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AST operators

Code gen templates for operators; assume root=null, kids=List<Token>

grammar fragment

code

A 

kids.add($A);
_localctx.tree = adaptor.create(root, kids); // A

A B 

kids.add($A);
kids.add($B);
_localctx.tree = adaptor.create(root, kids); // ^(nil A B)

A^ B 

root = root==null ? $A : adaptor.becomeRoot(root, $A, kids);
kids.add($ID);
_localctx.tree = adaptor.create(root, kids); // ^(A B)

A B^ 

kids.add($A);
root = root==null ? $B : adaptor.becomeRoot(root, $B, kids);
_localctx.tree = adaptor.create(root, kids); // ^(B A)

A B^ C 

kids.add($A);
root = root==null ? $B : adaptor.becomeRoot(root, $B, kids);
kids.add($C);
_localctx.tree = adaptor.create(root, kids); // ^(B A C)

A B^ C^ D 

kids.add($A);
root = root==null ? $B : adaptor.becomeRoot(root, $B, kids);
root = root==null ? $C : adaptor.becomeRoot(root, $C, kids);
kids.add($D);
_localctx.tree = adaptor.create(root, kids); // ^(C ^(B A) D)

Rewrites

Code gen templates for rewrite rules; assume root=adaptor.nil(), kids is List<Tree>. assume we can't distinguish statically single vs multi-valued elements from left of -> for now.

grammar fragment

code

A -> A 

A_it = A_list.iterator();
kids.add(adaptor.create(A_it.next()));
_localctx.tree = adaptor.create(root, kids); // A

A -> A A 

A_it = A_list.iterator();
kids.add(adaptor.create(A_it.next()));
kids.add(adaptor.create(A_it.next())); // iterator keeps returning A nodes
_localctx.tree = adaptor.create(root, kids); // ^(nil A A)

A B -> ^(A B) 

A_it = A_list.iterator();
B_it = B_list.iterator();
root = adaptor.create(A_it.next());
kids.add(adaptor.create(B_it.next()));
_localctx.tree = adaptor.create(root, kids); // ^(nil A A)

A+ -> A* 

A_it = A_list.iterator();
while (A_it.hasNext()) {
    kids.add(adaptor.create(A_it.next()));
}
_localctx.tree = adaptor.create(root, kids); // ^(nil A A ... A)

A+ -> ^(B A*) 

A_it = A_list.iterator();
B_it = B_list.iterator();
root = adaptor.create(B_it.next());
while (A_it.hasNext()) {
    kids.add(adaptor.create(A_it.next()));
}
_localctx.tree = adaptor.create(root, kids); // ^(B A A ... A)

A+ -> ^(B A)* 

A_it = A_list.iterator();
B_it = B_list.iterator();
root_1 = null;
while (A_it.hasNext()) {
    root_1 = adaptor.create(B_it.next());
    kids.add(adaptor.create(A_it.next()));
    kids.add( adaptor.create(root_1, kids) ); // ^(B A)
}
_localctx.tree = adaptor.create(root, kids); // ^(nil ^(B A) ^(B A) ...)
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