Merge pull request #159 from tfoleyNV/name-type

Name type

1 files changed, 81 insertions, 0 deletions

diff --git a/source/slang/name.h b/source/slang/name.h
new file mode 100644
index 000000000..e492c4507
--- /dev/null
+++ b/source/slang/name.h
@@ -0,0 +1,81 @@
+// name.h
+#ifndef SLANG_NAME_H_INCLUDED
+#define SLANG_NAME_H_INCLUDED
+
+// This file defines the `Name` type, used to represent
+// the name of types, variables, etc. in the AST.
+
+#include "../core/basic.h"
+
+namespace Slang {
+
+// The `Name` type is used to represent the name of a type, variable, etc.
+//
+// The key benefit of using `Name`s instead of raw strings is that `Name`s
+// can be compared for equality just by testing pointer equality. Names
+// also don't require any memory management; you can just retain an ordinary
+// pointer to one and not deal with reference-counting overhead.
+//
+// In order to provide these benefits, a `Name` can only be created using
+// a `NamePool` that owns the allocations for all the names (so they get
+// cleaned up when the pool is deleted), and which is responsible for
+// ensuring the uniqueness of name objects.
+//
+class Name : public RefObject
+{
+public:
+    // The raw text of the name.
+    //
+    // Note that at some point in the future we might have other categories
+    // of name than "simple" names, and so this might change to a structured
+    // ADT instead of a simple string.
+    String text;
+};
+
+// Get the textual string representation of a name
+// (e.g., so that it can be printed).
+String getText(Name* name);
+
+// A `RootNamePool` is used to store and look up names.
+// If two systems need to work together with names, and be sure that they
+// get equivalent names for a string like `"Foo"`, then they need to use
+// the same root name pool (directly or indirectly).
+//
+struct RootNamePool
+{
+    // The mapping from text strings to the corresponding name.
+    Dictionary<String, RefPtr<Name> > names;
+};
+
+// A `NamePool` is effectively a way of storing a subset of the
+// names that have been created through a `RootNamePool`.
+//
+// The intention is that eventually we will add the ability to clean
+// up a `NamePool`, and remove the names it created from the corresponding
+// `RootNamePool` *if* those names are no longer in use.
+//
+// The goal of such an approach would be to ensure that the memory
+// usage of a `Session` can't bloat over time just because of multiple
+// `CompileRequest`s being created, used, and then destroyed (each time
+// adding just a few more strings to the name mapping).
+//
+struct NamePool
+{
+    // Find or create the `Name` that represents the given `text`.
+    Name* getName(String const& text);
+
+    // Set the parent name pool to use for lookup
+    void setRootNamePool(RootNamePool* rootNamePool)
+    {
+        this->rootPool = rootNamePool;
+    }
+
+    //
+
+    // The root name pool to use for storage/lookup
+    RootNamePool* rootPool = nullptr;
+};
+
+} // namespace Slang
+
+#endif