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Parser.scala
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Parser.scala
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/*
* Copyright (c) 2021 Typelevel
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package cats.parse
import cats.{Eval, FunctorFilter, Monad, Defer, Alternative, FlatMap, Now, MonoidK, Order}
import cats.data.{AndThen, Chain, NonEmptyList}
import cats.implicits._
import scala.collection.immutable.SortedSet
import scala.collection.mutable.ListBuffer
import java.util.Arrays
/** Parser0[A] attempts to extract an `A` value from the given input, potentially moving its offset
* forward in the process.
*
* When calling `parse`, one of three outcomes occurs:
*
* - Success: The parser consumes zero-or-more characters of input and successfully extracts a
* value. The input offset will be moved forward by the number of characters consumed.
*
* - Epsilon failure: The parser fails to extract a value without consuming any characters of
* input. The input offset will not be changed.
*
* - Arresting failure: The parser fails to extract a value but does consume one-or-more
* characters of input. The input offset will be moved forward by the number of characters
* consumed and all parsing will stop (unless a higher-level parser backtracks).
*
* Operations such as `x.orElse(y)` will only consider parser `y` if `x` returns an epsilon
* failure; these methods cannot recover from an arresting failure. Arresting failures can be
* "rewound" using methods such as `x.backtrack` (which converts arresting failures from `x` into
* epsilon failures), or `softProduct(x, y)` (which can rewind successful parses by `x` that are
* followed by epsilon failures for `y`).
*
* Rewinding tends to make error reporting more difficult and can lead to exponential parser
* behavior it is not the default behavior.
*/
sealed abstract class Parser0[+A] { self: Product =>
/** Attempt to parse an `A` value out of `str`.
*
* This method will either return a failure, or else the remaining string and the parsed value.
*
* To require the entire input to be consumed, see `parseAll`.
*/
final def parse(str: String): Either[Parser.Error, (String, A)] = {
val state = new Parser.State(str)
val result = parseMut(state)
val err = state.error
val offset = state.offset
if (err eq null) Right((str.substring(offset), result))
else
Left(
Parser.Error(
offset,
Parser.Expectation.unify(NonEmptyList.fromListUnsafe(err.value.toList))
)
)
}
/** Attempt to parse all of the input `str` into an `A` value.
*
* This method will return a failure unless all of `str` is consumed during parsing.
*
* `p.parseAll(s)` is equivalent to `(p <* Parser.end).parse(s).map(_._2)`.
*/
final def parseAll(str: String): Either[Parser.Error, A] = {
val state = new Parser.State(str)
val result = parseMut(state)
val err = state.error
val offset = state.offset
if (err eq null) {
if (offset == str.length) Right(result)
else
Left(
Parser.Error(
offset,
NonEmptyList(Parser.Expectation.EndOfString(offset, str.length), Nil)
)
)
} else
Left(
Parser.Error(
offset,
Parser.Expectation.unify(NonEmptyList.fromListUnsafe(err.value.toList))
)
)
}
/** Convert epsilon failures into None values.
*
* Normally if a parser fails to consume any input it fails with an epsilon failure. The `?`
* method converts these failures into None values (and wraps other values in `Some(_)`).
*
* If the underlying parser failed with other errors, this parser will still fail.
*/
def ? : Parser0[Option[A]] =
Parser.oneOf0(Parser.map0(this)(Some(_)) :: Parser.optTail)
/** If this parser fails to parse its input with an epsilon error, try the given parser instead.
*
* If this parser fails with an arresting error, the next parser won't be tried.
*
* Backtracking may be used on the left parser to allow the right one to pick up after any error,
* resetting any state that was modified by the left parser.
*
* This method is similar to Parser#orElse but returns Either.
*/
def eitherOr[B](pb: Parser0[B]): Parser0[Either[B, A]] =
Parser.eitherOr0(this, pb)
/** Parse without capturing values.
*
* Calling `void` on a parser can be a significant optimization -- it allows the parser to avoid
* allocating results to return.
*
* Other methods like `as`, `*>`, and `<*` use `void` internally to discard allocations, since
* they will ignore the original parsed result.
*/
def void: Parser0[Unit] =
Parser.void0(this)
/** Return the string matched by this parser.
*
* When parsing an input string that the underlying parser matches, this parser will return the
* matched substring instead of any value that the underlying parser would have returned. It will
* still match exactly the same inputs as the original parser.
