Refactor Stack utility class

wasmx · Sep 2, 2020 · e1e96c6 · e1e96c6
1 parent eacb0ed
commit e1e96c6
Show file tree

Hide file tree

Showing 2 changed files with 60 additions and 130 deletions.
diff --git a/lib/fizzy/stack.hpp b/lib/fizzy/stack.hpp
@@ -13,48 +13,42 @@
 namespace fizzy
 {
 template <typename T>
-class Stack : public std::vector<T>
+class Stack
 {
-public:
-    using difference_type = typename std::vector<T>::difference_type;
-
-    using std::vector<T>::vector;
-
-    using std::vector<T>::back;
-    using std::vector<T>::emplace_back;
-    using std::vector<T>::pop_back;
-    using std::vector<T>::resize;
-    using std::vector<T>::size;
+    std::vector<T> m_container;
 
-    // Also used: size(), resize(), clear(), empty(), end()
-
-    void push(T val) { emplace_back(val); }
+public:
+    void push(T val) { m_container.emplace_back(val); }
 
     template <typename... Args>
     void emplace(Args&&... args)
     {
-        std::vector<T>::emplace_back(std::forward<Args>(args)...);
+        m_container.emplace_back(std::forward<Args>(args)...);
     }
 
-    T pop()
+    T pop() noexcept
     {
-        const auto res = back();
-        pop_back();
+        const auto res = m_container.back();
+        m_container.pop_back();
         return res;
     }
 
-    T& operator[](size_t index) noexcept { return std::vector<T>::operator[](size() - index - 1); }
+    bool empty() const noexcept { return m_container.empty(); }
 
-    T& top() noexcept { return (*this)[0]; }
+    size_t size() const noexcept { return m_container.size(); }
 
-    /// Drops @a num_elements elements from the top of the stack.
-    void drop(size_t num_elements = 1) noexcept { resize(size() - num_elements); }
+    T& operator[](size_t index) noexcept { return m_container[size() - index - 1]; }
+
+    T& top() noexcept { return (*this)[0]; }
 
     void shrink(size_t new_size) noexcept
     {
         assert(new_size <= size());
-        resize(new_size);
+        m_container.resize(new_size);
     }
+
+    /// Drops @a num_elements elements from the top of the stack.
+    void drop(size_t num_elements = 1) noexcept { shrink(size() - num_elements); }
 };
 
 class OperandStack

diff --git a/test/unittests/stack_test.cpp b/test/unittests/stack_test.cpp
@@ -50,7 +50,7 @@ TEST(stack, emplace)
     EXPECT_TRUE(stack.empty());
 }
 
-TEST(stack, drop_and_peek)
+TEST(stack, drop)
 {
     Stack<char> stack;
     stack.push('w');
@@ -80,93 +80,72 @@ TEST(stack, drop_and_peek)
     EXPECT_TRUE(stack.empty());
 }
 
-TEST(stack, clear)
+TEST(stack, shrink)
 {
     Stack<char> stack;
     stack.push('a');
     stack.push('b');
+    stack.push('c');
+    stack.push('d');
+    EXPECT_EQ(stack.top(), 'd');
+    EXPECT_EQ(stack.size(), 4);
 
-    EXPECT_FALSE(stack.empty());
-    EXPECT_EQ(stack.size(), 2);
+    stack.shrink(4);
+    EXPECT_EQ(stack.top(), 'd');
+    EXPECT_EQ(stack.size(), 4);
 
-    stack.drop(0);
-    EXPECT_FALSE(stack.empty());
+    stack.shrink(2);
+    EXPECT_EQ(stack.top(), 'b');
     EXPECT_EQ(stack.size(), 2);
 
-    stack.clear();
+    stack.shrink(0);
     EXPECT_TRUE(stack.empty());
     EXPECT_EQ(stack.size(), 0);
 }
 
-TEST(stack, resize)
+TEST(stack, struct_item)
 {
-    Stack<char> stack;
-    stack.push('a');
-    stack.push('b');
+    struct StackItem
+    {
+        char a, b, c;
+        StackItem() = default;  // required for drop() (which calls resize())
+        StackItem(char _a, char _b, char _c) : a(_a), b(_b), c(_c) {}
+    };
 
-    EXPECT_FALSE(stack.empty());
-    EXPECT_EQ(stack.size(), 2);
+    Stack<StackItem> stack;
 
-    // grow stack
-    stack.resize(4);
-    EXPECT_FALSE(stack.empty());
-    EXPECT_EQ(stack.top(), 0);
-    EXPECT_EQ(stack[1], 0);
-    EXPECT_EQ(stack[2], 'b');
-    EXPECT_EQ(stack[3], 'a');
-    EXPECT_EQ(stack.size(), 4);
+    stack.emplace('a', 'b', 'c');
+    stack.emplace('d', 'e', 'f');
+    stack.emplace('g', 'h', 'i');
 
