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fixed seq parsing
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Greg Zoller committed Oct 24, 2023
1 parent 766f55a commit b6bd07e
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Showing 3 changed files with 301 additions and 241 deletions.
357 changes: 212 additions & 145 deletions src/main/scala/co.blocke.scalajack/json/JsonParser.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -5,153 +5,220 @@ import scala.util.*

case class ParseError(msg: String) extends Throwable

case class JsonParser( js: String ):

private val jsChars: Array[Char] = js.toCharArray
private var i = 0
private val max: Int = jsChars.length

// Housekeeping
//------------------------------
@inline def nullCheck: Boolean =
val res = i+3<max && jsChars(i)=='n' && jsChars(i+1)=='u' && jsChars(i+2)=='l' && jsChars(i+3)=='l'
if res then i += 4
res
@inline def eatWhitespace: Either[ParseError,Unit] =
while (i < max && jsChars(i).isWhitespace) i += 1
Right(())
@inline def expectComma: Either[ParseError,Unit] = // Note: this consumes whitespace before/after the ','
for {
_ <- eatWhitespace
r <- if jsChars(i) == ',' then
i += 1
eatWhitespace
Right(())
else
Left(ParseError(s"Expected comma at position [$i]"))
} yield r
@inline def expectColon: Either[ParseError,Unit] = // Note: this consumes whitespace before/after the ':'
for {
_ <- eatWhitespace
r <- if jsChars(i) == ':' then
i += 1
eatWhitespace
Right(())
else
Left(ParseError(s"Expected colon at position [$i]"))
} yield r

// JSON label (i.e. object key, which is always a simple string)
def expectLabel: Either[ParseError,String] =
jsChars(i) match
case '"' =>
i += 1
val mark = i
while (i < max && jsChars(i) != '"') i += 1
i += 1
Right(js.substring(mark, i-1))
case x => Left(ParseError(s"Unexpected character '$x' where beginning of label expected at position [$i]"))


// Data Types
//------------------------------
def expectBoolean(cfg: JsonConfig): Either[ParseError,Boolean] =
jsChars(i) match
case 't' if i+3<max && jsChars(i+1)=='r' && jsChars(i+2)=='u' && jsChars(i+3)=='e' =>
i += 4
Right(true)
case 'f' if i+4<max && jsChars(i+1)=='a' && jsChars(i+2)=='l' && jsChars(i+3)=='s' && jsChars(i+3)=='e' =>
i += 5
Right(false)
case x => Left(ParseError(s"Unexpected character '$x' where beginning of boolean value expected at position [$i]"))

def expectLong(cfg: JsonConfig): Either[ParseError,Long] =
val mark = i
var done = false
while !done do
jsChars(i) match
case c if (c >= '0' && c <= '9') || c == '-' => i += 1
case _ => done = true
Try( js.substring(mark,i).toLong ) match
case Success(g) => Right(g)
case Failure(f) =>
val msg = if mark == i then
s"""Int/Long expected but couldn't parse from "${jsChars(i)}" at position [$i]"""
else
s"""Int/Long expected but couldn't parse from "${js.substring(mark,i)}" at position [$i]"""
i = mark
Left(ParseError(msg))

def expectDouble(cfg: JsonConfig): Either[ParseError,Double] =
case class JsonParser(js: String):

private val jsChars: Array[Char] = js.toCharArray
private var i = 0
private val max: Int = jsChars.length

// Housekeeping
// ------------------------------
@inline def nullCheck: Boolean =
val res = i + 3 < max && jsChars(i) == 'n' && jsChars(i + 1) == 'u' && jsChars(i + 2) == 'l' && jsChars(i + 3) == 'l'
if res then i += 4
res
@inline def eatWhitespace: Either[ParseError, Unit] =
while i < max && jsChars(i).isWhitespace do i += 1
Right(())
@inline def expectComma: Either[ParseError, Unit] = // Note: this consumes whitespace before/after the ','
for {
_ <- eatWhitespace
r <-
if jsChars(i) == ',' then
i += 1
eatWhitespace
Right(())
else Left(ParseError(s"Expected comma at position [$i]"))
} yield r
@inline def expectColon: Either[ParseError, Unit] = // Note: this consumes whitespace before/after the ':'
for {
_ <- eatWhitespace
r <-
if jsChars(i) == ':' then
i += 1
eatWhitespace
Right(())
else Left(ParseError(s"Expected colon at position [$i]"))
} yield r

