Add interface for C++17 string_view (2.rc.02)

Makefile

@@ -0,0 +1,48 @@
+WARNINGS=                    \
+   -Werror                   \
+   -Wall                     \
+   -Wextra                   \
+   -pedantic                 \
+   -Wcast-align              \
+   -Wcast-qual               \
+   -Wctor-dtor-privacy       \
+   -Wdisabled-optimization   \
+   -Wformat=2                \
+   -Winit-self               \
+   -Wlogical-op              \
+   -Wmissing-include-dirs    \
+   -Wnoexcept                \
+   -Wold-style-cast          \
+   -Woverloaded-virtual      \
+   -Wredundant-decls         \
+   -Wshadow                  \
+   -Wsign-promo              \
+   -Wstrict-null-sentinel    \
+   -Wstrict-overflow=5       \
+   -Wundef                   \
+   -Wno-unused               \
+   -Wno-variadic-macros      \
+   -Wno-parentheses          \
+   -fdiagnostics-show-option
+
+test: base64-test-11 base64-test-17
+	base64-test-11
+	base64-test-17
+
+base64-test-11: base64-11.o test-11.o
+	g++ base64-11.o test-11.o -o $@
+
+base64-test-17: base64-17.o test-17.o
+	g++ base64-17.o test-17.o -o $@
+
+base64-11.o: base64.cpp base64.h
+	g++ -std=c++11 $(WARNINGS) -c base64.cpp -o base64-11.o
+
+base64-17.o: base64.cpp base64.h
+	g++ -std=c++17 $(WARNINGS) -c base64.cpp -o base64-17.o
+
+test-11.o: test.cpp
+	g++ -std=c++11 $(WARNINGS) -c test.cpp -o test-11.o
+
+test-17.o: test.cpp
+	g++ -std=c++17 $(WARNINGS) -c test.cpp -o test-17.o

base64.cpp

@@ -5,7 +5,7 @@
    More information at
      https://renenyffenegger.ch/notes/development/Base64/Encoding-and-decoding-base-64-with-cpp
 
-   Version: 2.rc.01 (release candidate)
+   Version: 2.rc.02 (release candidate)
 
    Copyright (C) 2004-2017, 2020 René Nyffenegger
 
@@ -72,6 +72,26 @@ static std::string insert_linebreaks(std::string str, size_t distance) {
     return str;
 }
 
+template <typename String, unsigned int line_length>
+static std::string encode_with_line_breaks(String s) {
+  return insert_linebreaks(base64_encode(s, false), line_length);
+}
+
+template <typename String>
+static std::string encode_pem(String s) {
+  return encode_with_line_breaks<String, 64>(s);
+}
+
+template <typename String>
+static std::string encode_mime(String s) {
+  return encode_with_line_breaks<String, 76>(s);
+}
+
+template <typename String>
+static std::string encode(String s, bool url) {
+  return base64_encode(reinterpret_cast<const unsigned char*>(s.data()), s.length(), url);
+}
+
 std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len, bool url) {
  //
  // Replace question marks in base64_chars:
@@ -123,8 +143,12 @@ std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_
     return ret;
 }
 
-
-std::string base64_decode(std::string const& encoded_string, bool remove_linebreaks) {
+template <typename String>
+static std::string decode(String encoded_string, bool remove_linebreaks) {
+ //
+ // decode(…) is templated so that it can be used with String = const std::string&
+ // or std::string_view (requires at least C++17)
+ //
 
     if (remove_linebreaks) {
 
@@ -181,14 +205,43 @@ std::string base64_decode(std::string const& encoded_string, bool remove_linebre
     return ret;
 }
 
+std::string base64_decode(std::string const& s, bool remove_linebreaks) {
+  return decode(s, remove_linebreaks);
+}
+
 std::string base64_encode(std::string const& s, bool url) {
-   return base64_encode(reinterpret_cast<const unsigned char*>(s.c_str()), s.length(), url);
+   return encode(s, url);
 }
 
 std::string base64_encode_pem (std::string const& s) {
-   return insert_linebreaks(base64_encode(s, false), 64);
+   return encode_pem(s);
 }
 
 std::string base64_encode_mime(std::string const& s) {
-   return insert_linebreaks(base64_encode(s, false), 76);
+   return encode_mime(s);
+}
+
+#if __cplusplus >= 201703L
+//
+// Interface with std::string_view rather than const std::string&
+// Requires C++17
+// Provided by Yannic Bonenberger (https://github.com/Yannic)
+//
+
+std::string base64_encode(std::string_view s, bool url) {
+   return encode(s, url);
+}
+
+std::string base64_encode_pem(std::string_view s) {
+   return encode_pem(s);
 }
+
+std::string base64_encode_mime(std::string_view s) {
+   return encode_mime(s);
+}
+
+std::string base64_decode(std::string_view s, bool remove_linebreaks) {
+  return decode(s, remove_linebreaks);
+}
+
+#endif  // __cplusplus >= 201703L

base64.h

@@ -1,18 +1,35 @@
 //
 //  base64 encoding and decoding with C++.
-//  Version: 2.rc.01 (release candidate)
+//  Version: 2.rc.02 (release candidate)
 //
 
 #ifndef BASE64_H_C0CE2A47_D10E_42C9_A27C_C883944E704A
 #define BASE64_H_C0CE2A47_D10E_42C9_A27C_C883944E704A
 
 #include <string>
 
+#if __cplusplus >= 201703L
+#include <string_view>
+#endif  // __cplusplus >= 201703L
+
 std::string base64_encode     (std::string const& s, bool url = false);
 std::string base64_encode_pem (std::string const& s);
 std::string base64_encode_mime(std::string const& s);
 
 std::string base64_decode(std::string const& s, bool remove_linebreaks = false);
 std::string base64_encode(unsigned char const*, unsigned int len, bool url = false);
 
+#if __cplusplus >= 201703L
+//
+// Interface with std::string_view rather than const std::string&
+// Requires C++17
+// Provided by Yannic Bonenberger (https://github.com/Yannic)
+//
+std::string base64_encode     (std::string_view s, bool url = false);
+std::string base64_encode_pem (std::string_view s);
+std::string base64_encode_mime(std::string_view s);
+
+std::string base64_decode(std::string_view s, bool remove_linebreaks = false);
+#endif  // __cplusplus >= 201703L
+
 #endif /* BASE64_H_C0CE2A47_D10E_42C9_A27C_C883944E704A */

test.cpp

@@ -5,7 +5,7 @@ int main() {
 
   bool all_tests_passed = true;
 
-  const std::string orig = 
+  const std::string orig =
     "René Nyffenegger\n"
     "http://www.renenyffenegger.ch\n"
     "passion for data\n";
@@ -102,6 +102,30 @@ int main() {
         all_tests_passed = false;
     }
 
+
+ // --------------------------------------------------------------
+
+#if __cplusplus >= 201703L
+ //
+ // Test the string_view interface (which required C++17)
+ //
+    std::string_view sv_orig    = "foobarbaz";
+    std::string_view sv_encoded = base64_encode(sv_orig);
+
+    if (sv_encoded != "Zm9vYmFyYmF6") {
+       std::cout << "Failed to encode with string_view" << std::endl;
+       all_tests_passed = false;
+    }
+
+    std::string_view sv_decoded = base64_decode(sv_encoded);
+
+    if (sv_decoded != sv_orig) {
+       std::cout << "Failed to decode with string_view" << std::endl;
+       all_tests_passed = false;
+    }
+
+#endif
+
     if (all_tests_passed) return 0;
     return 1;
 }