tools/aapt2/util/Util.cpp - platform/frameworks/base - Git at Google

 /*
  * Copyright (C) 2015 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "util/Util.h"

 #include <algorithm>
 #include <ostream>
 #include <string>
 #include <vector>

 #include "android-base/stringprintf.h"
 #include "androidfw/StringPiece.h"
 #include "build/version.h"

 #include "text/Unicode.h"
 #include "text/Utf8Iterator.h"
 #include "util/BigBuffer.h"
 #include "util/Maybe.h"
 #include "utils/Unicode.h"

 using ::aapt::text::Utf8Iterator;
 using ::android::StringPiece;
 using ::android::StringPiece16;

 namespace aapt {
 namespace util {

 static std::vector<std::string> SplitAndTransform(
     const StringPiece& str, char sep, const std::function<char(char)>& 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);
     }
     start = current + 1;
   } while (current != end);
   return parts;
 }

 std::vector<std::string> Split(const StringPiece& str, char sep) {
   return SplitAndTransform(str, sep, nullptr);
 }

 std::vector<std::string> SplitAndLowercase(const StringPiece& str, char sep) {
   return SplitAndTransform(str, sep, ::tolower);
 }

 bool StartsWith(const StringPiece& str, const StringPiece& prefix) {
   if (str.size() < prefix.size()) {
     return false;
   }
   return str.substr(0, prefix.size()) == prefix;
 }

 bool EndsWith(const StringPiece& str, const StringPiece& suffix) {
   if (str.size() < suffix.size()) {
     return false;
   }
   return str.substr(str.size() - suffix.size(), suffix.size()) == suffix;
 }

 StringPiece TrimLeadingWhitespace(const StringPiece& str) {
   if (str.size() == 0 || str.data() == nullptr) {
     return str;
   }

   const char* start = str.data();
   const char* end = start + str.length();

   while (start != end && isspace(*start)) {
     start++;
   }
   return StringPiece(start, end - start);
 }

 StringPiece TrimTrailingWhitespace(const StringPiece& str) {
   if (str.size() == 0 || str.data() == nullptr) {
     return str;
   }

   const char* start = str.data();
   const char* end = start + str.length();

   while (end != start && isspace(*(end - 1))) {
     end--;
   }
   return StringPiece(start, end - start);
 }

 StringPiece TrimWhitespace(const StringPiece& str) {
   if (str.size() == 0 || str.data() == nullptr) {
     return str;
   }

   const char* start = str.data();
   const char* end = str.data() + str.length();

   while (start != end && isspace(*start)) {
     start++;
   }

   while (end != start && isspace(*(end - 1))) {
     end--;
   }

   return StringPiece(start, end - start);
 }

 static int IsJavaNameImpl(const StringPiece& str) {
   int pieces = 0;
   for (const StringPiece& piece : Tokenize(str, '.')) {
     pieces++;
     if (!text::IsJavaIdentifier(piece)) {
       return -1;
     }
   }
   return pieces;
 }

 bool IsJavaClassName(const StringPiece& str) {
   return IsJavaNameImpl(str) >= 2;
 }

 bool IsJavaPackageName(const StringPiece& str) {
   return IsJavaNameImpl(str) >= 1;
 }

 static int IsAndroidNameImpl(const StringPiece& str) {
   int pieces = 0;
   for (const StringPiece& piece : Tokenize(str, '.')) {
     if (piece.empty()) {
       return -1;
     }

     const char first_character = piece.data()[0];
     if (!::isalpha(first_character)) {
       return -1;
     }

     bool valid = std::all_of(piece.begin() + 1, piece.end(), [](const char c) -> bool {
       return ::isalnum(c) || c == '_';
     });

     if (!valid) {
       return -1;
     }
     pieces++;
   }
   return pieces;
 }

 bool IsAndroidPackageName(const StringPiece& str) {
   return IsAndroidNameImpl(str) > 1 || str == "android";
 }

 bool IsAndroidSplitName(const StringPiece& str) {
   return IsAndroidNameImpl(str) > 0;
 }

