Instead of deriving different tokens from a base Token class, we now use an enumerated TOKEN_TYPE to distinguish types. This is so we don't have to cast all the time when parsing the resulting token stream.

Also, removed start/end stream tokens.

parser.cpp

@@ -8,9 +8,6 @@ namespace YAML
 {
 	Parser::Parser(std::istream& in): m_scanner(in)
 	{
-		// eat the stream start token
-		// TODO: check?
-		Token *pToken = m_scanner.GetNextToken();
 	}
 
 	Parser::~Parser()
@@ -25,7 +22,7 @@ namespace YAML
 			if(!pToken)
 				break;
 
-			std::cout << typeid(*pToken).name() << ": " << *pToken << std::endl;
+			std::cout << *pToken << std::endl;
 			delete pToken;
 		}
 		getchar();

scanner.cpp

@@ -16,10 +16,6 @@ namespace YAML
 			delete m_tokens.front();
 			m_tokens.pop();
 		}
-
-		// delete limbo tokens (they're here for RAII)
-		for(std::set <Token *>::const_iterator it=m_limboTokens.begin();it!=m_limboTokens.end();++it)
-			delete *it;
 	}
 
 	// GetNextToken
@@ -78,7 +74,7 @@ namespace YAML
 			return;
 
 		if(!m_startedStream)
-			return ScanAndEnqueue(new StreamStartToken);
+			return StartStream();
 
 		// get rid of whitespace, etc. (in between tokens it should be irrelevent)
 		ScanToNextToken();
@@ -95,62 +91,56 @@ namespace YAML
 
 		// end of stream
 		if(INPUT.peek() == EOF)
-			return ScanAndEnqueue(new StreamEndToken);
+			return EndStream();
 
 		if(INPUT.column == 0 && INPUT.peek() == Keys::Directive)
-			return ScanAndEnqueue(new DirectiveToken);
+			return ScanDirective();
 
 		// document token
 		if(INPUT.column == 0 && Exp::DocStart.Matches(INPUT))
-			return ScanAndEnqueue(new DocumentStartToken);
+			return ScanDocStart();
 
 		if(INPUT.column == 0 && Exp::DocEnd.Matches(INPUT))
-			return ScanAndEnqueue(new DocumentEndToken);
+			return ScanDocEnd();
 
 		// flow start/end/entry
-		if(INPUT.peek() == Keys::FlowSeqStart)
+		if(INPUT.peek() == Keys::FlowSeqStart || INPUT.peek() == Keys::FlowMapStart)
-			return ScanAndEnqueue(new FlowSeqStartToken);
+			return ScanFlowStart();
 
-		if(INPUT.peek() == Keys::FlowSeqEnd)
+		if(INPUT.peek() == Keys::FlowSeqEnd || INPUT.peek() == Keys::FlowMapEnd)
-			return ScanAndEnqueue(new FlowSeqEndToken);
+			return ScanFlowEnd();
-		
-		if(INPUT.peek() == Keys::FlowMapStart)
-			return ScanAndEnqueue(new FlowMapStartToken);
-		
-		if(INPUT.peek() == Keys::FlowMapEnd)
-			return ScanAndEnqueue(new FlowMapEndToken);
 	
 		if(INPUT.peek() == Keys::FlowEntry)
-			return ScanAndEnqueue(new FlowEntryToken);
+			return ScanFlowEntry();
 
 		// block/map stuff
 		if(Exp::BlockEntry.Matches(INPUT))
-			return ScanAndEnqueue(new BlockEntryToken);
+			return ScanBlockEntry();
 
 		if((m_flowLevel == 0 ? Exp::Key : Exp::KeyInFlow).Matches(INPUT))
-			return ScanAndEnqueue(new KeyToken);
+			return ScanKey();
 
 		if((m_flowLevel == 0 ? Exp::Value : Exp::ValueInFlow).Matches(INPUT))
-			return ScanAndEnqueue(new ValueToken);
+			return ScanValue();
 
 		// alias/anchor
 		if(INPUT.peek() == Keys::Alias || INPUT.peek() == Keys::Anchor)
-			return ScanAndEnqueue(new AnchorToken);
+			return ScanAnchorOrAlias();
 
 		// tag
 		if(INPUT.peek() == Keys::Tag)
-			return ScanAndEnqueue(new TagToken);
+			return ScanTag();
 
