lib/sparql/ExprUtils.js
var ExprVar = require('./expr/ExprVar');
var NodeValue = require('./expr/NodeValue');
var NodeValueUtils = require('./NodeValueUtils');
var E_Equals = require('./expr/E_Equals');
var E_LogicalAnd = require('./expr/E_LogicalAnd');
var E_LogicalOr = require('./expr/E_LogicalOr');
var ExprUtils = {
copySubstitute: function(expr, binding) {
var fn = function(node) {
var result = null;
if (node.isVar()) {
// var varName = node.getName();
// var subst = binding.get(varName);
var subst = binding.get(node);
if (subst != null) {
result = subst;
}
}
if (result == null) {
result = node;
}
return result;
};
var result = expr.copySubstitute(fn);
return result;
},
/**
*
* If varNames is omitted, all vars of the binding are used
*/
bindingToExprs: function(binding, vars) {
if (vars == null) {
vars = binding.getVars();
}
var result = [];
vars.forEach(function(v) {
var exprVar = new ExprVar(v);
var node = binding.get(v);
// TODO What if node is NULL
var nodeValue = NodeValueUtils.makeNode(node);
var expr = new E_Equals(exprVar, nodeValue);
result.push(expr);
});
return result;
},
opify: function(exprs, fnCtor) {
var open = exprs;
var next = [];
while (open.length > 1) {
for (var i = 0; i < open.length; i += 2) {
var a = open[i];
if (i + 1 === open.length) {
next.push(a);
break;
}
var b = open[i + 1];
var newExpr = fnCtor(a, b);
next.push(newExpr); // ;new ns.E_LogicalOr(a, b));
}
open = next;
next = [];
}
return open[0];
},
andify: function(exprs) {
var result = this.opify(exprs, function(a, b) {
return new E_LogicalAnd(a, b);
});
return result;
},
orify: function(exprs) {
var result = this.opify(exprs, function(a, b) {
return new E_LogicalOr(a, b);
});
return result;
},
};
module.exports = ExprUtils;