added toml_merger example

closes #155

README.md

@@ -280,6 +280,7 @@ UTF-8 decoding is performed using a state machine based on Bjoern Hoehrmann's '[
 # Contact
 For bug reports and feature requests please consider using the [issues] system here on GitHub. For anything else
 though you're welcome to reach out via other means. In order of likely response time:
+- Gitter: [marzer/tomlplusplus](https://gitter.im/marzer/tomlplusplus) ("Discord for repos")
 - Twitter: [marzer8789](https://twitter.com/marzer8789)
 - Email: [mark.gillard@outlook.com.au](mailto:mark.gillard@outlook.com.au)
 - Facebook: [marzer](https://www.facebook.com/marzer)

docs/pages/main_page.dox

@@ -591,6 +591,7 @@ it is embedded in the preamble at the top of the header.
 \section mainpage-contact Contacting the author
 For bug reports and feature requests please use the \github{marzer/tomlplusplus/issues, Github Issues}
 system. For anything else you're welcome to reach out via other means. In order of likely response speed:
+- Gitter: [marzer/tomlplusplus](https://gitter.im/marzer/tomlplusplus) ("Discord for repos")
 - Twitter: [marzer8789](https://twitter.com/marzer8789)
 - Email: [mark.gillard@outlook.com.au](mailto:mark.gillard@outlook.com.au)
 - Facebook: [marzer](https://www.facebook.com/marzer)

examples/CMakeLists.txt

@@ -21,6 +21,7 @@ endfunction()
 
 add_example(error_printer)
 add_example(parse_benchmark)
-add_example(simple_parser ARGS "${PROJECT_SOURCE_DIR}/example.toml")
+add_example(simple_parser)
-add_example(toml_generator ARGS 100)
+add_example(toml_generator)
+add_example(toml_merger)
 add_example(toml_to_json_transcoder ARGS "${PROJECT_SOURCE_DIR}/example.toml")

examples/merge_base.toml

@@ -0,0 +1,5 @@
+[section1]
+key1="value1"
+key2="value2"
+
+[section1.child1]

examples/merge_overrides.toml

@@ -0,0 +1,8 @@
+[section1]
+key2="value3"
+
+[section1.child1]
+foo="bar"
+
+[section1.child2]
+foo2="bar2"

examples/meson.build

@@ -23,6 +23,7 @@ examples = [
 	'toml_generator',
 	'error_printer',
 	'parse_benchmark',
+	'toml_merger',
 ]
 
 example_executables = []

examples/toml_merger.cpp

@@ -0,0 +1,69 @@
+// This file is a part of toml++ and is subject to the the terms of the MIT license.
+// Copyright (c) Mark Gillard <mark.gillard@outlook.com.au>
+// See https://github.com/marzer/tomlplusplus/blob/master/LICENSE for the full license text.
+// SPDX-License-Identifier: MIT
+
+// This example demonstrates a method of merging one TOML data tree into another.
+
+#include "examples.h"
+#include <toml++/toml.h>
+
+using namespace std::string_view_literals;
+
+namespace
+{
+	// recursively merge 'rhs' into 'lhs'.
+	//
+	// note that this implementation always prioritizes 'rhs' over 'lhs' in the event of a conflict;
+	// extending it to handle conflicts in some other manner is left as an exercise to the reader :)
+
+	static void merge(toml::table& lhs, toml::table&& rhs)
+	{
+		rhs.for_each(
+			[&](const toml::key& rhs_key, auto&& rhs_val)
+			{
+				auto lhs_it = lhs.lower_bound(rhs_key);
+
+				// not found in lhs - direct move
+				if (lhs_it == lhs.cend() || lhs_it->first != rhs_key)
+				{
+					lhs.emplace_hint(lhs_it, rhs_key, std::move(rhs_val));
+					return;
+				}
+
+				// both nodes were tables -  recurse into them
+				if constexpr (toml::is_table<decltype(rhs_val)>)
+				{
+					if (auto lhs_child_table = lhs_it->second.as_table())
+					{
+						merge(*lhs_child_table, std::move(rhs_val));
+						return;
+					}
+				}
+
+				// one or both weren't tables - replace lhs with rhs
+				lhs.insert_or_assign(rhs_key, std::move(rhs_val));
+			});
+	}
+}
+
+int main(int argc, char** argv)
+{
+	const auto base_path	  = argc > 1 ? std::string_view{ argv[1] } : "merge_base.toml"sv;
+	const auto overrides_path = argc > 2 ? std::string_view{ argv[2] } : "merge_overrides.toml"sv;
+
+	toml::table tbl;
+	try
+	{
+		tbl = toml::parse_file(base_path);
+		merge(tbl, toml::parse_file(overrides_path));
+	}
+	catch (const toml::parse_error& err)
+	{
+		std::cerr << err << "\n";
+		return 1;
+	}
+
+	std::cout << tbl << "\n";
+	return 0;
+}

