[FixedString] Implement resize()

teslamotors · Sep 26, 2023 · a524b9f · a524b9f
1 parent 7da242e
commit a524b9f
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diff --git a/include/fixed_containers/fixed_string.hpp b/include/fixed_containers/fixed_string.hpp
@@ -88,6 +88,16 @@ class FixedString
     using reverse_iterator = typename FixedVecStorage::reverse_iterator;
     using const_reverse_iterator = typename FixedVecStorage::const_reverse_iterator;
 
+private:
+    static constexpr void check_target_length(size_type target_length,
+                                              const std_transition::source_location& loc)
+    {
+        if (preconditions::test(target_length <= MAXIMUM_LENGTH))
+        {
+            Checking::length_error(target_length, loc);
+        }
+    }
+
 public:  // Public so this type is a structural type and can thus be used in template parameters
     FixedVecStorage IMPLEMENTATION_DETAIL_DO_NOT_USE_data_;
 
@@ -445,6 +455,29 @@ class FixedString
         return std::string_view(*this).substr(pos, len);
     }
 
+    constexpr void resize(
+        size_type count,
+        const std_transition::source_location& loc = std_transition::source_location::current())
+    {
+        resize(count, CharT{}, loc);
+    }
+
+    constexpr void resize(
+        size_type count,
+        CharT ch,
+        const std_transition::source_location& loc = std_transition::source_location::current())
+    {
+        if (ch == CharT{} && count > length())
+        {
+            // Before `count` is shrinked, ensure it is not too big
+            check_target_length(count, loc);
+            count = length();
+        }
+
+        vec().resize(count, ch, loc);
+        null_terminate(loc);
+    }
+
 private:
     constexpr void null_terminate(std::size_t n)
     {

diff --git a/test/fixed_string_test.cpp b/test/fixed_string_test.cpp
@@ -1406,4 +1406,59 @@ TEST(FixedString, Substring)
     EXPECT_DEATH((void)v1.substr(5, 1), "");
 }
 
+TEST(FixedString, Resize)
+{
+    constexpr auto v1 = []()
+    {
+        FixedString<7> v{"012"};
+        v.resize(6);  // This won't add extra null-terminators
+        return v;
+    }();
+
+    static_assert(v1[0] == '0');
+    static_assert(v1[1] == '1');
+    static_assert(v1[2] == '2');
+    static_assert(v1.size() == 3);
+    static_assert(v1.max_size() == 7);
+
+    constexpr auto v2 = []()
+    {
+        FixedString<7> v{"012"};
+        v.resize(7, 'c');
+        v[4] = 'x';
+        v.resize(5, 'e');
+        return v;
+    }();
+
+    static_assert(v2[0] == '0');
+    static_assert(v2[1] == '1');
+    static_assert(v2[2] == '2');
+    static_assert(v2[3] == 'c');
+    static_assert(v2[4] == 'x');
+    static_assert(v2.size() == 5);
+    static_assert(v2.max_size() == 7);
+
+    FixedString<8> v3{"0123"};
+    v3.resize(6);  // This won't add extra null-terminators
+
+    EXPECT_EQ(v3, "0123");
+
+    v3.resize(2);
+    EXPECT_EQ(v3, "01");
+
+    v3.resize(5, '3');
+
+    EXPECT_EQ(v3, "01333");
+}
+
+TEST(FixedString, Resize_ExceedCapacity)
+{
+    FixedString<3> v1{};
+    EXPECT_DEATH(v1.resize(6), "");
+    EXPECT_DEATH(v1.resize(6, 5), "");
+    const size_t to_size = 7;
+    EXPECT_DEATH(v1.resize(to_size), "");
+    EXPECT_DEATH(v1.resize(to_size, 5), "");
+}
+
 }  // namespace fixed_containers