Swish.RDF.RDFGraph

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).

Constructors

Res ScopedName

resource

Lit String (Maybe ScopedName)

literal [type/language]

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

ShowM RDFGraph

Label RDFLabel

FromRDFLabel RDFLabel

ToRDFLabel RDFLabel

LookupEntryClass NamedGraph ScopedName [RDFGraph]

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 very similar to Swish.RDF.RDFDatatype.toRDFLabel and should be moved into a Swish.RDF.Datatype module.

Methods

toRDFLabel :: a -> RDFLabel

Instances

ToRDFLabel Bool

Converts to a literal with a xsd:boolean datatype.

ToRDFLabel Char

ToRDFLabel Double

ToRDFLabel Float

ToRDFLabel Int

ToRDFLabel Integer

ToRDFLabel String

ToRDFLabel URI

ToRDFLabel UTCTime

ToRDFLabel Day

ToRDFLabel QName

ToRDFLabel ScopedName

ToRDFLabel RDFLabel

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 very similar to Swish.RDF.RDFDatatype.fromRDFLabel and should be moved into a Swish.RDF.Datatype module.

Methods

fromRDFLabel :: RDFLabel -> Maybe a

Instances

FromRDFLabel Bool

Converts from a literal with a xsd:boolean datatype.

FromRDFLabel Char

FromRDFLabel Double

FromRDFLabel Float

FromRDFLabel Int

FromRDFLabel Integer

FromRDFLabel String

FromRDFLabel URI

FromRDFLabel UTCTime

FromRDFLabel Day

FromRDFLabel QName

FromRDFLabel ScopedName

FromRDFLabel RDFLabel

isLiteral :: RDFLabel -> Bool

Test if supplied labal is a literal node

isUntypedLiteral :: RDFLabel -> Bool

Test if supplied labal is an untyped literal node

isTypedLiteral :: RDFLabel -> Bool

Test if supplied labal is an untyped literal node

isXMLLiteral :: RDFLabel -> Bool

Test if supplied labal is an XML literal node

isDatatyped :: ScopedName -> RDFLabel -> Bool

Test if supplied label is an 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 -> String

Extract text value from a literal node

getScopedName :: RDFLabel -> ScopedName

Extract ScopedName value from a resource node

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.)

RDF Graphs

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 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 arcToTriple.

data NSGraph lb

Memory-based graph with namespaces and subgraphs

Constructors

NSGraph

Fields

namespaces :: NamespaceMap

formulae :: FormulaMap lb

statements :: [Arc lb]

Instances

Functor NSGraph

Foldable NSGraph

Traversable NSGraph

ShowM RDFGraph

Label lb => LDGraph NSGraph lb

LookupEntryClass NamedGraph ScopedName [RDFGraph]

Label lb => Eq (NSGraph lb)

Label lb => Show (NSGraph lb)

Label lb => Monoid (NSGraph lb)

Label lb => Show (LookupFormula lb (NSGraph lb))

Label lb => LookupEntryClass (LookupFormula lb (NSGraph lb)) lb (NSGraph lb)

type RDFGraph = NSGraph RDFLabel

Memory-based RDF graph type

toRDFGraph :: [Arc RDFLabel] -> RDFGraph

Create a new RDF graph from a supplied list of arcs

emptyRDFGraph :: RDFGraph

Create a new, empty RDF graph.

type NamespaceMap = LookupMap Namespace

Namespace prefix list entry

type RevNamespaceMap = LookupMap RevNamespace

data RevNamespace

Instances

LookupEntryClass RevNamespace String String

emptyNamespaceMap :: NamespaceMap

data LookupFormula lb gr

Graph formula entry

Constructors

Formula

Fields

formLabel :: lb

formGraph :: gr

Instances

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

Label lb => Show (LookupFormula lb (NSGraph lb))

Label lb => LookupEntryClass (LookupFormula lb (NSGraph lb)) lb (NSGraph lb)

type Formula lb = LookupFormula lb (NSGraph lb)

type FormulaMap lb = LookupMap (LookupFormula lb (NSGraph lb))

emptyFormulaMap :: FormulaMap RDFLabel

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

Add an arc to the graph. It does not check for duplicates nor does it relabel any blank nodes in the input arc.

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 -> [lb]

Return list of all labels (including properties) in the graph satisfying a supplied filter predicate.

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

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

Replace the formulae in the graph.

getFormulae :: NSGraph lb -> FormulaMap lb

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

Add (or replace) a formula.

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

Re-export from GraphClass

class (Eq (lg lb), Eq lb) => LDGraph lg lb where

Labelled Directed Graph class

Minimum required implementation: setArcs, getArcs and containedIn.

NOTE: I wanted to declare this as a subclass of Functor, but the constraint on the label type seems to prevent that. So I've just declared specific instances to be Functors.

Methods

setArcs :: [Arc lb] -> lg lb -> lg lb

Replace the existing arcs in the graph.

getArcs :: lg lb -> [Arc lb]

Extract all the arcs from a graph

extract :: Selector lb -> lg lb -> lg lb

Extract those arcs that match the given Selector.

add :: lg lb -> lg lb -> lg lb

Add the two graphs

delete

Arguments

:: lg lb

g1

-> lg lb

g2

-> lg lb

g2 - g1 -> g3

Remove those arcs in the first graph from the second graph

labels :: lg lb -> [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 :: lg lb -> [lb]

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

containedIn :: lg lb -> lg lb -> Bool

Test for graph containment in another.

update :: ([Arc lb] -> [Arc 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 (Eq lb, Show lb, Ord 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

Constructors

Arc

Fields

asubj :: lb

apred :: lb

aobj :: lb

Instances

Functor Arc

Foldable Arc

Traversable Arc

Eq lb => Eq (Arc lb)

Ord lb => Ord (Arc lb)

Show lb => Show (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.

arcSubj :: Arc lb -> lb

arcPred :: Arc lb -> lb

arcObj :: Arc lb -> lb

type Selector lb = Arc lb -> Bool

Export selected RDFLabel values

res_rdf_type :: RDFLabel

res_rdf_first :: RDFLabel

res_rdf_rest :: RDFLabel

res_rdf_nil :: RDFLabel

res_rdfs_member :: RDFLabel

res_rdfd_GeneralRestriction :: RDFLabel

res_rdfd_onProperties :: RDFLabel

res_rdfd_constraint :: RDFLabel

res_rdfd_maxCardinality :: RDFLabel

res_owl_sameAs :: RDFLabel

res_log_implies :: RDFLabel

Exported for testing

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

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

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.