 		// special scalars
 		if(m_flowLevel == 0 && (INPUT.peek() == Keys::LiteralScalar || INPUT.peek() == Keys::FoldedScalar))
-			return ScanAndEnqueue(new BlockScalarToken);
+			return ScanBlockScalar();
 
 		if(INPUT.peek() == '\'' || INPUT.peek() == '\"')
-			return ScanAndEnqueue(new QuotedScalarToken);
+			return ScanQuotedScalar();
 
 		// plain scalars
 		if((m_flowLevel == 0 ? Exp::PlainScalar : Exp::PlainScalarInFlow).Matches(INPUT))
-			return ScanAndEnqueue(new PlainScalarToken);
+			return ScanPlainScalar();
 
 		// don't know what it is!
 		throw UnknownToken();
@@ -210,18 +200,28 @@ namespace YAML
 		return false;
 	}
 
-	// ScanAndEnqueue
+	// StartStream
-	// . Scans the token, then pushes it in the queue.
+	// . Set the initial conditions for starting a stream.
-	// . Note: we also use a set of "limbo tokens", i.e., tokens
+	void Scanner::StartStream()
-	//   that haven't yet been pushed. This way, if ScanToken()
-	//   throws an exception, we'll be keeping track of 'pToken'
-	//   somewhere, and it will be automatically cleaned up when
-	//   the Scanner destructs.
-	template <typename T> void Scanner::ScanAndEnqueue(T *pToken)
 	{
-		m_limboTokens.insert(pToken);
+		m_startedStream = true;
-		m_tokens.push(ScanToken(pToken));
+		m_simpleKeyAllowed = true;
-		m_limboTokens.erase(pToken);
+		m_indents.push(-1);
+	}
+
+	// EndStream
+	// . Close out the stream, finish up, etc.
+	void Scanner::EndStream()
+	{
+		// force newline
+		if(INPUT.column > 0)
+			INPUT.column = 0;
+
+		PopIndentTo(-1);
+		VerifyAllSimpleKeys();
+
+		m_simpleKeyAllowed = false;
+		m_endedStream = true;
 	}
 
 	// PushIndentTo
@@ -241,9 +241,9 @@ namespace YAML
 		// now push
 		m_indents.push(column);
 		if(sequence)
-			m_tokens.push(new BlockSeqStartToken);
+			m_tokens.push(new Token(TT_BLOCK_SEQ_START));
 		else
-			m_tokens.push(new BlockMapStartToken);
+			m_tokens.push(new Token(TT_BLOCK_MAP_START));
 
 		return m_tokens.front();
 	}
@@ -260,7 +260,7 @@ namespace YAML
 		// now pop away
 		while(!m_indents.empty() && m_indents.top() > column) {
 			m_indents.pop();
-			m_tokens.push(new BlockEndToken);
+			m_tokens.push(new Token(TT_BLOCK_END));
 		}
 	}
 }

scanner.h

@@ -23,6 +23,8 @@ namespace YAML
 
 	private:
 		// scanning
+		void StartStream();
+		void EndStream();
 		void ScanNextToken();
 		void ScanToNextToken();
 		Token *PushIndentTo(int column, bool sequence);
@@ -46,8 +48,24 @@ namespace YAML
 			Token *pMapStart, *pKey;
 		};
 
-		template <typename T> void ScanAndEnqueue(T *pToken);
+		// and the tokens
-		template <typename T> T *ScanToken(T *pToken);
+		void ScanDirective();
+		void ScanDocStart();
+		void ScanDocEnd();
+		void ScanBlockSeqStart();
+		void ScanBlockMapSTart();
+		void ScanBlockEnd();
+		void ScanBlockEntry();
+		void ScanFlowStart();
+		void ScanFlowEnd();
+		void ScanFlowEntry();
+		void ScanKey();
+		void ScanValue();
+		void ScanAnchorOrAlias();
+		void ScanTag();
+		void ScanPlainScalar();
+		void ScanQuotedScalar();
+		void ScanBlockScalar();
 
 	private:
 		// the stream
@@ -55,7 +73,6 @@ namespace YAML
 
 		// the output (tokens)
 		std::queue <Token *> m_tokens;
-		std::set <Token *> m_limboTokens;
 
 		// state info
 		bool m_startedStream, m_endedStream;

scantoken.cpp

@@ -9,36 +9,13 @@ namespace YAML
 	///////////////////////////////////////////////////////////////////////
 	// Specialization for scanning specific tokens
 
