libbase: support char parameter in StartsWith/EndsWith.

Bug: 117568547
Test: run libbase_test.
Change-Id: I5a6a412733c594f5a116f333b8e091d2d9f60e06

3 files changed, 22 insertions, 0 deletions

diff --git a/base/include/android-base/strings.h b/base/include/android-base/strings.h
index 9c3556084..fc5c1ce36 100644
--- a/base/include/android-base/strings.h
+++ b/base/include/android-base/strings.h
@@ -61,6 +61,7 @@ bool StartsWith(const std::string& s, const char* prefix);
 bool StartsWithIgnoreCase(const std::string& s, const char* prefix);
 bool StartsWith(const std::string& s, const std::string& prefix);
 bool StartsWithIgnoreCase(const std::string& s, const std::string& prefix);
+bool StartsWith(const std::string& s, char prefix);
 
 // Tests whether 's' ends with 'suffix'.
 // TODO: string_view
@@ -68,6 +69,7 @@ bool EndsWith(const std::string& s, const char* suffix);
 bool EndsWithIgnoreCase(const std::string& s, const char* suffix);
 bool EndsWith(const std::string& s, const std::string& suffix);
 bool EndsWithIgnoreCase(const std::string& s, const std::string& suffix);
+bool EndsWith(const std::string& s, char suffix);
 
 // Tests whether 'lhs' equals 'rhs', ignoring case.
 bool EqualsIgnoreCase(const std::string& lhs, const std::string& rhs);
diff --git a/base/strings.cpp b/base/strings.cpp
index a8bb2a986..2d6eef099 100644
--- a/base/strings.cpp
+++ b/base/strings.cpp
@@ -95,6 +95,10 @@ bool StartsWith(const std::string& s, const std::string& prefix) {
   return strncmp(s.c_str(), prefix.c_str(), prefix.size()) == 0;
 }
 
+bool StartsWith(const std::string& s, char prefix) {
+  return *s.c_str() == prefix;  // Use c_str() to guarantee there is at least a '\0'.
+}
+
 bool StartsWithIgnoreCase(const std::string& s, const char* prefix) {
   return strncasecmp(s.c_str(), prefix, strlen(prefix)) == 0;
 }
@@ -121,6 +125,10 @@ bool EndsWith(const std::string& s, const std::string& suffix) {
   return EndsWith(s, suffix.c_str(), suffix.size(), true);
 }
 
+bool EndsWith(const std::string& s, char suffix) {
+  return EndsWith(s, &suffix, 1, true);
+}
+
 bool EndsWithIgnoreCase(const std::string& s, const char* suffix) {
   return EndsWith(s, suffix, strlen(suffix), false);
 }
diff --git a/base/strings_test.cpp b/base/strings_test.cpp
index b8639ead4..9d740947e 100644
--- a/base/strings_test.cpp
+++ b/base/strings_test.cpp
@@ -198,6 +198,12 @@ TEST(strings, StartsWithIgnoreCase_contains_prefix) {
   ASSERT_FALSE(android::base::StartsWithIgnoreCase("foobar", "BAR"));
 }
 
+TEST(strings, StartsWith_char) {
+  ASSERT_FALSE(android::base::StartsWith("", 'f'));
+  ASSERT_TRUE(android::base::StartsWith("foo", 'f'));
+  ASSERT_FALSE(android::base::StartsWith("foo", 'o'));
+}
+
 TEST(strings, EndsWith_empty) {
   ASSERT_FALSE(android::base::EndsWith("", "foo"));
   ASSERT_TRUE(android::base::EndsWith("", ""));
@@ -273,6 +279,12 @@ TEST(strings, EndsWithIgnoreCase_std_string) {
   ASSERT_FALSE(android::base::EndsWithIgnoreCase("GoOdByE", std::string{"lo"}));
 }
 
+TEST(strings, EndsWith_char) {
+  ASSERT_FALSE(android::base::EndsWith("", 'o'));
+  ASSERT_TRUE(android::base::EndsWith("foo", 'o'));
+  ASSERT_FALSE(android::base::EndsWith("foo", "f"));
+}
+
 TEST(strings, EqualsIgnoreCase) {
   ASSERT_TRUE(android::base::EqualsIgnoreCase("foo", "FOO"));
   ASSERT_TRUE(android::base::EqualsIgnoreCase("FOO", "foo"));