 Maybe<std::string> GetFullyQualifiedClassName(const StringPiece& package,
                                               const StringPiece& classname) {
   if (classname.empty()) {
     return {};
   }

   if (util::IsJavaClassName(classname)) {
     return classname.to_string();
   }

   if (package.empty()) {
     return {};
   }

   std::string result = package.to_string();
   if (classname.data()[0] != '.') {
     result += '.';
   }

   result.append(classname.data(), classname.size());
   if (!IsJavaClassName(result)) {
     return {};
   }
   return result;
 }

 const char* GetToolName() {
   static const char* const sToolName = "Android Asset Packaging Tool (aapt)";
   return sToolName;
 }

 std::string GetToolFingerprint() {
   // DO NOT UPDATE, this is more of a marketing version.
   static const char* const sMajorVersion = "2";

   // Update minor version whenever a feature or flag is added.
   static const char* const sMinorVersion = "19";

   // The build id of aapt2 binary.
   static const std::string sBuildId = android::build::GetBuildNumber();

   return android::base::StringPrintf("%s.%s-%s", sMajorVersion, sMinorVersion, sBuildId.c_str());
 }

 static size_t ConsumeDigits(const char* start, const char* end) {
   const char* c = start;
   for (; c != end && *c >= '0' && *c <= '9'; c++) {
   }
   return static_cast<size_t>(c - start);
 }

 bool VerifyJavaStringFormat(const StringPiece& str) {
   const char* c = str.begin();
   const char* const end = str.end();

   size_t arg_count = 0;
   bool nonpositional = false;
   while (c != end) {
     if (*c == '%' && c + 1 < end) {
       c++;

       if (*c == '%' || *c == 'n') {
         c++;
         continue;
       }

       arg_count++;

       size_t num_digits = ConsumeDigits(c, end);
       if (num_digits > 0) {
         c += num_digits;
         if (c != end && *c != '$') {
           // The digits were a size, but not a positional argument.
           nonpositional = true;
         }
       } else if (*c == '<') {
         // Reusing last argument, bad idea since positions can be moved around
         // during translation.
         nonpositional = true;

         c++;

         // Optionally we can have a $ after
         if (c != end && *c == '$') {
           c++;
         }
       } else {
         nonpositional = true;
       }

       // Ignore size, width, flags, etc.
       while (c != end && (*c == '-' || *c == '#' || *c == '+' || *c == ' ' ||
                           *c == ',' || *c == '(' || (*c >= '0' && *c <= '9'))) {
         c++;
       }

       /*
        * This is a shortcut to detect strings that are going to Time.format()
        * instead of String.format()
        *
        * Comparison of String.format() and Time.format() args:
        *
        * String: ABC E GH  ST X abcdefgh  nost x
        *   Time:    DEFGHKMS W Za  d   hkm  s w yz
        *
        * Therefore we know it's definitely Time if we have:
        *     DFKMWZkmwyz
        */
       if (c != end) {
         switch (*c) {
           case 'D':
           case 'F':
           case 'K':
           case 'M':
           case 'W':
           case 'Z':
           case 'k':
           case 'm':
           case 'w':
           case 'y':
           case 'z':
             return true;
         }
       }
     }

     if (c != end) {
       c++;
     }
   }

   if (arg_count > 1 && nonpositional) {
     // Multiple arguments were specified, but some or all were non positional.
     // Translated
     // strings may rearrange the order of the arguments, which will break the
     // string.
     return false;
   }
   return true;
 }

 std::string Utf8ToModifiedUtf8(const std::string& 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
   // codepoints replaced with 2 3 byte surrogate pairs
   size_t modified_size = 0;
   const size_t size = utf8.size();
   for (size_t i = 0; i < size; i++) {
     if (((uint8_t) utf8[i] >> 4) == 0xF) {
       modified_size += 6;
       i += 3;
     } else {
       modified_size++;
     }
   }

   // Early out if no 4 byte codepoints are found
   if (size == modified_size) {
     return utf8;
   }

   std::string output;
   output.reserve(modified_size);
   for (size_t i = 0; i < size; i++) {
     if (((uint8_t) utf8[i] >> 4) == 0xF) {
       int32_t codepoint = utf32_from_utf8_at(utf8.data(), size, i, nullptr);

       // Calculate the high and low surrogates as UTF-16 would
       int32_t high = ((codepoint - 0x10000) / 0x400) + 0xD800;
       int32_t low = ((codepoint - 0x10000) % 0x400) + 0xDC00;

