Scala 组合器 JavaTokennParsers '||'预期但找到“>”
Scala Combinators JavaTokennParsers '||' expected but '>' found
当我运行这个测试：
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。有什么建议么？以下是 class 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 !! = log(p)(name) // for debugging
//def !! = 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)
}
}
}
日志跟踪：
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$$anon@59d016c9
trying or at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying and at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying equality at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying bool_equality at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying bool_term at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying bool at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
bool --> [1.2] failure: `true' expected but `1' found
(1+2) > (3+4)
^
trying var_factor at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying id at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
id --> [1.2] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `1' found
(1+2) > (3+4)
^
var_factor --> [1.2] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `1' found
(1+2) > (3+4)
^
trying id at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@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$$anon@59d016c9
id --> [1.2] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `1' found
(1+2) > (3+4)
^
trying id at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@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$$anon@59d016c9
bool_parens --> [1.2] failure: `(' expected but `1' found
(1+2) > (3+4)
^
trying not at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@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$$anon@59d016c9
trying relational at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying additive at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying multiplicative at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying num_term at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying num at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@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$$anon@36c88a32
trying num_term at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@36c88a32
trying num at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@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 说输入需要用num_expr解析是正确的。下面的解决方案是我想出的，但感觉不如我想要的那么可靠。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，我交换了 equality 解析器的顺序以在 bool_equality:
之前检查 num_equality
def equality = "equality" !!! num_equality | bool_equality | text_equality
但是因为true和false关键字定义在boolean分支中，它是在数值之后求值的，所以它们被解析为类型AnyVar而不是Bool .为了解决这个问题，我添加了一个 reserved 解析器并将 var_factor 更改为以下内容：
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
我目前有大约 70 个测试都通过了。我仍然乐于接受有关更强大的解决方案（不那么脆弱）的建议，但这似乎目前运行良好。
当我运行这个测试：
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。有什么建议么？以下是 class 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 !! = log(p)(name) // for debugging
//def !! = 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)
}
}
}
日志跟踪：
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@59d016c9
trying or at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying and at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying equality at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying bool_equality at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying bool_term at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying bool at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
bool --> [1.2] failure: `true' expected but `1' found
(1+2) > (3+4)
^
trying var_factor at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying id at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@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$$anon@59d016c9
id --> [1.2] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `1' found
(1+2) > (3+4)
^
trying id at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@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$$anon@59d016c9
id --> [1.2] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `1' found
(1+2) > (3+4)
^
bool_term --> [1.2] failure: string matching regex `\p{javaJavaIdentifierStart}\p{javaJavaIdentifierPart}*' expected but `1' found
(1+2) > (3+4)
^
trying bool_parens at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
bool_parens --> [1.2] failure: `(' expected but `1' found
(1+2) > (3+4)
^
trying not at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
not --> [1.2] failure: `!' expected but `1' found
(1+2) > (3+4)
^
bool_equality --> [1.2] failure: `!' expected but `1' found
(1+2) > (3+4)
^
equality --> [1.2] failure: `!' expected but `1' found
(1+2) > (3+4)
^
trying num_equality at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying relational at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying additive at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying multiplicative at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying num_term at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
trying num at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@59d016c9
num --> [1.3] parsed: 1
num_term --> [1.3] parsed: Number(1.0)
multiplicative --> [1.3] parsed: (Number(1.0)~List())
trying multiplicative at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@36c88a32
trying num_term at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@36c88a32
trying num at scala.util.parsing.combinator.PackratParsers$PackratReader$$anon@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 说输入需要用num_expr解析是正确的。下面的解决方案是我想出的，但感觉不如我想要的那么可靠。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，我交换了 equality 解析器的顺序以在 bool_equality:
num_equality
def equality = "equality" !!! num_equality | bool_equality | text_equality
但是因为true和false关键字定义在boolean分支中，它是在数值之后求值的，所以它们被解析为类型AnyVar而不是Bool .为了解决这个问题，我添加了一个 reserved 解析器并将 var_factor 更改为以下内容：
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
我目前有大约 70 个测试都通过了。我仍然乐于接受有关更强大的解决方案（不那么脆弱）的建议，但这似乎目前运行良好。