json_2.11.3.0.0-M1.source-code.ByteParser.scala Maven / Gradle / Ivy
package ujson
import java.io.StringWriter
import upickle.core.{Abort, AbortException, ObjArrVisitor, ObjVisitor, Visitor}
import java.nio.charset.Charset
import scala.annotation.{switch, tailrec}
/**
* A specialized JSON parse that can parse Bytes (Chars or Bytes), sending
* method calls to the given [[upickle.core.Visitor]].
*
* Generally has a lot of tricks for performance: e.g. having duplicate
* implementations for nested v.s. top-level parsing, using an `ByteBuilder`
* to construct the `CharSequences` that `visitString` requires, etc.
*/
abstract class ByteParser[J] extends upickle.core.BufferingByteParser{
private[this] val elemOps = upickle.core.ByteOps
private[this] val outputBuilder = new upickle.core.ByteBuilder()
def requestUntilOrThrow(i: Int) = {
if (requestUntil(i)) throw new IncompleteParseException("exhausted input")
}
override def getByteSafe(i: Int): Byte = {
requestUntilOrThrow(i)
getByteUnsafe(i)
}
/**
* Return true iff 'i' is at or beyond the end of the input (EOF).
*/
protected[this] def atEof(i: Int) = requestUntil(i)
/**
* Should be called when parsing is finished.
*/
protected[this] def close(): Unit
/**
* Valid parser states.
*/
@inline private[this] final val ARRBEG = 6
@inline private[this] final val OBJBEG = 7
@inline private[this] final val DATA = 1
@inline private[this] final val KEY = 2
@inline private[this] final val COLON = 3
@inline private[this] final val ARREND = 4
@inline private[this] final val OBJEND = 5
/**
* Parse the JSON document into a single JSON value.
*
* The parser considers documents like '333', 'true', and '"foo"' to be
* valid, as well as more traditional documents like [1,2,3,4,5]. However,
* multiple top-level objects are not allowed.
*/
final def parse(facade: Visitor[_, J]): J = {
val (value, i) = parseTopLevel(0, facade)
var j = i
while (!atEof(j)) {
(getByteSafe(j): @switch) match {
case '\n' | ' ' | '\t' | '\r' => j += 1
case _ => die(j, "expected whitespace or eof")
}
}
if (!atEof(j)) die(j, "expected eof")
close()
value
}
/**
* Used to generate error messages with character info and offsets.
*/
protected[this] def die(i: Int, msg: String): Nothing = {
val out = new upickle.core.ByteBuilder()
upickle.core.RenderUtils.escapeByte(
new upickle.core.CharBuilder(),
out,
new ArrayCharSequence(Array(elemOps.toInt(getByteSafe(i)).toChar)),
unicode = false,
true
)
val s = "%s got %s" format (msg, out.makeString())
throw ParseException(s, i)
}
/**
* Parse the given number, and add it to the given context.
*
* We don't actually instantiate a number here, but rather pass the
* string of for future use. Facades can choose to be lazy and just
* store the string. This ends up being way faster and has the nice
* side-effect that we know exactly how the user represented the
* number.
*/
protected[this] final def parseNum(i: Int, ctxt: ObjArrVisitor[Any, J], facade: Visitor[_, J]): Int = {
var j = i
var c = getByteSafe(j)
var decIndex = -1
var expIndex = -1
if (c == '-') {
j += 1
c = getByteSafe(j)
}
if (c == '0') {
j += 1
c = getByteSafe(j)
} else {
val j0 = j
while (elemOps.within('0', c, '9')) {
j += 1;
c = getByteSafe(j)
}
if (j == j0) die(i, "expected digit")
}
if (c == '.') {
decIndex = j - i
j += 1
c = getByteSafe(j)
val j0 = j
while (elemOps.within('0', c, '9')) {
j += 1
c = getByteSafe(j)
}
if (j0 == j) die(i, "expected digit")
}
if (c == 'e' || c == 'E') {
expIndex = j - i
j += 1
c = getByteSafe(j)
if (c == '+' || c == '-') {
j += 1
c = getByteSafe(j)
}
val j0 = j
while (elemOps.within('0', c, '9')) {
j += 1
c = getByteSafe(j)
}
if (j0 == j) die(i, "expected digit")
}
ctxt.visitValue(visitFloat64StringPartsWithWrapper(facade, decIndex, expIndex, i, j), i)
j
}
def visitFloat64StringPartsWithWrapper(facade: Visitor[_, J],
decIndex: Int,
expIndex: Int,
i: Int,
j: Int) = {
facade.visitFloat64StringParts(
unsafeCharSeqForRange(i, j - i),
decIndex,
expIndex,
i
)
}
/**
* Parse the given number, and add it to the given context.