*
* This method is very efficient: similarly to `void`, we can avoid allocating results to return.
*/
def string: Parser0[String] =
Parser.string0(this)
/** If this parser fails to match, rewind the offset to the starting point before moving on to
* other parser.
*
* This method converts arresting failures into epsilon failures, which includes rewinding the
* offset to that used before parsing began.
*
* This method will most often be used before calling methods such as `orElse`, `~`, or `flatMap`
* which involve a subsequent parser picking up where this one left off.
*/
def backtrack: Parser0[A] =
Parser.backtrack0(this)
/** Sequence another parser after this one, combining both results into a tuple.
*
* This combinator returns a product of parsers. If this parser successfully produces an `A`
* value, the other parser is run on the remaining input to try to produce a `B` value.
*
* If either parser produces an error the result is an error. Otherwise both extracted values are
* combined into a tuple.
*/
def ~[B](that: Parser0[B]): Parser0[(A, B)] =
Parser.product0(this, that)
/** Compose two parsers, ignoring the values extracted by the left-hand parser.
*
* `x *> y` is equivalent to `(x.void ~ y).map(_._2)`.
*/
def *>[B](that: Parser0[B]): Parser0[B] =
(void ~ that).map(_._2)
/** Compose two parsers, ignoring the values extracted by the right-hand parser.
*
* `x <* y` is equivalent to `(x ~ y.void).map(_._1)`.
*/
def <*[B](that: Parser0[B]): Parser0[A] =
(this ~ that.void).map(_._1)
/** If this parser fails to parse its input with an epsilon error, try the given parser instead.
*
* If this parser fails with an arresting error, the next parser won't be tried.
*
* Backtracking may be used on the left parser to allow the right one to pick up after any error,
* resetting any state that was modified by the left parser.
*/
def orElse[A1 >: A](that: Parser0[A1]): Parser0[A1] =
Parser.oneOf0(this :: that :: Nil)
/** Synonym for orElse Note this is not commutative: if this has an arresting failure we do not
* continue onto the next.
*/
def |[A1 >: A](that: Parser0[A1]): Parser0[A1] =
orElse(that)
/** Transform parsed values using the given function.
*
* This parser will match the same inputs as the underlying parser, using the given function `f`
* to transform the values the underlying parser produces.
*
* If the underlying value is ignored (e.g. `map(_ => ...)`) calling `void` before `map` will
* improve the efficiency of the parser.
*/
def map[B](fn: A => B): Parser0[B] =
Parser.map0(this)(fn)
/** Transform parsed values using the given function, or fail on None
*
* When the function return None, this parser fails This is implemented with select, which makes
* it more efficient than using flatMap
*/
def mapFilter[B](fn: A => Option[B]): Parser0[B] = {
val leftUnit = Left(())
val first = map { a =>
fn(a) match {
case Some(b) => Right(b)
case None => leftUnit
}
}
Parser.select0(first)(Parser.Fail)
}
/** Transform parsed values using the given function, or fail when not defined
*
* When the function is not defined, this parser fails This is implemented with select, which
* makes it more efficient than using flatMap
*/
def collect[B](fn: PartialFunction[A, B]): Parser0[B] =
mapFilter(fn.lift)
/** If the predicate is not true, fail you may want .filter(fn).backtrack so if the filter fn
* fails you can fall through in an oneOf0 or orElse
*
* Without the backtrack, a failure of the function will be an arresting failure.
*/
def filter(fn: A => Boolean): Parser0[A] = {
val leftUnit = Left(())
Parser.select0(this.map { a =>
if (fn(a)) Right(a)
else leftUnit
})(Parser.Fail)
}
/** Dynamically construct the next parser based on the previously parsed value.
*
* Using `flatMap` is very expensive. When possible, you should prefer to use methods such as
* `~`, `*>`, or `<*` when possible, since these are much more efficient.
*/
def flatMap[B](fn: A => Parser0[B]): Parser0[B] =
Parser.flatMap0(this)(fn)
/** Replaces parsed values with the given value.
*/
def as[B](b: B): Parser0[B] =
Parser.as0(this, b)
/** Wrap this parser in a helper class, enabling better composition with `Parser` values.
