From 6b801413fdb089d5084c64485867b9de7187a869 Mon Sep 17 00:00:00 2001
From: Martin Odersky
+ * The reason for this is that the sequential composition combinator (`~') combines its constituents
+ * into a ~. When several `~'s are combined, this results in nested `~'s (to the left).
+ * The `flatten*' coercions makes it easy to apply an `n'-argument function to a nested ~ of
+ * depth (`n-1')
+ * The `headOptionTailToFunList' converts a function that takes a List[A] to a function that
+ * accepts a ~[A, Option[List[A]]] (this happens when, e.g., parsing something of the following
+ * shape: p ~ opt("." ~ repsep(p, ".")) -- where `p' is a parser that yields an A)
+ *
+ * It requires the type of the elements these parsers should parse
+ * (each parser is polymorphic in the type of result it produces).
+ *
+ * There are two aspects to the result of a parser: (1) success or failure,
+ * and (2) the result. A
+ * The term ``parser combinator'' refers to the fact that these parsers
+ * are constructed from primitive parsers and composition operators, such
+ * as sequencing, alternation, optionality, repetition, lifting, and so on.
+ *
+ * A ``primitive parser'' is a parser that accepts or rejects a single
+ * piece of input, based on a certain criterion, such as whether the
+ * input...
+ *
+ * Even more primitive parsers always produce the same result, irrespective
+ * of the input.
+ * Parsers
is a component that provides generic
+ * parser combinators.
+ * Parser[T]
provides both kinds of
+ * information.
+ *
+ *
+ *
+ * @provides Input = Reader[Elem] + * The type of input the parsers in this component expect.
+ *+ * @provides Parser[+T] extends (Input => ParseResult[T]) + * Essentially, a `Parser[T]' is a function from `Input' to `ParseResult[T]'.
+ *+ * @provides ParseResult[+T] is like an `Option[T]', in the sense that it is either + * `Success[T]', which consists of some result (:T) (and the rest of the input) or + * `Failure[T]', which provides an error message (and the rest of the input).
+ * + * @author Martin Odersky, Iulian Dragos, Adriaan Moors + */ +trait Parsers { + /** the type of input elements */ + type Elem + + /** The parser input is an abstract reader of input elements */ + type Input = Reader[Elem] + + /** A base class for parser results. + * A result is either successful or not (failure may be fatal, i.e., + * an Error, or not, i.e., a Failure) + * On success, provides a result of typeT
.
+ */
+ sealed abstract class ParseResult[+T] {
+ /** Functional composition of ParseResults
+ *
+ * @param `f' the function to be lifted over this result
+ * @return `f' applied to the result of this `ParseResult', packaged up as a new `ParseResult'
+ */
+ def map[U](f: T => U): ParseResult[U]
+
+ /** Partial functional composition of ParseResults
+ *
+ * @param `f' the partial function to be lifted over this result
+ * @param error a function that takes the same argument as `f' and produces an error message
+ * to explain why `f' wasn't applicable (it is called when this is the case)
+ * @return if `f' f is defined at the result in this `ParseResult',
+ * `f' applied to the result of this `ParseResult', packaged up as a new `ParseResult'.
+ * If `f' is not defined, `Failure'.
+ */
+ def mapPartial[U](f: PartialFunction[T, U], error: T => String): ParseResult[U]
+
+ def isEmpty = !successful
+
+ /** Returns the embedded result */
+ def get: T
+
+ def getOrElse[B >: T](default: => B): B =
+ if (isEmpty) default else this.get
+
+ val next: Input
+
+ val successful: Boolean
+ }
+
+ /** The success case of ParseResult: contains the result and the remaining input.
+ *
+ * @param result The parser's output
+ * @param next The parser's remaining input
+ */
+ case class Success[+T](result: T, override val next: Input) extends ParseResult[T] {
+ def map[U](f: T => U) = Success(f(result), next)
+ def mapPartial[U](f: PartialFunction[T, U], error: T => String): ParseResult[U]
+ = if(f.isDefinedAt(result)) Success(f(result), next)
+ else Failure(error(result), next)
+
+ def get: T = result
+
+ /** The toString method of a Success */
+ override def toString = "["+next.pos+"] parsed: "+result
+
+ val successful = true
+ }
+
+ /** A common super-class for unsuccessful parse results
+ */
+ sealed abstract class NoSuccess(val msg: String, override val next: Input) extends ParseResult[Nothing] { // when we don't care about the difference between Failure and Error
+ val successful = false
+
+ def map[U](f: Nothing => U) = this
+ def mapPartial[U](f: PartialFunction[Nothing, U], error: Nothing => String): ParseResult[U] = this
+
+ def get: Nothing = error("No result when parsing failed")
+ }
+
+ /** The failure case of ParseResult: contains an error-message and the remaining input.
