Parse Nested Block Structure using ANTLR - antlr

Question

I have this program
{
run_and_branch(Test1)
then
{
}
else
{
}
{
run_and_branch(Test2)
then
{
}
else
{
run(Test3);
run(Test4);
run(Test5);
}
}
run_and_branch(Test6)
then
{
}
else
{
}
run(Test7);
{
run(Test8);
run(Test9);
run(Test_10);
}
}
Below is my ANLTR Grammar File
prog
: block EOF;
block
: START_BLOCK END_BLOCK -> BLOCK|
START_BLOCK block* END_BLOCK -> block*|
test=run_statement b=block* -> ^($test $b*)|
test2=run_branch_statement THEN pass=block ELSE fail=block -> ^($test2 ^(PASS $pass) ^(FAIL $fail))
;
run_branch_statement
: RUN_AND_BRANCH OPEN_BRACKET ID CLOSE_BRACKET -> ID;
run_statement
: RUN OPEN_BRACKET ID CLOSE_BRACKET SEMICOLON -> ID;
THEN : 'then';
ELSE : 'else';
RUN_AND_BRANCH : 'run_and_branch';
RUN : 'run';
START_BLOCK
: '{' ;
END_BLOCK
: '}' ;
OPEN_BRACKET
: '(';
CLOSE_BRACKET
: ')';
SEMICOLON
: ';'
;
ID : ('a'..'z'|'A'..'Z'|'_'|'0'..'9') (':'|'%'|'='|'\''|'a'..'z'|'A'..'Z'|'0'..'9'|'_'|'-'|'.'|'+'|'*'|'/'|'\\')*
;
WS : ( ' '
| '\t'
| '\r'
| '\n'
) {$channel=HIDDEN;}
;
Using ANTLWorks I get the following AST:
As you can see in the AST there is no link between the Test1 and Test2 as depedency. I want to have the AST show this information so that I can traverse the AST and get the Test depedency Structure
I am expecting the AST look something like this

Answer 1

ANTLR doesn't work this way. ANTLR produces a tree, not a graph, so there is no way to represent the desired output at the grammar level. In addition, if you tried to write tail-recursive rules to link control flow this way you would quickly run into stack overflow exceptions since ANTLR produces recursive-descent parsers.
You need to take the AST produced by ANTLR and perform separate control flow analysis on it to get a control flow graph.