*
* This method is a bit slower than parseNum() because it has to be
* sure it doesn't run off the end of the input.
*
* Normally (when operating in rparse in the context of an outer
* array or object) we don't need to worry about this and can just
* grab characters, because if we run out of characters that would
* indicate bad input. This is for cases where the number could
* possibly be followed by a valid EOF.
*
* This method has all the same caveats as the previous method.
*/
protected[this] final def parseNumTopLevel(i: Int, facade: Visitor[_, J]): (J, Int) = {
var j = i
var c = getByteSafe(j)
var decIndex = -1
var expIndex = -1
if (c == '-') {
// any valid input will require at least one digit after -
j += 1
c = getByteSafe(j)
}
if (c == '0') {
j += 1
if (atEof(j)) {
return (visitFloat64StringPartsWithWrapper(facade, decIndex, expIndex, i, j), j)
}
c = getByteSafe(j)
} else {
val j0 = j
while (elemOps.within('0', c, '9')) {
j += 1
if (atEof(j)) {
return (visitFloat64StringPartsWithWrapper(facade, decIndex, expIndex, i, j), j)
}
c = getByteSafe(j)
}
if (j0 == j) die(i, "expected digit")
}
if (c == '.') {
// any valid input will require at least one digit after .
decIndex = j - i
j += 1
c = getByteSafe(j)
val j0 = j
while (elemOps.within('0', c, '9')) {
j += 1
if (atEof(j)) {
return (visitFloat64StringPartsWithWrapper(facade, decIndex, expIndex, i, j), j)
}
c = getByteSafe(j)
}
if(j0 == j) die(i, "expected digit")
}
if (c == 'e' || c == 'E') {
// any valid input will require at least one digit after e, e+, etc
expIndex = j - i
j += 1
c = getByteSafe(j)
if (c == '+' || c == '-') {
j += 1
c = getByteSafe(j)
}
val j0 = j
while (elemOps.within('0', c, '9')) {
j += 1
if (atEof(j)) {
return (visitFloat64StringPartsWithWrapper(facade, decIndex, expIndex, i, j), j)
}
c = getByteSafe(j)
}
if (j0 == j) die(i, "expected digit")
}
(visitFloat64StringPartsWithWrapper(facade, decIndex, expIndex, i, j), j)
}
/**
* Generate a Char from the hex digits of "\u1234" (i.e. "1234").
*
* NOTE: This is only capable of generating characters from the basic plane.
* This is why it can only return Char instead of Int.
*/
protected[this] final def descape(i: Int): Char = {
import upickle.core.RenderUtils.hex
var x = 0
x = (x << 4) | hex(getByteSafe(i+2).toInt)
x = (x << 4) | hex(getByteSafe(i+3).toInt)
x = (x << 4) | hex(getByteSafe(i+4).toInt)
x = (x << 4) | hex(getByteSafe(i+5).toInt)
x.toChar
}
/**
* Parse the JSON constant "true".
*
* Note that this method assumes that the first character has already been checked.
*/
protected[this] final def parseTrue(i: Int, facade: Visitor[_, J]): J = {
requestUntilOrThrow(i + 3)
if (getByteUnsafe(i + 1) == 'r' && getByteUnsafe(i + 2) == 'u' && getByteUnsafe(i + 3) == 'e') {
facade.visitTrue(i)
} else {
die(i, "expected true")
}
}
/**
* Parse the JSON constant "false".