+ * Parsing will back-track when a failure occurs.
+ *
+ * @param msg An error message string describing the failure.
+ * @param next The parser's unconsumed input at the point where the failure occurred.
+ */
+ case class Failure(override val msg: String, override val next: Input) extends NoSuccess(msg, next) {
+ /** The toString method of a Failure yields an error message */
+ override def toString = "["+next.pos+"] failure: "+msg+"\n\n"+next.pos.longString
+ }
+
+ /** The fatal failure case of ParseResult: contains an error-message and the remaining input.
+ * No back-tracking is done when a parser returns an `Error'
+ *
+ * @param msg An error message string describing the error.
+ * @param next The parser's unconsumed input at the point where the error occurred.
+ */
+ case class Error(override val msg: String, override val next: Input) extends NoSuccess(msg, next) {
+ /** The toString method of an Error yields an error message */
+ override def toString = "["+next.pos+"] error: "+msg+"\n\n"+next.pos.longString
+ }
+
+ /** The root class of parsers.
+ * Parsers are functions from the Input type to ParseResult
+ */
+ abstract class Parser[+T] extends (Input => ParseResult[T]) {
+ /** An unspecified method that defines the behaviour of this parser.
+ */
+ def apply(in: Input): ParseResult[T]
+
+
+ // the operator formerly known as +++, ++, &, but now, behold the venerable ~
+ // it's short, light (looks like whitespace), has few overloaded meaning (thanks to the recent change from ~ to unary_~)
+ // and we love it!
+
+ /** A parser combinator for sequential composition
+ *
+ * `p ~ q' succeeds if `p' succeeds and `q' succeeds on the input + * left over by `p'.
+ * + * @param q a parser that will be executed after `p' (this parser) succeeds + * @return a `Parser' that -- on success -- returns a `~' (like a Pair, but easier to pattern match on) + * that contains the result of `p' and that of `q'. + * The resulting parser fails if either `p' or `q' fails. + */ + def ~ [U](q: => Parser[U]): Parser[~[T, U]] = new Parser[~[T, U]] { + def apply(in: Input) = seq(Parser.this, q)((x, y) => new ~(x,y))(in) + override def toString = "~" + } + + def ~> [U](q: => Parser[U]): Parser[U] = new Parser[U] { + def apply(in: Input) = seq(Parser.this, q)((x, y) => y)(in) + override def toString = "~" + } + + def <~ [U](q: => Parser[U]): Parser[T] = new Parser[T] { + def apply(in: Input) = seq(Parser.this, q)((x, y) => x)(in) + override def toString = "~" + } + + /* not really useful: V cannot be inferred because Parser is covariant in first type parameter (V is always trivially Nothing) + def ~~ [U, V](q: => Parser[U])(implicit combine: (T, U) => V): Parser[V] = new Parser[V] { + def apply(in: Input) = seq(Parser.this, q)((x, y) => combine(x,y))(in) + } */ + + /** A parser combinator for non-back-tracking sequential composition + * + *`p ~! q' succeeds if `p' succeeds and `q' succeeds on the input + * left over by `p'. In case of failure, no back-tracking is performed + * (in an earlier parser produced by the | combinator).
+ * + * @param q a parser that will be executed after `p' (this parser) succeeds + * @return a `Parser' that -- on success -- returns a `~' (like a Pair, but easier to pattern match on) + * that contains the result of `p' and that of `q'. + * The resulting parser fails if either `p' or `q' fails, this failure is fatal. + */ + def ~! [U](q: => Parser[U]): Parser[~[T, U]] = new Parser[~[T, U]] with OnceParser[~[T, U]] { + def apply(in: Input) = seq(Parser.this, commit(q))((x, y) => new ~(x,y))(in) + override def toString = "~!" + } + + /** A parser combinator for alternative composition + * + *`p | q' succeeds if `p' succeeds or `q' succeeds + * Note that `q' is only tried if `p's failure is non-fatal (i.e., back-tracking is + * allowed).
+ * + * @param q a parser that will be executed if `p' (this parser) fails (and allows back-tracking) + * @return a `Parser' that returns the result of the first parser to succeed (out of `p' and `q') + * The resulting parser succeeds if (and only if)`p ^^ f' succeeds if `p' succeeds; it returns `f' applied to the result of `p'.
+ * + * @param f a function that will be applied to this parser's result (see `map' in `ParseResult'). + * @return a parser that has the same behaviour as the current parser, but whose result is + * transformed by `f'. + */ + def ^^ [U](f: T => U): Parser[U] = new Parser[U] { + def apply(in: Input) = Parser.this(in).map(f) + override def toString = Parser.this.toString+"^^" + } + + def ^^^ [U](r: U): Parser[U] = ^^ (x => r) + + /** A parser combinator for partial function application + * + *`p ^? (f, error)' succeeds if `p' succeeds AND `f' is defined at the result of `p'; + * in that case, it returns `f' applied to the result of `p'. If `f' is not applicable, + * error(the result of `p') should explain why.
