Added hashlib::idict<>

3 files changed, 73 insertions, 2 deletions

diff --git a/CodingReadme b/CodingReadme
index 92d54d283..78bc5a3ce 100644
--- a/CodingReadme
+++ b/CodingReadme
@@ -72,6 +72,20 @@ replacement for std::unordered_set<T>. The main characteristics are:
 	- dict<K, T> and pool<T> will have the same order of iteration across
 	  all compilers, standard libraries and architectures.
 
+In addition to dict<K, T> and pool<T> there is also an idict<K> that
+creates a bijective map from K to the integers. For example:
+
+	idict<string, 42> si;
+	log("%d\n", si("hello"));      // will print 42
+	log("%d\n", si("world"));      // will print 43
+	log("%d\n", si.at("world"));   // will print 43
+	log("%d\n", si.at("dummy"));   // will throw exception
+	log("%s\n", si[42].c_str()));  // will print hello
+	log("%s\n", si[43].c_str()));  // will print world
+	log("%s\n", si[44].c_str()));  // will throw exception
+
+It is not possible to remove elements from an idict.
+
   2. Standard STL data types
 
 In Yosys we use std::vector<T> and std::string whenever applicable. When
diff --git a/kernel/hashlib.h b/kernel/hashlib.h
index 72e9bc2ef..52b38a064 100644
--- a/kernel/hashlib.h
+++ b/kernel/hashlib.h
@@ -163,7 +163,11 @@ inline int hashtable_size(int min_size)
 	throw std::length_error("hash table exceeded maximum size.");
 }
 
-template<typename K, typename T, typename OPS = hash_ops<K>>
+template<typename K, typename T, typename OPS = hash_ops<K>> class dict;
+template<typename K, int offset = 0, typename OPS = hash_ops<K>> class idict;
+template<typename K, typename OPS = hash_ops<K>> class pool;
+
+template<typename K, typename T, typename OPS>
 class dict
 {
 	struct entry_t
@@ -485,9 +489,12 @@ public:
 	const_iterator end() const { return const_iterator(nullptr, -1); }
 };
 
-template<typename K, typename OPS = hash_ops<K>>
+template<typename K, typename OPS>
 class pool
 {
+	template<typename, int, typename> friend class idict;
+
+protected:
 	struct entry_t
 	{
 		K udata;
@@ -783,6 +790,55 @@ public:
 	const_iterator end() const { return const_iterator(nullptr, -1); }
 };
 
+template<typename K, int offset, typename OPS>
+class idict
+{
+	pool<K, OPS> database;
+
+public:
+	typedef typename pool<K, OPS>::const_iterator const_iterator;
+
+	int operator()(const K &key)
+	{
+		int hash = database.do_hash(key);
+		int i = database.do_lookup(key, hash);
+		if (i < 0)
+			i = database.do_insert(key, hash);
+		return i + offset;
+	}
+
+	int at(const K &key) const
+	{
+		int hash = database.do_hash(key);
+		int i = database.do_lookup(key, hash);
+		if (i < 0)
+			throw std::out_of_range("idict::at()");
+		return i + offset;
+	}
+
+	int count(const K &key) const
+	{
+		int hash = database.do_hash(key);
+		int i = database.do_lookup(key, hash);
+		return i < 0 ? 0 : 1;
+	}
+
+	void expect(const K &key, int i)
+	{
+		int j = (*this)(key);
+		if (i != j)
+			throw std::out_of_range("idict::expect()");
+	}
+
+	const K &operator[](int index) const
+	{
+		return database.entries.at(index - offset).udata;
+	}
+
+	const_iterator begin() const { return database.begin(); }
+	const_iterator end() const { return database.end(); }
+};
+
 } /* namespace hashlib */
 
 #endif
diff --git a/kernel/yosys.h b/kernel/yosys.h
index d1e01b19c..a6f4cb665 100644
--- a/kernel/yosys.h
+++ b/kernel/yosys.h
@@ -148,6 +148,7 @@ using hashlib::hash_cstr_ops;
 using hashlib::hash_ptr_ops;
 using hashlib::hash_obj_ops;
 using hashlib::dict;
+using hashlib::idict;
 using hashlib::pool;
 
 namespace RTLIL {