From a94318b0b1f0c4b8a2a4d6757b073626af06deea Mon Sep 17 00:00:00 2001
From: Tim King <taking@google.com>
Date: Thu, 13 Jul 2017 17:35:00 -0700
Subject: [PATCH] Cleaning up the CVC4::String class.

---
 src/theory/strings/regexp_operation.cpp |   4 +-
 src/util/regexp.cpp                     | 368 +++++++++++++++++-----
 src/util/regexp.h                       | 394 +++++-------------------
 3 files changed, 378 insertions(+), 388 deletions(-)

diff --git a/src/theory/strings/regexp_operation.cpp b/src/theory/strings/regexp_operation.cpp
index ec788fa78..a98a2a0ef 100644
--- a/src/theory/strings/regexp_operation.cpp
+++ b/src/theory/strings/regexp_operation.cpp
@@ -1326,14 +1326,14 @@ void RegExpOpr::getCharSet( Node r, std::set<unsigned char> &pcset, SetNodes &pv
         Node st = Rewriter::rewrite(r[0]);
         if(st.isConst()) {
           CVC4::String s = st.getConst< CVC4::String >();
-          s.getCharSet( cset );
+          cset.insert(s.getVec().begin(), s.getVec().end());
         } else if(st.getKind() == kind::VARIABLE) {
           vset.insert( st );
         } else {
           for(unsigned i=0; i<st.getNumChildren(); i++) {
             if(st[i].isConst()) {
               CVC4::String s = st[i].getConst< CVC4::String >();
-              s.getCharSet( cset );
+              cset.insert(s.getVec().begin(), s.getVec().end());
             } else {
               vset.insert( st[i] );
             }
diff --git a/src/util/regexp.cpp b/src/util/regexp.cpp
index 9915d480d..6afadfd5b 100644
--- a/src/util/regexp.cpp
+++ b/src/util/regexp.cpp
@@ -17,105 +17,194 @@
 
 #include "util/regexp.h"
 
+#include <algorithm>
+#include <climits>
 #include <iomanip>
 #include <iostream>
+#include <sstream>
+
+#include "base/cvc4_assert.h"
+#include "base/exception.h"
 
 using namespace std;
 
