Swish.RDF.Graph

This module defines a memory-based RDF graph instance.

Labels

data RDFLabel

RDF graph node values

cf. http://www.w3.org/TR/rdf-concepts/#section-Graph-syntax

This is extended from the RDF abstract graph syntax in the following ways:

(a) a graph can be part of a resource node or blank node (cf. Notation3 formulae)

(b) a "variable" node option is distinguished from a blank node. I have found this useful for encoding and handling queries, even though query variables can be expressed as blank nodes.

(c) a "NoNode" option is defined. This might otherwise be handled by Maybe (RDFLabel g).

Prior to version 0.7.0.0, literals were represented by a single constructor, Lit, with an optional argument. Language codes for literals was also stored as a ScopedName rather than as a LanguageTag.

Constructors

Res ScopedName

resource

Lit Text

plain literal (http://www.w3.org/TR/rdf-concepts/#dfn-plain-literal)

LangLit Text LanguageTag

plain literal

TypedLit Text ScopedName

typed literal (http://www.w3.org/TR/rdf-concepts/#dfn-typed-literal)

Blank String

blank node

Var String

variable (not used in ordinary graphs)

NoNode

no node (not used in ordinary graphs)

Instances

Eq RDFLabel

Define equality of nodes possibly based on different graph types.

The equality of literals is taken from section 6.5.1 (Literal Equality) of the RDF Concepts and Abstract Document, http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/#section-Literal-Equality.

Ord RDFLabel

Show RDFLabel

IsString RDFLabel

Label RDFLabel

ShowLines RDFGraph

FromRDFLabel RDFLabel

This is just Just . id.

ToRDFLabel RDFLabel

This is just id.

class ToRDFLabel a where

A type that can be converted to a RDF Label.

The String instance converts to an untyped literal (so no language tag is assumed).

The UTCTime and Day instances assume values are in UTC.

The conversion for XSD types attempts to use the canonical form described in section 2.3.1 of http://www.w3.org/TR/2004/REC-xmlschema-2-20041028/#lexical-space.

Note that this is similar to toRDFLabel; the code should probably be combined at some point.

Methods

toRDFLabel :: a -> RDFLabel

Instances

ToRDFLabel Bool

Converts to a literal with a xsd:boolean datatype.

ToRDFLabel Char

The character is converted to an untyped literal of length one.

ToRDFLabel Double

Converts to a literal with a xsd:double datatype.

ToRDFLabel Float

Converts to a literal with a xsd:float datatype.

ToRDFLabel Int

Converts to a literal with a xsd:integer datatype.

ToRDFLabel Integer

Converts to a literal with a xsd:integer datatype.

ToRDFLabel String

Strings are converted to untyped literals.

ToRDFLabel URI

Converts to a Resource.

ToRDFLabel UTCTime

Converts to a literal with a xsd:datetime datatype.

ToRDFLabel Day

Converts to a literal with a xsd:date datatype.

ToRDFLabel QName

Converts to a Resource.

ToRDFLabel ScopedName

Converts to a Resource.

ToRDFLabel RDFLabel

This is just id.

class FromRDFLabel a where

A type that can be converted from a RDF Label, with the possibility of failure.

The String instance converts from an untyped literal (so it can not be used with a string with a language tag).

The following conversions are supported for common XSD types (out-of-band values result in Nothing):

• xsd:boolean to Bool
• xsd:integer to Int and Integer
• xsd:float to Float
• xsd:double to Double
• xsd:dateTime to UTCTime
• xsd:date to Day

Note that this is similar to fromRDFLabel; the code should probably be combined at some point.

Methods

fromRDFLabel :: RDFLabel -> Maybe a

Instances

FromRDFLabel Bool

Converts from a literal with a xsd:boolean datatype. The literal can be any of the supported XSD forms - e.g. "0" or "true".

FromRDFLabel Char

The label must be an untyped literal containing a single character.

FromRDFLabel Double

Converts from a literal with a xsd:double datatype.

