1 files changed, 82 insertions, 0 deletions

diff --git a/src/WidthData.zig b/src/WidthData.zig
new file mode 100644
index 0000000..32f8658
--- /dev/null
+++ b/src/WidthData.zig
@@ -0,0 +1,82 @@
+const std = @import("std");
+const builtin = @import("builtin");
+const compress = std.compress;
+const mem = std.mem;
+const testing = std.testing;
+
+const GraphemeData = @import("GraphemeData");
+
+allocator: mem.Allocator,
+g_data: GraphemeData,
+s1: []u16 = undefined,
+s2: []i3 = undefined,
+
+const Self = @This();
+
+pub fn init(allocator: mem.Allocator) !Self {
+    const decompressor = compress.deflate.decompressor;
+    const in_bytes = @embedFile("dwp");
+    var in_fbs = std.io.fixedBufferStream(in_bytes);
+    var in_decomp = try decompressor(allocator, in_fbs.reader(), null);
+    defer in_decomp.deinit();
+    var reader = in_decomp.reader();
+
+    const endian = builtin.cpu.arch.endian();
+
+    var self = Self{
+        .allocator = allocator,
+        .g_data = try GraphemeData.init(allocator),
+    };
+
+    const stage_1_len: u16 = try reader.readInt(u16, endian);
+    self.s1 = try allocator.alloc(u16, stage_1_len);
+    for (0..stage_1_len) |i| self.s1[i] = try reader.readInt(u16, endian);
+
+    const stage_2_len: u16 = try reader.readInt(u16, endian);
+    self.s2 = try allocator.alloc(i3, stage_2_len);
+    for (0..stage_2_len) |i| self.s2[i] = @intCast(try reader.readInt(i8, endian));
+
+    return self;
+}
+
+pub fn deinit(self: *Self) void {
+    self.allocator.free(self.s1);
+    self.allocator.free(self.s2);
+    self.g_data.deinit();
+}
+
+/// codePointWidth returns the number of cells `cp` requires when rendered
+/// in a fixed-pitch font (i.e. a terminal screen). This can range from -1 to
+/// 3, where BACKSPACE and DELETE return -1 and 3-em-dash returns 3. C0/C1
+/// control codes return 0. If `cjk` is true, ambiguous code points return 2,
+/// otherwise they return 1.
+pub inline fn codePointWidth(self: Self, cp: u21) i3 {
+    return self.s2[self.s1[cp >> 8] + (cp & 0xff)];
+}
+
+test "codePointWidth" {
+    try testing.expectEqual(@as(i3, 0), codePointWidth(0x0000)); // null
+    try testing.expectEqual(@as(i3, -1), codePointWidth(0x8)); // \b
+    try testing.expectEqual(@as(i3, -1), codePointWidth(0x7f)); // DEL
+    try testing.expectEqual(@as(i3, 0), codePointWidth(0x0005)); // Cf
+    try testing.expectEqual(@as(i3, 0), codePointWidth(0x0007)); // \a BEL
+    try testing.expectEqual(@as(i3, 0), codePointWidth(0x000A)); // \n LF
+    try testing.expectEqual(@as(i3, 0), codePointWidth(0x000B)); // \v VT
+    try testing.expectEqual(@as(i3, 0), codePointWidth(0x000C)); // \f FF
+    try testing.expectEqual(@as(i3, 0), codePointWidth(0x000D)); // \r CR
+    try testing.expectEqual(@as(i3, 0), codePointWidth(0x000E)); // SQ
+    try testing.expectEqual(@as(i3, 0), codePointWidth(0x000F)); // SI
+
+    try testing.expectEqual(@as(i3, 0), codePointWidth(0x070F)); // Cf
+    try testing.expectEqual(@as(i3, 1), codePointWidth(0x0603)); // Cf Arabic
+
+    try testing.expectEqual(@as(i3, 1), codePointWidth(0x00AD)); // soft-hyphen
+    try testing.expectEqual(@as(i3, 2), codePointWidth(0x2E3A)); // two-em dash
+    try testing.expectEqual(@as(i3, 3), codePointWidth(0x2E3B)); // three-em dash
+
+    try testing.expectEqual(@as(i3, 1), codePointWidth(0x00BD)); // ambiguous halfwidth
+
+    try testing.expectEqual(@as(i3, 1), codePointWidth('é'));
+    try testing.expectEqual(@as(i3, 2), codePointWidth('😊'));
+    try testing.expectEqual(@as(i3, 2), codePointWidth('统'));
+}