sjsonnew.support.scalajson.unsafe.JsonPrinter.scala Maven / Gradle / Ivy
/*
* Copyright (C) 2009-2011 Mathias Doenitz
* Adapted and extended in 2016 by Eugene Yokota
*
* 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 sjsonnew
package support.scalajson.unsafe
import annotation.tailrec
import java.lang.{Appendable, StringBuilder => JStringBuilder}
import shaded.scalajson.ast.unsafe._
/**
* A JsonPrinter serializes a JSON AST to a String.
*/
trait JsonPrinter extends (JValue => String) {
def apply(x: JValue): String = apply(x, None)
def apply(x: JValue,
jsonpCallback: Option[String] = None,
sb: JStringBuilder = new JStringBuilder(256)): String = {
jsonpCallback match {
case Some(callback) =>
sb.append(callback).append('(')
print(x, sb)
sb.append(')')
case None => print(x, sb)
}
sb.toString
}
def print(x: JValue, sb: Appendable): Unit
protected def printLeaf(x: JValue, sb: Appendable): Unit = {
x match {
case JNull => sb.append("null")
case JTrue => sb.append("true")
case JFalse => sb.append("false")
case JNumber(x) => sb.append(x)
case JString(x) => printString(x, sb)
case _ => throw new IllegalStateException
}
}
protected def printString(s: String, sb: Appendable): Unit = {
import JsonPrinter._
@tailrec def firstToBeEncoded(ix: Int = 0): Int =
if (ix == s.length) -1 else if (requiresEncoding(s.charAt(ix))) ix else firstToBeEncoded(ix + 1)
sb.append('"')
firstToBeEncoded() match {
case -1 => sb.append(s)
case first =>
sb.append(s, 0, first)
@tailrec def append(ix: Int): Unit =
if (ix < s.length) {
s.charAt(ix) match {
case c if !requiresEncoding(c) => sb.append(c)
case '"' => sb.append("\\\"")
case '\\' => sb.append("\\\\")
case '\b' => sb.append("\\b")
case '\f' => sb.append("\\f")
case '\n' => sb.append("\\n")
case '\r' => sb.append("\\r")
case '\t' => sb.append("\\t")
case x if x <= 0xF => sb.append("\\u000").append(Integer.toHexString(x))
case x if x <= 0xFF => sb.append("\\u00").append(Integer.toHexString(x))
case x if x <= 0xFFF => sb.append("\\u0").append(Integer.toHexString(x))
case x => sb.append("\\u").append(Integer.toHexString(x))
}
append(ix + 1)
}
append(first)
}
sb.append('"')
}
protected def printArray[A](iterable: Array[A], printSeparator: => Unit)(f: A => Unit): Unit = {
var first = true
iterable.foreach { a =>
if (first) first = false else printSeparator
f(a)
}
}
}
object JsonPrinter {
def requiresEncoding(c: Char): Boolean =
// from RFC 4627
// unescaped = %x20-21 / %x23-5B / %x5D-10FFFF
c match {
case '"' => true
case '\\' => true
case c => c < 0x20
}
}