From 619def44c1cca9f3cdf63544d5f24f2c7a7d9b77 Mon Sep 17 00:00:00 2001
From: Klaus Aehlig <klaus.aehlig@huawei.com>
Date: Tue, 22 Feb 2022 17:03:21 +0100
Subject: Initial self-hosting commit

This is the initial version of our tool that is able to
build itself. In can be bootstrapped by

  ./bin/bootstrap.py

Co-authored-by: Oliver Reiche <oliver.reiche@huawei.com>
Co-authored-by: Victor Moreno <victor.moreno1@huawei.com>
---
 .../build_engine/expression/evaluator.hpp          | 76 ++++++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 src/buildtool/build_engine/expression/evaluator.hpp

(limited to 'src/buildtool/build_engine/expression/evaluator.hpp')

diff --git a/src/buildtool/build_engine/expression/evaluator.hpp b/src/buildtool/build_engine/expression/evaluator.hpp
new file mode 100644
index 00000000..b4cd5979
--- /dev/null
+++ b/src/buildtool/build_engine/expression/evaluator.hpp
@@ -0,0 +1,76 @@
+#ifndef INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_EXPRESSION_EVALUATOR_HPP
+#define INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_EXPRESSION_EVALUATOR_HPP
+
+#include <exception>
+#include <string>
+
+#include "src/buildtool/build_engine/expression/expression.hpp"
+#include "src/buildtool/build_engine/expression/function_map.hpp"
+
+class Configuration;
+
+class Evaluator {
+  public:
+    class EvaluationError : public std::exception {
+      public:
+        explicit EvaluationError(std::string const& msg,
+                                 bool while_eval = false,
+                                 bool user_context = false) noexcept
+            : msg_{(while_eval ? ""
+                               : (user_context ? "UserError: "
+                                               : "EvaluationError: ")) +
+                   msg},
+              while_eval_{while_eval},
+              user_context_{user_context} {}
+        [[nodiscard]] auto what() const noexcept -> char const* final {
+            return msg_.c_str();
+        }
+
+        [[nodiscard]] auto WhileEvaluation() const -> bool {
+            return while_eval_;
+        }
+
+        [[nodiscard]] auto UserContext() const -> bool { return user_context_; }
+
+        [[nodiscard]] static auto WhileEvaluating(ExpressionPtr const& expr,
+                                                  Configuration const& env,
+                                                  std::exception const& ex)
+            -> EvaluationError;
+
+        [[nodiscard]] static auto WhileEval(ExpressionPtr const& expr,
+                                            Configuration const& env,
+                                            EvaluationError const& ex)
+            -> EvaluationError;
+
+        [[nodiscard]] static auto WhileEvaluating(const std::string& where,
+                                                  std::exception const& ex)
+            -> Evaluator::EvaluationError;
+
+        [[nodiscard]] static auto WhileEval(const std::string& where,
+                                            EvaluationError const& ex)
+            -> Evaluator::EvaluationError;
+
+      private:
+        std::string msg_;
+        bool while_eval_;
+        bool user_context_;
+    };
+
+    // Exception-free evaluation of expression
+    [[nodiscard]] static auto EvaluateExpression(
+        ExpressionPtr const& expr,
+        Configuration const& env,
+        FunctionMapPtr const& provider_functions,
+        std::function<void(std::string const&)> const& logger,
+        std::function<void(void)> const& note_user_context = []() {}) noexcept
+        -> ExpressionPtr;
+
+  private:
+    constexpr static std::size_t kLineWidth = 80;
+    [[nodiscard]] static auto Evaluate(ExpressionPtr const& expr,
+                                       Configuration const& env,
+                                       FunctionMapPtr const& functions)
+        -> ExpressionPtr;
+};
+
+#endif  // INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_EXPRESSION_EVALUATOR_HPP
-- 
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