Add a command-line interface to the WML diff functionalityNote that this is only useful for WML documents that do not require preprocessing.

doc/man/wesnoth.6

@@ -104,6 +104,11 @@ information about command mode).
 .B --debug-lua
 enables some Lua debugging mechanisms
 .TP
+.BI -D,--diff \ left-file \  right-file
+diffs the two WML files; does not preprocess them first (to do that, run them through
+.B -p
+first). Outputs the diff as DiffWML on standard output.
+.TP
 .BI -e[ file ],\ --editor[ =file ]
 start the in-game map editor directly. If
 .I file
@@ -239,6 +244,10 @@ which defines a Wesnoth plugin. Similar to
 .BR --script ,
 but Lua file should return a function which will be run as a coroutine and periodically woken up with updates.
 .TP
+.BI -P,--patch \ base-file \  patch-file
+applies a DiffWML patch to a WML file; does not preprocess either of the files.
+Outputs the patched WML to standard output.
+.TP
 .BI -p,\ --preprocess \ source-file/folder \  target-directory
 preprocesses a specified file/folder. For each file(s) a plain .cfg file and a processed .cfg
 file will be written in specified target directory. If a folder is specified, it will

src/commandline_options.cpp

@@ -144,6 +144,10 @@ commandline_options::commandline_options (const std::vector<std::string>& args)
 	validate_schema(),
 	validate_wml(),
 	validate_with(),
+	do_diff(),
+	do_patch(),
+	diff_left(),
+	diff_right(),
 	version(false),
 	report(false),
 	windowed(false),
@@ -282,6 +286,8 @@ commandline_options::commandline_options (const std::vector<std::string>& args)
 		("validate-addon", po::value<std::string>(), "validate the specified addon's WML against the schema")
 		("validate-core", "validate the core WML against the schema")
 		("validate-schema", po::value<std::string>(), "validate a specified WML schema")
+		("diff,D", po::value<two_strings>()->multitoken(), "diff two preprocessed WML documents")
+		("patch,P", po::value<two_strings>()->multitoken(), "apply a patch to a preprocessed WML document")
 		;
 
 	po::options_description preprocessor_opts("Preprocessor mode options");
@@ -429,6 +435,18 @@ commandline_options::commandline_options (const std::vector<std::string>& args)
 		preprocess_path = vm["preprocess"].as<two_strings>().first;
 		preprocess_target = vm["preprocess"].as<two_strings>().second;
 	}
+	if (vm.count("diff"))
+	{
+		do_diff = true;
+		diff_left = vm["diff"].as<two_strings>().first;
+		diff_right = vm["diff"].as<two_strings>().second;
+	}
+	if (vm.count("patch"))
+	{
+		do_patch = true;
+		diff_left = vm["patch"].as<two_strings>().first;
+		diff_right = vm["patch"].as<two_strings>().second;
+	}
 	if (vm.count("preprocess-defines"))
 		preprocess_defines = utils::split(vm["preprocess-defines"].as<std::string>(), ',');
 	if (vm.count("preprocess-input-macros"))

src/commandline_options.hpp

@@ -215,6 +215,9 @@ public:
 	boost::optional<std::string> validate_wml;
 	/// Non-empty if --use-schema was given on the command line. Specifies the schema for use with --validate.
 	boost::optional<std::string> validate_with;
+	bool do_diff, do_patch;
+	/// Files for diffing or patching
+	std::string diff_left, diff_right;
 	/// True if --version was given on the command line. Prints version and exits.
 	bool version;
 	/// True if --report was given on the command line. Prints a bug report-style info dump and exits.

src/wesnoth.cpp

@@ -503,6 +503,29 @@ static int process_command_args(const commandline_options& cmdline_opts)
 		validator.set_create_exceptions(false); // Don't crash if there's an error, just go ahead anyway
 		return handle_validate_command(*cmdline_opts.validate_schema, validator, {});
 	}
+	
+	if(cmdline_opts.do_diff) {
+		config left, right;
+		std::ifstream in_left(cmdline_opts.diff_left);
+		std::ifstream in_right(cmdline_opts.diff_right);
+		read(left, in_left);
+		read(right, in_right);
+		config_writer out(std::cout, compression::format::NONE);
+		out.write(right.get_diff(left));
+		return 0;
+	}
+	
+	if(cmdline_opts.do_patch) {
+		config base, diff;
+		std::ifstream in_base(cmdline_opts.diff_left);
+		std::ifstream in_diff(cmdline_opts.diff_right);
+		read(base, in_base);
+		read(diff, in_diff);
+		base.apply_diff(diff);
+		config_writer out(std::cout, compression::format::NONE);
+		out.write(base);
+		return 0;
+	}
 
 	// Options changing their behavior dependent on some others should be checked below.
 
@@ -1036,6 +1059,8 @@ int main(int argc, char** argv)
 		   args[k] == "-R" ||
 		   args[k] == "--screenshot" ||
 		   args[k] == "--data-path" ||
+		   args[k] == "--diff" ||
+		   args[k] == "--patch" ||
 		   args[k] == "--userdata-path" ||
 		   args[k] == "--userconfig-path" ||
 		   args[k].compare(0, 11, "--validate=") == 0  ||