+ * + * @param f a partial function that will be applied to this parser's result + * (see `mapPartial' in `ParseResult'). + * @param error a function that takes the same argument as `f' and produces an error message + * to explain why `f' wasn't applicable + * @return a parser that succeeds if the current parser succeeds and `f' is applicable + * to the result. If so, the result will be transformed by `f'. + */ + def ^? [U](f: PartialFunction[T, U], error: T => String): Parser[U] = new Parser[U] { + def apply(in: Input) = Parser.this(in).mapPartial(f, error) + override def toString = Parser.this.toString+"^?" + } + + /** A parser combinator for partial function application + * + *`p ^? f' succeeds if `p' succeeds AND `f' is defined at the result of `p'; + * in that case, it returns `f' applied to the result of `p'.
+ * + * @param f a partial function that will be applied to this parser's result + * (see `mapPartial' in `ParseResult'). + * @return a parser that succeeds if the current parser succeeds and `f' is applicable + * to the result. If so, the result will be transformed by `f'. + */ + def ^? [U](f: PartialFunction[T, U]): Parser[U] = new Parser[U] { + def apply(in: Input) = Parser.this(in).mapPartial(f, result => "Constructor function not defined at "+result) + override def toString = Parser.this.toString+"^?" + } + + + /** A parser combinator that parameterises a subsequent parser with the result of this one + * + *+ * Use this combinator when a parser depends on the result of a previous parser. `p' should be + * a function that takes the result from the first parser and returns the second parser.
+ * + *`p into fq' (with `fq' typically `{x => q}') first applies `p', and then, if `p' successfully + * returned result `r', applies `fq(r)' to the rest of the input.
+ * + *From: G. Hutton. Higher-order functions for parsing. J. Funct. Program., 2(3):323--343, 1992.
+ * + * @param fq a function that, given the result from this parser, returns the second parser to be applied + * @return a parser that succeeds if this parser succeeds (with result `x') and if then `fq(x)' succeeds + */ + def into[U](fq: T => Parser[U]): Parser[U] = new Parser[U] { + def apply(in: Input) = Parser.this(in) match { + case Success(result, next) => fq(result)(next) + case ns: NoSuccess => ns + } + } + + // shortcuts for combinators: + + /** Returns into(fq) */ + def >>[U](fq: T => Parser[U])=into(fq) + + + /** Returns a parser that repeatedly parses what this parser parses + * + * @return rep(this) + */ + def * = rep(this) + + /** Returns a parser that repeatedly parses what this parser parses, interleaved with the `sep' parser. + * The `sep' parser specifies how the results parsed by this parser should be combined. + * + * @return chainl1(this, sep) + */ + def *[U >: T](sep: => Parser[(U, U) => U]) = chainl1(this, sep) + + // TODO: improve precedence? a ~ b*(",") = a ~ (b*(",")) should be true + + /** Returns a parser that repeatedly (at least once) parses what this parser parses. + * + * @return rep1(this) + */ + def + = rep1(this) + + /** Returns a parser that optionally parses what this parser parses. + * + * @return opt(this) + */ + def ? = opt(this) + } + + // TODO: can this implemented in ParseResult, like map? + /** A helper method for sequential composition of (unit-)parsers + */ + private def seq[T, U, V](p: => Input => ParseResult[T], q: => Input => ParseResult[U]) + (compose: (T, U) => V) + (in: Input): ParseResult[V] + = p(in) match { + case Success(x, next1) => q(next1) match { + case Success(y, next2) => Success(compose(x, y), next2) + case ns: NoSuccess => ns + } + case ns: NoSuccess => ns + } + + /** Wrap a parser so that its failures become errors (the | combinator will give up as soon as + * it encounters an error, on failure it simply tries the next alternative) + */ + def commit[T](p: => Parser[T]) = new Parser[T] { + def apply(in: Input) = p(in) match{ + case s @ Success(_, _) => s + case e @ Error(_, _) => e + case f @ Failure(msg, next) => Error(msg, next) + } + } + + /*trait ElemFun + case class EFCons(hd: Elem => ElemFun, tl: ElemFun) extends ElemFun + case class EFNil(res: Boolean) extends ElemFun*/ + + + /** A parser matching input elements that satisfy a given predicate + * + *elem(kind, p) succeeds if the input starts with an element `e' for which p(e) is true.
