[libc-commits] [libc] d080635 - [libc] Add strstr implementation.
via libc-commits
libc-commits at lists.llvm.org
Tue Jul 21 08:39:38 PDT 2020
Author: cgyurgyik
Date: 2020-07-21T11:39:23-04:00
New Revision: d080635bfca25e66edd5c5dd333bbd1f8eb70a77
URL: https://github.com/llvm/llvm-project/commit/d080635bfca25e66edd5c5dd333bbd1f8eb70a77
DIFF: https://github.com/llvm/llvm-project/commit/d080635bfca25e66edd5c5dd333bbd1f8eb70a77.diff
LOG: [libc] Add strstr implementation.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D83956
Added:
libc/src/string/strstr.cpp
libc/src/string/strstr.h
libc/test/src/string/strstr_test.cpp
Modified:
libc/config/linux/aarch64/entrypoints.txt
libc/config/linux/x86_64/entrypoints.txt
libc/src/string/CMakeLists.txt
libc/test/src/string/CMakeLists.txt
Removed:
################################################################################
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 5d607b82892f..74834d19bce8 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -11,6 +11,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.string.strlen
libc.src.string.memchr
libc.src.string.strchr
+ libc.str.string.strstr
)
set(TARGET_LIBM_ENTRYPOINTS
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index fc62fbb880b4..f08f775cd892 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -29,6 +29,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.string.strcmp
libc.src.string.memchr
libc.src.string.strchr
+ libc.src.string.strstr
# sys/mman.h entrypoints
libc.src.sys.mman.mmap
diff --git a/libc/src/string/CMakeLists.txt b/libc/src/string/CMakeLists.txt
index c8e1e4dfa39f..98693ccc0598 100644
--- a/libc/src/string/CMakeLists.txt
+++ b/libc/src/string/CMakeLists.txt
@@ -60,6 +60,14 @@ add_entrypoint_object(
strchr.h
)
+add_entrypoint_object(
+ strstr
+ SRCS
+ strstr.cpp
+ HDRS
+ strstr.h
+)
+
# Helper to define a function with multiple implementations
# - Computes flags to satisfy required/rejected features and arch,
# - Declares an entry point,
diff --git a/libc/src/string/strstr.cpp b/libc/src/string/strstr.cpp
new file mode 100644
index 000000000000..a598f6610621
--- /dev/null
+++ b/libc/src/string/strstr.cpp
@@ -0,0 +1,29 @@
+//===-- Implementation of strstr ------------------------------------------===//
+//
+// 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/strstr.h"
+
+#include "src/__support/common.h"
+#include <stddef.h>
+
+namespace __llvm_libc {
+
+// TODO: This is a simple brute force implementation. This can be
+// improved upon using well known string matching algorithms.
+char *LLVM_LIBC_ENTRYPOINT(strstr)(const char *haystack, const char *needle) {
+ for (size_t i = 0; haystack[i]; ++i) {
+ size_t j;
+ for (j = 0; haystack[i + j] && haystack[i + j] == needle[j]; ++j)
+ ;
+ if (!needle[j])
+ return const_cast<char *>(haystack + i);
+ }
+ return nullptr;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/string/strstr.h b/libc/src/string/strstr.h
new file mode 100644
index 000000000000..463ffb7494c9
--- /dev/null
+++ b/libc/src/string/strstr.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for strstr ------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_STRING_STRSTR_H
+#define LLVM_LIBC_SRC_STRING_STRSTR_H
+
+namespace __llvm_libc {
+
+char *strstr(const char *haystack, const char *needle);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STRING_STRSTR_H
diff --git a/libc/test/src/string/CMakeLists.txt b/libc/test/src/string/CMakeLists.txt
index be4836818212..81ae08d7249a 100644
--- a/libc/test/src/string/CMakeLists.txt
+++ b/libc/test/src/string/CMakeLists.txt
@@ -62,6 +62,16 @@ add_libc_unittest(
libc.src.string.strchr
)
+add_libc_unittest(
+ strstr_test
+ SUITE
+ libc_string_unittests
+ SRCS
+ strstr_test.cpp
+ DEPENDS
+ libc.src.string.strstr
+)
+
# 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/strstr_test.cpp b/libc/test/src/string/strstr_test.cpp
new file mode 100644
index 000000000000..f4edbb2cca59
--- /dev/null