FromRDFLabel Float

Converts from a literal with a xsd:float datatype. The conversion will fail if the value is outside the valid range of a Haskell Float.

FromRDFLabel Int

Converts from a literal with a xsd:integer datatype. The conversion will fail if the value is outside the valid range of a Haskell Int.

FromRDFLabel Integer

Converts from a literal with a xsd:integer datatype.

FromRDFLabel String

Only untyped literals are converted to strings.

FromRDFLabel URI

Converts from a Resource.

FromRDFLabel UTCTime

Converts from a literal with a xsd:datetime datatype.

FromRDFLabel Day

Converts from a literal with a xsd:date datatype.

FromRDFLabel QName

Converts from a Resource.

FromRDFLabel ScopedName

Converts from a Resource.

FromRDFLabel RDFLabel

This is just Just . id.

isLiteral :: RDFLabel -> Bool

Test if supplied labal is a literal node (Lit, LangLit, or TypedLit).

isUntypedLiteral :: RDFLabel -> Bool

Test if supplied labal is an untyped literal node (either Lit or LangLit).

isTypedLiteral :: RDFLabel -> Bool

Test if supplied labal is a typed literal node (TypedLit).

isXMLLiteral :: RDFLabel -> Bool

Test if supplied labal is a XML literal node

isDatatyped :: ScopedName -> RDFLabel -> Bool

Test if supplied label is a typed literal node of a given datatype

isMemberProp :: RDFLabel -> Bool

Test if supplied label is a container membership property

Check for namespace is RDF namespace and first character of local name is '_' and remaining characters of local name are all digits

isUri :: RDFLabel -> Bool

Test if supplied labal is a URI resource node

isBlank :: RDFLabel -> Bool

Test if supplied labal is a blank node

isQueryVar :: RDFLabel -> Bool

Test if supplied labal is a query variable

getLiteralText :: RDFLabel -> Text

Extract text value from a literal node (including the Language and Typed variants). The empty string is returned for other nodes.

getScopedName :: RDFLabel -> ScopedName

Extract the ScopedName value from a resource node (nullScopedName is returned for non-resource nodes).

makeBlank :: RDFLabel -> RDFLabel

Make a blank node from a supplied query variable, or return the supplied label unchanged. (Use this in when substituting an existential for an unsubstituted query variable.)

quote

Arguments

:: Bool

True if the string is to be displayed using one rather than three quotes.

-> String

String to quote.

-> String

N3-style quoting rules for a string.

TODO: when flag is False need to worry about multiple quotes (> 2) in a row.

quoteT :: Bool -> Text -> Text

See quote.

RDF Graphs

type RDFArcSet = ArcSet RDFLabel

A set of RDF triples.

type RDFTriple = Arc RDFLabel

RDF Triple (statement)

At present there is no check or type-level constraint that stops the subject or predicate of the triple from being a literal.

toRDFTriple

Arguments

:: (ToRDFLabel s, ToRDFLabel p, ToRDFLabel o)

=> s

Subject

-> p

Predicate

-> o

Object

-> RDFTriple

Convert 3 RDF labels to a RDF triple.

See also Swish.RDF.GraphClass.arcFromTriple.

fromRDFTriple

Arguments

:: (FromRDFLabel s, FromRDFLabel p, FromRDFLabel o)

=> RDFTriple

-> Maybe (s, p, o)

The conversion only succeeds if all three components can be converted to the correct Haskell types.

Extract the contents of a RDF triple.

See also Swish.RDF.GraphClass.arcToTriple.

data NSGraph lb

Memory-based graph with namespaces and subgraphs.

The primary means for adding arcs to an existing graph are:

• setArcs from the LDGraph instance, which replaces the existing set of arcs and does not change the namespace map.
• addArc which checks that the arc is unknown before adding it but does not change the namespace map or re-label any blank nodes in the arc.

