PdfPig/src/UglyToad.PdfPig.Tokenization/NameTokenizer.cs at dd505465596f375ac537a7c72a10e4c2b9715bef · rhuijben/PdfPig · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
namespace UglyToad.PdfPig.Tokenization
{
    using System;
    using System.Text;
    using Core;
    using Tokens;

#if NET
    using System.Text.Unicode;
#endif

    internal sealed class NameTokenizer : ITokenizer
    {
#if NET
        static NameTokenizer()
        {
            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
        }
#endif

        public bool ReadsNextByte => false;

        public bool TryTokenize(byte currentByte, IInputBytes inputBytes, out IToken token)
        {
            token = null;

            if (currentByte != '/')
            {
                return false;
            }

            using var bytes = new ArrayPoolBufferWriter<byte>();

            bool escapeActive = false;
            int postEscapeRead = 0;
            Span<char> escapedChars = stackalloc char[2];

            while (inputBytes.Peek() is { } b)
            {
                if (b == '#')
                {
                    escapeActive = true;
                }
                else if (escapeActive)
                {
                    if (ReadHelper.IsHex((char)b))
                    {
                        escapedChars[postEscapeRead] = (char)b;
                        postEscapeRead++;

                        if (postEscapeRead == 2)
                        {
                            // We validated that the char is hex. So assume ASCII rules apply and shortcut hex decoding
                            int high = escapedChars[0] <= '9' ? escapedChars[0] - '0' : ((escapedChars[0] & 0xF) + 9);
                            int low = escapedChars[1] <= '9' ? escapedChars[1] - '0' : ((escapedChars[1] & 0xF) + 9);

                            byte characterToWrite = (byte)(high * 16 + low);

                            bytes.Write(characterToWrite);

                            escapeActive = false;
                            postEscapeRead = 0;
                        }
                    }
                    else
                    {
                        bytes.Write((byte)'#');

                        if (postEscapeRead == 1)
                        {
                            bytes.Write((byte)escapedChars[0]);
                        }

                        if (ReadHelper.IsEndOfName(b))
                        {
                            break;
                        }

                        if (b == '#')
                        {
                            // Make it clear what's going on, we read something like #m#AE
                            // ReSharper disable once RedundantAssignment
                            escapeActive = true;
                            postEscapeRead = 0;
                            continue;
                        }

                        bytes.Write(b);
                        escapeActive = false;
                        postEscapeRead = 0;
                    }

                }
                else if (ReadHelper.IsEndOfName(b))
                {
                    break;
                }
                else
                {
                    bytes.Write(b);
                }

                inputBytes.MoveNext();
            }

#if NET8_0_OR_GREATER
            var byteArray = bytes.WrittenSpan;
            bool isValidUtf8 = Utf8.IsValid(byteArray);
#else
            var byteArray = bytes.WrittenSpan.ToArray();
            bool isValidUtf8 = ReadHelper.IsValidUtf8(byteArray);
#endif

            var str = isValidUtf8
                ? Encoding.UTF8.GetString(byteArray)
                : Encoding.GetEncoding("windows-1252").GetString(byteArray);

            token = NameToken.Create(str);

            return true;
        }
    }
}