function writeGraph(root, headerful) {
if (headerful) {
writeMagic();
}
var refInfo = findBackRefsAndHoles(root, holeFilter);
backRefSet = refInfo.backRefs;
holeMap = refInfo.holes;
if (backRefSet.size() !== 0) {
backRefMap = oid.createMap();
}
iterate.iterate(root, visitor);
if (headerful) {
writeFooter();
}
}
/**
* Determine the sets of all back-referenced objects and all non-data
* "holes" under the given root. The holes are filtered using the
* given filter, resulting in a map with bindings from the original
* to the filtered objects.
*/
function findBackRefsAndHoles(root, holeFilter) {
var allowHoles = typ.isDefined(holeFilter);
var allRefs = oid.createMap();
var holes = allowHoles ? oid.createMap() : undefined;
function nop() {
// This space intentionally left blank.
}
function keepGoing(obj, name, value, innerVisitor) {
if (innerVisitor) {
innerVisitor();
}
}
function addRef(obj, innerVisitor, mustBeHole) {
if (mustBeHole && !allowHoles) {
throw new Error("Hole-ful graph, but no hole filter.");
}
var count = allRefs.get(obj, 0) + 1;
allRefs.set(obj, count);
if (count === 1) {
if (mustBeHole) {
var already = holes.get(obj);
if (!already) {
var replacement = fixReplacement(obj, holeFilter(obj));
holes.set(obj, replacement);
iterate.iterate(replacement.obj, visitor);
}
} else if (innerVisitor) {
innerVisitor();
}
}
}
function visitFunction(func, innerVisitor) {
addRef(func, innerVisitor, true);
}
function visitObject(obj, innerVisitor) {
if (Buffer.isBuffer(obj)) {
// Suppress the inner visit for buffers, because it is too
// odious to imagine having to cons up all the keys for
// the buffer indices. (Too bad there's no
// `Object.getOwnNamedProperties()` or somesuch.)
addRef(obj, undefined);
} else {
addRef(obj, innerVisitor, !typ.isMap(obj));
}
}
var visitor = {
visitObject: visitObject,
visitArray: addRef,
visitFunction: visitFunction,
visitString: addRef,
visitObjectPrototype: keepGoing,
visitObjectBinding: keepGoing,
visitObjectGetter: keepGoing,
visitObjectSetter: keepGoing,
visitArrayElement: keepGoing,
visitNumber: nop,
visitBoolean: nop,
visitUndefined: nop,
visitNull: nop
};
iterate.iterate(root, visitor);
var backRefs = oid.createSet();
allRefs.forEach(function (ref, count) {
if (count > 1) {
backRefs.add(ref);
}
});
return { backRefs: backRefs, holes: holes };
}