*
* For example, with `p: Parser0[Int]` and `p1: Parser0[Double]`:
*
* val a1: Parser0[(Int, Double)] = p ~ p1 val a2: Parser[(Int, Double)] = p.with1 ~ p1
*
* val b1: Parser0[Double] = p *> p1 val b2: Parser[Double] = p.with1 *> p1
*
* val c1: Parser0[Int] = p <* p1 val c2: Parser[Int] = p.with1 <* p1
*
* Without using `with1`, these methods will return `Parser0` values since they are not known to
* return `Parser` values instead.
*/
def with1: Parser.With1[A] =
new Parser.With1(this)
/** Wrap this parser in a helper class, to enable backtracking during composition.
*
* This wrapper changes the behavior of `~`, `<*` and `*>`. Normally no backtracking occurs.
* Using `soft` on the left-hand side will enable backtracking if the right-hand side returns an
* epsilon failure (but not in any other case).
*
* For example, `(x ~ y)` will never backtrack. But with `(x.soft ~ y)`, if `x` parses
* successfully, and `y` returns an epsilon failure, the parser will "rewind" to the point before
* `x` began.
*/
def soft: Parser.Soft0[A] =
new Parser.Soft0(this)
/** Return a parser that succeeds (consuming nothing, and extracting nothing) if the current
* parser would fail.
*
* This parser expects the underlying parser to fail, and will unconditionally backtrack after
* running it.
*/
def unary_! : Parser0[Unit] =
Parser.not(this)
/** Return a parser that succeeds (consuming nothing and extracting nothing) if the current parser
* would also succeed.
*
* This parser expects the underlying parser to succeed, and will unconditionally backtrack after
* running it.
*/
def peek: Parser0[Unit] =
Parser.peek(this)
/** Use this parser to parse between values.
*
* Parses `b` followed by `this` and `c`. Returns only the values extracted by `this` parser.
*/
def between(b: Parser0[Any], c: Parser0[Any]): Parser0[A] =
(b.void ~ (this ~ c.void)).map { case (_, (a, _)) => a }
/** Use this parser to parse surrounded by values.
*
* This is the same as `between(b, b)`
*/
def surroundedBy(b: Parser0[Any]): Parser0[A] =
between(b, b)
/** Add a string context to any Errors on parsing this is useful for debugging failing parsers.
*/
def withContext(str: String): Parser0[A] =
Parser.withContext0(this, str)
/** Internal (mutable) parsing method.
*
* This method should only be called internally by parser instances.
*/
private[parse] def parseMut(state: Parser.State): A
/** This method overrides `Object#hashCode` to cache its result for performance reasons.
*/
override lazy val hashCode: Int = scala.runtime.ScalaRunTime._hashCode(this)
}
/** Parser[A] is a Parser0[A] that will always consume one-or-more characters on a successful parse.
*
* Since Parser is guaranteed to consume input it provides additional methods which would be unsafe
* when used on parsers that succeed without consuming input, such as `rep0`.
*
* When a Parser is composed with a Parser0 the result is usually a Parser. Parser overrides many
* of Parser0's methods to refine the return type. In other cases, callers may need to use the
* `with1` helper method to refine the type of their expressions.
*
* Parser doesn't provide any additional guarantees over Parser0 on what kind of parsing failures
* it can return.
*/
sealed abstract class Parser[+A] extends Parser0[A] { self: Product =>
/** This method overrides `Parser0#filter` to refine the return type.
*/
override def filter(fn: A => Boolean): Parser[A] = {
val leftUnit = Left(())
Parser.select(this.map { a =>
if (fn(a)) Right(a)
else leftUnit
})(Parser.Fail)
}
/** This method overrides `Parser0#void` to refine the return type.
*/
override def void: Parser[Unit] =
Parser.void(this)
/** This method overrides `Parser0#string` to refine the return type.
*/
override def string: Parser[String] =
Parser.string(this)
/** This method overrides `Parser0#backtrack` to refine the return type.
*/
override def backtrack: Parser[A] =
Parser.backtrack(this)
/** a version of eitherOr when both sides are not Parser0
*/
def eitherOr[B](pb: Parser[B]): Parser[Either[B, A]] =
Parser.eitherOr(this, pb)
/** This method overrides `Parser0#~` to refine the return type.
*/
override def ~[B](that: Parser0[B]): Parser[(A, B)] =
Parser.product10(this, that)
/** This method overrides `Parser0#*>` to refine the return type.
*/
override def *>[B](that: Parser0[B]): Parser[B] =
(void ~ that).map(_._2)
/** This method overrides `Parser0#<*` to refine the return type.
