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

[Justin Bogner via llvm-branch-commits]

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@@ -80,6 +85,99 @@ class RootSignatureLexer {
   }
 };
 
+class RootSignatureParser {
+public:
+  RootSignatureParser(SmallVector<rs::RootElement> &Elements,
+                      const SmallVector<RootSignatureToken> &Tokens,
+                      DiagnosticsEngine &Diags);
+
+  // Iterates over the provided tokens and constructs the in-memory
+  // representations of the RootElements.
+  //
+  // The return value denotes if there was a failure and the method will
+  // return on the first encountered failure, or, return false if it
+  // can sucessfully reach the end of the tokens.
+  bool Parse();
+
+private:
+  // Root Element helpers
+  bool ParseRootElement(bool First);
+  bool ParseDescriptorTable();
+  bool ParseDescriptorTableClause();
+
+  // Helper dispatch method
+  //
+  // These will switch on the Variant kind to dispatch to the respective Parse
+  // method and store the parsed value back into Ref.
+  //
+  // It is helpful to have a generalized dispatch method so that when we need
+  // to parse multiple optional parameters in any order, we can invoke this
+  // method
+  bool ParseParam(rs::ParamType Ref);
+
+  // Parse as many optional parameters as possible in any order
+  bool
+  ParseOptionalParams(llvm::SmallDenseMap<TokenKind, rs::ParamType> RefMap);
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bogner wrote:

Do you really want to be passing a `SmallDenseMap` by value here? This and the other similar APIs should probably be using references.

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