Add a substring function to the formula language.

Also added a unit test for the function.

changelog

@@ -3,6 +3,8 @@ Version 1.9.3+svn:
    * Delfadors Memoirs:
      * Fixed bug #17273: Made difficulty selection conform to the style of all
        other mainline campaigns
+ * Formula language:
+   * Added substring function.
  * Graphics:
    * Terrain: added transitions for the wood floor.
  * Language and i18n:

src/CMakeLists.txt

@@ -794,6 +794,7 @@ if(ENABLE_TESTS)
 		tests/utils/play_scenario.cpp
 		tests/test_config_cache.cpp
 		tests/test_formula_ai.cpp
+		tests/test_formula_function.cpp
 		tests/test_lexical_cast.cpp
 		tests/test_network_worker.cpp
 		tests/test_team.cpp

src/Makefile.am

@@ -450,6 +450,7 @@ test_SOURCES =  \
 	tests/utils/play_scenario.cpp \
 	tests/test_config_cache.cpp \
 	tests/test_formula_ai.cpp \
+	tests/formula_function.cpp \
 	tests/test_lexical_cast.cpp \
 	tests/test_network_worker.cpp \
 	tests/test_team.cpp \

src/SConscript

@@ -516,6 +516,7 @@ libtest_utils = test_env.Library("test_utils", test_utils_sources)
 test_sources = Split("""
     tests/main.cpp
     tests/test_formula_ai.cpp
+    tests/test_formula_function.cpp
     tests/test_lexical_cast.cpp	
     tests/test_network_worker.cpp
     tests/test_team.cpp

src/formula_function.cpp

@@ -29,6 +29,8 @@ static lg::log_domain log_engine("engine");
 #define DBG_NG LOG_STREAM(debug, log_engine)
 static lg::log_domain log_scripting_formula("scripting/formula");
 #define LOG_SF LOG_STREAM(info, log_scripting_formula)
+#define WRN_SF LOG_STREAM(warn, log_scripting_formula)
+#define ERR_SF LOG_STREAM(err, log_scripting_formula)
 
 namespace game_logic {
 
@@ -369,6 +371,55 @@ private:
 	}
 };
 
+class substring_function
+	: public function_expression {
+public:
+	explicit substring_function(const args_list& args)
+	     : function_expression("substring", args, 2, 3)
+	{}
+
+	variant execute(const formula_callable& variables
+			, formula_debugger *fdb) const {
+
+		std::string result = args()[0]->evaluate(variables, fdb).as_string();
+
+		int offset = args()[1]->evaluate(variables, fdb).as_int();
+		if(offset < 0) {
+			offset += result.size();
+			if(offset < 0) {
+				WRN_SF << "[concatenate] Offset '"
+						<< args()[1]->evaluate(variables, fdb).as_int()
+						<< "' results in a negative start in string '"
+						<< result
+						<< "' and is reset at the beginning of the string.\n";
+
+				offset = 0;
+			}
+		} else {
+			if(static_cast<size_t>(offset) >= result.size()) {
+				WRN_SF << "[concatenate] Offset '" << offset
+						<< "' is larger as the size of '" << result
+						<< "' and results in an empty string.\n";
+
+				return variant(std::string());
+			}
+		}
+
+		if(args().size() > 2) {
+			const int size = args()[2]->evaluate(variables, fdb).as_int();
+			if(size < 0) {
+				ERR_SF << "[concatenate] Size is negative an "
+						<< "empty string is returned.\n";
+
+				return variant(std::string());
+			}
+			return variant(result.substr(offset, size));
+		} else {
+			return variant(result.substr(offset));
+		}
+	}
+};
+
 class index_of_function : public function_expression {
 public:
 	explicit index_of_function(const args_list& args)
@@ -1050,6 +1101,7 @@ functions_map& get_functions_map() {
 		FUNCTION(values);
 		FUNCTION(tolist);
 		FUNCTION(tomap);
+		FUNCTION(substring);
 #undef FUNCTION
 	}
 

src/tests/test_formula_function.cpp

@@ -0,0 +1,91 @@
+/* $Id$ */
+/*
+   Copyright (C) 2010 by Mark de Wever <koraq@xs4all.nl>
+   Part of the Battle for Wesnoth Project http://www.wesnoth.org/
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY.
+
+   See the COPYING file for more details.
+*/
+
+#define GETTEXT_DOMAIN "wesnoth-test"
+
+#include <boost/test/unit_test.hpp>
+
+#include "formula_function.hpp"
+
+BOOST_AUTO_TEST_SUITE(formula_function)
+
+BOOST_AUTO_TEST_CASE(test_formula_function_substring)
+{
+	BOOST_CHECK_EQUAL(
+			game_logic::formula("substring('hello world', 0)")
+				.evaluate().as_string()
+			, "hello world");
+
+	BOOST_CHECK_EQUAL(
+			game_logic::formula("substring('hello world', 6)")
+				.evaluate().as_string()
+			, "world");
+
+	BOOST_CHECK_EQUAL(
+			game_logic::formula("substring('hello world', 11)")
+				.evaluate().as_string()
+			, "");
+
+
+	BOOST_CHECK_EQUAL(
+			game_logic::formula("substring('hello world', -1)")
+				.evaluate().as_string()
+			, "d");
+
+	BOOST_CHECK_EQUAL(
+			game_logic::formula("substring('hello world', -5)")
+				.evaluate().as_string()
+			, "world");
+
+	BOOST_CHECK_EQUAL(
+			game_logic::formula("substring('hello world', -11)")
+				.evaluate().as_string()
+			, "hello world");
+
+	BOOST_CHECK_EQUAL(
+			game_logic::formula("substring('hello world', -12)")
+				.evaluate().as_string()
+			, "hello world");
+
+
+	BOOST_CHECK_EQUAL(
+			game_logic::formula("substring('hello world', 0, 0)")
+				.evaluate().as_string()
+			, "");
+
+	BOOST_CHECK_EQUAL(
+			game_logic::formula("substring('hello world', 0, -1)")
+				.evaluate().as_string()
+			, "");
+
+	BOOST_CHECK_EQUAL(
+			game_logic::formula("substring('hello world', 5, 1)")
+				.evaluate().as_string()
+			, " ");
+
+	BOOST_CHECK_EQUAL(
+			game_logic::formula("substring('hello world', 1, 9)")
+				.evaluate().as_string()
+			, "ello worl");
+
+	BOOST_CHECK_EQUAL(
+			game_logic::formula("substring('hello world', -10, 9)")
+				.evaluate().as_string()
+			, "ello worl");
+
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+