Fg-optional-arabic.bin Here

// ... load rule table from body_offset fclose(f); return hdr;

body.append(len(inputs)) for ch in inputs: body.extend(struct.pack('<I', ch)) # Unicode codepoint

def parse_header(self): self.magic = self.data[:4] self.version = int.from_bytes(self.data[4:8], 'little') self.rule_count = int.from_bytes(self.data[8:12], 'little') # ... parse rules When shaping Arabic text, after mandatory shaping, apply optional rules: fg-optional-arabic.bin

print(f"Generated output_bin_path with rule_count rules") If this file is intended for a specific engine, use its tooling:

FGHeader* load_fg_optional(const char* path) FILE* f = fopen(path, "rb"); if (!f) return NULL; FGHeader* hdr = malloc(sizeof(FGHeader)); fread(hdr, sizeof(FGHeader), 1, f); if (hdr->magic != 0x414F4746) // 'FGOA' in little-endian free(hdr); fclose(f); return NULL; 'little') self.rule_count = int.from_bytes(self.data[8:12]

# Write each rule as: input_len (1B), inputs (4B each), output_len (1B), outputs (4B each), priority (1B) for rule in rules: inputs = rule['input'] outputs = rule['output'] if isinstance(rule['output'], list) else [rule['output']]

# Hypothetical compiler hb-compile-features -f optional-arabic.txt -o fg-optional-arabic.bin 4.1 Loading in a C/C++ Application #include <stdio.h> #include <stdint.h> typedef struct uint32_t magic; uint32_t version; uint32_t rule_count; uint32_t body_offset; FGHeader; after mandatory shaping

# Buffer for body body = bytearray()

body.append(rule.get('priority', 50))

import struct with open("fg-optional-arabic.bin", "rb") as f: magic = f.read(4) version = struct.unpack("<I", f.read(4))[0] rule_count = struct.unpack("<I", f.read(4))[0] print(f"Magic: magic, Version: version, Rules: rule_count") If you need to create such a file (e.g., for a custom Arabic shaper), follow this pipeline: 3.1 Source Rule Definition (e.g., rules.json ) "version": 2, "language": "ara", "optional_features": [ "name": "lam_alef_ligature", "input": [0x0644, 0x0627], "output": 0xFEF5, "condition": "diacritic_free", "priority": 90 , "name": "kashida_after_alef", "input": [0x0627], "output": [0x0627, 0x0640], "condition": "justify_mode", "priority": 30 ]