Data-driven parsing of modifiers

Just like the previous change did for declaration keywords, this change uses the lexical environment to drive the lookup and dispatch of modifier parsing.
This allows us to easily add modifiers to Slang, even when they might conflict with identifiers used in user code (because the modifier names are no longer special keywords, but ordinary identifiers).

There was already some support for ideas like this with `__modifier` declarations (`ModifierDecl`) used to introduce some GLSL-specific keywords (so that they wouldn't pollute the namespace of HLSL files).
The new approach changes these to be actual `syntax` declarations (`SyntaxDecl`) with the same representation as those used to introduce declaration keywords.

Because many modifiers just introduce a single keyword that maps to a simple AST node (no further tokens/data), I modified the handling of syntax declarations so that they can take a user-data parameter, and this allows the common case ("just create an AST node of this type...") to be handled with minimal complications.

This also adds in a general-purpose string-based lookup path for AST node classes, that should support programmatic creation in more cases.

Statements are now the main case of keywords that need to be made table driven.

1 files changed, 0 insertions, 5 deletions

diff --git a/source/slang/check.cpp b/source/slang/check.cpp
index 9f7a13230..bb0b1b794 100644
--- a/source/slang/check.cpp
+++ b/source/slang/check.cpp
@@ -1202,11 +1202,6 @@ namespace Slang
             // These are only used in the stdlib, so no checking is needed
         }
 
-        void visitModifierDecl(ModifierDecl*)
-        {
-            // These are only used in the stdlib, so no checking is needed
-        }
-
         void visitGenericTypeParamDecl(GenericTypeParamDecl*)
         {
             // These are only used in the stdlib, so no checking is needed for now