// JSON label (i.e. object key, which is always a simple string, ie no escaped/special chars)
def expectLabel: Either[ParseError, String] =
jsChars(i) match
case '"' =>
i += 1
val mark = i
var done = false
while !done do
jsChars(i) match
case c if (c >= '0' && c <= '9') || c == '-' || c == '.' || c == 'e' || c == 'E' || c == '+' => i += 1
case _ => done = true
Try( js.substring(mark,i-1).toDouble ) match
case Success(g) => Right(g)
case Failure(_) =>
val msg = if mark == i then
s"Float/Double expected but couldn't parse from \"${jsChars(i)}\" at position [$i]"
else
s"Float/Double expected but couldn't parse from \"${js.substring(mark,i-1)}\" at position [$i]"
i = mark
Left(ParseError(msg))

def expectOption[T](cfg: JsonConfig, expectElement: JsonConfig=>Either[ParseError,T]): Either[ParseError, Option[T]] =
nullCheck match
case false => expectElement(cfg).map(t => Some(t))
case true if cfg.noneAsNull => Right(None)
case true if cfg.forbidNullsInInput => Left(ParseError(s"Forbidden 'null' value received at position [$i]"))
case true => Right(Some(null.asInstanceOf[T]))

def expectList[T]( cfg: JsonConfig, expectElement: JsonConfig=>Either[ParseError,T]): Either[ParseError,List[T]] =
if jsChars(i) != '[' then Left(ParseError(s"Beginning of list expected at position [$i]"))
else
while i < max && jsChars(i) != '"' do i += 1
i += 1
Right(js.substring(mark, i - 1))
case x => Left(ParseError(s"Unexpected character '$x' where beginning of label expected at position [$i]"))

// Data Types
// ------------------------------
def expectBoolean(cfg: JsonConfig, p: JsonParser): Either[ParseError, Boolean] =
jsChars(i) match
case 't' if i + 3 < max && jsChars(i + 1) == 'r' && jsChars(i + 2) == 'u' && jsChars(i + 3) == 'e' =>
i += 4
Right(true)
case 'f' if i + 4 < max && jsChars(i + 1) == 'a' && jsChars(i + 2) == 'l' && jsChars(i + 3) == 's' && jsChars(i + 3) == 'e' =>
i += 5
Right(false)
case x => Left(ParseError(s"Unexpected character '$x' where beginning of boolean value expected at position [$i]"))

def expectLong(cfg: JsonConfig, p: JsonParser): Either[ParseError, Long] =
val mark = i
var done = false
while !done do
jsChars(i) match
case c if (c >= '0' && c <= '9') || c == '-' => i += 1
case _ => done = true
Try(js.substring(mark, i).toLong) match
case Success(g) => Right(g)
case Failure(f) =>
val msg =
if mark == i then s"""Int/Long expected but couldn't parse from "${jsChars(i)}" at position [$i]"""
else s"""Int/Long expected but couldn't parse from "${js.substring(mark, i)}" at position [$i]"""
i = mark
Left(ParseError(msg))

def expectDouble(cfg: JsonConfig, p: JsonParser): Either[ParseError, Double] =
val mark = i
var done = false
while !done do
jsChars(i) match
case c if (c >= '0' && c <= '9') || c == '-' || c == '.' || c == 'e' || c == 'E' || c == '+' => i += 1
case _ => done = true
Try(js.substring(mark, i - 1).toDouble) match
case Success(g) => Right(g)
case Failure(_) =>
val msg =
if mark == i then s"Float/Double expected but couldn't parse from \"${jsChars(i)}\" at position [$i]"
else s"Float/Double expected but couldn't parse from \"${js.substring(mark, i - 1)}\" at position [$i]"
i = mark
Left(ParseError(msg))

def expectString(cfg: JsonConfig, p: JsonParser): Either[ParseError, String] =
nullCheck match
case true if cfg.forbidNullsInInput => Left(ParseError(s"Forbidden 'null' value received at position [$i]"))
case true => Right(null.asInstanceOf[String])
case false =>
jsChars(i) match
case '"' =>
i += 1
val mark = i // save position in case we need complex string parse
var captured: Option[String] = None
while i < max && jsChars(i) != '"' do
jsChars(i) match
case '\\' => // oops! special char found--do slow string parse
i = mark
captured = Some(_expectString)
case _ => i += 1
i += 1
Right(captured.getOrElse(js.substring(mark, i - 1)))
case x => Left(ParseError(s"Unexpected character '$x' where beginning of label expected at position [$i]"))

