More usage of abseil packages. Especially for string util usages. (#2734)

- Faced link errors stemmed from mismatch of api definitions of absl::node_hash_set. So explicitly mentioned this lib as dependency during linking. This is common case/solution for absl hash set lib's link errors as per community.
- Decided to continued to have wrapper (stringutil), so that in future it's easy if we decided to change implementation; client code is safe. Changed most of the implementations & data structures in stringutil, to use abseil stuffs more.
- Though absl::string_view is suitable for most cases where we want immutable/read-only string structures, limiting to stringutil apis, not changing public API signatures (even though no compliance issue); reason: reduce dependency on abseil libs.
- Abseil specific changes done:
    - std::set => absl::node_hash_set
    - std::map => absl::node_hash_map
    - Using absl alternatives for “SplitStringUsing” API and “StringHolder” class impl.
    - Replaced manual impl of prefix and suffix checks with absl::StartsWith() and absl::EndsWith.
    - Similarly used absl::StrReplaceAll, absl::StrCat, absl::StrAppend where possible; and for type conversion apis.
- Note: Tried applying parameter packs to replace manually written duplicate ```StrCat``` apis (for accommodating more number of parameters of same type), but it did not go well when different type arguments passed. Eg char, int types to be converted to StringHolder; faced constructor implicit conversion issues.

cpp/CMakeLists.txt

@@ -570,7 +570,7 @@ if (NOT WIN32)
   list (APPEND TEST_LIBS pthread)
 endif ()
 
-target_link_libraries (libphonenumber_test ${TEST_LIBS})
+target_link_libraries (libphonenumber_test ${TEST_LIBS} absl::node_hash_set)
 
 # Unfortunately add_custom_target() can't accept a single command provided as a
 # list of commands.
@@ -677,7 +677,7 @@ if (${BUILD_GEOCODER} STREQUAL "ON")
     geocoding_test_program
     "test/phonenumbers/geocoding/geocoding_test_program.cc"
   )
-  target_link_libraries (geocoding_test_program geocoding phonenumber)
+  target_link_libraries (geocoding_test_program geocoding phonenumber absl::node_hash_set)
 endif ()
 
 # Build an RPM

cpp/src/phonenumbers/asyoutypeformatter.cc

@@ -29,8 +29,6 @@
 #include "phonenumbers/stringutil.h"
 #include "phonenumbers/unicodestring.h"
 
-#include "absl/strings/str_cat.h"
-#include "absl/strings/str_replace.h"
 
 namespace i18n {
 namespace phonenumbers {
@@ -276,7 +274,7 @@ void AsYouTypeFormatter::GetFormattingTemplate(
   regexp_cache_.GetRegExp(number_pattern).GlobalReplace(
       &a_phone_number, number_format);
   // Replaces each digit with character kDigitPlaceholder.
-  absl::StrReplaceAll({{"9", kDigitPlaceholder}}, &a_phone_number);
+  GlobalReplaceSubstring("9", kDigitPlaceholder, &a_phone_number);
   formatting_template->setTo(a_phone_number.c_str(), a_phone_number.size());
 }
 

cpp/src/phonenumbers/phonenumbermatcher.cc

@@ -756,7 +756,7 @@ void PhoneNumberMatcher::GetNationalNumberGroups(
   size_t start_index = rfc3966_format.find('-') + 1;
   SplitStringUsing(rfc3966_format.substr(start_index,
                                          end_index - start_index),
-                   "-", digit_blocks);
+                   '-', digit_blocks);
 }
 
 void PhoneNumberMatcher::GetNationalNumberGroupsForPattern(
@@ -772,7 +772,7 @@ void PhoneNumberMatcher::GetNationalNumberGroupsForPattern(
                                     *formatting_pattern,
                                     PhoneNumberUtil::RFC3966,
                                     &rfc3966_format);
-  SplitStringUsing(rfc3966_format, "-", digit_blocks);
+  SplitStringUsing(rfc3966_format, '-', digit_blocks);
 }
 
 bool PhoneNumberMatcher::IsNationalPrefixPresentIfRequired(

cpp/src/phonenumbers/phonenumberutil.cc

@@ -47,8 +47,6 @@
 #include "phonenumbers/utf/unicodetext.h"
 #include "phonenumbers/utf/utf.h"
 
-#include "absl/strings/str_replace.h"
-
 namespace i18n {
 namespace phonenumbers {
 
