[hackers] [libgrapheme] Add generating code for bidirectional character mirror mappings || Laslo Hunhold

[git]

commit 77e30a69ce0807fbee01d43eebedda34b54f41af
Author:     Laslo Hunhold <d...@frign.de>
AuthorDate: Wed May 24 18:05:39 2023 +0200
Commit:     Laslo Hunhold <d...@frign.de>
CommitDate: Wed May 24 18:05:39 2023 +0200

    Add generating code for bidirectional character mirror mappings
    
    Signed-off-by: Laslo Hunhold <d...@frign.de>

diff --git a/gen/bidirectional.c b/gen/bidirectional.c
index 469b9cf..3dd034e 100644
--- a/gen/bidirectional.c
+++ b/gen/bidirectional.c
@@ -402,9 +402,43 @@ fill_missing(uint_least32_t cp)
        }
 }
 
+static struct properties *prop_mirror = NULL;
+
+static int
+mirror_callback(const char *file, char **field, size_t nfields, char *comment,
+                void *payload)
+{
+       uint_least32_t cp, cp_mirror;
+
+       (void)file;
+       (void)comment;
+       (void)payload;
+
+       hextocp(field[0], strlen(field[0]), &cp);
+
+       cp_mirror = cp;
+
+       if (nfields >= 2 && strlen(field[1]) > 0 &&
+           hextocp(field[1], strlen(field[1]), &cp_mirror)) {
+               return 1;
+       }
+
+       prop_mirror[cp].property = (int_least32_t)cp_mirror - (int_least32_t)cp;
+
+       return 0;
+}
+
+static int_least64_t
+get_value(const struct properties *prop, size_t offset)
+{
+       return prop[offset].property;
+}
+
 int
 main(int argc, char *argv[])
 {
+       struct properties_compressed comp_mirror;
+       struct properties_major_minor mm_mirror;
        size_t i;
 
        (void)argc;
@@ -438,5 +472,32 @@ main(int argc, char *argv[])
        }
        printf("};\n");
 
+       /*
+        * allocate property buffer for all 0x110000 codepoints
+        *
+        * the buffers contain the offset from the "base" character
+        * to the respective mirrored character. By callocing we set all
+        * fields to zero, which is also the Unicode "default" in the sense
+        * that the coe point is its mirror (unless we fill it in)
+        */
+       if (!(prop_mirror = calloc(UINT32_C(0x110000), sizeof(*prop_mirror)))) {
+               fprintf(stderr, "calloc: %s\n", strerror(errno));
+               exit(1);
+       }
+       parse_file_with_callback(FILE_BIDI_MIRRORING, mirror_callback, NULL);
+
+       /* compress properties */
+       properties_compress(prop_mirror, &comp_mirror);
+
+       fprintf(stderr, "%s: mirror-LUT compression-ratio: %.2f%%\n", argv[0],
+               properties_get_major_minor(&comp_mirror, &mm_mirror));
+
+       /* print tables */
+       properties_print_lookup_table("mirror_major", mm_mirror.major, 0x1100);
+       printf("\n");
+       properties_print_derived_lookup_table("mirror_minor", mm_mirror.minor,
+                                             mm_mirror.minorlen, get_value,
+                                             comp_mirror.data);
+
        return 0;
 }