Created
November 3, 2010 09:00
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ParserConbinatorを使って、Wikiエンジンを書いてみる
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| import scala.util.parsing.combinator.Parsers | |
| import scala.util.parsing.input.CharSequenceReader | |
| class Document | |
| class Inline extends Document | |
| case class Text(s:String) extends Inline | |
| case class Strong(t:Text) extends Inline | |
| case class Line(l:List[Inline]) extends Document | |
| case class Headline(t:List[Inline]) extends Document | |
| case class Paragraph(p:List[Document]) extends Document | |
| case class Sentences(s:List[Document]) extends Document | |
| object WikiParser extends Parsers{ | |
| type Elem = Char | |
| lazy val ASTRISK = elem('*') | |
| lazy val QUOT = elem('"') | |
| lazy val LF = elem('\n') | |
| lazy val TAB = elem('\t') | |
| lazy val EOF = elem("EOF", _ == CharSequenceReader.EofCh) | |
| lazy val char:Parser[Char] = elem("ANY", c => c != CharSequenceReader.EofCh) | |
| def sentences:Parser[Sentences] = rep1(paragraph | headline) ~ EOF ^^ {xs => Sentences(xs._1)} | |
| def paragraph:Parser[Paragraph] = rep1(line) ~ rep(LF) ^^ {xs => Paragraph(xs._1) } | |
| def headline:Parser[Headline] = ASTRISK ~ rep1(text | inline) ~ LF ^^ {xs => Headline(xs._1._2) } | |
| def line: Parser[Line] = rep1(text | inline) ~ LF ^^ {xs => Line(xs._1)} | |
| def inline:Parser[Inline] = strong | |
| def strong:Parser[Strong] = QUOT ~ text ~ QUOT ^^ {xs => Strong(xs._1._2)} | |
| def text: Parser[Text] = rep1(not(LF) ~> not(QUOT) ~> not(ASTRISK) ~> char) ^^ {cs => Text(cs.mkString)} | |
| } | |
| object HTMLTransrator { | |
| def parse(doc:Document):String = { | |
| doc match { | |
| case Text(s) => s | |
| case Strong(t) => "<strong>" + parse(t) + "</strong>" | |
| case Headline(l) => "<h1>" + l.map( t => parse(t)).mkString + "</h1>" | |
| case Line(l) => l.map( t => parse(t)).mkString + "<br />" | |
| case Paragraph(p) => "<p>" + p.map(xs => parse(xs)).mkString + "</p>" | |
| case Sentences(s) => "<html>" + s.map(xs => parse(xs)).mkString + "</html>" | |
| } | |
| } | |
| } | |
| WikiParser.line(new CharSequenceReader("I \"love\" Scala !\n")) | |
| val ast = WikiParser.sentences(new CharSequenceReader("*Title\nHello\nWorld\n\nI \"love\" Scala !\n")).get | |
| HTMLTransrator.parse(ast) |
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