@@ -830,10 +828,10 @@ PhoneNumberUtil::PhoneNumberUtil()
       reg_exps_(new PhoneNumberRegExpsAndMappings),
       country_calling_code_to_region_code_map_(
           new std::vector<IntRegionsPair>()),
-      nanpa_regions_(new std::set<string>()),
-      region_to_metadata_map_(new std::map<string, PhoneMetadata>()),
+      nanpa_regions_(new absl::node_hash_set<string>()),
+      region_to_metadata_map_(new absl::node_hash_map<string, PhoneMetadata>()),
       country_code_to_non_geographical_metadata_map_(
-          new std::map<int, PhoneMetadata>) {
+          new absl::node_hash_map<int, PhoneMetadata>) {
   Logger::set_logger_impl(logger_.get());
   // TODO: Update the java version to put the contents of the init
   // method inside the constructor as well to keep both in sync.
@@ -896,9 +894,10 @@ PhoneNumberUtil::~PhoneNumberUtil() {
       country_calling_code_to_region_code_map_->end());
 }
 
-void PhoneNumberUtil::GetSupportedRegions(std::set<string>* regions) const {
+void PhoneNumberUtil::GetSupportedRegions(std::set<string>* regions)
+    const {
   DCHECK(regions);
-  for (std::map<string, PhoneMetadata>::const_iterator it =
+  for (absl::node_hash_map<string, PhoneMetadata>::const_iterator it =
        region_to_metadata_map_->begin(); it != region_to_metadata_map_->end();
        ++it) {
     regions->insert(it->first);
@@ -908,7 +907,7 @@ void PhoneNumberUtil::GetSupportedRegions(std::set<string>* regions) const {
 void PhoneNumberUtil::GetSupportedGlobalNetworkCallingCodes(
     std::set<int>* calling_codes) const {
   DCHECK(calling_codes);
-  for (std::map<int, PhoneMetadata>::const_iterator it =
+  for (absl::node_hash_map<int, PhoneMetadata>::const_iterator it =
            country_code_to_non_geographical_metadata_map_->begin();
        it != country_code_to_non_geographical_metadata_map_->end(); ++it) {
     calling_codes->insert(it->first);
@@ -1065,7 +1064,7 @@ bool PhoneNumberUtil::HasValidCountryCallingCode(
 // if the region code is invalid or unknown.
 const PhoneMetadata* PhoneNumberUtil::GetMetadataForRegion(
     const string& region_code) const {
-  std::map<string, PhoneMetadata>::const_iterator it =
+  absl::node_hash_map<string, PhoneMetadata>::const_iterator it =
       region_to_metadata_map_->find(region_code);
   if (it != region_to_metadata_map_->end()) {
     return &it->second;
@@ -1075,7 +1074,7 @@ const PhoneMetadata* PhoneNumberUtil::GetMetadataForRegion(
 
 const PhoneMetadata* PhoneNumberUtil::GetMetadataForNonGeographicalRegion(
     int country_calling_code) const {
-  std::map<int, PhoneMetadata>::const_iterator it =
+  absl::node_hash_map<int, PhoneMetadata>::const_iterator it =
       country_code_to_non_geographical_metadata_map_->find(
           country_calling_code);
   if (it != country_code_to_non_geographical_metadata_map_->end()) {
@@ -1175,9 +1174,9 @@ void PhoneNumberUtil::FormatByPattern(
       const string& national_prefix = metadata->national_prefix();
       if (!national_prefix.empty()) {
         // Replace $NP with national prefix and $FG with the first group ($1).
-        absl::StrReplaceAll({{"$NP", national_prefix}},
+        GlobalReplaceSubstring("$NP", national_prefix,
                             &national_prefix_formatting_rule);
-        absl::StrReplaceAll({{"$FG", "$1"}}, &national_prefix_formatting_rule);
+        GlobalReplaceSubstring("$FG", "$1", &national_prefix_formatting_rule);
         num_format_copy.set_national_prefix_formatting_rule(
             national_prefix_formatting_rule);
       } else {
@@ -2026,9 +2025,8 @@ bool PhoneNumberUtil::GetExampleNumberForType(
   DCHECK(number);
   std::set<string> regions;
   GetSupportedRegions(&regions);
-  for (std::set<string>::const_iterator it = regions.begin();
-       it != regions.end(); ++it) {
-    if (GetExampleNumberForType(*it, type, number)) {
+  for (const string& region_code : regions) {
+    if (GetExampleNumberForType(region_code, type, number)) {
       return true;
     }
   }

cpp/src/phonenumbers/phonenumberutil.h

@@ -30,6 +30,9 @@
 #include "phonenumbers/base/memory/singleton.h"
 #include "phonenumbers/phonenumber.pb.h"
 
