scala解析器。日志解析器实用程序的输出

我正在使用log解析器实用程序来跟踪解析。scala解析器。日志解析器实用程序的输出

Scala代码：

import scala.util.parsing.combinator.JavaTokenParsers 
object Arith extends JavaTokenParsers with App { 
    def expr: Parser[Any] = log(term~rep("+"~term | "-"~term))("expr") 
    def term: Parser[Any] = factor~rep("*"~factor | "/"~factor) 
    def factor: Parser[Any] = floatingPointNumber | "("~expr~")" 
    println(parseAll(expr, "2 * (3 + 7)")) 
}

输出：

trying expr at [email protected] 
trying expr at [email protected] 
expr --> [1.11] parsed: ((3~List())~List((+~(7~List())))) 
expr --> [1.12] parsed: ((2~List((*~(((~((3~List())~List((+~(7~List())))))~)))))~List()) 
[1.12] parsed: ((2~List((*~(((~((3~List())~List((+~(7~List())))))~)))))~List())

输入打印为[email protected]。有没有办法打印输入的字符串表示形式，如“2 *（3 + 7）”？

来源

2013-06-19 dips

覆盖log解决了我的问题。

Scala的段：

import scala.util.parsing.combinator.JavaTokenParsers 
object Arith extends JavaTokenParsers with App { 
    override def log[T](p: => Parser[T])(name: String): Parser[T] = Parser { in => 
     def prt(x: Input) = x.source.toString.drop(x.offset) 

     println("trying " + name + " at " + prt(in)) 
     val r = p(in) 
     println(name + " --> " + r + " next: " + prt(r.next)) 
     r 
    } 
    def expr: Parser[Any] = log(term ~ rep("+" ~ term | "-" ~ term))("expr") 
    def term: Parser[Any] = factor ~ rep("*" ~ factor | "/" ~ factor) 
    def factor: Parser[Any] = floatingPointNumber | "(" ~ expr ~ ")" 
    println(parseAll(expr, "(3+7)*2")) 
}

输出：

trying expr at (3+7)*2 
trying expr at 3+7)*2 
expr --> [1.5] parsed: ((3~List())~List((+~(7~List())))) next:)*2 
expr --> [1.8] parsed: (((((~((3~List())~List((+~(7~List())))))~))~List((*~2)))~List()) next: 
[1.8] parsed: (((((~((3~List())~List((+~(7~List())))))~))~List((*~2)))~List())

来源

2013-06-19 06:08:10 dips

scala解析器。日志解析器实用程序的输出

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