started to implement Function class which represents functions and methods, both on the host and the client side

git-svn-id: file:///var/local/svn/basicwriter@73 daaaf23c-2e50-4459-9457-1e69db5a47bf

1 files changed, 161 insertions, 0 deletions

diff --git a/src/core/script/Function.hpp b/src/core/script/Function.hpp
new file mode 100644
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+++ b/src/core/script/Function.hpp
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+/*
+    Ousía
+    Copyright (C) 2014, 2015  Benjamin Paaßen, Andreas Stöckel
+
+    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 3 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; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _OUSIA_FUNCTION_HPP_
+#define _OUSIA_FUNCTION_HPP_
+
+#include <exception>
+#include <utility>
+#include <vector>
+
+#include "Variant.hpp"
+
+namespace ousia {
+namespace script {
+
+/**
+ * The abstract Function class is most basic version of a function handle --
+ * just a virtual "call" function which calls the underlying code.
+ */
+class Function {
+
+public:
+
+	/**
+	 * Abstract function which is meant to call the underlying function (be it
+	 * a host or a script function) with the given arguments.
+	 *
+	 * @param args is a vector containing all arguments that shall be passed to
+	 * the function.
+	 * @return a Variant containing the return value.
+	 */
+	virtual Variant call(const std::vector<Variant> &args) const = 0;
+
+};
+
+/**
+ * The ArgumentDescriptor class is used to describe the type of a function
+ * argument.
+ */
+struct ArgumentDescriptor {
+
+	const VariantType type;
+	const bool hasDefault;
+	const Variant defaultValue;
+
+	ArgumentDescriptor(VariantType type) :
+		type(type), hasDefault(false) {};
+
+	ArgumentDescriptor(VariantType type, const Variant &defaultValue) :
+		type(type), hasDefault(true), defaultValue(defaultValue) {};
+
+};
+
+/**
+ * ArgumentValidatorError is an exception type used to represent argument
+ * validator errors.
+ */
+class ArgumentValidatorError : std::exception {
+
+public:
+
+	const int index;
+
+	const std::string msg;
+
+	ArgumentValidatorError(int index, const std::string &msg) :
+		index(index), msg(msg) {};
+
+	virtual const char* what() const noexcept override
+	{
+		return msg.c_str();
+	}
+
+};
+
+/**
+ * The ArgumentValidator class is responsible for checking whether the given
+ * arguments passed to a function match the description.
+ */
+class ArgumentValidator {
+
+private:
+	/**
+	 * List containing the argument descriptors.
+	 */
+	const std::vector<ArgumentDescriptor> descriptors;
+
+	/**
+	 * Argument index in the input array, at which the last error occured.
+	 */
+	int errorIndex = -1;
+
+	/**
+	 * Error message for the last validation error.
+	 */
+	std::string errorMessage;
+
+public:
+
+	/**
+	 * Constructor of the argument validator class.
+	 *
+	 * @param descriptors is a list of ArgumentDescriptors which should be used
+	 * for the validation.
+	 */
+	ArgumentValidator(const std::vector<ArgumentDescriptor> &descriptors) :
+		descriptors(descriptors) {}
+
+	/**
+	 * Validates and augments the given argument list (e.g. adds the default
+	 * values).
+	 *
+	 * @param args contains the input arguments.
+	 * @return a pair, where the first element specifies whether the arguments
+	 * were validated sucessfully and the second argument contains the augmented
+	 * list of arguments. If false is returned, use the error function to get
+	 * more information about the error.
+	 */
+	std::pair<bool, std::vector<Variant>> validate(const std::vector<Variant> &args);
+
+	/**
+	 * Returns an ArgumentValidatorError instance containing the argument index
+	 * in the input array, at which the error occured and an explaining error
+	 * message. As ArgumentValidatorError is derived from std::exception,
+	 * the result of this function is throwable.
+	 *
+	 * @return an ArgumentValidatorError instance containing information about
+	 * the last error. If no error occurred, the message will be empty and
+	 * the argument index will be set to -1.
+	 */
+	ArgumentValidatorError error()
+	{
+		return ArgumentValidatorError(errorIndex, errorMessage);
+	}
+
+};
+
+/**
+ * The HostFunction class represents a function that resides in the script host.
+ */
+
+}
+}
+
+#endif /* _OUSIA_FUNCTION_HPP_ */
+