scantoken.cpp

#include "scanner.h"
#include "token.h"
#include "exceptions.h"
#include "exp.h"

namespace YAML
{
	///////////////////////////////////////////////////////////////////////
	// Specialization for scanning specific tokens

	// StreamStartToken
	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(m_column > 0)
			m_column = 0;

		PopIndentTo(-1);
		ValidateAllSimpleKeys();

		m_simpleKeyAllowed = false;
		m_endedStream = true;

		return pToken;
	}

	// DocumentStartToken
	template <> DocumentStartToken *Scanner::ScanToken(DocumentStartToken *pToken)
	{
		PopIndentTo(m_column);
		ValidateAllSimpleKeys();
		m_simpleKeyAllowed = false;

		// eat
		Eat(3);
		return pToken;
	}

	// DocumentEndToken
	template <> DocumentEndToken *Scanner::ScanToken(DocumentEndToken *pToken)
	{
		PopIndentTo(-1);
		ValidateAllSimpleKeys();
		m_simpleKeyAllowed = false;

		// eat
		Eat(3);
		return pToken;
	}

	// FlowSeqStartToken
	template <> FlowSeqStartToken *Scanner::ScanToken(FlowSeqStartToken *pToken)
	{
		// flow sequences can be simple keys
		InsertSimpleKey();
		m_flowLevel++;
		m_simpleKeyAllowed = true;

		// eat
		Eat(1);
		return pToken;
	}

	// FlowMapStartToken
	template <> FlowMapStartToken *Scanner::ScanToken(FlowMapStartToken *pToken)
	{
		// flow maps can be simple keys
		InsertSimpleKey();
		m_flowLevel++;
		m_simpleKeyAllowed = true;

		// eat
		Eat(1);
		return pToken;
	}

	// FlowSeqEndToken
	template <> FlowSeqEndToken *Scanner::ScanToken(FlowSeqEndToken *pToken)
	{
		if(m_flowLevel == 0)
			throw IllegalFlowEnd();

		m_flowLevel--;
		m_simpleKeyAllowed = false;

		// eat
		Eat(1);
		return pToken;
	}

	// FlowMapEndToken
	template <> FlowMapEndToken *Scanner::ScanToken(FlowMapEndToken *pToken)
	{
		if(m_flowLevel == 0)
			throw IllegalFlowEnd();

		m_flowLevel--;
		m_simpleKeyAllowed = false;

		// eat
		Eat(1);
		return pToken;
	}

	// FlowEntryToken
	template <> FlowEntryToken *Scanner::ScanToken(FlowEntryToken *pToken)
	{
		m_simpleKeyAllowed = true;

		// eat
		Eat(1);
		return pToken;
	}

	// BlockEntryToken
	template <> BlockEntryToken *Scanner::ScanToken(BlockEntryToken *pToken)
	{
		// we better be in the block context!
		if(m_flowLevel > 0)
			throw IllegalBlockEntry();

		// can we put it here?
		if(!m_simpleKeyAllowed)
			throw IllegalBlockEntry();

		PushIndentTo(m_column, true);
		m_simpleKeyAllowed = true;

		// eat
		Eat(1);
		return pToken;
	}

	// KeyToken
	template <> KeyToken *Scanner::ScanToken(KeyToken *pToken)
	{
		// handle keys diffently in the block context (and manage indents)
		if(m_flowLevel == 0) {
			if(!m_simpleKeyAllowed)
				throw IllegalMapKey();

			PushIndentTo(m_column, false);
		}

		// can only put a simple key here if we're in block context
		if(m_flowLevel == 0)
			m_simpleKeyAllowed = true;
		else
			m_simpleKeyAllowed = false;

		// eat
		Eat(1);
		return pToken;
	}

	// ValueToken
	template <> ValueToken *Scanner::ScanToken(ValueToken *pToken)
	{
		// does this follow a simple key?
		if(m_isLastKeyValid) {
			// can't follow a simple key with another simple key (dunno why, though - it seems fine)
			m_simpleKeyAllowed = false;
		} else {
			// handle values diffently in the block context (and manage indents)
			if(m_flowLevel == 0) {
				if(!m_simpleKeyAllowed)
					throw IllegalMapValue();

				PushIndentTo(m_column, false);
			}

			// can only put a simple key here if we're in block context
			if(m_flowLevel == 0)
				m_simpleKeyAllowed = true;
			else
				m_simpleKeyAllowed = false;
		}

