[indic] Add syllable recognition state machine

Using an incredible tool called Ragel.

src/Makefile.am

@@ -56,6 +56,7 @@ HBSOURCES += \
 	hb-ot-shape-complex-arabic.cc \
 	hb-ot-shape-complex-arabic-table.hh \
 	hb-ot-shape-complex-indic.cc \
+	hb-ot-shape-complex-indic-machine.hh \
 	hb-ot-shape-complex-indic-table.hh \
 	hb-ot-shape-complex-private.hh \
 	hb-ot-shape-private.hh \
@@ -121,6 +122,10 @@ GENERATORS = \
 
 EXTRA_DIST += $(GENERATORS)
 
+BUILT_SOURCES = hb-ot-shape-complex-indic-machine.hh
+hb-ot-shape-complex-indic-machine.hh: hb-ot-shape-complex-indic-machine.rl
+	$(AM_V_GEN)ragel -e -F1 -o $@ $^
+
 noinst_PROGRAMS = main test
 bin_PROGRAMS =
 

src/hb-ot-shape-complex-indic-machine.rl

@@ -0,0 +1,105 @@
+/*
+ * Copyright © 2011  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Behdad Esfahbod
+ */
+
+#ifndef HB_OT_SHAPE_COMPLEX_INDIC_MACHINE_HH
+#define HB_OT_SHAPE_COMPLEX_INDIC_MACHINE_HH
+
+#include "hb-private.hh"
+
+HB_BEGIN_DECLS
+
+%%{
+  machine indic_syllable_machine;
+  alphtype unsigned char;
+  write data;
+}%%
+
+%%{
+
+X    = 0;
+C    = 1;
+Ra   = 2;
+V    = 3;
+N    = 4;
+H    = 5;
+ZWNJ = 6;
+ZWJ  = 7;
+M    = 8;
+SM   = 9;
+VD   = 10;
+A    = 11;
+NBSP = 12;
+
+c = C | Ra;
+z = ZWJ|ZWNJ;
+matra_group = M N? H?;
+syllable_tail = SM? (VD VD?)?;
+
+action matched_syllable {
+  //fprintf (stderr, "Syll %d\n", p);
+}
+
+consonant_syllable =	(c.N? (z.H|H.z?))* c.N? A? (H.z? | matra_group*)? syllable_tail %(matched_syllable);
+vowel_syllable =	(Ra H)? V N? (z.H.c | ZWJ.c)? matra_group* syllable_tail;
+standalone_cluster =	(Ra H)? NBSP N? (z? H c)? matra_group* syllable_tail;
+non_indic = X;
+
+syllable =
+	  consonant_syllable
+	| vowel_syllable
+	| standalone_cluster
+	| non_indic
+	;
+
+main := syllable**;
+
+}%%
+
+
+#include <stdio.h>
+#include <string.h>
+
+static void
+find_syllables (hb_ot_shape_context_t *c)
+{
+  unsigned int p, pe, eof;
+  int cs;
+  %%{
+    write init;
+    getkey c->buffer->info[p].indic_category();
+  }%%
+
+  p = 0;
+  pe = eof = c->buffer->len;
+
+  %%{
+    write exec;
+  }%%
+}
+
+HB_END_DECLS
+
+#endif /* HB_OT_SHAPE_COMPLEX_INDIC_MACHINE_HH */

src/hb-ot-shape-complex-indic.cc

@@ -30,16 +30,18 @@ HB_BEGIN_DECLS
 
 
 /* buffer var allocations */
-#define indic_categories() var2.u32 /* indic shaping action */
+#define indic_category() var2.u8[0] /* indic_category_t */
+#define indic_position() var2.u8[1] /* indic_matra_category_t */
 
 #define INDIC_TABLE_ELEMENT_TYPE uint8_t
 
 /* Cateories used in the OpenType spec:
  * https://www.microsoft.com/typography/otfntdev/devanot/shaping.aspx
  */
-enum {
+enum indic_category_t {
   OT_X = 0,
   OT_C,
+  OT_Ra,
   OT_V,
   OT_N,
   OT_H,
@@ -147,7 +149,6 @@ static const hb_tag_t indic_other_features[] =
 };
 
 
-
 void
 _hb_ot_shape_complex_collect_features_indic (hb_ot_shape_planner_t *planner, const hb_segment_properties_t *props HB_UNUSED)
 {
@@ -158,6 +159,11 @@ _hb_ot_shape_complex_collect_features_indic	(hb_ot_shape_planner_t *planner, con
     planner->map.add_bool_feature (indic_other_features[i], true);
 }
 
+
+
+#include "hb-ot-shape-complex-indic-machine.hh"
+
+
 void
 _hb_ot_shape_complex_setup_masks_indic	(hb_ot_shape_context_t *c)
 {
@@ -165,11 +171,14 @@ _hb_ot_shape_complex_setup_masks_indic	(hb_ot_shape_context_t *c)
 
   for (unsigned int i = 0; i < count; i++)
   {
-    unsigned int this_type = get_indic_categories (c->buffer->info[i].codepoint);
+    unsigned int type = get_indic_categories (c->buffer->info[i].codepoint);
 
-    c->buffer->info[i].indic_categories() = this_type;
+    c->buffer->info[i].indic_category() = type & 0x0F;
+    c->buffer->info[i].indic_position() = type >> 4;
   }
 
+  find_syllables (c);
+
   hb_mask_t mask_array[ARRAY_LENGTH (indic_basic_features)] = {0};
   unsigned int num_masks = ARRAY_LENGTH (indic_basic_features);
   for (unsigned int i = 0; i < num_masks; i++)