       // Encode each surrogate in UTF-8
       output.push_back((char) (0xE4 | ((high >> 12) & 0xF)));
       output.push_back((char) (0x80 | ((high >> 6) & 0x3F)));
       output.push_back((char) (0x80 | (high & 0x3F)));
       output.push_back((char) (0xE4 | ((low >> 12) & 0xF)));
       output.push_back((char) (0x80 | ((low >> 6) & 0x3F)));
       output.push_back((char) (0x80 | (low & 0x3F)));
       i += 3;
     } else {
       output.push_back(utf8[i]);
     }
   }

   return output;
 }

 std::string ModifiedUtf8ToUtf8(const std::string& modified_utf8) {
   // The UTF-8 representation will have a byte length less than or equal to the Modified UTF-8
   // representation.
   std::string output;
   output.reserve(modified_utf8.size());

   size_t index = 0;
   const size_t modified_size = modified_utf8.size();
   while (index < modified_size) {
     size_t next_index;
     int32_t high_surrogate = utf32_from_utf8_at(modified_utf8.data(), modified_size, index,
                                                 &next_index);
     if (high_surrogate < 0) {
       return {};
     }

     // Check that the first codepoint is within the high surrogate range
     if (high_surrogate >= 0xD800 && high_surrogate <= 0xDB7F) {
       int32_t low_surrogate = utf32_from_utf8_at(modified_utf8.data(), modified_size, next_index,
                                                  &next_index);
       if (low_surrogate < 0) {
         return {};
       }

       // Check that the second codepoint is within the low surrogate range
       if (low_surrogate >= 0xDC00 && low_surrogate <= 0xDFFF) {
         const char32_t codepoint = (char32_t) (((high_surrogate - 0xD800) * 0x400)
             + (low_surrogate - 0xDC00) + 0x10000);

         // The decoded codepoint should represent a 4 byte, UTF-8 character
         const size_t utf8_length = (size_t) utf32_to_utf8_length(&codepoint, 1);
         if (utf8_length != 4) {
           return {};
         }

         // Encode the UTF-8 representation of the codepoint into the string
         char* start = &output[output.size()];
         output.resize(output.size() + utf8_length);
         utf32_to_utf8((char32_t*) &codepoint, 1, start, utf8_length + 1);

         index = next_index;
         continue;
       }
     }

     // Append non-surrogate pairs to the output string
     for (size_t i = index; i < next_index; i++) {
       output.push_back(modified_utf8[i]);
     }
     index = next_index;
   }
   return output;
 }

 std::u16string Utf8ToUtf16(const StringPiece& utf8) {
   ssize_t utf16_length = utf8_to_utf16_length(
       reinterpret_cast<const uint8_t*>(utf8.data()), utf8.length());
   if (utf16_length <= 0) {
     return {};
   }

   std::u16string utf16;
   utf16.resize(utf16_length);
   utf8_to_utf16(reinterpret_cast<const uint8_t*>(utf8.data()), utf8.length(),
                 &*utf16.begin(), utf16_length + 1);
   return utf16;
 }

 std::string Utf16ToUtf8(const StringPiece16& utf16) {
   ssize_t utf8_length = utf16_to_utf8_length(utf16.data(), utf16.length());
   if (utf8_length <= 0) {
     return {};
   }

   std::string utf8;
   utf8.resize(utf8_length);
   utf16_to_utf8(utf16.data(), utf16.length(), &*utf8.begin(), utf8_length + 1);
   return utf8;
 }

 bool WriteAll(std::ostream& out, const BigBuffer& buffer) {
   for (const auto& b : buffer) {
     if (!out.write(reinterpret_cast<const char*>(b.buffer.get()), b.size)) {
       return false;
     }
   }
   return true;
 }

 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()]);
   uint8_t* p = data.get();
   for (const auto& block : buffer) {
     memcpy(p, block.buffer.get(), block.size);
     p += block.size;
   }
   return data;
 }

 typename Tokenizer::iterator& Tokenizer::iterator::operator++() {
   const char* start = token_.end();
   const char* end = str_.end();
   if (start == end) {
     end_ = true;
     token_.assign(token_.end(), 0);
     return *this;
   }

   start += 1;
   const char* current = start;
   while (current != end) {
     if (*current == separator_) {
       token_.assign(start, current - start);
       return *this;
     }
     ++current;
   }
   token_.assign(start, end - start);
   return *this;
 }

 bool Tokenizer::iterator::operator==(const iterator& rhs) const {
   // We check equality here a bit differently.
   // We need to know that the addresses are the same.
   return token_.begin() == rhs.token_.begin() &&
          token_.end() == rhs.token_.end() && end_ == rhs.end_;
 }

 bool Tokenizer::iterator::operator!=(const iterator& rhs) const {
   return !(*this == rhs);
 }

