From c6b502d45d2bf916f747411df37df186c4ed4981 Mon Sep 17 00:00:00 2001
From: Benjamin Paassen <bpaassen@techfak.uni-bielefeld.de>
Date: Tue, 13 Jan 2015 23:32:48 +0100
Subject: First version of 'pathTo' function enabling users to request a
 Structure Path from some descriptor to another.

---
 src/core/model/Domain.cpp | 74 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)

(limited to 'src/core/model/Domain.cpp')

diff --git a/src/core/model/Domain.cpp b/src/core/model/Domain.cpp
index 17b1d2d..1fb057e 100644
--- a/src/core/model/Domain.cpp
+++ b/src/core/model/Domain.cpp
@@ -17,6 +17,7 @@
 */
 
 #include <core/common/Rtti.hpp>
+#include <core/common/Exceptions.hpp>
 
 #include "Domain.hpp"
 
@@ -38,6 +39,79 @@ void Descriptor::continueResolve(ResolutionState &state)
 	                         state);
 }
 
+std::vector<Rooted<Node>> Descriptor::pathTo(
+    Handle<StructuredClass> target) const
+{
+	std::vector<Rooted<Node>> path;
+	continuePath(target, path);
+	return path;
+}
+
+static bool pathEquals(const Descriptor& a, const Descriptor& b)
+{
+	// We assume that two Descriptors are equal if their names and domain names
+	// are equal.
+	if (a.getName() != b.getName()) {
+		return false;
+	}
+	Handle<Domain> aDom = a.getParent().cast<Domain>();
+	Handle<Domain> bDom = b.getParent().cast<Domain>();
+	return aDom->getName() == bDom->getName();
+}
+
+//TODO: isa-handling.
+bool Descriptor::continuePath(Handle<StructuredClass> target,
+                              std::vector<Rooted<Node>> &path) const
+{
+	// look if our current node is reachable using the parent references
+	for (auto &pfd : target->getParents()) {
+		Handle<Descriptor> p = pfd->getParent().cast<Descriptor>();
+		if (pathEquals(*this, *p)) {
+			// if we have made the connection, stop the search.
+			path.push_back(pfd);
+			return true;
+		}
+		// look for transparent intermediate nodes.
+		if (!p->isa(RttiTypes::StructuredClass)) {
+			continue;
+		}
+		Handle<StructuredClass> pc = p.cast<StructuredClass>();
+		if (pc->transparent) {
+			// recursion
+			std::vector<Rooted<Node>> cPath = path;
+			if (continuePath(pc, cPath)) {
+				path = std::move(cPath);
+				path.push_back(pc);
+				path.push_back(pfd);
+				return true;
+			}
+		}
+	}
+	// use recursive depth-first search from the top to reach the given child
+	for (auto &fd : fieldDescriptors) {
+		for (auto &c : fd->getChildren()) {
+			if (pathEquals(*c, *target)) {
+				// if we have made the connection, stop the search.
+				path.push_back(fd);
+				return true;
+			}
+			// look for transparent intermediate nodes.
+			if (c->transparent) {
+				// copy the path.
+				std::vector<Rooted<Node>> cPath = path;
+				cPath.push_back(fd);
+				cPath.push_back(c);
+				// recursion.
+				if (c->continuePath(target, cPath)) {
+					path = std::move(cPath);
+					return true;
+				}
+			}
+		}
+	}
+	return false;
+}
+
 /* Class Domain */
 
 void Domain::continueResolve(ResolutionState &state)
-- 
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