for Malayalam OpenType font
;; Copyright (C) 2003, 2004, 2005, 2007, 2008  AIST (H15PRO112)
;; See the end for copying conditions.

(font layouter mlym-otf nil
      (font (nil nil unicode-bmp :otf=mlym=akhn)))

;;; <li> MLYM-OTF.flt
;;;
;;; For Malayalam OpenType fonts to draw the reformed Malayalam script.

(category
 ;; C: consonant (except for R, B, and P)
 ;; R: consonant RA
 ;; B: consonant (below)
 ;; P: consonant (post)
 ;; H: HALANT
 ;; m: vowel sign (pre)
 ;; b: vowel sign (below)
 ;; p: vowel sign (post)
 ;; A: vowel modifier (post)
 ;; V: independent vowel
 ;; N: ZWNJ (ZERO WIDTH NON-JOINER)
 ;; J: ZWJ (ZERO WIDTH JOINER)
 ;; X: generic
 ;; Z: internal use
 (0x0D00 0x0D7F	?X)			; generic
 (0x0D00	?Z)			; internal use
 (0x0D02 0x0D03	?A)			; SIGN ANUSVARA .. VISARGA
 (0x0D05 0x0D14	?V)			; LETTER A .. AU
 (0x0D15 0x0D39 ?C)			; LETTER KA .. HA
 (0x0D2F	?P)			; LETTER YA
 (0x0D30	?R)			; LETTER RA
 (0x0D32	?B)			; LETTER LA
 (0x0D35	?P)			; LETTER VA
 (0x0D3E 0x0D44	?p)			; VOWEL SIGN AA .. VOCALIC RR
 (0x0D46 0x0D48	?m)			; VOWEL SIGN E .. AI
 (0x0D4D	?H)			; SIGN VIRAMA
 (0x0D57	?p)			; AU LENGTH MARK
 (0x0D60 0x0D61	?V)			; LETTER VOCALIC RR .. VOCALIC LL
 (0x0D62 0x0D63 ?b)			; VOWEL SIGN VOCALIC L .. LL
 (0x0D7A 0x0D7F ?C)			; LETTER CHILLU NN .. K
 (0x0964 0x0965	?X)			; DANDA .. DOUBLE DANDA
 (0x200C	?N)			; ZWNJ
 (0x200D	?J)			; ZWJ
 )

;; Decompose two-part vowels.
(generator
 (0
  (cond
   ((0x0D4A)
    0x0D46 0x0D3E)
   ((0x0D4B)
    0x0D47 0x0D3E)
   ((0x0D4C)
    0x0D46 0x0D57)
   ("." =))
  *))

;; Syllable identification and reordering.  
;; Put the mark 0x0D00 before the first pre-base consonant and after
;; the base consonant.
(generator
 (0
  (cond
   ;; A syllable with a left vowel sign.
   ;;1      2          3  4
   ("([CRBP](H[CRBP])*)(m)(p?A?)"
    < | (3 =) (1 get-rh) 0x0D00 (1 move-h) (4 = *) | >)

   ;; A syllable with a right vowel sign, a below vowel sign
   ;; and/or a vowel modifier.
   ;;1      2          3
   ("([CRBP](H[CRBP])*)(bA?|pA?|A)"
    < | (1 get-rh) 0x0D00 (1 move-h) (3 = *) | >)

   ;; Explicit Halant / forced chillu form is cut off from the preceders.
   ("(([CRBP]H)*)([CRBP]H[NJ])"
    (1 cut-off) (3 < | = * | >))

   ;; A syllable with no vowel signs/modifiers.
   ("([CRBP](H[CRBP])*H?)"
    < | (1 get-rh) 0x0D00 (1 move-h) | >)

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

   ("." =))
  *)

 ;; Extract RH that will be moved to the left.
 (get-rh
  (cond
   (".+HR$"
    0x0D30 0x0D4D)))

 ;; Move the halant after the base consonant to the end.
 ;; Fill the resulting gap with 0x0D00.
 ;; Remove final RH if any.
 (move-h
  (cond
   ;; There is a C and the syllable ends with an R.  Remove final RH.
   ("([CRBPH]*C)H([RBPH]*)R$"
    (1 = *) 0x0D00 (2 = *))

   ;; The syllable ends other than R.  Move H.
   ("([CRBPH]*C)(H)([RBPH]+)$"
    (1 = *) 0x0D00 (3 = *) (2 =))

   ;; No C and end with R.  The first consonant will be the base.  Remove RH.
   ("([RBP])H([RBPH]*)R$"
    (1 =) 0x0D00 (2 = *))

   ;; No C and not end with R.  Move H.
   ("([RBP])(H)([RBPH]+)$"
    (1 =) 0x0D00 (3 = *) (2 =))

   ;; Otherwise, no need to move H.
   (".+"
    = * 0x0D00)))

 ;; If there are some letters make them a separate syllable.
 (cut-off
  (cond
   (".+"
    < | = * | >)))
 )

;; Apply GSUB features.
;; According to Microsoft Typography
;; <http://www.microsoft.com/typography/otfntdev/malayot/features.htm>
;; 'chillu' are generated with the 'haln' feature.  However, some
;; fonts generate them with 'half'.
(generator
 (0
  (cond
   ;; Ordinary syllable.  We must avoid applying 'blwf' and 'pstf' to
   ;; the first consonant.  Also 'haln' and 'half' must be avoided
   ;; because chillu does not appear at the beginning of a word.  Thus
   ;; we apply only 'akhn' here and postpone applying other features
   ;; to the next stage.
   ;; 1  2      3         4  5
   (" (m?(RH)?Z)([CRBPH]+)(Z)([RBPHbpA]*) "
    | (1 = *) (3 otf:mlym=akhn+) (4 =) (5 otf:mlym=blwf,pstf+) |)

   ;; Explicit Halant.
   (" [CRBP]HN "
    = *)

   ;; Forced chillu form.
   (" ([CRBP]H)(J) "
    | (1 otf:mlym=haln,half+) (2 =) |)

   ;; Sequence that was cut off from a forced form.  Again we apply
   ;; only 'akhn' here.
   (" ([CRBPH]+) "
    | (1 otf:mlym=akhn+) |)

   ("." =))
  *))

;; Apply postoponed GSUB features to ordinary syllables.
(generator
 (0
  (cond
   ;; Ordinary syllable.
   ;; 1  2          3      4 
   (" (m?(RH)?Z[^Z])([^Z]*)(Z[^ ]*) "
    | (1 = *) (3 otf:mlym=blwf,half,pstf,haln+) (4 = *) |)

   ;; Explicit Halant / Forced chillu must not change to others.
   (" ([^ ]+)[NJ] "
    | (1 = *) |)

   ;; Cut off sequence.
   (" ([^ ])([^ ]*) "
    | (1 =) (2 otf:mlym=blwf,half,pstf,haln+) |)

   ("." =))
  *))

;; Second reordering.  If there are glyphs before the base, move left
;; vowel sign and RH to the left of the base.
(generator
 (0
  (cond
   ;; 1   2     3      4      5
   (" (m)?(RH)?Z([^Z]*)([^Z])Z([^ ]*) "
    | (3 = *) (1 =) (2 otf:mlym=pstf+) (4 =) (5 = *) |)

   ("." =))
  *))

;; Apply substitutions and GPOS features.
(generator
 (0
  (cond
   (" ([^ ]+) "
    (1 otf:mlym=pres,abvs,blws,psts+abvm,blwm,dist))
   ("."
    [ = ]))
  *))

;; Copyright (C) 2003, 2004, 2005, 2007, 2008
;;   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., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

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