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Merged
BobLd merged 1 commit into from
Oct 28, 2025
Merged

Avoid reading ahead and then seeking back #1189

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7 changes: 6 additions & 1 deletion src/UglyToad.PdfPig.Core/ReadHelper.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -24,12 +24,17 @@ public static class ReadHelper
/// </summary>
public const byte AsciiCarriageReturn = 13;

/// <summary>
/// The tab '\t' character.
/// </summary>
public const byte AsciiTab = 9;

private static readonly HashSet<int> EndOfNameCharacters =
[
' ',
AsciiCarriageReturn,
AsciiLineFeed,
9,
AsciiTab,
'>',
'<',
'[',
Expand Down
11 changes: 11 additions & 0 deletions src/UglyToad.PdfPig.Core/StreamInputBytes.cs
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Expand Up @@ -96,6 +96,17 @@ public bool IsAtEnd()
/// <inheritdoc />
public void Seek(long position)
{
var current = CurrentOffset;
if (position == current)
{
return;
}
else if (peekByte.HasValue && position == current + 1)
{
MoveNext();
return;
}

isAtEnd = false;
peekByte = null;

Expand Down
2 changes: 1 addition & 1 deletion src/UglyToad.PdfPig.Fonts/Type1/Parser/Type1ArrayTokenizer.cs
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Expand Up @@ -14,7 +14,7 @@ public sealed class Type1ArrayTokenizer : ITokenizer
/// <inheritdoc />
public bool ReadsNextByte { get; } = false;

private static readonly string[] Space = [" "];
private static readonly char[] Space = [' '];

/// <inheritdoc />
public bool TryTokenize(byte currentByte, IInputBytes inputBytes, out IToken token)
Expand Down
5 changes: 5 additions & 0 deletions src/UglyToad.PdfPig.Fonts/Type1/Parser/Type1FontParser.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -88,6 +88,11 @@ public static Type1Font Parse(IInputBytes inputBytes, int length1, int length2)
{
int offset = 0;

while (inputBytes.Peek() is { } b && ReadHelper.IsWhitespace(b))
{
inputBytes.MoveNext();
}

while (inputBytes.MoveNext())
{
if (inputBytes.CurrentByte == (byte)ClearToMark[offset])
Expand Down
65 changes: 43 additions & 22 deletions src/UglyToad.PdfPig.Fonts/Type1/Parser/Type1Tokenizer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@
{
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.Text;
using Core;
Expand Down Expand Up @@ -41,35 +42,43 @@ private Type1Token ReadNextToken()
do
{
skip = false;
while (bytes.MoveNext())
while (bytes.Peek() is { } b)
{
var b = bytes.CurrentByte;
var c = (char)b;

switch (c)
{
case '%':
bytes.MoveNext();
comments.Add(ReadComment());
break;
case '(':
bytes.MoveNext();
return ReadString();
case ')':
throw new InvalidOperationException("Encountered an end of string ')' outside of string.");
case '[':
bytes.MoveNext();
return new Type1Token(c, Type1Token.TokenType.StartArray);
case ']':
bytes.MoveNext();
return new Type1Token(c, Type1Token.TokenType.EndArray);
case '{':
bytes.MoveNext();
return new Type1Token(c, Type1Token.TokenType.StartProc);
case '}':
bytes.MoveNext();
return new Type1Token(c, Type1Token.TokenType.EndProc);
case '/':
{
var name = ReadLiteral();
bytes.MoveNext();
TryReadLiteral(out var name);
Debug.Assert(name != null);
return new Type1Token(name, Type1Token.TokenType.Literal);
}
case '<':
{
bytes.MoveNext();
var following = bytes.Peek();
if (following == '<')
{
Expand All @@ -81,6 +90,7 @@ private Type1Token ReadNextToken()
}
case '>':
{
bytes.MoveNext();
var following = bytes.Peek();
if (following == '>')
{
Expand All @@ -94,23 +104,24 @@ private Type1Token ReadNextToken()
{
if (ReadHelper.IsWhitespace(b))
{
bytes.MoveNext();
skip = true;
break;
}