+++ b/libc/test/src/string/strstr_test.cpp
@@ -0,0 +1,114 @@
+//===-- Unittests for strstr ----------------------------------------------===//
+//
+// 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/strstr.h"
+#include "utils/UnitTest/Test.h"
+
+TEST(StrStrTest, NeedleNotInHaystack) {
+ const char *haystack = "12345";
+ const char *needle = "a";
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, needle), nullptr);
+}
+
+TEST(StrStrTest, NeedleIsEmptyString) {
+ const char *haystack = "12345";
+ const char *needle = "";
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, needle), haystack);
+}
+
+TEST(StrStrTest, HaystackIsEmptyString) {
+ const char *haystack = "";
+ const char *needle = "12345";
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, needle), nullptr);
+}
+
+TEST(StrStrTest, HaystackAndNeedleAreEmptyStrings) {
+ const char *haystack = "";
+ const char *needle = "";
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, needle), "");
+}
+
+TEST(StrStrTest, HaystackAndNeedleAreSingleCharacters) {
+ const char *haystack = "a";
+ // Same characer returns that character.
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, /*needle=*/"a"), "a");
+ // Different character returns nullptr.
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, /*needle=*/"b"), nullptr);
+}
+
+TEST(StrStrTest, NeedleEqualToHaystack) {
+ const char *haystack = "12345";
+ const char *needle = "12345";
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, needle), "12345");
+}
+
+TEST(StrStrTest, NeedleSmallerThanHaystack) {
+ const char *haystack = "12345";
+ const char *needle = "345";
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, needle), "345");
+}
+
+TEST(StrStrTest, NeedleLargerThanHaystack) {
+ const char *haystack = "123";
+ const char *needle = "12345";
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, needle), nullptr);
+}
+
+TEST(StrStrTest, NeedleAtBeginning) {
+ const char *haystack = "12345";
+ const char *needle = "12";
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, needle), "12345");
+}
+
+TEST(StrStrTest, NeedleInMiddle) {
+ const char *haystack = "abcdefghi";
+ const char *needle = "def";
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, needle), "defghi");
+}
+
+TEST(StrStrTest, NeedleDirectlyBeforeNullTerminator) {
+ const char *haystack = "abcdefghi";
+ const char *needle = "ghi";
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, needle), "ghi");
+}
+
+TEST(StrStrTest, NeedlePastNullTerminator) {
+ const char haystack[5] = {'1', '2', '\0', '3', '4'};
+ // Shouldn't find anything after the null terminator.
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, /*needle=*/"3"), nullptr);
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, /*needle=*/"4"), nullptr);
+}
+
+TEST(StrStrTest, PartialNeedle) {
+ const char *haystack = "la_ap_lap";
+ const char *needle = "lap";
+ // Shouldn't find la or ap.
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, needle), "lap");
+}
+
+TEST(StrStrTest, MisspelledNeedle) {
+ const char *haystack = "atalloftwocities...wait, tale";
+ const char *needle = "tale";
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, needle), "tale");
+}
+
+TEST(StrStrTest, AnagramNeedle) {
+ const char *haystack = "dgo_ogd_god_odg_gdo_dog";
+ const char *needle = "dog";
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, needle), "dog");
+}
+
+TEST(StrStrTest, MorphedNeedle) {
+ // Changes a single letter in the needle to mismatch with the haystack.
+ const char *haystack = "once upon a time";
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, "time"), "time");
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, "lime"), nullptr);
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, "tome"), nullptr);
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, "tire"), nullptr);
+ ASSERT_STREQ(__llvm_libc::strstr(haystack, "timo"), nullptr);
+}
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