[clang] [HLSL][RootSignature] Implement Lexing of DescriptorTables (PR #122981)

[Damyan Pepper via cfe-commits]

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@@ -0,0 +1,171 @@
+#include "clang/Parse/ParseHLSLRootSignature.h"
+
+namespace clang {
+namespace hlsl {
+
+// Lexer Definitions
+
+static bool IsNumberChar(char C) {
+  // TODO(#120472): extend for float support exponents
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damyanp wrote:

The issue linked here (#120472) is just about implementing the parser. Is there a reason not to get float tokens recognized by the lexer?

https://github.com/llvm/llvm-project/pull/122981