quad

package module
Version: v1.2.4 Latest Latest
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Published: Apr 4, 2020 License: Apache-2.0 Imports: 15 Imported by: 92

README

Quad formats for Go

Build Status

This library provides encoding and decoding support for NQuad/NTriple-compatible formats.

Supported formats

ID Name Read Write Ext
nquads NQuads + + .nq, .nt
jsonld JSON-LD + + .jsonld
graphviz DOT/Graphviz - + .gv, .dot
gml GML - + .gml
graphml GraphML - + .graphml
pquads ProtoQuads + + .pq
json JSON + + .json
json-stream JSON Stream + + -

Community

Documentation

Overview

Package quad defines quad and triple handling.

Index

Constants

View Source
const (
	// IRIDefault preserves current IRI formatting.
	IRIDefault = IRIFormat(iota)
	// IRIShort changes IRI to use a short namespace prefix (ex: <rdf:type>).
	IRIShort
	// IRIFull changes IRI to use full form (ex: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>).
	IRIFull
)
View Source
const HashSize = sha1.Size

HashSize is a size of the slice, returned by HashOf.

Variables

View Source
var (
	ErrInvalid    = errors.New("invalid N-Quad")
	ErrIncomplete = errors.New("incomplete N-Quad")
)
View Source
var DefaultBatch = 10000
View Source
var KnownBoolTypes = []IRI{
	defaultBoolType,
	schema.Boolean,
}

KnownBoolTypes consists of known IRIs of boolean types

View Source
var KnownFloatTypes = []IRI{
	defaultFloatType,
	xsd.Float,
	schema.Float,
	schema.Number,
}

KnownFloatTypes consists of known IRIs of floating-point numbers types

View Source
var KnownIntTypes = []IRI{
	defaultIntType,
	xsd.Int,
	xsd.Long,
	schema.Integer,
}

KnownIntTypes consists of known IRIs of integer types

View Source
var KnownTimeTypes = []IRI{
	defaultTimeType,
	xsd.DateTime,
	schema.DateTime,
}

KnownTimeTypes consists of known IRIs of datetime types

Functions

func Copy

func Copy(dst Writer, src Reader) (n int, err error)

Copy will copy all quads from src to dst. It returns copied quads count and an error, if it failed.

Copy will try to cast dst to BatchWriter and will switch to CopyBatch implementation in case of success.

func CopyBatch

func CopyBatch(dst BatchWriter, src Reader, batchSize int) (cnt int, err error)

CopyBatch will copy all quads from src to dst in a batches of batchSize. It returns copied quads count and an error, if it failed.

If batchSize <= 0 default batch size will be used.

func HasStringConversion added in v1.2.2

func HasStringConversion(dataType IRI) bool

HasStringConversion returns whether IRI has a string conversion

func HashOf

func HashOf(v Value) []byte

HashOf calculates a hash of value v.

func HashTo

func HashTo(v Value, p []byte)

HashTo calculates a hash of value v, storing it in a slice p.

func IsValidValue

func IsValidValue(v Value) bool

IsValidValue checks if the value is valid. It returns false if the value is nil, an empty IRI or an empty BNode.

func NativeOf

func NativeOf(v Value) interface{}

NativeOf safely call v.Native, returning nil in case of nil Value.

func RegisterFormat

func RegisterFormat(f Format)

RegisterFormat registers a new quad-file format.

func RegisterStringConversion

func RegisterStringConversion(dataType IRI, fnc StringConversion)

RegisterStringConversion will register an automatic conversion of TypedString values with provided type to a native equivalent such as Int, Time, etc.

If fnc is nil, automatic conversion from selected type will be removed.

func RegisterStringConversions added in v1.2.2

func RegisterStringConversions(dataTypes []IRI, fnc StringConversion)

RegisterStringConversions calls RegisterStringConversion with every IRI in dataTypes and fnc

func StringOf

func StringOf(v Value) string

StringOf safely call v.String, returning empty string in case of nil Value.

func ToString

func ToString(v Value) string

ToString casts a values to String or falls back to StringOf.

Types

type BNode

type BNode string

BNode is an RDF Blank Node (ex: _:name).

func RandomBlankNode

func RandomBlankNode() BNode

RandomBlankNode returns a randomly generated Blank Node.

func (BNode) GoString

func (s BNode) GoString() string

func (BNode) Native

func (s BNode) Native() interface{}

func (BNode) String

func (s BNode) String() string

type BatchReader

type BatchReader interface {
	ReadQuads(buf []Quad) (int, error)
}

BatchReader is an interface for reading quads in batches.

