我發現了一個簡單的語法來開始學習ANTLR。我把它放在myGrammar.g文件中。這裏是語法:詞法分析動作中不允許使用屬性引用
grammar myGrammar;
/* This will be the entry point of our parser. */
eval
: additionExp
;
/* Addition and subtraction have the lowest precedence. */
additionExp
: multiplyExp
('+' multiplyExp
| '-' multiplyExp
)*
;
/* Multiplication and division have a higher precedence. */
multiplyExp
: atomExp
('*' atomExp
| '/' atomExp
)*
;
atomExp
: Number
| '(' additionExp ')'
;
/* A number: can be an integer value, or a decimal value */
Number
: ('0'..'9')+ ('.' ('0'..'9')+)?
;
/* We're going to ignore all white space characters */
WS
: (' ' | '\t' | '\r'| '\n') {$channel=HIDDEN;}
;
當我使用這個命令:
java -jar /usr/local/...(antlr path) /home/ali/Destop/...(myGrammar.g path)
我有這樣的錯誤:
myGrammar.g:39:36: attribute references not allowed in lexer actions: $channel
是什麼問題,我該怎麼辦?