link-rdflib/lib/sparql-to-query.js

an RDF library for node.js, patched for speed.

"use strict";

// Converting between SPARQL queries and the $rdf query API

/*

function SQuery () {
  this.terms = []
  return this
}

STerm.prototype.toString = STerm.val
SQuery.prototype.add = function (str) {this.terms.push()}*/
var log = require('./log');

var Query = require('./query').Query; // const Fetcher = require('./fetcher')

/**
 * @SPARQL: SPARQL text that is converted to a query object which is returned.
 * @testMode: testing flag. Prevents loading of sources.
 */


function SPARQLToQuery(SPARQL, testMode, kb) {
  // AJAR_ClearTable()
  var variableHash = [];

  function makeVar(name) {
    if (variableHash[name]) {
      return variableHash[name];
    }

    var newVar = kb.variable(name);
    variableHash[name] = newVar;
    return newVar;
  } // term type functions


  function isRealText(term) {
    return typeof term === 'string' && term.match(/[^ \n\t]/);
  }

  function isVar(term) {
    return typeof term === 'string' && term.match(/^[\?\$]/);
  }

  function fixSymbolBrackets(term) {
    if (typeof term === 'string') {
      return term.replace(/^&lt;/, '<').replace(/&gt;$/, '>');
    } else {
      return term;
    }
  }

  function isSymbol(term) {
    return typeof term === 'string' && term.match(/^<[^>]*>$/);
  }

  function isBnode(term) {
    return typeof term === 'string' && (term.match(/^_:/) || term.match(/^$/));
  }

  function isPrefix(term) {
    return typeof term === 'string' && term.match(/:$/);
  }

  function isPrefixedSymbol(term) {
    return typeof term === 'string' && term.match(/^:|^[^_][^:]*:/);
  }

  function getPrefix(term) {
    var a = term.split(':');
    return a[0];
  }

  function getSuffix(term) {
    var a = term.split(':');
    return a[1];
  }

  function removeBrackets(term) {
    if (isSymbol(term)) {
      return term.slice(1, term.length - 1);
    } else {
      return term;
    }
  } // takes a string and returns an array of strings and Literals in the place of literals


  function parseLiterals(str) {
    // var sin = (str.indexOf(/[ \n]\'/)==-1)?null:str.indexOf(/[ \n]\'/), doub = (str.indexOf(/[ \n]\"/)==-1)?null:str.indexOf(/[ \n]\"/)
    var sin = str.indexOf("'") === -1 ? null : str.indexOf("'");
    var doub = str.indexOf('"') === -1 ? null : str.indexOf('"'); // alert("S: "+sin+" D: "+doub)

    if (!sin && !doub) {
      var a = new Array(1);
      a[0] = str;
      return a;
    }

    var res = new Array(2);
    var br;
    var ind;

    if (!sin || doub && doub < sin) {
      br = '"';
      ind = doub;
    } else if (!doub || sin && sin < doub) {
      br = "'";
      ind = sin;
    } else {
      log.error('SQARQL QUERY OOPS!');
      return res;
    }

    res[0] = str.slice(0, ind);
    var end = str.slice(ind + 1).indexOf(br);

    if (end === -1) {
      log.error('SPARQL parsing error: no matching parentheses in literal ' + str);
      return str;
    } // alert(str.slice(end + ind + 2).match(/^\^\^/))


    var end2;

    if (str.slice(end + ind + 2).match(/^\^\^/)) {
      end2 = str.slice(end + ind + 2).indexOf(' '); // alert(end2)

      res[1] = kb.literal(str.slice(ind + 1, ind + 1 + end), '', kb.sym(removeBrackets(str.slice(ind + 4 + end, ind + 2 + end + end2)))); // alert(res[1].datatype.uri)

      res = res.concat(parseLiterals(str.slice(end + ind + 3 + end2)));
    } else if (str.slice(end + ind + 2).match(/^@/)) {
      end2 = str.slice(end + ind + 2).indexOf(' '); // alert(end2)

      res[1] = kb.literal(str.slice(ind + 1, ind + 1 + end), str.slice(ind + 3 + end, ind + 2 + end + end2), null); // alert(res[1].datatype.uri)

      res = res.concat(parseLiterals(str.slice(end + ind + 2 + end2)));
    } else {
      res[1] = kb.literal(str.slice(ind + 1, ind + 1 + end), '', null);
      log.info('Literal found: ' + res[1]);
      res = res.concat(parseLiterals(str.slice(end + ind + 2))); // finds any other literals
    }

