Scala Combinators JavaTokennParsers'||'；预期但'&燃气轮机'；建立

当我运行此测试时：

import com.dvMENTALmadness.parsers.{BinaryOp, ExprType, Number, SimpleEquationParser}
import org.scalatest.FlatSpec

class SimpleEquationParserTest extends FlatSpec {
  "(1+2) > (3+4)" should " == false" in {
    val result = SimpleEquationParser("(1+2) > (3+4)")
    println(result)
    assert( result == Right(BinaryOp(">",BinaryOp("+",Number(1.0),Number(2.0),ExprType.Num),BinaryOp("+",Number(3.0),Number(4.0),ExprType.Num),ExprType.Bool)) )
  }
}

我得到：

Left("`||' expected but `>' found") did not equal Right(BinaryOp(>,BinaryOp(+,Number(1.0),Number(2.0),Num),BinaryOp(+,Number(3.0),Number(4.0),Num),Bool))

如果我将表达式更改为

（（1+2）>（3+4））

它可以工作，但我需要能够支持可选的括号。有什么建议吗？下面是类定义以及日志跟踪：

package com.dvMENTALmadness.parsers

import com.dvMENTALmadness.parsers.ExprType.ExprType
import scala.util.parsing.combinator.{JavaTokenParsers, PackratParsers}

sealed trait Expr
sealed trait Var extends Expr {
  def key: String
}
object ExprType extends Enumeration {
  type ExprType = Value
  val Var, Num, Text, Bool = Value
}

case class Text(value: String) extends Expr
case class Number(value: Double) extends Expr
case class Bool(value: Boolean) extends Expr
case class NumericVar(key: String) extends Var
case class TextVar(key: String) extends Var
case class BoolVar(key: String) extends Var
case class AnyVar(key: String) extends Var
case class UnaryOp(operator: String, arg: Expr, expType: ExprType) extends Expr
case class BinaryOp(operator: String, left : Expr, right: Expr, expType: ExprType)  extends Expr

trait ExprParser extends JavaTokenParsers with PackratParsers {

  def foldExpr(etype: ExprType)(pat: Expr ~ List[String ~ Expr]) : Expr = pat match {
    case left ~ xs => xs.foldLeft(left)((left, acc) => acc match {
      case op ~ right => BinaryOp(op, left, right, etype)
    })
  }

  // see: http://jim-mcbeath.blogspot.com/2011/07/debugging-scala-parser-combinators.html
  implicit def toLogged(name: String) = new {
    def !!![T](p:Parser[T]) = log(p)(name) // for debugging
    //def !!![T](p:Parser[T]) = p         // for production
  }
}

trait BoolParser extends ExprParser {

  // Operator precedence: http://www.tutorialspoint.com/scala/scala_operators.htm
  def expr = "expr" !!! bool_expr | num_expr | text_expr
  def bool_expr = "bool_expr" !!! or | bool_term
  def num_expr = "num_expr" !!! num_equality | num_term
  def text_expr = "text_expr" !!! text_equality

  // operations
  def or = "or" !!! and ~ rep("||" ~ and) ^^ foldExpr(ExprType.Bool)
  def and = "and" !!! equality ~ rep("&&" ~ equality) ^^ foldExpr(ExprType.Bool)

  def equality = "equality" !!! bool_equality | num_equality | text_equality
  def bool_equality = "bool_equality" !!! bool_term ~ rep("==" ~ bool_term | "!=" ~ bool_term) ^^ foldExpr(ExprType.Bool)
  def num_equality = "num_equality" !!! relational ~ rep("==" ~ relational | "!=" ~ relational) ^^ foldExpr(ExprType.Num)
  def text_equality = "text_equality" !!! concat ~ rep("==" ~ concat | "!=" ~ concat) ^^ foldExpr(ExprType.Text)

  def relational = "relational" !!! additive ~ rep(">=" ~ additive | "<=" ~ additive | ">" ~ additive | "<" ~ additive) ^^ foldExpr(ExprType.Num)
  def additive = "additive" !!! multiplicative ~ rep("+" ~ multiplicative | "-" ~ multiplicative) ^^ foldExpr(ExprType.Num)
  def multiplicative = "multiplicative" !!! num_term ~ rep("*" ~ num_term | "/" ~ num_term | "%" ~ num_term) ^^ foldExpr(ExprType.Num)
  def concat = "concat" !!! text ~ rep("+" ~ text) ^^ foldExpr(ExprType.Text)

  def operators = "*" | "/" | "%" | "+" | "-" | "&&" | "||"

