Help/guide/tutorial: Adopt tutorial code

8 files changed, 292 insertions, 0 deletions

diff --git a/Help/guide/tutorial/Step6/CMakeLists.txt b/Help/guide/tutorial/Step6/CMakeLists.txt
new file mode 100644
index 0000000..a78b0ff
--- /dev/null
+++ b/Help/guide/tutorial/Step6/CMakeLists.txt
@@ -0,0 +1,75 @@
+cmake_minimum_required(VERSION 3.3)
+project(Tutorial)
+
+set(CMAKE_CXX_STANDARD 14)
+
+# the version number.
+set(Tutorial_VERSION_MAJOR 1)
+set(Tutorial_VERSION_MINOR 0)
+
+# does this system provide the log and exp functions?
+include(CheckSymbolExists)
+set(CMAKE_REQUIRED_LIBRARIES "m")
+check_symbol_exists(log "math.h" HAVE_LOG)
+check_symbol_exists(exp "math.h" HAVE_EXP)
+
+# should we use our own math functions
+option(USE_MYMATH "Use tutorial provided math implementation" ON)
+
+# configure a header file to pass some of the CMake settings
+# to the source code
+configure_file(
+  "${PROJECT_SOURCE_DIR}/TutorialConfig.h.in"
+  "${PROJECT_BINARY_DIR}/TutorialConfig.h"
+  )
+
+# add the MathFunctions library?
+if(USE_MYMATH)
+  add_subdirectory(MathFunctions)
+  list(APPEND EXTRA_LIBS MathFunctions)
+endif()
+
+# add the executable
+add_executable(Tutorial tutorial.cxx)
+target_link_libraries(Tutorial PUBLIC ${EXTRA_LIBS})
+
+# add the binary tree to the search path for include files
+# so that we will find TutorialConfig.h
+target_include_directories(Tutorial PUBLIC
+                           "${PROJECT_BINARY_DIR}"
+                           )
+
+# add the install targets
+install(TARGETS Tutorial DESTINATION bin)
+install(FILES "${PROJECT_BINARY_DIR}/TutorialConfig.h"
+  DESTINATION include
+  )
+
+# enable testing
+enable_testing()
+
+# does the application run
+add_test(NAME Runs COMMAND Tutorial 25)
+
+# does the usage message work?
+add_test(NAME Usage COMMAND Tutorial)
+set_tests_properties(Usage
+  PROPERTIES PASS_REGULAR_EXPRESSION "Usage:.*number"
+  )
+
+# define a function to simplify adding tests
+function(do_test target arg result)
+  add_test(NAME Comp${arg} COMMAND ${target} ${arg})
+  set_tests_properties(Comp${arg}
+    PROPERTIES PASS_REGULAR_EXPRESSION ${result}
+    )
+endfunction(do_test)
+
+# do a bunch of result based tests
+do_test(Tutorial 4 "4 is 2")
+do_test(Tutorial 9 "9 is 3")
+do_test(Tutorial 5 "5 is 2.236")
+do_test(Tutorial 7 "7 is 2.645")
+do_test(Tutorial 25 "25 is 5")
+do_test(Tutorial -25 "-25 is [-nan|nan|0]")
+do_test(Tutorial 0.0001 "0.0001 is 0.01")
diff --git a/Help/guide/tutorial/Step6/MathFunctions/CMakeLists.txt b/Help/guide/tutorial/Step6/MathFunctions/CMakeLists.txt
new file mode 100644
index 0000000..2946075
--- /dev/null
+++ b/Help/guide/tutorial/Step6/MathFunctions/CMakeLists.txt
@@ -0,0 +1,14 @@
+add_library(MathFunctions mysqrt.cxx)
+
+# state that anybody linking to us needs to include the current source dir
+# to find MathFunctions.h, while we don't.