ReadQuads reads at most len(buf) quads into buf. It returns number of quads that were read and an error. It returns an io.EOF if there is no more quads to read.

type BatchWriter

type BatchWriter interface {
	// WriteQuads returns a number of quads that where written and an error, if any.
	WriteQuads(buf []Quad) (int, error)
}

BatchWriter is an interface for writing quads in batches.

type Bool

type Bool bool

Bool is a native wrapper for bool type.

It uses NQuad notation similar to TypedString.

func (Bool) Native

func (s Bool) Native() interface{}

func (Bool) String

func (s Bool) String() string

func (Bool) TypedString

func (s Bool) TypedString() TypedString

type ByQuadString

type ByQuadString []Quad

func (ByQuadString) Len

func (o ByQuadString) Len() int

func (ByQuadString) Less

func (o ByQuadString) Less(i, j int) bool

func (ByQuadString) Swap

func (o ByQuadString) Swap(i, j int)

type ByValueString

type ByValueString []Value

func (ByValueString) Len

func (o ByValueString) Len() int

func (ByValueString) Less

func (o ByValueString) Less(i, j int) bool

func (ByValueString) Swap

func (o ByValueString) Swap(i, j int)

type Direction

type Direction byte

Direction specifies an edge's type.

const (
	Any Direction = iota
	Subject
	Predicate
	Object
	Label
)

List of the valid directions of a quad.

func (Direction) GoString

func (d Direction) GoString() string

func (Direction) Prefix

func (d Direction) Prefix() byte

func (Direction) String

func (d Direction) String() string

type Equaler

type Equaler interface {
	Equal(v Value) bool
}

Equaler interface is implemented by values, that needs a special equality check.

type Float

type Float float64

Float is a native wrapper for float64 type.

It uses NQuad notation similar to TypedString.

func (Float) Native

func (s Float) Native() interface{}

func (Float) String

func (s Float) String() string

func (Float) TypedString

func (s Float) TypedString() TypedString

type Format

type Format struct {
	// Name is a short format name used as identifier for RegisterFormat.
	Name string
	// Ext is a list of file extensions, allowed for file format. Can be used to detect file format, given a path.
	Ext []string
	// Mime is a list of MIME (content) types, allowed for file format. Can be used in HTTP request/responses.
	Mime []string
	// Reader is a function for creating format reader, that reads serialized data from io.Reader.
	Reader func(io.Reader) ReadCloser
	// Writer is a function for creating format writer, that streams serialized data to io.Writer.
	Writer func(io.Writer) WriteCloser
	// Binary is set to true if format is not human-readable.
	Binary bool
	// MarshalValue encodes one value in specific a format.
	MarshalValue func(v Value) ([]byte, error)
	// UnmarshalValue decodes a value from specific format.
	UnmarshalValue func(b []byte) (Value, error)
}

Format is a description for quad-file formats.

func FormatByExt

func FormatByExt(name string) *Format

FormatByExt returns a registered format by its file extension. Will return nil if format is not found.

func FormatByMime

func FormatByMime(name string) *Format

FormatByMime returns a registered format by its MIME type. Will return nil if format is not found.

func FormatByName

func FormatByName(name string) *Format

FormatByName returns a registered format by its name. Will return nil if format is not found.

func Formats

func Formats() []Format

Formats returns a list of all supported quad formats.

type IRI

type IRI string

IRI is an RDF Internationalized Resource Identifier (ex: <name>).

func (IRI) Format

func (s IRI) Format(format IRIFormat) IRI

Format the IRI according to selection.

func (IRI) Full

func (s IRI) Full() IRI

Full uses voc package to convert a short namespace prefix (if any) to a full IRI prefix. The prefix must be registered in the voc package.

func (IRI) FullWith

func (s IRI) FullWith(n *voc.Namespaces) IRI

FullWith uses provided namespace to convert a short namespace prefix (if any) to a full IRI prefix.

func (IRI) GoString

func (s IRI) GoString() string

GoString overrides IRI's %#v printing behaviour to include the type name.

func (IRI) Native

func (s IRI) Native() interface{}

Native returns an IRI value unchanged (to not collide with String values).

func (IRI) Short

func (s IRI) Short() IRI

Short uses voc package to convert a full IRI prefix (if any) to a short namespace prefix. The prefix must be registered in the voc package.