*/
override def <*[B](that: Parser0[B]): Parser[A] =
(this ~ that.void).map(_._1)
/** This method overrides `Parser0#collect` to refine the return type.
*/
override def collect[B](fn: PartialFunction[A, B]): Parser[B] =
mapFilter(fn.lift)
/** This method overrides `Parser0#map` to refine the return type.
*/
override def map[B](fn: A => B): Parser[B] =
Parser.map(this)(fn)
/** This method overrides `Parser0#mapFilter` to refine the return type.
*/
override def mapFilter[B](fn: A => Option[B]): Parser[B] = {
val leftUnit = Left(())
val first = map { a =>
fn(a) match {
case Some(b) => Right(b)
case None => leftUnit
}
}
Parser.select(first)(Parser.Fail)
}
/** This method overrides `Parser0#flatMap` to refine the return type.
*/
override def flatMap[B](fn: A => Parser0[B]): Parser[B] =
Parser.flatMap10(this)(fn)
/** This method overrides `Parser0#as` to refine the return type.
*/
override def as[B](b: B): Parser[B] =
Parser.as(this, b)
/** If this parser fails to parse its input with an epsilon error, try the given parser instead.
*
* This method is similar to Parser0#orElse, but since both arguments are known to be Parser
* values, the result is known to be a Parser as well.
*/
def orElse[A1 >: A](that: Parser[A1]): Parser[A1] =
Parser.oneOf(this :: that :: Nil)
/** Synonym for orElse Note this is not commutative: if this has an arresting failure we do not
* continue onto the next.
*/
def |[A1 >: A](that: Parser[A1]): Parser[A1] =
orElse(that)
/** Use this parser to parse zero-or-more values.
*
* This parser may succeed without consuming input in the case where zero values are parsed.
*
* If the underlying parser hits an arresting failure, the entire parse is also an arresting
* failure. If the underlying parser hits an epsilon failure, the parsed values (if any) are
* returned in a list as a successful parse.
*/
def rep0: Parser0[List[A]] = repAs0
/** Use this parser to parse at least `min` values (where `min >= 0`).
*
* If `min` is zero, this parser may succeed without consuming input in the case where zero
* values are parsed. If `min` is known to be greater than zero, consider using `rep(min)`
* instead.
*
* Like `rep0`, arresting failures in the underlying parser will result in an arresting failure.
* Unlike `rep0`, this method may also return an arresting failure if it has not parsed at least
* `min` values (but has consumed input).
*/
def rep0(min: Int): Parser0[List[A]] =
if (min == 0) rep0
else repAs(min)
/** Repeat the parser `min` or more times, but no more than `max`
*
* The parser fails if it can't match at least `min` times After repeating the parser `max`
* times, the parser completes successfully
*
* @throws java.lang.IllegalArgumentException
* if min < 0 or max < min
*/
def rep0(min: Int, max: Int): Parser0[List[A]] =
if (min == 0) repAs0(max)
else repAs(min, max)
/** Use this parser to parse one-or-more values.
*
* This parser behaves like `rep0`, except that it must produce at least one value, and is
* guaranteed to consume input on successful parses.
*/
def rep: Parser[NonEmptyList[A]] = repAs
/** Use this parser to parse at least `min` values (where `min >= 1`).
*
* This method behaves likes `rep`, except that if fewer than `min` values are produced an
* arresting failure will be returned.
*/
def rep(min: Int): Parser[NonEmptyList[A]] =
repAs(min = min)
/** Repeat the parser `min` or more times, but no more than `max`
*
* The parser fails if it can't match at least `min` times After repeating the parser `max`
* times, the parser completes successfully
*
* @throws java.lang.IllegalArgumentException
* if min < 1 or max < min
*/
def rep(min: Int, max: Int): Parser[NonEmptyList[A]] =
repAs(min = min, max = max)
/** Repeat the parser 0 or more times
*
* @note
* this can wind up parsing nothing
*/
def repAs0[B](implicit acc: Accumulator0[A, B]): Parser0[B] =
Parser.repAs0(this)(acc)
/** Repeat the parser 0 or more times, but no more than `max`
*
* It may seem weird to accept 0 here, but without, composing this method becomes more complex.
