Cache lines in Lexer and show original input when running into an error

src/ZoneCodeGeneratorLib/Parsing/Header/Impl/HeaderLexer.cpp

@@ -129,9 +129,9 @@ HeaderParserValue HeaderLexer::GetNextToken()
                 if (isspace(c))
                     break;
 
+                const auto pos = GetPreviousCharacterPos();
                 if(isdigit(c))
                 {
-                    const auto pos = GetPreviousCharacterPos();
                     bool isFloatingPointValue;
                     double doubleValue;
                     int integerValue;
@@ -150,12 +150,12 @@ HeaderParserValue HeaderLexer::GetNextToken()
 
                     const auto foundKeyword = m_keywords.find(identifier);
                     if (foundKeyword != m_keywords.end())
-                        return HeaderParserValue::Keyword(GetPreviousCharacterPos(), foundKeyword->second);
+                        return HeaderParserValue::Keyword(pos, foundKeyword->second);
 
-                    return HeaderParserValue::Identifier(GetPreviousCharacterPos(), new std::string(std::move(identifier)));
+                    return HeaderParserValue::Identifier(pos, new std::string(std::move(identifier)));
                 }
 
-                return HeaderParserValue::Character(GetPreviousCharacterPos(), static_cast<char>(c));
+                return HeaderParserValue::Character(pos, static_cast<char>(c));
             }
         }
 

src/ZoneCodeGeneratorLib/Parsing/Header/Impl/HeaderParserValue.cpp

@@ -134,7 +134,8 @@ HeaderParserValue::~HeaderParserValue()
 }
 
 HeaderParserValue::HeaderParserValue(HeaderParserValue&& other) noexcept
-    : m_type(other.m_type),
+    : m_pos(other.m_pos),
+      m_type(other.m_type),
       m_value(other.m_value)
 {
     other.m_value = ValueType();
@@ -142,6 +143,7 @@ HeaderParserValue::HeaderParserValue(HeaderParserValue&& other) noexcept
 
 HeaderParserValue& HeaderParserValue::operator=(HeaderParserValue&& other) noexcept
 {
+    m_pos = other.m_pos;
     m_type = other.m_type;
     m_value = other.m_value;
     other.m_value = ValueType();

src/ZoneCodeGeneratorLib/Parsing/ILexer.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "IParserLineStream.h"
 #include "Parsing/IParserValue.h"
 
 template<typename TokenType>
@@ -21,4 +22,5 @@ public:
 
     _NODISCARD virtual bool IsEof() = 0;
     _NODISCARD virtual const TokenPos& GetPos() = 0;
+    _NODISCARD virtual ParserLine GetLineForPos(const TokenPos& pos) const = 0;
 };

src/ZoneCodeGeneratorLib/Parsing/IParserLineStream.h

@@ -32,6 +32,7 @@ public:
 
     virtual ParserLine NextLine() = 0;
     virtual bool IncludeFile(const std::string& filename) = 0;
+    virtual void PopCurrentFile() = 0;
     _NODISCARD virtual bool IsOpen() const = 0;
     _NODISCARD virtual bool Eof() const = 0;
 };

src/ZoneCodeGeneratorLib/Parsing/Impl/AbstractLexer.h

@@ -16,19 +16,16 @@ class AbstractLexer : public ILexer<TokenType>
 
 protected:
     std::deque<TokenType> m_token_cache;
+    std::deque<ParserLine> m_line_cache;
     IParserLineStream* const m_stream;
 
+    unsigned m_line_index;
     unsigned m_current_line_offset;
-    bool m_peeked_next_line;
-    bool m_start;
-    ParserLine m_current_line;
-    ParserLine m_next_line;
 
     explicit AbstractLexer(IParserLineStream* stream)
         : m_stream(stream),
-          m_current_line_offset(0u),
+          m_line_index(0u),
-          m_peeked_next_line(false),
+          m_current_line_offset(0u)
-          m_start(true)
     {
     }
 
@@ -36,60 +33,63 @@ protected:
 
     int NextChar()
     {
-        if (m_current_line.IsEof())
+        while (true)
         {
-            if (m_start)
+            while (m_line_index >= m_line_cache.size())
-                m_start = false;
+            {
-            else
+                if (!m_line_cache.empty() && m_line_cache.back().IsEof())
                     return EOF;
+
+                m_line_cache.push_back(m_stream->NextLine());
             }
 
