laika.internal.parse.markup.DefaultEscapedTextParsers.scala Maven / Gradle / Ivy

/*
 * Copyright 2012-2020 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package laika.internal.parse.markup

import laika.parse.Parser
import laika.parse.syntax.*
import laika.parse.markup.{ EscapedTextParsers, InlineParsers }
import laika.parse.text.{ DelimitedText, PrefixedParser, TextParsers }

/** Default implementation for parsing escape sequences.
  *
  * @author Jens Halm
  */
private[internal] trait DefaultEscapedTextParsers extends EscapedTextParsers {

  /** Parses a single escape character.
    * In the default implementation any character can be escaped.
    * Sub-traits may override this parser to restrict the number of escapable characters.
    */
  lazy val escapedChar: Parser[String] = TextParsers.oneChar

  lazy val escapeSequence: PrefixedParser[String] = "\\" ~> escapedChar

  /** Adds support for escape sequences to the specified text parser.
    *
    * @param p the parser to add support for escape sequences to
    * @return a parser for a text span that supports escape sequences
    */
  def escapedText(p: DelimitedText): Parser[String] = InlineParsers.text(p).embed(escapeSequence)

  /** Parses a span of text until one of the specified characters is seen
    * (unless it is escaped),
    * while also processing escaped characters, but no other nested
    *  spans. The final character is not included in the result.
    */
  def escapedUntil(char: Char, chars: Char*): Parser[String] = escapedText(
    TextParsers.delimitedBy(char, chars: _*).nonEmpty
  )

}