[clang] [llvm] [HLSL][RootSignature] Implement Parsing of Descriptor Tables (PR #122982)

[Finn Plummer via cfe-commits]

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@@ -162,5 +219,371 @@ std::optional<RootSignatureToken> RootSignatureLexer::PeekNextToken() {
   return Result;
 }
 
+// Parser Definitions
+
+RootSignatureParser::RootSignatureParser(SmallVector<RootElement> &Elements,
+                                         RootSignatureLexer &Lexer,
+                                         DiagnosticsEngine &Diags)
+    : Elements(Elements), Lexer(Lexer), Diags(Diags) {}
+
+bool RootSignatureParser::Parse() {
+  // Handle edge-case of empty RootSignature()
+  if (Lexer.EndOfBuffer())
+    return false;
+
+  // Iterate as many RootElements as possible
+  while (!ParseRootElement()) {
+    if (Lexer.EndOfBuffer())
+      return false;
+    if (ConsumeExpectedToken(TokenKind::pu_comma))
+      return true;
+  }
+
+  return true;
+}
+
+bool RootSignatureParser::ParseRootElement() {
+  if (ConsumeExpectedToken(TokenKind::kw_DescriptorTable))
+    return true;
+
+  // Dispatch onto the correct parse method
+  switch (CurToken.Kind) {
+  case TokenKind::kw_DescriptorTable:
+    return ParseDescriptorTable();
+  default:
+    llvm_unreachable("Switch for an expected token was not provided");
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inbelic wrote:

At the moment, we follow the pattern of `ConsumeExpectedToken({TokenKind1, ..., TokenKindN})` and then switch on the token kinds that were in that statement. `ConsumeExpectedToken` guards against any other token kind. So any new token kind is added we will never reach the default here, unless it is also added to the `ConsumeExpectedToken` statement.

Maybe there is a way we could define the macros to generate sub-sets of tokens? Although, I am of the opinion the current method guards against this sufficiently.



https://github.com/llvm/llvm-project/pull/122982