*
* Note that this method assumes that the first character has already been checked.
*/
protected[this] final def parseFalse(i: Int, facade: Visitor[_, J]): J = {
requestUntilOrThrow(i + 4)
if (getByteUnsafe(i + 1) == 'a' && getByteUnsafe(i + 2) == 'l' && getByteUnsafe(i + 3) == 's' && getByteUnsafe(i + 4) == 'e') {
facade.visitFalse(i)
} else {
die(i, "expected false")
}
}
/**
* Parse the JSON constant "null".
*
* Note that this method assumes that the first character has already been checked.
*/
protected[this] final def parseNull(i: Int, facade: Visitor[_, J]): J = {
requestUntilOrThrow(i + 3)
if (getByteUnsafe(i + 1) == 'u' && getByteUnsafe(i + 2) == 'l' && getByteUnsafe(i + 3) == 'l') {
facade.visitNull(i)
} else {
die(i, "expected null")
}
}
protected[this] final def parseTopLevel(i: Int, facade: Visitor[_, J]): (J, Int) = {
try parseTopLevel0(i, facade)
catch reject(i)
}
/**
* Parse and return the next JSON value and the position beyond it.
*/
@tailrec
protected[this] final def parseTopLevel0(i: Int, facade: Visitor[_, J]): (J, Int) = {
(getByteSafe(i): @switch) match {
// ignore whitespace
case ' ' | '\t' | 'r' => parseTopLevel0(i + 1, facade)
case '\n' => parseTopLevel0(i + 1, facade)
// if we have a recursive top-level structure, we'll delegate the parsing
// duties to our good friend rparse().
case '[' => parseNested(ARRBEG, i + 1, facade.visitArray(-1, i), Nil)
case '{' => parseNested(OBJBEG, i + 1, facade.visitObject(-1, true, i), Nil)
// we have a single top-level number
case '-' | '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' => parseNumTopLevel(i, facade)
// we have a single top-level string
case '"' => parseStringTopLevel(i, facade)
// we have a single top-level constant
case 't' => (parseTrue(i, facade), i + 4)
case 'f' => (parseFalse(i, facade), i + 5)
case 'n' => (parseNull(i, facade), i + 4)
// invalid
case _ => die(i, "expected json value")
}
}
def reject(j: Int): PartialFunction[Throwable, Nothing] = {
case e: Abort =>
throw new AbortException(e.msg, j, -1, -1, e)
}
/**
* Tail-recursive parsing method to do the bulk of JSON parsing.
*
* This single method manages parser states, data, etc. Except for
* parsing non-recursive values (like strings, numbers, and
* constants) all important work happens in this loop (or in methods
* it calls, like reset()).
*
* Currently the code is optimized to make use of switch
* statements. Future work should consider whether this is better or
* worse than manually constructed if/else statements or something
* else. Also, it may be possible to reorder some cases for speed
* improvements.
*
* @param j index/position in the source json
* @param path the json path in the tree
*/
@tailrec
protected[this] final def parseNested(state: Int,
i: Int,
stackHead: ObjArrVisitor[_, J],
stackTail: List[ObjArrVisitor[_, J]]) : (J, Int) = {
(getByteSafe(i): @switch) match{
case ' ' | '\t' | '\r' | '\n' =>
parseNested(state, i + 1, stackHead, stackTail)
case '"' =>
state match{
case KEY | OBJBEG =>
val nextJ = try parseStringKey(i, stackHead) catch reject(i)
parseNested(COLON, nextJ, stackHead, stackTail)
case DATA | ARRBEG =>
val nextJ = try parseStringValue(i, stackHead) catch reject(i)
parseNested(collectionEndFor(stackHead), nextJ, stackHead, stackTail)
case _ => dieWithFailureMessage(i, state)
}
case ':' =>
// we are in an object just after a key, expecting to see a colon.