Constructors

NSGraph

Fields

namespaces :: NamespaceMap

the namespaces to use

formulae :: FormulaMap lb

any associated formulae (a.k.a. sub- or named- graps)

statements :: ArcSet lb

the statements in the graph

Instances

ShowLines RDFGraph

Label lb => LDGraph NSGraph lb

Label lb => Eq (NSGraph lb)

Label lb => Ord (NSGraph lb)

Label lb => Show (NSGraph lb)

Label lb => Show (Formula lb)

Label lb => Monoid (NSGraph lb)

The mappend operation uses merge rather than addGraphs.

type RDFGraph = NSGraph RDFLabel

Memory-based RDF graph type

toRDFGraph :: RDFArcSet -> RDFGraph

Create a new RDF graph from a supplied set of arcs.

This version will attempt to fill up the namespace map of the graph based on the input labels (including datatypes on literals). For faster creation of a graph you can use:

 emptyRDFGraph { statements = arcs }

which is how this routine was defined in version 0.3.1.1 and earlier.

emptyRDFGraph :: RDFGraph

Create a new, empty RDF graph (it is just mempty).

type NamespaceMap = Map (Maybe Text) URI

Namespace prefix list entry

A map for name spaces (key is the prefix).

emptyNamespaceMap :: NamespaceMap

Create an empty namespace map.

data LookupFormula lb gr

Graph formula entry

Constructors

Formula

Fields

formLabel :: lb

The label for the formula

formGraph :: gr

The contents of the formula

Instances

Label lb => Show (Formula lb)

(Eq lb, Eq gr) => Eq (LookupFormula lb gr)

(Ord lb, Ord gr) => Ord (LookupFormula lb gr)

type Formula lb = LookupFormula lb (NSGraph lb)

A named formula.

type FormulaMap lb = Map lb (NSGraph lb)

A map for named formulae.

emptyFormulaMap :: FormulaMap RDFLabel

Create an empty formula map.

addArc :: Label lb => Arc lb -> NSGraph lb -> NSGraph lb

Add an arc to the graph. It does not relabel any blank nodes in the input arc, nor does it change the namespace map, but it does ensure that the arc is unknown before adding it.

merge :: Label lb => NSGraph lb -> NSGraph lb -> NSGraph lb

Merge RDF graphs, renaming blank and query variable nodes as needed to neep variable nodes from the two graphs distinct in the resulting graph.

Currently formulae are not guaranteed to be preserved across a merge.

allLabels :: Label lb => (lb -> Bool) -> NSGraph lb -> Set lb

Return list of all labels (including properties) in the graph satisfying a supplied filter predicate. This routine includes the labels in any formulae.

allNodes :: Label lb => (lb -> Bool) -> NSGraph lb -> Set lb

Return list of all subjects and objects in the graph satisfying a supplied filter predicate.

remapLabels

Arguments

:: Label lb

=> [lb]

variable nodes to be renamed (dupbn)

-> [lb]

variable nodes used that must be avoided (allbn)

-> (lb -> lb)

node conversion function that is applied to nodes from dupbn in the graph that are to be replaced by new blank nodes. If no such conversion is required, supply id. The function makeBlank can be used to convert RDF query nodes into RDF blank nodes.

-> NSGraph lb

graph in which nodes are to be renamed

-> NSGraph lb

Remap selected nodes in graph.

This is the node renaming operation that prevents graph-scoped variable nodes from being merged when two graphs are merged.

remapLabelList

Arguments

:: Label lb

=> [lb]

labels to be remaped

-> [lb]

labels to be avoided by the remapping

-> [(lb, lb)]

Externally callable function to construct a list of (old,new) values to be used for graph label remapping.

newNode :: Label lb => lb -> [lb] -> lb

Given a node and a list of existing nodes, find a new node for the supplied node that does not clash with any existing node. (Generates an non-terminating list of possible replacements, and picks the first one that isn't already in use.)