* Since and empty parse is possible for this method, we do allow max = 0
*
* @throws java.lang.IllegalArgumentException
* if max < 0
*
* @note
* this can wind up parsing nothing
*/
def repAs0[B](max: Int)(implicit acc: Accumulator0[A, B]): Parser0[B] =
Parser.repAs0(this, max = max)(acc)
/** Repeat the parser 1 or more times
*/
def repAs[B](implicit acc: Accumulator[A, B]): Parser[B] =
repAs(min = 1)
/** Repeat the parser `min` or more times
*
* The parser fails if it can't match at least `min` times
*
* @throws java.lang.IllegalArgumentException
* if min < 1
*/
def repAs[B](min: Int)(implicit acc: Accumulator[A, B]): Parser[B] =
Parser.repAs(this, min = min)(acc)
/** Repeat the parser `min` or more times, but no more than `max`
*
* The parser fails if it can't match at least `min` times After repeating the parser `max`
* times, the parser completes successfully
*
* @throws java.lang.IllegalArgumentException
* if min < 1 or max < min
*/
def repAs[B](min: Int, max: Int)(implicit acc: Accumulator[A, B]): Parser[B] =
Parser.repAs(this, min = min, max = max)(acc)
/** Repeat the parser exactly `times` times
*
* @throws java.lang.IllegalArgumentException
* if times < 1
*/
def repExactlyAs[B](times: Int)(implicit acc: Accumulator[A, B]): Parser[B] =
Parser.repExactlyAs(this, times = times)(acc)
/** Repeat 0 or more times with a separator
*/
def repSep0(sep: Parser0[Any]): Parser0[List[A]] =
Parser.repSep0(this, sep)
/** Repeat `min` or more times with a separator.
*
* @throws java.lang.IllegalArgumentException
* if `min < 0`
*/
def repSep0(min: Int, sep: Parser0[Any]): Parser0[List[A]] =
Parser.repSep0(this, min = min, sep = sep)
/** Repeat `min` or more, up to `max` times with a separator.
*
* @throws java.lang.IllegalArgumentException
* if `min < 0` or `max < min`
*/
def repSep0(min: Int, max: Int, sep: Parser0[Any]): Parser0[List[A]] =
Parser.repSep0(this, min = min, max = max, sep = sep)
/** Repeat 1 or more times with a separator
*/
def repSep(sep: Parser0[Any]): Parser[NonEmptyList[A]] =
Parser.repSep(this, sep)
/** Repeat `min` or more times with a separator, at least once.
*
* @throws java.lang.IllegalArgumentException
* if `min <= 0`
*/
def repSep(min: Int, sep: Parser0[Any]): Parser[NonEmptyList[A]] =
Parser.repSep(this, min = min, sep = sep)
/** Repeat `min` or more, up to `max` times with a separator, at least once.
*
* @throws java.lang.IllegalArgumentException
* if `min <= 0` or `max < min`
*/
def repSep(min: Int, max: Int, sep: Parser0[Any]): Parser[NonEmptyList[A]] =
Parser.repSep(this, min = min, max = max, sep = sep)
/** Repeat this parser 0 or more times until `end` Parser succeeds.
*/
def repUntil0(end: Parser0[Any]): Parser0[List[A]] =
Parser.repUntil0(this, end)
/** Repeat this parser 1 or more times until `end` Parser succeeds.
*/
def repUntil(end: Parser0[Any]): Parser[NonEmptyList[A]] =
Parser.repUntil(this, end)
/** Repeat this parser 0 or more times until `end` Parser succeeds.
*/
def repUntilAs0[B](end: Parser0[Any])(implicit acc: Accumulator0[A, B]): Parser0[B] =
Parser.repUntilAs0(this, end)
/** Repeat this parser 1 or more times until `end` Parser succeeds.
*/
def repUntilAs[B](end: Parser0[Any])(implicit acc: Accumulator[A, B]): Parser[B] =
Parser.repUntilAs(this, end)
/** This method overrides `Parser0#between` to refine the return type
*/
override def between(b: Parser0[Any], c: Parser0[Any]): Parser[A] =
(b.void.with1 ~ (this ~ c.void)).map { case (_, (a, _)) => a }
/** This method overrides `Parser0#surroundedBy` to refine the return type
*/
override def surroundedBy(b: Parser0[Any]): Parser[A] =
between(b, b)
/** This method overrides `Parser0#soft` to refine the return type.
*/
override def soft: Parser.Soft[A] =
new Parser.Soft(this)
/** This method overrides `Parser0#withContext` to refine the return type. add a string context to
* any Errors on parsing this is useful for debugging failing parsers.