+ * + * @param kind The element kind, used for error messages + * @param p A predicate that determines which elements match. + * @return + */ + def elem(kind: String, p: Elem => Boolean) = new Parser[Elem] { + def apply(in: Input) = + if (p(in.first)) Success(in.first, in.rest) + else Failure(kind+" expected", in) + } + + /** A parser that matches only the given element `e' + * + *elem(e) succeeds if the input starts with an element `e'
+ * + * @param e the `Elem' that must be the next piece of input for the returned parser to succeed + * @return a `Parser' that succeeds if `e' is the next available input (and returns it). + */ + def elem(e: Elem): Parser[Elem] = new Parser[Elem] { + def apply(in: Input) = + if (in.first == e) Success(e, in.rest) + else Failure("`"+e+"' expected but " + in.first + " found", in) + } + + + /** A parser that matches only the given element `e' + *+ * The method is implicit so that elements can automatically be lifted to their parsers. + * For example, when parsing `Token's, Identifier("new") (which is a `Token') can be used directly, + * instead of first creating a `Parser' using accept(Identifier("new")).
+ * + * @param e the `Elem' that must be the next piece of input for the returned parser to succeed + * @return a `tParser' that succeeds if `e' is the next available input. + */ + implicit def accept(e: Elem): Parser[Elem] = new Parser[Elem] { + def apply(in: Input) = + if (in.first == e) Success(e, in.rest) + else Failure("`"+e+"' expected but " + in.first + " found", in) + } + + /** A parser that matches only the given list of element `es' + * + *accept(es) succeeds if the input subsequently provides the elements in the list `es'.
+ * + * @param es the list of expected elements + * @return a Parser that recognizes a specified list of elements + */ + def accept[ES <% List[Elem]](es: ES) = new Parser[List[Elem]] { + def apply(in0: Input) = { + var these: List[Elem] = es + var in = in0 + + while(!these.isEmpty && in.first == these.head) { + these = these.tail + in = in.rest + } + + if (these.isEmpty) Success(es: List[Elem], in) + else Failure("Expected: '"+these.head+"', found: '"+in.first+"'", in0) + } + } + + /** The parser that matches an element in the domain of the partial function `f' + *+ * If `f' is defined on the first element in the input, `f' is applied to it to produce + * this parser's result.
+ *
+ * Example: The parser accept("name", {case Identifier(n) => Name(n)})
+ * accepts an Identifier(n)
and returns a Name(n)
.
rep(p) repeatedly uses `p' to parse the input until `p' fails (the result is a List + * of the consecutive results of `p')
+ * + * @param p a `Parser' that is to be applied successively to the input + * @return A parser that returns a list of results produced by repeatedly applying `p' to the input. + */ + def rep[T](p: => Parser[T]): Parser[List[T]] = rep1(p) | success(List()) + + /** A parser generator for interleaved repetitions. + * + *repsep(p, q) repeatedly uses `p' interleaved with `q' to parse the input, until `p' fails. + * (The result is a `List' of the results of `p'.)
+ * + *Example: repsep(term, ",")
parses a comma-separated list of term's,
+ * yielding a list of these terms
rep1(p) repeatedly uses `p' to parse the input until `p' fails -- `p' must succeed at least + * once (the result is a `List' of the consecutive results of `p')
+ * + * @param p a `Parser' that is to be applied successively to the input + * @return A parser that returns a list of results produced by repeatedly applying `p' to the input + * (and that only succeeds if `p' matches at least once). + */ + def rep1[T](p: => Parser[T]): Parser[List[T]] = rep1(p, p) + + /** A parser generator for non-empty repetitions. + * + *rep1(f, p) first uses `f' (which must succeed) and then repeatedly uses `p' to + * parse the input until `p' fails + * (the result is a `List' of the consecutive results of `f' and `p')
+ * + * @param first a `Parser' that parses the first piece of input + * @param p a `Parser' that is to be applied successively to the rest of the input (if any) + * @return A parser that returns a list of results produced by first applying `f' and then + * repeatedly `p' to the input (it only succeeds if `f' matches). + */ + def rep1[T](first: => Parser[T], p: => Parser[T]): Parser[List[T]] = first ~ rep(p) ^^ { case ~(x, xs) => x :: xs } + + /* new Parser[List[T]] { + def apply(in0: Input) = { + val xs = new scala.collection.mutable.ListBuffer[T] + var in = in0 + + var res = first(in) + + while(res.successful) { + xs += res.get + in = res.next + res = p(in) + } + + if (!xs.isEmpty) Success(xs.toList, res.next) + else Failure("TODO", TODO) + } + }*/ + + /** A parser generator for a specified number of repetitions. + * + *repN(n, p) uses `p' exactly `n' time to parse the input + * (the result is a `List' of the `n' consecutive results of `p')
+ * + * @param p a `Parser' that is to be applied successively to the input + * @param n the exact number of times `p' must succeed + * @return A parser that returns a list of results produced by repeatedly applying `p' to the input + * (and that only succeeds if `p' matches exactly `n' times). + */ + def repN[T](n: Int, p: => Parser[T]): Parser[List[T]] = + if(n==0) success(Nil) else p ~ repN(n-1, p) ^^ { case ~(x, xs) => x :: xs } + + /** A parser generator for non-empty repetitions. + * + *rep1sep(first, p, q) starts by using `first', followed by repeatedly uses of `p' interleaved with `q' + * to parse the input, until `p' fails. `first' must succeed (the result is a `List' of the + * consecutive results of `first' and `p')
+ * + * @param first a `Parser' that is to be applied to the first element of input + * @param p a `Parser' that is to be applied successively to the input + * @param q a `Parser' that parses the elements that separate the elements parsed by `p' + * (interleaved with `q') + * @return A parser that returns a list of results produced by repeatedly applying `p' to the input + * (and that only succeeds if `p' matches at least once). + * The results of `p' are collected in a list. The results of `q' are discarded. + */ + def rep1sep[T](p: => Parser[T], q: => Parser[Any]): Parser[List[T]] = + p ~ (q ~ rep1sep(p, q) ^^ { case x ~ y => y } | success(List())) ^^ { case x ~ y => x :: y } + + /** A parser generator that, roughly, generalises the rep1sep generator so that `q', which parses the separator, + * produces a left-associative function that combines the elements it separates. + * + *From: J. Fokker. Functional parsers. In J. Jeuring and E. Meijer, editors, Advanced Functional Programming, volume 925 of Lecture Notes in Computer Science, pages 1--23. Springer, 1995.
