Make source location lightweight

Fixes #24

So far the code has used a representation for source locations that is heavy-weight, but typical of research or hobby compilers: a `struct` type containing a line number and a (heap-allocated) string.
This is actually very convenient for debugging, but it means that any data structure that might contain a source location needs careful memory management (because of those strings) and has a tendency to bloat.

The new represnetation is that a source location is just a pointer-sized integer.
In the simplest mental model, you can think of this as just counting every byte of source text that is passed in, and using those to name locations.

Finding the path and line number that corresponds to a location involves a lookup step, but we can arrange to store all the files in an array sorted by their start locations, and do a binary search.
Finding line numbers inside a file is similarly fast (one you pay a one-time cost to build an array of starting offsets for lines).

More advanced compilers like clang actually go further and create a unique range of source locations to represent a file each time it gets included, so that they can track the include stack and reproduce it in diagnostic messages.
I'm not doing anything that clever here.

1 files changed, 27 insertions, 18 deletions

diff --git a/source/slang/compiler.h b/source/slang/compiler.h
index fd40a62f6..5a6cb5c19 100644
--- a/source/slang/compiler.h
+++ b/source/slang/compiler.h
@@ -122,17 +122,7 @@ namespace Slang
 //			GLSL,	// pass through GLSL to `glslang` library
     };
 
-    // Represents a single source file (either an on-disk file, or a
-    // "virtual" file passed in as a string)
-    class SourceFile : public RefObject
-    {
-    public:
-        // The file path for a real file, or the nominal path for a virtual file
-        String path;
-
-        // The actual contents of the file
-        String content;
-    };
+    class SourceFile;
 
     // A single translation unit requested to be compiled.
     //
@@ -228,6 +218,10 @@ namespace Slang
         // Are we being driven by the command-line `slangc`, and should act accordingly?
         bool isCommandLineCompile = false;
 
+        // Source manager to help track files loaded
+        SourceManager sourceManagerStorage;
+        SourceManager* sourceManager;
+
         // Output stuff
         DiagnosticSink mSink;
         String mDiagnosticOutput;
@@ -250,12 +244,9 @@ namespace Slang
         Dictionary<String, RefPtr<ModuleDecl>> mapNameToLoadedModules;
 
 
-        CompileRequest(Session* session)
-            : mSession(session)
-        {}
+        CompileRequest(Session* session);
 
-        ~CompileRequest()
-        {}
+        ~CompileRequest();
 
         void parseTranslationUnit(
             TranslationUnitRequest* translationUnit);
@@ -267,6 +258,10 @@ namespace Slang
 
         int addTranslationUnit(SourceLanguage language, String const& name);
 
+        void addTranslationUnitSourceFile(
+            int             translationUnitIndex,
+            SourceFile*     sourceFile);
+
         void addTranslationUnitSourceString(
             int             translationUnitIndex,
             String const&   path,
@@ -285,7 +280,7 @@ namespace Slang
             String const&       name,
             String const&       path,
             String const&       source,
-            CodePosition const& loc);
+            SourceLoc const& loc);
 
         void handlePoundImport(
             String const&       path,
@@ -293,7 +288,18 @@ namespace Slang
 
         RefPtr<ModuleDecl> findOrImportModule(
             String const&       name,
-            CodePosition const& loc);
+            SourceLoc const& loc);
+
+        SourceManager* getSourceManager()
+        {
+            return sourceManager;
+        }
+
+        void setSourceManager(SourceManager* sm)
+        {
+            sourceManager = sm;
+            mSink.sourceManager = sm;
+        }
     };
 
     void generateOutput(
@@ -324,6 +330,9 @@ namespace Slang
 
         List<RefPtr<ModuleDecl>> loadedModuleCode;
 
+        SourceManager   builtinSourceManager;
+
+        SourceManager* getBuiltinSourceManager() { return &builtinSourceManager; }
 
         //