Term memoization

src/blank-node.js

@@ -1,8 +1,19 @@
 'use strict'
 const ClassOrder = require('./class-order')
-const Node = require('./node')
+const Term = require('./term')
+
+class BlankNode extends Term {
+  /** @private */
+  static normalizeID (id) {
+    if (typeof id === 'string' && id.includes('#')) {
+      // Is a URI with hash fragment
+      let fragments = id.split('#')
+      return fragments[fragments.length - 1]
+    }
+
+    return id
+  }
 
-class BlankNode extends Node {
   constructor (id) {
     super()
     this.termType = BlankNode.termType
@@ -12,13 +23,13 @@ class BlankNode extends Node {
         console.log('Bad blank id:', id)
         throw new Error('Bad id argument to new blank node: ' + id)
       }
-      if (id.includes('#')) {
-        // Is a URI with hash fragment
-        let fragments = id.split('#')
-        id = fragments[fragments.length - 1]
+
+      this.id = BlankNode.normalizeID(id)
+
+      const existing = Term.bnMap[this.id]
+      if (existing) {
+        return existing
       }
-      this.id = id
-      // this.id = '' + BlankNode.nextId++
     } else {
       this.id = 'n' + BlankNode.nextId++
     }
@@ -52,7 +63,7 @@ class BlankNode extends Node {
     return '_:' + this.value
   }
 
-  toString () {
+  generateString () {
     return BlankNode.NTAnonymousNodePrefix + this.id
   }
 }

src/data-factory.js

@@ -1,16 +1,14 @@
 'use strict'
-const BlankNode = require('./blank-node')
 const Collection = require('./collection')
 const DefaultGraph = require('./default-graph')
 const Fetcher = require('./fetcher')
 const IndexedFormula = require('./store')
-const Literal = require('./literal')
-const NamedNode = require('./named-node')
 const Statement = require('./statement')
+const Term = require('./term')
 const Variable = require('./variable')
 
 function blankNode (value) {
-  return new BlankNode(value)
+  return Term.blankNodeByID(value)
 }
 function collection (elements) {
   return new Collection(elements)
@@ -25,21 +23,21 @@ function graph () {
   return new IndexedFormula()
 }
 function lit (val, lang, dt) {
-  return new Literal('' + val, lang, dt)
+  return Term.literalByValue('' + val, lang, dt)
 }
 function literal (value, languageOrDatatype) {
   if (typeof languageOrDatatype === 'string') {
     if (languageOrDatatype.indexOf(':') === -1) {
-      return new Literal(value, languageOrDatatype)
+      return Term.literalByValue(value, languageOrDatatype)
     } else {
-      return new Literal(value, null, namedNode(languageOrDatatype))
+      return Term.literalByValue(value, null, namedNode(languageOrDatatype))
     }
   } else {
-    return new Literal(value, null, languageOrDatatype)
+    return Term.literalByValue(value, null, languageOrDatatype)
   }
 }
 function namedNode (value) {
-  return new NamedNode(value)
+  return Term.namedNodeByIRI(value)
 }
 function quad (subject, predicate, object, graph) {
   graph = graph || new DefaultGraph()

src/fetcher.js

@@ -33,6 +33,7 @@ const Namespace = require('./namespace')
 const rdfParse = require('./parse')
 const parseRDFaDOM = require('./rdfaparser').parseRDFaDOM
 const RDFParser = require('./rdfxmlparser')
+const Term = require('./term')
 const Uri = require('./uri')
 const Util = require('./util')
 const serialize = require('./serialize')
@@ -1066,7 +1067,7 @@ class Fetcher {
    */
   putBack (uri, options = {}) {
     uri = uri.uri || uri // Accept object or string
-    let doc = new NamedNode(uri).doc() // strip off #
+    let doc = Term.namedNodeByIRI(uri).doc() // strip off #
     options.contentType = options.contentType || 'text/turtle'
     options.data = serialize(doc, this.store, doc.uri, options.contentType)
     return this.webOperation('PUT', uri, options)

src/formula.js

@@ -1,13 +1,13 @@
 'use strict'
-const BlankNode = require('./blank-node')
+
 const ClassOrder = require('./class-order')
 const Collection = require('./collection')
-const Literal = require('./literal')
 const log = require('./log')
 const NamedNode = require('./named-node')
 const Node = require('./node')
 const Serializer = require('./serialize')
 const Statement = require('./statement')
+const Term = require('./term')
 const Variable = require('./variable')
 