+ * + * @param p a parser that parses the elements + * @param q a parser that parses the token(s) separating the elements, yielding a left-associative function that + * combines two elements into one + */ + def chainl1[T](p: => Parser[T], q: => Parser[(T, T) => T]): Parser[T] = + p ~ rep(q ~ p) ^^ {case x ~ xs => xs.foldLeft(x)((a, f_b) => f_b._1(a, f_b._2))} // ((a, {f, b}) => f(a, b)) + + /** A parser generator that, roughly, generalises the rep1sep generator so that `q', which parses the separator, + * produces a left-associative function that combines the elements it separates. + * + * @param first a parser that parses the first element + * @param p a parser that parses the subsequent elements + * @param q a parser that parses the token(s) separating the elements, yielding a left-associative function that + * combines two elements into one + */ + def chainl1[T, U](first: => Parser[T], p: => Parser[U], q: => Parser[(T, U) => T]): Parser[T] = + first ~ rep(q ~ p) ^^ {case x ~ xs => xs.foldLeft(x)((a, f_b) => f_b._1(a, f_b._2))} // ((a, {f, b}) => f(a, b)) + + /** A parser generator that generalises the rep1sep generator so that `q', which parses the separator, + * produces a right-associative function that combines the elements it separates. Additionally, + * The right-most (last) element and the left-most combinating function have to be supplied. + * + * rep1sep(p: Parser[T], q) corresponds to chainr1(p, q ^^ cons, cons, Nil) (where val cons = (x: T, y: List[T]) => x :: y) + * + * @param p a parser that parses the elements + * @param q a parser that parses the token(s) separating the elements, yielding a right-associative function that + * combines two elements into one + * @param combine the "last" (left-most) combination function to be applied + * @param first the "first" (right-most) element to be combined + */ + def chainr1[T, U](p: Parser[T], q: Parser[(T, U) => U], combine: (T, U) => U, first: U): Parser[U] = + p ~ rep(q ~ p) ^^ {case x ~ xs => + (new ~(combine, x) :: xs).foldRight(first)((f_a, b) => f_a._1(f_a._2, b))} // (({f, a}, b) => f(a, b)) + + /** A parser generator for optional sub-phrases. + * + *opt(p) is a parser that returns `Some(x)' if `p' returns `x' and `None' if `p' fails
+ * + * @param p A `Parser' that is tried on the input + * @return a `Parser' that always succeeds: either with the result provided by `p' or + * with the empty result + */ + def opt[T](p: => Parser[T]): Parser[Option[T]] = + p ^^ (x => Some(x)) | success(None) + + /** `positioned' decorates a parser's result with the start position of the input it consumed. + * + * @param p a `Parser' whose result conforms to `Positional'. + * @return A parser that has the same behaviour as `p', but which marks its result with the + * start position of the input it consumed, if it didn't already have a position. + */ + def positioned[T <: Positional](p: => Parser[T]): Parser[T] = new Parser[T] { + def apply(in: Input) = p(in) match { + case Success(t, in1) => Success(if (t.pos == NoPosition) t setPos in.pos else t, in1) + case ns: NoSuccess => ns + } + } + + case class ~[+a, +b](_1: a, _2: b) { + override def toString = "("+ _1 +" ~ "+ _2 +")" + } + + /** A function that always returns a given constant; useful as right-hand argument of ^^ + */ + + def const[T, U] (result: U): T => U = x => result + + /** A parser whose ~ combinator disallows back-tracking. + */ + trait OnceParser[+T] extends Parser[T] { + override def ~ [U](q: => Parser[U]): Parser[~[T, U]] = new Parser[~[T, U]] with OnceParser[~[T, U]] { + def apply(in: Input) = seq(OnceParser.this, commit(q))((x, y) => new ~(x, y))(in) + } + } +} diff --git a/src/library/scala/util/parsing/combinator1/lexical/Lexical.scala b/src/library/scala/util/parsing/combinator1/lexical/Lexical.scala new file mode 100644 index 0000000000..31ecdc629d --- /dev/null +++ b/src/library/scala/util/parsing/combinator1/lexical/Lexical.scala @@ -0,0 +1,41 @@ +/* __ *\ +** ________ ___ / / ___ Scala API ** +** / __/ __// _ | / / / _ | (c) 2006-2007, LAMP/EPFL ** +** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ ** +** /____/\___/_/ |_/____/_/ | | ** +** |/ ** +\* */ + +// $Id: Lexical.scala 12268 2007-07-11 13:45:53Z michelou $ + + +package scala.util.parsing.combinator1.lexical + +import scala.util.parsing.syntax._ +import scala.util.parsing.input.CharArrayReader.EofCh + +/**
+ * This component complements the Scanners
component with
+ * common operations for lexical parsers.