-        while (m_current_line_offset >= m_current_line.m_line.size())
+            if (m_current_line_offset >= m_line_cache[m_line_index].m_line.size())
             {
+                m_line_index++;
                 m_current_line_offset = 0;
-            if (m_peeked_next_line)
-            {
-                m_current_line = m_next_line;
-                m_peeked_next_line = false;
             }
             else
-            {
+                break;
-                m_current_line = m_stream->NextLine();
         }
 
-            if (m_current_line.IsEof())
+        return m_line_cache[m_line_index].m_line[m_current_line_offset++];
-                return EOF;
-        }
-
-        return m_current_line.m_line[m_current_line_offset++];
     }
 
     int PeekChar()
     {
-        if (m_current_line.IsEof())
+        auto peekLineOffset = m_current_line_offset;
+        auto peekLine = m_line_index;
+
+        while (true)
+        {
+            while (peekLine >= m_line_cache.size())
+            {
+                if (m_line_cache.back().IsEof())
                     return EOF;
 
-        if (m_current_line_offset >= m_current_line.m_line.size())
+                m_line_cache.push_back(m_stream->NextLine());
-        {
-            m_peeked_next_line = true;
-
-            do
-            {
-                m_next_line = m_stream->NextLine();
-                if (m_next_line.IsEof())
-                    return EOF;
-            }
-            while (m_next_line.m_line.empty());
-
-            return m_next_line.m_line[0];
             }
 
-        return m_current_line.m_line[m_current_line_offset];
+            if (peekLineOffset >= m_line_cache[peekLine].m_line.size())
+            {
+                peekLine++;
+                peekLineOffset = 0;
+            }
+            else
+                break;
+        }
+
+        return m_line_cache[peekLine].m_line[peekLineOffset];
+    }
+
+    _NODISCARD const ParserLine& CurrentLine() const
+    {
+        return m_line_cache[m_line_index];
     }
 
     _NODISCARD bool IsLineEnd() const
     {
-        return m_current_line_offset >= m_current_line.m_line.size();
+        return m_current_line_offset >= CurrentLine().m_line.size();
     }
 
     _NODISCARD bool NextCharInLineIs(const char c)
@@ -99,18 +99,20 @@ protected:
 
     _NODISCARD TokenPos GetPreviousCharacterPos() const
     {
-        return TokenPos(m_current_line.m_filename, m_current_line.m_line_number, m_current_line_offset);
+        const auto& currentLine = CurrentLine();
+        return TokenPos(currentLine.m_filename, currentLine.m_line_number, m_current_line_offset);
     }
 
     _NODISCARD TokenPos GetNextCharacterPos()
     {
-        if (m_current_line_offset + 1 >= m_current_line.m_line.size())
+        const auto& currentLine = CurrentLine();
+        if (m_current_line_offset + 1 >= currentLine.m_line.size())
         {
             PeekChar();
-            return TokenPos(m_next_line.m_filename, m_next_line.m_line_number, 1);
+            return TokenPos(m_line_cache.back().m_filename, m_line_cache.back().m_line_number, 1);
         }
 
-        return TokenPos(m_current_line.m_filename, m_current_line.m_line_number, m_current_line_offset + 1);
+        return TokenPos(currentLine.m_filename, currentLine.m_line_number, m_current_line_offset + 1);
     }
 
     /**
@@ -119,14 +121,15 @@ protected:
      */
     std::string ReadIdentifier()
     {
+        const auto& currentLine = CurrentLine();
         assert(m_current_line_offset >= 1);
-        assert(isalpha(m_current_line.m_line[m_current_line_offset - 1]) || m_current_line.m_line[m_current_line_offset - 1] == '_');
+        assert(isalpha(currentLine.m_line[m_current_line_offset - 1]) || currentLine.m_line[m_current_line_offset - 1] == '_');
 
         const auto startPos = m_current_line_offset - 1;
-        const auto lineSize = m_current_line.m_line.size();
+        const auto lineSize = currentLine.m_line.size();
         while (m_current_line_offset < lineSize)
         {
-            const auto c = m_current_line.m_line[m_current_line_offset];
+            const auto c = currentLine.m_line[m_current_line_offset];
 
             if (!isalnum(c) && c != '_')
                 break;
@@ -134,7 +137,7 @@ protected:
             m_current_line_offset++;
         }
 
