Validation

Validation in Gorgon UI is done over validator classes.

These classes should have the following members:

• Type: a type declaration of the type that is managed.
• bool IsValid(std::string): returns true if the given string is a valid value for the type
• bool AllowInsert(std::string start, std::string insert, std::string end): this function is used when typing or pasting into the editor. If the insert is a valid string to place between start and end this function should return true. The result of this function is not IsValid(start + insert + end) as in this case, a partially correct data should be allowed. Otherwise, it might be impossible to enter input. For instance, for Geometry::Point, entering 5 when the inputbox is empty should be allowed, even though 5 is not a valid point.
• bool AllowErase(std::string before, int count, std::string after): this function is used check if it is possible to erase count characters from before. The text after the deletion point is given in after. Having strong rules could cause difficulty in editing the data, thus extensive use of this function is not recommended.
• Type From(std::string text): Converts the given text in to type. This function should not throw even if the input is not valid. In this case it should return initial value for the Type.
• std::string ToString(const Type &value): Converts the given value into a string. Input validation requires a proper serialization as input systems may call ToString(From(text)) to fix the text. It is advisable to have unit tests ensuring correct serialization.