Negated Property Set

.changeset/curvy-ways-compare.md

@@ -0,0 +1,6 @@
+---
+"clownface-shacl-path": minor
+---
+
+Adds `NegatedPropertySet` class to support negated paths in `findNodes`, `toAlgebra` and `toAlgebra`
+NOTE: negated paths are not supported in SHACL representation (see https://github.com/w3c/shacl/issues/20)

.changeset/pretty-goats-grow.md

@@ -0,0 +1,5 @@
+---
+"clownface-shacl-path": minor
+---
+
+Allow calling `toSparql` with a path object

package.json

@@ -21,6 +21,7 @@
     "release": "changeset publish"
   },
   "dependencies": {
+    "@rdfjs/term-map": "^2.0.0",
     "@rdfjs/term-set": "^2.0.1",
     "@tpluscode/rdf-ns-builders": ">=3.0.2",
     "@tpluscode/rdf-string": "^1.3.1"

src/index.ts

@@ -11,5 +11,6 @@ export {
   InversePath,
   SequencePath,
   ZeroOrOnePath,
+  NegatedPropertySet,
   fromNode,
 } from './lib/path.js'

src/lib/findNodes.ts

@@ -1,8 +1,9 @@
-import type { NamedNode, Term } from '@rdfjs/types'
+/* eslint-disable camelcase */
+import type { NamedNode, Term, Quad_Predicate, Quad } from '@rdfjs/types'
 import type { MultiPointer } from 'clownface'
 import TermSet from '@rdfjs/term-set'
+import TermMap from '@rdfjs/term-map'
 import * as Path from './path.js'
-import { ShaclPropertyPath } from './path.js'
 
 interface Context {
   pointer: MultiPointer
@@ -67,6 +68,41 @@ class FindNodesVisitor extends Path.PathVisitor<Term[], Context> {
   visitPredicatePath({ term }: Path.PredicatePath, { pointer }: Context): Term[] {
     return pointer.out(term).terms
   }
+
+  visitNegatedPropertySet({ paths }: Path.NegatedPropertySet, { pointer }: Context): Term[] {
+    const outLinks = [...pointer.dataset.match(pointer.term)]
+      .reduce(toPredicateMap('object'), new TermMap())
+
+    const inLinks = [...pointer.dataset.match(null, null, pointer.term)]
+      .reduce(toPredicateMap('subject'), new TermMap())
+    let includeInverse = false
+
+    for (const path of paths) {
+      if (path instanceof Path.PredicatePath) {
+        outLinks.delete(path.term)
+      } else {
+        includeInverse = true
+        inLinks.delete(path.path.term)
+      }
+    }
+
+    if (includeInverse) {
+      return [...new TermSet([...outLinks.values(), ...inLinks.values()].flatMap(v => [...v]))]
+    }
+
+    return [...outLinks.values()].flatMap(v => [...v])
+  }
+}
+
+function toPredicateMap(so: 'subject' | 'object') {
+  return (map: TermMap<Quad_Predicate, TermSet>, quad: Quad) => {
+    if (!map.has(quad.predicate)) {
+      map.set(quad.predicate, new TermSet())
+    }
+
+    map.get(quad.predicate)!.add(quad[so])
+    return map
+  }
 }
 
 /**
@@ -75,11 +111,9 @@ class FindNodesVisitor extends Path.PathVisitor<Term[], Context> {
  * @param pointer starting node
  * @param shPath SHACL Property Path
  */
-export function findNodes(pointer: MultiPointer, shPath: MultiPointer | NamedNode | ShaclPropertyPath): MultiPointer {
-  let path: ShaclPropertyPath
-  if ('termType' in shPath) {
-    path = Path.fromNode(pointer.node(shPath))
-  } else if ('value' in shPath) {
+export function findNodes(pointer: MultiPointer, shPath: MultiPointer | NamedNode | Path.ShaclPropertyPath): MultiPointer {
+  let path: Path.ShaclPropertyPath
+  if ('termType' in shPath || 'value' in shPath) {
     path = Path.fromNode(shPath)
   } else {
     path = shPath

src/lib/path.ts

@@ -25,6 +25,9 @@ export abstract class PathVisitor<R = void, TArg = unknown> {
     if (path instanceof ZeroOrOnePath) {
       return this.visitZeroOrOnePath(path, arg)
     }
+    if (path instanceof NegatedPropertySet) {
+      return this.visitNegatedPropertySet(path, arg)
+    }
 
