From e5ba9aaa6e4d2b45c5aa492b7a31e4bd94fbcc4c Mon Sep 17 00:00:00 2001
From: Shunsuke Michii <harukasan@me.com>
Date: Tue, 4 Oct 2016 02:43:03 +0900
Subject: [PATCH 1/2] Add parsing begin of symbol.

---
 scanner/scanner.go      | 13 ++++++++++++-
 scanner/scanner_test.go | 38 ++++++++++++++++++++++++++++++++++++++
 token/token.go          |  1 +
 3 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/scanner/scanner.go b/scanner/scanner.go
index 86cd3cb..2e09968 100644
--- a/scanner/scanner.go
+++ b/scanner/scanner.go
@@ -405,10 +405,21 @@ func scanDiv(s *Scanner) (token.Token, []byte) {
 	return token.Div, nil
 }
 
+func isSymbolPrefix(c byte) bool {
+	return (('!' <= c && c != '#' && c <= '\'') ||
+		('*' <= c && c != ',' && c != '.' && c <= '9') ||
+		('<' <= c && c != '?' && c <= '[') ||
+		('^' <= c && c <= 'z') ||
+		c == '~')
+}
+
 func scanColon(s *Scanner) (token.Token, []byte) {
-	if s.char == ':' {
+	switch {
+	case s.char == ':':
 		s.next()
 		return token.Colon2, nil
+	case isSymbolPrefix(s.char):
+		return token.SymbolBegin, nil
 	}
 	return token.Colon, nil
 }
diff --git a/scanner/scanner_test.go b/scanner/scanner_test.go
index 95137e6..ad3334a 100644
--- a/scanner/scanner_test.go
+++ b/scanner/scanner_test.go
@@ -324,6 +324,44 @@ var rules = map[string][]struct {
 		{3, token.IdentLocalVar, []byte("b")},
 	},
 
+	// symbol
+	":a": {
+		{0, token.SymbolBegin, nil},
+		{1, token.IdentLocalVar, []byte("a")},
+	},
+	":@a": {
+		{0, token.SymbolBegin, nil},
+		{1, token.IdentInstanceVar, []byte("@a")},
+	},
+	":@@a": {
+		{0, token.SymbolBegin, nil},
+		{1, token.IdentClassVar, []byte("@@a")},
+	},
+	":$a": {
+		{0, token.SymbolBegin, nil},
+		{1, token.IdentGlobalVar, []byte("$a")},
+	},
+	":<<": {
+		{0, token.SymbolBegin, nil},
+		{1, token.LShift, nil},
+	},
+	":'a'": {
+		{0, token.SymbolBegin, nil},
+		{1, token.String, []byte("a")},
+	},
+	":\"a\"": {
+		{0, token.SymbolBegin, nil},
+		{1, token.String, []byte("a")},
+	},
+	":\"#{a}\"": {
+		{0, token.SymbolBegin, nil},
+		{1, token.StringPart, nil},
+		{2, token.InsertBegin, nil},
+		{4, token.IdentLocalVar, []byte("a")},
+		{5, token.InsertEnd, nil},
+		{6, token.String, nil},
+	},
+
 	// keywords
 	"__LINE__":     {{0, token.KeywordLINE, nil}},
 	"__ENCODING__": {{0, token.KeywordENCODING, nil}},
diff --git a/token/token.go b/token/token.go
index 966c24e..fb900da 100644
--- a/token/token.go
+++ b/token/token.go
@@ -27,6 +27,7 @@ const (
 	HeredocEnd
 	InsertBegin
 	InsertEnd
+	SymbolBegin
 
 	// brackets:
 	LParen   // (

From b57d6499ef42453cf24ffa89796a9b9ad676c9fa Mon Sep 17 00:00:00 2001
From: Shunsuke Michii <harukasan@me.com>
Date: Tue, 4 Oct 2016 02:57:48 +0900
Subject: [PATCH 2/2] Make isSymbolPrefix to lookup table.

---
 scanner/scanner.go | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/scanner/scanner.go b/scanner/scanner.go
index 2e09968..a342645 100644
--- a/scanner/scanner.go
+++ b/scanner/scanner.go
@@ -405,12 +405,31 @@ func scanDiv(s *Scanner) (token.Token, []byte) {
 	return token.Div, nil
 }
 
+var symbolPrefixMap = [...]bool{
+	'!':  true,
+	'"':  true,
+	'$':  true,
+	'%':  true,
+	'&':  true,
+	'\'': true,
+	'*':  true,
+	'+':  true,
+	'-':  true,
+	'/':  true,
+	'<':  true,
+	'=':  true,
+	'>':  true,
+	'@':  true,
+	'[':  true,
+	'^':  true,
+	'_':  true,
+	'`':  true,
+	'|':  true,
+	'~':  true,
+}
+
 func isSymbolPrefix(c byte) bool {
-	return (('!' <= c && c != '#' && c <= '\'') ||
-		('*' <= c && c != ',' && c != '.' && c <= '9') ||
-		('<' <= c && c != '?' && c <= '[') ||
-		('^' <= c && c <= 'z') ||
-		c == '~')
+	return token.IsAlnum(c) || symbolPrefixMap[c]
 }
 
 func scanColon(s *Scanner) (token.Token, []byte) {