Packages

  • package root
    Definition Classes
    root
  • package io
    Definition Classes
    root
  • package dylemma
    Definition Classes
    io
  • package spac

    SPaC (short for "Streaming Parser Combinators") is a library for building stream consumers in a declarative style, specialized for tree-like data types like XML and JSON.

    SPaC (short for "Streaming Parser Combinators") is a library for building stream consumers in a declarative style, specialized for tree-like data types like XML and JSON.

    Many utilities for handling XML and JSON data involve parsing the entire "document" to some DOM model, then inspecting and transforming that model to extract information. The downside to these utilities is that when the document is very large, the DOM may not fit in memory. The workaround for this type of problem is to treat the document as a stream of "events", e.g. "StartElement" and "EndElement" for XML, or "StartObject" and "EndObject" for JSON. The downside to this workaround is that writing code to handle these streams can be complicated and error-prone, especially when the DOM is complicated.

    SPaC's goal is to drastically simplify the process of creating code to handle these streams.

    This package contains the "core" SPaC traits; Parser, Transformer, Splitter, and ContextMatcher.

    See the xml and json subpackages (provided by the xml-spac and json-spac libraries respectively) for specific utilities related to handling XML and JSON event streams.

    Definition Classes
    dylemma
  • package interop
    Definition Classes
    spac
  • package json

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

    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(_) :: _
    Definition Classes
    spac
  • package xml

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

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

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

    Three main Parser methods are added to Parser[XmlEvent] via the XmlParserApplyOps implicit class:

    • XmlParser.forText - for capturing raw text
    • XmlParser.attr - for capturing mandatory attributes from elements
    • XmlParser.attrOpt - for capturing optional attributes from elements

    One main Splitter constructor method is added to Splitter via the XmlSplitterApplyOps implicit class:

    • Splitter.xml - for creating splitters based on an inspection of an "element stack"

    Three main Splitter member methods are added to Splitter[XmlEvent, C] via the XmlSplitterOps implicit class:

    • .attr - alias for .joinBy(XmlParser.attr(...))
    • .attrOpt - alias for .joinBy(XmlParser.attrOpt(...))
    • .text - alias for .joinBy(XmlParser.forText)

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

    Splitter.xml("things" \ "thing").attr("foo").parseToList

    Can be used to capture a list of the "foo" attributes in the <thing> elements in

    <things>
       <thing foo="hello" />
       <thing foo="Goodbye">
          <extra>junk</extra>
       </thing>
    </thing>
    Definition Classes
    spac
  • CallerPos
  • ContextChange
  • ContextLocation
  • ContextMatcher
  • ContextPop
  • ContextPush
  • ContextTrace
  • HasLocation
  • LowPriorityTypeReduceImplicits
  • Parser
  • ParserApplyWithBoundInput
  • Signal
  • SingleItemContextMatcher
  • Source
  • SpacException
  • SpacTraceElement
  • Splitter
  • SplitterApplyWithBoundInput
  • StackInterpretation
  • StackLike
  • Transformer
  • TransformerApplyWithBoundInput
  • TypeReduce
  • Unconsable

trait ContextMatcher[Elem, +A] extends AnyRef

An object responsible for inspecting a stack of StartElement events and determining if they correspond to some "context" value of type A.

ContextMatchers play a primary role in splitting an XML event stream into "substreams", i.e. each substream is defined as the series of consecutive events during which the XML tag stack matches a context.

ContextMatchers are intended to be transformed and combined with each other in order to build up more complex matching functionality. See also: SingleElementContextMatcher, which contains additional combination methods and some specialized transformation methods.

A

The type of the matched context.

Source
ContextMatcher.scala
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Inherited
  1. ContextMatcher
  2. AnyRef
  3. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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Visibility
  1. Public
  2. Protected

Abstract Value Members

  1. abstract def applyChained[B](stack: IndexedSeq[Elem], offset: Int, avail: Int, next: ContextMatcher[Elem, B]): Option[(A, B)]

    The underlying context match method.

    The underlying context match method.

