added prune() to table and array

CHANGELOG.md

@@ -37,6 +37,7 @@ code changes at callsites or in build systems are indicated with ⚠️.
 - added `operator->` to `toml::value` for class types
 - added `parse_benchmark` example
 - added `toml::array::at()` (same semantics as `std::vector::at()`)
+- added `toml::array::prune()`
 - added `toml::array::replace()` (#109) (@LebJe)
 - added `toml::array::resize()` param `default_init_flags`
 - added `toml::format_flags::allow_binary_integers`
@@ -50,6 +51,7 @@ code changes at callsites or in build systems are indicated with ⚠️.
 - added `toml::table::at()` (same semantics as `std::map::at()`)
 - added `toml::table::emplace_hint()` (same semantics as `std::map::emplace_hint()`)
 - added `toml::table::lower_bound()` (same semantics as `std::map::lower_bound()`)
+- added `toml::table::prune()`
 - added `toml::yaml_formatter`
 - added `TOML_ENABLE_FORMATTERS` option
 - added clang's enum annotation attributes to all enums

include/toml++/impl/array.h

@@ -1339,12 +1339,43 @@ TOML_NAMESPACE_START
 		/// \brief	 Flattens this array, recursively hoisting the contents of child arrays up into itself (rvalue overload).
 		///
 		/// \returns An rvalue reference to the array.
-		TOML_API
 		array&& flatten() &&
 		{
 			return static_cast<toml::array&&>(this->flatten());
 		}
 
+		/// \brief	Removes empty child arrays and tables.
+		///
+		/// \detail \cpp
+		///
+		/// auto arr = toml::array{ 1, 2, toml::array{ }, toml::array{ 3, toml::array{ } }, 4 };
+		/// std::cout << arr << "\n";
+		///
+		/// arr.prune();
+		/// std::cout << arr << "\n";
+		/// \ecpp
+		///
+		/// \out
+		/// [ 1, 2, [], [ 3, [] ], 4 ]
+		/// [ 1, 2, [ 3 ], 4 ]
+		/// \eout
+		///
+		/// \param recursive Should child arrays and tables themselves be pruned?
+		///
+		/// \returns A reference to the array.
+		TOML_API
+		array& prune(bool recursive = true) & noexcept;
+
+		/// \brief	Removes empty child arrays and tables (rvalue overload).
+		///
+		/// \param recursive Should child arrays and tables themselves be pruned?
+		///
+		/// \returns An rvalue reference to the array.
+		array&& prune(bool recursive = true) && noexcept
+		{
+			return static_cast<toml::array&&>(this->prune(recursive));
+		}
+
 		/// @}
 
 	  private:

include/toml++/impl/array.inl

@@ -243,6 +243,33 @@ TOML_NAMESPACE_START
 
 		return *this;
 	}
+
+	TOML_EXTERNAL_LINKAGE
+	array& array::prune(bool recursive)& noexcept
+	{
+		if (elems_.empty())
+			return *this;
+
+		for (size_t i = elems_.size(); i-- > 0u;)
+		{
+			if (auto arr = elems_[i]->as_array())
+			{
+				if (recursive)
+					arr->prune(true);
+				if (arr->empty())
+					elems_.erase(elems_.cbegin() + static_cast<ptrdiff_t>(i));
+			}
+			else if (auto tbl = elems_[i]->as_table())
+			{
+				if (recursive)
+					tbl->prune(true);
+				if (tbl->empty())
+					elems_.erase(elems_.cbegin() + static_cast<ptrdiff_t>(i));
+			}
+		}
+
+		return *this;
+	}
 }
 TOML_NAMESPACE_END;
 

include/toml++/impl/forward_declarations.h

@@ -98,7 +98,6 @@ TOML_NAMESPACE_START
 	class toml_formatter;
 	class json_formatter;
 	class yaml_formatter;
-	class xml_formatter;
 