+ *
+ * {@see StdLexical} for a concrete implementation for a simple, Scala-like + * language. + *
+ * + * @author Martin Odersky, Adriaan Moors + */ +abstract class Lexical extends Scanners with Tokens { + + /** A character-parser that matches a letter (and returns it)*/ + def letter = elem("letter", _.isLetter) + + /** A character-parser that matches a digit (and returns it)*/ + def digit = elem("digit", _.isDigit) + + /** A character-parser that matches any character except the ones given in `cs' (and returns it)*/ + def chrExcept(cs: Char*) = elem("", ch => (cs forall (ch !=))) + + /** A character-parser that matches a white-space character (and returns it)*/ + def whitespaceChar = elem("space char", ch => ch <= ' ' && ch != EofCh) +} diff --git a/src/library/scala/util/parsing/combinator1/lexical/Scanners.scala b/src/library/scala/util/parsing/combinator1/lexical/Scanners.scala new file mode 100644 index 0000000000..af5c141267 --- /dev/null +++ b/src/library/scala/util/parsing/combinator1/lexical/Scanners.scala @@ -0,0 +1,75 @@ +/* __ *\ +** ________ ___ / / ___ Scala API ** +** / __/ __// _ | / / / _ | (c) 2006-2007, LAMP/EPFL ** +** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ ** +** /____/\___/_/ |_/____/_/ | | ** +** |/ ** +\* */ + +// $Id: Scanners.scala 12407 2007-07-25 02:33:18Z emir $ + + +package scala.util.parsing.combinator1.lexical + +import scala.util.parsing.syntax._ +import scala.util.parsing.input._ + +/**+ * This component provides core functionality for lexical parsers. + *
+ *+ * See its subclasses {@see Lexical} and -- most interestingly + * {@see StdLexical}, for more functionality. + *
+ * + * @requires token a parser that produces a token (from a stream of characters) + * @requires whitespace a unit-parser for white-space + * @provides Scanner essentially a parser that parses a stream of characters + * to produce `Token's, which are typically passed to a + * syntactical parser (which operates on `Token's, not on + * individual characters). + * + * @author Martin Odersky, Adriaan Moors + */ +trait Scanners extends Parsers { + type Elem = Char + type Token + + /** This token is produced by a scanner {@see Scanner} when scanning failed. */ + def errorToken(msg: String): Token + + /** a parser that produces a token (from a stream of characters) */ + def token: Parser[Token] + + /** a parser for white-space -- its result will be discarded */ + def whitespace: Parser[Any] + + /**
+ * Scanner
is essentially(*) a parser that produces `Token's
+ * from a stream of characters. The tokens it produces are typically
+ * passed to parsers in TokenParsers
.
