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UmbracoXPathPathSyntaxParser.cs
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UmbracoXPathPathSyntaxParser.cs
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using System;
using System.Collections.Generic;
using System.Linq;
namespace Umbraco.Core.Xml
{
/// <summary>
/// This is used to parse our customize Umbraco XPath expressions (i.e. that include special tokens like $site) into
/// a real XPath statement
/// </summary>
internal class UmbracoXPathPathSyntaxParser
{
/// <summary>
/// Parses custom umbraco xpath expression
/// </summary>
/// <param name="xpathExpression">The Xpath expression</param>
/// <param name="nodeContextId">
/// The current node id context of executing the query - null if there is no current node, in which case
/// some of the parameters like $current, $parent, $site will be disabled
/// </param>
/// <param name="getPath">The callback to create the nodeId path, given a node Id</param>
/// <param name="publishedContentExists">The callback to return whether a published node exists based on Id</param>
/// <returns></returns>
public static string ParseXPathQuery(
string xpathExpression,
int? nodeContextId,
Func<int, IEnumerable<string>> getPath,
Func<int, bool> publishedContentExists)
{
// TODO: This should probably support some of the old syntax and token replacements, currently
// it does not, there is a ticket raised here about it: http://issues.umbraco.org/issue/U4-6364
// previous tokens were: "$currentPage", "$ancestorOrSelf", "$parentPage" and I believe they were
// allowed 'inline', not just at the beginning... whether or not we want to support that is up
// for discussion.
if (xpathExpression == null) throw new ArgumentNullException(nameof(xpathExpression));
if (string.IsNullOrWhiteSpace(xpathExpression)) throw new ArgumentException("Value can't be empty or consist only of white-space characters.", nameof(xpathExpression));
if (getPath == null) throw new ArgumentNullException(nameof(getPath));
if (publishedContentExists == null) throw new ArgumentNullException(nameof(publishedContentExists));
//no need to parse it
if (xpathExpression.StartsWith("$") == false)
return xpathExpression;
//get nearest published item
Func<IEnumerable<string>, int> getClosestPublishedAncestor = (path =>
{
foreach (var i in path)
{
int idAsInt;
if (int.TryParse(i, out idAsInt))
{
var exists = publishedContentExists(int.Parse(i));
if (exists)
return idAsInt;
}
}
return -1;
});
const string rootXpath = "id({0})";
//parseable items:
var vars = new Dictionary<string, Func<string, string>>();
//These parameters must have a node id context
if (nodeContextId.HasValue)
{
vars.Add("$current", q =>
{
var closestPublishedAncestorId = getClosestPublishedAncestor(getPath(nodeContextId.Value));
return q.Replace("$current", string.Format(rootXpath, closestPublishedAncestorId));
});
vars.Add("$parent", q =>
{
//remove the first item in the array if its the current node
//this happens when current is published, but we are looking for its parent specifically
var path = getPath(nodeContextId.Value).ToArray();
if (path[0] == nodeContextId.ToString())
{
path = path.Skip(1).ToArray();
}
var closestPublishedAncestorId = getClosestPublishedAncestor(path);
return q.Replace("$parent", string.Format(rootXpath, closestPublishedAncestorId));
});
vars.Add("$site", q =>
{
var closestPublishedAncestorId = getClosestPublishedAncestor(getPath(nodeContextId.Value));
return q.Replace("$site", string.Format(rootXpath, closestPublishedAncestorId) + "/ancestor-or-self::*[@level = 1]");
});
}
// TODO: This used to just replace $root with string.Empty BUT, that would never work
// the root is always "/root . Need to confirm with Per why this was string.Empty before!
vars.Add("$root", q => q.Replace("$root", "/root"));
foreach (var varible in vars)
{
if (xpathExpression.StartsWith(varible.Key))
{
xpathExpression = varible.Value(xpathExpression);
break;
}
}
return xpathExpression;
}
}
}