 Tokenizer::iterator::iterator(const StringPiece& s, char sep, const StringPiece& tok, bool end)
     : str_(s), separator_(sep), token_(tok), end_(end) {}

 Tokenizer::Tokenizer(const StringPiece& str, char sep)
     : begin_(++iterator(str, sep, StringPiece(str.begin() - 1, 0), false)),
       end_(str, sep, StringPiece(str.end(), 0), true) {}

 bool ExtractResFilePathParts(const StringPiece& path, StringPiece* out_prefix,
                              StringPiece* out_entry, StringPiece* out_suffix) {
   const StringPiece res_prefix("res/");
   if (!StartsWith(path, res_prefix)) {
     return false;
   }

   StringPiece::const_iterator last_occurence = path.end();
   for (auto iter = path.begin() + res_prefix.size(); iter != path.end();
        ++iter) {
     if (*iter == '/') {
       last_occurence = iter;
     }
   }

   if (last_occurence == path.end()) {
     return false;
   }

   auto iter = std::find(last_occurence, path.end(), '.');
   *out_suffix = StringPiece(iter, path.end() - iter);
   *out_entry = StringPiece(last_occurence + 1, iter - last_occurence - 1);
   *out_prefix = StringPiece(path.begin(), last_occurence - path.begin() + 1);
   return true;
 }

 StringPiece16 GetString16(const android::ResStringPool& pool, size_t idx) {
   size_t len;
   const char16_t* str = pool.stringAt(idx, &len);
   if (str != nullptr) {
     return StringPiece16(str, len);
   }
   return StringPiece16();
 }

 std::string GetString(const android::ResStringPool& pool, size_t idx) {
   size_t len;
   const char* str = pool.string8At(idx, &len);
   if (str != nullptr) {
     return ModifiedUtf8ToUtf8(std::string(str, len));
   }
   return Utf16ToUtf8(GetString16(pool, idx));
 }

 }  // namespace util
 }  // namespace aapt
	/*
	* Copyright (C) 2015 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "util/Util.h"

	#include <algorithm>
	#include <ostream>
	#include <string>
	#include <vector>

	#include "android-base/stringprintf.h"
	#include "androidfw/StringPiece.h"
	#include "build/version.h"

	#include "text/Unicode.h"
	#include "text/Utf8Iterator.h"
	#include "util/BigBuffer.h"
	#include "util/Maybe.h"
	#include "utils/Unicode.h"

	using ::aapt::text::Utf8Iterator;
	using ::android::StringPiece;
	using ::android::StringPiece16;

	namespace aapt {
	namespace util {

	static std::vector<std::string> SplitAndTransform(
	const StringPiece& str, char sep, const std::function<char(char)>& 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);
	}
	start = current + 1;
	} while (current != end);
	return parts;
	}

	std::vector<std::string> Split(const StringPiece& str, char sep) {
	return SplitAndTransform(str, sep, nullptr);
	}

	std::vector<std::string> SplitAndLowercase(const StringPiece& str, char sep) {
	return SplitAndTransform(str, sep, ::tolower);
	}

	bool StartsWith(const StringPiece& str, const StringPiece& prefix) {
	if (str.size() < prefix.size()) {
	return false;
	}
	return str.substr(0, prefix.size()) == prefix;
	}

	bool EndsWith(const StringPiece& str, const StringPiece& suffix) {
	if (str.size() < suffix.size()) {
	return false;
	}
	return str.substr(str.size() - suffix.size(), suffix.size()) == suffix;
	}

	StringPiece TrimLeadingWhitespace(const StringPiece& str) {
	if (str.size() == 0 \|\| str.data() == nullptr) {
	return str;
	}

	const char* start = str.data();
	const char* end = start + str.length();

	while (start != end && isspace(*start)) {
	start++;
	}
	return StringPiece(start, end - start);
	}

	StringPiece TrimTrailingWhitespace(const StringPiece& str) {
	if (str.size() == 0 \|\| str.data() == nullptr) {
	return str;
	}

	const char* start = str.data();
	const char* end = start + str.length();

	while (end != start && isspace(*(end - 1))) {
	end--;
	}
	return StringPiece(start, end - start);
	}