-	// StreamStartToken
+	// Directive
-	template <> StreamStartToken *Scanner::ScanToken(StreamStartToken *pToken)
-	{
-		m_startedStream = true;
-		m_simpleKeyAllowed = true;
-		m_indents.push(-1);
-
-		return pToken;
-	}
-
-	// StreamEndToken
-	template <> StreamEndToken *Scanner::ScanToken(StreamEndToken *pToken)
-	{
-		// force newline
-		if(INPUT.column > 0)
-			INPUT.column = 0;
-
-		PopIndentTo(-1);
-		VerifyAllSimpleKeys();
-
-		m_simpleKeyAllowed = false;
-		m_endedStream = true;
-
-		return pToken;
-	}
-
-	// DirectiveToken
 	// . Note: no semantic checking is done here (that's for the parser to do)
-	template <> DirectiveToken *Scanner::ScanToken(DirectiveToken *pToken)
+	void Scanner::ScanDirective()
 	{
+		std::string name;
+		std::vector <std::string> params;
+
 		// pop indents and simple keys
 		PopIndentTo(-1);
 		VerifyAllSimpleKeys();
@@ -50,7 +27,7 @@ namespace YAML
 
 		// read name
 		while(INPUT.peek() != EOF && !Exp::BlankOrBreak.Matches(INPUT))
-			pToken->name += INPUT.GetChar();
+			name += INPUT.GetChar();
 
 		// read parameters
 		while(1) {
@@ -67,14 +44,17 @@ namespace YAML
 			while(INPUT.peek() != EOF && !Exp::BlankOrBreak.Matches(INPUT))
 				param += INPUT.GetChar();
 
-			pToken->params.push_back(param);
+			params.push_back(param);
 		}
 		
-		return pToken;
+		Token *pToken = new Token(TT_DIRECTIVE);
+		pToken->value = name;
+		pToken->params = params;
+		m_tokens.push(pToken);
 	}
 
-	// DocumentStartToken
+	// DocStart
-	template <> DocumentStartToken *Scanner::ScanToken(DocumentStartToken *pToken)
+	void Scanner::ScanDocStart()
 	{
 		PopIndentTo(INPUT.column);
 		VerifyAllSimpleKeys();
@@ -82,11 +62,11 @@ namespace YAML
 
 		// eat
 		INPUT.Eat(3);
-		return pToken;
+		m_tokens.push(new Token(TT_DOC_START));
 	}
 
-	// DocumentEndToken
+	// DocEnd
-	template <> DocumentEndToken *Scanner::ScanToken(DocumentEndToken *pToken)
+	void Scanner::ScanDocEnd()
 	{
 		PopIndentTo(-1);
 		VerifyAllSimpleKeys();
@@ -94,37 +74,25 @@ namespace YAML
 
 		// eat
 		INPUT.Eat(3);
-		return pToken;
+		m_tokens.push(new Token(TT_DOC_END));
 	}
 
-	// FlowSeqStartToken
+	// FlowStart
-	template <> FlowSeqStartToken *Scanner::ScanToken(FlowSeqStartToken *pToken)
+	void Scanner::ScanFlowStart()
 	{
-		// flow sequences can be simple keys
+		// flows can be simple keys
 		InsertSimpleKey();
 		m_flowLevel++;
 		m_simpleKeyAllowed = true;
 
 		// eat
-		INPUT.Eat(1);
+		char ch = INPUT.GetChar();
-		return pToken;
+		TOKEN_TYPE type = (ch == Keys::FlowSeqStart ? TT_FLOW_SEQ_START : TT_FLOW_MAP_START);
+		m_tokens.push(new Token(type));
 	}
 
-	// FlowMapStartToken
+	// FlowEnd
-	template <> FlowMapStartToken *Scanner::ScanToken(FlowMapStartToken *pToken)
+	void Scanner::ScanFlowEnd()
-	{
-		// flow maps can be simple keys
-		InsertSimpleKey();
-		m_flowLevel++;
-		m_simpleKeyAllowed = true;
-
-		// eat
-		INPUT.Eat(1);
-		return pToken;
-	}
-
-	// FlowSeqEndToken
-	template <> FlowSeqEndToken *Scanner::ScanToken(FlowSeqEndToken *pToken)
 	{
 		if(m_flowLevel == 0)
 			throw IllegalFlowEnd();
@@ -133,36 +101,23 @@ namespace YAML
 		m_simpleKeyAllowed = false;
 
