From 00e06fb432f357467be5f87ae8db233aab11b741 Mon Sep 17 00:00:00 2001
From: Fatih Arslan <ftharsln@gmail.com>
Date: Mon, 5 Oct 2015 12:59:55 +0300
Subject: [PATCH] scanner: finalize float scanning

---
 scanner/scanner.go      | 49 +++++++++++++++++++++++------------------
 scanner/scanner_test.go | 38 ++++++++++++++++----------------
 2 files changed, 46 insertions(+), 41 deletions(-)

diff --git a/scanner/scanner.go b/scanner/scanner.go
index 63480ab..8fe0651 100644
--- a/scanner/scanner.go
+++ b/scanner/scanner.go
@@ -162,15 +162,17 @@ func (s *Scanner) scanNumber(ch rune) token.Token {
 			ch = s.next()
 			if ch == '8' || ch == '9' {
 				// this is just a possibility. For example 0159 is illegal, but
-				// 159.23 is valid. So we mark a possible illegal octal. If the
-				// next character is not a period, we'll print the error
+				// 0159.23 is valid. So we mark a possible illegal octal. If
+				// the next character is not a period, we'll print the error.
 				illegalOctal = true
 
 			}
+
 		}
 		s.unread()
 
 		if ch == '.' || ch == 'e' || ch == 'E' {
+			ch = s.next()
 			ch = s.scanFraction(ch)
 			ch = s.scanExponent(ch)
 			return token.FLOAT
@@ -184,8 +186,8 @@ func (s *Scanner) scanNumber(ch rune) token.Token {
 	}
 
 	ch = s.scanMantissa(ch)
-	fmt.Printf("ch = %q\n", ch)
 	if ch == '.' || ch == 'e' || ch == 'E' {
+		ch = s.next() // seek forward
 		ch = s.scanFraction(ch)
 		ch = s.scanExponent(ch)
 		return token.FLOAT
@@ -193,25 +195,6 @@ func (s *Scanner) scanNumber(ch rune) token.Token {
 	return token.NUMBER
 }
 
-func (s *Scanner) scanFraction(ch rune) rune {
-	if ch == '.' {
-		ch = s.next()
-		ch = s.scanMantissa(ch)
-	}
-	return ch
-}
-
-func (s *Scanner) scanExponent(ch rune) rune {
-	if ch == 'e' || ch == 'E' {
-		ch = s.next()
-		if ch == '-' || ch == '+' {
-			ch = s.next()
-		}
-		ch = s.scanMantissa(ch)
-	}
-	return ch
-}
-
 // scanMantissa scans the mantissa begining from the rune. It returns the next
 // non decimal rune. It's used to determine wheter it's a fraction or exponent.
 func (s *Scanner) scanMantissa(ch rune) rune {
@@ -227,6 +210,28 @@ func (s *Scanner) scanMantissa(ch rune) rune {
 	return ch
 }
 
+func (s *Scanner) scanFraction(ch rune) rune {
+	if ch == '.' {
+		ch = s.next()
+		msCh := s.scanMantissa(ch)
+		if msCh == ch {
+			s.unread()
+		}
+	}
+	return ch
+}
+
+func (s *Scanner) scanExponent(ch rune) rune {
+	if ch == 'e' || ch == 'E' {
+		ch = s.next()
+		if ch == '-' || ch == '+' {
+			ch = s.next()
+		}
+		ch = s.scanMantissa(ch)
+	}
+	return ch
+}
+
 // scanString scans a quoted string
 func (s *Scanner) scanString() {
 	for {
diff --git a/scanner/scanner_test.go b/scanner/scanner_test.go
index e4d75fb..4c7992f 100644
--- a/scanner/scanner_test.go
+++ b/scanner/scanner_test.go
@@ -132,25 +132,25 @@ func TestNumber(t *testing.T) {
 		{token.FLOAT, ".42"},
 		{token.FLOAT, ".0123456789"},
 		{token.FLOAT, "0.0"},
-		// {token.FLOAT, "1.0"},
-		// {token.FLOAT, "42.0"},
-		// {token.FLOAT, "01234567890.0"},
-		// {token.FLOAT, "0e0"},
-		// {token.FLOAT, "1e0"},
-		// {token.FLOAT, "42e0"},
-		// {token.FLOAT, "01234567890e0"},
-		// {token.FLOAT, "0E0"},
-		// {token.FLOAT, "1E0"},
-		// {token.FLOAT, "42E0"},
-		// {token.FLOAT, "01234567890E0"},
-		// {token.FLOAT, "0e+10"},
-		// {token.FLOAT, "1e-10"},
-		// {token.FLOAT, "42e+10"},
-		// {token.FLOAT, "01234567890e-10"},
-		// {token.FLOAT, "0E+10"},
-		// {token.FLOAT, "1E-10"},
-		// {token.FLOAT, "42E+10"},
-		// {token.FLOAT, "01234567890E-10"},
+		{token.FLOAT, "1.0"},
+		{token.FLOAT, "42.0"},
+		{token.FLOAT, "01234567890.0"},
+		{token.FLOAT, "0e0"},
+		{token.FLOAT, "1e0"},
+		{token.FLOAT, "42e0"},
+		{token.FLOAT, "01234567890e0"},
+		{token.FLOAT, "0E0"},
+		{token.FLOAT, "1E0"},
+		{token.FLOAT, "42E0"},
+		{token.FLOAT, "01234567890E0"},
+		{token.FLOAT, "0e+10"},
+		{token.FLOAT, "1e-10"},
+		{token.FLOAT, "42e+10"},
+		{token.FLOAT, "01234567890e-10"},
+		{token.FLOAT, "0E+10"},
+		{token.FLOAT, "1E-10"},
+		{token.FLOAT, "42E+10"},
+		{token.FLOAT, "01234567890E-10"},
 	}
 
 	testTokenList(t, tokenList)