 /** @module formula */
@@ -44,7 +44,7 @@ class Formula extends Node {
     return this.statements.push(st)
   }
   bnode (id) {
-    return new BlankNode(id)
+    return Term.blankNodeByID(id)
   }
 
   addAll (statements) {
@@ -365,9 +365,9 @@ class Formula extends Node {
   }
   /** Trace statements which connect directly, or through bnodes
    *
-   * @param {NamedNode} subject - The node to start looking for statments
+   * @param {NamedNode} subject - The node to start looking for statements
    * @param {NamedNode} doc - The document to be searched, or null to search all documents
-   * @returns an array of statements, duplicate statements are suppresssed.
+   * @returns an array of statements, duplicate statements are suppressed.
    */
   connectedStatements (subject, doc, excludePredicateURIs) {
     excludePredicateURIs = excludePredicateURIs || []
@@ -413,7 +413,7 @@ class Formula extends Node {
    * Transforms an NTriples string format into a Node.
    * The bnode bit should not be used on program-external values; designed
    * for internal work such as storing a bnode id in an HTML attribute.
-   * This will only parse the strings generated by the vaious toNT() methods.
+   * This will only parse the strings generated by the various toNT() methods.
    */
   fromNT (str) {
     var dt, k, lang
@@ -439,7 +439,7 @@ class Formula extends Node {
         str = str.replace(/\\\\/g, '\\')
         return this.literal(str, lang, dt)
       case '_':
-        return new BlankNode(str.slice(2))
+        return Term.blankNodeByID(str.slice(2))
       case '?':
         return new Variable(str.slice(1))
     }
@@ -480,7 +480,7 @@ class Formula extends Node {
     return collection
   }
   literal (val, lang, dt) {
-    return new Literal('' + val, lang, dt)
+    return Term.literalByValue('' + val, lang, dt)
   }
   /**
    * transform a collection of NTriple URIs into their URI strings
@@ -541,7 +541,7 @@ class Formula extends Node {
     if (name) {
       throw new Error('This feature (kb.sym with 2 args) is removed. Do not assume prefix mappings.')
     }
-    return new NamedNode(uri)
+    return Term.namedNodeByIRI(uri)
   }
   the (s, p, o, g) {
     var x = this.any(s, p, o, g)

src/index.js

@@ -13,6 +13,7 @@ var $rdf = {
   N3Parser: require('./n3parser'),
   NamedNode: require('./named-node'),
   Namespace: require('./namespace'),
+  ns: require('./ns'),
   Node: require('./node'),
   parse: require('./parse'),
   Query: require('./query').Query,
@@ -25,6 +26,7 @@ var $rdf = {
   sparqlUpdateParser: require('./patch-parser'),
   Statement: require('./statement'),
   term: require('./node').fromValue,
+  Term: require('./term'),
   UpdateManager: require('./update-manager'),
   UpdatesSocket: require('./updates-via').UpdatesSocket,
   UpdatesVia: require('./updates-via').UpdatesVia,

src/literal.js

@@ -1,10 +1,10 @@
 'use strict'
 const ClassOrder = require('./class-order')
 const NamedNode = require('./named-node')
-const Node = require('./node')
+const Term = require('./term')
 const XSD = require('./xsd')
 
-class Literal extends Node {
+class Literal extends Term {
   constructor (value, language, datatype) {
     super()
     this.termType = Literal.termType
@@ -14,22 +14,15 @@ class Literal extends Node {
       datatype = XSD.langString
     }
     // If not specified, a literal has the implied XSD.string default datatype
-    if (datatype) {
-      this.datatype = NamedNode.fromValue(datatype)
+    this.datatype = datatype ? NamedNode.fromValue(datatype) : XSD.string
+
+    const existing = Term.findLiteralByValue(value, language, datatype)
+    if (existing) {
+      return existing
     }
   }
   copy () {
-    return new Literal(this.value, this.lang, this.datatype)
-  }
-  equals (other) {
-    if (!other) {
-      return false
-    }
-    return (this.termType === other.termType) &&
-      (this.value === other.value) &&
-      (this.language === other.language) &&
-      ((!this.datatype && !other.datatype) ||
-        (this.datatype && this.datatype.equals(other.datatype)))
+    return Term.literalByValue(this.value, this.lang, this.datatype)
   }
   get language () {
     return this.lang
@@ -52,15 +45,12 @@ class Literal extends Node {
 
