Java 扩展简单ANTLR语法以支持输入变量
我还在继续,现在我知道没有了。所以我自己用ANTLR3写了一个 我发现了一个非常好的例子: Exp.g:Java 扩展简单ANTLR语法以支持输入变量,java,antlr,antlr3,Java,Antlr,Antlr3,我还在继续,现在我知道没有了。所以我自己用ANTLR3写了一个 我发现了一个非常好的例子: Exp.g: grammar Exp; eval returns [double value] : exp=additionExp {$value = $exp.value;} ; additionExp returns [double value] : m1=multiplyExp {$value = $m1.value;} (
grammar Exp;
eval returns [double value]
: exp=additionExp {$value = $exp.value;}
;
additionExp returns [double value]
: m1=multiplyExp {$value = $m1.value;}
( '+' m2=multiplyExp {$value += $m2.value;}
| '-' m2=multiplyExp {$value -= $m2.value;}
)*
;
multiplyExp returns [double value]
: a1=atomExp {$value = $a1.value;}
( '*' a2=atomExp {$value *= $a2.value;}
| '/' a2=atomExp {$value /= $a2.value;}
)*
;
atomExp returns [double value]
: n=Number {$value = Double.parseDouble($n.text);}
| '(' exp=additionExp ')' {$value = $exp.value;}
;
Number
: ('0'..'9')+ ('.' ('0'..'9')+)?
;
WS
: (' ' | '\t' | '\r'| '\n') {$channel=HIDDEN;}
;
public Double evaluate(String string, Map<String, Double> input) throws RecognitionException {
ANTLRStringStream in = new ANTLRStringStream(string);
ExpLexer lexer = new ExpLexer(in);
CommonTokenStream tokens = new CommonTokenStream(lexer);
return new ExpParser(tokens).eval();
}
Java代码:
grammar Exp;
eval returns [double value]
: exp=additionExp {$value = $exp.value;}
;
additionExp returns [double value]
: m1=multiplyExp {$value = $m1.value;}
( '+' m2=multiplyExp {$value += $m2.value;}
| '-' m2=multiplyExp {$value -= $m2.value;}
)*
;
multiplyExp returns [double value]
: a1=atomExp {$value = $a1.value;}
( '*' a2=atomExp {$value *= $a2.value;}
| '/' a2=atomExp {$value /= $a2.value;}
)*
;
atomExp returns [double value]
: n=Number {$value = Double.parseDouble($n.text);}
| '(' exp=additionExp ')' {$value = $exp.value;}
;
Number
: ('0'..'9')+ ('.' ('0'..'9')+)?
;
WS
: (' ' | '\t' | '\r'| '\n') {$channel=HIDDEN;}
;
public Double evaluate(String string, Map<String, Double> input) throws RecognitionException {
ANTLRStringStream in = new ANTLRStringStream(string);
ExpLexer lexer = new ExpLexer(in);
CommonTokenStream tokens = new CommonTokenStream(lexer);
return new ExpParser(tokens).eval();
}
结果得到13分
现在,我的用例缺少的唯一一件事就是向其中注入简单的双变量,这样我就可以通过提供{“a”:12.0,“B”:14.0}作为输入映射来评估以下内容:
(A+B)/2
有什么想法吗?您可以在解析器中创建
映射内存
,并在语法中引入标识符
:
Identifier
: ('a'..'z' | 'A'..'Z' | '_') ('a'..'z' | 'A'..'Z' | '_' | '0'..'9')*
;
然后,您的atomExp
解析器规则如下所示:
atomExp returns [double value]
: n=Number {$value = Double.parseDouble($n.text);}
| i=Identifier {$value = memory.get($i.text);} // <- added!
| '(' exp=additionExp ')' {$value = $exp.value;}
;
祝你好运 呸,我花了时间来实现这一点,所以不妨发布它,尽管我被打败了:) 在下面的语法中,我实现了您希望执行的变量赋值格式
grammar Exp;
eval returns [double value]
scope
{
java.util.Hashtable varMap;
}
@init
{
$eval::varMap = new java.util.Hashtable();
}
: exp=additionExp {$value = $exp.value;}
| varList
;
additionExp returns [double value]
: m1=multiplyExp {$value = $m1.value;}
( '+' m2=multiplyExp {$value += $m2.value;}
| '-' m2=multiplyExp {$value -= $m2.value;}
)*
;
multiplyExp returns [double value]
: a1=atomExp {$value = $a1.value;}
( '*' a2=atomExp {$value *= $a2.value;}
| '/' a2=atomExp {$value /= $a2.value;}
)*
;
atomExp returns [double value]
: n=Number {$value = Double.parseDouble($n.text);}
| v=ID {$value = $eval::varMap.get($v);}
| '(' exp=additionExp ')' {$value = $exp.value;}
;
varList
:
OPEN_BRACE assignVar (COMMA assignVar)+ CLOSE_BRACE
;
assignVar
:QUOTE var=ID n=Number QUOTE COLON { $eval::varMap.put($var, $n); }
;
Number
: ('0'..'9')+ ('.' ('0'..'9')+)?
;
WS
: (' ' | '\t' | '\r'| '\n') {$channel=HIDDEN;}
;
fragment LETTER: LOWER | UPPER;
fragment LOWER: 'a'..'z';
fragment UPPER: 'A'..'Z';
OPEN_BRACE
: '{'
;
CLOSE_BRACE
: '}'
;
COLON : ';';
COMMA : ',';
QUOTE : '"';
ID
: LETTER*;
很抱歉,达里安:)。嗯,我首先写了arturh张贴的语法,所以我有点领先+然而,我还是拒绝了!不用担心,这是促成这样做的一部分风险:)
6.283185307179586
grammar Exp;
eval returns [double value]
scope
{
java.util.Hashtable varMap;
}
@init
{
$eval::varMap = new java.util.Hashtable();
}
: exp=additionExp {$value = $exp.value;}
| varList
;
additionExp returns [double value]
: m1=multiplyExp {$value = $m1.value;}
( '+' m2=multiplyExp {$value += $m2.value;}
| '-' m2=multiplyExp {$value -= $m2.value;}
)*
;
multiplyExp returns [double value]
: a1=atomExp {$value = $a1.value;}
( '*' a2=atomExp {$value *= $a2.value;}
| '/' a2=atomExp {$value /= $a2.value;}
)*
;
atomExp returns [double value]
: n=Number {$value = Double.parseDouble($n.text);}
| v=ID {$value = $eval::varMap.get($v);}
| '(' exp=additionExp ')' {$value = $exp.value;}
;
varList
:
OPEN_BRACE assignVar (COMMA assignVar)+ CLOSE_BRACE
;
assignVar
:QUOTE var=ID n=Number QUOTE COLON { $eval::varMap.put($var, $n); }
;
Number
: ('0'..'9')+ ('.' ('0'..'9')+)?
;
WS
: (' ' | '\t' | '\r'| '\n') {$channel=HIDDEN;}
;
fragment LETTER: LOWER | UPPER;
fragment LOWER: 'a'..'z';
fragment UPPER: 'A'..'Z';
OPEN_BRACE
: '{'
;
CLOSE_BRACE
: '}'
;
COLON : ';';
COMMA : ',';
QUOTE : '"';
ID
: LETTER*;