  // terms
  def term = "term" !!! bool_term | num_term
  def bool_term = "bool_term" !!! bool | bool_parens | not
  def num_term = "num_term" !!!  num | num_parens | neg

  def not:PackratParser[Expr] = "not" !!! "!" ~> bool_term ^^ (x => UnaryOp("!", x, ExprType.Bool))
  def neg:PackratParser[Expr] = "neg" !!! "-" ~> num_term ^^ (x => UnaryOp("-", x, ExprType.Num))

  def parens:PackratParser[Expr] = "parens" !!! "(" ~> expr <~ ")"
  def bool_parens:PackratParser[Expr] = "bool_parens" !!! "(" ~> bool_expr <~ ")"
  def num_parens:PackratParser[Expr] = "num_parens" !!! "(" ~> num_expr <~ ")"
  def text_parens:PackratParser[Expr] = "text_parens" !!! "(" ~> text_expr <~ ")"

  //values
  def bool: PackratParser[Expr] = "bool" !!!
    "true" ^^^ (Bool(true)) |
    "false" ^^^ (Bool(false)) |
    var_factor

  def num: PackratParser[Expr] = "num" !!!
    floatingPointNumber ^^ (x => Number(x.toDouble)) |
    wholeNumber ^^ (x => Number(x.toDouble)) |
    var_factor

  def text: PackratParser[Expr] = "text" !!!
    stringLiteral ^^ (x => Text(stripQuote(x))) |
    var_factor

  def var_factor: Parser[Expr] = "var_factor" !!!
    id <~ ".asNumber" ^^ (x => NumericVar(x)) |
    id <~ ".asText" ^^ (x => TextVar(x)) |
    id <~ ".asBool" ^^ (x => BoolVar(x)) |
    id ^^ (x => AnyVar(x))

  def id: PackratParser[String] = "id" !!! opt("{") ~> ident <~ opt("}")

  private def stripQuote(s: String) = {
    s.substring(1, s.length - 1)
  }
}

object SimpleEquationParser  extends BoolParser {
  def apply(input: String) : Either[String,Expr] = {

    parseAll("root" !!! expr, input) match {
      case Success(r, _) => Right(r)
      case Failure(msg, _) => Left(msg)
      case Error(msg, _) => Left(msg)
    }
  }
}

trying root at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
trying expr at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
trying bool_expr at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
trying or at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
trying and at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
trying equality at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
trying bool_equality at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
trying bool_term at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
trying bool at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
bool --> [1.1] failure: `true' expected but `(' found

(1+2) > (3+4)
^
trying var_factor at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
trying id at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
id --> [1.1] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `(' found

(1+2) > (3+4)
^
var_factor --> [1.1] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `(' found

(1+2) > (3+4)
^
trying id at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
id --> [1.1] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `(' found

(1+2) > (3+4)
^
trying id at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
id --> [1.1] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `(' found

(1+2) > (3+4)
^
trying id at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
id --> [1.1] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `(' found

(1+2) > (3+4)
^
bool_term --> [1.1] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `(' found

(1+2) > (3+4)
^
trying bool_parens at scala.util.parsing.combinator.PackratParsers$PackratReader@30b7c004
trying bool_expr at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
trying or at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
trying and at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
trying equality at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
trying bool_equality at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
trying bool_term at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
trying bool at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
bool --> [1.2] failure: `true' expected but `1' found

(1+2) > (3+4)
 ^
trying var_factor at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
trying id at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
id --> [1.2] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `1' found

(1+2) > (3+4)
 ^
var_factor --> [1.2] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `1' found

(1+2) > (3+4)
 ^
trying id at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
id --> [1.2] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `1' found

(1+2) > (3+4)
 ^
trying id at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
id --> [1.2] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `1' found

(1+2) > (3+4)
 ^
trying id at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
id --> [1.2] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `1' found

(1+2) > (3+4)
 ^
bool_term --> [1.2] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `1' found

(1+2) > (3+4)
 ^
trying bool_parens at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
bool_parens --> [1.2] failure: `(' expected but `1' found

(1+2) > (3+4)
 ^
trying not at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
not --> [1.2] failure: `!' expected but `1' found

