Special symbols in actions

This table describes the complete set of special symbols you can use in actions within your grammar. These are translated by the codegen/action.g ANTLR v3 grammar (in filter mode). The rules mentioned below are found in action.g




x is enclosing rule, y is a return value, parameter, or predefined property. Rule ENCLOSING_RULE_SCOPE_ATTR.

r[int i] returns [int j]
  :    {$r.i, $r.j, $r.start, $r.stop, $r.st, $r.tree}


token scope attribute. Rule TOKEN_SCOPE_ATTR.




either a token label or token/rule list label like label+=expr. Rule LABEL_REF.


in a non-lexer grammar ISOLATED_TOKEN_REF


Yields a Token object created from that rule or fragment rule. Rule ISOLATED_LEXER_RULE_REF.


return value, parameter, predefined rule property, or token/rule
reference within enclosing rule's outermost alt.
y must be a "local" reference; i.e., it must be referring to
something defined within the enclosing rule. Rule LOCAL_ATTR.

r[int i] returns [int j]
  :    {$i, $j, $start, $stop, $st, $tree}


the only way to access the attributes within a dynamic scope
regardless of whether or not you are in the defining rule. Rule DYNAMIC_SCOPE_ATTR.

            scope Symbols { List names; }
            scope {int i;}
            scope Symbols;
                :    {$r::i=3;} s {$Symbols::names;}
            s    :    {$r::i; $Symbols::names;}


previous (just under top of stack). Rule DYNAMIC_NEGATIVE_INDEXED_SCOPE_ATTR.


top of stack - i where the '-' MUST BE PRESENT;
i.e., i cannot simply be negative without the '-' sign! Rule DYNAMIC_NEGATIVE_INDEXED_SCOPE_ATTR.


absolute index i (0..size-1). Rule DYNAMIC_NEGATIVE_INDEXED_SCOPE_ATTR.


is the absolute 0 indexed element (bottom of the stack). Rule DYNAMIC_NEGATIVE_INDEXED_SCOPE_ATTR.


returns the size of the current stack of the scope. Note: This particular syntax is target-dependent. Look at the target page for other targets than Java.


r is a rule's dynamic scope or a global shared scope.
Isolated $rulename is not allowed unless it has a dynamic scope and there is no reference to rulename in the enclosing alternative, which would be ambiguous. Rule ISOLATED_DYNAMIC_SCOPE.

The following symbols relate to StringTemplate templates.




Create instance of template foo, setting attribute arguments. Rule TEMPLATE_INSTANCE.


indirect template ctor reference. Rule INDIRECT_TEMPLATE_INSTANCE.

%x.y = z;

set template attribute y of x (always set never get attr)
to z [languages like python without ';' must still use the
';' which the code generator is free to remove during code gen]. Rule SET_ATTRIBUTE.

%{expr}.y = z;

template attribute y of StringTemplate-typed expr to z. Rule SET_EXPR_ATTRIBUTE.


anonymous template from string expr. Rule TEMPLATE_EXPR.