From c59268d15b4c04449a649909f75a24202eb9d8d2 Mon Sep 17 00:00:00 2001
From: Timothy Flynn <trflynn89@pm.me>
Date: Fri, 27 Jan 2023 14:37:40 -0500
Subject: [PATCH] AK: Add String::trim

---
 AK/String.cpp           |  11 ++++
 AK/String.h             |   3 ++
 Tests/AK/TestString.cpp | 112 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 126 insertions(+)

diff --git a/AK/String.cpp b/AK/String.cpp
index e165bf697ab..49aed1d2478 100644
--- a/AK/String.cpp
+++ b/AK/String.cpp
@@ -438,6 +438,17 @@ ErrorOr<String> String::reverse() const
     return builder.to_string();
 }
 
+ErrorOr<String> String::trim(Utf8View const& code_points_to_trim, TrimMode mode) const
+{
+    auto trimmed = code_points().trim(code_points_to_trim, mode);
+    return String::from_utf8(trimmed.as_string());
+}
+
+ErrorOr<String> String::trim(StringView code_points_to_trim, TrimMode mode) const
+{
+    return trim(Utf8View { code_points_to_trim }, mode);
+}
+
 bool String::contains(StringView needle, CaseSensitivity case_sensitivity) const
 {
     return StringUtils::contains(bytes_as_string_view(), needle, case_sensitivity);
diff --git a/AK/String.h b/AK/String.h
index 46821e34261..38873c614cf 100644
--- a/AK/String.h
+++ b/AK/String.h
@@ -130,6 +130,9 @@ public:
     ErrorOr<String> replace(StringView needle, StringView replacement, ReplaceMode replace_mode) const;
     ErrorOr<String> reverse() const;
 
+    ErrorOr<String> trim(Utf8View const& code_points_to_trim, TrimMode mode = TrimMode::Both) const;
+    ErrorOr<String> trim(StringView code_points_to_trim, TrimMode mode = TrimMode::Both) const;
+
     ErrorOr<Vector<String>> split_limit(u32 separator, size_t limit, SplitBehavior = SplitBehavior::Nothing) const;
     ErrorOr<Vector<String>> split(u32 separator, SplitBehavior = SplitBehavior::Nothing) const;
 
diff --git a/Tests/AK/TestString.cpp b/Tests/AK/TestString.cpp
index 4f5d87dee09..38799ddb61a 100644
--- a/Tests/AK/TestString.cpp
+++ b/Tests/AK/TestString.cpp
@@ -495,3 +495,115 @@ TEST_CASE(join)
     auto string7 = MUST(String::join(" - "sv, Array { 1, 16, 256, 4096 }, "[{:#04x}]"sv));
     EXPECT_EQ(string7, "[0x0001] - [0x0010] - [0x0100] - [0x1000]"sv);
 }
+
+TEST_CASE(trim)
+{
+    {
+        String string {};
+
+        auto result = MUST(string.trim(" "sv, TrimMode::Both));
+        EXPECT(result.is_empty());
+
+        result = MUST(string.trim(" "sv, TrimMode::Left));
+        EXPECT(result.is_empty());
+
+        result = MUST(string.trim(" "sv, TrimMode::Right));
+        EXPECT(result.is_empty());
+    }
+    {
+        auto string = MUST(String::from_utf8("word"sv));
+
+        auto result = MUST(string.trim(" "sv, TrimMode::Both));
+        EXPECT_EQ(result, "word"sv);
+
+        result = MUST(string.trim(" "sv, TrimMode::Left));
+        EXPECT_EQ(result, "word"sv);
+
+        result = MUST(string.trim(" "sv, TrimMode::Right));
+        EXPECT_EQ(result, "word"sv);
+    }
+    {
+        auto string = MUST(String::from_utf8("    word"sv));
+
+        auto result = MUST(string.trim(" "sv, TrimMode::Both));
+        EXPECT_EQ(result, "word"sv);
+
+        result = MUST(string.trim(" "sv, TrimMode::Left));
+        EXPECT_EQ(result, "word"sv);
+
+        result = MUST(string.trim(" "sv, TrimMode::Right));
+        EXPECT_EQ(result, "    word"sv);
+    }
+    {
+        auto string = MUST(String::from_utf8("word    "sv));
+
+        auto result = MUST(string.trim(" "sv, TrimMode::Both));
+        EXPECT_EQ(result, "word"sv);
+
+        result = MUST(string.trim(" "sv, TrimMode::Left));
+        EXPECT_EQ(result, "word    "sv);
+
+        result = MUST(string.trim(" "sv, TrimMode::Right));
+        EXPECT_EQ(result, "word"sv);
+    }
+    {
+        auto string = MUST(String::from_utf8("    word    "sv));
+
+        auto result = MUST(string.trim(" "sv, TrimMode::Both));
+        EXPECT_EQ(result, "word"sv);
+
+        result = MUST(string.trim(" "sv, TrimMode::Left));
+        EXPECT_EQ(result, "word    "sv);
+
+        result = MUST(string.trim(" "sv, TrimMode::Right));
+        EXPECT_EQ(result, "    word"sv);
+    }
+    {
+        auto string = MUST(String::from_utf8("    word    "sv));
+
+        auto result = MUST(string.trim("\t"sv, TrimMode::Both));
+        EXPECT_EQ(result, "    word    "sv);
+
+        result = MUST(string.trim("\t"sv, TrimMode::Left));
+        EXPECT_EQ(result, "    word    "sv);
+
+        result = MUST(string.trim("\t"sv, TrimMode::Right));
+        EXPECT_EQ(result, "    word    "sv);
+    }
+    {
+        auto string = MUST(String::from_utf8("ωΣωΣω"sv));
+
+        auto result = MUST(string.trim("ω"sv, TrimMode::Both));
+        EXPECT_EQ(result, "ΣωΣ"sv);
+
+        result = MUST(string.trim("ω"sv, TrimMode::Left));
+        EXPECT_EQ(result, "ΣωΣω"sv);
+
+        result = MUST(string.trim("ω"sv, TrimMode::Right));
+        EXPECT_EQ(result, "ωΣωΣ"sv);
+    }
+    {
+        auto string = MUST(String::from_utf8("ωΣωΣω"sv));
+
+        auto result = MUST(string.trim("ωΣ"sv, TrimMode::Both));
+        EXPECT(result.is_empty());
+
+        result = MUST(string.trim("ωΣ"sv, TrimMode::Left));
+        EXPECT(result.is_empty());
+
+        result = MUST(string.trim("ωΣ"sv, TrimMode::Right));
+        EXPECT(result.is_empty());
+    }
+    {
+        auto string = MUST(String::from_utf8("ωΣωΣω"sv));
+
+        auto result = MUST(string.trim("Σω"sv, TrimMode::Both));
+        EXPECT(result.is_empty());
+
+        result = MUST(string.trim("Σω"sv, TrimMode::Left));
+        EXPECT(result.is_empty());
+
+        result = MUST(string.trim("Σω"sv, TrimMode::Right));
+        EXPECT(result.is_empty());
+    }
+}