	StringPiece TrimWhitespace(const StringPiece& str) {
	if (str.size() == 0 \|\| str.data() == nullptr) {
	return str;
	}

	const char* start = str.data();
	const char* end = str.data() + str.length();

	while (start != end && isspace(*start)) {
	start++;
	}

	while (end != start && isspace(*(end - 1))) {
	end--;
	}

	return StringPiece(start, end - start);
	}

	static int IsJavaNameImpl(const StringPiece& str) {
	int pieces = 0;
	for (const StringPiece& piece : Tokenize(str, '.')) {
	pieces++;
	if (!text::IsJavaIdentifier(piece)) {
	return -1;
	}
	}
	return pieces;
	}

	bool IsJavaClassName(const StringPiece& str) {
	return IsJavaNameImpl(str) >= 2;
	}

	bool IsJavaPackageName(const StringPiece& str) {
	return IsJavaNameImpl(str) >= 1;
	}

	static int IsAndroidNameImpl(const StringPiece& str) {
	int pieces = 0;
	for (const StringPiece& piece : Tokenize(str, '.')) {
	if (piece.empty()) {
	return -1;
	}

	const char first_character = piece.data()[0];
	if (!::isalpha(first_character)) {
	return -1;
	}

	bool valid = std::all_of(piece.begin() + 1, piece.end(), [](const char c) -> bool {
	return ::isalnum(c) \|\| c == '_';
	});

	if (!valid) {
	return -1;
	}
	pieces++;
	}
	return pieces;
	}

	bool IsAndroidPackageName(const StringPiece& str) {
	return IsAndroidNameImpl(str) > 1 \|\| str == "android";
	}

	bool IsAndroidSplitName(const StringPiece& str) {
	return IsAndroidNameImpl(str) > 0;
	}

	Maybe<std::string> GetFullyQualifiedClassName(const StringPiece& package,
	const StringPiece& classname) {
	if (classname.empty()) {
	return {};
	}

	if (util::IsJavaClassName(classname)) {
	return classname.to_string();
	}

	if (package.empty()) {
	return {};
	}

	std::string result = package.to_string();
	if (classname.data()[0] != '.') {
	result += '.';
	}

	result.append(classname.data(), classname.size());
	if (!IsJavaClassName(result)) {
	return {};
	}
	return result;
	}

	const char* GetToolName() {
	static const char* const sToolName = "Android Asset Packaging Tool (aapt)";
	return sToolName;
	}

	std::string GetToolFingerprint() {
	// DO NOT UPDATE, this is more of a marketing version.
	static const char* const sMajorVersion = "2";

	// Update minor version whenever a feature or flag is added.
	static const char* const sMinorVersion = "19";

	// The build id of aapt2 binary.
	static const std::string sBuildId = android::build::GetBuildNumber();

	return android::base::StringPrintf("%s.%s-%s", sMajorVersion, sMinorVersion, sBuildId.c_str());
	}

	static size_t ConsumeDigits(const char* start, const char* end) {
	const char* c = start;
	for (; c != end && c >= '0' && c <= '9'; c++) {
	}
	return static_cast<size_t>(c - start);
	}

	bool VerifyJavaStringFormat(const StringPiece& str) {
	const char* c = str.begin();
	const char* const end = str.end();

	size_t arg_count = 0;
	bool nonpositional = false;
	while (c != end) {
	if (*c == '%' && c + 1 < end) {
	c++;

	if (c == '%' \|\| c == 'n') {
	c++;
	continue;
	}

	arg_count++;

	size_t num_digits = ConsumeDigits(c, end);
	if (num_digits > 0) {
	c += num_digits;
	if (c != end && *c != '$') {
	// The digits were a size, but not a positional argument.
	nonpositional = true;
	}
	} else if (*c == '<') {
	// Reusing last argument, bad idea since positions can be moved around
	// during translation.
	nonpositional = true;

	c++;

	// Optionally we can have a $ after
	if (c != end && *c == '$') {
	c++;
	}
	} else {
	nonpositional = true;
	}

	// Ignore size, width, flags, etc.
	while (c != end && (c == '-' \|\| c == '#' \|\| c == '+' \|\| c == ' ' \|\|
	c == ',' \|\| c == '(' \|\| (c >= '0' && c <= '9'))) {
	c++;
	}