+#include "absl/container/node_hash_set.h"
+#include "absl/container/node_hash_map.h"
+
 class TelephoneNumber;
 
 namespace i18n {
@@ -805,17 +808,17 @@ class PhoneNumberUtil : public Singleton<PhoneNumberUtil> {
       country_calling_code_to_region_code_map_;
 
   // The set of regions that share country calling code 1.
-  scoped_ptr<std::set<string> > nanpa_regions_;
+  scoped_ptr<absl::node_hash_set<string> > nanpa_regions_;
   static const int kNanpaCountryCode = 1;
 
   // A mapping from a region code to a PhoneMetadata for that region.
-  scoped_ptr<std::map<string, PhoneMetadata> > region_to_metadata_map_;
+  scoped_ptr<absl::node_hash_map<string, PhoneMetadata> > region_to_metadata_map_;
 
   // A mapping from a country calling code for a non-geographical entity to the
   // PhoneMetadata for that country calling code. Examples of the country
   // calling codes include 800 (International Toll Free Service) and 808
   // (International Shared Cost Service).
-  scoped_ptr<std::map<int, PhoneMetadata> >
+  scoped_ptr<absl::node_hash_map<int, PhoneMetadata> >
       country_code_to_non_geographical_metadata_map_;
 
   PhoneNumberUtil();

cpp/src/phonenumbers/regexp_adapter_re2.cc

@@ -27,7 +27,6 @@
 #include "phonenumbers/base/logging.h"
 #include "phonenumbers/stringutil.h"
 
-#include "absl/strings/str_replace.h"
 #include "absl/strings/string_view.h"
 namespace i18n {
 namespace phonenumbers {
@@ -78,14 +77,14 @@ bool DispatchRE2Call(Function regex_function,
 // when they escape dollar-signs.
 string TransformRegularExpressionToRE2Syntax(const string& regex) {
   string re2_regex(regex);
-  if (absl::StrReplaceAll({{"$", "\\"}}, &re2_regex) == 0) {
+  if (GlobalReplaceSubstring("$", "\\", &re2_regex) == 0) {
     return regex;
   }
   // If we replaced a dollar sign with a backslash and there are now two
   // backslashes in the string, we assume that the dollar-sign was previously
   // escaped and that we need to retain it. To do this, we replace pairs of
   // backslashes with a dollar sign.
-  absl::StrReplaceAll({{"\\\\", "$"}}, &re2_regex);
+  GlobalReplaceSubstring("\\\\", "$", &re2_regex);
   return re2_regex;
 }
 

cpp/src/phonenumbers/stringutil.cc

@@ -21,8 +21,9 @@
 
 #include "phonenumbers/stringutil.h"
 
-#include "absl/strings/str_cat.h"
-
+#include "absl/strings/str_replace.h"
+#include "absl/strings/substitute.h"
+#include "absl/strings/match.h"
 
 namespace i18n {
 namespace phonenumbers {
@@ -49,8 +50,7 @@ string SimpleItoa(int64 n) {
 }
 
 bool HasPrefixString(const string& s, const string& prefix) {
-  return s.size() >= prefix.size() &&
-      equal(s.begin(), s.begin() + prefix.size(), prefix.begin());
+  return absl::StartsWith(s, prefix);
 }
 
 size_t FindNth(const string& s, char c, int n) {
@@ -65,33 +65,12 @@ size_t FindNth(const string& s, char c, int n) {
   return pos;
 }
 
-void SplitStringUsing(const string& s, const string& delimiter,
+void SplitStringUsing(const string& s, char delimiter,
                       vector<string>* result) {
   assert(result);
-  size_t start_pos = 0;
-  size_t find_pos = string::npos;
-  if (delimiter.empty()) {
-    return;
-  }
-  while ((find_pos = s.find(delimiter, start_pos)) != string::npos) {
-    const string substring = s.substr(start_pos, find_pos - start_pos);
-    if (!substring.empty()) {
-      result->push_back(substring);
-    }
-    start_pos = find_pos + delimiter.length();
-  }
-  if (start_pos != s.length()) {
-    result->push_back(s.substr(start_pos));
-  }
-}
-
-void StripString(string* s, const char* remove, char replacewith) {
-  const char* str_start = s->c_str();
-  const char* str = str_start;
-  for (str = strpbrk(str, remove);
-       str != NULL;
-       str = strpbrk(str + 1, remove)) {
-    (*s)[str - str_start] = replacewith;
+  for (absl::string_view split_piece : absl::StrSplit(
+           s, absl::ByChar(delimiter), absl::SkipEmpty())) {
+    result->push_back(std::string(split_piece));
   }
 }
 
