parser: Don't panic on single eof token

When the expressin is empty the lexer will return a slice of tokens with just one EOF, there is a bug at parser that throws a panic trying to access the last token. This change add the guard to prevent that. Signed-off-by: Quique Llorente <[email protected]>
nmstate · Dec 2, 2021 · f4ed96a · f4ed96a
1 parent b863b90
commit f4ed96a
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diff --git a/nmpolicy/internal/parser/parser.go b/nmpolicy/internal/parser/parser.go
@@ -76,6 +76,9 @@ func (p *parser) parse() (ast.Node, error) {
 		}
 		p.nextToken()
 	}
+	if p.lastNode == nil {
+		return ast.Node{}, nil
+	}
 	return *p.lastNode, nil
 }
 

diff --git a/nmpolicy/internal/parser/parser_test.go b/nmpolicy/internal/parser/parser_test.go
@@ -99,6 +99,7 @@ func testParseFailures(t *testing.T) {
 func testParseSuccess(t *testing.T) {
 	var tests = []test{
 		expectEmptyAST(fromTokens()),
+		expectEmptyAST(fromTokens(eof())),
 		expectAST(t, `
 pos: 0
 path: