Adding colourizing utilities for making pretty output text.

metaprogramming/BUILD

@@ -179,6 +179,23 @@ cc_test(
     ],
 )
 
+################################################################################
+# color.
+################################################################################
+cc_library(
+    name = "color",
+    hdrs = ["color.h"],
+)
+
+cc_test(
+    name = "color_test",
+    srcs = ["color_test.cc"],
+    deps = [
+        ":color",
+        "@googletest//:gtest_main",
+    ],
+)
+
 ################################################################################
 # Concatenate.
 ################################################################################

metaprogramming/color.h

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef JNI_BIND_METAPROGRAMMING_COLOUR_H_
+#define JNI_BIND_METAPROGRAMMING_COLOUR_H_
+
+#include <string>
+#include <string_view>
+
+namespace jni::metaprogramming {
+
+struct Color {
+  static constexpr std::string_view kNone{"\033[0m"};
+
+  // --- Text Colors ---
+  static constexpr std::string_view kBlack = "\033[0;30m";
+  static constexpr std::string_view kBlackBold = "\033[1;30m";
+  static constexpr std::string_view kRed = "\033[0;31m";
+  static constexpr std::string_view kRedBold = "\033[1;31m";
+  static constexpr std::string_view kGreen = "\033[0;32m";
+  static constexpr std::string_view kGreenBold = "\033[1;32m";
+  static constexpr std::string_view kYellow = "\033[0;33m";
+  static constexpr std::string_view kYellowBold = "\033[1;33m";
+  static constexpr std::string_view kBlue = "\033[0;34m";
+  static constexpr std::string_view kBlueBold = "\033[1;34m";
+  static constexpr std::string_view kPurple = "\033[0;35m";
+  static constexpr std::string_view kPurpleBold = "\033[1;35m";
+  static constexpr std::string_view kCyan = "\033[0;36m";
+  static constexpr std::string_view kCyanBold = "\033[1;36m";
+  static constexpr std::string_view kWhite = "\033[0;37m";
+  static constexpr std::string_view kWhiteBold = "\033[1;37m";
+
+  // --- Background Colors ---
+  static constexpr std::string_view kBgBlack = "\033[40m";
+  static constexpr std::string_view kBgBlackBold = "\033[100m";
+  static constexpr std::string_view kBgRed = "\033[41m";
+  static constexpr std::string_view kBgRedBold = "\033[101m";
+  static constexpr std::string_view kBgGreen = "\033[42m";
+  static constexpr std::string_view kBgGreenBold = "\033[102m";
+  static constexpr std::string_view kBgYellow = "\033[43m";
+  static constexpr std::string_view kBgYellowBold = "\033[103m";
+  static constexpr std::string_view kBgBlue = "\033[44m";
+  static constexpr std::string_view kBgBlueBold = "\033[104m";
+  static constexpr std::string_view kBgPurple = "\033[45m";
+  static constexpr std::string_view kBgPurpleBold = "\033[105m";
+  static constexpr std::string_view kBgCyan = "\033[46m";
+  static constexpr std::string_view kBgCyanBold = "\033[106m";
+  static constexpr std::string_view kBgWhite = "\033[47m";
+  static constexpr std::string_view kBgWhiteBold = "\033[107m";
+};
+
+// Colorize function for runtime manipulation of text. This is suitable when
+// the string is unknowable until runtime.
+inline std::string Colorize(std::string_view colour, std::string_view str,
+                            bool colourize = true) {
+  return !colourize ? std::string{str}
+                    : std::string{colour} + std::string{str} +
+                          std::string{Color::kNone};
+}
+
+}  // namespace jni::metaprogramming
+
+#endif  // JNI_BIND_METAPROGRAMMING_COLOUR_H_

metaprogramming/color_test.cc

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "color.h"
+
+#include <cstdio>
+#include <string>
+
+#include <gtest/gtest.h>
+
+using ::jni::metaprogramming::Color;
+using ::jni::metaprogramming::Colorize;
+
+namespace {
+
+TEST(ColorTest, HasBlue) {
+  std::string output = Colorize(Color::kBlue, "Blue words").data();
+
+  printf("%s\n", output.c_str());
+
+  EXPECT_TRUE(Colorize(Color::kBlue, "Blue words").find(Color::kBlue) !=
+              std::string::npos);
+}
+
+TEST(ColorTest, HasGreenAndDoesntBleed) {
+  std::string output = Colorize(Color::kRed, "Red words").data();
+  printf("%s, no color.\n", output.c_str());
+
+  EXPECT_TRUE(output.find(Color::kRed) != std::string::npos);
+  EXPECT_TRUE(output.find(Color::kNone) != std::string::npos);
+}
+
+}  // namespace