@@ -104,17 +83,12 @@ bool TryStripPrefixString(const string& in, const string& prefix, string* out) {
 }
 
 bool HasSuffixString(const string& s, const string& suffix) {
-  if (s.length() < suffix.length()) {
-    return false;
-  }
-  return s.compare(s.length() - suffix.length(), suffix.length(), suffix) == 0;
+  return absl::EndsWith(s, suffix);
 }
 
 template <typename T>
 void GenericAtoi(const string& s, T* out) {
-  stringstream stream;
-  stream << s;
-  stream >> *out;
+  absl::SimpleAtoi(s, out);
 }
 
 void safe_strto32(const string& s, int32 *n) {
@@ -143,47 +117,20 @@ void strrmm(string* s, const string& chars) {
 int GlobalReplaceSubstring(const string& substring,
                            const string& replacement,
                            string* s) {
-  assert(s != NULL);
-  if (s->empty() || substring.empty())
-    return 0;
-  string tmp;
-  int num_replacements = 0;
-  int pos = 0;
-  for (size_t match_pos = s->find(substring.data(), pos, substring.length());
-       match_pos != string::npos;
-       pos = static_cast<int>(match_pos + substring.length()),
-          match_pos = s->find(substring.data(), pos, substring.length())) {
-    ++num_replacements;
-    // Append the original content before the match.
-    tmp.append(*s, pos, match_pos - pos);
-    // Append the replacement for the match.
-    tmp.append(replacement.begin(), replacement.end());
-  }
-  // Append the content after the last match.
-  tmp.append(*s, pos, s->length() - pos);
-  s->swap(tmp);
-  return num_replacements;
+  return absl::StrReplaceAll({{substring, replacement}}, s);;
 }
 
 // StringHolder class
-
 StringHolder::StringHolder(const string& s)
-  : string_(&s),
-    cstring_(NULL),
-    len_(s.size())
+  : absl::AlphaNum(s)
 {}
 
-StringHolder::StringHolder(const char* s)
-  : string_(NULL),
-    cstring_(s),
-    len_(std::strlen(s))
+StringHolder::StringHolder(const char* cp)
+  : absl::AlphaNum(cp)
 {}
 
 StringHolder::StringHolder(uint64 n)
-  : converted_string_(SimpleItoa(n)),
-    string_(&converted_string_),
-    cstring_(NULL),
-    len_(converted_string_.length())
+  : absl::AlphaNum(n)
 {}
 
 StringHolder::~StringHolder() {}
@@ -192,9 +139,9 @@ StringHolder::~StringHolder() {}
 
 // Implements s += sh; (s: string, sh: StringHolder)
 string& operator+=(string& lhs, const StringHolder& rhs) {
-  const string* const s = rhs.GetString();
-  if (s) {
-    lhs += *s;
+  absl::string_view s = rhs.GetString();;
+  if (s.size() != 0) {
+    lhs += s.data();
   } else {
     const char* const cs = rhs.GetCString();
     if (cs)
@@ -204,87 +151,36 @@ string& operator+=(string& lhs, const StringHolder& rhs) {
 }
 
 string StrCat(const StringHolder& s1, const StringHolder& s2) {
-  string result;
-  result.reserve(s1.Length() + s2.Length() + 1);
-
-  result += s1;
-  result += s2;
-
-  return result;
+  return absl::StrCat(s1, s2);
 }
 
 string StrCat(const StringHolder& s1, const StringHolder& s2,
               const StringHolder& s3) {
-  string result;
-  result.reserve(s1.Length() + s2.Length() + s3.Length() + 1);
-
-  result += s1;
-  result += s2;
-  result += s3;
-
-  return result;
+  return absl::StrCat(s1, s2, s3);
 }
 
