Wanna to add some business rule in the system when saving data. Don't want to hard code those rules.
Rules like "[field1] > 0 and [field2] < 10 or [field3] like 'CN%'" could be added to a configuration table and be checked when data saving.
So need to intepret these rules like "[field1] > 0 and [field2] < 10 or [field3] like 'CN%'" in the program.
It's like a basic AST(Abstract Syntax Tree) problem. Got real inspiration from https://github.com/DoctorWkt/acwj.
Begin writting an boolean_checker in C#.
Should support：
1.computing operator + and - and * and /
2.logic operators like 'AND' and 'OR' and 'LIKE' and '==' and '!=' and '>' and '<' and '>=' and '<='
3.Parentheses '(' and ')'
4.Able to check the rule is syntax correct.
5.Support inline function: substr(str, istart, ilen) and substr(str, istart)
6.replace [field] with real value by a json input, do boolean check and return TRUE or FALSE
Usage(see the sample in MainWindow): Initialize the scanner with the rule text Scanner scanner = new Scanner(rule_text);
1.check the rule is syntax correct for save, exception should raised if syntax error scanner.checkRule();
2.check the rule with actual value to get TURE or FALSE scanner.validateRule(json_str);