 		// eat
-		INPUT.Eat(1);
+		char ch = INPUT.GetChar();
-		return pToken;
+		TOKEN_TYPE type = (ch == Keys::FlowSeqEnd ? TT_FLOW_SEQ_END : TT_FLOW_MAP_END);
+		m_tokens.push(new Token(type));
 	}
 
-	// FlowMapEndToken
+	// FlowEntry
-	template <> FlowMapEndToken *Scanner::ScanToken(FlowMapEndToken *pToken)
+	void Scanner::ScanFlowEntry()
-	{
-		if(m_flowLevel == 0)
-			throw IllegalFlowEnd();
-
-		m_flowLevel--;
-		m_simpleKeyAllowed = false;
-
-		// eat
-		INPUT.Eat(1);
-		return pToken;
-	}
-
-	// FlowEntryToken
-	template <> FlowEntryToken *Scanner::ScanToken(FlowEntryToken *pToken)
 	{
 		m_simpleKeyAllowed = true;
 
 		// eat
 		INPUT.Eat(1);
-		return pToken;
+		m_tokens.push(new Token(TT_FLOW_ENTRY));
 	}
 
-	// BlockEntryToken
+	// BlockEntry
-	template <> BlockEntryToken *Scanner::ScanToken(BlockEntryToken *pToken)
+	void Scanner::ScanBlockEntry()
 	{
 		// we better be in the block context!
 		if(m_flowLevel > 0)
@@ -177,11 +132,11 @@ namespace YAML
 
 		// eat
 		INPUT.Eat(1);
-		return pToken;
+		m_tokens.push(new Token(TT_BLOCK_ENTRY));
 	}
 
-	// KeyToken
+	// Key
-	template <> KeyToken *Scanner::ScanToken(KeyToken *pToken)
+	void Scanner::ScanKey()
 	{
 		// handle keys diffently in the block context (and manage indents)
 		if(m_flowLevel == 0) {
@@ -199,11 +154,11 @@ namespace YAML
 
 		// eat
 		INPUT.Eat(1);
-		return pToken;
+		m_tokens.push(new Token(TT_KEY));
 	}
 
-	// ValueToken
+	// Value
-	template <> ValueToken *Scanner::ScanToken(ValueToken *pToken)
+	void Scanner::ScanValue()
 	{
 		// does this follow a simple key?
 		if(m_isLastKeyValid) {
@@ -227,12 +182,15 @@ namespace YAML
 
 		// eat
 		INPUT.Eat(1);
-		return pToken;
+		m_tokens.push(new Token(TT_VALUE));
 	}
 
-	// AnchorToken
+	// AnchorOrAlias
-	template <> AnchorToken *Scanner::ScanToken(AnchorToken *pToken)
+	void Scanner::ScanAnchorOrAlias()
 	{
+		bool alias;
+		std::string tag;
+
 		// insert a potential simple key
 		if(m_simpleKeyAllowed)
 			InsertSimpleKey();
@@ -240,10 +198,9 @@ namespace YAML
 
 		// eat the indicator
 		char indicator = INPUT.GetChar();
-		pToken->alias = (indicator == Keys::Alias);
+		alias = (indicator == Keys::Alias);
 
 		// now eat the content
-		std::string tag;
 		while(Exp::AlphaNumeric.Matches(INPUT))
 			tag += INPUT.GetChar();
 
@@ -256,13 +213,16 @@ namespace YAML
 			throw IllegalCharacterInAnchor();
 
 		// and we're done
+		Token *pToken = new Token(alias ? TT_ALIAS : TT_ANCHOR);
 		pToken->value = tag;
-		return pToken;
+		m_tokens.push(pToken);
 	}
 
-	// TagToken
+	// Tag
-	template <> TagToken *Scanner::ScanToken(TagToken *pToken)
+	void Scanner::ScanTag()
 	{
+		std::string handle, suffix;
+
 		// insert a potential simple key
 		if(m_simpleKeyAllowed)
 			InsertSimpleKey();
@@ -273,7 +233,7 @@ namespace YAML
 
 		// read the handle
 		while(INPUT.peek() != EOF && INPUT.peek() != Keys::Tag && !Exp::BlankOrBreak.Matches(INPUT))
-			pToken->handle += INPUT.GetChar();
+			handle += INPUT.GetChar();
 
