[libc] Add strtok implementation.

Reviewed By: sivachandra

Differential Revision: https://reviews.llvm.org/D85615

2 files changed, 88 insertions, 0 deletions

diff --git a/libc/test/src/string/CMakeLists.txt b/libc/test/src/string/CMakeLists.txt
index f7c580dd1876..8dfffa65175c 100644
--- a/libc/test/src/string/CMakeLists.txt
+++ b/libc/test/src/string/CMakeLists.txt
@@ -132,6 +132,16 @@ add_libc_unittest(
     libc.src.string.strpbrk
 )
 
+add_libc_unittest(
+  strtok_test
+  SUITE
+    libc_string_unittests
+  SRCS
+    strtok_test.cpp
+  DEPENDS
+    libc.src.string.strtok
+)
+
 # Tests all implementations that can run on the host.
 function(add_libc_multi_impl_test name)
   get_property(fq_implementations GLOBAL PROPERTY ${name}_implementations)
diff --git a/libc/test/src/string/strtok_test.cpp b/libc/test/src/string/strtok_test.cpp
new file mode 100644
index 000000000000..311b9cf28fd4
--- /dev/null
+++ b/libc/test/src/string/strtok_test.cpp
@@ -0,0 +1,78 @@
+//===-- Unittests for strtok ---------------------------------------------===//
+//
+// 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 "src/string/strtok.h"
+#include "utils/UnitTest/Test.h"
+
+TEST(StrTokTest, NoTokenFound) {
+  char empty[] = "";
+  ASSERT_STREQ(__llvm_libc::strtok(empty, ""), nullptr);
+  ASSERT_STREQ(__llvm_libc::strtok(empty, "_"), nullptr);
+
+  char single[] = "_";
+  ASSERT_STREQ(__llvm_libc::strtok(single, ""), "_");
+
+  char multiple[] = "1,2";
+  ASSERT_STREQ(__llvm_libc::strtok(multiple, ":"), "1,2");
+}
+
+TEST(StrTokTest, DelimiterAsFirstCharacterShouldBeIgnored) {
+  char src[] = ".123";
+  ASSERT_STREQ(__llvm_libc::strtok(src, "."), "123");
+}
+
+TEST(StrTokTest, DelimiterIsMiddleCharacter) {
+  char src[] = "12,34";
+  ASSERT_STREQ(__llvm_libc::strtok(src, ","), "12");
+}
+
+TEST(StrTokTest, DelimiterAsLastCharacterShouldBeIgnored) {
+  char src[] = "1234:";
+  ASSERT_STREQ(__llvm_libc::strtok(src, ":"), "1234");
+}
+
+TEST(StrTokTest, MultipleDelimiters) {
+  char src[] = "12,.34";
+  ASSERT_STREQ(__llvm_libc::strtok(src, "."), "12,");
+  ASSERT_STREQ(__llvm_libc::strtok(src, ".,"), "12");
+  ASSERT_STREQ(__llvm_libc::strtok(src, ",."), "12");
+  ASSERT_STREQ(__llvm_libc::strtok(src, ":,."), "12");
+}
+
+TEST(StrTokTest, ShouldNotGoPastNullTerminator) {
+  char src[] = {'1', '2', '\0', ',', '3'};
+  ASSERT_STREQ(__llvm_libc::strtok(src, ","), "12");
+}
+
+TEST(StrTokTest, SubsequentCallsShouldFindFollowingDelimiters) {
+  char src[] = "12,34.56";
+  char *token = __llvm_libc::strtok(src, ",.");
+  ASSERT_STREQ(token, "12");
+  token = __llvm_libc::strtok(nullptr, ",.");
+  ASSERT_STREQ(token, "34");
+  token = __llvm_libc::strtok(nullptr, ",.");
+  ASSERT_STREQ(token, "56");
+  token = __llvm_libc::strtok(nullptr, "_:,_");
+  ASSERT_STREQ(token, nullptr);
+  // Subsequent calls after hitting the end of the string should also return
+  // nullptr.
+  token = __llvm_libc::strtok(nullptr, "_:,_");
+  ASSERT_STREQ(token, nullptr);
+}
+
+TEST(StrTokTest, DelimitersShouldNotBeIncludedInToken) {
+  char src[] = "__ab__:_cd__:__ef__:__";
+  char *token = __llvm_libc::strtok(src, "_:");
+  ASSERT_STREQ(token, "ab");
+  token = __llvm_libc::strtok(nullptr, ":_");
+  ASSERT_STREQ(token, "cd");
+  token = __llvm_libc::strtok(nullptr, "_:,");
+  ASSERT_STREQ(token, "ef");
+  token = __llvm_libc::strtok(nullptr, "_:,_");
+  ASSERT_STREQ(token, nullptr);
+}