Special symbols in actions

Description

$enclosingRule.attr

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

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

$tokenLabel.prop
$tokenRef.prop

token scope attribute

$rulelabel.attr
$ruleref.attr

RULE_SCOPE_ATTR

$label

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

$tokenref

in a non-lexer grammar ISOLATED_TOKEN_REF

$lexerruleref

ISOLATED_LEXER_RULE_REF from lexer

$y

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.

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

$x::y

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

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

ff

DYNAMIC_NEGATIVE_INDEXED_SCOPE_ATTR

$x[-1]::y

previous (just under top of stack)

$x[-i]::y

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

$x[i]::y

absolute index i (0..size-1)

$x[0]::y

is the absolute 0 indexed element (bottom of the stack)

$r

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

Description

%foo(a={},b={},...)

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

%({name-expr})(a={},...)

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.

%{string-expr}

anonymous template from string expr. Rule TEMPLATE_EXPR.