forked from mirror/vulkan-zig
110 lines
3.3 KiB
Zig
110 lines
3.3 KiB
Zig
const std = @import("std");
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const unicode = std.unicode;
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const testing = std.testing;
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fn Utf8Iterator(comptime ReadError: type) type {
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return struct {
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const Self = @This();
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pub const Stream = std.io.InStream(ReadError);
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in: *Stream,
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pub fn init(in: *Stream) Self {
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return Self{
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.in = in
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};
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}
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pub fn next(self: *Self) !?u32 {
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var cp: [4]u8 = undefined;
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if ((try self.in.readFull(cp[0 .. 1])) != 1) {
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return null;
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}
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const cp_len = try unicode.utf8ByteSequenceLength(cp[0]);
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try self.in.readNoEof(cp[1 .. cp_len]);
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return try unicode.utf8Decode(cp[0 .. cp_len]);
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}
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};
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}
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pub fn PeekUtf8Iterator(comptime buffer_size: usize, comptime ReadError: type) type {
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return struct {
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const Self = @This();
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pub const Stream = Utf8Iterator(ReadError).Stream;
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it: Utf8Iterator(ReadError),
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buf: [buffer_size]u32,
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head: usize,
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size: usize,
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pub fn init(in: *Utf8Iterator(ReadError).Stream) Self {
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return Self{
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.it = Utf8Iterator(ReadError).init(in),
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.buf = undefined,
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.head = 0,
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.size = 0
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};
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}
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pub fn next(self: *Self) !?u32 {
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if (self.size > 0) {
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const cp = self.buf[self.head];
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self.head = (self.head + 1) % buffer_size;
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self.size -= 1;
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return cp;
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}
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return try self.it.next();
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}
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pub fn peek(self: *Self, offset: usize) !?u32 {
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std.debug.assert(offset < buffer_size);
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while (self.size <= offset) {
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const cp = (try self.it.next()) orelse return null;
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self.buf[(self.head + self.size) % buffer_size] = cp;
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self.size += 1;
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}
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return self.buf[(self.head + offset) % buffer_size];
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}
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pub fn peekNoEof(self: *Self, offset: usize) !?u32 {
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return (try self.peek(offset)) orelse return error.EndOfStream;
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}
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pub fn discard(self: *Self, amount: usize) void {
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std.debug.assert(amount < self.size);
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var i: usize = 0;
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while (i < amount) : (i += 1) {
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_ = self.next();
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}
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}
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};
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}
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test "PeekUtf8Iterator" {
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var slice_in = std.io.SliceInStream.init("abcd");
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var it = PeekUtf8Iterator(4, std.io.SliceInStream.Error).init(&slice_in.stream);
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testing.expect((try it.peek(0)).? == 'a');
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testing.expect((try it.peek(1)).? == 'b');
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testing.expect((try it.peek(2)).? == 'c');
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testing.expect((try it.peek(3)).? == 'd');
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testing.expect((try it.next()).? == 'a');
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testing.expect((try it.peek(0)).? == 'b');
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testing.expect((try it.peek(1)).? == 'c');
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testing.expect((try it.peek(2)).? == 'd');
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testing.expect((try it.next()).? == 'b');
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testing.expect((try it.peek(0)).? == 'c');
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testing.expect((try it.peek(1)).? == 'd');
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testing.expect((try it.peek(2)) == null);
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testing.expect((try it.next()).? == 'c');
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testing.expect((try it.peek(0)).? == 'd');
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testing.expect((try it.peek(1)) == null);
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testing.expectError(error.EndOfStream, it.peekNoEof(1));
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}
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