    return res;
  }

  function spaceDelimit(str) {
    str = str.replace(/\(/g, ' ( ').replace(/\)/g, ' ) ').replace(/</g, ' <').replace(/>/g, '> ').replace(/{/g, ' { ').replace(/}/g, ' } ').replace(/[\t\n\r]/g, ' ').replace(/; /g, ' ; ').replace(/\. /g, ' . ').replace(/, /g, ' , ');
    log.info('New str into spaceDelimit: \n' + str);
    var res = [];
    var br = str.split(' ');

    for (var x in br) {
      if (isRealText(br[x])) {
        res = res.concat(br[x]);
      }
    }

    return res;
  }

  function replaceKeywords(input) {
    var strarr = input;

    for (var x = 0; x < strarr.length; x++) {
      if (strarr[x] === 'a') {
        strarr[x] = '<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>';
      }

      if (strarr[x] === 'is' && strarr[x + 2] === 'of') {
        strarr.splice(x, 1);
        strarr.splice(x + 1, 1);
        var s = strarr[x - 1];
        strarr[x - 1] = strarr[x + 1];
        strarr[x + 1] = s;
      }
    }

    return strarr;
  }

  function toTerms(input) {
    var res = [];

    for (var x = 0; x < input.length; x++) {
      if (typeof input[x] !== 'string') {
        res[x] = input[x];
        continue;
      }

      input[x] = fixSymbolBrackets(input[x]);

      if (isVar(input[x])) {
        res[x] = makeVar(input[x].slice(1));
      } else if (isBnode(input[x])) {
        log.info(input[x] + ' was identified as a bnode.');
        res[x] = kb.bnode();
      } else if (isSymbol(input[x])) {
        log.info(input[x] + ' was identified as a symbol.');
        res[x] = kb.sym(removeBrackets(input[x]));
      } else if (isPrefixedSymbol(input[x])) {
        log.info(input[x] + ' was identified as a prefixed symbol');

        if (prefixes[getPrefix(input[x])]) {
          res[x] = kb.sym(input[x] = prefixes[getPrefix(input[x])] + getSuffix(input[x]));
        } else {
          log.error('SPARQL error: ' + input[x] + ' with prefix ' + getPrefix(input[x]) + ' does not have a correct prefix entry.');
          res[x] = input[x];
        }
      } else {
        res[x] = input[x];
      }
    }

    return res;
  }

  function tokenize(str) {
    var token1 = parseLiterals(str);
    var token2 = [];

    for (var x in token1) {
      if (typeof token1[x] === 'string') {
        token2 = token2.concat(spaceDelimit(token1[x]));
      } else {
        token2 = token2.concat(token1[x]);
      }
    }

    token2 = replaceKeywords(token2);
    log.info('SPARQL Tokens: ' + token2);
    return token2;
  } // CASE-INSENSITIVE


  function arrayIndexOf(str, arr) {
    for (var i = 0; i < arr.length; i++) {
      if (typeof arr[i] !== 'string') {
        continue;
      }

      if (arr[i].toLowerCase() === str.toLowerCase()) {
        return i;
      }
    } // log.warn("No instance of "+str+" in array "+arr)


    return null;
  } // CASE-INSENSITIVE


  function arrayIndicesOf(str, arr) {
    var ind = [];

    for (var i = 0; i < arr.length; i++) {
      if (typeof arr[i] !== 'string') {
        continue;
      }

      if (arr[i].toLowerCase() === str.toLowerCase()) {
        ind.push(i);
      }
    }

    return ind;
  }

  function setVars(input, query) {
    log.info('SPARQL vars: ' + input);

    for (var x in input) {
      if (isVar(input[x])) {
        log.info('Added ' + input[x] + ' to query variables from SPARQL');
        var v = makeVar(input[x].slice(1));
        query.vars.push(v);
        v.label = input[x].slice(1);
      } else {
        log.warn('Incorrect SPARQL variable in SELECT: ' + input[x]);
      }
    }
  }

  function getPrefixDeclarations(input) {
    var prefInd = arrayIndicesOf('PREFIX', input);
    var res = [];

    for (var i in prefInd) {
      var a = input[prefInd[i] + 1];
      var b = input[prefInd[i] + 2];

      if (!isPrefix(a)) {
        log.error('Invalid SPARQL prefix: ' + a);
      } else if (!isSymbol(b)) {
        log.error('Invalid SPARQL symbol: ' + b);
      } else {
        log.info('Prefix found: ' + a + ' -> ' + b);
        var pref = getPrefix(a);
        var symbol = removeBrackets(b);
        res[pref] = symbol;
      }
    }

