decl : type ID {System.out.println($ID.text);}';';
type : 'int' | 'float';

decl : type ID ';' {System.out.println("var " + $ID.text+":"+$type.text+";");}
        | t=ID id=ID ';' {System.out.println("var " + $id.text+":"+$t.text+";");};

decl : type ids+=ID (',' ids+=ID)* ';'; //ids是ID token的List

decl : type declarator[$type.text] ';' ;//使用规则参数
declarator[String typeText]
    : '*' ID {"var " + $ID.text+":^"+$typeText+";")}
       | ID {System.out.println("var " + $ID.text+":"+$typeText+";")};

field : d=decl ';'
{System.out.println("type=)+$d.type+", vars="+$d.vars);};//使用规则返回值
decl returns[String type, List vars]
: t=type ids+=ID (',' ids+=ID)* {$type=$t.text;$vars=ids;}

@members{String methodName;}//文法内全局作用域变量
method : type ID {methodName=$ID.text;} body ;
body : '{' statement+ '}' ;
statement : decl {...methodName...} ';'//引用变量
| ... ;

method scope {String name;}//规则作用域变量
: type ID {$method::name=$ID.text;} body ;
body : '{' statement+ '}' ;
statement : decl {...$method::name...} ';'//引用变量
| ... ;

parser grammar T;
@header{package p;}
@members{
int i;
public TParser(TokenStream input, int foo){
this(input);
i = foo;
} 

}
a[int x] returns [int y]
@init {int z=0;}
@after {System.out.println("after matching rule, before finally");}
: {<<action1>>} A {<<action2>>}
;
catch[RecognitionException re] {
System.err.println("error");
}
finally {<<do-this-no-matter-what-happened>>}

lexer grammar T;
R : a='c' b='hin' c=. {$a, $b.text, $c};// a,c都不是token，b是token

void foo(){int x=0; bar();}
void bar(){int y=x;}

grammar T;

@members{
int level = 0;
boolean isDefined(String variable){
boolean result = false;
    //注：不要将中文注释放到文法定义文件中，至少在我的环境中是这样
    //这里索引i从level-1的原因是：代码块(block)层次从1计数，而block对应的Stack从0计数
for(int i=level-1; i>=0; i--){
if($block[i]::symbols.contains(variable)){
System.out.println(variable + " found in nesting level " + (i+1));
result = true;
}
}
return result;
}
}

prog : block;

block
scope{
List symbols;
}
@init{
$block::symbols = new ArrayList();
level++;
}
@after{
System.out.println("symbols level " + level + " = " + $block::symbols);
level--;
}
: '{'decl* stat+'}'
;

decl : 'int' ID {$block::symbols.add($ID.text);}';'
;

stat : ID '=' INT ';'
{

System.err.println("undefined variable level  " + level + ": "+ $ID.text);
}
}
| block
;

ID  : ('a'..'z'|'A'..'Z'|'_') ('a'..'z'|'A'..'Z'|'0'..'9'|'_')*;
INT : '0'..'9'+;
WS  :   ( ' '| '\t'| '\r'| '\n') {$channel=HIDDEN;};

{
int i;
int j;
i = 0;
{
int i;
int x;
x = 5;
}
x = 3;
}

grammar T;
scope CScope{
String name;
List symbols;
}

@members{
  boolean isDefined(String variable){
        boolean result = false;
          for(int i=$CScope.size()-1; i>=0; i--){
                if($CScope[i]::symbols.contains(variable)){
                          System.out.println(">" + variable + " found in " +$CScope[i]::name);
                          result = true;
                  }
          }
          return result;
}
 }

prog scope CScope;
@init {
$CScope::symbols = new ArrayList();
$CScope::name = "global";
}
@after {
System.out.println("global symbols = " + $CScope::symbols);
}
: decl* func*;
func scope CScope;
@init {
$CScope::symbols = new ArrayList();
}
@after {
System.out.println("function " + $CScope::name + "()'s symbols = " +$CScope::symbols);
}
: 'void' ID{$CScope::name=$ID.text;} '(' ')' '{' decl* stat+ '}'
;
block scope CScope;
@init {
$CScope::symbols = new ArrayList();
$CScope::name = "level " + $CScope.size();
}
@after{
System.out.println("code block level " + $CScope.size() + " symbols = " +$CScope::symbols);
}
: '{'decl* stat+'}'
;
//注：不要将中文注释放到文法定义文件中，至少在我的环境中是这样
//查看生成的代码，decl()中调用了Stack#peek()，
//即，会使用动态作用域Stack中当前的作用域，最终还是使用block(引用该decl)的作用域
decl : 'int' ID {$CScope::symbols.add($ID.text);}';'
;
stat : ID '=' INT ';'
{
if(!isDefined($ID.text)){
System.err.println("undefined variable in  " + $CScope::name + ": "+ $ID.text);
}
}
| block
;

ID  : ('a'..'z'|'A'..'Z'|'_') ('a'..'z'|'A'..'Z'|'0'..'9'|'_')*;
INT : '0'..'9'+;
WS  :   ( ' '| '\t'| '\r'| '\n') {$channel=HIDDEN;};

int i;
void f() {
     int i;
     {
int i;
i = 2;
     }
     i = 1;
}
void g(){
     i = 0;
     x = 3;
}