From 949f5460fb8ab73512b7f721cee99440fa956e56 Mon Sep 17 00:00:00 2001
From: Timothy Flynn <trflynn89@pm.me>
Date: Thu, 8 Dec 2022 08:08:08 -0500
Subject: [PATCH] AK: Add formatters for Span<T> and Span<T const>

This generalizes the formatter currently used for Vector to be usable
for any Span.
---
 AK/Format.h             | 27 +++++++++++++++++++++++----
 Tests/AK/TestFormat.cpp | 19 +++++++++++++++++++
 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/AK/Format.h b/AK/Format.h
index b493b3c557..48682c2dbe 100644
--- a/AK/Format.h
+++ b/AK/Format.h
@@ -329,15 +329,16 @@ struct Formatter<StringView> : StandardFormatter {
     ErrorOr<void> format(FormatBuilder&, StringView);
 };
 
-template<typename T, size_t inline_capacity>
-requires(HasFormatter<T>) struct Formatter<Vector<T, inline_capacity>> : StandardFormatter {
-
+template<typename T>
+requires(HasFormatter<T>)
+struct Formatter<Span<T const>> : StandardFormatter {
     Formatter() = default;
     explicit Formatter(StandardFormatter formatter)
         : StandardFormatter(move(formatter))
     {
     }
-    ErrorOr<void> format(FormatBuilder& builder, Vector<T> value)
+
+    ErrorOr<void> format(FormatBuilder& builder, Span<T const> value)
     {
         if (m_mode == Mode::Pointer) {
             Formatter<FlatPtr> formatter { *this };
@@ -375,6 +376,24 @@ requires(HasFormatter<T>) struct Formatter<Vector<T, inline_capacity>> : Standar
     }
 };
 
+template<typename T>
+requires(HasFormatter<T>)
+struct Formatter<Span<T>> : Formatter<Span<T const>> {
+    ErrorOr<void> format(FormatBuilder& builder, Span<T> value)
+    {
+        return Formatter<Span<T const>>::format(builder, value);
+    }
+};
+
+template<typename T, size_t inline_capacity>
+requires(HasFormatter<T>)
+struct Formatter<Vector<T, inline_capacity>> : Formatter<Span<T const>> {
+    ErrorOr<void> format(FormatBuilder& builder, Vector<T, inline_capacity> const& value)
+    {
+        return Formatter<Span<T const>>::format(builder, value.span());
+    }
+};
+
 template<>
 struct Formatter<ReadonlyBytes> : Formatter<StringView> {
     ErrorOr<void> format(FormatBuilder& builder, ReadonlyBytes value)
diff --git a/Tests/AK/TestFormat.cpp b/Tests/AK/TestFormat.cpp
index f5245e2d4a..0d45b3b31a 100644
--- a/Tests/AK/TestFormat.cpp
+++ b/Tests/AK/TestFormat.cpp
@@ -316,6 +316,25 @@ TEST_CASE(hex_dump)
     EXPECT_EQ(DeprecatedString::formatted("{:*>4hex-dump}", "0000"), "30303030****0000");
 }
 
+TEST_CASE(span_format)
+{
+    {
+        Vector<int> v { 1, 2, 3, 4 };
+        EXPECT_EQ(DeprecatedString::formatted("{}", v.span()), "[ 1, 2, 3, 4 ]");
+        EXPECT_EQ(DeprecatedString::formatted("{}", const_cast<AddConst<decltype(v)>&>(v).span()), "[ 1, 2, 3, 4 ]");
+    }
+    {
+        Vector<StringView> v { "1"sv, "2"sv, "3"sv, "4"sv };
+        EXPECT_EQ(DeprecatedString::formatted("{}", v.span()), "[ 1, 2, 3, 4 ]");
+        EXPECT_EQ(DeprecatedString::formatted("{}", const_cast<AddConst<decltype(v)>&>(v).span()), "[ 1, 2, 3, 4 ]");
+    }
+    {
+        Vector<Vector<DeprecatedString>> v { { "1"sv, "2"sv }, { "3"sv, "4"sv } };
+        EXPECT_EQ(DeprecatedString::formatted("{}", v.span()), "[ [ 1, 2 ], [ 3, 4 ] ]");
+        EXPECT_EQ(DeprecatedString::formatted("{}", const_cast<AddConst<decltype(v)>&>(v).span()), "[ [ 1, 2 ], [ 3, 4 ] ]");
+    }
+}
+
 TEST_CASE(vector_format)
 {
     {