state match{
case COLON => parseNested(DATA, i + 1, stackHead, stackTail)
case _ => dieWithFailureMessage(i, state)
}
case '[' =>
failIfNotData(state, i)
val ctx =
try stackHead.subVisitor.asInstanceOf[Visitor[_, J]].visitArray(-1, i)
catch reject(i)
parseNested(ARRBEG, i + 1, ctx, stackHead :: stackTail)
case '{' =>
failIfNotData(state, i)
val ctx =
try stackHead.subVisitor.asInstanceOf[Visitor[_, J]].visitObject(-1, true, i)
catch reject(i)
parseNested(OBJBEG, i + 1, ctx, stackHead :: stackTail)
case '-' | '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' =>
failIfNotData(state, i)
val ctx =
try parseNum(i, stackHead.narrow, stackHead.subVisitor.asInstanceOf[Visitor[_, J]])
catch reject(i)
parseNested(collectionEndFor(stackHead), ctx, stackHead, stackTail)
case 't' =>
failIfNotData(state, i)
try stackHead.narrow.visitValue(
parseTrue(i, stackHead.subVisitor.asInstanceOf[Visitor[_, J]]),
i
)
catch reject(i)
parseNested(collectionEndFor(stackHead), i + 4, stackHead, stackTail)
case 'f' =>
failIfNotData(state, i)
try stackHead.narrow.visitValue(
parseFalse(i, stackHead.subVisitor.asInstanceOf[Visitor[_, J]]),
i
)
catch reject(i)
parseNested(collectionEndFor(stackHead), i + 5, stackHead, stackTail)
case 'n' =>
failIfNotData(state, i)
try stackHead.narrow.visitValue(
parseNull(i, stackHead.subVisitor.asInstanceOf[Visitor[_, J]]),
i
)
catch reject(i)
parseNested(collectionEndFor(stackHead), i + 4, stackHead, stackTail)
case ',' =>
dropBufferUntil(i)
(state: @switch) match{
case ARREND => parseNested(DATA, i + 1, stackHead, stackTail)
case OBJEND => parseNested(KEY, i + 1, stackHead, stackTail)
case _ => dieWithFailureMessage(i, state)
}
case ']' =>
(state: @switch) match{
case ARREND | ARRBEG =>
tryCloseCollection(stackHead, stackTail, i) match{
case Some(t) => t
case None =>
val stackTailHead = stackTail.head
parseNested(collectionEndFor(stackTailHead), i + 1, stackTailHead, stackTail.tail)
}
case _ => dieWithFailureMessage(i, state)
}
case '}' =>
(state: @switch) match{
case OBJEND | OBJBEG =>
tryCloseCollection(stackHead, stackTail, i) match{
case Some(t) => t
case None =>
val stackTailHead = stackTail.head
parseNested(collectionEndFor(stackTailHead), i + 1, stackTailHead, stackTail.tail)
}
case _ => dieWithFailureMessage(i, state)
}
case _ => dieWithFailureMessage(i, state)
}
}
def dieWithFailureMessage(i: Int, state: Int) = {
val expected = state match{
case ARRBEG => "json value or ]"
case OBJBEG => "json value or }"
case DATA => "json value"
case KEY => "json string key"
case COLON => ":"
case ARREND => ", or ]"
case OBJEND => ", or }"
}
die(i, s"expected $expected")
}
def failIfNotData(state: Int, i: Int) = (state: @switch) match{
case DATA | ARRBEG => // do nothing
case _ => dieWithFailureMessage(i, state)
}
def tryCloseCollection(stackHead: ObjArrVisitor[_, J], stackTail: List[ObjArrVisitor[_, J]], i: Int) = {
if (stackTail.isEmpty) {
Some(try stackHead.visitEnd(i) catch reject(i), i + 1)
} else {
val ctxt2 = stackTail.head.narrow
try ctxt2.visitValue(stackHead.visitEnd(i), i) catch reject(i)
None
}
}
def collectionEndFor(stackHead: ObjArrVisitor[_, _]) = {
if (stackHead.isObj) OBJEND
else ARREND
}
/**
* See if the string has any escape sequences. If not, return the
* end of the string. If so, bail out and return -1.
*
* This method expects the data to be in UTF-16 and accesses it as
* chars.