examples/toml_merger.vcxproj

@@ -0,0 +1,63 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|x64">
+      <Configuration>Debug</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|x64">
+      <Configuration>Release</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+  </ItemGroup>
+  <PropertyGroup Label="Globals">
+    <VCProjectVersion>16.0</VCProjectVersion>
+    <ProjectGuid>{E467EB97-B066-4D38-B3DB-60961E3F96A1}</ProjectGuid>
+    <WindowsTargetPlatformVersion>10.0</WindowsTargetPlatformVersion>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <UseDebugLibraries>true</UseDebugLibraries>
+    <PlatformToolset>v143</PlatformToolset>
+    <CharacterSet>MultiByte</CharacterSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <UseDebugLibraries>false</UseDebugLibraries>
+    <PlatformToolset>v143</PlatformToolset>
+    <WholeProgramOptimization>true</WholeProgramOptimization>
+    <CharacterSet>MultiByte</CharacterSet>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
+  <ImportGroup Label="PropertySheets">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+  </ImportGroup>
+  <Import Project="..\toml++.props" />
+  <ItemDefinitionGroup>
+    <Link>
+      <SubSystem>Console</SubSystem>
+    </Link>
+  </ItemDefinitionGroup>
+  <PropertyGroup>
+    <LocalDebuggerWorkingDirectory>..\examples</LocalDebuggerWorkingDirectory>
+  </PropertyGroup>
+  <ItemGroup>
+    <ClCompile Include="toml_merger.cpp" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="merge_overrides.toml" />
+    <None Include="merge_base.toml" />
+    <None Include="meson.build" />
+  </ItemGroup>
+  <ItemGroup>
+    <Natvis Include="..\toml++.natvis" />
+  </ItemGroup>
+  <ItemGroup>
+    <Text Include="CMakeLists.txt" />
+  </ItemGroup>
+  <ItemGroup>
+    <ClInclude Include="examples.h" />
+  </ItemGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
+</Project>

toml++.sln

@@ -91,6 +91,8 @@ Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "tt_encoder", "toml-test\tt_
 EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "odr_test", "tests\vs\odr_test.vcxproj", "{723FC4CA-0E24-4956-8FDC-E537EA3847AA}"
 EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "toml_merger", "examples\toml_merger.vcxproj", "{E467EB97-B066-4D38-B3DB-60961E3F96A1}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|x64 = Debug|x64
@@ -259,6 +261,10 @@ Global
 		{723FC4CA-0E24-4956-8FDC-E537EA3847AA}.Debug|x64.Build.0 = Debug|x64
 		{723FC4CA-0E24-4956-8FDC-E537EA3847AA}.Release|x64.ActiveCfg = Release|x64
 		{723FC4CA-0E24-4956-8FDC-E537EA3847AA}.Release|x64.Build.0 = Release|x64
+		{E467EB97-B066-4D38-B3DB-60961E3F96A1}.Debug|x64.ActiveCfg = Debug|x64
+		{E467EB97-B066-4D38-B3DB-60961E3F96A1}.Debug|x64.Build.0 = Debug|x64
+		{E467EB97-B066-4D38-B3DB-60961E3F96A1}.Release|x64.ActiveCfg = Release|x64
+		{E467EB97-B066-4D38-B3DB-60961E3F96A1}.Release|x64.Build.0 = Release|x64
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -304,6 +310,7 @@ Global
 		{8D19DE49-9687-4305-B59E-21F398415F5A} = {5DE43BF4-4EDD-4A7A-A422-764415BB3224}
 		{8F673261-5DFE-4B67-937A-61FC3F0082A2} = {5DE43BF4-4EDD-4A7A-A422-764415BB3224}
 		{723FC4CA-0E24-4956-8FDC-E537EA3847AA} = {4E25CF88-D7D8-4A9C-A52E-0D78281E82EC}
+		{E467EB97-B066-4D38-B3DB-60961E3F96A1} = {412816A5-9D22-4A30-BCDF-ABFB54BB3735}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {0926DDCC-88CD-4839-A82D-D9B99E02A0B1}