-        return std::string(m_current_line.m_line, startPos, m_current_line_offset - startPos);
+        return std::string(currentLine.m_line, startPos, m_current_line_offset - startPos);
     }
 
     /**
@@ -143,28 +146,30 @@ protected:
      */
     std::string ReadString()
     {
+        const auto& currentLine = CurrentLine();
         assert(m_current_line_offset >= 1);
-        assert(m_current_line.m_line[m_current_line_offset - 1] == '"');
+        assert(currentLine.m_line[m_current_line_offset - 1] == '"');
 
         const auto startPos = m_current_line_offset;
-        const auto lineSize = m_current_line.m_line.size();
+        const auto lineSize = currentLine.m_line.size();
         while (true)
         {
             if (m_current_line_offset >= lineSize)
-                throw ParsingException(TokenPos(m_current_line.m_filename, m_current_line.m_line_number, m_current_line_offset), "Unclosed string");
+                throw ParsingException(TokenPos(currentLine.m_filename, currentLine.m_line_number, m_current_line_offset), "Unclosed string");
 
-            if (m_current_line.m_line[m_current_line_offset] == '\"')
+            if (currentLine.m_line[m_current_line_offset] == '\"')
                 break;
 
             m_current_line_offset++;
         }
 
-        return std::string(m_current_line.m_line, startPos, m_current_line_offset++ - startPos);
+        return std::string(currentLine.m_line, startPos, m_current_line_offset++ - startPos);
     }
 
     void ReadHexNumber(int& integerValue)
     {
-        const auto* start = &m_current_line.m_line.c_str()[m_current_line_offset - 1];
+        const auto& currentLine = CurrentLine();
+        const auto* start = &currentLine.m_line.c_str()[m_current_line_offset - 1];
         char* end;
 
         integerValue = static_cast<int>(std::strtoul(start, &end, 16));
@@ -177,7 +182,8 @@ protected:
 
     _NODISCARD bool IsIntegerNumber() const
     {
-        const auto* currentCharacter = &m_current_line.m_line.c_str()[m_current_line_offset - 1];
+        const auto& currentLine = CurrentLine();
+        const auto* currentCharacter = &currentLine.m_line.c_str()[m_current_line_offset - 1];
         auto isInteger = true;
         auto dot = false;
         auto exponent = false;
@@ -223,7 +229,8 @@ protected:
 
     int ReadInteger()
     {
-        const auto* start = &m_current_line.m_line.c_str()[m_current_line_offset - 1];
+        const auto& currentLine = CurrentLine();
+        const auto* start = &currentLine.m_line.c_str()[m_current_line_offset - 1];
         char* end;
         const auto integerValue = std::strtol(start, &end, 10);
         const auto numberLength = static_cast<unsigned>(end - start);
@@ -238,7 +245,8 @@ protected:
 
     double ReadFloatingPoint()
     {
-        const auto* start = &m_current_line.m_line.c_str()[m_current_line_offset - 1];
+        const auto& currentLine = CurrentLine();
+        const auto* start = &currentLine.m_line.c_str()[m_current_line_offset - 1];
         char* end;
         const auto floatingPointValue = std::strtod(start, &end);
         const auto numberLength = static_cast<unsigned>(end - start);
@@ -253,13 +261,14 @@ protected:
 
     void ReadNumber(bool& isFloatingPoint, double& floatingPointValue, int& integerValue)
     {
+        const auto& currentLine = CurrentLine();
         assert(m_current_line_offset >= 1);
-        assert(isdigit(m_current_line.m_line[m_current_line_offset - 1]));
+        assert(isdigit(currentLine.m_line[m_current_line_offset - 1]));
 
