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const std = @import("std");
const builtin = @import("builtin");
const compress = std.compress;
const mem = std.mem;
allocator: mem.Allocator,
cutoff: u21 = undefined,
cwcf_exceptions_min: u21 = undefined,
cwcf_exceptions_max: u21 = undefined,
cwcf_exceptions: []u21 = undefined,
multiple_start: u21 = undefined,
stage1: []u8 = undefined,
stage2: []u8 = undefined,
stage3: []i24 = undefined,
const Self = @This();
pub fn init(allocator: mem.Allocator) !Self {
const decompressor = compress.flate.inflate.decompressor;
const in_bytes = @embedFile("fold");
var in_fbs = std.io.fixedBufferStream(in_bytes);
var in_decomp = decompressor(.raw, in_fbs.reader());
var reader = in_decomp.reader();
const endian = builtin.cpu.arch.endian();
var self = Self{ .allocator = allocator };
self.cutoff = @intCast(try reader.readInt(u24, endian));
self.multiple_start = @intCast(try reader.readInt(u24, endian));
var len = try reader.readInt(u16, endian);
self.stage1 = try allocator.alloc(u8, len);
errdefer allocator.free(self.stage1);
for (0..len) |i| self.stage1[i] = try reader.readInt(u8, endian);
len = try reader.readInt(u16, endian);
self.stage2 = try allocator.alloc(u8, len);
errdefer allocator.free(self.stage2);
for (0..len) |i| self.stage2[i] = try reader.readInt(u8, endian);
len = try reader.readInt(u16, endian);
self.stage3 = try allocator.alloc(i24, len);
errdefer allocator.free(self.stage3);
for (0..len) |i| self.stage3[i] = try reader.readInt(i24, endian);
self.cwcf_exceptions_min = @intCast(try reader.readInt(u24, endian));
self.cwcf_exceptions_max = @intCast(try reader.readInt(u24, endian));
len = try reader.readInt(u16, endian);
self.cwcf_exceptions = try allocator.alloc(u21, len);
errdefer allocator.free(self.cwcf_exceptions);
for (0..len) |i| self.cwcf_exceptions[i] = @intCast(try reader.readInt(u24, endian));
return self;
}
pub fn deinit(self: *const Self) void {
self.allocator.free(self.stage1);
self.allocator.free(self.stage2);
self.allocator.free(self.stage3);
self.allocator.free(self.cwcf_exceptions);
}
/// Returns the case fold for `cp`.
pub fn caseFold(self: Self, cp: u21, buf: []u21) []const u21 {
if (cp >= self.cutoff) return &.{};
const stage1_val = self.stage1[cp >> 8];
if (stage1_val == 0) return &.{};
const stage2_index = @as(usize, stage1_val) * 256 + (cp & 0xFF);
const stage3_index = self.stage2[stage2_index];
if (stage3_index & 0x80 != 0) {
const real_index = @as(usize, self.multiple_start) + (stage3_index ^ 0x80) * 3;
const mapping = mem.sliceTo(self.stage3[real_index..][0..3], 0);
for (mapping, 0..) |c, i| buf[i] = @intCast(c);
return buf[0..mapping.len];
}
const offset = self.stage3[stage3_index];
if (offset == 0) return &.{};
buf[0] = @intCast(@as(i32, cp) + offset);
return buf[0..1];
}
/// Returns true when caseFold(NFD(`cp`)) != NFD(`cp`).
pub fn changesWhenCaseFolded(self: Self, cp: u21) bool {
var buf: [3]u21 = undefined;
const has_mapping = self.caseFold(cp, &buf).len != 0;
return has_mapping and !self.isCwcfException(cp);
}
fn isCwcfException(self: Self, cp: u21) bool {
return cp >= self.cwcf_exceptions_min and
cp <= self.cwcf_exceptions_max and
std.mem.indexOfScalar(u21, self.cwcf_exceptions, cp) != null;
}
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