*/
override def withContext(str: String): Parser[A] =
Parser.withContext(this, str)
}
object Parser {
/** An expectation reports the kind or parsing error and where it occured.
*/
sealed abstract class Expectation {
def offset: Int
/** This is a reverse order stack (most recent context first) of this parsing error
*/
def context: List[String] =
this match {
case Expectation.WithContext(ctx, inner) =>
ctx :: inner.context
case _ => Nil
}
}
object Expectation {
case class OneOfStr(offset: Int, strs: List[String]) extends Expectation
// expected a character in a given range
case class InRange(offset: Int, lower: Char, upper: Char) extends Expectation
case class StartOfString(offset: Int) extends Expectation
case class EndOfString(offset: Int, length: Int) extends Expectation
case class Length(offset: Int, expected: Int, actual: Int) extends Expectation
case class ExpectedFailureAt(offset: Int, matched: String) extends Expectation
// this is the result of oneOf0(Nil) at a given location
case class Fail(offset: Int) extends Expectation
case class FailWith(offset: Int, message: String) extends Expectation
case class WithContext(contextStr: String, expect: Expectation) extends Expectation {
def offset: Int = expect.offset
}
implicit val catsOrderExpectation: Order[Expectation] =
new Order[Expectation] {
override def compare(left: Expectation, right: Expectation): Int = {
val c = Integer.compare(left.offset, right.offset)
if (c != 0) c
else if (left == right) 0
else {
// these are never equal
(left, right) match {
case (OneOfStr(_, s1), OneOfStr(_, s2)) => s1.compare(s2)
case (OneOfStr(_, _), _) => -1
case (InRange(_, _, _), OneOfStr(_, _)) => 1
case (InRange(_, l1, u1), InRange(_, l2, u2)) =>
val c1 = Character.compare(l1, l2)
if (c1 == 0) Character.compare(u1, u2)
else c1
case (InRange(_, _, _), _) => -1
case (StartOfString(_), OneOfStr(_, _) | InRange(_, _, _)) => 1
case (StartOfString(_), _) =>
-1 // if they have the same offset, already handled above
case (
EndOfString(_, _),
OneOfStr(_, _) | InRange(_, _, _) | StartOfString(_)
) =>
1
case (EndOfString(_, l1), EndOfString(_, l2)) =>
Integer.compare(l1, l2)
case (EndOfString(_, _), _) => -1
case (
Length(_, _, _),
OneOfStr(_, _) | InRange(_, _, _) | StartOfString(_) | EndOfString(_, _)
) =>
1
case (Length(_, e1, a1), Length(_, e2, a2)) =>
val c1 = Integer.compare(e1, e2)
if (c1 == 0) Integer.compare(a1, a2)
else c1
case (Length(_, _, _), _) => -1
case (ExpectedFailureAt(_, _), Fail(_) | FailWith(_, _) | WithContext(_, _)) => -1
case (ExpectedFailureAt(_, m1), ExpectedFailureAt(_, m2)) =>
m1.compare(m2)
case (ExpectedFailureAt(_, _), _) => 1
case (Fail(_), FailWith(_, _) | WithContext(_, _)) => -1
case (Fail(_), _) => 1
case (FailWith(_, _), WithContext(_, _)) => -1
case (FailWith(_, s1), FailWith(_, s2)) =>
s1.compare(s2)
case (FailWith(_, _), _) => 1
case (WithContext(lctx, lexp), WithContext(rctx, rexp)) =>
val c = compare(lexp, rexp)
if (c != 0) c
else lctx.compareTo(rctx)
case (WithContext(_, _), _) => 1
}
}
}
}
private def mergeInRange(irs: List[InRange]): List[InRange] = {
@annotation.tailrec
def merge(rs: List[InRange], aux: Chain[InRange] = Chain.empty): Chain[InRange] =
rs match {
case x :: y :: rest =>
if (y.lower.toInt > x.upper.toInt + 1) merge(y :: rest, aux :+ x)
else merge(InRange(x.offset, x.lower, x.upper max y.upper) :: rest, aux)
case _ =>
aux ++ Chain.fromSeq(rs.reverse)
}
merge(irs.sortBy(_.lower)).toList
}
private def mergeOneOfStr(ooss: List[OneOfStr]): Option[OneOfStr] =
if (ooss.isEmpty) None
else {
val ssb = SortedSet.newBuilder[String]
ooss.foreach(ssb ++= _.strs)
Some(OneOfStr(ooss.head.offset, ssb.result().toList))
}
@annotation.tailrec
private def stripContext(ex: Expectation): Expectation =
ex match {
