FetchContent example

.gitignore

@@ -36,3 +36,6 @@
 
 # Development stuff
 .direnv
+
+# Vim
+*.swp

README.rst

@@ -6,4 +6,39 @@ cpp-parselglossy
         :target: https://travis-ci.org/dev-cafe/cpp-parselglossy
         :alt: Linux build status
 
-Example of using parselglossy with a C++ project
+This repo contains a simple example of how to use ``parselglossy`` in a C++
+project using two different CMake setups: externalproject and fetchcontent.
+The code example is identical in the two setups.
+
+To install ``parselglossy`` through pipenv using the provided Pipfile:
+
+.. code:: bash
+
+    $ cd cpp-parselglossy
+    $ pipenv install
+    $ pipenv shell
+
+To configure and build the ``fetchcontent`` example (identical for ``externalproject``):
+
+.. code:: bash
+
+    $ cd fetchcontent
+    $ mkdir build
+    $ cmake -H. -Bbuild
+    $ cd build
+    $ make
+
+To run the test suite:
+
+.. code:: bash
+
+    $ cd build
+    $ ctest
+
+To run example:
+
+.. code:: bash
+
+    $ cd examples
+    $ parselglossy parse --outfile=throw_darts.json --template=../build/share/template.yml --grammar=getkw throw_darts.inp
+    $ ../build/bin/pi throw_darts.json

fetchcontent/CMakeLists.txt

@@ -8,4 +8,40 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 include(${PROJECT_SOURCE_DIR}/external/upstream/fetch_nlohmann_json.cmake)
 
+message(STATUS "Project will be installed to ${CMAKE_INSTALL_PREFIX}")
+
+if(NOT CMAKE_BUILD_TYPE)
+  set(CMAKE_BUILD_TYPE Release CACHE STRING "Build type" FORCE)
+endif()
+
+message(STATUS "Build type set to ${CMAKE_BUILD_TYPE}")
+
+include(GNUInstallDirs)
+
+set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR})
+set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR})
+set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/${CMAKE_INSTALL_BINDIR})
+
+# Offer the user the choice of overriding the installation directories
+set(INSTALL_LIBDIR ${CMAKE_INSTALL_LIBDIR} CACHE PATH "Installation directory for libraries")
+set(INSTALL_BINDIR ${CMAKE_INSTALL_BINDIR} CACHE PATH "Installation directory for executables")
+set(INSTALL_INCLUDEDIR ${CMAKE_INSTALL_INCLUDEDIR} CACHE PATH "Installation directory for header files")
+if(WIN32 AND NOT CYGWIN)
+  set(DEF_INSTALL_CMAKEDIR CMake)
+else()
+  set(DEF_INSTALL_CMAKEDIR share/cmake/${PROJECT_NAME})
+endif()
+set(INSTALL_CMAKEDIR ${DEF_INSTALL_CMAKEDIR} CACHE PATH "Installation directory for CMake files")
+
+# Report to user
+foreach(p LIB BIN INCLUDE CMAKE)
+  file(TO_NATIVE_PATH ${CMAKE_INSTALL_PREFIX}/${INSTALL_${p}DIR} _path )
+  message(STATUS "Installing ${p} components to ${_path}")
+  unset(_path)
+endforeach()
+
 add_subdirectory(src)
+
+enable_testing()
+include(CTest)
+add_subdirectory(tests)

fetchcontent/examples/integration.inp

@@ -0,0 +1,7 @@
+title = "This program computes Pi"
+method = integration
+
+Integration {
+  n_steps = 10**4
+}
+

fetchcontent/examples/throw_darts.inp

@@ -0,0 +1,8 @@
+title = "This program computes Pi"
+method = darts
+
+Darts {
+  n_darts = 10**4
+  random_seed = 1
+}
+

fetchcontent/external/upstream/fetch_nlohmann_json.cmake

@@ -1,6 +1,6 @@
 find_package(nlohmann_json 3.5.0 CONFIG QUIET)
 