		// eat
		Eat(1);
		return pToken;
	}

	// PlainScalarToken
	// . We scan these in passes of two steps each: First, grab all non-whitespace
	//   characters we can, and then grab all whitespace characters we can.
	// . This has the benefit of letting us handle leading whitespace (which is chomped)
	//   and in-line whitespace (which is kept) separately.
	template <> PlainScalarToken *Scanner::ScanToken(PlainScalarToken *pToken)
	{
		// insert a potential simple key
		if(m_simpleKeyAllowed)
			InsertSimpleKey();
		m_simpleKeyAllowed = false;

		// now eat and store the scalar
		std::string scalar;
		WhitespaceInfo info;

		while(INPUT) {
			// doc start/end tokens
			if(IsDocumentStart() || IsDocumentEnd())
				break;

			// comment
			if(Exp::Comment.Matches(INPUT))
				break;

			// first eat non-blanks
			while(INPUT && !Exp::BlankOrBreak.Matches(INPUT)) {
				// illegal colon in flow context
				if(m_flowLevel > 0 && Exp::IllegalColonInScalar.Matches(INPUT))
					throw IllegalScalar();

				// characters that might end the scalar
				if(m_flowLevel > 0 && Exp::EndScalarInFlow.Matches(INPUT))
					break;
				if(m_flowLevel == 0 && Exp::EndScalar.Matches(INPUT))
					break;

				// finally, read the character!
				scalar += GetChar();
			}

			// did we hit a non-blank character that ended us?
			if(!Exp::BlankOrBreak.Matches(INPUT))
				break;

			// now eat blanks
			while(INPUT && Exp::BlankOrBreak.Matches(INPUT)) {
				if(Exp::Blank.Matches(INPUT)) {
					// can't use tabs as indentation! only spaces!
					if(INPUT.peek() == '\t' && info.leadingBlanks && m_column <= m_indents.top())
						throw IllegalTabInScalar();

					info.AddBlank(GetChar());
				} else	{
					// we know it's a line break; see how many characters to read
					int n = Exp::Break.Match(INPUT);
					std::string line = GetChar(n);
					info.AddBreak(line);

					// and we can't continue a simple key to the next line
					ValidateSimpleKey();
				}
			}

			// break if we're below the indentation level
			if(m_flowLevel == 0 && m_column <= m_indents.top())
				break;

			// finally join whitespace
			scalar += info.Join();
		}

		// now modify our token
		pToken->value = scalar;
		if(info.leadingBlanks)
			m_simpleKeyAllowed = true;

		return pToken;
	}

	// QuotedScalarToken
	template <> QuotedScalarToken *Scanner::ScanToken(QuotedScalarToken *pToken)
	{
		// insert a potential simple key
		if(m_simpleKeyAllowed)
			InsertSimpleKey();
		m_simpleKeyAllowed = false;

		// eat single or double quote
		char quote = GetChar();
		bool single = (quote == '\'');

		// now eat and store the scalar
		std::string scalar;
		WhitespaceInfo info;

		while(INPUT) {
			if(IsDocumentStart() || IsDocumentEnd())
				throw DocIndicatorInQuote();

			if(INPUT.peek() == EOF)
				throw EOFInQuote();

			// first eat non-blanks
			while(INPUT && !Exp::BlankOrBreak.Matches(INPUT)) {
				// escaped single quote?
				if(single && Exp::EscSingleQuote.Matches(INPUT)) {
					int n = Exp::EscSingleQuote.Match(INPUT);
					scalar += GetChar(n);
					continue;
				}

				// is the quote ending?
				if(INPUT.peek() == (single ? '\'' : '\"'))
					break;

				// escaped newline?
				if(Exp::EscBreak.Matches(INPUT))
					break;

				// other escape sequence
				if(INPUT.peek() == '\\') {
					int length = 0;
					scalar += Exp::Escape(INPUT, length);
					m_column += length;
					continue;
				}

				// and finally, just add the damn character
				scalar += GetChar();
			}

			// is the quote ending?
			if(INPUT.peek() == (single ? '\'' : '\"')) {
				// eat and go
				GetChar();
				break;
			}

			// now we eat blanks
			while(Exp::BlankOrBreak.Matches(INPUT)) {
				if(Exp::Blank.Matches(INPUT)) {
					info.AddBlank(GetChar());
				} else {
					// we know it's a line break; see how many characters to read
					int n = Exp::Break.Match(INPUT);
					std::string line = GetChar(n);
					info.AddBreak(line);

					// and we can't continue a simple key to the next line
					ValidateSimpleKey();
				}
			}

			// and finally join the whitespace
			scalar += info.Join();
		}

		pToken->value = scalar;
		return pToken;
	}

	// BlockScalarToken
	template <> BlockScalarToken *Scanner::ScanToken(BlockScalarToken *pToken)
	{
		// simple keys always ok after block scalars (since we're gonna start a new line anyways)
		m_simpleKeyAllowed = true;

		WhitespaceInfo info;