 		// is there a suffix?
 		if(INPUT.peek() == Keys::Tag) {
@@ -282,15 +242,20 @@ namespace YAML
 
 			// then read it
 			while(INPUT.peek() != EOF && !Exp::BlankOrBreak.Matches(INPUT))
-				pToken->suffix += INPUT.GetChar();
+				suffix += INPUT.GetChar();
 		}
 
-		return pToken;
+		Token *pToken = new Token(TT_TAG);
+		pToken->value = handle;
+		pToken->params.push_back(suffix);
+		m_tokens.push(pToken);
 	}
 
-	// PlainScalarToken
+	// PlainScalar
-	template <> PlainScalarToken *Scanner::ScanToken(PlainScalarToken *pToken)
+	void Scanner::ScanPlainScalar()
 	{
+		std::string scalar;
+
 		// set up the scanning parameters
 		ScanScalarParams params;
 		params.end = (m_flowLevel > 0 ? Exp::EndScalarInFlow : Exp::EndScalar) || (RegEx(' ') + Exp::Comment);
@@ -307,7 +272,7 @@ namespace YAML
 		if(m_simpleKeyAllowed)
 			InsertSimpleKey();
 
-		pToken->value = ScanScalar(INPUT, params);
+		scalar = ScanScalar(INPUT, params);
 
 		// can have a simple key only if we ended the scalar by starting a new line
 		m_simpleKeyAllowed = params.leadingSpaces;
@@ -317,21 +282,25 @@ namespace YAML
 		if(Exp::IllegalColonInScalar.Matches(INPUT))
 			throw IllegalScalar();
 
-		return pToken;
+		Token *pToken = new Token(TT_SCALAR);
+		pToken->value = scalar;
+		m_tokens.push(pToken);
 	}
 
-	// QuotedScalarToken
+	// QuotedScalar
-	template <> QuotedScalarToken *Scanner::ScanToken(QuotedScalarToken *pToken)
+	void Scanner::ScanQuotedScalar()
 	{
+		std::string scalar;
+
 		// eat single or double quote
 		char quote = INPUT.GetChar();
-		pToken->single = (quote == '\'');
+		bool single = (quote == '\'');
 
 		// setup the scanning parameters
 		ScanScalarParams params;
-		params.end = (pToken->single ? RegEx(quote) && !Exp::EscSingleQuote : RegEx(quote));
+		params.end = (single ? RegEx(quote) && !Exp::EscSingleQuote : RegEx(quote));
 		params.eatEnd = true;
-		params.escape = (pToken->single ? '\'' : '\\');
+		params.escape = (single ? '\'' : '\\');
 		params.indent = 0;
 		params.fold = true;
 		params.eatLeadingWhitespace = true;
@@ -343,18 +312,22 @@ namespace YAML
 		if(m_simpleKeyAllowed)
 			InsertSimpleKey();
 
-		pToken->value = ScanScalar(INPUT, params);
+		scalar = ScanScalar(INPUT, params);
 		m_simpleKeyAllowed = false;
 
-		return pToken;
+		Token *pToken = new Token(TT_SCALAR);
+		pToken->value = scalar;
+		m_tokens.push(pToken);
 	}
 
 	// BlockScalarToken
 	// . These need a little extra processing beforehand.
 	// . We need to scan the line where the indicator is (this doesn't count as part of the scalar),
 	//   and then we need to figure out what level of indentation we'll be using.
-	template <> BlockScalarToken *Scanner::ScanToken(BlockScalarToken *pToken)
+	void Scanner::ScanBlockScalar()
 	{
+		std::string scalar;
+
 		ScanScalarParams params;
 		params.indent = 1;
 		params.detectIndent = true;
@@ -401,10 +374,13 @@ namespace YAML
 		params.trimTrailingSpaces = false;
 		params.onTabInIndentation = THROW;
 
-		pToken->value = ScanScalar(INPUT, params);
+		scalar = ScanScalar(INPUT, params);
 
 		// simple keys always ok after block scalars (since we're gonna start a new line anyways)
 		m_simpleKeyAllowed = true;
-		return pToken;
+
+		Token *pToken = new Token(TT_SCALAR);
+		pToken->value = scalar;
+		m_tokens.push(pToken);
 	}
 }

simplekey.cpp

@@ -44,7 +44,7 @@ namespace YAML
 //			key.required = true;	// TODO: is this correct?
 