+# state that we depend on Tutorial_BINARY_DIR but consumers don't, as the
+# TutorialConfig.h include is an implementation detail
+
+target_include_directories(MathFunctions
+          INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
+          PRIVATE ${Tutorial_BINARY_DIR}
+          )
+
+install(TARGETS MathFunctions DESTINATION lib)
+install(FILES MathFunctions.h DESTINATION include)
diff --git a/Help/guide/tutorial/Step6/MathFunctions/MakeTable.cxx b/Help/guide/tutorial/Step6/MathFunctions/MakeTable.cxx
new file mode 100644
index 0000000..ee58556
--- /dev/null
+++ b/Help/guide/tutorial/Step6/MathFunctions/MakeTable.cxx
@@ -0,0 +1,25 @@
+// A simple program that builds a sqrt table
+#include <cmath>
+#include <fstream>
+#include <iostream>
+
+int main(int argc, char* argv[])
+{
+  // make sure we have enough arguments
+  if (argc < 2) {
+    return 1;
+  }
+
+  std::ofstream fout(argv[1], std::ios_base::out);
+  const bool fileOpen = fout.is_open();
+  if (fileOpen) {
+    fout << "double sqrtTable[] = {" << std::endl;
+    for (int i = 0; i < 10; ++i) {
+      fout << sqrt(static_cast<double>(i)) << "," << std::endl;
+    }
+    // close the table with a zero
+    fout << "0};" << std::endl;
+    fout.close();
+  }
+  return fileOpen ? 0 : 1; // return 0 if wrote the file
+}
diff --git a/Help/guide/tutorial/Step6/MathFunctions/MathFunctions.h b/Help/guide/tutorial/Step6/MathFunctions/MathFunctions.h
new file mode 100644
index 0000000..cd36bcc
--- /dev/null
+++ b/Help/guide/tutorial/Step6/MathFunctions/MathFunctions.h
@@ -0,0 +1 @@
+double mysqrt(double x);
diff --git a/Help/guide/tutorial/Step6/MathFunctions/mysqrt.cxx b/Help/guide/tutorial/Step6/MathFunctions/mysqrt.cxx
new file mode 100644
index 0000000..b9ad20a
--- /dev/null
+++ b/Help/guide/tutorial/Step6/MathFunctions/mysqrt.cxx
@@ -0,0 +1,33 @@
+#include "MathFunctions.h"
+#include "TutorialConfig.h"
+#include <iostream>
+
+#include <cmath>
+
+// a hack square root calculation using simple operations
+double mysqrt(double x)
+{
+  if (x <= 0) {
+    return 0;
+  }
+
+  // if we have both log and exp then use them
+#if defined(HAVE_LOG) && defined(HAVE_EXP)
+  double result = exp(log(x) * 0.5);
+  std::cout << "Computing sqrt of " << x << " to be " << result << " using log"
+            << std::endl;
+#else
+  double result = x;
+
+  // do ten iterations
+  for (int i = 0; i < 10; ++i) {
+    if (result <= 0) {
+      result = 0.1;
+    }
+    double delta = x - (result * result);
+    result = result + 0.5 * delta / result;
+    std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
+  }
+#endif
+  return result;
+}
diff --git a/Help/guide/tutorial/Step6/TutorialConfig.h.in b/Help/guide/tutorial/Step6/TutorialConfig.h.in
new file mode 100644
index 0000000..e97ce24
--- /dev/null
+++ b/Help/guide/tutorial/Step6/TutorialConfig.h.in
@@ -0,0 +1,8 @@
+// the configured options and settings for Tutorial
+#define Tutorial_VERSION_MAJOR @Tutorial_VERSION_MAJOR@
+#define Tutorial_VERSION_MINOR @Tutorial_VERSION_MINOR@
+#cmakedefine USE_MYMATH
+
+// does the platform provide exp and log functions?
+#cmakedefine HAVE_LOG
+#cmakedefine HAVE_EXP
diff --git a/Help/guide/tutorial/Step6/directions.txt b/Help/guide/tutorial/Step6/directions.txt
new file mode 100644
index 0000000..42b9f06
--- /dev/null
+++ b/Help/guide/tutorial/Step6/directions.txt
@@ -0,0 +1,104 @@
+# Adding a Custom Command and Generated File #
+
+In this section we will show how you can add a generated source file into the
+build process of an application. For this example, we will create a table of
+precomputed square roots as part of the build process, and then compile that
+table into our application.
+
+To accomplish this, we first need a program that will generate the table. In the
+MathFunctions subdirectory a new source file named MakeTable.cxx will do just that.