 string StrCat(const StringHolder& s1, const StringHolder& s2,
               const StringHolder& s3, const StringHolder& s4) {
-  string result;
-  result.reserve(s1.Length() + s2.Length() + s3.Length() + s4.Length() + 1);
-
-  result += s1;
-  result += s2;
-  result += s3;
-  result += s4;
-
-  return result;
+  return absl::StrCat(s1, s2, s3, s4);
 }
 
 string StrCat(const StringHolder& s1, const StringHolder& s2,
               const StringHolder& s3, const StringHolder& s4,
               const StringHolder& s5) {
-  string result;
-  result.reserve(s1.Length() + s2.Length() + s3.Length() + s4.Length() +
-                 s5.Length() + 1);
-  result += s1;
-  result += s2;
-  result += s3;
-  result += s4;
-  result += s5;
-
-  return result;
+  return absl::StrCat(s1, s2, s3, s4, s5);
 }
 
 string StrCat(const StringHolder& s1, const StringHolder& s2,
               const StringHolder& s3, const StringHolder& s4,
               const StringHolder& s5, const StringHolder& s6) {
-  string result;
-  result.reserve(s1.Length() + s2.Length() + s3.Length() + s4.Length() +
-                 s5.Length() + s6.Length() + 1);
-  result += s1;
-  result += s2;
-  result += s3;
-  result += s4;
-  result += s5;
-  result += s6;
-
-  return result;
+  return absl::StrCat(s1, s2, s3, s4, s5, s6);
 }
 
 string StrCat(const StringHolder& s1, const StringHolder& s2,
               const StringHolder& s3, const StringHolder& s4,
               const StringHolder& s5, const StringHolder& s6,
               const StringHolder& s7) {
-  string result;
-  result.reserve(s1.Length() + s2.Length() + s3.Length() + s4.Length() +
-                 s5.Length() + s6.Length() + s7.Length() + 1);
-  result += s1;
-  result += s2;
-  result += s3;
-  result += s4;
-  result += s5;
-  result += s6;
-  result += s7;
-
-  return result;
+  return absl::StrCat(s1, s2, s3, s4, s5, s6, s7);
 }
 
 string StrCat(const StringHolder& s1, const StringHolder& s2,
@@ -294,16 +190,7 @@ string StrCat(const StringHolder& s1, const StringHolder& s2,
   string result;
   result.reserve(s1.Length() + s2.Length() + s3.Length() + s4.Length() +
                  s5.Length() + s6.Length() + s7.Length() + s8.Length() + 1);
-  result += s1;
-  result += s2;
-  result += s3;
-  result += s4;
-  result += s5;
-  result += s6;
-  result += s7;
-  result += s8;
-
-  return result;
+  return absl::StrCat(s1, s2, s3, s4, s5, s6, s7, s8);
 }
 
 string StrCat(const StringHolder& s1, const StringHolder& s2,
@@ -311,21 +198,7 @@ string StrCat(const StringHolder& s1, const StringHolder& s2,
               const StringHolder& s5, const StringHolder& s6,
               const StringHolder& s7, const StringHolder& s8,
               const StringHolder& s9) {
-  string result;
-  result.reserve(s1.Length() + s2.Length() + s3.Length() + s4.Length() +
-                 s5.Length() + s6.Length() + s7.Length() + s8.Length() +
-                 s9.Length() + 1);
-  result += s1;
-  result += s2;
-  result += s3;
-  result += s4;
-  result += s5;
-  result += s6;
-  result += s7;
-  result += s8;
-  result += s9;
-
-  return result;
+  return absl::StrCat(s1, s2, s3, s4, s5, s6, s7, s8, s9);
 }
 
 string StrCat(const StringHolder& s1, const StringHolder& s2,
@@ -334,23 +207,7 @@ string StrCat(const StringHolder& s1, const StringHolder& s2,
               const StringHolder& s7, const StringHolder& s8,
               const StringHolder& s9, const StringHolder& s10,
               const StringHolder& s11) {
-  string result;
-  result.reserve(s1.Length() + s2.Length()  + s3.Length() + s4.Length() +
-                 s5.Length() + s6.Length()  + s7.Length() + s8.Length() +
-                 s9.Length() + s10.Length() + s11.Length());
-  result += s1;
-  result += s2;
-  result += s3;
-  result += s4;
-  result += s5;
-  result += s6;
-  result += s7;
-  result += s8;
-  result += s9;
-  result += s10;
-  result += s11;
-
-  return result;
+  return absl::StrCat(s1, s2, s3, s4, s5, s6, s7, s8, s9, s10, s11);
 }
 
