From 302fc80f638783d17cd3b496284a535044241297 Mon Sep 17 00:00:00 2001
From: olpc user <olpc@xo-5d-f7-86.localdomain>
Date: Thu, 21 Nov 2019 06:17:34 -0500
Subject: simple c++ refs

---
 starts/meaning-vm/concept.hpp | 74 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 starts/meaning-vm/concept.hpp

(limited to 'starts/meaning-vm/concept.hpp')

diff --git a/starts/meaning-vm/concept.hpp b/starts/meaning-vm/concept.hpp
new file mode 100644
index 0000000..981835f
--- /dev/null
+++ b/starts/meaning-vm/concept.hpp
@@ -0,0 +1,74 @@
+#pragma once
+
+#include <map>
+#include <stdexcept>
+#include <string>
+#include <vector>
+
+using cid = struct concept *;
+
+struct concept
+{
+	// a concept is made of concept-typed links to other concepts
+	std::multimap<cid,cid> links;
+	using array = std::vector<cid>;
+
+	cid id();
+	cid get(cid type); // returns first
+	array getAll(cid type);
+	void link(cid type, cid target);
+	void unlink(cid type, cid target);
+};
+
+template <typename T>
+struct value : public concept, public T
+{
+	static value<T>& of(cid c)
+	{
+		return *static_cast<value<T>*>(c);
+	}
+};
+
+cid concept::id()
+{
+	return this;
+}
+
+cid concept::get(cid type)
+{
+	auto result = links.equal_range(type);
+	if (result.first == result.second) {
+		throw std::out_of_range("no such concept link to get");
+	}
+	return result.first->second;
+}
+
+concept::array concept::getAll(cid type)
+{
+	array ret;
+	for (
+		auto range = links.equal_range(type);
+		range.first != range.second;
+		++ range.first
+	) { 
+		ret.push_back(range.first->second);
+	}
+	return ret;
+}
+
+void concept::link(cid type, cid target)
+{
+	links.insert({type, target});
+}
+
+void concept::unlink(cid type, cid target)
+{
+	auto ls = links.equal_range(type);
+	for (auto l = ls.first; l != ls.second; ++ l) {
+		if (l->second == target) {
+			links.erase(l);
+			return;
+		}
+	}
+	throw std::out_of_range("no such concept link to erase");
+}
-- 
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