how to get specified property

[zrwsmd]

demo.txt

IF var1 < 20 THEN
b := TRUE;
ELSE
b := FALSE;
END_IF;

this demo.txt is refered from others ,how can i get var1 property from Expression;

besides ,i am a little confused about this part

[msujew]

Hey @zrwsmd,

your Unary_expression and Primary_Expression parser rules should be refined a bit:

Power_expression infers Expression:
    Primary_Expression ({infer BinaryExpression.left=current} operator=('**')  right=Primary_Expression)*;

Unary_expression infers Expression:
   operator=('-' | 'NOT') value=Expression;

// primary_expression = constant | enumerated_value | variable | "(" expression ")" | function_name "(" param_assignment {"," param_assignment} ")";
Primary_Expression infers Expression:
Constant
| '(' Expression ')'
| FunctionExpression
| VariableExpression
| Unary_expression;

FunctionExpression infers Expression:
    {infer FunctionExpression} name=Function_name params=Invoke_subrule;

VariableExpression infers Expression:
    {infer VariableExpression} variable=Variable;

See here for the full grammar

besides ,i am a little confused about this part

What are you confused about?