 	TOML_ABI_NAMESPACE_BOOL(TOML_EXCEPTIONS, ex, noex);
 #if TOML_EXCEPTIONS

include/toml++/impl/table.h

@@ -1555,6 +1555,38 @@ TOML_NAMESPACE_START
 
 #endif // TOML_ENABLE_WINDOWS_COMPAT
 
+		/// \brief	Removes empty child arrays and tables.
+		///
+		/// \detail \cpp
+		///
+		/// auto tbl = toml::table{ { "a", 1 }, { "b", toml::array{ } }, { "c", toml::array{ toml::table{}, toml::array{} } } };
+		/// std::cout << arr << "\n";
+		///
+		/// arr.prune();
+		/// std::cout << arr << "\n";
+		/// \ecpp
+		///
+		/// \out
+		/// { a = 1, b = [], c = [ {}, [] ] }
+		/// { a = 1 }
+		/// \eout
+		///
+		/// \param recursive Should child arrays and tables themselves be pruned?
+		///
+		/// \returns A reference to the table.
+		TOML_API
+		table& prune(bool recursive = true) & noexcept;
+
+		/// \brief	Removes empty child arrays and tables (rvalue overload).
+		///
+		/// \param recursive Should child arrays and tables themselves be pruned?
+		///
+		/// \returns An rvalue reference to the table.
+		table&& prune(bool recursive = true) && noexcept
+		{
+			return static_cast<toml::table&&>(this->prune(recursive));
+		}
+
 		/// @}
 
 	  private:

include/toml++/impl/table.inl

@@ -204,6 +204,42 @@ TOML_NAMESPACE_START
 	{
 		return const_iterator{ map_.lower_bound(key) };
 	}
+
+	TOML_EXTERNAL_LINKAGE
+	table& table::prune(bool recursive)& noexcept
+	{
+		if (map_.empty())
+			return *this;
+
+		for (auto it = map_.begin(); it != map_.end();)
+		{
+			if (auto arr = it->second->as_array())
+			{
+				if (recursive)
+					arr->prune(true);
+
+				if (arr->empty())
+				{
+					it = map_.erase(it);
+					continue;
+				}
+			}
+			else if (auto tbl = it->second->as_table())
+			{
+				if (recursive)
+					tbl->prune(true);
+
+				if (tbl->empty())
+				{
+					it = map_.erase(it);
+					continue;
+				}
+			}
+			it++;
+		}
+
+		return *this;
+	}
 }
 TOML_NAMESPACE_END;
 

include/toml++/toml.h

@@ -34,6 +34,7 @@ TOML_DISABLE_SUGGEST_ATTR_WARNINGS;
 #include "impl/value.h"
 #include "impl/make_node.h"
 #include "impl/array.h"
+#include "impl/key.h"
 #include "impl/table.h"
 #include "impl/utf8.h"
 #include "impl/parse_error.h"

tests/manipulating_arrays.cpp

@@ -441,16 +441,16 @@ TEST_CASE("arrays - insertion and erasure")
 
 	arr.clear();
 	it = arr.insert(arr.cbegin(), L"test");
-	REQUIRE(*arr.get_as<std::string>(0u) == "test"sv);
+	CHECK(*arr.get_as<std::string>(0u) == "test"sv);
 
 	it = arr.emplace<std::string>(arr.cbegin(), L"test2"sv);
-	REQUIRE(*arr.get_as<std::string>(0u) == "test2"sv);
+	CHECK(*arr.get_as<std::string>(0u) == "test2"sv);
 
 	arr.push_back(L"test3"s);
-	REQUIRE(*arr.back().as_string() == "test3"sv);
+	CHECK(*arr.back().as_string() == "test3"sv);
 
 	arr.emplace_back<std::string>(L"test4");
-	REQUIRE(*arr.back().as_string() == "test4"sv);
+	CHECK(*arr.back().as_string() == "test4"sv);
 
