json

package json

This package provides extensions to the core "spac" library which allow for the handling of JSON data.

Rather than creating explicit classes that extend Parser, Transformer, and Splitter, this package provides type aliases and implicit extensions. For example, JsonParser[A] is just a type alias for Parser[JsonEvent, A], and JsonParser is just a call to Parser[JsonEvent].

Implicit JsonParsers are available for each of the JSON primitive types:

string
number (expressed as Int, Long, Float, or Double)
boolean
null (expressed as None.type)

Helpers are available for parsing JSON arrays and objects:

JsonParser.listOf[A] to parse an array where each value is an A
JsonParser.objectOf[A] to parse an object where the value for each field an A
JsonParser.objectOfNullable[A] to parse an object where the value for each field is either null or an A, filtering out the nulls
JsonParser.fieldOf[A](fieldName) to parse a specific field from an object

A DSL for creating json-specific ContextMatchers is provided to make it more convenient to call Splitter.json. For example:

Splitter.json("foo" \ "bar").as[String].parseFirst

Can be used to capture rootJson.foo.bar as a String in

{
  "foo": {
    "bar": "hello"
  }
}

To "split" values inside arrays, index-related context matchers are available, e.g.

Splitter.json("foo" \ anyIndex).as[Int].parseToList

Can be used to capture each of the numbers in the "foo" array in

{
  "foo": [1, 2, 3]
}

A note about JsonEvents in spac: JSON doesn't have any explicit markers for when a field ends, or when an array index starts or ends; those context changes are essentially inferred by the presence of some other event. For example, instead of a "field end" event, typically there will be either a new "field start" or a token representing the end of the current object. With spac, splitters and context matchers generally operate under the assumption that a "stack push" event (like a field start) will eventually be followed by a corresponding "stack pop" event (i.e. field end).

To allow for this, these "inferred" events (FieldEnd, IndexStart, IndexEnd) are explicitly represented as JsonEvents in the stream being parsed. Keep this in mind when creating JSON ContextMatchers:

field-related matchers will match a stack like case ObjectStart :: FieldStart(_) :: _
index-related matchers will match a stack like case ArrayStart :: IndexStart(_) :: _

Source: package.scala

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type JsonContextMatcher[+C] = ContextMatcher[JsonStackElem, C]
sealed trait JsonEvent extends HasLocation
ADT for tokens in a JSON stream.
type JsonParser[+Out] = Parser[JsonEvent, Out]
Type alias for a Parser whose input type is JsonEvent
implicit final class JsonParserApplyOps extends AnyVal
Provides JSON-specific Parser constructor methods to the JsonParser object, for example JsonParser.fieldOf.
Provides JSON-specific Parser constructor methods to the JsonParser object, for example JsonParser.fieldOf.
Technically JsonParser is not a companion object, it is a partially-applied version of the Parser companion object which binds the input type to JsonEvent, so "companion methods" must instead be added as extension methods.
type JsonSplitter[+C] = Splitter[JsonEvent, C]
Type alias for a Splitter whose input type is JsonEvent
implicit final class JsonSplitterApplyOps extends AnyVal
Adds Splitter.json, for constructing json context matcher-based JsonSplitters
implicit final class JsonSplitterOps[C] extends AnyVal
Adds splitter.asNullable[A], for handling possibly-null values in a JSON substream
sealed trait JsonStackElem extends JsonEvent
Subset of JsonEvents that constitute a "context stack push".
sealed trait JsonStackPop extends JsonEvent
Subset of JsonEvents that constitute a "context stack pop".
type JsonTransformer[+Out] = Transformer[JsonEvent, Out]
Type alias for a Transformer whose input type is JsonEvent.
sealed trait JsonValueEvent extends JsonEvent
Subset of JsonEvents that represent a primitive values