-if(TARGET nlohmann_json::nlhomann_json)
+if(TARGET nlohmann_json::nlohmann_json)
   get_target_property(
     _loc
     nlohmann_json::nlohmann_json

fetchcontent/src/CMakeLists.txt

@@ -1,6 +1,48 @@
-add_executable(example example.cpp)
+add_executable(pi pi.cpp)
 
-target_link_libraries(example
+target_link_libraries(pi
   PRIVATE
     nlohmann_json::nlohmann_json
   )
+
+# RPATH fixing
+file(RELATIVE_PATH _rel ${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_BINDIR} ${CMAKE_INSTALL_PREFIX})
+if(APPLE)
+  set(_rpath "@loader_path/${_rel}")
+else()
+  set(_rpath "\$ORIGIN/${_rel}")
+endif()
+file(TO_NATIVE_PATH "${_rpath}/${CMAKE_INSTALL_LIBDIR}" Pi_RPATH)
+
+set_target_properties(pi
+  PROPERTIES
+    MACOSX_RPATH ON
+    SKIP_BUILD_RPATH OFF
+    BUILD_WITH_INSTALL_RPATH OFF
+    INSTALL_RPATH "${Pi_RPATH}"
+    INSTALL_RPATH_USE_LINK_PATH ON
+  )
+
+install(
+  TARGETS
+    pi
+  RUNTIME
+    DESTINATION ${CMAKE_INSTALL_BINDIR}
+    COMPONENT bin
+  )
+
+
+file(
+  COPY
+    template.yml
+  DESTINATION
+    ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_DATADIR}
+  )
+
+install(
+  FILES
+    ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_DATADIR}/template.yml
+  DESTINATION
+    ${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_DATADIR}
+  )
+

fetchcontent/src/pi.cpp

@@ -0,0 +1,103 @@
+#include <iostream>
+#include <iomanip>
+#include <fstream>
+#include <string>
+#include <random>
+
+#include "nlohmann/json.hpp"
+
+using json = nlohmann::json;
+
+int fetch_input(int argc, char **argv, json &input);
+void integration(const json &input, json &output);
+void throw_darts(const json &input, json &output);
+
+int main(int argc, char **argv) {
+    // Read JSON input
+    json inp_json;
+    if (fetch_input(argc, argv, inp_json)) return EXIT_FAILURE;
+
+    // Prepare JSON output
+    json out_json;
+    out_json["title"] = inp_json["title"];
+
+    // Fetch computation method from input
+    auto method = inp_json["method"].get<std::string>();
+    if (method == "integration") {
+        const auto &int_json = inp_json["Integration"].get<json>();
+        integration(int_json, out_json);
+    }
+    if (method == "darts") {
+        const auto &dart_json = inp_json["Darts"].get<json>();
+        throw_darts(dart_json, out_json);
+    }
+
+    // Dump JSON input
+    std::cout << "\n-------------- JSON input -----------------\n";
+    std::cout << inp_json.dump(2) << std::endl;
+    std::cout << "-------------------------------------------\n";
+
+    // Dump JSON output
+    std::cout << "\n-------------- JSON output ----------------\n";
+    std::cout << out_json.dump(2) << std::endl;
+    std::cout << "-------------------------------------------\n\n";
+
+    return EXIT_SUCCESS;
+}
+
+int fetch_input(int argc, char **argv, json &input) {
+    if (argc != 2) {
+        std::cout << "Wrong number of arguments!" << std::endl;
+        return 1;
+    }
+
+    std::ifstream ifs(argv[1], std::ios_base::in);
+    if (ifs.fail()) {
+        std::cout << "Failed to open file!" << std::endl;
+        return 1;
+    }
+
+    ifs >> input;
+    ifs.close();
+
+    return 0;
+}
+
+void integration(const json &input, json &output) {
+    auto n_steps = input["n_steps"].get<int>();
+    auto step = 1.0 / n_steps;
+
+    auto sum = 0.0;
+    for (auto i = 0; i < n_steps; i++) {
+        auto x = (i + 0.5) * step;
+        auto f_x = 1.0 / (1.0 + x * x);
+        sum += step * f_x;
+    }
+
+    output["method"] = "Numerical integration";
+    output["pi"] = 4.0 * sum;
+}
+
+void throw_darts(const json &input, json &output) {
+    auto n_darts = input["n_darts"].get<int>();
+    auto seed = input["random_seed"].get<int>();
+
+    // Seed the random number generator
+    std::mt19937 rand_en(seed);
+    std::uniform_real_distribution<> uniform_dist(0.0, 1.0);
+
+    auto n_hits = 0;
+    for (auto i = 0; i < n_darts; i++) {
+        //creates 2 random numbers between 0 and 1
+        auto x = uniform_dist(rand_en);
+        auto y = uniform_dist(rand_en);
+        auto r = std::sqrt(x*x + y*y);
+
+        //counts how often the dart hits the circle
+        if (r <= 1.0) n_hits++;
+    }
+
+    output["method"] = "Throwing darts";
+    output["pi"] = 4.0 * n_hits / n_darts;
+}
+