	/*
	* This is a shortcut to detect strings that are going to Time.format()
	* instead of String.format()
	*
	* Comparison of String.format() and Time.format() args:
	*
	* String: ABC E GH ST X abcdefgh nost x
	* Time: DEFGHKMS W Za d hkm s w yz
	*
	* Therefore we know it's definitely Time if we have:
	* DFKMWZkmwyz
	*/
	if (c != end) {
	switch (*c) {
	case 'D':
	case 'F':
	case 'K':
	case 'M':
	case 'W':
	case 'Z':
	case 'k':
	case 'm':
	case 'w':
	case 'y':
	case 'z':
	return true;
	}
	}
	}

	if (c != end) {
	c++;
	}
	}

	if (arg_count > 1 && nonpositional) {
	// Multiple arguments were specified, but some or all were non positional.
	// Translated
	// strings may rearrange the order of the arguments, which will break the
	// string.
	return false;
	}
	return true;
	}

	std::string Utf8ToModifiedUtf8(const std::string& 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
	// codepoints replaced with 2 3 byte surrogate pairs
	size_t modified_size = 0;
	const size_t size = utf8.size();
	for (size_t i = 0; i < size; i++) {
	if (((uint8_t) utf8[i] >> 4) == 0xF) {
	modified_size += 6;
	i += 3;
	} else {
	modified_size++;
	}
	}

	// Early out if no 4 byte codepoints are found
	if (size == modified_size) {
	return utf8;
	}

	std::string output;
	output.reserve(modified_size);
	for (size_t i = 0; i < size; i++) {
	if (((uint8_t) utf8[i] >> 4) == 0xF) {
	int32_t codepoint = utf32_from_utf8_at(utf8.data(), size, i, nullptr);

	// Calculate the high and low surrogates as UTF-16 would
	int32_t high = ((codepoint - 0x10000) / 0x400) + 0xD800;
	int32_t low = ((codepoint - 0x10000) % 0x400) + 0xDC00;

	// Encode each surrogate in UTF-8
	output.push_back((char) (0xE4 \| ((high >> 12) & 0xF)));
	output.push_back((char) (0x80 \| ((high >> 6) & 0x3F)));
	output.push_back((char) (0x80 \| (high & 0x3F)));
	output.push_back((char) (0xE4 \| ((low >> 12) & 0xF)));
	output.push_back((char) (0x80 \| ((low >> 6) & 0x3F)));
	output.push_back((char) (0x80 \| (low & 0x3F)));
	i += 3;
	} else {
	output.push_back(utf8[i]);
	}
	}

	return output;
	}

	std::string ModifiedUtf8ToUtf8(const std::string& modified_utf8) {
	// The UTF-8 representation will have a byte length less than or equal to the Modified UTF-8
	// representation.
	std::string output;
	output.reserve(modified_utf8.size());

	size_t index = 0;
	const size_t modified_size = modified_utf8.size();
	while (index < modified_size) {
	size_t next_index;
	int32_t high_surrogate = utf32_from_utf8_at(modified_utf8.data(), modified_size, index,
	&next_index);
	if (high_surrogate < 0) {
	return {};
	}

	// Check that the first codepoint is within the high surrogate range
	if (high_surrogate >= 0xD800 && high_surrogate <= 0xDB7F) {
	int32_t low_surrogate = utf32_from_utf8_at(modified_utf8.data(), modified_size, next_index,
	&next_index);
	if (low_surrogate < 0) {
	return {};
	}

	// Check that the second codepoint is within the low surrogate range
	if (low_surrogate >= 0xDC00 && low_surrogate <= 0xDFFF) {
	const char32_t codepoint = (char32_t) (((high_surrogate - 0xD800) * 0x400)
	+ (low_surrogate - 0xDC00) + 0x10000);

	// The decoded codepoint should represent a 4 byte, UTF-8 character
	const size_t utf8_length = (size_t) utf32_to_utf8_length(&codepoint, 1);
	if (utf8_length != 4) {
	return {};
	}

