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This is Scanner++ Library

The idea of this project is to have (Java) Scanner functionalities on C++. This is an experimental library in Header Only format (just add Scanner.hpp to your project and that's it!).

Build with Conan + Bazel

This project tries to use both Conan and Bazel (during tests and benchmarks, not production). By Conan, the files at conandeps are created in a compatible manner with Bazel.

Working Example for Conan+Bazel+Benchmark

make test-bazel-bench

This will create conandeps/ folder and initialize bazel dependencies from setup-conandeps-bazel/.

Dependencies

conan search benchmark -r conancenter

conan search tl-expected -r conancenter

Conan + Bazel

pip install conan

Google benchmark requires D_GLIBCXX_USE_CXX11_ABI see issue:

conan install . -s compiler.libcxx=libstdc++11

or install in local conan_cache folder:

mkdir -p conan_cache && export CONAN_USER_HOME=${PWD}/conan_cache && conan install . -s compiler.libcxx=libstdc++11

MAYBE: conan profile update settings.compiler.libcxx=libstdc++11 default TODO: TRY THIS LATER TO MAYBE AVOID PREVIOUS COMMAND...

At conandeps/benchmark/BUILD, small fix, add these into cc_library:

    deps = [":benchmark_precompiled"],
    linkopts = ["-lpthread"],

This prevents link issue with -lbenchmark (libbenchmark.a).

cd tests
./run_bench.sh

If this doesn't work, make bench2 could be manually executed, such as:

g++-9 -g -D_GLIBCXX_USE_CXX11_ABI=0 --std=c++17 -DNDEBUG bench.cpp -I/home/imcoelho/.conan/data/tl-expected/20190710/_/_/package/5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9/include -I/home/imcoelho/.conan/data/benchmark/1.5.3/_/_/package/9ec7e6c55ee108e231bdef75e23776b8b86d821d/include -L/home/imcoelho/.conan/data/benchmark/1.5.3/_/_/package/9ec7e6c55ee108e231bdef75e23776b8b86d821d/lib -lbenchmark -pthread

Listing dependencies

bazel query 'labels(hdrs, @tl-expected//...)'
bazel query 'labels(hdrs, @benchmark//...)'
bazel query 'labels(hdrs, ...)'

Current and Legacy versions

Current version is 1.0, located on ./src folder, and licensed MIT.

Note that previous version 0.98-alpha, located on ./legacy, was licensed LGPLv3 (project previously ported from SourceForge: https://sourceforge.net/projects/scannerpp/).

There are many reasons for the change:

  • A complete code rewrite was necessary, as 0.98-alpha version did not consider important c++11 features, such as move semantics, nor any other recent c++ advances (c++14, c++17 and c++20)
  • The organization as a single header file (.hpp) is much more desirable than separated .h and .cpp, as a link library format. This facilitates integration with projects.
  • Unit testing was heavily desired, but would require some breaking changes. Now it's available on ./tests folder.
  • MIT license is more desirable than LGPLv3, since this project is intended for broad usage, so projects should not have to care about license on practice (which is not the case for LGPLv3)

For these reasons, code was rewritten with tests and new license, and legacy version will not be improved (it is considered deprecated).

An exception-less design

Exceptions are now deprecated, so every next() operation will return an optional output. This effectively removes the necessity of a hasNext() method, which we will still support if one prefers this kind of logic (note that output will still be optional, requiring operator*).

How to use

Example 1 (default separators)

#include <scannerpp/Scanner.hpp>

using namespace scannerpp;

int main() {
    // (1.a) Hello World
    Scanner scanner("Hello World");
    std::cout << scanner.next(); // returns "Hello"
    std::cout << scanner.next(); // returns "World"
    //
    // (1.b) Hello World
    Scanner scanner2("Hello World");
    while(scanner2.hasNext())
        std::cout << scanner2.next() << std::endl; // "Hello\nWorld"
    //
    // (1.c) Hello World
    Scanner scanner3("Hello World");
    std::string s;
    while ((s = scanner3.next()) != "")
        std::cout << s << std::endl; // "Hello\nWorld"
    //
    return 0;
}

Example 2 (other separators)

#include <scannerpp/Scanner.hpp>

using namespace scannerpp;

int main() {
    Scanner scanner("Hello;World");
    scanner.useSeparators(" ;\n\t"); // using semi-colon as separator too
    std::cout << scanner.next(); // returns "Hello"
    std::cout << scanner.next(); // returns "World"
    //
    return 0;
}

Example 3 (read from File or cin)

#include <scannerpp/Scanner.hpp>

using namespace scannerpp;

int main() {
    Scanner scanner(File("myfile.txt"));
    // 'myfile.txt' contains "Hello World" inside it
    std::cout << scanner.next(); // returns "Hello"
    std::cout << scanner.next(); // returns "World"
    Scanner scanner2(&cin); // passing 'cin' as pointer
    std::cout << scanner2.next() << std::endl; // blocks until user inputs data
    //
    return 0;
}

Example 4 (reading numbers)

#include <scannerpp/Scanner.hpp>

using namespace scannerpp;

int main() {
    Scanner scanner("-1 2147483647    2147483648    8589934592    3.14  8");
    // remember that 'nextInt()' returns std::optional, to prevent exceptions
    auto x1 = *scanner.nextInt();    // -1 (int)
    auto x2 = *scanner.nextInt();    // 2147483647 (int)  (no overflow)
    scanner.hasNextInt();            // -------> FALSE!
    auto x3 =  scanner.nextInt();    // this is 'nullopt' (overflow!)
    auto x4 = *scanner.nextLong();   // this is 8589934592 (long)
    auto x5 = *scanner.nextFloat();  // this is 3.14 (float)
    auto x6 = *scanner.nextDouble(); // this is 8.0 (double)
    printf("%d %d %s %ld %f %f\n", x1, x2, (x3==std::nullopt?"nullopt":""), x4, x5, x6);
    // outputs: -1 2147483647 nullopt 8589934592 3.140000 8.000000
    return 0;
}

Example 5 (reading numbers with c++17 if)

#include <scannerpp/Scanner.hpp>

using namespace scannerpp;

int main() {
    Scanner scanner("2147483647  2147483648");
    // Note that a c++17 'if' can efficiently declare and consume variables,
    //   as this completely avoids the need for 'hasNextInt' verification
    if(auto x2 = scanner.nextInt(); x2)
       printf("x2 is int = %d\n", *x2); // will print
    if(auto x3 = scanner.nextInt(); x3)
       printf("x3 is int = %d\n", *x3); // will not print
    //
    return 0;
}

How to Install

header-only copy

This is a header-only library. To keep it simple, just copy src/Scanner.hpp to your project and have fun! This way, you can just add #include "Scanner.hpp".

If you want to have it in your system, e.g. to use as #include <scannerpp/Scanner.hpp>, you need to do the following steps (next section).

System Installation

First, check if it passes all tests: make test and make test-coverage.

After, just type make install (this will require sudo). File will be installed on /usr/local/include/scannerpp.

After that, make test-install, should return:

g++ --std=c++17 test-install.cpp -o scannerpp_test_install
./scannerpp_test_install
Hello
World

License

MIT License

Copyleft, OptFrame group

2008-2020