    return res;
  }

  function getMatchingBracket(arr, open, close) {
    log.info('Looking for a close bracket of type ' + close + ' in ' + arr);
    var index = 0;

    for (var i = 0; i < arr.length; i++) {
      if (arr[i] === open) {
        index++;
      }

      if (arr[i] === close) {
        index--;
      }

      if (index < 0) {
        return i;
      }
    }

    log.error('Statement had no close parenthesis in SPARQL query');
    return 0;
  }

  function constraintGreaterThan(value) {
    this.describe = function (varstr) {
      return varstr + ' > ' + value.toNT();
    };

    this.test = function (term) {
      if (term.value.match(/[0-9]+(\.[0-9]+)?([eE][+-]?[0-9]+)?/)) {
        return parseFloat(term.value) > parseFloat(value);
      } else {
        return term.toNT() > value.toNT();
      }
    };

    return this;
  }

  function constraintLessThan(value) {
    // this is not the recommended usage. Should only work on literal, numeric, dateTime
    this.describe = function (varstr) {
      return varstr + ' < ' + value.toNT();
    };

    this.test = function (term) {
      // this.describe = function (varstr) { return varstr + " < "+value }
      if (term.value.match(/[0-9]+(\.[0-9]+)?([eE][+-]?[0-9]+)?/)) {
        return parseFloat(term.value) < parseFloat(value);
      } else {
        return term.toNT() < value.toNT();
      }
    };

    return this;
  } // This should only work on literals but doesn't.


  function ConstraintEqualTo(value) {
    this.describe = function (varstr) {
      return varstr + ' = ' + value.toNT();
    };

    this.test = function (term) {
      return value.sameTerm(term);
    };

    return this;
  } // value must be a literal


  function ConstraintRegexp(value) {
    this.describe = function (varstr) {
      return "REGEXP( '" + value + "' , " + varstr + ' )';
    };

    this.test = function (term) {
      var str = value; // str = str.replace(/^//,"").replace(//$/,"")

      var rg = new RegExp(str);

      if (term.value) {
        return rg.test(term.value);
      } else {
        return false;
      }
    };
  }

  function setConstraint(input, pat) {
    if (input.length === 3 && input[0].termType === 'Variable' && (input[2].termType === 'NamedNode' || input[2].termType === 'Literal')) {
      if (input[1] === '=') {
        log.debug('Constraint added: ' + input);
        pat.constraints[input[0]] = new ConstraintEqualTo(input[2]);
      } else if (input[1] === '>') {
        log.debug('Constraint added: ' + input);
        pat.constraints[input[0]] = new ConstraintEqualTo(input[2]);
      } else if (input[1] === '<') {
        log.debug('Constraint added: ' + input);
        pat.constraints[input[0]] = new ConstraintEqualTo(input[2]);
      } else {
        log.warn("I don't know how to handle the constraint: " + input);
      }
    } else if (input.length === 6 && typeof input[0] === 'string' && input[0].toLowerCase() === 'regexp' && input[1] === '(' && input[5] === ')' && input[3] === ',' && input[4].termType === 'Variable' && input[2].termType === 'Literal') {
      log.debug('Constraint added: ' + input);
      pat.constraints[input[4]] = new ConstraintRegexp(input[2].value);
    } // log.warn("I don't know how to handle the constraint: "+input)
    // alert("length: "+input.length+" input 0 type: "+input[0].termType+" input 1: "+input[1]+" input[2] type: "+input[2].termType)

  }

  function setOptional(terms, pat) {
    log.debug('Optional query: ' + terms + ' not yet implemented.');
    var opt = kb.formula();
    setWhere(terms, opt);
    pat.optional.push(opt);
  }

  function setWhere(input, pat) {
    var terms = toTerms(input);
    var end;
    log.debug('WHERE: ' + terms);
    var opt; // var opt = arrayIndicesOf("OPTIONAL",terms)

    while (arrayIndexOf('OPTIONAL', terms)) {
      opt = arrayIndexOf('OPTIONAL', terms);
      log.debug('OPT: ' + opt + ' ' + terms[opt] + ' in ' + terms);

      if (terms[opt + 1] !== '{') {
        log.warn('Bad optional opening bracket in word ' + opt);
      }

      end = getMatchingBracket(terms.slice(opt + 2), '{', '}');

