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我想在ActionScript中使用ANTLR 网站上的简单表达式求值器示例,我已经能够使java 版本正常工作。但我的ActionScript版本中得到以下 错误:语法错误
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at org.antlr.runtime::Lexer/nextToken()[/Users/gscott/antlr/code/antlr/main/runtime/ActionScript/project/src/org/antlr/runtime/Lexer.as:69]
at org.antlr.runtime::CommonTokenStream/fillBuffer()[/Users/gscott/antlr/code/antlr/main/runtime/ActionScript/project/src/org/antlr/runtime/CommonTokenStream.as:84]
at org.antlr.runtime::CommonTokenStream/LT()[/Users/gscott/antlr/code/antlr/main/runtime/ActionScript/project/src/org/antlr/runtime/CommonTokenStream.as:227]
at org.antlr.runtime::CommonTokenStream/LA()[/Users/gscott/antlr/code/antlr/main/runtime/ActionScript/project/src/org/antlr/runtime/CommonTokenStream.as:289]
at Eval_in_ASParser/prog()[C:\Users\Wayne-VII\Documents\Flex Builder 3\ANTLR_AIR_01\src\Eval_in_ASParser.as:61]
at ANTLR_AIR_01/runProgram()[C:\Users\Wayne-VII\Documents\Flex Builder 3\ANTLR_AIR_01\src\ANTLR_AIR_01.mxml:11]
at ANTLR_AIR_01/__bRunSource_click()[C:\Users\Wayne-VII\Documents\Flex Builder 3\ANTLR_AIR_01\src\ANTLR_AIR_01.mxml:20]
好,因为代码是在SWC文件中,不能在调试器中看到的那样,我下载 的ActionScript源,并试图运行Ant构建,失败了。
所以,这里是我的ANTLR语法:
grammar Eval_in_AS;
options {
language=ActionScript;
}
@header {
//import java.util.HashMap;
import flash.utils.Dictionary;
}
@members {
/** Map variable name to Integer object holding value */
public var memory:Dictionary = new Dictionary();
public var output:String = new String();
public function getOutput():String
{
return output;
}
}
prog: stat+ EOF;
stat: expr NEWLINE {output +="\n" + $expr + ":" + $expr.value;}
| ID '=' expr NEWLINE
{memory[$ID.text] = int($expr.value);}
| NEWLINE
;
expr returns [int value]
: e=multExpr {$value = $e.value;}
( '+' e=multExpr {$value += $e.value;}
| '-' e=multExpr {$value -= $e.value;}
)*
;
multExpr returns [int value]
: e=atom {$value = $e.value;} ('*' e=atom {$value *= $e.value;})*
;
atom returns [int value]
: INT {$value = int($INT.text);}
| ID
{
if (memory.hasOwnProperty($ID.text)) {$value = memory[$ID.text];}
else {output +="\nundefined variable:"+$ID.text+"\n";$value = 0;}
}
| '(' expr ')' {$value = $expr.value;}
;
ID : ('a'..'z'|'A'..'Z')+ ;
INT : '0'..'9'+ ;
NEWLINE:'\r'? '\n' ;
WS : (' '|'\t')+ {skip();} ;
这里是我的试验台:
var lexer:Eval_in_ASLexer = new Eval_in_ASLexer(taSource.text as CharStream);
var tokens:CommonTokenStream = new CommonTokenStream(lexer);
var parser:Eval_in_ASParser = new Eval_in_ASParser(tokens);
parser.prog();
taOutput.text = parser.getOutput();
在上面的代码,taOutput是显示文本区域。我的意见是:
a=3
a
任何人都可以看到我在做什么错?
当然,我认为ANTLR的ActionScript目标版本存在一个错误,但我不喜欢其他人在他们的代码时责怪工具。所以首先我问我的编码是否有问题。
我认为问题是新版本的ANTLR 3.2.2和ANTLRWorks没有生成正确的代码。阅读其他需要使用命令行工具的地方。结束这个问题。 – WayneH 2010-10-23 15:54:00