if (b == 0)
{
bytes.MoveNext();
skip = true;
break;
}

if (TryReadNumber(c, out var number))
if (TryReadNumber(out var number))
{
return number;
}

var name = ReadLiteral(c);
if (name == null)
if (!TryReadLiteral(out var name))
{
throw new InvalidOperationException($"The binary portion of the type 1 font was invalid at position {bytes.CurrentOffset}.");
}
Expand Down Expand Up @@ -197,12 +208,21 @@ char GetNext()
return null;
}

private bool TryReadNumber(char c, out Type1Token numberToken)
private bool TryReadNumber(out Type1Token numberToken)
{
char GetNext()
{
bytes.MoveNext();
return (char)bytes.CurrentByte;
return (char)(bytes.Peek() ?? 0);
}

char c = (char)(bytes.Peek() ?? 0);

if (!((c >= '0' && c <= '9') || c is '+' or '-'))
{
// Easy out. Not a valid number
numberToken = null;
return false;
}

numberToken = null;
Expand Down Expand Up @@ -251,8 +271,6 @@ char GetNext()
else
{
// integer
bytes.Seek(bytes.CurrentOffset - 1);

numberToken = new Type1Token(sb.ToString(), Type1Token.TokenType.Integer);
return true;
}
Expand Down Expand Up @@ -309,7 +327,6 @@ char GetNext()
}
}

bytes.Seek(bytes.CurrentOffset - 1);
if (radix != null)
{
var number = Convert.ToInt32(sb.ToString(), int.Parse(radix.ToString(), CultureInfo.InvariantCulture));
Expand All @@ -323,14 +340,9 @@ char GetNext()
return true;
}

private string ReadLiteral(char? previousCharacter = null)
private bool TryReadLiteral(out string? value)
{
literalBuffer.Clear();
if (previousCharacter.HasValue)
{
literalBuffer.Append(previousCharacter);
}

do
{
var b = bytes.Peek();
Expand All @@ -350,8 +362,16 @@ private string ReadLiteral(char? previousCharacter = null)
literalBuffer.Append(c);
} while (bytes.MoveNext());

var literal = literalBuffer.ToString();
return literal.Length == 0 ? null : literal;
if (literalBuffer.Length > 0)
{
value = literalBuffer.ToString();
return true;
}
else
{
value = null;
return false;
}
}

private string ReadComment()
Expand All @@ -375,9 +395,10 @@ private string ReadComment()
private Type1DataToken ReadCharString(int length)
{
// Skip preceding space.
bytes.MoveNext();
// TODO: may be wrong
// bytes.MoveNext();
if (bytes.Peek() is { } ws && ReadHelper.IsWhitespace(ws))
{
bytes.MoveNext();
}

byte[] data = new byte[length];
for (int i = 0; i < length; i++)
Expand Down
5 changes: 4 additions & 1 deletion src/UglyToad.PdfPig.Tests/Tokenization/NumericTokenizerTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -91,7 +91,10 @@ public void OnlyParsesNumberPart()
Assert.True(result);
Assert.Equal(135.6654, AssertNumericToken(token).Data);

Assert.Equal('/', (char)input.Bytes.CurrentByte);
if (tokenizer.ReadsNextByte)
Assert.Equal('/', (char)input.Bytes.CurrentByte);
else
Assert.Equal('4', (char)input.Bytes.CurrentByte);
}