*/
protected[this] final def parseStringSimple(i: Int): Int = {
var j = i
var c = elemOps.toUnsignedInt(getByteSafe(j))
while (c != '"') {
if (c < ' ') die(j, s"control char (${c}) in string")
if (c == '\\' || c > 127) return -1 - j
j += 1
c = elemOps.toUnsignedInt(getByteSafe(j))
}
j + 1
}
/**
* Parse a string that is known to have escape sequences.
*/
protected[this] final def parseStringComplex(i0: Int): Int = {
var i = i0
var c = elemOps.toUnsignedInt(getByteSafe(i))
while (c != '"') {
if (c < ' ') die(i, s"control char (${c}) in string")
else if (c == '\\') {
(getByteSafe(i + 1): @switch) match {
case 'b' => { outputBuilder.append('\b'); i += 2 }
case 'f' => { outputBuilder.append('\f'); i += 2 }
case 'n' => { outputBuilder.append('\n'); i += 2 }
case 'r' => { outputBuilder.append('\r'); i += 2 }
case 't' => { outputBuilder.append('\t'); i += 2 }
case '"' => { outputBuilder.append('"'); i += 2 }
case '/' => { outputBuilder.append('/'); i += 2 }
case '\\' => { outputBuilder.append('\\'); i += 2 }
// if there's a problem then descape will explode
case 'u' =>
val d = descape(i)
outputBuilder.appendC(d)
i += 6
case c => die(i + 1, s"illegal escape sequence after \\")
}
} else {
// this case is for "normal" code points that are just one Char.
//
// we don't have to worry about surrogate pairs, since those
// will all be in the ranges D800–DBFF (high surrogates) or
// DC00–DFFF (low surrogates).
outputBuilder.append(c)
i += 1
}
c = elemOps.toUnsignedInt(getByteSafe(i))
}
i + 1
}
/**
* Parse the string according to JSON rules, and add to the given
* context.
*
* This method expects the data to be in UTF-16, and access it as
* Char. It performs the correct checks to make sure that we don't
* interpret a multi-char code point incorrectly.
*/
protected[this] final def parseStringValue(i: Int, stackHead: ObjArrVisitor[_, J]): Int = {
val k = parseStringSimple(i + 1)
if (k >= 0) {
visitString(i, unsafeCharSeqForRange(i + 1, k - i - 2), stackHead)
k
} else {
val k2 = parseStringToOutputBuilder(i, k)
visitString(i, outputBuilder.makeString(), stackHead)
k2
}
}
protected[this] final def parseStringKey(i: Int, stackHead: ObjArrVisitor[_, J]): Int = {
val k = parseStringSimple(i + 1)
if (k >= 0) {
visitStringKey(i, unsafeCharSeqForRange(i + 1, k - i - 2), stackHead)
k
} else {
val k2 = parseStringToOutputBuilder(i, k)
visitStringKey(i, outputBuilder.makeString(), stackHead)
k2
}
}
def parseStringToOutputBuilder(i: Int, k: Int) = {
outputBuilder.reset()
appendBytesToBuilder(outputBuilder, i + 1, -k - 2 - i)
val k2 = parseStringComplex(-k - 1)
k2
}
def visitString(i: Int, s: CharSequence, stackHead: ObjArrVisitor[_, J]) = {
val v = stackHead.subVisitor.visitString(s, i)
stackHead.narrow.visitValue(v, i)
}
def visitStringKey(i: Int, s: CharSequence, stackHead: ObjArrVisitor[_, J]) = {
val obj = stackHead.asInstanceOf[ObjVisitor[Any, _]]
val keyVisitor = obj.visitKey(i)
obj.visitKeyValue(keyVisitor.visitString(s, i))
}
protected[this] final def parseStringTopLevel(i: Int, facade: Visitor[_, J]): (J, Int) = {
val k = parseStringSimple(i + 1)
if (k >= 0) {
val res = facade.visitString(unsafeCharSeqForRange(i + 1, k - i - 2), i)
(res, k)
} else {
val k2 = parseStringToOutputBuilder(i, k)
val res = facade.visitString(outputBuilder.makeString(), i)
(res, k2)
}
}
}
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