(1+2) > (3+4)
 ^
bool_equality --> [1.2] failure: `!' expected but `1' found

(1+2) > (3+4)
 ^
equality --> [1.2] failure: `!' expected but `1' found

(1+2) > (3+4)
 ^
trying num_equality at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
trying relational at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
trying additive at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
trying multiplicative at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
trying num_term at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
trying num at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@59d016c9
num --> [1.3] parsed: 1
num_term --> [1.3] parsed: Number(1.0)
multiplicative --> [1.3] parsed: (Number(1.0)~List())
trying multiplicative at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@36c88a32
trying num_term at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@36c88a32
trying num at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon$3@36c88a32
num --> [1.5] parsed: 2
num_term --> [1.5] parsed: Number(2.0)
multiplicative --> [1.5] parsed: (Number(2.0)~List())
additive --> [1.5] parsed: (Number(1.0)~List((+~Number(2.0))))
relational --> [1.5] parsed: (BinaryOp(+,Number(1.0),Number(2.0),Num)~List())
num_equality --> [1.5] parsed: (BinaryOp(+,Number(1.0),Number(2.0),Num)~List())
and --> [1.5] parsed: (BinaryOp(+,Number(1.0),Number(2.0),Num)~List())
or --> [1.5] parsed: (BinaryOp(+,Number(1.0),Number(2.0),Num)~List())
bool_expr --> [1.5] parsed: BinaryOp(+,Number(1.0),Number(2.0),Num)
bool_parens --> [1.6] parsed: BinaryOp(+,Number(1.0),Number(2.0),Num)
bool_equality --> [1.6] parsed: (BinaryOp(+,Number(1.0),Number(2.0),Num)~List())
equality --> [1.6] parsed: BinaryOp(+,Number(1.0),Number(2.0),Num)
and --> [1.6] parsed: (BinaryOp(+,Number(1.0),Number(2.0),Num)~List())
or --> [1.6] parsed: (BinaryOp(+,Number(1.0),Number(2.0),Num)~List())
bool_expr --> [1.6] parsed: BinaryOp(+,Number(1.0),Number(2.0),Num)
expr --> [1.6] parsed: BinaryOp(+,Number(1.0),Number(2.0),Num)
root --> [1.6] parsed: BinaryOp(+,Number(1.0),Number(2.0),Num)
Left(`||' expected but `>' found)

---

@Kolmar认为需要使用

num\u expr

解析输入是正确的。下面的解决方案是我提出的，但它感觉没有我想要的那么健壮。问题归结为优先级，但我希望有一种方法可以让解析器在布尔分支失败后继续检查。相反，我在

bool\u equality

之前交换了

equality

解析器的顺序，以检查

num\u equality

：

def equality = "equality" !!! num_equality | bool_equality | text_equality

但是由于

true

和

false

关键字是在布尔分支中定义的，在数值之后进行计算，因此它们被解析为type

AnyVar

，而不是

Bool

。为了解决这个问题，我添加了一个

保留的

解析器，并将

var\u因子

更改为：

def var_factor: Parser[Expr] = "var_factor" !!!
  id <~ ".asNumber" ^^ (x => NumericVar(x)) |
  id <~ ".asText" ^^ (x => TextVar(x)) |
  id <~ ".asBool" ^^ (x => BoolVar(x)) |
  not(reserved) ~> id ^^ (x => AnyVar(x))

def id: PackratParser[String] = "id" !!! opt("{") ~> ident <~ opt("}")
def reserved: Parser[String] = """\b(true|false)\b""".r

def var_factor:Parser[Expr]=“var_factor”！！！
id数字变量（x））|
id TextVar（x））|
id布尔瓦尔（x））|
非（保留）~>id^^（x=>AnyVar（x））
def id:packratPasser[String]=“id”！！！opt（“{”）~>ident注意，
（1+2）
是用
bool_expr
解析的：
bool_parens-->[1.6]已解析：BinaryOp（+，Number（1.0），Number（2.0），Num）
。但是应该使用
num_expr
解析它，以便考虑所需的
关系式
解析器。此外，我认为
foldExpr
中的某些类型是错误的。例如，在
num_equality
中，结果应该是
ExprType.Bool
，但它有
^foldExpr（ExprType.num）
@Kolmar我能够通过交换相等分析器的顺序使它工作，这样
num_equality
在
bool_equality
之前。但是当我这样做时，
true
和
false
被解析为
ident
值，而不是保留的布尔关键字。因此我添加了一个
reserved
parser来纠正这一点。我相信这符合你的建议。@Kolmar至于
foldExpr
，我正在使用这些类型来简化我的求值器逻辑。它告诉求值器的不是输出，而是输入。这可能是一个设计缺陷。我接受建议，但我不想让这个线程偏离正轨。