 string StrCat(const StringHolder& s1, const StringHolder& s2,
@@ -359,24 +216,7 @@ string StrCat(const StringHolder& s1, const StringHolder& s2,
               const StringHolder& s7, const StringHolder& s8,
               const StringHolder& s9, const StringHolder& s10,
               const StringHolder& s11, const StringHolder& s12) {
-  string result;
-  result.reserve(s1.Length() + s2.Length()  + s3.Length() + s4.Length() +
-                 s5.Length() + s6.Length()  + s7.Length() + s8.Length() +
-                 s9.Length() + s10.Length() + s11.Length() + s12.Length());
-  result += s1;
-  result += s2;
-  result += s3;
-  result += s4;
-  result += s5;
-  result += s6;
-  result += s7;
-  result += s8;
-  result += s9;
-  result += s10;
-  result += s11;
-  result += s12;
-
-  return result;
+  return absl::StrCat(s1, s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12);
 }
 
 string StrCat(const StringHolder& s1, const StringHolder& s2,
@@ -386,26 +226,8 @@ string StrCat(const StringHolder& s1, const StringHolder& s2,
               const StringHolder& s9, const StringHolder& s10,
               const StringHolder& s11, const StringHolder& s12,
               const StringHolder& s13) {
-  string result;
-  result.reserve(s1.Length() + s2.Length()  + s3.Length() + s4.Length() +
-                 s5.Length() + s6.Length()  + s7.Length() + s8.Length() +
-                 s9.Length() + s10.Length() + s11.Length() + s12.Length() +
-                 s13.Length());
-  result += s1;
-  result += s2;
-  result += s3;
-  result += s4;
-  result += s5;
-  result += s6;
-  result += s7;
-  result += s8;
-  result += s9;
-  result += s10;
-  result += s11;
-  result += s12;
-  result += s13;
-
-  return result;
+  return absl::StrCat(s1, s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12,
+                      s13);
 }
 
 string StrCat(const StringHolder& s1, const StringHolder& s2,
@@ -415,27 +237,8 @@ string StrCat(const StringHolder& s1, const StringHolder& s2,
               const StringHolder& s9, const StringHolder& s10,
               const StringHolder& s11, const StringHolder& s12,
               const StringHolder& s13, const StringHolder& s14) {
-  string result;
-  result.reserve(s1.Length() + s2.Length()  + s3.Length() + s4.Length() +
-                 s5.Length() + s6.Length()  + s7.Length() + s8.Length() +
-                 s9.Length() + s10.Length() + s11.Length() + s12.Length() +
-                 s13.Length() + s14.Length());
-  result += s1;
-  result += s2;
-  result += s3;
-  result += s4;
-  result += s5;
-  result += s6;
-  result += s7;
-  result += s8;
-  result += s9;
-  result += s10;
-  result += s11;
-  result += s12;
-  result += s13;
-  result += s14;
-
-  return result;
+  return absl::StrCat(s1, s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12,
+                      s13, s14);
 }
 
 string StrCat(const StringHolder& s1, const StringHolder& s2,
@@ -446,28 +249,8 @@ string StrCat(const StringHolder& s1, const StringHolder& s2,
               const StringHolder& s11, const StringHolder& s12,
               const StringHolder& s13, const StringHolder& s14,
               const StringHolder& s15) {
-  string result;
-  result.reserve(s1.Length() + s2.Length()  + s3.Length() + s4.Length() +
-                 s5.Length() + s6.Length()  + s7.Length() + s8.Length() +
-                 s9.Length() + s10.Length() + s11.Length() + s12.Length() +
-                 s13.Length() + s14.Length() + s15.Length());
-  result += s1;
-  result += s2;
-  result += s3;
-  result += s4;
-  result += s5;
-  result += s6;
-  result += s7;
-  result += s8;
-  result += s9;
-  result += s10;
-  result += s11;
-  result += s12;
-  result += s13;
-  result += s14;
-  result += s15;
-
-  return result;
+  return absl::StrCat(s1, s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12,
+                      s13, s14, s15);
 }
 