fetchcontent/src/template.yml

@@ -0,0 +1,44 @@
+keywords:
+  - name: title
+    type: str
+    docstring: |
+      Please provide a title of the calculation to display in the beginning.
+  - name: method
+    type: str
+    predicates:
+      - "value == 'integration' or value == 'darts'"
+    docstring: |
+      Choose which method to use, numerical integration or throwing darts.
+sections:
+  - name: Integration
+    docstring: |
+      Section giving details on the numerical integration method.
+    keywords:
+      - name: n_steps
+        type: int
+        default: 1000
+        predicates:
+          - 'value > 0'
+          - 'value < 1000000'
+        docstring: |
+          Number of intervals in the numerical integration. Larger number means higher accuracy.
+  - name: Darts
+    docstring: |
+      Section giving details on the dart throwing method.
+    keywords:
+      - name: n_darts
+        type: int
+        default: 1000
+        predicates:
+          - 'value > 0'
+          - 'value < 1000000'
+        docstring: |
+          Number of darts to throw. Larger number means higher accuracy.
+      - name: random_seed
+        type: int
+        default: 0
+        predicates:
+          - 'value >= 0'
+          - 'value < 2**32'
+        docstring: |
+          Number used as seed in the pseudo-random number generator.

fetchcontent/tests/CMakeLists.txt

@@ -0,0 +1,5 @@
+# Integration tests
+add_subdirectory(darts)
+add_subdirectory(darts_default)
+add_subdirectory(integration)
+add_subdirectory(integration_default)

fetchcontent/tests/darts/CMakeLists.txt

@@ -0,0 +1,25 @@
+execute_process(
+  COMMAND
+    cmake -E create_symlink
+    "${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_DATADIR}/template.yml" # Old name
+    "${CMAKE_CURRENT_BINARY_DIR}/template.yml" # New name
+  )
+
+file(
+  COPY
+    pi.inp
+  DESTINATION
+    ${CMAKE_CURRENT_BINARY_DIR}
+  )
+
+add_test(
+  NAME
+    darts
+  COMMAND
+    ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_LIST_DIR}/test
+    --binary=${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_BINDIR}
+    --work-dir=${CMAKE_CURRENT_BINARY_DIR}
+    --verbose
+  WORKING_DIRECTORY
+    ${CMAKE_CURRENT_BINARY_DIR}
+  )

fetchcontent/tests/darts/pi.inp

@@ -0,0 +1,8 @@
+title = "This program computes Pi"
+method = darts
+
+Darts {
+  n_darts = 100000
+  random_seed = 225512
+}
+