-        const auto lineLength = m_current_line.m_line.size();
+        const auto lineLength = currentLine.m_line.size();
         if (lineLength - m_current_line_offset >= 1
-            && m_current_line.m_line[m_current_line_offset - 1] == '0'
+            && currentLine.m_line[m_current_line_offset - 1] == '0'
-            && m_current_line.m_line[m_current_line_offset] == 'x')
+            && currentLine.m_line[m_current_line_offset] == 'x')
         {
             isFloatingPoint = false;
             ReadHexNumber(integerValue);
@@ -287,8 +296,32 @@ public:
     }
 
     void PopTokens(int amount) override
+    {
+        if (amount <= 0 || m_token_cache.empty())
+            return;
+
+        if (static_cast<int>(m_token_cache.size()) <= amount)
+        {
+            const auto& lastToken = m_token_cache.back();
+            while (m_line_cache.front().m_line_number != lastToken.GetPos().m_line
+                || m_line_cache.front().m_filename.get() != lastToken.GetPos().m_filename.get())
+            {
+                m_line_cache.pop_front();
+                m_line_index--;
+            }
+            m_token_cache.clear();
+        }
+        else
         {
             m_token_cache.erase(m_token_cache.begin(), m_token_cache.begin() + amount);
+            const auto& firstToken = m_token_cache.front();
+            while (m_line_cache.front().m_line_number != firstToken.GetPos().m_line
+                || m_line_cache.front().m_filename.get() != firstToken.GetPos().m_filename.get())
+            {
+                m_line_cache.pop_front();
+                m_line_index--;
+            }
+        }
     }
 
     _NODISCARD bool IsEof() override
@@ -300,4 +333,16 @@ public:
     {
         return GetToken(0).GetPos();
     }
+
+    _NODISCARD ParserLine GetLineForPos(const TokenPos& pos) const override
+    {
+        for(const auto& line : m_line_cache)
+        {
+            if (line.m_filename.get() == pos.m_filename.get()
+                && line.m_line_number == pos.m_line)
+                return line;
+        }
+
+        return ParserLine();
+    }
 };

src/ZoneCodeGeneratorLib/Parsing/Impl/AbstractParser.h

@@ -60,7 +60,17 @@ public:
                 if (!testSuccessful)
                 {
                     const TokenPos& pos = m_lexer->GetPos();
-                    std::cout << "Error: " << pos.m_filename << " L" << pos.m_line << ':' << pos.m_column << " Could not parse expression." << std::endl;
+                    const ParserLine line = m_lexer->GetLineForPos(pos);
+
+                    if (!line.IsEof())
+                    {
+                        std::cout << "Error: " << pos.m_filename.get() << " L" << pos.m_line << ':' << pos.m_column << " Could not parse expression:\n"
+                            << line.m_line.substr(pos.m_column - 1) << std::endl;
+                    }
+                    else
+                    {
+                        std::cout << "Error: " << pos.m_filename.get() << " L" << pos.m_line << ':' << pos.m_column << " Could not parse expression." << std::endl;
+                    }
                     return false;
                 }
             }

src/ZoneCodeGeneratorLib/Parsing/Impl/CommentRemovingStreamProxy.cpp

@@ -63,6 +63,11 @@ bool CommentRemovingStreamProxy::IncludeFile(const std::string& filename)
     return m_stream->IncludeFile(filename);
 }
 
+void CommentRemovingStreamProxy::PopCurrentFile()
+{
+    m_stream->PopCurrentFile();
+}
+
 bool CommentRemovingStreamProxy::IsOpen() const
 {
     return m_stream->IsOpen();

src/ZoneCodeGeneratorLib/Parsing/Impl/CommentRemovingStreamProxy.h

@@ -13,6 +13,7 @@ public:
 
     ParserLine NextLine() override;
     bool IncludeFile(const std::string& filename) override;
+    void PopCurrentFile() override;
     _NODISCARD bool IsOpen() const override;
     _NODISCARD bool Eof() const override;
 };

src/ZoneCodeGeneratorLib/Parsing/Impl/DefinesStreamProxy.cpp

@@ -290,6 +290,11 @@ bool DefinesStreamProxy::IncludeFile(const std::string& filename)
     return m_stream->IncludeFile(filename);
 }
 
+void DefinesStreamProxy::PopCurrentFile()
+{
+    m_stream->PopCurrentFile();
+}
+
 bool DefinesStreamProxy::IsOpen() const
 {
     return m_stream->IsOpen();

src/ZoneCodeGeneratorLib/Parsing/Impl/DefinesStreamProxy.h

@@ -38,6 +38,7 @@ public:
 