case WithContext(_, inner) => stripContext(inner)
case _ => ex
}
@annotation.tailrec
private def addContext(revCtx: List[String], ex: Expectation): Expectation =
revCtx match {
case Nil => ex
case h :: tail => addContext(tail, WithContext(h, ex))
}
/** Sort, dedup and unify ranges for the errors accumulated This is called just before finally
* returning an error in Parser.parse
*/
def unify(errors: NonEmptyList[Expectation]): NonEmptyList[Expectation] = {
val result = errors
.groupBy { ex => (ex.offset, ex.context) }
.iterator
.flatMap { case ((_, ctx), list) =>
val rm = ListBuffer.empty[InRange]
val om = ListBuffer.empty[OneOfStr]
val fails = ListBuffer.empty[Fail]
val others = ListBuffer.empty[Expectation]
var items = list.toList
while (items.nonEmpty) {
stripContext(items.head) match {
case ir: InRange => rm += ir
case os: OneOfStr => om += os
case fail: Fail => fails += fail
case other => others += other
}
items = items.tail
}
// merge all the ranges:
val rangeMerge = mergeInRange(rm.toList)
// merge the OneOfStr
val oossMerge = mergeOneOfStr(om.toList)
val errors = others.toList reverse_::: (oossMerge ++: rangeMerge)
val finals = if (errors.isEmpty) fails.toList else errors
if (ctx.nonEmpty) {
val revCtx = ctx.reverse
finals.map(addContext(revCtx, _))
} else finals
}
.toList
NonEmptyList.fromListUnsafe(result.distinct.sorted)
}
}
/** Represents where a failure occurred and all the expectations that were broken
*/
final case class Error(failedAtOffset: Int, expected: NonEmptyList[Expectation]) {
def offsets: NonEmptyList[Int] =
expected.map(_.offset).distinct
}
/** Enables syntax to access product01, product and flatMap01 This helps us build Parser instances
* when starting from a Parser0
*/
final class With1[+A](val parser: Parser0[A]) extends AnyVal {
/** parser then that. Since that is a Parser the result is
*/
def ~[B](that: Parser[B]): Parser[(A, B)] =
Parser.product01(parser, that)
/** This is the usual monadic composition, but you should much prefer to use ~ or Apply.product,
* *>, <*, etc if you can since it is much more efficient. This has to call fn on each parse,
* which could be a lot of extra work is you already know the result as is the case for ~
*/
def flatMap[B](fn: A => Parser[B]): Parser[B] =
Parser.flatMap01(parser)(fn)
/** parser then that. Since that is a Parser the result is
*/
def *>[B](that: Parser[B]): Parser[B] =
product01(void0(parser), that).map(_._2)
/** parser then that. Since that is a Parser the result is
*/
def <*[B](that: Parser[B]): Parser[A] =
product01(parser, void(that)).map(_._1)
/** If we can parse this then that, do so, if we fail that without consuming, rewind before this
* without consuming. If either consume 1 or more, do not rewind
*/
def soft: Soft01[A] =
new Soft01(parser)
/** parse between values. Since values are `Parser` the result is
*/
def between(b: Parser[Any], c: Parser[Any]): Parser[A] =
(b.void ~ (parser ~ c.void)).map { case (_, (a, _)) => a }
/** parse surrounded by that. Since that is a Parser the result is
*/
def surroundedBy(that: Parser[Any]): Parser[A] =
between(that, that)
}
/** If we can parse this then that, do so, if we fail that without consuming, rewind before this
* without consuming. If either consume 1 or more, do not rewind
*/
sealed class Soft0[+A](parser: Parser0[A]) {
def ~[B](that: Parser0[B]): Parser0[(A, B)] =
softProduct0(parser, that)
def *>[B](that: Parser0[B]): Parser0[B] =
softProduct0(void0(parser), that).map(_._2)
def <*[B](that: Parser0[B]): Parser0[A] =
softProduct0(parser, void0(that)).map(_._1)
/** If we can parse this then that, do so, if we fail that without consuming, rewind before this
* without consuming. If either consume 1 or more, do not rewind
*/
def with1: Soft01[A] =
new Soft01(parser)