    Inspects the elements in the XML "tag stack", which is essentially a List[StartElement], but for performance reasons is represented as an array with an "offset" index and a number of available elements from that offset. If the elements correspond to a context value of A, the implementation must then pass the remaining elements of the stack to the next matcher, i.e. by calling next(stack, offset + numConsumed, avail - numConsumed).

    The next matcher is necessary in order to support non-greedy matchers, e.g. ContextMatcher.variableLength, a.k.a. **. Without a reference to the next matcher in the chain, matcher implementations would be forced to pick a fixed number of elements for matching, never knowing that the overall match could have succeeded if they had consumed some additional elements.

    B

    The next matcher's context type

    stack

    A reference to the complete XML "tag stack". Note that the responsibility of this method is limited to a *slice* of this value, as defined by offset and avail.

    offset

    The index of the first element to be considered by the matching logic. From this method's point of view, the "first" element in the stack is actually at stack(offset)

    avail

    The number of elements available in the stack starting from the offset.

    next

    The next matcher in the chain.

    returns

    If the match succeeded, and the next match succeded, an Option containing a tuple of both match results. If the match failed, or if the next match failed, None.

Concrete Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##: Int
    Definition Classes
    AnyRef → Any
  3. def +(other: String): String
    Implicit
    This member is added by an implicit conversion from ContextMatcher[Elem, A] toany2stringadd[ContextMatcher[Elem, A]] performed by method any2stringadd in scala.Predef.
    Definition Classes
    any2stringadd
  4. def ->[B](y: B): (ContextMatcher[Elem, A], B)
    Implicit
    This member is added by an implicit conversion from ContextMatcher[Elem, A] toArrowAssoc[ContextMatcher[Elem, A]] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()
  5. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  6. def \[A1 >: A, B, R](next: ContextMatcher[Elem, B])(implicit reduce: Aux[A1, B, R]): ContextMatcher[Elem, R]

    Create a new matcher by forming a chain with this matcher at the front, and the next matcher at the back.

    Create a new matcher by forming a chain with this matcher at the front, and the next matcher at the back. In other words, a matcher for a context within another context.

    A1

    To satisfy covariance on A

    B

    The next matcher's context type

    R

    The "reduced" content type, derived from the tuple type (A, B) based on the reduce rule.

    next

    A matcher which will be used to match the "inner" context

    reduce

    The TypeReduce rule to help omit Unit from the resulting context type

    returns

    A matcher which delegates to this matcher first, then the next matcher for the remaining stack.

  7. def apply(stack: IndexedSeq[Elem], offset: Int, avail: Int): Option[A]

    The main context match method.

    The main context match method.

    Inspects the elements in the XML "tag stack", which is essentially a List[StartElement], but for performance reasons is represented as an array with an "offset" index and a number of available elements from that offset. If the elements correspond to a context value of A, the implementation must then pass the remaining elements of the stack to the next matcher, i.e. by calling next(stack, offset + numConsumed, avail - numConsumed).

    The difference between this method and applyChained is the lack of the next parameter; in this method, the current matcher is assumed to be the end of the chain.

    stack

    A reference to the complete XML "tag stack". Note that the responsibility of this method is limited to a *slice* of this value, as defined by offset and avail.

    offset

    The index of the first element to be considered by the matching logic. From this method's point of view, the "first" element in the stack is actually at stack(offset)

    avail

    The number of elements available in the stack starting from the offset.

    returns

    An option containing the successfully-matched context, or None.

  8. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  9. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.CloneNotSupportedException]) @native()
  10. def ensuring(cond: (ContextMatcher[Elem, A]) => Boolean, msg: => Any): ContextMatcher[Elem, A]
    Implicit
    This member is added by an implicit conversion from ContextMatcher[Elem, A] toEnsuring[ContextMatcher[Elem, A]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  11. def ensuring(cond: (ContextMatcher[Elem, A]) => Boolean): ContextMatcher[Elem, A]
    Implicit
    This member is added by an implicit conversion from ContextMatcher[Elem, A] toEnsuring[ContextMatcher[Elem, A]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  12. def ensuring(cond: Boolean, msg: => Any): ContextMatcher[Elem, A]
    Implicit
    This member is added by an implicit conversion from ContextMatcher[Elem, A] toEnsuring[ContextMatcher[Elem, A]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  13. def ensuring(cond: Boolean): ContextMatcher[Elem, A]
    Implicit
    This member is added by an implicit conversion from ContextMatcher[Elem, A] toEnsuring[ContextMatcher[Elem, A]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  14. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  15. def equals(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef → Any
  16. def filter(p: (A) => Boolean): ContextMatcher[Elem, A]