TODO: optimize this for common case nnn and _nnn: always generate _nnn and keep track of last allocated

newNodes :: Label lb => lb -> [lb] -> [lb]

Given a node and a list of existing nodes, generate a list of new nodes for the supplied node that do not clash with any existing node.

setNamespaces :: NamespaceMap -> NSGraph lb -> NSGraph lb

Replace the namespace information in the graph.

getNamespaces :: NSGraph lb -> NamespaceMap

Retrieve the namespace map in the graph.

setFormulae :: FormulaMap lb -> NSGraph lb -> NSGraph lb

Replace the formulae in the graph.

getFormulae :: NSGraph lb -> FormulaMap lb

Retrieve the formulae in the graph.

setFormula :: Label lb => Formula lb -> NSGraph lb -> NSGraph lb

Add (or replace) a formula.

getFormula :: Label lb => NSGraph lb -> lb -> Maybe (NSGraph lb)

Find a formula in the graph, if it exists.

fmapNSGraph :: Ord lb => (lb -> lb) -> NSGraph lb -> NSGraph lb

fmap for NSGraph instances.

traverseNSGraph :: (Applicative f, Ord a) => (a -> f a) -> NSGraph a -> f (NSGraph a)

traverse for NSGraph instances.

Re-export from GraphClass

Note that asubj, apred and aobj have been removed in version 0.7.0.0; use arcSubj, arcPred or arcObj instead.

class LDGraph lg lb where

Labelled Directed Graph class.

Minimum required implementation: emptyGraph, setArcs, and getArcs.

Methods

emptyGraph :: lg lb

Create the empty graph.

setArcs :: lg lb -> ArcSet lb -> lg lb

Replace the existing arcs in the graph.

getArcs :: lg lb -> ArcSet lb

Extract all the arcs from a graph

extract :: Ord lb => Selector lb -> lg lb -> lg lb

Extract those arcs that match the given Selector.

addGraphs :: Ord lb => lg lb -> lg lb -> lg lb

Add the two graphs

delete

Arguments

:: Ord lb

=> lg lb

g1

-> lg lb

g2

-> lg lb

g2 - g1 -> g3

Remove those arcs in the first graph from the second graph

labels :: Ord lb => lg lb -> Set lb

Enumerate the distinct labels contained in a graph; that is, any label that appears in the subject, predicate or object position of an Arc.

nodes :: Ord lb => lg lb -> Set lb

Enumerate the distinct nodes contained in a graph; that is, any label that appears in the subject or object position of an Arc.

update :: (ArcSet lb -> ArcSet lb) -> lg lb -> lg lb

Update the arcs in a graph using a supplied function.

Instances

Label lb => LDGraph GraphMem lb

Label lb => LDGraph NSGraph lb

class (Ord lb, Show lb) => Label lb where

Label class.

A label may have a fixed binding, which means that the label identifies (is) a particular graph node, and different such labels are always distinct nodes. Alternatively, a label may be unbound (variable), which means that it is a placeholder for an unknown node label. Unbound node labels are used as graph-local identifiers for indicating when the same node appears in several arcs.

For the purposes of graph-isomorphism testing, fixed labels are matched when they are the same. Variable labels may be matched with any other variable label. Our definition of isomorphism (for RDF graphs) does not match variable labels with fixed labels.

Methods

labelIsVar :: lb -> Bool

Does this node have a variable binding?

labelHash :: Int -> lb -> Int

Calculate the hash of the label using the supplied seed.

getLocal :: lb -> String

Extract the local id from a variable node.

makeLabel :: String -> lb

Make a label value from a local id.

Instances

Label LabelMem

Label RDFLabel

Label lb => Label (ScopedLabel lb)

data Arc lb

Arc type.

Prior to 0.7.0.0 you could also use asubj, apred and aobj to access the elements of the arc.

Constructors

Arc

Fields

arcSubj :: lb

The subject of the arc.

arcPred :: lb

The predicate (property) of the arc.

arcObj :: lb

The object of the arc.

Instances

Functor Arc

Foldable Arc

Traversable Arc

Eq lb => Eq (Arc lb)

Ord lb => Ord (Arc lb)

Show lb => Show (Arc lb)

Hashable lb => Hashable (Arc lb)

arc

Arguments

:: lb

The subject of the arc.

