tint: Add new methods to semantic Switch nodes

• Add sem::SwitchStatement::Cases()
• Add sem::CaseStatement::Selectors()
• Add ast::SwitchStatement -> sem::SwitchStatement mapping

Removes a bunch of hopping between the AST and SEM to get at this data.

Change-Id: If48d78e7a386aa0b34c6d00ad9af1d53cb236f12
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/91024
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>

src/tint/sem/switch_statement.h

@@ -15,6 +15,8 @@
 #ifndef SRC_TINT_SEM_SWITCH_STATEMENT_H_
 #define SRC_TINT_SEM_SWITCH_STATEMENT_H_
 
+#include <vector>
+
 #include "src/tint/sem/block_statement.h"
 
 // Forward declarations
@@ -22,6 +24,10 @@ namespace tint::ast {
 class CaseStatement;
 class SwitchStatement;
 }  // namespace tint::ast
+namespace tint::sem {
+class CaseStatement;
+class Expression;
+}  // namespace tint::sem
 
 namespace tint::sem {
 
@@ -41,6 +47,15 @@ class SwitchStatement final : public Castable<SwitchStatement, CompoundStatement
 
     /// @return the AST node for this statement
     const ast::SwitchStatement* Declaration() const;
+
+    /// @returns the case statements for this switch
+    std::vector<const CaseStatement*>& Cases() { return cases_; }
+
+    /// @returns the case statements for this switch
+    const std::vector<const CaseStatement*>& Cases() const { return cases_; }
+
+  private:
+    std::vector<const CaseStatement*> cases_;
 };
 
 /// Holds semantic information about a switch case statement
@@ -66,8 +81,15 @@ class CaseStatement final : public Castable<CaseStatement, CompoundStatement> {
     /// @returns the case body block statement
     const BlockStatement* Body() const { return body_; }
 
+    /// @returns the selectors for the case
+    std::vector<const Expression*>& Selectors() { return selectors_; }
+
+    /// @returns the selectors for the case
+    const std::vector<const Expression*>& Selectors() const { return selectors_; }
+
   private:
     const BlockStatement* body_ = nullptr;
+    std::vector<const Expression*> selectors_;
 };
 
 }  // namespace tint::sem

src/tint/sem/type_mappings.h

@@ -30,6 +30,7 @@ class Node;
 class Statement;
 class Struct;
 class StructMember;
+class SwitchStatement;
 class Type;
 class TypeDecl;
 class Variable;
@@ -46,6 +47,7 @@ class Node;
 class Statement;
 class Struct;
 class StructMember;
+class SwitchStatement;
 class Type;
 class Variable;
 }  // namespace tint::sem
@@ -68,6 +70,7 @@ struct TypeMappings {
     Statement* operator()(ast::Statement*);
     Struct* operator()(ast::Struct*);
     StructMember* operator()(ast::StructMember*);
+    SwitchStatement* operator()(ast::SwitchStatement*);
     Type* operator()(ast::Type*);
     Type* operator()(ast::TypeDecl*);
     Variable* operator()(ast::Variable*);