/* Title: Pure/PIDE/yxml.scala
Author: Makarius
Efficient text representation of XML trees. Suitable for direct
inlining into plain text.
*/
package isabelle
import scala.collection.mutable
object YXML {
/* chunk markers */
val X_byte: Byte = 5
val Y_byte: Byte = 6
val X = X_byte.toChar
val Y = Y_byte.toChar
val is_X: Char => Boolean = _ == X
val is_Y: Char => Boolean = _ == Y
val X_string: String = X.toString
val Y_string: String = Y.toString
val XY_string: String = X_string + Y_string
val XYX_string: String = XY_string + X_string
def detect(s: String): Boolean = s.exists(c => c == X || c == Y)
def detect_elem(s: String): Boolean = s.startsWith(XY_string)
/* string representation */
trait Output extends XML.Traversal {
def byte(b: Byte): Unit
def string(s: String): Unit
// XML.Traversal
override def text(s: String): Unit = string(s)
override def elem(markup: Markup, end: Boolean = false): Unit = {
byte(X_byte)
byte(Y_byte)
string(markup.name)
for ((a, b) <- markup.properties) {
byte(Y_byte)
string(a)
byte('='.toByte)
string(b)
}
byte(X_byte)
if (end) end_elem(markup.name)
}
override def end_elem(name: String): Unit = {
byte(X_byte)
byte(Y_byte)
byte(X_byte)
}
}
class Output_String(builder: StringBuilder, recode: String => String = identity) extends Output {
override def byte(b: Byte): Unit = { builder += b.toChar }
override def string(s: String): Unit = { builder ++= recode(s) }
def result(ts: List[XML.Tree]): String = { traverse(ts); builder.toString }
}
class Output_Bytes(builder: Bytes.Builder, recode: String => String = identity) extends Output {
override def byte(b: Byte): Unit = { builder += b }
override def string(s: String): Unit = { builder += recode(s) }
}
def string_of_body(body: XML.Body, recode: String => String = identity): String =
new Output_String(new StringBuilder, recode = recode).result(body)
def string_of_tree(tree: XML.Tree, recode: String => String = identity): String =
string_of_body(List(tree), recode = recode)
def bytes_of_body(body: XML.Body, recode: String => String = identity): Bytes =
Bytes.Builder.use()(builder => new Output_Bytes(builder, recode = recode).traverse(body))
def bytes_of_tree(tree: XML.Tree, recode: String => String = identity): Bytes =
bytes_of_body(List(tree), recode = recode)
/* parsing */
private def err(msg: String) = error("Malformed YXML: " + msg)
private def err_attribute() = err("bad attribute")
private def err_element() = err("bad element")
private def err_unbalanced(name: String) =
if (name == "") err("unbalanced element")
else err("unbalanced element " + quote(name))
private def parse_attrib(source: CharSequence): (String, String) =
Properties.Eq.unapply(source.toString) getOrElse err_attribute()
def parse_body(source: CharSequence, cache: XML.Cache = XML.Cache.none): XML.Body = {
/* stack operations */
def buffer(): mutable.ListBuffer[XML.Tree] = new mutable.ListBuffer[XML.Tree]
var stack: List[(Markup, mutable.ListBuffer[XML.Tree])] = List((Markup.Empty, buffer()))
def add(x: XML.Tree): Unit =
(stack: @unchecked) match { case (_, body) :: _ => body += x }
def push(name: String, atts: XML.Attributes): Unit =
if (name == "") err_element()
else stack = (cache.markup(Markup(name, atts)), buffer()) :: stack
def pop(): Unit =
(stack: @unchecked) match {
case (Markup.Empty, _) :: _ => err_unbalanced("")
case (markup, body) :: pending =>
stack = pending
add(cache.tree0(XML.Elem(markup, body.toList)))
}
/* parse chunks */
for (chunk <- Library.separated_chunks(is_X, source) if chunk.length != 0) {
if (chunk.length == 1 && chunk.charAt(0) == Y) pop()
else {
Library.separated_chunks(is_Y, chunk).toList match {
case ch :: name :: atts if ch.length == 0 =>
push(name.toString, atts.map(parse_attrib))
case txts => for (txt <- txts) add(cache.tree0(XML.Text(cache.string(txt.toString))))
}
}
}
(stack: @unchecked) match {
case List((Markup.Empty, body)) => body.toList
case (Markup(name, _), _) :: _ => err_unbalanced(name)
}
}
def parse(source: CharSequence, cache: XML.Cache = XML.Cache.none): XML.Tree =
parse_body(source, cache = cache) match {
case List(result) => result
case Nil => XML.no_text
case _ => err("multiple XML trees")
}
def parse_elem(source: CharSequence, cache: XML.Cache = XML.Cache.none): XML.Tree =
parse_body(source, cache = cache) match {
case List(elem: XML.Elem) => elem
case _ => err("single XML element expected")
}
/* failsafe parsing */
private def markup_broken(source: CharSequence) =
XML.Elem(Markup.Broken, List(XML.Text(source.toString)))
def parse_body_failsafe(source: CharSequence, cache: XML.Cache = XML.Cache.none): XML.Body = {
try { parse_body(source, cache = cache) }
catch { case ERROR(_) => List(markup_broken(source)) }
}
def parse_failsafe(source: CharSequence, cache: XML.Cache = XML.Cache.none): XML.Tree = {
try { parse(source, cache = cache) }
catch { case ERROR(_) => markup_broken(source) }
}
}