-> lb

The predicate of the arc.

-> lb

The object of the arc.

-> Arc lb

Create an arc.

type Selector lb = Arc lb -> Bool

Identify arcs.

Selected RDFLabel values

The ToRDFLabel instance of ScopedName can also be used to easily construct RDFLabel versions of the terms defined in Swish.RDF.Vocabulary.

RDF terms

These terms are described in http://www.w3.org/TR/rdf-syntax-grammar/; the version used is "W3C Recommendation 10 February 2004", http://www.w3.org/TR/2004/REC-rdf-syntax-grammar-20040210/.

Some terms are listed within the RDF Schema terms below since their definition is given within the RDF Schema document.

resRdfRDF :: RDFLabel

rdf:RDF.

resRdfDescription :: RDFLabel

rdf:Description.

resRdfID :: RDFLabel

rdf:ID.

resRdfAbout :: RDFLabel

rdf:about.

resRdfParseType :: RDFLabel

rdf:parseType.

resRdfResource :: RDFLabel

rdf:resource.

resRdfLi :: RDFLabel

rdf:li.

resRdfNodeID :: RDFLabel

rdf:nodeID.

resRdfDatatype :: RDFLabel

rdf:datatype.

resRdf1 :: RDFLabel

rdf:_1.

resRdf2 :: RDFLabel

rdf:_2.

resRdfn :: Word32 -> RDFLabel

Create a rdf:_n entity.

There is no check that the argument is not 0.

RDF Schema terms

These are defined by http://www.w3.org/TR/rdf-schema/; the version used is "W3C Recommendation 10 February 2004", http://www.w3.org/TR/2004/REC-rdf-schema-20040210/.

Classes

See the "Classes" section at http://www.w3.org/TR/rdf-schema/#ch_classes for more information.

resRdfsResource :: RDFLabel

rdfs:Resource from http://www.w3.org/TR/rdf-schema/#ch_resource.

resRdfsClass :: RDFLabel

rdfs:Class from http://www.w3.org/TR/rdf-schema/#ch_class.

resRdfsLiteral :: RDFLabel

rdfs:Literal from http://www.w3.org/TR/rdf-schema/#ch_literal.

resRdfsDatatype :: RDFLabel

rdfs:Datatype from http://www.w3.org/TR/rdf-schema/#ch_datatype.

resRdfXMLLiteral :: RDFLabel

rdf:XMLLiteral from http://www.w3.org/TR/rdf-schema/#ch_xmlliteral.

resRdfProperty :: RDFLabel

rdf:Property from http://www.w3.org/TR/rdf-schema/#ch_property.

Properties

See the "Properties" section at http://www.w3.org/TR/rdf-schema/#ch_classes for more information.

resRdfsRange :: RDFLabel

rdfs:range from http://www.w3.org/TR/rdf-schema/#ch_range.

resRdfsDomain :: RDFLabel

rdfs:domain from http://www.w3.org/TR/rdf-schema/#ch_domain.

resRdfType :: RDFLabel

rdf:type from http://www.w3.org/TR/rdf-schema/#ch_type.

resRdfsSubClassOf :: RDFLabel

rdfs:subClassOf from http://www.w3.org/TR/rdf-schema/#ch_subclassof.

resRdfsSubPropertyOf :: RDFLabel

rdfs:subPropertyOf from http://www.w3.org/TR/rdf-schema/#ch_subpropertyof.

resRdfsLabel :: RDFLabel

rdfs:label from http://www.w3.org/TR/rdf-schema/#ch_label.

resRdfsComment :: RDFLabel

rdfs:comment from http://www.w3.org/TR/rdf-schema/#ch_comment.