	// Encode the UTF-8 representation of the codepoint into the string
	char* start = &output[output.size()];
	output.resize(output.size() + utf8_length);
	utf32_to_utf8((char32_t*) &codepoint, 1, start, utf8_length + 1);

	index = next_index;
	continue;
	}
	}

	// Append non-surrogate pairs to the output string
	for (size_t i = index; i < next_index; i++) {
	output.push_back(modified_utf8[i]);
	}
	index = next_index;
	}
	return output;
	}

	std::u16string Utf8ToUtf16(const StringPiece& utf8) {
	ssize_t utf16_length = utf8_to_utf16_length(
	reinterpret_cast<const uint8_t*>(utf8.data()), utf8.length());
	if (utf16_length <= 0) {
	return {};
	}

	std::u16string utf16;
	utf16.resize(utf16_length);
	utf8_to_utf16(reinterpret_cast<const uint8_t*>(utf8.data()), utf8.length(),
	&*utf16.begin(), utf16_length + 1);
	return utf16;
	}

	std::string Utf16ToUtf8(const StringPiece16& utf16) {
	ssize_t utf8_length = utf16_to_utf8_length(utf16.data(), utf16.length());
	if (utf8_length <= 0) {
	return {};
	}

	std::string utf8;
	utf8.resize(utf8_length);
	utf16_to_utf8(utf16.data(), utf16.length(), &*utf8.begin(), utf8_length + 1);
	return utf8;
	}

	bool WriteAll(std::ostream& out, const BigBuffer& buffer) {
	for (const auto& b : buffer) {
	if (!out.write(reinterpret_cast<const char*>(b.buffer.get()), b.size)) {
	return false;
	}
	}
	return true;
	}

	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()]);
	uint8_t* p = data.get();
	for (const auto& block : buffer) {
	memcpy(p, block.buffer.get(), block.size);
	p += block.size;
	}
	return data;
	}

	typename Tokenizer::iterator& Tokenizer::iterator::operator++() {
	const char* start = token_.end();
	const char* end = str_.end();
	if (start == end) {
	end_ = true;
	token_.assign(token_.end(), 0);
	return *this;
	}

	start += 1;
	const char* current = start;
	while (current != end) {
	if (*current == separator_) {
	token_.assign(start, current - start);
	return *this;
	}
	++current;
	}
	token_.assign(start, end - start);
	return *this;
	}

	bool Tokenizer::iterator::operator==(const iterator& rhs) const {
	// We check equality here a bit differently.
	// We need to know that the addresses are the same.
	return token_.begin() == rhs.token_.begin() &&
	token_.end() == rhs.token_.end() && end_ == rhs.end_;
	}

	bool Tokenizer::iterator::operator!=(const iterator& rhs) const {
	return !(*this == rhs);
	}

	Tokenizer::iterator::iterator(const StringPiece& s, char sep, const StringPiece& tok, bool end)
	: str_(s), separator_(sep), token_(tok), end_(end) {}

	Tokenizer::Tokenizer(const StringPiece& str, char sep)
	: begin_(++iterator(str, sep, StringPiece(str.begin() - 1, 0), false)),
	end_(str, sep, StringPiece(str.end(), 0), true) {}

	bool ExtractResFilePathParts(const StringPiece& path, StringPiece* out_prefix,
	StringPiece* out_entry, StringPiece* out_suffix) {
	const StringPiece res_prefix("res/");
	if (!StartsWith(path, res_prefix)) {
	return false;
	}

	StringPiece::const_iterator last_occurence = path.end();
	for (auto iter = path.begin() + res_prefix.size(); iter != path.end();
	++iter) {
	if (*iter == '/') {
	last_occurence = iter;
	}
	}

	if (last_occurence == path.end()) {
	return false;
	}

	auto iter = std::find(last_occurence, path.end(), '.');
	*out_suffix = StringPiece(iter, path.end() - iter);
	*out_entry = StringPiece(last_occurence + 1, iter - last_occurence - 1);
	*out_prefix = StringPiece(path.begin(), last_occurence - path.begin() + 1);
	return true;
	}

	StringPiece16 GetString16(const android::ResStringPool& pool, size_t idx) {
	size_t len;
	const char16_t* str = pool.stringAt(idx, &len);
	if (str != nullptr) {
	return StringPiece16(str, len);
	}
	return StringPiece16();
	}

	std::string GetString(const android::ResStringPool& pool, size_t idx) {
	size_t len;
	const char* str = pool.string8At(idx, &len);
	if (str != nullptr) {
	return ModifiedUtf8ToUtf8(std::string(str, len));
	}
	return Utf16ToUtf8(GetString16(pool, idx));
	}

	} // namespace util
	} // namespace aapt