From 2370efbea6c1b46c1e7aacc303d9a5439c945fcd Mon Sep 17 00:00:00 2001
From: Timothy Flynn <trflynn89@pm.me>
Date: Mon, 12 Apr 2021 07:54:22 -0400
Subject: [PATCH] AK: Add a predicate variant of StringView::split_view

---
 AK/StringView.cpp           |  1 -
 AK/StringView.h             | 24 ++++++++++++++++++++++++
 AK/Tests/TestStringView.cpp |  7 +++++++
 3 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/AK/StringView.cpp b/AK/StringView.cpp
index a08d31ff945..50a4c3b677a 100644
--- a/AK/StringView.cpp
+++ b/AK/StringView.cpp
@@ -31,7 +31,6 @@
 #include <AK/Memory.h>
 #include <AK/String.h>
 #include <AK/StringView.h>
-#include <AK/Vector.h>
 
 namespace AK {
 
diff --git a/AK/StringView.h b/AK/StringView.h
index 3fa71bf85f4..ae8e5a7a47c 100644
--- a/AK/StringView.h
+++ b/AK/StringView.h
@@ -32,6 +32,7 @@
 #include <AK/Span.h>
 #include <AK/StdLibExtras.h>
 #include <AK/StringUtils.h>
+#include <AK/Vector.h>
 
 namespace AK {
 
@@ -108,6 +109,29 @@ public:
     [[nodiscard]] Vector<StringView> split_view(char, bool keep_empty = false) const;
     [[nodiscard]] Vector<StringView> split_view(const StringView&, bool keep_empty = false) const;
 
+    template<typename UnaryPredicate>
+    [[nodiscard]] Vector<StringView> split_view_if(UnaryPredicate&& predicate, bool keep_empty = false) const
+    {
+        if (is_empty())
+            return {};
+
+        Vector<StringView> v;
+        size_t substart = 0;
+        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));
+                substart = i + 1;
+            }
+        }
+        size_t taillen = length() - substart;
+        if (taillen != 0 || keep_empty)
+            v.append(substring_view(substart, taillen));
+        return v;
+    }
+
     // Create a Vector of StringViews split by line endings. As of CommonMark
     // 0.29, the spec defines a line ending as "a newline (U+000A), a carriage
     // return (U+000D) not followed by a newline, or a carriage return and a
diff --git a/AK/Tests/TestStringView.cpp b/AK/Tests/TestStringView.cpp
index a95be835bde..3a690700732 100644
--- a/AK/Tests/TestStringView.cpp
+++ b/AK/Tests/TestStringView.cpp
@@ -183,6 +183,13 @@ TEST_CASE(split_view)
     test_string_view = "axxbcxxdxx";
     EXPECT_EQ(test_string_view.split_view("xx"), Vector<StringView>({ "a", "bc", "d" }));
     EXPECT_EQ(test_string_view.split_view("xx", true), Vector<StringView>({ "a", "bc", "d", "" }));
+
+    test_string_view = "ax_b_cxd";
+    auto predicate = [](char ch) { return ch == 'x' || ch == '_'; };
+    EXPECT_EQ(test_string_view.split_view_if(predicate), Vector<StringView>({ "a", "b", "c", "d" }));
+    EXPECT_EQ(test_string_view.split_view_if(predicate, true), Vector<StringView>({ "a", "", "b", "c", "d" }));
+    EXPECT_EQ(test_string_view.split_view_if(predicate), Vector<StringView>({ "a", "b", "c", "d" }));
+    EXPECT_EQ(test_string_view.split_view_if(predicate, true), Vector<StringView>({ "a", "", "b", "c", "d" }));
 }
 
 TEST_MAIN(StringView)