1 files changed, 12 insertions, 1 deletions

diff --git a/src/Canonical.zig b/src/Canonical.zig
index d54e828..81d3eec 100644
--- a/src/Canonical.zig
+++ b/src/Canonical.zig
@@ -4,6 +4,7 @@ const compress = std.compress;
 const mem = std.mem;
 
 allocator: mem.Allocator,
+nfc: std.AutoHashMap([2]u21, u21),
 nfd: [][2]u21 = undefined,
 
 const Self = @This();
@@ -19,6 +20,7 @@ pub fn init(allocator: mem.Allocator) !Self {
     const endian = builtin.cpu.arch.endian();
     var self = Self{
         .allocator = allocator,
+        .nfc = std.AutoHashMap([2]u21, u21).init(allocator),
         .nfd = try allocator.alloc([2]u21, 0x110000),
     };
 
@@ -29,13 +31,17 @@ pub fn init(allocator: mem.Allocator) !Self {
         if (len == 0) break;
         const cp = try reader.readInt(u24, endian);
         self.nfd[cp][0] = @intCast(try reader.readInt(u24, endian));
-        if (len == 3) self.nfd[cp][1] = @intCast(try reader.readInt(u24, endian));
+        if (len == 3) {
+            self.nfd[cp][1] = @intCast(try reader.readInt(u24, endian));
+            try self.nfc.put(self.nfd[cp], @intCast(cp));
+        }
     }
 
     return self;
 }
 
 pub fn deinit(self: *Self) void {
+    self.nfc.deinit();
     self.allocator.free(self.nfd);
 }
 
@@ -43,3 +49,8 @@ pub fn deinit(self: *Self) void {
 pub inline fn toNfd(self: Self, cp: u21) [2]u21 {
     return self.nfd[cp];
 }
+
+// Returns the primary composite for the codepoints in `cp`.
+pub inline fn toNfc(self: Self, cps: [2]u21) ?u21 {
+    return self.nfc.get(cps);
+}