From 22457f8cd8805903720d7c8b4cfec8e9dcb6758d Mon Sep 17 00:00:00 2001
From: Jeffrey Wilcke <jeffrey@ethereum.org>
Date: Mon, 20 Feb 2017 08:59:14 +0100
Subject: [PATCH] cmd/easm: added comments ;;

---
 cmd/easm/lex_test.go | 20 ++++++++++++++++++++
 cmd/easm/lexer.go    | 11 +++++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 cmd/easm/lex_test.go

diff --git a/cmd/easm/lex_test.go b/cmd/easm/lex_test.go
new file mode 100644
index 0000000000..a1b513c49e
--- /dev/null
+++ b/cmd/easm/lex_test.go
@@ -0,0 +1,20 @@
+package main
+
+import "testing"
+
+func lexAll(src string) []item {
+	ch := lex("test.asm", []byte(src), false)
+
+	var tokens []item
+	for i := range ch {
+		tokens = append(tokens, i)
+	}
+	return tokens
+}
+
+func TestComment(t *testing.T) {
+	tokens := lexAll(";; this is a comment")
+	if len(tokens) != 2 { // {new line, EOF}
+		t.Error("expected no tokens")
+	}
+}
diff --git a/cmd/easm/lexer.go b/cmd/easm/lexer.go
index d7320f399d..eb46f52d46 100644
--- a/cmd/easm/lexer.go
+++ b/cmd/easm/lexer.go
@@ -186,6 +186,8 @@ func lexLine(l *Lexer) stateFn {
 			l.lineno++
 
 			l.emit(lineStart)
+		case r == ';' && l.peek() == ';':
+			return lexComment
 		case isSpace(r):
 			l.ignore()
 		case isAlphaNumeric(r) || r == '_':
@@ -203,6 +205,15 @@ func lexLine(l *Lexer) stateFn {
 	}
 }
 
+// lexComment parses the current position until the end
+// of the line and discards the text.
+func lexComment(l *Lexer) stateFn {
+	l.acceptRunUntil('\n')
+	l.ignore()
+
+	return lexLine
+}
+
 // lexLabel parses the current label, emits and returns
 // the lex text state function to advance the parsing
 // process.