[Fact]
Expand Down
2 changes: 1 addition & 1 deletion src/UglyToad.PdfPig.Tokenization/ArrayTokenizer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ internal sealed class ArrayTokenizer : ITokenizer
{
private readonly bool usePdfDocEncoding;

public bool ReadsNextByte { get; } = false;
public bool ReadsNextByte => false;

public ArrayTokenizer(bool usePdfDocEncoding)
{
Expand Down
7 changes: 4 additions & 3 deletions src/UglyToad.PdfPig.Tokenization/CommentTokenizer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@

internal sealed class CommentTokenizer : ITokenizer
{
public bool ReadsNextByte { get; } = true;
public bool ReadsNextByte => false;

public bool TryTokenize(byte currentByte, IInputBytes inputBytes, out IToken token)
{
Expand All @@ -17,10 +17,11 @@ public bool TryTokenize(byte currentByte, IInputBytes inputBytes, out IToken tok
return false;
}

using var builder = new ValueStringBuilder();
using var builder = new ValueStringBuilder(stackalloc char[32]);

while (inputBytes.MoveNext() && !ReadHelper.IsEndOfLine(inputBytes.CurrentByte))
while (inputBytes.Peek() is { } c && !ReadHelper.IsEndOfLine(c))
{
inputBytes.MoveNext();
builder.Append((char) inputBytes.CurrentByte);
}

Expand Down
2 changes: 1 addition & 1 deletion src/UglyToad.PdfPig.Tokenization/DictionaryTokenizer.cs
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Expand Up @@ -11,7 +11,7 @@ internal class DictionaryTokenizer : ITokenizer
private readonly IReadOnlyList<NameToken> requiredKeys;
private readonly bool useLenientParsing;

public bool ReadsNextByte { get; } = false;
public bool ReadsNextByte => false;

/// <summary>
/// Create a new <see cref="DictionaryTokenizer"/>.
Expand Down
2 changes: 1 addition & 1 deletion src/UglyToad.PdfPig.Tokenization/EndOfLineTokenizer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@
public sealed class EndOfLineTokenizer : ITokenizer
{
/// <inheritdoc />
public bool ReadsNextByte { get; } = false;
public bool ReadsNextByte => false;

/// <inheritdoc />
public bool TryTokenize(byte currentByte, IInputBytes inputBytes, out IToken token)
Expand Down
2 changes: 1 addition & 1 deletion src/UglyToad.PdfPig.Tokenization/HexTokenizer.cs
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Expand Up @@ -5,7 +5,7 @@

internal sealed class HexTokenizer : ITokenizer
{
public bool ReadsNextByte { get; } = false;
public bool ReadsNextByte => false;

public bool TryTokenize(byte currentByte, IInputBytes inputBytes, out IToken token)
{
Expand Down
17 changes: 9 additions & 8 deletions src/UglyToad.PdfPig.Tokenization/NameTokenizer.cs
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Expand Up @@ -11,14 +11,14 @@

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

public bool ReadsNextByte { get; } = true;
public bool ReadsNextByte => false;

public bool TryTokenize(byte currentByte, IInputBytes inputBytes, out IToken token)
{
Expand All @@ -35,10 +35,8 @@ public bool TryTokenize(byte currentByte, IInputBytes inputBytes, out IToken tok
int postEscapeRead = 0;
Span<char> escapedChars = stackalloc char[2];

while (inputBytes.MoveNext())
while (inputBytes.Peek() is { } b)
{
var b = inputBytes.CurrentByte;

if (b == '#')
{
escapeActive = true;
Expand All @@ -52,8 +50,9 @@ public bool TryTokenize(byte currentByte, IInputBytes inputBytes, out IToken tok

if (postEscapeRead == 2)
{
int high = escapedChars[0] <= '9' ? escapedChars[0] - '0' : char.ToUpper(escapedChars[0]) - 'A' + 10;
int low = escapedChars[1] <= '9' ? escapedChars[1] - '0' : char.ToUpper(escapedChars[1]) - 'A' + 10;
// 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);

Expand Down Expand Up @@ -100,6 +99,8 @@ public bool TryTokenize(byte currentByte, IInputBytes inputBytes, out IToken tok
{
bytes.Write(b);
}

inputBytes.MoveNext();
}

#if NET8_0_OR_GREATER
Expand Down
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