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
| Syntax | Description |
|---|---|
| $enclosingRule.attr | x is enclosing rule, y is a return value, parameter, or predefined property. Rule ENCLOSING_RULE_SCOPE_ATTR.
r[int i] returns [int j]
: {$r.i, $r.j, $r.start, $r.stop, $r.st, $r.tree}
;
|
| $tokenLabel.prop $tokenRef.prop |
token scope attribute. Rule TOKEN_SCOPE_ATTR. |
| $rulelabel.attr $ruleref.attr |
Rule RULE_SCOPE_ATTR. |
| $label | either a token label or token/rule list label like label+=expr. Rule LABEL_REF. |
| $tokenref | in a non-lexer grammar ISOLATED_TOKEN_REF |
| $lexerruleref | Yields a Token object created from that rule or fragment rule. Rule ISOLATED_LEXER_RULE_REF. |
| $y | return value, parameter, predefined rule property, or token/rule reference within enclosing rule's outermost alt. y must be a "local" reference; i.e., it must be referring to something defined within the enclosing rule. Rule LOCAL_ATTR. r[int i] returns [int j]
: {$i, $j, $start, $stop, $st, $tree}
;
|
| $x::y | the only way to access the attributes within a dynamic scope regardless of whether or not you are in the defining rule. Rule DYNAMIC_SCOPE_ATTR. scope Symbols { List names; }
r
scope {int i;}
scope Symbols;
: {$r::i=3;} s {$Symbols::names;}
;
s : {$r::i; $Symbols::names;}
;
|
| $x[-1]::y | previous (just under top of stack). Rule DYNAMIC_NEGATIVE_INDEXED_SCOPE_ATTR. |
| $x[-i]::y | 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. |
| $x[i]::y | absolute index i (0..size-1). Rule DYNAMIC_NEGATIVE_INDEXED_SCOPE_ATTR. |
| $x[0]::y | is the absolute 0 indexed element (bottom of the stack). Rule DYNAMIC_NEGATIVE_INDEXED_SCOPE_ATTR. |
| $x.size() | 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 | 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.
| Syntax | 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. |