WastParser: replace CircularArray with internal TokenQueue (NFC) (#2300)

2 files changed, 16 insertions, 125 deletions

diff --git a/include/wabt/circular-array.h b/include/wabt/circular-array.h
deleted file mode 100644
index 9e2d3800..00000000
--- a/include/wabt/circular-array.h
+++ /dev/null
@@ -1,123 +0,0 @@
-/*
- * Copyright 2017 WebAssembly Community Group participants
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef WABT_CIRCULAR_ARRAY_H_
-#define WABT_CIRCULAR_ARRAY_H_
-
-#include <array>
-#include <cassert>
-#include <cstddef>
-#include <type_traits>
-
-namespace wabt {
-
-// TODO(karlschimpf) Complete the API
-// Note: Capacity must be a power of 2.
-template <class T, size_t kCapacity>
-class CircularArray {
- public:
-  using value_type = T;
-  using reference = value_type&;
-  using const_reference = const value_type&;
-  using size_type = size_t;
-  using difference_type = ptrdiff_t;
-
-  CircularArray() {
-    static_assert(kCapacity && ((kCapacity & (kCapacity - 1)) == 0),
-                  "Capacity must be a power of 2.");
-  }
-
-  CircularArray(const CircularArray&) = default;
-  CircularArray& operator=(const CircularArray&) = default;
-
-  CircularArray(CircularArray&&) = default;
-  CircularArray& operator=(CircularArray&&) = default;
-
-  ~CircularArray() { clear(); }
-
-  reference at(size_type index) {
-    assert(index < size_);
-    return (*this)[index];
-  }
-
-  const_reference at(size_type index) const {
-    assert(index < size_);
-    return (*this)[index];
-  }
-
-  reference operator[](size_type index) { return contents_[position(index)]; }
-
-  const_reference operator[](size_type index) const {
-    return contents_[position(index)];
-  }
-
-  reference back() { return at(size_ - 1); }
-
-  const_reference back() const { return at(size_ - 1); }
-
-  bool empty() const { return size_ == 0; }
-
-  reference front() { return at(0); }
-
-  const_reference front() const { return at(0); }
-
-  size_type max_size() const { return kCapacity; }
-
-  void pop_back() {
-    assert(size_ > 0);
-    SetElement(back());
-    --size_;
-  }
-
-  void pop_front() {
-    assert(size_ > 0);
-    SetElement(front());
-    front_ = (front_ + 1) & kMask;
-    --size_;
-  }
-
-  void push_back(const value_type& value) {
-    assert(size_ < kCapacity);
-    SetElement(at(size_++), value);
-  }
-
-  size_type size() const { return size_; }
-
-  void clear() {
-    while (!empty()) {
-      pop_back();
-    }
-  }
-
- private:
-  static constexpr size_type kMask = kCapacity - 1;
-
-  size_t position(size_t index) const { return (front_ + index) & kMask; }
-
-  template <typename... Args>
-  void SetElement(reference element, Args&&... args) {
-    element.~T();
-    new (&element) T(std::forward<Args>(args)...);
-  }
-
-  std::array<T, kCapacity> contents_;
-  size_type size_ = 0;
-  size_type front_ = 0;
-};
-
-}  // namespace wabt
-
-#endif  // WABT_CIRCULAR_ARRAY_H_
diff --git a/include/wabt/wast-parser.h b/include/wabt/wast-parser.h
index 9464147d..36447c58 100644
--- a/include/wabt/wast-parser.h
+++ b/include/wabt/wast-parser.h
@@ -19,9 +19,9 @@
 
 #include <array>
 #include <memory>
+#include <optional>
 #include <unordered_map>
 
-#include "wabt/circular-array.h"
 #include "wabt/error.h"
 #include "wabt/feature.h"
 #include "wabt/intrusive-list.h"
@@ -262,7 +262,21 @@ class WastParser {
   Errors* errors_;
   WastParseOptions* options_;
 
-  CircularArray<Token, 2> tokens_;
+  // two-element queue of upcoming tokens
+  class TokenQueue {
+    std::array<std::optional<Token>, 2> tokens{};
+    bool i{};
+
+   public:
+    void push_back(Token t);
+    void pop_front();
+    const Token& at(size_t n) const;
+    const Token& front() const;
+    bool empty() const;
+    size_t size() const;
+  };
+
+  TokenQueue tokens_{};
 };
 
 Result ParseWatModule(WastLexer* lexer,