[libc-commits] [libc] [libc] Implement strftime (PR #122556)

[Michael Jones via libc-commits]

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+//===-- Unittests for strftime --------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "hdr/types/struct_tm.h"
+#include "src/__support/CPP/array.h"
+#include "src/__support/integer_to_string.h"
+#include "src/time/strftime.h"
+#include "src/time/time_constants.h"
+#include "test/UnitTest/Test.h"
+
+// Copied from sprintf_test.cpp.
+// TODO: put this somewhere more reusable, it's handy.
+// Subtract 1 from sizeof(expected_str) to account for the null byte.
+#define EXPECT_STREQ_LEN(actual_written, actual_str, expected_str)             \
+  EXPECT_EQ(actual_written, sizeof(expected_str) - 1);                         \
+  EXPECT_STREQ(actual_str, expected_str);
+
+constexpr int get_adjusted_year(int year) {
+  // tm_year counts years since 1900, so subtract 1900 to get the tm_year for a
+  // given raw year.
+  return year - LIBC_NAMESPACE::time_constants::TIME_YEAR_BASE;
+}
+
+// TODO: Move this somewhere it can be reused. It seems like a useful tool to
+// have.
+// A helper class to generate simple padded numbers. It places the result in its
+// internal buffer, which is cleared on every call.
+class SimplePaddedNum {
+  static constexpr size_t BUFF_LEN = 16;
+  char buff[BUFF_LEN];
+  size_t cur_len; // length of string currently in buff
+
+  void clear_buff() {
+    // TODO: builtin_memset?
+    for (size_t i = 0; i < BUFF_LEN; ++i)
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michaelrj-google wrote:

yeah, but if we use the proper name for `memset` we have to include the header. That's why I left this as a todo.

https://github.com/llvm/llvm-project/pull/122556