From 7c33f8f7df321e2406f324f9aaa3890620a192e5 Mon Sep 17 00:00:00 2001
From: demostanis <demostanis@protonmail.com>
Date: Sat, 22 Oct 2022 16:31:59 +0200
Subject: [PATCH] AK: Add SplitBehavior::KeepTrailingSeparator with tests

---
 AK/String.cpp               | 6 ++++--
 AK/StringUtils.h            | 9 ++++++++-
 AK/StringView.cpp           | 3 ++-
 AK/StringView.h             | 9 +++++++--
 Tests/AK/TestStringView.cpp | 5 +++++
 5 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/AK/String.cpp b/AK/String.cpp
index 2497e8c8b42..3c63b70b62a 100644
--- a/AK/String.cpp
+++ b/AK/String.cpp
@@ -110,12 +110,13 @@ Vector<String> String::split_limit(char separator, size_t limit, SplitBehavior s
     Vector<String> v;
     size_t substart = 0;
     bool keep_empty = has_flag(split_behavior, SplitBehavior::KeepEmpty);
+    bool keep_separator = has_flag(split_behavior, SplitBehavior::KeepTrailingSeparator);
     for (size_t i = 0; i < length() && (v.size() + 1) != limit; ++i) {
         char ch = characters()[i];
         if (ch == separator) {
             size_t sublen = i - substart;
             if (sublen != 0 || keep_empty)
-                v.append(substring(substart, sublen));
+                v.append(substring(substart, keep_separator ? sublen + 1 : sublen));
             substart = i + 1;
         }
     }
@@ -133,12 +134,13 @@ Vector<StringView> String::split_view(Function<bool(char)> separator, SplitBehav
     Vector<StringView> v;
     size_t substart = 0;
     bool keep_empty = has_flag(split_behavior, SplitBehavior::KeepEmpty);
+    bool keep_separator = has_flag(split_behavior, SplitBehavior::KeepTrailingSeparator);
     for (size_t i = 0; i < length(); ++i) {
         char ch = characters()[i];
         if (separator(ch)) {
             size_t sublen = i - substart;
             if (sublen != 0 || keep_empty)
-                v.append(substring_view(substart, sublen));
+                v.append(substring_view(substart, keep_separator ? sublen + 1 : sublen));
             substart = i + 1;
         }
     }
diff --git a/AK/StringUtils.h b/AK/StringUtils.h
index 60dde9c359b..883196ecfbe 100644
--- a/AK/StringUtils.h
+++ b/AK/StringUtils.h
@@ -40,10 +40,17 @@ enum class TrimWhitespace {
 };
 
 enum class SplitBehavior : unsigned {
+    // Neither keep empty substrings nor keep the trailing separator.
+    // This is the default behavior if unspecified.
     Nothing = 0,
+
     // If two separators follow each other without any characters
-    // in between, keep a "" in the resulting vector.
+    // in between, keep a "" in the resulting vector. (or only the
+    // separator if KeepTrailingSeparator is used)
     KeepEmpty = 1,
+
+    // Do not strip off the separator at the end of the string.
+    KeepTrailingSeparator = 2,
 };
 AK_ENUM_BITWISE_OPERATORS(SplitBehavior);
 
diff --git a/AK/StringView.cpp b/AK/StringView.cpp
index 1b906d7970f..3840e7c7f5a 100644
--- a/AK/StringView.cpp
+++ b/AK/StringView.cpp
@@ -272,12 +272,13 @@ Vector<StringView> StringView::split_view_if(Function<bool(char)> const& predica
     Vector<StringView> v;
     size_t substart = 0;
     bool keep_empty = has_flag(split_behavior, SplitBehavior::KeepEmpty);
+    bool keep_separator = has_flag(split_behavior, SplitBehavior::KeepTrailingSeparator);
     for (size_t i = 0; i < length(); ++i) {
         char ch = characters_without_null_termination()[i];
         if (predicate(ch)) {
             size_t sublen = i - substart;
             if (sublen != 0 || keep_empty)
-                v.append(substring_view(substart, sublen));
+                v.append(substring_view(substart, keep_separator ? sublen + 1 : sublen));
             substart = i + 1;
         }
     }
diff --git a/AK/StringView.h b/AK/StringView.h
index e9d58c31985..8e65691e5a3 100644
--- a/AK/StringView.h
+++ b/AK/StringView.h
@@ -170,11 +170,16 @@ public:
 
         auto maybe_separator_index = find(separator);
         bool keep_empty = has_flag(split_behavior, SplitBehavior::KeepEmpty);
+        bool keep_separator = has_flag(split_behavior, SplitBehavior::KeepTrailingSeparator);
         while (maybe_separator_index.has_value()) {
             auto separator_index = maybe_separator_index.value();
             auto part_with_separator = view.substring_view(0, separator_index + separator.length());
-            if (keep_empty || separator_index > 0)
-                callback(part_with_separator.substring_view(0, separator_index));
+            if (keep_empty || separator_index > 0) {
+                if (keep_separator)
+                    callback(part_with_separator);
+                else
+                    callback(part_with_separator.substring_view(0, separator_index));
+            }
             view = view.substring_view_starting_after_substring(part_with_separator);
             maybe_separator_index = view.find(separator);
         }
diff --git a/Tests/AK/TestStringView.cpp b/Tests/AK/TestStringView.cpp
index 6aafffe82ba..9d5bc18e0a6 100644
--- a/Tests/AK/TestStringView.cpp
+++ b/Tests/AK/TestStringView.cpp
@@ -163,6 +163,11 @@ TEST_CASE(split_view)
     EXPECT_EQ(test_string_view.split_view_if(predicate, SplitBehavior::KeepEmpty), Vector({ "a"sv, ""sv, "b"sv, "c"sv, "d"sv }));
     EXPECT_EQ(test_string_view.split_view_if(predicate), Vector({ "a"sv, "b"sv, "c"sv, "d"sv }));
     EXPECT_EQ(test_string_view.split_view_if(predicate, SplitBehavior::KeepEmpty), Vector({ "a"sv, ""sv, "b"sv, "c"sv, "d"sv }));
+
+    test_string_view = "a,,,b"sv;
+    EXPECT_EQ(test_string_view.split_view(","sv, SplitBehavior::KeepEmpty), Vector({ "a"sv, ""sv, ""sv, "b"sv }));
+    EXPECT_EQ(test_string_view.split_view(","sv, SplitBehavior::KeepTrailingSeparator), Vector({ "a,"sv, "b"sv }));
+    EXPECT_EQ(test_string_view.split_view(","sv, SplitBehavior::KeepTrailingSeparator | SplitBehavior::KeepEmpty), Vector({ "a,"sv, ","sv, ","sv, "b"sv }));
 }
 
 TEST_CASE(constexpr_stuff)