     if (this.language) {
       str += '@' + this.language
-    } else if (!this.datatype.equals(XSD.string)) {
+    } else if (this.datatype !== XSD.string) {
       // Only add datatype if it's not a string
       str += '^^' + this.datatype.toCanonical()
     }
     return str
   }
-  toString () {
-    return '' + this.value
-  }
   /**
    * @method fromBoolean
    * @static
@@ -69,7 +59,7 @@ class Literal extends Node {
    */
   static fromBoolean (value) {
     let strValue = value ? '1' : '0'
-    return new Literal(strValue, null, XSD.boolean)
+    return Term.literalByValue(strValue, null, XSD.boolean)
   }
   /**
    * @method fromDate
@@ -87,7 +77,7 @@ class Literal extends Node {
     let date = '' + value.getUTCFullYear() + '-' + d2(value.getUTCMonth() + 1) +
       '-' + d2(value.getUTCDate()) + 'T' + d2(value.getUTCHours()) + ':' +
       d2(value.getUTCMinutes()) + ':' + d2(value.getUTCSeconds()) + 'Z'
-    return new Literal(date, null, XSD.dateTime)
+    return Term.literalByValue(date, null, XSD.dateTime)
   }
   /**
    * @method fromNumber
@@ -106,7 +96,7 @@ class Literal extends Node {
     } else {
       datatype = XSD.double
     }
-    return new Literal(strValue, null, datatype)
+    return Term.literalByValue(strValue, null, datatype)
   }
   /**
    * @method fromValue
@@ -130,7 +120,7 @@ class Literal extends Node {
       case 'number':
         return Literal.fromNumber(value)
       case 'string':
-        return new Literal(value)
+        return Term.literalByValue(value, null, XSD.string)
     }
     throw new Error("Can't make literal from " + value + ' of type ' +
       typeof value)

src/named-node.js

@@ -1,12 +1,12 @@
 'use strict'
 const ClassOrder = require('./class-order')
-const Node = require('./node')
+const Term = require('./term')
 
 /**
  * @class NamedNode
- * @extends Node
+ * @extends Term
  */
-class NamedNode extends Node {
+class NamedNode extends Term {
   /**
    * @constructor
    * @param iri {String}
@@ -32,6 +32,11 @@ class NamedNode extends Node {
       throw new Error(message)
     }
 
+    const existing = Term.nsMap[iri]
+    if (existing) {
+      return existing
+    }
+
     this.value = iri
   }
   /**
@@ -42,7 +47,7 @@ class NamedNode extends Node {
      var p = str.slice(0, -1).lastIndexOf('/')
      var q = str.indexOf('//')
      if ((q >= 0 && p < q + 2) || p < 0) return null
-     return new NamedNode(str.slice(0, p + 1))
+     return Term.namedNodeByIRI(str.slice(0, p + 1))
    }
    /**
     * Returns an NN for the whole web site, ending in slash.
@@ -54,17 +59,18 @@ class NamedNode extends Node {
      if (p < 0) throw new Error('This URI does not have a web site part (origin)')
      var q = str.indexOf('/', p+2)
      if (q < 0) throw new Error('This URI does not have a web site part. (origin)')
-     return new NamedNode(str.slice(0, q + 1))
+     return Term.namedNodeByIRI(str.slice(0, q + 1))
    }
   doc () {
     if (this.uri.indexOf('#') < 0) {
       return this
     } else {
-      return new NamedNode(this.uri.split('#')[0])
+      return Term.namedNodeByIRI(this.uri.split('#')[0])
     }
   }
-  toString () {
-    return '<' + this.uri + '>'
+
+  generateString () {
+     return '<' + this.uri + '>'
   }
 
   /**
@@ -77,14 +83,7 @@ class NamedNode extends Node {
     this.value = uri
   }
   static fromValue (value) {
-    if (typeof value === 'undefined' || value === null) {
-      return value
-    }
-    const isNode = value && value.termType
-    if (isNode) {
-      return value
-    }
-    return new NamedNode(value)
+    return Term.namedNodeByIRI(value)
   }
 }
 NamedNode.termType = 'NamedNode'

src/namespace.js

@@ -1,8 +1,12 @@
-const NamedNode = require('./named-node')
+const Term = require('./term');
 
 function Namespace (nsuri) {
+  Term.namedNodeByIRI(nsuri)
+
   return function (ln) {
-    return new NamedNode(nsuri + (ln || ''))
+    const fullIRI = nsuri + (ln || '')
+
+    return Term.namedNodeByIRI(fullIRI, ln)
   }
 }