Containers

See the "Container Classes and Properties" section at http://www.w3.org/TR/rdf-schema/#ch_containervocab.

resRdfsContainer :: RDFLabel

rdfs:Container from http://www.w3.org/TR/rdf-schema/#ch_container.

resRdfBag :: RDFLabel

rdf:Bag from http://www.w3.org/TR/rdf-schema/#ch_bag.

resRdfSeq :: RDFLabel

rdf:Seq from http://www.w3.org/TR/rdf-schema/#ch_seq.

resRdfAlt :: RDFLabel

rdf:Alt from http://www.w3.org/TR/rdf-schema/#ch_alt.

resRdfsContainerMembershipProperty :: RDFLabel

rdfs:ContainerMembershipProperty from http://www.w3.org/TR/rdf-schema/#ch_containermembershipproperty.

resRdfsMember :: RDFLabel

rdfs:member from http://www.w3.org/TR/rdf-schema/#ch_member.

Collections

See the "Collections" section at http://www.w3.org/TR/rdf-schema/#ch_collectionvocab.

resRdfList :: RDFLabel

rdf:List from http://www.w3.org/TR/rdf-schema/#ch_list.

resRdfFirst :: RDFLabel

rdf:first from http://www.w3.org/TR/rdf-schema/#ch_first.

resRdfRest :: RDFLabel

rdf:rest from http://www.w3.org/TR/rdf-schema/#ch_rest.

resRdfNil :: RDFLabel

rdf:nil from http://www.w3.org/TR/rdf-schema/#ch_nil.

Reification Vocabulary

See the "Reification Vocabulary" section at http://www.w3.org/TR/rdf-schema/#ch_reificationvocab.

resRdfStatement :: RDFLabel

rdf:Statement from http://www.w3.org/TR/rdf-schema/#ch_statement.

resRdfSubject :: RDFLabel

rdf:subject from http://www.w3.org/TR/rdf-schema/#ch_subject.

resRdfPredicate :: RDFLabel

rdf:predicate from http://www.w3.org/TR/rdf-schema/#ch_predicate.

resRdfObject :: RDFLabel

rdf:object from http://www.w3.org/TR/rdf-schema/#ch_object.

Utility Properties

See the "Utility Properties" section at http://www.w3.org/TR/rdf-schema/#ch_utilvocab.

resRdfsSeeAlso :: RDFLabel

rdfs:seeAlso from http://www.w3.org/TR/rdf-schema/#ch_seealso.

resRdfsIsDefinedBy :: RDFLabel

rdfs:isDefinedBy from http://www.w3.org/TR/rdf-schema/#ch_isdefinedby.

resRdfValue :: RDFLabel

rdf:value from http://www.w3.org/TR/rdf-schema/#ch_value.

OWL

resOwlSameAs :: RDFLabel

owl:sameAs.

Miscellaneous

resRdfdGeneralRestriction :: RDFLabel

rdfd:GeneralRestriction.

resRdfdOnProperties :: RDFLabel

rdfd:onProperties.

resRdfdConstraint :: RDFLabel

rdfd:constraint.

resRdfdMaxCardinality :: RDFLabel

rdfd:maxCardinality.

resLogImplies :: RDFLabel

log:implies.

Exported for testing

grMatchMap :: Label lb => NSGraph lb -> NSGraph lb -> (Bool, LabelMap (ScopedLabel lb))

Match graphs, returning True if they are equivalent, with a map of labels to equivalence class identifiers (see graphMatch for further details).

grEq :: Label lb => NSGraph lb -> NSGraph lb -> Bool

Graph equality.

mapnode :: Label lb => [lb] -> [lb] -> (lb -> lb) -> lb -> lb

Remap a single graph node.

If the node is not one of those to be remapped, the supplied value is returned unchanged.

maplist

Arguments

:: Label lb

=> [lb]

oldnode values

-> [lb]

nodes to be avoided

-> (lb -> lb)

-> [(lb, lb)]

accumulator

-> [(lb, lb)]

Construct a list of (oldnode,newnode) values to be used for graph label remapping. The function operates recursively, adding new nodes generated to the accumulator and also to the list of nodes to be avoided.