+ *
+ * Note: (*) Scanner
is really a `Reader' of `Token's
+ *
+ * This component provides a standard lexical parser for a simple, Scala-like language. + * It parses keywords and identifiers, numeric literals (integers), strings, and delimiters. + *
+ *+ * To distinguish between identifiers and keywords, it uses a set of reserved identifiers: + * every string contained in `reserved' is returned as a keyword token. + * (Note that "=>" is hard-coded as a keyword.) + * Additionally, the kinds of delimiters can be specified by the `delimiters' set. + *
+ *+ * Usually this component is used to break character-based input into bigger tokens, + * which are then passed to a token-parser {@see TokenParsers}. + *
+ * + * @author Martin Odersky, Iulian Dragos, Adriaan Moors + */ +class StdLexical extends Lexical with StdTokens { + // see `token' in `Scanners' + def token: Parser[Token] = + ( letter ~ rep( letter | digit ) ^^ { case first ~ rest => processIdent(first :: rest mkString "") } + | digit ~ rep( digit ) ^^ { case first ~ rest => NumericLit(first :: rest mkString "") } + | '\'' ~ rep( chrExcept('\'', '\n', EofCh) ) ~ '\'' ^^ { case _ ~ chars ~ _ => StringLit(chars mkString "") } + | '\"' ~ rep( chrExcept('\"', '\n', EofCh) ) ~ '\"' ^^ { case _ ~ chars ~ _ => StringLit(chars mkString "") } + | EofCh ^^ const(EOF) + | '\'' ~> failure("unclosed string literal") + | '\"' ~> failure("unclosed string literal") + | delim + | failure("illegal character") + ) + + // see `whitespace in `Scanners' + def whitespace: Parser[Any] = rep( + whitespaceChar + | '/' ~ '*' ~ comment + | '/' ~ '/' ~ rep( chrExcept(EofCh, '\n') ) + | '/' ~ '*' ~ failure("unclosed comment") + ) + + protected def comment: Parser[Any] = ( + '*' ~ '/' ^^ { case _ => ' ' } + | chrExcept(EofCh) ~ comment + ) + + /** The set of reserved identifiers: these will be returned as `Keyword's */ + val reserved = new HashSet[String] + + /** The set of delimiters (ordering does not matter) */ + val delimiters = new HashSet[String] + + protected def processIdent(name: String) = + if (reserved contains name) Keyword(name) else Identifier(name) + + private var _delim: Parser[Token] = null + protected def delim: Parser[Token] = { + if(_delim eq null) { // construct parser for delimiters by |'ing together the parsers for the individual delimiters, + // starting with the longest one (hence the sort + reverse) -- otherwise a delimiter D will never be matched if + // there is another delimiter that is a prefix of D + def parseDelim(s: String): Parser[Token] = accept(s.toList) ^^ { x => Keyword(s) } + + val d = new Array[String](delimiters.size) + delimiters.copyToArray(d,0) + scala.util.Sorting.quickSort(d) + _delim = d.toList.reverse.map(parseDelim).reduceRight[Parser[Token]](_ | _) // no offence :-) + } + + _delim + } + + private def lift[T](f: String => T)(xs: List[Char]): T = f(xs.mkString("", "", "")) + + private def lift2[T](f: String => T)(p: ~[Char, List[Char]]): T = lift(f)(p._1 :: p._2) +} diff --git a/src/library/scala/util/parsing/combinator1/syntactical/StandardTokenParsers.scala b/src/library/scala/util/parsing/combinator1/syntactical/StandardTokenParsers.scala new file mode 100644 index 0000000000..68d0d07c39 --- /dev/null +++ b/src/library/scala/util/parsing/combinator1/syntactical/StandardTokenParsers.scala @@ -0,0 +1,24 @@ +/* __ *\ +** ________ ___ / / ___ Scala API ** +** / __/ __// _ | / / / _ | (c) 2006-2007, LAMP/EPFL ** +** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ ** +** /____/\___/_/ |_/____/_/ | | ** +** |/ ** +\* */ + +// $Id: StdTokenParsers.scala 12242 2007-07-09 09:43:09Z michelou $ + + +package scala.util.parsing.combinator1.syntactical + +import scala.util.parsing.syntax._ +import scala.util.parsing.combinator1.lexical.StdLexical + +/** This component provides primitive parsers for the standard tokens defined in `StdTokens'. +* +* @author Martin Odersky, Adriaan Moors + */ +class StandardTokenParsers extends StdTokenParsers { + type Tokens = StdTokens + val lexical = new StdLexical +} diff --git a/src/library/scala/util/parsing/combinator1/syntactical/StdTokenParsers.scala b/src/library/scala/util/parsing/combinator1/syntactical/StdTokenParsers.scala new file mode 100644 index 0000000000..e344f988f8 --- /dev/null +++ b/src/library/scala/util/parsing/combinator1/syntactical/StdTokenParsers.scala @@ -0,0 +1,44 @@ +/* __ *\ +** ________ ___ / / ___ Scala API ** +** / __/ __// _ | / / / _ | (c) 2006-2007, LAMP/EPFL ** +** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ ** +** /____/\___/_/ |_/____/_/ | | ** +** |/ ** +\* */ + +// $Id: StdTokenParsers.scala 12242 2007-07-09 09:43:09Z michelou $ + + +package scala.util.parsing.combinator1.syntactical + +import scala.util.parsing.syntax._ + +/** This component provides primitive parsers for the standard tokens defined in `StdTokens'. +* +* @author Martin Odersky, Adriaan Moors + */ +trait StdTokenParsers extends TokenParsers { + type Tokens <: StdTokens + import lexical.