 #endif // TOML_ENABLE_WINDOWS_COMPAT
 }
@@ -475,7 +475,7 @@ TEST_CASE("arrays - flattening")
 				   11 },
 		};
 		arr.flatten();
-		REQUIRE(arr == array{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 });
+		CHECK(arr == array{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 });
 	}
 
 	{
@@ -484,37 +484,53 @@ TEST_CASE("arrays - flattening")
 				   array{ array{}, array{ array{}, array{} }, array{} },
 				   array{ array{ array{ array{ array{ array{ 1 } } } } } } };
 		arr.flatten();
-		REQUIRE(arr == array{ 1 });
+		CHECK(arr == array{ 1 });
 	}
 }
 
+TEST_CASE("arrays - pruning")
+{
+	// [ 1, [ 2, [], 3 ], { 4 = 5, 6 = 7 }, [], 8, [{}], 9, 10 ]
+	const auto arr =
+		array{ 1, array{ 2, array{}, 3 }, table{ { "4", 5 }, { "6", array{} } }, array{}, 8, array{ table{} }, 9, 10 };
+
+	// [ 1, [ 2, 3 ], { 4 = 5, 6 = 7 }, 8, 9, 10 ]
+	const auto pruned_recursive = array{ 1, array{ 2, 3 }, table{ { "4", 5 } }, 8, 9, 10 };
+	CHECK(array{ arr }.prune(true) == pruned_recursive);
+
+	// [ 1, [ 2, [], 3 ], { 4 = 5, 6 = 7 }, [], 8, [{}], 9, 10 ]
+	const auto pruned_flat =
+		array{ 1, array{ 2, array{}, 3 }, table{ { "4", 5 }, { "6", array{} } }, 8, array{ table{} }, 9, 10 };
+	CHECK(array{ arr }.prune(false) == pruned_flat);
+}
+
 TEST_CASE("arrays - resizing and truncation")
 {
 	array arr{ 1, 2, 3, 4, 5 };
-	REQUIRE(arr.size() == 5u);
+	CHECK(arr.size() == 5u);
 
 	// truncate with no change
 	arr.truncate(5u);
-	REQUIRE(arr.size() == 5u);
-	REQUIRE(arr == array{ 1, 2, 3, 4, 5 });
+	CHECK(arr.size() == 5u);
+	CHECK(arr == array{ 1, 2, 3, 4, 5 });
 
 	// truncate down to three elements
 	arr.truncate(3u);
-	REQUIRE(arr.size() == 3u);
-	REQUIRE(arr == array{ 1, 2, 3 });
+	CHECK(arr.size() == 3u);
+	CHECK(arr == array{ 1, 2, 3 });
 
 	// resize down to two elements
 	arr.resize(2u, 42);
-	REQUIRE(arr.size() == 2u);
-	REQUIRE(arr == array{ 1, 2 });
+	CHECK(arr.size() == 2u);
+	CHECK(arr == array{ 1, 2 });
 
 	// resize with no change
 	arr.resize(2u, 42);
-	REQUIRE(arr.size() == 2u);
-	REQUIRE(arr == array{ 1, 2 });
+	CHECK(arr.size() == 2u);
+	CHECK(arr == array{ 1, 2 });
 
 	// resize up to six elements
 	arr.resize(6u, 42);
-	REQUIRE(arr.size() == 6u);
-	REQUIRE(arr == array{ 1, 2, 42, 42, 42, 42 });
+	CHECK(arr.size() == 6u);
+	CHECK(arr == array{ 1, 2, 42, 42, 42, 42 });
 }

toml.hpp

@@ -1112,7 +1112,6 @@ TOML_NAMESPACE_START
 	class toml_formatter;
 	class json_formatter;
 	class yaml_formatter;
-	class xml_formatter;
 
 	TOML_ABI_NAMESPACE_BOOL(TOML_EXCEPTIONS, ex, noex);
 #if TOML_EXCEPTIONS
@@ -5540,12 +5539,19 @@ TOML_NAMESPACE_START
 		TOML_API
 		array& flatten() &;
 