     ParserLine NextLine() override;
     bool IncludeFile(const std::string& filename) override;
+    void PopCurrentFile() override;
     _NODISCARD bool IsOpen() const override;
     _NODISCARD bool Eof() const override;
 };

src/ZoneCodeGeneratorLib/Parsing/Impl/IncludingStreamProxy.cpp

@@ -1,38 +1,17 @@
 #include "IncludingStreamProxy.h"
 
 #include <sstream>
+#include <filesystem>
 
 #include "Parsing/ParsingException.h"
 
+namespace fs = std::filesystem;
+
 IncludingStreamProxy::IncludingStreamProxy(IParserLineStream* stream)
     : m_stream(stream)
 {
 }
 
-bool IncludingStreamProxy::FindIncludeDirective(const ParserLine& line, unsigned& includeDirectivePosition)
-{
-    includeDirectivePosition = 0;
-    for (; includeDirectivePosition < line.m_line.size() - INCLUDE_DIRECTIVE_MINIMUM_TOTAL_LENGTH; includeDirectivePosition++)
-    {
-        const auto c = line.m_line[includeDirectivePosition];
-
-        if (isspace(c))
-            continue;
-
-        if (c != '#')
-            return false;
-
-        if (line.m_line.compare(includeDirectivePosition + 1, INCLUDE_DIRECTIVE_LENGTH, INCLUDE_DIRECTIVE) != 0)
-        {
-            return false;
-        }
-
-        return true;
-    }
-
-    return false;
-}
-
 bool IncludingStreamProxy::ExtractIncludeFilename(const ParserLine& line, const unsigned includeDirectivePosition, unsigned& filenameStartPosition, unsigned& filenameEndPosition)
 {
     auto currentPos = includeDirectivePosition;
@@ -78,14 +57,13 @@ bool IncludingStreamProxy::ExtractIncludeFilename(const ParserLine& line, const
     return false;
 }
 
-bool IncludingStreamProxy::MatchIncludeDirective(const ParserLine& line) const
+bool IncludingStreamProxy::MatchIncludeDirective(const ParserLine& line, const unsigned directivePosition) const
 {
-    unsigned includeDirectivePos;
+    constexpr auto directiveLength = std::char_traits<char>::length(INCLUDE_DIRECTIVE);
-
+    if (line.m_line.compare(directivePosition + 1, directiveLength, INCLUDE_DIRECTIVE) != 0)
-    if (!FindIncludeDirective(line, includeDirectivePos))
         return false;
 
-    const auto currentPos = includeDirectivePos + INCLUDE_DIRECTIVE_LENGTH + 1;
+    const auto currentPos = directivePosition + directiveLength + 1;
     unsigned filenameStart, filenameEnd;
 
     if (!ExtractIncludeFilename(line, currentPos, filenameStart, filenameEnd))
@@ -106,12 +84,57 @@ bool IncludingStreamProxy::MatchIncludeDirective(const ParserLine& line) const
     return true;
 }
 
+bool IncludingStreamProxy::MatchPragmaOnceDirective(const ParserLine& line, const unsigned directivePosition)
+{
+    constexpr auto directiveLength = std::char_traits<char>::length(PRAGMA_ONCE_DIRECTIVE);
+    if (line.m_line.compare(directivePosition + 1, directiveLength, PRAGMA_ONCE_DIRECTIVE) != 0)
+        return false;
+
+    const auto absolutePath = absolute(fs::path(line.m_filename.get()));
+    const auto absolutePathStr = absolutePath.string();
+
+    const auto existingPath = m_included_files.find(absolutePathStr);
+    if (existingPath != m_included_files.end())
+        m_stream->PopCurrentFile();
+    else
+        m_included_files.emplace(absolutePathStr);
+
+    return true;
+}
+
+bool IncludingStreamProxy::FindDirective(const ParserLine& line, unsigned& directivePosition)
+{
+    directivePosition = 0;
+    for (; directivePosition < line.m_line.size(); directivePosition++)
+    {
+        const auto c = line.m_line[directivePosition];
+
+        if (isspace(c))
+            continue;
+
+        return c == '#';
+    }
+
+    return false;
+}
+
+bool IncludingStreamProxy::MatchDirectives(const ParserLine& line)
+{
+    unsigned directivePos;
+
+    if (!FindDirective(line, directivePos))
+        return false;
+
+    return MatchIncludeDirective(line, directivePos)
+        || MatchPragmaOnceDirective(line, directivePos);
+}
+
 ParserLine IncludingStreamProxy::NextLine()
 {
     auto line = m_stream->NextLine();
 