{Keyword, NumericLit, StringLit, Identifier} + + /** A parser which matches a single keyword token. + * + * @param chars The character string making up the matched keyword. + * @return a `Parser' that matches the given string + */ + implicit def keyword(chars: String): Parser[String] = accept(Keyword(chars)) ^^ (_.chars) + + /** A parser which matches a numeric literal */ + def numericLit: Parser[String] = + elem("number", _.isInstanceOf[NumericLit]) ^^ (_.chars) + + /** A parser which matches a string literal */ + def stringLit: Parser[String] = + elem("string literal", _.isInstanceOf[StringLit]) ^^ (_.chars) + + /** A parser which matches an identifier */ + def ident: Parser[String] = + elem("identifier", _.isInstanceOf[Identifier]) ^^ (_.chars) +} + + diff --git a/src/library/scala/util/parsing/combinator1/syntactical/TokenParsers.scala b/src/library/scala/util/parsing/combinator1/syntactical/TokenParsers.scala new file mode 100644 index 0000000000..d4f8a9dfc8 --- /dev/null +++ b/src/library/scala/util/parsing/combinator1/syntactical/TokenParsers.scala @@ -0,0 +1,64 @@ +/* __ *\ +** ________ ___ / / ___ Scala API ** +** / __/ __// _ | / / / _ | (c) 2006-2007, LAMP/EPFL ** +** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ ** +** /____/\___/_/ |_/____/_/ | | ** +** |/ ** +\* */ + +// $Id: TokenParsers.scala 12242 2007-07-09 09:43:09Z michelou $ + + +package scala.util.parsing.combinator1.syntactical + +/**+ * This is the core component for token-based parsers. + *
+ *+ * @requires lexical a component providing the tokens consumed by the + * parsers in this component. + *
+ * + * @author Martin Odersky, Adriaan Moors + */ +trait TokenParsers extends Parsers { + /** Tokens is the abstract type of the `Token's consumed by the parsers in this component*/ + type Tokens <: scala.util.parsing.syntax.Tokens + + /** lexical is the component responsible for consuming some basic kind of + * input (usually character-based) and turning it into the tokens + * understood by these parsers. + */ + val lexical: Tokens + + /** The input-type for these parsers*/ + type Elem = lexical.Token + + /**+ * A parser generator delimiting whole phrases (i.e. programs). + *
+ *
+ * phrase(p)
succeeds if p
succeeds and
+ * no input is left over after p
.
+ *
p
consumed all the input.
+ */
+ def phrase[t](p: Parser[t]) = new Parser[t] {
+ def apply(in: Input) = p(in) match {
+ case s @ Success(out, in1) if in1.atEnd => s
+ case s @ Success(out, in1) => Failure("end of input expected", in1)
+ case f @ Failure(_, in1) => in1.first match {
+ case lexical.ErrorToken(msg) => Failure(msg, in1)
+ case lexical.EOF => Failure("unexpected end of input", in1)
+ case t => Failure("unexpected token "+t, in1)
+ }
+ case f => f
+ }
+ }
+}
+
+
diff --git a/src/library/scala/util/parsing/combinator1/testing/Tester.scala b/src/library/scala/util/parsing/combinator1/testing/Tester.scala
new file mode 100644
index 0000000000..e2f5d61e53
--- /dev/null
+++ b/src/library/scala/util/parsing/combinator1/testing/Tester.scala
@@ -0,0 +1,45 @@
+/* __ *\
+** ________ ___ / / ___ Scala API **
+** / __/ __// _ | / / / _ | (c) 2006-2007, LAMP/EPFL **
+** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
+** /____/\___/_/ |_/____/_/ | | **
+** |/ **
+\* */
+
+package scala.util.parsing.combinator1.testing
+
+import scala.util.parsing.combinator1.lexical.Lexical
+import scala.util.parsing.combinator1.syntactical.TokenParsers
+
+/** + * Facilitates testing a given parser on various input strings. + *
+ *+ * Example use: + *
+ * val syntactic = new MyParsers+ *
+ * and + *
+ * val parser = syntactic.term+ *
+ * (if MyParsers extends TokenParsers with a parser called `term') + *
+ * + * @author Martin Odersky, Adriaan Moors + */ +abstract class Tester { + + val syntactic: TokenParsers { val lexical: Lexical } + val parser: syntactic.Parser[Any] + + + /** Scans a String (using a `syntactic.lexical.Scanner'), parses it + * usingphrase(parser)
, and prints the input and the
+ * parsed result to the console.
+ */
+ def test(in: String) {
+ Console.println("\nin : "+in)
+ Console.println(syntactic.phrase[Any](parser)(new syntactic.lexical.Scanner(in)))
+ }
+}
--
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