/** Like regular between, but uses soft products This is particularly useful with whitespace and
* separators, e.g. a separator might be `char(',').soft.surroundedBy(whitespace0)`
*/
def between(b: Parser0[Any], c: Parser0[Any]): Parser0[A] =
(b.void.soft ~ (parser.soft ~ c.void)).map { case (_, (a, _)) => a }
/** Use this parser to parse surrounded by values using soft products
*
* This is the same as `between(b, b)`
*/
def surroundedBy(b: Parser0[Any]): Parser0[A] =
between(b, b)
}
/** If we can parse this then that, do so, if we fail that without consuming, rewind before this
* without consuming. If either consume 1 or more, do not rewind
*/
final class Soft[+A](parser: Parser[A]) extends Soft0(parser) {
override def ~[B](that: Parser0[B]): Parser[(A, B)] =
softProduct10(parser, that)
override def *>[B](that: Parser0[B]): Parser[B] =
softProduct10(void(parser), that).map(_._2)
override def <*[B](that: Parser0[B]): Parser[A] =
softProduct10(parser, void0(that)).map(_._1)
override def between(b: Parser0[Any], c: Parser0[Any]): Parser[A] =
(b.void.with1.soft ~ (parser.soft ~ c.void)).map { case (_, (a, _)) => a }
override def surroundedBy(b: Parser0[Any]): Parser[A] =
between(b, b)
}
/** If we can parse this then that, do so, if we fail that without consuming, rewind before this
* without consuming. If either consume 1 or more, do not rewind
*/
final class Soft01[+A](val parser: Parser0[A]) extends AnyVal {
def ~[B](that: Parser[B]): Parser[(A, B)] =
softProduct01(parser, that)
def *>[B](that: Parser[B]): Parser[B] =
softProduct01(void0(parser), that).map(_._2)
def <*[B](that: Parser[B]): Parser[A] =
softProduct01(parser, void(that)).map(_._1)
def between(b: Parser[Any], c: Parser[Any]): Parser[A] =
(b.void.soft ~ (parser.soft ~ c.void)).map { case (_, (a, _)) => a }
def surroundedBy(b: Parser[Any]): Parser[A] =
between(b, b)
}
/** Don't advance in the parsed string, just return a This is used by the Applicative typeclass.
*/
def pure[A](a: A): Parser0[A] =
Impl.Pure(a)
/** Parse a given string, in a case-insensitive manner, or fail. This backtracks on failure this
* is an error if the string is empty
*/
def ignoreCase(str: String): Parser[Unit] =
if (str.length == 1) {
ignoreCaseChar(str.charAt(0))
} else Impl.IgnoreCase(str.toLowerCase)
/** Ignore the case of a single character If you want to know if it is upper or lower, use .string
* to capture the string and then map to process the result.
*/
def ignoreCaseChar(c: Char): Parser[Unit] =
charIn(c.toLower, c.toUpper).void
/** Parse a given string or fail. This backtracks on failure this is an error if the string is
* empty
*/
def string(str: String): Parser[Unit] =
if (str.length == 1) char(str.charAt(0))
else Impl.Str(str)
/** Parse a potentially empty string or fail. This backtracks on failure
*/
def string0(str: String): Parser0[Unit] =
if (str.length == 0) unit
else string(str)
/** Parse a potentially empty string, in a case-insensitive manner, or fail. This backtracks on
* failure
*/
def ignoreCase0(str: String): Parser0[Unit] =
if (str.length == 0) unit
else ignoreCase(str)
/** go through the list of parsers trying each as long as they are epsilon failures (don't
* advance) see @backtrack if you want to do backtracking.
*
* This is the same as parsers.foldLeft(fail)(_.orElse(_))
*
* recommended style: oneOf(p1 :: p2 :: p3 :: Nil) rather than oneOf(List(p1, p2, p3))
*
* Note: order matters here, since we don't backtrack by default.
*/
def oneOf[A](parsers: List[Parser[A]]): Parser[A] = {
@annotation.tailrec
def flatten(ls: List[Parser[A]], acc: ListBuffer[Parser[A]]): List[Parser[A]] =
ls match {
case Nil => acc.toList.distinct
case Impl.OneOf(ps) :: rest =>
flatten(ps ::: rest, acc)
case Impl.Fail() :: rest =>
flatten(rest, acc)