scala parse使用记录

1、

import ._

class ExprParser extends RegexParsers{
	val number="[0-9]+".r
	def expr:Parser[Any]=term ~ opt(("+" | "-") ~ expr)
	def term:Parser[Any]=factor ~ rep("*" ~ factor)
	def factor:Parser[Any]=number | "(" ~ expr ~ ")"
}

object Parser_ex extends App{
	val parser=new ExprParser
	val result=(,"3-4*5") //"3-4-5"会出错，后面例子有解决办法
	if() 
		println()
	val result2=(,"3-4/5") //从左解析，直到找不到可以解析的。解析不了"/"，会停下来。
	if() 
		println()
}

2、

import ._

class ExprParser extends RegexParsers{
	val number="[0-9]+".r
	def expr:Parser[Int]=term ~ opt(("+" | "-") ~ expr) ^^ {
		case t ~ None => t
		case t ~ Some("+" ~ e) => t+e
		case t ~ Some("-" ~ e) => t-e
	}
	def term:Parser[Int]=factor ~ rep("*" ~ factor) ^^ {
		case f ~ r => f*(_._2).product
	}
	def factor:Parser[Int]=number ^^ {_.toInt} | "(" ~ expr ~ ")" ^^ {
		case _ ~ e ~ _ => e
	}
}

object Parser_ex2 extends App{
	val parser=new ExprParser
	val result=(,"3-4*5") //"3-4-5"会出错，后面例子有解决办法
	if() 
		println()
	val result2=(,"3-4/5") //从左解析，直到找不到可以解析的。解析不了"/"，会停下来。
	if() 
		println()
}

3、

import ._

class ExprParser extends RegexParsers{
	val number="[0-9]+".r
	def expr:Parser[Int]=term ~ opt(("+" | "-") ~ expr) ^^ {
		case t ~ None => t
		case t ~ Some("+" ~ e) => t+e
		case t ~ Some("-" ~ e) => t-e
	}
	def term:Parser[Int]=factor ~ rep("*" ~> factor) ^^ {
		case f ~ r => f*
	}
	def factor:Parser[Int]=number ^^ {_.toInt} | "(" ~> expr <~ ")"
}

object Parser_ex3 extends App{
	val parser=new ExprParser
	val result=(,"3-4*5") //"3-4-5"会出错，后面例子有解决办法
	if() 
		println()
	val result2=(,"3-4/5") //从左解析，直到找不到可以解析的。解析不了"/"，会停下来。
	if() 
		println()
}

4、

import ._

class Expr
case class Number(value:Int) extends Expr
case class Operator(op:String,left:Expr,right:Expr) extends Expr

class ExprParser extends RegexParsers{
	val wholeNumber="[0-9]+".r
	def expr:Parser[Expr]=term ~ opt(("+" | "-") ~ expr) ^^ {
		case t ~ None => t
		case t ~ Some("+" ~ e) => Operator("+",t,e)
		case t ~ Some("-" ~ e) => Operator("-",t,e)
	}
	def term:Parser[Expr]=(factor ~ opt("*" ~> term)) ^^ {
		case a ~ None => a
		case a ~ Some(b) => Operator("*",a,b)
	}
	def factor:Parser[Expr]=wholeNumber ^^ (n => Number()) | "(" ~> expr <~ ")"
}

object Parser_ex4 extends App{
	val parser=new ExprParser
	val result=(,"3-4*5") //"3-4-5"会出错，后面例子有解决办法
	if() 
		println()
}

5、

import ._

class ExprParser extends RegexParsers{
	val number="[0-9]+".r
	def expr:Parser[Int]=term ~ rep(("+" | "-") ~ term ^^ {
			case "+" ~ t => t
			case "-" ~ t => -t
		}) ^^ {
		case t ~ r => t+
	}
	def term:Parser[Int]=factor ~ rep("*" ~> factor) ^^ {
		case f ~ r => f*
	}
	def factor:Parser[Int]=number ^^ {_.toInt} | "(" ~> expr <~ ")"
}

object Parser_ex5 extends App{
	val parser=new ExprParser
	val result=(,"3-4-5")
	if() 
		println()
}

6、

import ._
import ._

class ExprParser extends RegexParsers with PackratParsers {
	lazy val ones:PackratParser[Any]=ones ~ "1" ^^ {case a ~ b => a+b } | "1"

	def parseAll[T](p:Parser[T],input:String)=
		phrase(p)(new PackratReader(new CharSequenceReader(input)))

	val number="[0-9]+".r
	/*
	lazy val expr:PackratParser[Any]=opt(log(expr)("expr:") ~ ("+" | "-")) ~ term
	lazy val term:PackratParser[Any]=factor ~ rep("*" ~ factor)
	lazy val factor:PackratParser[Any]=number | "(" ~ expr ~ ")"
	*/
	//(Some(((Some(((None~(3~List()))~-))~(4~List()))~-))~(5~List())) //在不知道如何做的时候，参考parser_ex.scala打印出解析结果
	//opt(log(expr)("expr:") ~ ("+" | "-")) ~ term
	/*
	trying expr: at $PackratReader@16b83
	cc
	expr: --> [1.1] failure: Base Failure
	
	3-4-5
	^
	trying expr: at $PackratReader@16b83
	cc
	expr: --> [1.2] parsed: (None~(3~List()))
	trying expr: at $PackratReader@16b83
	cc
	expr: --> [1.4] parsed: (Some(((None~(3~List()))~-))~(4~List()))
	trying expr: at $PackratReader@16b83
	cc
	expr: --> [1.6] parsed: (Some(((Some(((None~(3~List()))~-))~(4~List()))~-))~(5~L
	ist()))
	(Some(((Some(((None~(3~List()))~-))~(4~List()))~-))~(5~List()))
	*/
	lazy val expr:PackratParser[Int]=opt(expr ~ ("+" | "-")) ~ term  ^^ {
		case (None ~ (r)) => r //记住这个吧：(3~List())是用(r)来匹配，并且r就表示3，试出来的。
		case (Some((e ~ "+")) ~ (r)) => e+r
		case (Some((e ~ "-")) ~ (r)) => e-r
	}
	lazy val term:PackratParser[Int]=factor ~ rep("*" ~> factor) ^^ {
		case f ~ r => f*
	}
	lazy val factor:PackratParser[Int]=number ^^ {_.toInt} | "(" ~> expr <~ ")"
}

object Parser_ex6 extends App{
	val parser=new ExprParser
	val result=(,"3-4-5")
	if() 
		println()
	val result2=(,"3-4*5")
	if() 
		println()
	val result3=(,"111111")
	if() 
		println()
}