Value Members

val JsonParser: ParserApplyWithBoundInput[JsonEvent]
Like the Parser companion object, but only for creating Parsers whose input type is JsonEvent.
Like the Parser companion object, but only for creating Parsers whose input type is JsonEvent.
See also
JsonParserApplyOps
val JsonSplitter: SplitterApplyWithBoundInput[JsonEvent]
Like the Splitter companion object, but only for creating Splitters whose input type is JsonEvent.
val JsonTransformer: TransformerApplyWithBoundInput[JsonEvent]
Like the Transformer companion object, but only for creating Transformers whose input type is JsonEvent.
def anyField: JsonContextMatcher[String]
Context matcher that matches events with any JSON object field, capturing the name of the field as context.
Context matcher that matches events with any JSON object field, capturing the name of the field as context. Specifically this matcher looks for an ObjectStart followed by a FieldStart(name), for any name.
def anyIndex: JsonContextMatcher[Int]
Context matcher that matches events within a JSON array, at any index.
Context matcher that matches events within a JSON array, at any index. Specifically this matcher looks for an ArrayStart followed by an IndexStart(_) in the JSON context stack. If the match succeeds, the i index will be captured as a context value.
def field[A](contextFromName: (String) => Option[A]): JsonContextMatcher[A]
Context matcher that matches events within certain JSON object fields, extracting some context value based on the name of the matched field.
Context matcher that matches events within certain JSON object fields, extracting some context value based on the name of the matched field. Specifically this matcher looks for an ObjectStart followed by a FieldStart(name), then plugs the name into contextFromName. If contextFromName returns a Some, the match succeeds and the value inside the Some is returned.
contextFromName
a function that extracts a context value based on the name of the JSON object field
implicit def field(name: String): JsonContextMatcher[Unit]
Context matcher that matches events within a given JSON object field.
Context matcher that matches events within a given JSON object field. Specifically this matcher looks for an ObjectStart followed by a FieldStart(name) in the JSON context stack.
When calling Splitter.json, the fact that this method is implicit allows you to use the underlying field name directly instead of directly calling this method, e.g. Splitter.json("address" \ "street")
name
the name of the field
def fieldWhere(f: (String) => Boolean): JsonContextMatcher[String]
Context matcher that matches events within JSON object fields whose names case the given f predicate to return true.
Context matcher that matches events within JSON object fields whose names case the given f predicate to return true. Specifically this matcher looks for an ObjectStart followed by a FieldStart(name) where f(name) is true. If the match succeeds, the name of the field is also extracted as a context value.
f
A predicate applied to field names to determine whether the current JSON context stack matches
def index[A](contextFromIndex: (Int) => Option[A]): JsonContextMatcher[A]
Context matcher that matches events within a JSON array, at certain indexes.
Context matcher that matches events within a JSON array, at certain indexes. Specifically this matcher looks for an ArrayStart followed by an IndexStart(i) in the JSON context stack, where the i from the IndexStart is passed to contextFromIndex. If contextFromIndex(i) returns a Some, the match succeeds and the value inside the Some is returned as a context value.
def index(i: Int): JsonContextMatcher[Unit]
Context matcher that matches events within a JSON array at a specific index.
Context matcher that matches events within a JSON array at a specific index. Specifically this matcher looks for an ArrayStart followed by an IndexStart(i) in the JSON context stack.
def indexWhere(f: (Int) => Boolean): JsonContextMatcher[Int]
Context matcher that matches events within a JSON array, at certain indexes.
Context matcher that matches events within a JSON array, at certain indexes. Specifically this matcher looks for an ArrayStart followed by an IndexStart(i) in the JSON context stack, where f(i) is true. If the match succeeds, the i index will be captured as a context value.
implicit val jsonParserForPrimitiveBoolean: JsonParser[Boolean]
Implicit version of JsonParser.forBoolean
implicit val jsonParserForPrimitiveDouble: JsonParser[Double]
Implicit version of JsonParser.forDouble
implicit val jsonParserForPrimitiveFloat: JsonParser[Float]
Implicit version of JsonParser.forFloat
implicit val jsonParserForPrimitiveInt: JsonParser[Int]
Implicit version of JsonParser.forInt
implicit val jsonParserForPrimitiveLong: JsonParser[Long]
Implicit version of JsonParser.forLong
implicit val jsonParserForPrimitiveNull: JsonParser[None.type]
Implicit version of JsonParser.forNull
implicit val jsonParserForPrimitiveString: JsonParser[String]
Implicit version of JsonParser.forString
object Fs2DataSource
Provides helpers for creating FS2 streams of io.dylemma.spac.json.JsonEvent, using fs2-data-json as the underlying event provider.
Provides helpers for creating FS2 streams of io.dylemma.spac.json.JsonEvent, using fs2-data-json as the underlying event provider.
This helper is set up to mirror the layout of the corresponding Fs2DataSource helper in the fs2-data-xml support module, but since there's less customization involved in setting up a stream of fs2-data-json Token objects, there's a lot less going on in this object. The main functionality provided here is the convert pipe, and some small helpers to automatically call it.
For example:
```
val charStream: Stream[IO, Char] = ???

// this...
val jsonStream1: Stream[IO, JsonEvent] = {
  import fs2.data.json._
  charStream
    .through(tokens)
    .through(Fs2DataSource.convertEvents)
}

// could be replaced with
val jsonStream2: Stream[IO, JsonEvent] = {
  Fs2DataSource[IO](charStream)
}
```
Essentially this helper just provides a convenient apply method that accepts String, Stream[F, Char], Stream[F, String], or Stream[F, fs2.data.json.Token] to return a Stream[F, JsonEvent] which a JsonParser could then interact with.
object JacksonSource
Provides helpers for creating fs2.Stream and Iterator instances of JsonEvent from various underlying event sources, using the Jackson library as the underlying event parser.
Provides helpers for creating fs2.Stream and Iterator instances of JsonEvent from various underlying event sources, using the Jackson library as the underlying event parser.
The helpers in this object operate in terms of the IntoJacksonJsonParser typeclass, which defines logic for using a source value to construct a Jackson JsonParser in a Resource. From there, the helpers take care of converting the jackson parser/event model to the spac JsonEvent model.
For example:
```
val file = new File("./stuff.json")
val jsonStream: Stream[IO, JsonEvent] = JacksonSource[IO](file)
```
object JsonEvent

Packages

json

package json

Type Members

Value Members

Inherited from AnyRef

Inherited from Any

JSON-specific extensions for Parser and Splitter

JSON-specific Type and Value aliases

JSON Context Matcher Construction

JSON Event Representation

Backend Parser Support

Packages

json

package json

Type Members

Value Members

Inherited from AnyRef

Inherited from Any

JSON-specific extensions for Parser and Splitter

JSON-specific Type and Value aliases

JSON Context Matcher Construction

JSON Event Representation

Backend Parser Support

json