    Create a new ContextMatcher which takes the match result of this matcher and passes it through the validation function f.

    Create a new ContextMatcher which takes the match result of this matcher and passes it through the validation function f. If f returns false, the match is unsuccessful.

    p

    The filter predicate, i.e. the validation function

    returns

    A new matcher with validated results

  17. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.Throwable])
  18. def flatMap[B](f: (A) => Option[B]): ContextMatcher[Elem, B]

    Create a new ContextMatcher which takes the match result of this matcher and passes it through the combined transformation/validation function f.

    Create a new ContextMatcher which takes the match result of this matcher and passes it through the combined transformation/validation function f. If f returns None, the match is unsuccessful; if f returns a Some, the value inside is the result of the match.

    B

    The transformed context type

    f

    The transformation/validation function

    returns

    A new matcher with transformed and validated results

  19. final def getClass(): Class[_ <: AnyRef]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  20. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  21. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  22. def map[B](f: (A) => B): ContextMatcher[Elem, B]

    Create a new ContextMatcher which takes the match result of this matcher and passes it through the transformation function f.

    Create a new ContextMatcher which takes the match result of this matcher and passes it through the transformation function f.

    B

    The transformed context type

    f

    The transformation function

    returns

    A new matcher with transformed results

  23. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  24. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  25. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  26. def or[A2 >: A](that: ContextMatcher[Elem, A2]): ContextMatcher[Elem, A2]

    Create a new ContextMatcher which will fall back to a second matcher in the event that this matcher fails to match a context.

    Create a new ContextMatcher which will fall back to a second matcher in the event that this matcher fails to match a context.

    A2

    The resulting context type (common supertype between this matcher and that)

    that

    The matcher which will be used as the fallback

    returns

    A matcher that falls back to another matcher in case of failure

  27. final def synchronized[T0](arg0: => T0): T0
    Definition Classes
    AnyRef
  28. def toString(): String
    Definition Classes
    AnyRef → Any
  29. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  30. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  31. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException]) @native()
  32. def |[A2 >: A](that: ContextMatcher[Elem, A2]): ContextMatcher[Elem, A2]

    Operator version of or

Deprecated Value Members

  1. def formatted(fmtstr: String): String
    Implicit
    This member is added by an implicit conversion from ContextMatcher[Elem, A] toStringFormat[ContextMatcher[Elem, A]] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @deprecated @inline()
    Deprecated

    (Since version 2.12.16) Use formatString.format(value) instead of value.formatted(formatString), or use the f"" string interpolator. In Java 15 and later, formatted resolves to the new method in String which has reversed parameters.

  2. def [B](y: B): (ContextMatcher[Elem, A], B)
    Implicit
    This member is added by an implicit conversion from ContextMatcher[Elem, A] toArrowAssoc[ContextMatcher[Elem, A]] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @deprecated
    Deprecated

    (Since version 2.13.0) Use -> instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion any2stringadd fromContextMatcher[Elem, A] to any2stringadd[ContextMatcher[Elem, A]]

Inherited by implicit conversion StringFormat fromContextMatcher[Elem, A] to StringFormat[ContextMatcher[Elem, A]]

Inherited by implicit conversion Ensuring fromContextMatcher[Elem, A] to Ensuring[ContextMatcher[Elem, A]]

Inherited by implicit conversion ArrowAssoc fromContextMatcher[Elem, A] to ArrowAssoc[ContextMatcher[Elem, A]]

Ungrouped