-    if (MatchIncludeDirective(line))
+    while(MatchDirectives(line))
-        return m_stream->NextLine();
+        line = m_stream->NextLine();
 
     return line;
 }
@@ -121,6 +144,11 @@ bool IncludingStreamProxy::IncludeFile(const std::string& filename)
     return m_stream->IncludeFile(filename);
 }
 
+void IncludingStreamProxy::PopCurrentFile()
+{
+    m_stream->PopCurrentFile();
+}
+
 bool IncludingStreamProxy::IsOpen() const
 {
     return m_stream->IsOpen();

src/ZoneCodeGeneratorLib/Parsing/Impl/IncludingStreamProxy.h

@@ -1,25 +1,31 @@
 #pragma once
 
+#include <set>
+
 #include "Parsing/IParserLineStream.h"
 
 class IncludingStreamProxy final : public IParserLineStream
 {
     static constexpr const char* INCLUDE_QUOTES_ERROR = "Invalid include directive. Expected \"\" or <>";
     static constexpr const char* INCLUDE_DIRECTIVE = "include ";
-    static constexpr int INCLUDE_DIRECTIVE_LENGTH = std::char_traits<char>::length(INCLUDE_DIRECTIVE);
+    static constexpr const char* PRAGMA_ONCE_DIRECTIVE = "pragma once";
-    static constexpr int INCLUDE_DIRECTIVE_MINIMUM_TOTAL_LENGTH = INCLUDE_DIRECTIVE_LENGTH + 1 + 2; // #=+1 ""=+2
 
     IParserLineStream* const m_stream;
+    std::set<std::string> m_included_files;
+
     
-    _NODISCARD static bool FindIncludeDirective(const ParserLine& line, unsigned& includeDirectivePosition);
     _NODISCARD static bool ExtractIncludeFilename(const ParserLine& line, unsigned includeDirectivePosition, unsigned& filenameStartPosition, unsigned& filenameEndPosition);
-    _NODISCARD bool MatchIncludeDirective(const ParserLine& line) const;
+    _NODISCARD bool MatchIncludeDirective(const ParserLine& line, unsigned directivePosition) const;
+    _NODISCARD bool MatchPragmaOnceDirective(const ParserLine& line, unsigned directivePosition);
+    _NODISCARD static bool FindDirective(const ParserLine& line, unsigned& directivePosition);
+    _NODISCARD bool MatchDirectives(const ParserLine& line);
 
 public:
     explicit IncludingStreamProxy(IParserLineStream* stream);
 
     ParserLine NextLine() override;
     bool IncludeFile(const std::string& filename) override;
+    void PopCurrentFile() override;
     _NODISCARD bool IsOpen() const override;
     _NODISCARD bool Eof() const override;
 };

src/ZoneCodeGeneratorLib/Parsing/Impl/ParserFilesystemStream.cpp

@@ -14,7 +14,8 @@ ParserFilesystemStream::FileInfo::FileInfo(std::string filePath)
 
 ParserFilesystemStream::ParserFilesystemStream(std::string path)
 {
-    m_files.emplace(FileInfo(std::move(path)));
+    const auto absolutePath = absolute(fs::path(path));
+    m_files.emplace(FileInfo(absolutePath.string()));
 }
 
 bool ParserFilesystemStream::IsOpen() const
@@ -75,6 +76,7 @@ bool ParserFilesystemStream::IncludeFile(const std::string& filename)
     
     auto newFilePath = fs::path(m_files.top().m_file_path);
     newFilePath.remove_filename().concat(filename);
+    newFilePath = absolute(newFilePath);
 
     FileInfo fileInfo(newFilePath.string());
 
@@ -85,6 +87,12 @@ bool ParserFilesystemStream::IncludeFile(const std::string& filename)
     return true;
 }
 
