Add type determiner infrastructure.

This CL adds the Context object, variable ScopeStack and a Function map
into the type determiner.

The sample app is also updated to verify the module produced before
passing to the type determiner.

Bug: tint:5
Change-Id: Ib4af4e4305ee8a306f48e1bd328eaf3ad006fd9a
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/18823
Reviewed-by: David Neto <dneto@google.com>

src/type_determiner.cc

@@ -16,7 +16,10 @@
 
 namespace tint {
 
-TypeDeterminer::TypeDeterminer() = default;
+TypeDeterminer::TypeDeterminer(Context* ctx) : ctx_(*ctx) {
+  // TODO(dsinclair): Temporary usage to avoid compiler warning
+  static_cast<void>(ctx_.type_mgr());
+}
 
 TypeDeterminer::~TypeDeterminer() = default;
 

src/type_determiner.h

@@ -16,16 +16,26 @@
 #define SRC_TYPE_DETERMINER_H_
 
 #include <string>
+#include <unordered_map>
 
 #include "src/ast/module.h"
+#include "src/context.h"
+#include "src/scope_stack.h"
 
 namespace tint {
+namespace ast {
+
+class Function;
+class Variable;
+
+}  // namespace ast
 
 /// Determines types for all items in the given tint module
 class TypeDeterminer {
  public:
   /// Constructor
-  TypeDeterminer();
+  /// @param ctx the tint context
+  explicit TypeDeterminer(Context* ctx);
   ~TypeDeterminer();
 
   /// Runs the type determiner
@@ -37,7 +47,10 @@ class TypeDeterminer {
   const std::string& error() { return error_; }
 
  private:
+  Context& ctx_;
   std::string error_;
+  ScopeStack<ast::Variable*> variable_stack_;
+  std::unordered_map<std::string, ast::Function*> name_to_function_;
 };
 
 }  // namespace tint