      if (end === -1) {
        log.error('No matching bracket in word ' + opt);
      } else {
        setOptional(terms.slice(opt + 2, opt + 2 + end), pat); // alert(pat.statements[0].toNT())

        opt = arrayIndexOf('OPTIONAL', terms);
        end = getMatchingBracket(terms.slice(opt + 2), '{', '}');
        terms.splice(opt, end + 3);
      }
    }

    log.debug('WHERE after optionals: ' + terms);

    while (arrayIndexOf('FILTER', terms)) {
      var filt = arrayIndexOf('FILTER', terms);

      if (terms[filt + 1] !== '(') {
        log.warn('Bad filter opening bracket in word ' + filt);
      }

      end = getMatchingBracket(terms.slice(filt + 2), '(', ')');

      if (end === -1) {
        log.error('No matching bracket in word ' + filt);
      } else {
        setConstraint(terms.slice(filt + 2, filt + 2 + end), pat);
        filt = arrayIndexOf('FILTER', terms);
        end = getMatchingBracket(terms.slice(filt + 2), '(', ')');
        terms.splice(filt, end + 3);
      }
    }

    log.debug('WHERE after filters and optionals: ' + terms);
    extractStatements(terms, pat);
  }

  function extractStatements(terms, formula) {
    var arrayZero = new Array(1);
    arrayZero[0] = -1; // this is just to add the beginning of the where to the periods index.

    var per = arrayZero.concat(arrayIndicesOf('.', terms));
    var stat = [];

    for (var x = 0; x < per.length - 1; x++) {
      stat[x] = terms.slice(per[x] + 1, per[x + 1]);
    } // Now it's in an array of statements


    for (x in stat) {
      // THIS MUST BE CHANGED FOR COMMA, SEMICOLON
      log.info('s+p+o ' + x + ' = ' + stat[x]);
      var subj = stat[x][0];
      stat[x].splice(0, 1);
      var sem = arrayZero.concat(arrayIndicesOf(';', stat[x]));
      sem.push(stat[x].length);
      var stat2 = [];

      for (var y = 0; y < sem.length - 1; y++) {
        stat2[y] = stat[x].slice(sem[y] + 1, sem[y + 1]);
      }

      for (x in stat2) {
        log.info('p+o ' + x + ' = ' + stat[x]);
        var pred = stat2[x][0];
        stat2[x].splice(0, 1);
        var com = arrayZero.concat(arrayIndicesOf(',', stat2[x]));
        com.push(stat2[x].length);
        var stat3 = [];

        for (y = 0; y < com.length - 1; y++) {
          stat3[y] = stat2[x].slice(com[y] + 1, com[y + 1]);
        }

        for (x in stat3) {
          var obj = stat3[x][0];
          log.info('Subj=' + subj + ' Pred=' + pred + ' Obj=' + obj);
          formula.add(subj, pred, obj);
        }
      }
    }
  } // ******************************* Body of SPARQLToQuery ***************************//


  log.info('SPARQL input: \n' + SPARQL);
  var q = new Query();
  var sp = tokenize(SPARQL); // first tokenize everything

  var prefixes = getPrefixDeclarations(sp);

  if (!prefixes.rdf) {
    prefixes.rdf = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#';
  }

  if (!prefixes.rdfs) {
    prefixes.rdfs = 'http://www.w3.org/2000/01/rdf-schema#';
  }

  var selectLoc = arrayIndexOf('SELECT', sp);
  var whereLoc = arrayIndexOf('WHERE', sp);

  if (selectLoc < 0 || whereLoc < 0 || selectLoc > whereLoc) {
    log.error('Invalid or nonexistent SELECT and WHERE tags in SPARQL query');
    return false;
  }

  setVars(sp.slice(selectLoc + 1, whereLoc), q);
  setWhere(sp.slice(whereLoc + 2, sp.length - 1), q.pat);

  if (testMode) {
    return q;
  }

  for (var x in q.pat.statements) {
    var st = q.pat.statements[x];

    if (st.subject.termType === 'NamedNode') {
      if (kb.fetcher) {
        kb.fetcher.lookUpThing(st.subject, 'sparql:' + st.subject);
      }
    }

    if (st.object.termType === 'NamedNode') {
      if (kb.fetcher) {
        kb.fetcher.lookUpThing(st.object, 'sparql:' + st.object);
      }
    }
  } // alert(q.pat)


  return q; // checkVars()
  // *******************************************************************//
}

module.exports = SPARQLToQuery;