 string StrCat(const StringHolder& s1, const StringHolder& s2,
@@ -478,83 +261,35 @@ string StrCat(const StringHolder& s1, const StringHolder& s2,
               const StringHolder& s11, const StringHolder& s12,
               const StringHolder& s13, const StringHolder& s14,
               const StringHolder& s15, const StringHolder& s16) {
-  string result;
-  result.reserve(s1.Length() + s2.Length()  + s3.Length() + s4.Length() +
-                 s5.Length() + s6.Length()  + s7.Length() + s8.Length() +
-                 s9.Length() + s10.Length() + s11.Length() + s12.Length() +
-                 s13.Length() + s14.Length() + s15.Length() + s16.Length());
-  result += s1;
-  result += s2;
-  result += s3;
-  result += s4;
-  result += s5;
-  result += s6;
-  result += s7;
-  result += s8;
-  result += s9;
-  result += s10;
-  result += s11;
-  result += s12;
-  result += s13;
-  result += s14;
-  result += s15;
-  result += s16;
-
-  return result;
+  return absl::StrCat(s1, s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12,
+                      s13, s14, s15, s16);
 }
 
 // StrAppend
 
 void StrAppend(string* dest, const StringHolder& s1) {
-  assert(dest);
-
-  dest->reserve(dest->length() + s1.Length() + 1);
-  *dest += s1;
+  absl::StrAppend(dest, s1);
 }
 
 void StrAppend(string* dest, const StringHolder& s1, const StringHolder& s2) {
-  assert(dest);
-
-  dest->reserve(dest->length() + s1.Length() + s2.Length() + 1);
-  *dest += s1;
-  *dest += s2;
+  absl::StrAppend(dest, s1, s2);
 }
 
 void StrAppend(string* dest, const StringHolder& s1, const StringHolder& s2,
                const StringHolder& s3) {
-  assert(dest);
-
-  dest->reserve(dest->length() + s1.Length() + s2.Length() + s3.Length() + 1);
-  *dest += s1;
-  *dest += s2;
-  *dest += s3;
+  absl::StrAppend(dest, s1, s2, s3);
 }
 
 void StrAppend(string* dest, const StringHolder& s1, const StringHolder& s2,
                const StringHolder& s3, const StringHolder& s4) {
-  assert(dest);
-
-  dest->reserve(dest->length() + s1.Length() + s2.Length() + s3.Length() +
-      s4.Length() + 1);
-  *dest += s1;
-  *dest += s2;
-  *dest += s3;
-  *dest += s4;
+  absl::StrAppend(dest, s1, s2, s3, s4);
 }
 
 void StrAppend(string* dest, const StringHolder& s1, const StringHolder& s2,
                const StringHolder& s3, const StringHolder& s4,
                const StringHolder& s5) {
-  assert(dest);
-
-  dest->reserve(dest->length() + s1.Length() + s2.Length() + s3.Length() +
-      s4.Length() + s5.Length() + 1);
-  *dest += s1;
-  *dest += s2;
-  *dest += s3;
-  *dest += s4;
-  *dest += s5;
+  absl::StrAppend(dest, s1, s2, s3, s4, s5);
 }
 
 }  // namespace phonenumbers
-}  // namespace i18n
+}  // namespace i18n

cpp/src/phonenumbers/stringutil.h

@@ -22,6 +22,8 @@
 #include <vector>
 
 #include "phonenumbers/base/basictypes.h"
+#include "absl/strings/string_view.h"
+#include "absl/strings/str_cat.h"
 
 namespace i18n {
 namespace phonenumbers {
@@ -46,13 +48,9 @@ size_t FindNth(const string& s, char c, int n);
 
 // Splits a string using a character delimiter. Appends the components to the
 // provided vector. Note that empty tokens are ignored.
-void SplitStringUsing(const string& s, const string& delimiter,
+void SplitStringUsing(const string& s, char delimiter,
                       vector<string>* result);
 
-// Replaces any occurrence of the character 'remove' (or the characters
-// in 'remove') with the character 'replacewith'.
-void StripString(string* s, const char* remove, char replacewith);
-
 // Returns true if 'in' starts with 'prefix' and writes 'in' minus 'prefix' into
 // 'out'.
 bool TryStripPrefixString(const string& in, const string& prefix, string* out);
@@ -77,9 +75,9 @@ void strrmm(string* s, const string& chars);
 int GlobalReplaceSubstring(const string& substring, const string& replacement,
                            string* s);
 