 		// then add the (now unverified) key
-		key.pKey = new KeyToken;
+		key.pKey = new Token(TT_KEY);
 		key.pKey->status = TS_UNVERIFIED;
 		m_tokens.push(key.pKey);
 

token.h

@@ -7,64 +7,61 @@
 namespace YAML
 {
 	enum TOKEN_STATUS { TS_VALID, TS_INVALID, TS_UNVERIFIED };
+	enum TOKEN_TYPE {
+		TT_DIRECTIVE,
+		TT_DOC_START,
+		TT_DOC_END,
+		TT_BLOCK_SEQ_START,
+		TT_BLOCK_MAP_START,
+		TT_BLOCK_END,
+		TT_BLOCK_ENTRY,
+		TT_FLOW_SEQ_START,
+		TT_FLOW_MAP_START,
+		TT_FLOW_SEQ_END,
+		TT_FLOW_MAP_END,
+		TT_FLOW_ENTRY,
+		TT_KEY,
+		TT_VALUE,
+		TT_ANCHOR,
+		TT_ALIAS,
+		TT_TAG,
+		TT_SCALAR,
+	};
+
+	const std::string TokenNames[] = {
+		"DIRECTIVE",
+		"DOC_START",
+		"DOC_END",
+		"BLOCK_SEQ_START",
+		"BLOCK_MAP_START",
+		"BLOCK_END",
+		"BLOCK_ENTRY",
+		"FLOW_SEQ_START",
+		"FLOW_MAP_START",
+		"FLOW_SEQ_END",
+		"FLOW_MAP_END",
+		"FLOW_ENTRY",
+		"KEY",
+		"VALUE",
+		"ANCHOR",
+		"ALIAS",
+		"TAG",
+		"SCALAR",
+	};
 
 	struct Token {
-		Token(): status(TS_VALID) {}
+		Token(TOKEN_TYPE type_): status(TS_VALID), type(type_) {}
-		virtual ~Token() {}
+
-		virtual void Write(std::ostream& out) const {}
+		friend std::ostream& operator << (std::ostream& out, const Token& token) {
+			out << TokenNames[token.type] << ": " << token.value;
+			for(unsigned i=0;i<token.params.size();i++)
+				out << " " << token.params[i];
+			return out;
+		}
 
-		friend std::ostream& operator << (std::ostream& out, const Token& token) { token.Write(out); return out; }
 		TOKEN_STATUS status;
-	};
+		TOKEN_TYPE type;
-
+		std::string value;
-	struct StreamStartToken: public Token {};
-	struct StreamEndToken: public Token {};
-	struct DirectiveToken: public Token {
-		std::string name;
 		std::vector <std::string> params;
-
-		virtual void Write(std::ostream& out) const { out << name; for(unsigned i=0;i<params.size();i++) out << " " << params[i]; }
 	};
-
-	struct DocumentStartToken: public Token {};
-	struct DocumentEndToken: public Token {};
-
-	struct BlockSeqStartToken: public Token {};
-	struct BlockMapStartToken: public Token {};
-	struct BlockEndToken: public Token {};
-	struct BlockEntryToken: public Token {};
-
-	struct FlowSeqStartToken: public Token {};
-	struct FlowMapStartToken: public Token {};
-	struct FlowSeqEndToken: public Token {};
-	struct FlowMapEndToken: public Token {};
-	struct FlowEntryToken: public Token {};
-
-	struct KeyToken: public Token {};
-	struct ValueToken: public Token {};
-	struct AnchorToken: public Token {
-		bool alias;
-		std::string value;
-
-		virtual void Write(std::ostream& out) const { out << (alias ? '*' : '&') << value; }
-	};
-
-	struct TagToken: public Token {
-		std::string handle, suffix;
-
-		virtual void Write(std::ostream& out) const { out << "!" << handle << "!" << suffix; }
-	};
-
-	struct ScalarToken: public Token {
-		std::string value;
-		virtual void Write(std::ostream& out) const { out << value; }
-	};
-
-	struct PlainScalarToken: public ScalarToken {};
-	struct QuotedScalarToken: public ScalarToken {
-		bool single;
-		virtual void Write(std::ostream& out) const { out << (single ? '\'' : '\"') << value << (single ? '\'' : '\"'); }
-	};
-
-	struct BlockScalarToken: public ScalarToken {};
 }