Merge pull request #248 from earncef/Nil-Coalescing

Nil coalescing operator
mattn · Jun 5, 2018 · 3a1acce · 3a1acce
2 parents eda3e4e + 55307a8
commit 3a1acce
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Showing 8 changed files with 941 additions and 788 deletions.
diff --git a/ast/expr.go b/ast/expr.go
@@ -88,6 +88,13 @@ type BinOpExpr struct {
 	Rhs      Expr
 }
 
+// NilCoalescingOpExpr provide if invalid operator expression.
+type NilCoalescingOpExpr struct {
+	ExprImpl
+	Lhs Expr
+	Rhs Expr
+}
+
 // TernaryOpExpr provide ternary operator expression.
 type TernaryOpExpr struct {
 	ExprImpl

diff --git a/parser/lexer.go b/parser/lexer.go
@@ -145,6 +145,17 @@ retry:
 				tok = int(ch)
 				lit = string(ch)
 			}
+		case '?':
+			s.next()
+			switch s.peek() {
+			case '?':
+				tok = NILCOALESCE
+				lit = "??"
+			default:
+				s.back()
+				tok = int(ch)
+				lit = string(ch)
+			}
 		case '+':
 			s.next()
 			switch s.peek() {
@@ -291,7 +302,7 @@ retry:
 				tok = int(ch)
 				lit = string(ch)
 			}
-		case '\n', '(', ')', ':', ';', '%', '?', '{', '}', '[', ']', ',', '^':
+		case '\n', '(', ')', ':', ';', '%', '{', '}', '[', ']', ',', '^':
 			tok = int(ch)
 			lit = string(ch)
 		default: