From 627c80f0a8b37426c2c6625ff4852d77e4d43464 Mon Sep 17 00:00:00 2001
From: Christian <c@ethdev.com>
Date: Wed, 5 Nov 2014 08:40:21 +0100
Subject: [PATCH] Support for negative literals.

---
 Scanner.cpp | 22 +++++++++++-----------
 Scanner.h   |  2 +-
 Types.cpp   |  8 +++++---
 3 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/Scanner.cpp b/Scanner.cpp
index 63deba495..b13e52d7e 100644
--- a/Scanner.cpp
+++ b/Scanner.cpp
@@ -271,7 +271,7 @@ void Scanner::scanToken()
 				token = Token::ADD;
 			break;
 		case '-':
-			// - -- -=
+			// - -- -= Number
 			advance();
 			if (m_char == '-')
 			{
@@ -280,6 +280,8 @@ void Scanner::scanToken()
 			}
 			else if (m_char == '=')
 				token = selectToken(Token::ASSIGN_SUB);
+			else if (m_char == '.' || IsDecimalDigit(m_char))
+				token = scanNumber('-');
 			else
 				token = Token::SUB;
 			break;
@@ -331,7 +333,7 @@ void Scanner::scanToken()
 			// . Number
 			advance();
 			if (IsDecimalDigit(m_char))
-				token = scanNumber(true);
+				token = scanNumber('.');
 			else
 				token = Token::PERIOD;
 			break;
@@ -372,7 +374,7 @@ void Scanner::scanToken()
 			if (IsIdentifierStart(m_char))
 				token = scanIdentifierOrKeyword();
 			else if (IsDecimalDigit(m_char))
-				token = scanNumber(false);
+				token = scanNumber();
 			else if (skipWhitespace())
 				token = Token::WHITESPACE;
 			else if (isSourcePastEndOfInput())
@@ -461,14 +463,11 @@ void Scanner::scanDecimalDigits()
 }
 
 
-Token::Value Scanner::scanNumber(bool _periodSeen)
+Token::Value Scanner::scanNumber(char _charSeen)
 {
-	// the first digit of the number or the fraction
-	if (asserts(IsDecimalDigit(m_char)))
-		BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Number does not start with decimal digit."));
-	enum { DECIMAL, HEX, OCTAL, IMPLICIT_OCTAL, BINARY } kind = DECIMAL;
+	enum { DECIMAL, HEX, BINARY } kind = DECIMAL;
 	LiteralScope literal(this);
-	if (_periodSeen)
+	if (_charSeen == '.')
 	{
 		// we have already seen a decimal point of the float
 		addLiteralChar('.');
@@ -476,12 +475,13 @@ Token::Value Scanner::scanNumber(bool _periodSeen)
 	}
 	else
 	{
+		if (_charSeen == '-')
+			addLiteralChar('-');
 		// if the first character is '0' we must check for octals and hex
 		if (m_char == '0')
 		{
 			addLiteralCharAndAdvance();
-			// either 0, 0exxx, 0Exxx, 0.xxx, a hex number, a binary number or
-			// an octal number.
+			// either 0, 0exxx, 0Exxx, 0.xxx or a hex number
 			if (m_char == 'x' || m_char == 'X')
 			{
 				// hex number
diff --git a/Scanner.h b/Scanner.h
index 537c2434e..997365f3c 100644
--- a/Scanner.h
+++ b/Scanner.h
@@ -180,7 +180,7 @@ private:
 	Token::Value skipMultiLineComment();
 
 	void scanDecimalDigits();
-	Token::Value scanNumber(bool _periodSeen);
+	Token::Value scanNumber(char _charSeen = 0);
 	Token::Value scanIdentifierOrKeyword();
 
 	Token::Value scanString();
diff --git a/Types.cpp b/Types.cpp
index 334f50444..7354255e1 100644
--- a/Types.cpp
+++ b/Types.cpp
@@ -89,10 +89,14 @@ shared_ptr<Type> Type::forLiteral(Literal const& _literal)
 shared_ptr<IntegerType> IntegerType::smallestTypeForLiteral(string const& _literal)
 {
 	bigint value(_literal);
+	bool isSigned = value < 0 || (!_literal.empty() && _literal.front() == '-');
+	if (isSigned)
+		// convert to positive number of same bit requirements
+		value = ((-value) - 1) << 1;
 	unsigned bytes = max(bytesRequired(value), 1u);
 	if (bytes > 32)
 		return shared_ptr<IntegerType>();
-	return make_shared<IntegerType>(bytes * 8, Modifier::UNSIGNED);
+	return make_shared<IntegerType>(bytes * 8, isSigned ? Modifier::SIGNED : Modifier::UNSIGNED);
 }
 
 IntegerType::IntegerType(int _bits, IntegerType::Modifier _modifier):
@@ -169,8 +173,6 @@ string IntegerType::toString() const
 u256 IntegerType::literalValue(Literal const& _literal) const
 {
 	bigint value(_literal.getValue());
-	//@todo check that the number is not too large
-	//@todo does this work for signed numbers?
 	return u256(value);
 }