-    stack.drop();
-    EXPECT_FALSE(stack.empty());
     EXPECT_EQ(stack.size(), 3);
 
-    // shrink stack
-    stack.resize(1);
-    EXPECT_FALSE(stack.empty());
-    EXPECT_EQ(stack.size(), 1);
-
-    stack.clear();
-    EXPECT_TRUE(stack.empty());
-    EXPECT_EQ(stack.size(), 0);
-
-    // resize and shrink
-    stack.resize(4);
-    EXPECT_EQ(stack.size(), 4);
-    stack.shrink(2);
-    EXPECT_EQ(stack.size(), 2);
-    stack.shrink(0);
-    EXPECT_TRUE(stack.empty());
-    EXPECT_EQ(stack.size(), 0);
-}
-
-TEST(stack, iterator)
-{
-    Stack<char> stack;
-    stack.push('a');
-    stack.push('b');
-    stack.push('c');
-
-    EXPECT_FALSE(stack.empty());
-    EXPECT_EQ(stack.size(), 3);
+    EXPECT_EQ(stack.top().a, 'g');
+    EXPECT_EQ(stack.top().b, 'h');
+    EXPECT_EQ(stack.top().c, 'i');
+    EXPECT_EQ(stack[1].a, 'd');
+    EXPECT_EQ(stack[1].b, 'e');
+    EXPECT_EQ(stack[1].c, 'f');
+    EXPECT_EQ(stack[2].a, 'a');
+    EXPECT_EQ(stack[2].b, 'b');
+    EXPECT_EQ(stack[2].c, 'c');
 
-    auto bottom_item = stack.begin();
-    EXPECT_EQ(*bottom_item, 'a');
+    EXPECT_EQ(stack.pop().a, 'g');
 
-    auto top_item = stack.end() - 1;
-    EXPECT_EQ(*top_item, 'c');
+    EXPECT_EQ(stack.top().a, 'd');
+    EXPECT_EQ(stack.top().b, 'e');
+    EXPECT_EQ(stack.top().c, 'f');
+    EXPECT_EQ(stack[1].a, 'a');
+    EXPECT_EQ(stack[1].b, 'b');
+    EXPECT_EQ(stack[1].c, 'c');
 
-    for (auto it = stack.begin(); it < stack.end(); it++)
-        *it = 'x';
+    stack.drop();
 
-    for (unsigned item = 0; item < stack.size(); item++)
-        EXPECT_EQ(stack[item], 'x');
+    EXPECT_EQ(stack.top().a, 'a');
+    EXPECT_EQ(stack.top().b, 'b');
+    EXPECT_EQ(stack.top().c, 'c');
 }
 
-TEST(stack, clear_on_empty)
-{
-    Stack<char> stack;
-    stack.clear();
-}
 
 TEST(operand_stack, construct)
 {
@@ -287,46 +266,3 @@ TEST(operand_stack, to_vector)
     EXPECT_EQ(result[1].i64, 2);
     EXPECT_EQ(result[2].i64, 3);
 }
-
-TEST(stack, struct_item)
-{
-    struct StackItem
-    {
-        char a, b, c;
-        StackItem() = default;  // required for drop() (which calls resize())
-        StackItem(char _a, char _b, char _c) : a(_a), b(_b), c(_c) {}
-    };
-
-    Stack<StackItem> stack;
-
-    stack.emplace('a', 'b', 'c');
-    stack.emplace('d', 'e', 'f');
-    stack.emplace('g', 'h', 'i');
-
-    EXPECT_EQ(stack.size(), 3);
-
-    EXPECT_EQ(stack.top().a, 'g');
-    EXPECT_EQ(stack.top().b, 'h');
-    EXPECT_EQ(stack.top().c, 'i');
-    EXPECT_EQ(stack[1].a, 'd');
-    EXPECT_EQ(stack[1].b, 'e');
-    EXPECT_EQ(stack[1].c, 'f');
-    EXPECT_EQ(stack[2].a, 'a');
-    EXPECT_EQ(stack[2].b, 'b');
-    EXPECT_EQ(stack[2].c, 'c');
-
-    EXPECT_EQ(stack.pop().a, 'g');
-
-    EXPECT_EQ(stack.top().a, 'd');
-    EXPECT_EQ(stack.top().b, 'e');
-    EXPECT_EQ(stack.top().c, 'f');
-    EXPECT_EQ(stack[1].a, 'a');
-    EXPECT_EQ(stack[1].b, 'b');
-    EXPECT_EQ(stack[1].c, 'c');
-
-    stack.drop();
-
-    EXPECT_EQ(stack.top().a, 'a');
-    EXPECT_EQ(stack.top().b, 'b');
-    EXPECT_EQ(stack.top().c, 'c');
-}