/// <summary>
/// Removes tokens from this JSON token using a collection of patterns.
/// </summary>
public static void Subset(this JToken root, PatternCollection patterns)
{
var decisions = new DecisionDictionary();
foreach (var pattern in patterns)
{
var matchedTokens = root.SelectTokens(pattern.Expression);
var toExclude = !pattern.IsNegated;
decisions.AddOrUpdateFor(matchedTokens, toExclude);
}
Subset(root, decisions.GetFor(root), decisions);
}
/// <summary>
/// Traverses the JSON in post-order, removing tokens bottom-up.
/// </summary>
private static void Subset(JToken token, Decision decision, DecisionDictionary decisions)
{
foreach (var child in token.Children().ToArray())
{
var inherited = decision;
var decisionForChild = Decision.GetNewer(inherited, decisions.GetFor(child));
Subset(child, decisionForChild, decisions);
}
var isLeafToExclude = token is JValue && decision != null && decision.Remove;
var isChildlessAncestor = !(token is JValue) && !token.HasValues;
if (isLeafToExclude || isChildlessAncestor)
token.RemoveFromParent();
}