-// Holds a reference to a std::string or C string. It can also be constructed
-// from an integer which is converted to a string.
-class StringHolder {
+// An abstract to absl::AlphaNum type; AlphaNum has more accomidating
+// constructors for more types.
+class StringHolder: public absl::AlphaNum {
  public:
   // Don't make the constructors explicit to make the StrCat usage convenient.
   StringHolder(const string& s);  // NOLINT(runtime/explicit)
@@ -87,23 +85,17 @@ class StringHolder {
   StringHolder(uint64 n);         // NOLINT(runtime/explicit)
   ~StringHolder();
 
-  const string* GetString() const {
-    return string_;
+  const absl::string_view GetString() const {
+    return Piece();
   }
 
   const char* GetCString() const {
-    return cstring_;
+    return data();
   }
 
   size_t Length() const {
-    return len_;
+    return size();
   }
-
- private:
-  const string converted_string_;  // Stores the string converted from integer.
-  const string* const string_;
-  const char* const cstring_;
-  const size_t len_;
 };
 
 string& operator+=(string& lhs, const StringHolder& rhs);

cpp/test/phonenumbers/stringutil_test.cc

@@ -60,19 +60,13 @@ TEST(StringUtilTest, FindNth) {
 
 TEST(StringUtilTest, SplitStringUsingWithEmptyString) {
   vector<string> result;
-  SplitStringUsing("", ":", &result);
-  EXPECT_EQ(0U, result.size());
-}
-
-TEST(StringUtilTest, SplitStringUsingWithEmptyDelimiter) {
-  vector<string> result;
-  SplitStringUsing("hello", "", &result);
+  SplitStringUsing("", ':', &result);
   EXPECT_EQ(0U, result.size());
 }
 
 TEST(StringUtilTest, SplitStringUsing) {
   vector<string> result;
-  SplitStringUsing(":hello:world:", ":", &result);
+  SplitStringUsing(":hello:world:", ':', &result);
   EXPECT_EQ(2U, result.size());
   EXPECT_EQ("hello", result[0]);
   EXPECT_EQ("world", result[1]);
@@ -80,7 +74,7 @@ TEST(StringUtilTest, SplitStringUsing) {
 
 TEST(StringUtilTest, SplitStringUsingIgnoresEmptyToken) {
   vector<string> result;
-  SplitStringUsing("hello::world", ":", &result);
+  SplitStringUsing("hello::world", ':', &result);
   EXPECT_EQ(2U, result.size());
   EXPECT_EQ("hello", result[0]);
   EXPECT_EQ("world", result[1]);
@@ -195,13 +189,11 @@ TEST(StringUtilTest, StringHolder) {
   static const char cstring[] = "aaa";
   StringHolder sh1(cstring);
   EXPECT_EQ(cstring, sh1.GetCString());
-  EXPECT_EQ(NULL, sh1.GetString());
 
-  // Test with std::string.
-  string s = "bbb";
+  // Test with absl::string_view.
+  string s = "aaa";
   StringHolder sh2(s);
-  EXPECT_EQ(NULL, sh2.GetCString());
-  EXPECT_EQ(&s, sh2.GetString());
+  EXPECT_EQ(cstring, sh2.GetString());
 
   // Test GetLength().
   string s2 = "hello";
@@ -210,9 +202,8 @@ TEST(StringUtilTest, StringHolder) {
 
   // Test with uint64.
   StringHolder sh4(42);
-  EXPECT_TRUE(sh4.GetCString() == NULL);
-  EXPECT_EQ(2U, sh4.Length());
-  EXPECT_EQ("42", *sh4.GetString());
+  static const char cstring2[] = "42";;
+  EXPECT_EQ(cstring2, sh4.GetString());
 }
 
 // Test the operator+=(string& lhs, const StringHolder& rhs) implementation.

tools/cpp/CMakeLists.txt

@@ -64,7 +64,7 @@ endif ()
 include_directories ("src")
 
 add_executable (generate_geocoding_data ${SOURCES})
-target_link_libraries (generate_geocoding_data absl::strings absl::btree)
+target_link_libraries (generate_geocoding_data absl::strings absl::btree absl::node_hash_set)
 
 set (TEST_SOURCES
   "src/cpp-build/generate_geocoding_data.cc"
@@ -81,4 +81,4 @@ endif ()
 # Build the testing binary.
 include_directories ("test")
 add_executable (generate_geocoding_data_test ${TEST_SOURCES})
-target_link_libraries (generate_geocoding_data_test absl::btree ${TEST_LIBS})
+target_link_libraries (generate_geocoding_data_test absl::btree ${TEST_LIBS} absl::node_hash_set)