def expectOption[T](cfg: JsonConfig, expectElement: (JsonConfig, JsonParser) => Either[ParseError, T]): Either[ParseError, Option[T]] =
nullCheck match
case false => expectElement(cfg, this).map(t => Some(t))
case true if cfg.noneAsNull => Right(None)
case true if cfg.forbidNullsInInput => Left(ParseError(s"Forbidden 'null' value received at position [$i]"))
case true => Right(Some(null.asInstanceOf[T]))

def expectList[T](cfg: JsonConfig, expectElement: (JsonConfig, JsonParser) => Either[ParseError, T]): Either[ParseError, List[T]] =
if jsChars(i) != '[' then Left(ParseError(s"Beginning of list expected at position [$i]"))
else
i += 1
eatWhitespace
val acc = scala.collection.mutable.ListBuffer.empty[T]
var done: Option[Either[ParseError, List[T]]] = None
while done.isEmpty do
(for {
el <- expectElement(cfg, this)
_ = acc.addOne(el)
_ <- expectComma
} yield el) match
case Left(_) if jsChars(i) == ']' =>
i += 1
eatWhitespace
val acc = scala.collection.mutable.ListBuffer.empty[T]
var done: Option[Either[ParseError,List[T]]] = None
while done.isEmpty do
(for {
el <- expectElement(cfg)
_ = acc.addOne(el)
_ <- expectComma
} yield el) match
case Left(_) if jsChars(i) == ']' =>
i += 1
eatWhitespace
done = Some(Right(acc.toList))
case Left(e) =>
done = Some(Left(e))
case Right(_) =>
done.get

def expectClass[T](
cfg: JsonConfig,
fieldMap: Map[String, (JsonConfig) => Either[ParseError, ?]],
instantiator: Map[String, ?] => T
): Either[ParseError,T] =
if jsChars(i) != '{' then Left(ParseError(s"Beginning of object expected at position [$i]"))
else
done = Some(Right(acc.toList))
case Left(e) =>
done = Some(Left(e))
case Right(_) =>
done.get

def expectClass[T](
cfg: JsonConfig,
fieldMap: Map[String, (JsonConfig, JsonParser) => Either[ParseError, ?]],
instantiator: Map[String, ?] => T
): Either[ParseError, T] =
if jsChars(i) != '{' then Left(ParseError(s"Beginning of object expected at position [$i]"))
else
i += 1
eatWhitespace
var done: Option[Either[ParseError, T]] = None
val fields = scala.collection.mutable.HashMap.empty[String, Any]
while done.isEmpty do
(for {
fieldLabel <- expectLabel
_ <- expectColon
fieldValue <- fieldMap(fieldLabel)(cfg, this)
_ = fields.put(fieldLabel, fieldValue)
_ <- expectComma
} yield fieldValue) match
case Left(_) if jsChars(i) == '}' =>
i += 1
eatWhitespace
var done: Option[Either[ParseError,T]] = None
val fields = scala.collection.mutable.HashMap.empty[String,Any]
while done.isEmpty do
(for {
fieldLabel <- expectLabel
_ <- expectColon
fieldValue <- fieldMap(fieldLabel)(cfg)
_ = fields.put(fieldLabel, fieldValue)
_ <- expectComma
} yield fieldValue) match
case Left(_) if jsChars(i) == '}' =>
i += 1
eatWhitespace
done = Some(Right( instantiator(fields.toMap) )) // instantiate the class here!!!
case Left(e) =>
done = Some(Left(e))
case Right(_) =>
done.get
done = Some(Right(instantiator(fields.toMap))) // instantiate the class here!!!
case Left(e) =>
done = Some(Left(e))
case Right(_) =>
done.get

// Slower String parsing that handles special escaped chars
def _expectString =
val builder = new java.lang.StringBuilder()
while i < max && jsChars(i) != '"' do
if jsChars(i) == '\\' then {
jsChars(i + 1) match {
case '"' =>
builder.append('\"')
i += 2

case '\\' =>
builder.append('\\')
i += 2

case 'b' =>
builder.append('\b')
i += 2

case 'f' =>
builder.append('\f')
i += 2

case 'n' =>
builder.append('\n')
i += 2

case 'r' =>
builder.append('\r')
i += 2

case 't' =>
builder.append('\t')
i += 2

case 'u' =>
val hexEncoded = js.substring(i + 2, i + 6)
val unicodeChar = Integer.parseInt(hexEncoded, 16).toChar
builder.append(unicodeChar.toString)
i += 6

case c =>
builder.append(c)
i += 2
}
} else {
builder.append(jsChars(i))
i += 1
}
builder.toString
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