From a577514789fc241abe15f793a66f19d6431f7769 Mon Sep 17 00:00:00 2001
From: Yurii Zubrytskyi <zyy@google.com>
Date: Wed, 2 Nov 2022 17:49:49 -0700
Subject: Make StringPiece to be std::string_view alias

Bug: 237583012
Test: build + boot + UTs

Change-Id: I849831f4466d3b9c7ec842b75256e7fcba77a0c0
---
 libs/androidfw/Util.cpp | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

(limited to 'libs/androidfw/Util.cpp')

diff --git a/libs/androidfw/Util.cpp b/libs/androidfw/Util.cpp
index 52ad0dce8187..be55fe8b4bb6 100644
--- a/libs/androidfw/Util.cpp
+++ b/libs/androidfw/Util.cpp
@@ -42,7 +42,7 @@ void ReadUtf16StringFromDevice(const uint16_t* src, size_t len, std::string* out
   }
 }
 
-std::u16string Utf8ToUtf16(const StringPiece& utf8) {
+std::u16string Utf8ToUtf16(StringPiece utf8) {
   ssize_t utf16_length =
       utf8_to_utf16_length(reinterpret_cast<const uint8_t*>(utf8.data()), utf8.length());
   if (utf16_length <= 0) {
@@ -56,7 +56,7 @@ std::u16string Utf8ToUtf16(const StringPiece& utf8) {
   return utf16;
 }
 
-std::string Utf16ToUtf8(const StringPiece16& utf16) {
+std::string Utf16ToUtf8(StringPiece16 utf16) {
   ssize_t utf8_length = utf16_to_utf8_length(utf16.data(), utf16.length());
   if (utf8_length <= 0) {
     return {};
@@ -68,7 +68,7 @@ std::string Utf16ToUtf8(const StringPiece16& utf16) {
   return utf8;
 }
 
-std::string Utf8ToModifiedUtf8(const std::string& utf8) {
+std::string Utf8ToModifiedUtf8(std::string_view utf8) {
   // Java uses Modified UTF-8 which only supports the 1, 2, and 3 byte formats of UTF-8. To encode
   // 4 byte UTF-8 codepoints, Modified UTF-8 allows the use of surrogate pairs in the same format
   // of CESU-8 surrogate pairs. Calculate the size of the utf8 string with all 4 byte UTF-8
@@ -86,7 +86,7 @@ std::string Utf8ToModifiedUtf8(const std::string& utf8) {
 
   // Early out if no 4 byte codepoints are found
   if (size == modified_size) {
-    return utf8;
+    return std::string(utf8);
   }
 
   std::string output;
@@ -115,7 +115,7 @@ std::string Utf8ToModifiedUtf8(const std::string& utf8) {
   return output;
 }
 
-std::string ModifiedUtf8ToUtf8(const std::string& modified_utf8) {
+std::string ModifiedUtf8ToUtf8(std::string_view modified_utf8) {
   // The UTF-8 representation will have a byte length less than or equal to the Modified UTF-8
   // representation.
   std::string output;
@@ -170,30 +170,28 @@ std::string ModifiedUtf8ToUtf8(const std::string& modified_utf8) {
   return output;
 }
 
-static std::vector<std::string> SplitAndTransform(
-    const StringPiece& str, char sep, const std::function<char(char)>& f) {
+template <class Func>
+static std::vector<std::string> SplitAndTransform(StringPiece str, char sep, Func&& f) {
   std::vector<std::string> parts;
   const StringPiece::const_iterator end = std::end(str);
   StringPiece::const_iterator start = std::begin(str);
   StringPiece::const_iterator current;
   do {
     current = std::find(start, end, sep);
-    parts.emplace_back(str.substr(start, current).to_string());
-    if (f) {
-      std::string& part = parts.back();
-      std::transform(part.begin(), part.end(), part.begin(), f);
-    }
+    parts.emplace_back(StringPiece(start, current - start));
+    std::string& part = parts.back();
+    std::transform(part.begin(), part.end(), part.begin(), f);
     start = current + 1;
   } while (current != end);
   return parts;
 }
 
-std::vector<std::string> SplitAndLowercase(const StringPiece& str, char sep) {
-  return SplitAndTransform(str, sep, ::tolower);
+std::vector<std::string> SplitAndLowercase(StringPiece str, char sep) {
+  return SplitAndTransform(str, sep, [](char c) { return ::tolower(c); });
 }
 
 std::unique_ptr<uint8_t[]> Copy(const BigBuffer& buffer) {
-  std::unique_ptr<uint8_t[]> data = std::unique_ptr<uint8_t[]>(new uint8_t[buffer.size()]);
+  auto data = std::unique_ptr<uint8_t[]>(new uint8_t[buffer.size()]);
   uint8_t* p = data.get();
   for (const auto& block : buffer) {
     memcpy(p, block.buffer.get(), block.size);
@@ -211,7 +209,7 @@ StringPiece16 GetString16(const android::ResStringPool& pool, size_t idx) {
 
 std::string GetString(const android::ResStringPool& pool, size_t idx) {
   if (auto str = pool.string8At(idx); str.ok()) {
-    return ModifiedUtf8ToUtf8(str->to_string());
+    return ModifiedUtf8ToUtf8(*str);
   }
   return Utf16ToUtf8(GetString16(pool, idx));
 }
-- 
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