adds examples.cpp to assist with documentation

Author: attwoodn

tests/CMakeLists.txt

@@ -20,4 +20,9 @@ if(BUILD_TESTING)
     target_compile_options( expression_tree_test PRIVATE -fsanitize=address )
     add_test( expression_tree_test ${EXECUTABLE_OUTPUT_PATH}/expression_tree_test )
 
+    add_executable( examples examples.cpp )
+    target_link_libraries( examples "-fsanitize=address" )
+    target_compile_options( examples PRIVATE -fsanitize=address )
+    add_test( examples ${EXECUTABLE_OUTPUT_PATH}/examples )
+
 endif()

tests/examples.cpp

@@ -0,0 +1,44 @@
+#include <attwoodn/expression_tree.hpp>
+#include <cassert>
+
+using namespace attwoodn::expression_tree;
+
+void expression_memory_safety_example();
+
+struct my_type {
+   int my_int = 5;
+   bool my_bool = true;
+};
+
+int main(int argc, char** argv) {
+    expression_memory_safety_example();
+
+    return EXIT_SUCCESS;
+}
+
+void expression_memory_safety_example() {
+    // The heap-allocated expression node pointer returned by make_expr becomes owned by the expression_tree
+    expression_tree<my_type> expr_tree_raw {
+        make_expr(&my_type::my_bool, op::equals, true)
+    };
+
+
+    // ...
+
+
+    // The heap-allocated expression node pointer returned by make_expr becomes owned by the unique_ptr
+    std::unique_ptr<node::expression_tree_node<my_type>> smart_expr {
+        make_expr(&my_type::my_bool, op::equals, true)
+    };
+
+    // the expression_tree takes ownership of the unique_ptr
+    expression_tree<my_type> expr_tree_smart(std::move(smart_expr));
+
+
+    // ...
+
+
+    // The heap-allocated expression node pointer returned by make_expr must be explicitly deleted
+    auto* expr_raw = make_expr(&my_type::my_bool, op::equals, true);
+    delete expr_raw;
+}

tests/expression_tree.cpp

@@ -4,12 +4,14 @@
 
 using namespace attwoodn::expression_tree;
 
+void test_expression_tree_std_string_template();
 void test_simple_expression_tree();
 void test_complex_expression_tree();
 void test_moved_expression_tree();
 void test_copied_expression_tree();
 
 int main(int argc, char** argv) {
+    test_expression_tree_std_string_template();
     test_simple_expression_tree();
     test_complex_expression_tree();
     test_moved_expression_tree();
@@ -18,6 +20,17 @@ int main(int argc, char** argv) {
     return EXIT_SUCCESS;
 }
 
+void test_expression_tree_std_string_template() {
+    expression_tree<std::string> expr {
+        make_expr(&std::string::empty, op::equals, true)
+    };
+
+    assert(expr.evaluate(""));
+    assert(!expr.evaluate(" "));
+    assert(!expr.evaluate("hello"));
+    assert(!expr.evaluate("good bye"));
+}
+
 void test_simple_expression_tree() {
     auto test_procedure = [](const expression_tree<test_fixture>& expr) {
         test_fixture fixture;