Correctly handle empty vector when printing

before this CL, an empty vector passed to 'dumpVector' would cause a
crash (in the good case) and undefined behaviour otherwise.

In this CL, fix this function.

Bug: 211379801
Test: TEST=inputflinger_tests; m $TEST && $ANDROID_HOST_OUT/nativetest64/$TEST/$TEST
Change-Id: I93f4defb947f41d68f0ec22bd35b6c069fbc15e4

1 files changed, 5 insertions, 4 deletions

diff --git a/include/input/PrintTools.h b/include/input/PrintTools.h
index 83fffa37c6..3470be4dce 100644
--- a/include/input/PrintTools.h
+++ b/include/input/PrintTools.h
@@ -117,11 +117,12 @@ std::string dumpMapKeys(const std::map<K, V>& map,
 template <typename T>
 std::string dumpVector(const std::vector<T>& values,
                        std::string (*valueToString)(const T&) = constToString) {
-    std::string dump = valueToString(values[0]);
-    for (size_t i = 1; i < values.size(); i++) {
-        dump += ", " + valueToString(values[i]);
+    std::string out;
+    for (const auto& value : values) {
+        out += out.empty() ? "[" : ", ";
+        out += valueToString(value);
     }
-    return dump;
+    return out.empty() ? "[]" : (out + "]");
 }
 
 const char* toString(bool value);