java - Finding duplicate expressions/parameters -

i have structure below

parameter -> condition -> rule

let need create business rule, customer age > 18

i have 2 parameters, customer age (p1) , 18(p2), p1 field parameter (ognl) , p2 constant parameter value 18.

so condition , customer age > 18 , rule.

problem statement : avoid user creating duplicate parameter/condition , rules.

solution : constant parameters, field parameters etc can check in db , compare if present.

now condition me,

customer age > 18 , 18 < customer age same in business terms.

the above cases can more complex.

(a + b) * (c + d) same (b + a) * (d + c) 

i need validate above expressions.

first approach - load expression db (can 10000's) , compare using stack/tree structure, kill objective.

second approach - thinking of building power full, let hashcode generator or can 1 int value against every expression (considering operators/brackets also). value should generated in such way validates above expression.

means a + b , b + a should generate same int value, , a - b , b - a should generate different.

maybe simplified version of first approach: filtering relevant expressions looking similar content insert database?

if know insert customer age can find expressions containing parameter , build stack/tree based on reduced set of expressions.