utils/include/hidl-util/Formatter.h

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * 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 FORMATTER_H_

#define FORMATTER_H_

#include <android-base/macros.h>
#include <functional>
#include <string>

namespace android {

// Two styles to use a Formatter.
// One is with .indent() calls and operator<<.
//     out << "if (good) {\n"; out.indent(); out << "blah\nblah\n"; out.unindent(); out << "}\n";
// The other is with chain calls and lambda functions
//     out.sIf("good", [&] { out("blah").endl()("blah").endl(); }).endl();
struct Formatter {

    // Assumes ownership of file. Directed to stdout if file == NULL.
    Formatter(FILE *file = NULL);
    ~Formatter();

    void indent(size_t level = 1);
    void unindent(size_t level = 1);

    // Note that The last \n after the last line is NOT added automatically.
    // out.indent(2, [&] {
    //     out << "Meow\n";
    // });
    Formatter &indent(size_t level, std::function<void(void)> func);

    // Note that The last \n after the last line is NOT added automatically.
    // out.indent([&] {
    //     out << "Meow\n";
    // });
    Formatter &indent(std::function<void(void)> func);

    // A block inside braces.
    // * No space will be added before the opening brace.
    // * The last \n before the closing brace is added automatically.
    // * There will NOT be a \n after the closing brace.
    // out.block([&] {
    //     out << "one();\n"
    //         << "two();\n";
    // });
    // is equivalent to
    // out << "{\n"
    //     << "one();\ntwo();\n" // func()
    //     << "}";
    Formatter &block(std::function<void(void)> func);

    // A synonym to (*this) << "\n";
    Formatter &endl();

    // out.sIf("z == 1", [&] {
    //     out << "doGoodStuff();\n";
    // }).sElseIf("z == 2", [&] {
    //     out << "doBadStuff();\n";
    // }).sElse([&] {
    //     out << "logFatal();\n";
    // }).endl();
    // note that there will be a space before the "else"-s.
    Formatter &sIf(const std::string &cond, std::function<void(void)> block);
    Formatter &sElseIf(const std::string &cond, std::function<void(void)> block);
    Formatter &sElse(std::function<void(void)> block);

    // out.sTry([&] {
    //     out << "throw RemoteException();\n"
    // }).sCatch("RemoteException ex", [&] {
    //     out << "ex.printStackTrace();\n"
    // }).endl();
    // note that there will be a space before the "catch"-s.
    Formatter &sTry(std::function<void(void)> block);
    Formatter &sCatch(const std::string &exception, std::function<void(void)> block);

    Formatter &operator<<(const std::string &out);
    Formatter &operator<<(size_t n);

    // Any substrings matching "space" will be stripped out of the output.
    void setNamespace(const std::string &space);

    // Puts a prefix before each line. This is useful if
    // you want to start a // comment block, for example.
    // The prefix will be put before the indentation.
    // Will be effective the next time cursor is at the start of line.
    void setLinePrefix(const std::string& prefix);
    // Remove the line prefix.
    void unsetLinePrefix();

private:
    FILE *mFile;
    size_t mIndentDepth;
    bool mAtStartOfLine;

    std::string mSpace;
    std::string mLinePrefix;

    void output(const std::string &text) const;

    DISALLOW_COPY_AND_ASSIGN(Formatter);
};

}  // namespace android

#endif  // FORMATTER_H_