+
+  // A simple program that builds a sqrt table
+  #include <iostream>
+  #include <fstream>
+  #include <cmath>
+
+  int main (int argc, char *argv[])
+  {
+    // make sure we have enough arguments
+    if (argc < 2) {
+      return 1;
+    }
+
+    std::ofstream fout(argv[1],std::ios_base::out);
+    const bool fileOpen = fout.is_open();
+    if(fileOpen) {
+      fout << "double sqrtTable[] = {" << std::endl;
+      for (int i = 0; i < 10; ++i) {
+        fout << sqrt(static_cast<double>(i)) << "," << std::endl;
+      }
+      // close the table with a zero
+      fout << "0};" << std::endl;
+      fout.close();
+    }
+    return fileOpen ? 0 : 1; // return 0 if wrote the file
+  }
+
+Note that the table is produced as valid C++ code and that the output filename
+is passed in as an argument.
+
+The next step is to add the appropriate commands to MathFunctions’ CMakeLists
+file to build the MakeTable executable and then run it as part of the build
+process. A few commands are needed to accomplish this, as shown below:
+
+  # first we add the executable that generates the table
+  add_executable(MakeTable MakeTable.cxx)
+
+  # add the command to generate the source code
+  add_custom_command(
+    OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/Table.h
+    COMMAND MakeTable ${CMAKE_CURRENT_BINARY_DIR}/Table.h
+    DEPENDS MakeTable
+    )
+
+  # add the main library
+  add_library(MathFunctions
+              mysqrt.cxx
+              ${CMAKE_CURRENT_BINARY_DIR}/Table.h
+              )
+
+  target_include_directories(MathFunctions
+          INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
+          PUBLIC ${Tutorial_BINARY_DIR}
+                 # add the binary tree directory to the search path for include files
+                 ${CMAKE_CURRENT_BINARY_DIR}
+          )
+
+  install(TARGETS MathFunctions DESTINATION lib)
+  install(FILES MathFunctions.h DESTINATION include)
+
+First, the executable for MakeTable is added as any other executable would be
+added. Then we add a custom command that specifies how to produce Table.h by
+running MakeTable. Next we have to let CMake know that mysqrt.cxx depends on
+the generated file Table.h. This is done by adding the generated Table.h to the
+list of sources for the library MathFunctions. We also have to add the current
+binary directory to the list of include directories so that Table.h can be
+found and included by mysqrt.cxx.
+
+Now let's use the generated table. First, modify mysqrt.cxx to include Table.h.
+Next, we can rewrite the mysqrt function to use the table:
+
+  if (x <= 0) {
+    return 0;
+  }
+
+  // use the table to help find an initial value
+  double result = x;
+  if (x >= 1 && x < 10) {
+    result = sqrtTable[static_cast<int>(x)];
+  }
+
+  // do ten iterations
+  for (int i = 0; i < 10; ++i) {
+    if (result <= 0) {
+      result = 0.1;
+    }
+    double delta = x - (result*result);
+    result = result + 0.5*delta/result;
+    std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
+  }
+
+Run cmake or cmake-gui to configure the project and then build it with your
+chosen build tool. When this project is built it will first build the MakeTable
+executable. It will then run MakeTable to produce Table.h. Finally, it will
+compile mysqrt.cxx which includes Table.h to produce the MathFunctions library.
diff --git a/Help/guide/tutorial/Step6/tutorial.cxx b/Help/guide/tutorial/Step6/tutorial.cxx
new file mode 100644
index 0000000..c2b89df
--- /dev/null
+++ b/Help/guide/tutorial/Step6/tutorial.cxx
@@ -0,0 +1,32 @@
+// A simple program that computes the square root of a number
+#include <cmath>
+#include <iostream>
+#include <string>
+
+#include "TutorialConfig.h"
+
+#ifdef USE_MYMATH
+#  include "MathFunctions.h"
+#endif
+
+int main(int argc, char* argv[])
+{
+  if (argc < 2) {
+    std::cout << argv[0] << " Version " << Tutorial_VERSION_MAJOR << "."
+              << Tutorial_VERSION_MINOR << std::endl;
+    std::cout << "Usage: " << argv[0] << " number" << std::endl;
+    return 1;
+  }
+
+  double inputValue = std::stod(argv[1]);
+
+#ifdef USE_MYMATH
+  double outputValue = mysqrt(inputValue);
+#else
+  double outputValue = sqrt(inputValue);
+#endif
+
+  std::cout << "The square root of " << inputValue << " is " << outputValue
+            << std::endl;
+  return 0;
+}