syntax: allow newline after expression

Change-Id: I3087d84e4be9f85a68ec088ea5935a7d18fd0407

syntax/parse.go

@@ -52,6 +52,12 @@ func ParseExpr(filename string, src interface{}) (expr Expr, err error) {
 	p.nextToken() // read first lookahead token
 	expr = p.parseTest()
 
+	// A following newline (e.g. "f()\n") appears outside any brackets,
+	// on a non-blank line, and is thus materialized.
+	if p.tok == NEWLINE {
+		p.nextToken()
+	}
+
 	if p.tok != EOF {
 		p.in.errorf(p.in.pos, "got %#v after expression, want EOF", p.tok)
 	}

syntax/parse_test.go

@@ -22,6 +22,8 @@ func TestExprParseTrees(t *testing.T) {
 	}{
 		{`print(1)`,
 			`(CallExpr Fn=print Args=(1))`},
+		{"print(1)\n",
+			`(CallExpr Fn=print Args=(1))`},
 		{`x + 1`,
 			`(BinaryExpr X=x Op=+ Y=1)`},
 		{`[x for x in y]`,

syntax/scan_test.go

@@ -61,6 +61,7 @@ func TestScanner(t *testing.T) {
 		{`123 "foo" hello x.y`, `123 "foo" hello x . y EOF`},
 		{`print(x)`, "print ( x ) EOF"},
 		{`print(x); print(y)`, "print ( x ) ; print ( y ) EOF"},
+		{"\nprint(\n1\n)\n", "print ( 1 ) newline EOF"}, // final \n is at toplevel on non-blank line => token
 		{`/ // /= //= ///=`, "/ // /= //= // /= EOF"},
 		{`# hello
 print(x)`, "print ( x ) EOF"},