You can compile and evaluate DSP expressions directly in Apex:

• Compile a single expression:

pushtopics.Expression expr = pushtopics.Expression.compile('TO_UPPER_CASE(LastName)');
Object value = expr.evaluate(myContact);  
// Example: returns 'SMITH' if myContact.LastName = 'Smith'

• Compile a list of expressions:

pushtopics.Expression[] exprs = pushtopics.Expression.compile(
    new String[]{ 'TO_UPPER_CASE(LastName)', 'IS_BLANK(Email)' }
);

• Handle bulkification (for expressions with VLOOKUP or AGG functions):

pushtopics.Expression.setContextRecords(externalObjectList);
pushtopics.Expression expr = pushtopics.Expression.compile(
    'VLOOKUP("Account", "Parent.Type", "AccountExternalID__c", AccountExternalID__c)'
);
Object value = expr.evaluate(myExternalObject);
pushtopics.Expression.clearContextRecords();

Use setContextRecords and clearContextRecords when evaluating bulk expressions to ensure query optimization and bulkified execution.