+void ParserFilesystemStream::PopCurrentFile()
+{
+    if(!m_files.empty())
+        m_files.pop();
+}
+
 bool ParserFilesystemStream::Eof() const
 {
     return m_files.empty()

src/ZoneCodeGeneratorLib/Parsing/Impl/ParserFilesystemStream.h

@@ -23,6 +23,7 @@ public:
 
     ParserLine NextLine() override;
     bool IncludeFile(const std::string& filename) override;
+    void PopCurrentFile() override;
     _NODISCARD bool IsOpen() const override;
     _NODISCARD bool Eof() const override;
 };

src/ZoneCodeGeneratorLib/Parsing/ParsingException.cpp

@@ -7,7 +7,7 @@ ParsingException::ParsingException(const TokenPos position, std::string message)
       m_message(std::move(message))
 {
     std::ostringstream str;
-    str << position.m_filename << " L" << m_pos.m_line << ':' << m_pos.m_column << ' ' << m_message;
+    str << position.m_filename.get() << " L" << m_pos.m_line << ':' << m_pos.m_column << ' ' << m_message;
     m_full_message = str.str();
 }
 

src/ZoneCodeGeneratorLib/Parsing/TokenPos.h

@@ -7,7 +7,7 @@ class TokenPos
     static const std::string EMPTY_FILENAME;
 
 public:
-    const std::string& m_filename;
+    std::reference_wrapper<const std::string> m_filename;
     int m_line;
     int m_column;
 

test/ZoneCodeGeneratorLibTests/Parsing/Impl/IncludingStreamProxyTest.cpp

@@ -133,4 +133,49 @@ namespace test::parsing::impl::including_stream_proxy
 
         REQUIRE(proxy.Eof());
     }
+
+    TEST_CASE("IncludingStreamProxy: Ensure pragma once prevents including the same file more than once", "[parsing][parsingstream]")
+    {
+        const std::vector<std::string> lines
+        {
+            "Hello world",
+            "#include \"ASDF.txt\"",
+            "#include \"ASDF.txt\"",
+            "and bye"
+        };
+
+        const std::vector<std::string> asdf
+        {
+            "#pragma once",
+            "Hello galaxy"
+        };
+
+        MockParserLineStream mockStream(lines);
+        mockStream.AddIncludeLines("ASDF.txt", asdf);
+
+        IncludingStreamProxy proxy(&mockStream);
+
+        {
+            auto line = proxy.NextLine();
+            REQUIRE(line.m_line_number == 1);
+            REQUIRE(line.m_filename.get() == MockParserLineStream::MOCK_FILENAME);
+            REQUIRE(line.m_line == "Hello world");
+        }
+
+        {
+            auto line = proxy.NextLine();
+            REQUIRE(line.m_line_number == 2);
+            REQUIRE(line.m_filename.get() == "ASDF.txt");
+            REQUIRE(line.m_line == "Hello galaxy");
+        }
+
+        {
+            auto line = proxy.NextLine();
+            REQUIRE(line.m_line_number == 4);
+            REQUIRE(line.m_filename.get() == MockParserLineStream::MOCK_FILENAME);
+            REQUIRE(line.m_line == "and bye");
+        }
+
+        REQUIRE(proxy.Eof());
+    }
 }

test/ZoneCodeGeneratorLibTests/Parsing/Mock/MockParserLineStream.cpp

@@ -50,6 +50,12 @@ bool MockParserLineStream::IncludeFile(const std::string& filename)
     return true;
 }
 
+void MockParserLineStream::PopCurrentFile()
+{
+    if (!m_include_positions.empty())
+        m_include_positions.pop_back();
+}
+
 bool MockParserLineStream::IsOpen() const
 {
     return true;

test/ZoneCodeGeneratorLibTests/Parsing/Mock/MockParserLineStream.h

@@ -30,6 +30,7 @@ public:
     void AddIncludeLines(const std::string& filename, const std::vector<std::string>& lines);
     ParserLine NextLine() override;
     bool IncludeFile(const std::string& filename) override;
+    void PopCurrentFile() override;
     _NODISCARD bool IsOpen() const override;
     _NODISCARD bool Eof() const override;
 };