		// eat block indicator ('|' or '>')
		char indicator = GetChar();
		info.fold = (indicator == Keys::FoldedScalar);

		// eat chomping/indentation indicators
		int n = Exp::Chomp.Match(INPUT);
		for(int i=0;i<n;i++)
			info.SetChompers(GetChar());

		// first eat whitespace
		while(Exp::Blank.Matches(INPUT))
			Eat(1);

		// and comments to the end of the line
		if(Exp::Comment.Matches(INPUT))
			while(INPUT && !Exp::Break.Matches(INPUT))
				Eat(1);

		// if it's not a line break, then we ran into a bad character inline
		if(INPUT && !Exp::Break.Matches(INPUT))
			throw UnexpectedCharacterInBlockScalar();

		// and eat that baby
		EatLineBreak();

		// set the initial indentation
		int indent = info.increment;
		if(info.increment && m_indents.top() >= 0)
			indent += m_indents.top();

		// finally, grab that scalar
		std::string scalar;
		while(INPUT) {
			// initialize indentation
			GetBlockIndentation(indent, info.trailingBreaks);

			// are we done with this guy (i.e. at a lower indentation?)
			if(m_column != indent)
				break;

			bool trailingBlank = Exp::Blank.Matches(INPUT);
			scalar += info.Join();

			bool leadingBlank = Exp::Blank.Matches(INPUT);

			// now eat and save the line
			while(INPUT.peek() != EOF && !Exp::Break.Matches(INPUT))
				scalar += GetChar();

			// we know it's a line break; see how many characters to read
			int n = Exp::Break.Match(INPUT);
			std::string line = GetChar(n);
			info.AddBreak(line);
		}

		// one last whitespace join (with chompers this time)
		scalar += info.Join(true);

		// finally set the scalar
		pToken->value = scalar;

		return pToken;
	}

	// GetBlockIndentation
	// . Helper to scanning a block scalar.
	// . Eats leading *indentation* zeros (i.e., those that come before 'indent'),
	//   and updates 'indent' (if it hasn't been set yet).
	void Scanner::GetBlockIndentation(int& indent, std::string& breaks)
	{
		int maxIndent = 0;

		while(1) {
			// eat as many indentation spaces as we can
			while((indent == 0 || m_column < indent) && INPUT.peek() == ' ')
				Eat(1);

			if(m_column > maxIndent)
				maxIndent = m_column;

			// do we need more indentation, but we've got a tab?
			if((indent == 0 || m_column < indent) && INPUT.peek() == '\t')
				throw IllegalTabInScalar();   // TODO: are literal scalar lines allowed to have tabs here?

			// is this a non-empty line?
			if(!Exp::Break.Matches(INPUT))
				break;

			// otherwise, eat the line break and move on
			int n = Exp::Break.Match(INPUT);
			breaks += GetChar(n);
		}

		// finally, set the indentation
		if(indent == 0) {
			indent = maxIndent;
			if(indent < m_indents.top() + 1)
				indent = m_indents.top() + 1;
			if(indent < 1)
				indent = 1;
		}
	}

	//////////////////////////////////////////////////////////
	// WhitespaceInfo stuff

	Scanner::WhitespaceInfo::WhitespaceInfo(): leadingBlanks(false), fold(true), chomp(0), increment(0)
	{
	}

	void Scanner::WhitespaceInfo::SetChompers(char ch)
	{
		if(ch == '+')
			chomp = 1;
		else if(ch == '-')
			chomp = -1;
		else if(Exp::Digit.Matches(ch)) {
			increment = ch - '0';
			if(increment == 0)
				throw ZeroIndentationInBlockScalar();
		}
	}

	void Scanner::WhitespaceInfo::AddBlank(char ch)
	{
		if(!leadingBlanks)
			whitespace += ch;
	}

	void Scanner::WhitespaceInfo::AddBreak(const std::string& line)
	{
		// where to store this character?
		if(!leadingBlanks) {
			leadingBlanks = true;
			whitespace = "";
			leadingBreaks += line;
		} else
			trailingBreaks += line;
	}

	std::string Scanner::WhitespaceInfo::Join(bool lastLine)
	{
		std::string ret;

		if(leadingBlanks) {
			// fold line break?
			if(fold && Exp::Break.Matches(leadingBreaks) && trailingBreaks.empty() && !lastLine)
				ret = " ";
			else if(!lastLine || chomp != -1)
				ret = leadingBreaks;

			if(!lastLine || chomp == 1)
				ret += trailingBreaks;

			leadingBlanks = false;
			leadingBreaks = "";
			trailingBreaks = "";
		} else if(!whitespace.empty()) {
			ret = whitespace;
			whitespace = "";
		}

		return ret;
	}
}