func (IRI) ShortWith

func (s IRI) ShortWith(n *voc.Namespaces) IRI

ShortWith uses the provided namespace to convert a full IRI prefix (if any) to a short namespace prefix.

func (IRI) String

func (s IRI) String() string

String prints IRI in "<iri>" form.

type IRIFormat

type IRIFormat int

IRIFormat is a format of IRI.

type IRIOptions

type IRIOptions struct {
	Format IRIFormat // short vs full IRI format
	// Func is executed after all other options and have a chance to replace the value.
	// Returning an empty IRI changes the value to nil.
	Func func(d Direction, iri IRI) (IRI, error)
}

IRIOptions is a set of option

type Identifier added in v1.2.0

type Identifier interface {
	Value
	// contains filtered or unexported methods
}

Identifier is a union of IRI and BNode.

type Int

type Int int64

Int is a native wrapper for int64 type.

It uses NQuad notation similar to TypedString.

func (Int) Native

func (s Int) Native() interface{}

func (Int) String

func (s Int) String() string

func (Int) TypedString

func (s Int) TypedString() TypedString

type LangString

type LangString struct {
	Value String
	Lang  string
}

LangString is an RDF string with language (ex: "name"@lang).

func (LangString) Native

func (s LangString) Native() interface{}

func (LangString) String

func (s LangString) String() string

type Quad

type Quad struct {
	Subject   Value `json:"subject"`
	Predicate Value `json:"predicate"`
	Object    Value `json:"object"`
	Label     Value `json:"label,omitempty"`
}

Our quad struct, used throughout.

func Make

func Make(subject, predicate, object, label interface{}) (q Quad)

Make creates a quad with provided values.

func MakeIRI

func MakeIRI(subject, predicate, object, label string) (q Quad)

MakeIRI creates a quad with provided IRI values.

func MakeRaw deprecated

func MakeRaw(subject, predicate, object, label string) (q Quad)

MakeRaw creates a quad with provided raw values (nquads-escaped).

Deprecated: use Make pr MakeIRI instead.

func ReadAll

func ReadAll(r Reader) (arr []Quad, err error)

ReadAll reads all quads from r until EOF. It returns a slice with all quads that were read and an error, if any.

func (Quad) Get

func (q Quad) Get(d Direction) Value

Per-field accessor for quads.

func (Quad) GetString

func (q Quad) GetString(d Direction) string

Per-field accessor for quads that returns strings instead of values.

func (Quad) IsValid

func (q Quad) IsValid() bool

func (Quad) MarshalJSON

func (q Quad) MarshalJSON() ([]byte, error)

func (Quad) NQuad

func (q Quad) NQuad() string

Prints a quad in N-Quad format.

func (*Quad) Set

func (q *Quad) Set(d Direction, v Value)

func (Quad) String

func (q Quad) String() string

Pretty-prints a quad.

func (*Quad) UnmarshalJSON

func (q *Quad) UnmarshalJSON(data []byte) error

type Quads

type Quads struct {
	// contains filtered or unexported fields
}

func NewReader

func NewReader(quads []Quad) *Quads

NewReader creates a quad reader from a quad slice.

func (*Quads) ReadQuad

func (r *Quads) ReadQuad() (Quad, error)

func (*Quads) WriteQuad

func (r *Quads) WriteQuad(q Quad) error

type ReadCloser

type ReadCloser interface {
	Reader
	io.Closer
}

type ReadSkipCloser

type ReadSkipCloser interface {
	Reader
	Skipper
	io.Closer
}

type Reader

type Reader interface {
	ReadQuad() (Quad, error)
}

Reader is a minimal interface for quad readers. Used for quad deserializers and quad iterators.

ReadQuad reads next valid Quad. It returns io.EOF if no quads are left.

type Sequence

type Sequence struct {
	// contains filtered or unexported fields
}

Sequence is an object to generate a sequence of Blank Nodes.

func (*Sequence) Next

func (s *Sequence) Next() BNode

Next returns a new blank node. It's safe for concurrent use.

type Skipper

type Skipper interface {
	SkipQuad() error
}

Skipper is an interface for quad reader that can skip quads efficiently without decoding them.

It returns io.EOF if no quads are left.

type String

type String string

String is an RDF string value (ex: "name").

func (String) GoString

func (s String) GoString() string

func (String) Native

func (s String) Native() interface{}

func (String) String

func (s String) String() string

type StringConversion

type StringConversion func(string) (Value, error)

StringConversion is a function to convert string values with a specific IRI type to their native equivalents.

type Time

type Time time.Time

Time is a native wrapper for time.Time type.

