Merge branch 'value-at'

README.md

@@ -454,6 +454,22 @@ class value {
 } // toml
 ```
 
+### `at()`
+
+You can access to the element of a table and an array by `toml::basic_value::at`.
+
+```cpp
+const toml::value v{1,2,3,4,5};
+std::cout << v.at(2).as_integer() << std::endl; // 3
+
+const toml::value v{{"foo", 42}, {"bar", 3.14}};
+std::cout << v.at("foo").as_integer() << std::endl; // 42
+```
+
+If an invalid key (integer for a table, string for an array), it throws
+`toml::type_error` for the conversion. If the provided key is out-of-range,
+it throws `std::out_of_range`.
+
 ## Checking value type
 
 You can check the type of a value by `is_xxx` function.

tests/test_value.cpp

@@ -905,3 +905,32 @@ BOOST_AUTO_TEST_CASE(test_value_empty)
     BOOST_CHECK_THROW(v1.as_array(),           toml::type_error);
     BOOST_CHECK_THROW(v1.as_table(),           toml::type_error);
 }
+
+
+BOOST_AUTO_TEST_CASE(test_value_at)
+{
+    {
+        toml::value v1{{"foo", 42}, {"bar", 3.14}, {"baz", "qux"}};
+
+        BOOST_TEST(v1.at("foo").as_integer()  == 42);
+        BOOST_TEST(v1.at("bar").as_floating() == 3.14);
+        BOOST_TEST(v1.at("baz").as_string()   == "qux");
+
+        BOOST_CHECK_THROW(v1.at(0), toml::type_error);
+        BOOST_CHECK_THROW(v1.at("quux"), std::out_of_range);
+    }
+
+
+    {
+        toml::value v1{1,2,3,4,5};
+
+        BOOST_TEST(v1.at(0).as_integer() == 1);
+        BOOST_TEST(v1.at(1).as_integer() == 2);
+        BOOST_TEST(v1.at(2).as_integer() == 3);
+        BOOST_TEST(v1.at(3).as_integer() == 4);
+        BOOST_TEST(v1.at(4).as_integer() == 5);
+
+        BOOST_CHECK_THROW(v1.at("foo"), toml::type_error);
+        BOOST_CHECK_THROW(v1.at(5),     std::out_of_range);
+    }
+}

toml/value.hpp

@@ -1567,6 +1567,28 @@ class basic_value
         return std::move(this->table_.value());
     }
 
+    // accessors =============================================================
+    //
+    // may throw type_error or out_of_range
+    //
+    value_type&       at(const key& k)
+    {
+        return this->as_table().at(k);
+    }
+    value_type const& at(const key& k) const
+    {
+        return this->as_table().at(k);
+    }
+
+    value_type&       at(const std::size_t idx)
+    {
+        return this->as_array().at(idx);
+    }
+    value_type const& at(const std::size_t idx) const
+    {
+        return this->as_array().at(idx);
+    }
+
     source_location location() const
     {
         return source_location(this->region_info_.get());