     throw new Error('Unexpected path')
   }
@@ -36,6 +39,7 @@ export abstract class PathVisitor<R = void, TArg = unknown> {
   abstract visitZeroOrMorePath(path: ZeroOrMorePath, arg?: TArg): R
   abstract visitOneOrMorePath(path: OneOrMorePath, arg?: TArg): R
   abstract visitZeroOrOnePath(path: ZeroOrOnePath, arg?: TArg): R
+  abstract visitNegatedPropertySet(path: NegatedPropertySet, arg?: TArg): R
 }
 
 export abstract class ShaclPropertyPath {
@@ -72,8 +76,8 @@ export class AlternativePath extends ShaclPropertyPath {
   }
 }
 
-export class InversePath extends ShaclPropertyPath {
-  constructor(public path: ShaclPropertyPath) {
+export class InversePath<P extends ShaclPropertyPath = ShaclPropertyPath> extends ShaclPropertyPath {
+  constructor(public path: P) {
     super()
   }
 
@@ -112,6 +116,16 @@ export class ZeroOrOnePath extends ShaclPropertyPath {
   }
 }
 
+export class NegatedPropertySet extends ShaclPropertyPath {
+  constructor(public paths: Array<PredicatePath | InversePath<PredicatePath>>) {
+    super()
+  }
+
+  accept<T>(visitor: PathVisitor<any, T>, arg: T) {
+    return visitor.visitNegatedPropertySet(this, arg)
+  }
+}
+
 interface Options {
   allowNamedNodeSequencePaths?: boolean
 }

src/lib/toAlgebra.ts

@@ -55,14 +55,39 @@ class ToAlgebra extends Path.PathVisitor<PropertyPath | NamedNode> {
       items: [path.path.accept(this)],
     }
   }
+
+  visitNegatedPropertySet({ paths }: Path.NegatedPropertySet): PropertyPath {
+    return {
+      type: 'path',
+      pathType: '!',
+      items: paths.map((path) => {
+        if (path instanceof Path.PredicatePath) {
+          return path.term
+        }
+
+        return {
+          type: 'path',
+          pathType: '^',
+          items: [path.path.term],
+        }
+      }),
+    }
+  }
 }
 
 /**
  * Creates a sparqljs object which represents a SHACL path as Property Path
  *
- * @param path SHACL Property Path
+ * @param shPath SHACL Property Path
  */
-export function toAlgebra(path: MultiPointer | NamedNode): PropertyPath | NamedNode {
+export function toAlgebra(shPath: MultiPointer | NamedNode | Path.ShaclPropertyPath): PropertyPath | NamedNode {
+  let path: Path.ShaclPropertyPath
+  if ('termType' in shPath || 'value' in shPath) {
+    path = Path.fromNode(shPath)
+  } else {
+    path = shPath
+  }
+
   const visitor = new ToAlgebra()
-  return visitor.visit(Path.fromNode(path))
+  return visitor.visit(path)
 }

src/lib/toSparql.ts

@@ -1,7 +1,7 @@
 import type { NamedNode } from '@rdfjs/types'
 import { SparqlTemplateResult, sparql } from '@tpluscode/rdf-string'
 import { MultiPointer } from 'clownface'
-import { assertWellFormedPath, fromNode, PathVisitor, ShaclPropertyPath } from './path.js'
+import { assertWellFormedPath, fromNode, NegatedPropertySet, PathVisitor, ShaclPropertyPath } from './path.js'
 import * as Path from './path.js'
 
 class ToSparqlPropertyPath extends PathVisitor<SparqlTemplateResult, { isRoot: boolean }> {
@@ -45,6 +45,10 @@ class ToSparqlPropertyPath extends PathVisitor<SparqlTemplateResult, { isRoot: b
     return sparql`${predicate}`
   }
 
+  visitNegatedPropertySet(path: NegatedPropertySet): SparqlTemplateResult {
+    return sparql`!(${path.paths.reduce(this.pathChain('|'), sparql``)})`
+  }
+
   private pathChain(operator: string) {
     return (previous: SparqlTemplateResult, current: Path.ShaclPropertyPath, index: number) => {
       if (index === 0) {