It uses NQuad notation similar to TypedString.

func (Time) Equal

func (s Time) Equal(v Value) bool

func (Time) Native

func (s Time) Native() interface{}

func (Time) String

func (s Time) String() string

func (Time) TypedString

func (s Time) TypedString() TypedString

type TypedString

type TypedString struct {
	Value String
	Type  IRI
}

TypedString is an RDF value with type (ex: "name"^^<type>).

func (TypedString) Native

func (s TypedString) Native() interface{}

func (TypedString) ParseValue

func (s TypedString) ParseValue() (Value, error)

ParseValue will try to parse underlying string value using registered functions.

It will return unchanged value if suitable function is not available.

Error will be returned if the type was recognizes, but parsing failed.

func (TypedString) String

func (s TypedString) String() string

type TypedStringer

type TypedStringer interface {
	TypedString() TypedString
}

type Value

type Value interface {
	String() string
	// Native converts Value to a closest native Go type.
	//
	// If type has no analogs in Go, Native return an object itself.
	Native() interface{}
}

Value is a type used by all quad directions.

func AsValue

func AsValue(v interface{}) (out Value, ok bool)

AsValue converts native type into closest Value representation. It returns false if type was not recognized.

func Raw deprecated

func Raw(s string) Value

Raw is a Turtle/NQuads-encoded value.

Deprecated: use IRI or String instead.

func StringToValue

func StringToValue(v string) Value

StringToValue is a function to convert strings to typed quad values.

Warning: should not be used directly - will be deprecated.

type WriteCloser

type WriteCloser interface {
	Writer
	io.Closer
}

type Writer

type Writer interface {
	// WriteQuad writes a single quad and returns an error, if any.
	//
	// Deprecated: use WriteQuads instead.
	WriteQuad(Quad) error
	BatchWriter
}

Writer is a minimal interface for quad writers. Used for quad serializers and quad stores.

func IRIWriter

func IRIWriter(w Writer, opt IRIOptions) Writer

IRIWriter is a writer implementation that converts all IRI values in quads according to the IRIOptions.

func ValuesWriter

func ValuesWriter(w Writer, fnc func(d Direction, v Value) (Value, error)) Writer

ValuesWriter is a writer implementation that converts all quad values using the callback function.

Directories

Path Synopsis
Package dot provides an encoder for DOT format (graphviz).
Package dot provides an encoder for DOT format (graphviz).
Package gml provides an encoder for Graph Modeling Format
Package gml provides an encoder for Graph Modeling Format
Package graphml provides an encoder for GraphML format
Package graphml provides an encoder for GraphML format
Package json provides an encoder/decoder for JSON quad formats
Package json provides an encoder/decoder for JSON quad formats
Package jsonld provides an encoder/decoder for JSON-LD quad format
Package jsonld provides an encoder/decoder for JSON-LD quad format
Package nquads implements parsing the RDF 1.1 N-Quads like line-based syntax for RDF datasets.
Package nquads implements parsing the RDF 1.1 N-Quads like line-based syntax for RDF datasets.
Package pquads implements Cayley-specific protobuf-based quads format.
Package pquads implements Cayley-specific protobuf-based quads format.
pio
voc
Package voc implements an RDF namespace (vocabulary) registry.
Package voc implements an RDF namespace (vocabulary) registry.
core
Package core imports all well-known RDF vocabularies.
Package core imports all well-known RDF vocabularies.
owl
Package owl contains constants of the Web Ontology Language (OWL)
Package owl contains constants of the Web Ontology Language (OWL)
rdf
Package rdf contains constants of the RDF Concepts Vocabulary (RDF)
Package rdf contains constants of the RDF Concepts Vocabulary (RDF)
rdfs
Package rdfs contains constants of the RDF Schema vocabulary (RDFS)
Package rdfs contains constants of the RDF Schema vocabulary (RDFS)
schema
Package schema contains constants of the Schema.org vocabulary.
Package schema contains constants of the Schema.org vocabulary.
xsd
Package xsd contains constants of the W3C XML Schema Definition Language https://www.w3.org/TR/xmlschema11-1/
Package xsd contains constants of the W3C XML Schema Definition Language https://www.w3.org/TR/xmlschema11-1/

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