-		TOML_API
 		array&& flatten() &&
 		{
 			return static_cast<toml::array&&>(this->flatten());
 		}
 
+		TOML_API
+		array& prune(bool recursive = true) & noexcept;
+
+		array&& prune(bool recursive = true) && noexcept
+		{
+			return static_cast<toml::array&&>(this->prune(recursive));
+		}
+
 	  private:
 
 		TOML_NODISCARD
@@ -5625,12 +5631,8 @@ TOML_NAMESPACE_END;
 #endif
 TOML_POP_WARNINGS;
 
-//********  impl/table.h  **********************************************************************************************
+//********  impl/key.h  ************************************************************************************************
 
-TOML_DISABLE_WARNINGS;
-#include <map>
-#include <iterator>
-TOML_ENABLE_WARNINGS;
 TOML_PUSH_WARNINGS;
 #ifdef _MSC_VER
 #pragma push_macro("min")
@@ -5863,6 +5865,13 @@ TOML_IMPL_NAMESPACE_END;
 #pragma pop_macro("max")
 #endif
 TOML_POP_WARNINGS;
+
+//********  impl/table.h  **********************************************************************************************
+
+TOML_DISABLE_WARNINGS;
+#include <map>
+#include <iterator>
+TOML_ENABLE_WARNINGS;
 TOML_PUSH_WARNINGS;
 #ifdef _MSC_VER
 #pragma push_macro("min")
@@ -6779,6 +6788,14 @@ TOML_NAMESPACE_START
 
 #endif // TOML_ENABLE_WINDOWS_COMPAT
 
+		TOML_API
+		table& prune(bool recursive = true) & noexcept;
+
+		table&& prune(bool recursive = true) && noexcept
+		{
+			return static_cast<toml::table&&>(this->prune(recursive));
+		}
+
 	  private:
 
 		TOML_NODISCARD
@@ -9770,6 +9787,33 @@ TOML_NAMESPACE_START
 
 		return *this;
 	}
+
+	TOML_EXTERNAL_LINKAGE
+	array& array::prune(bool recursive)& noexcept
+	{
+		if (elems_.empty())
+			return *this;
+
+		for (size_t i = elems_.size(); i-- > 0u;)
+		{
+			if (auto arr = elems_[i]->as_array())
+			{
+				if (recursive)
+					arr->prune(true);
+				if (arr->empty())
+					elems_.erase(elems_.cbegin() + static_cast<ptrdiff_t>(i));
+			}
+			else if (auto tbl = elems_[i]->as_table())
+			{
+				if (recursive)
+					tbl->prune(true);
+				if (tbl->empty())
+					elems_.erase(elems_.cbegin() + static_cast<ptrdiff_t>(i));
+			}
+		}
+
+		return *this;
+	}
 }
 TOML_NAMESPACE_END;
 
@@ -9978,6 +10022,42 @@ TOML_NAMESPACE_START
 	{
 		return const_iterator{ map_.lower_bound(key) };
 	}
+
+	TOML_EXTERNAL_LINKAGE
+	table& table::prune(bool recursive)& noexcept
+	{
+		if (map_.empty())
+			return *this;
+
+		for (auto it = map_.begin(); it != map_.end();)
+		{
+			if (auto arr = it->second->as_array())
+			{
+				if (recursive)
+					arr->prune(true);
+
+				if (arr->empty())
+				{
+					it = map_.erase(it);
+					continue;
+				}
+			}
+			else if (auto tbl = it->second->as_table())
+			{
+				if (recursive)
+					tbl->prune(true);
+
+				if (tbl->empty())
+				{
+					it = map_.erase(it);
+					continue;
+				}
+			}
+			it++;
+		}
+
+		return *this;
+	}
 }
 TOML_NAMESPACE_END;