mkdocs: add operator<=> examples

docs/examples/operator_spaceship__const_reference.cpp

@@ -0,0 +1,41 @@
+#include <compare>
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+const char* to_string(const std::partial_ordering& po)
+{
+    if (std::is_lt(po))
+    {
+        return "less";
+    }
+    else if (std::is_gt(po))
+    {
+        return "greater";
+    }
+    else if (std::is_eq(po))
+    {
+        return "equivalent";
+    }
+    return "unordered";
+}
+
+int main()
+{
+    // create several JSON values
+    json array_1 = {1, 2, 3};
+    json array_2 = {1, 2, 4};
+    json object_1 = {{"A", "a"}, {"B", "b"}};
+    json object_2 = {{"B", "b"}, {"A", "a"}};
+    json number = 17;
+    json string = "foo";
+    json discarded = json(json::value_t::discarded);
+
+
+    // output values and comparisons
+    std::cout << array_1 << " <=> " << array_2 << " := " << to_string(array_1 <=> array_2) << '\n'; // *NOPAD*
+    std::cout << object_1 << " <=> " << object_2 << " := " << to_string(object_1 <=> object_2) << '\n'; // *NOPAD*
+    std::cout << string << " <=> " << number << " := " << to_string(string <=> number) << '\n'; // *NOPAD*
+    std::cout << string << " <=> " << discarded << " := " << to_string(string <=> discarded) << '\n'; // *NOPAD*
+}

docs/examples/operator_spaceship__const_reference.output

@@ -0,0 +1,4 @@
+[1,2,3] <=> [1,2,4] := less
+{"A":"a","B":"b"} <=> {"A":"a","B":"b"} := equivalent
+"foo" <=> 17 := greater
+"foo" <=> <discarded> := unordered

docs/examples/operator_spaceship__scalartype.cpp

@@ -0,0 +1,41 @@
+#include <compare>
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+const char* to_string(const std::partial_ordering& po)
+{
+    if (std::is_lt(po))
+    {
+        return "less";
+    }
+    else if (std::is_gt(po))
+    {
+        return "greater";
+    }
+    else if (std::is_eq(po))
+    {
+        return "equivalent";
+    }
+    return "unordered";
+}
+
+int main()
+{
+    using float_limits = std::numeric_limits<json::number_float_t>;
+    constexpr auto nan = float_limits::quiet_NaN();
+
+    // create several JSON values
+    json boolean = false;
+    json number = 17;
+    json string = "17";
+
+
+    // output values and comparisons
+    std::cout << std::boolalpha << std::fixed;
+    std::cout << boolean << " <=> " << true << " := " << to_string(boolean <=> true) << '\n'; // *NOPAD*
+    std::cout << number << " <=> " << 17.0 << " := " << to_string(number <=> 17.0) << '\n'; // *NOPAD*
+    std::cout << number << " <=> " << nan << " := " << to_string(number <=> nan) << '\n'; // *NOPAD*
+    std::cout << string << " <=> " << 17 << " := " << to_string(string <=> 17) << '\n'; // *NOPAD*
+}

docs/examples/operator_spaceship__scalartype.output

@@ -0,0 +1,4 @@
+false <=> true := less
+17 <=> 17.000000 := equivalent
+17 <=> nan := unordered
+"17" <=> 17 := greater

docs/mkdocs/docs/api/basic_json/operator_spaceship.md

@@ -55,6 +55,36 @@ Linear.
         2. Comparing a `NaN` with another `NaN`.
         3. Comparing a `NaN` and any other number.
 
+## Examples
+
+??? example "Example: (1) comparing JSON values"
+
+    The example demonstrates comparing several JSON values.
+    
+    ```cpp
+    --8<-- "examples/operator_spaceship__const_reference.cpp"
+    ```
+    
+    Output:
+    
+    ```json
+    --8<-- "examples/operator_spaceship__const_reference.output"
+    ```
+
+??? example "Example: (2) comparing JSON values and scalars"
+
+    The example demonstrates comparing several JSON values and scalars.
+    
+    ```cpp
+    --8<-- "examples/operator_spaceship__scalartype.cpp"
+    ```
+    
+    Output:
+    
+    ```json
+    --8<-- "examples/operator_spaceship__scalartype.output"
+    ```
+
 ## See also
 
 - [**operator==**](operator_eq.md) - comparison: equal