 namespace CVC4 {
 
-void String::toInternal(const std::string &s) {
-  d_str.clear();
-  unsigned i=0;
-  while(i < s.size()) {
-    if(s[i] == '\\') {
+static_assert(UCHAR_MAX == 255, "Unsigned char is assumed to have 256 values.");
+
+int String::cmp(const String &y) const {
+  if (size() != y.size()) {
+    return size() < y.size() ? 1 : -1;
+  }
+  for (unsigned int i = 0; i < size(); ++i) {
+    if (d_str[i] != y.d_str[i]) {
+      return getUnsignedCharAt(i) < y.getUnsignedCharAt(i) ? 1 : -1;
+    }
+  }
+  return 0;
+}
+
+String String::concat(const String &other) const {
+  std::vector<unsigned int> ret_vec(d_str);
+  ret_vec.insert(ret_vec.end(), other.d_str.begin(), other.d_str.end());
+  return String(ret_vec);
+}
+
+bool String::strncmp(const String &y, const std::size_t np) const {
+  std::size_t n = np;
+  std::size_t b = (size() >= y.size()) ? size() : y.size();
+  std::size_t s = (size() <= y.size()) ? size() : y.size();
+  if (n > s) {
+    if (b == s) {
+      n = s;
+    } else {
+      return false;
+    }
+  }
+  for (std::size_t i = 0; i < n; ++i) {
+    if (d_str[i] != y.d_str[i]) return false;
+  }
+  return true;
+}
+
+bool String::rstrncmp(const String &y, const std::size_t np) const {
+  std::size_t n = np;
+  std::size_t b = (size() >= y.size()) ? size() : y.size();
+  std::size_t s = (size() <= y.size()) ? size() : y.size();
+  if (n > s) {
+    if (b == s) {
+      n = s;
+    } else {
+      return false;
+    }
+  }
+  for (std::size_t i = 0; i < n; ++i) {
+    if (d_str[size() - i - 1] != y.d_str[y.size() - i - 1]) return false;
+  }
+  return true;
+}
+
+std::vector<unsigned> String::toInternal(const std::string &s) {
+  std::vector<unsigned> str;
+  unsigned i = 0;
+  while (i < s.size()) {
+    if (s[i] == '\\') {
       i++;
-      if(i < s.size()) {
-        switch(s[i]) {
-          case 'n':  {d_str.push_back( convertCharToUnsignedInt('\n') );i++;} break;
-          case 't':  {d_str.push_back( convertCharToUnsignedInt('\t') );i++;} break;
-          case 'v':  {d_str.push_back( convertCharToUnsignedInt('\v') );i++;} break;
-          case 'b':  {d_str.push_back( convertCharToUnsignedInt('\b') );i++;} break;
-          case 'r':  {d_str.push_back( convertCharToUnsignedInt('\r') );i++;} break;
-          case 'f':  {d_str.push_back( convertCharToUnsignedInt('\f') );i++;} break;
-          case 'a':  {d_str.push_back( convertCharToUnsignedInt('\a') );i++;} break;
-          case '\\': {d_str.push_back( convertCharToUnsignedInt('\\') );i++;} break;
+      if (i < s.size()) {
+        switch (s[i]) {
+          case 'n': {
+            str.push_back(convertCharToUnsignedInt('\n'));
+            i++;
+          } break;
+          case 't': {
+            str.push_back(convertCharToUnsignedInt('\t'));
+            i++;
+          } break;
+          case 'v': {
+            str.push_back(convertCharToUnsignedInt('\v'));
+            i++;
+          } break;
+          case 'b': {
+            str.push_back(convertCharToUnsignedInt('\b'));
+            i++;
+          } break;
+          case 'r': {
+            str.push_back(convertCharToUnsignedInt('\r'));
+            i++;
+          } break;
+          case 'f': {
+            str.push_back(convertCharToUnsignedInt('\f'));
+            i++;
+          } break;
+          case 'a': {
+            str.push_back(convertCharToUnsignedInt('\a'));
+            i++;
+          } break;
+          case '\\': {
+            str.push_back(convertCharToUnsignedInt('\\'));
+            i++;
+          } break;
           case 'x': {
-            if(i + 2 < s.size()) {
-              if(isxdigit(s[i+1]) && isxdigit(s[i+2])) {
-                d_str.push_back( convertCharToUnsignedInt( hexToDec(s[i+1]) * 16 + hexToDec(s[i+2]) ) );
+            if (i + 2 < s.size()) {
+              if (isxdigit(s[i + 1]) && isxdigit(s[i + 2])) {
+                str.push_back(convertCharToUnsignedInt(hexToDec(s[i + 1]) * 16 +
+                                                       hexToDec(s[i + 2])));
                 i += 3;
               } else {
-                throw CVC4::Exception( "Illegal String Literal: \"" + s + "\"" );
+                throw CVC4::Exception("Illegal String Literal: \"" + s + "\"");
               }
             } else {
-              throw CVC4::Exception( "Illegal String Literal: \"" + s + "\", must have two digits after \\x" );
+              throw CVC4::Exception("Illegal String Literal: \"" + s +
+                                    "\", must have two digits after \\x");
             }
-          }
-          break;
+          } break;
           default: {
-            if(isdigit(s[i])) {
+            if (isdigit(s[i])) {
               int num = (int)s[i] - (int)'0';
               bool flag = num < 4;
-              if(i+1 < s.size() && num < 8 && isdigit(s[i+1]) && s[i+1] < '8') {
-                num = num * 8 + (int)s[i+1] - (int)'0';
-                if(flag && i+2 < s.size() && isdigit(s[i+2]) && s[i+2] < '8') {
-                  num = num * 8 + (int)s[i+2] - (int)'0';
-                  d_str.push_back( convertCharToUnsignedInt((unsigned char)num) );
+              if (i + 1 < s.size() && num < 8 && isdigit(s[i + 1]) &&
+                  s[i + 1] < '8') {
+                num = num * 8 + (int)s[i + 1] - (int)'0';
+                if (flag && i + 2 < s.size() && isdigit(s[i + 2]) &&
+                    s[i + 2] < '8') {
+                  num = num * 8 + (int)s[i + 2] - (int)'0';
+                  str.push_back(convertCharToUnsignedInt((unsigned char)num));
                   i += 3;
                 } else {
-                  d_str.push_back( convertCharToUnsignedInt((unsigned char)num) );
+                  str.push_back(convertCharToUnsignedInt((unsigned char)num));
                   i += 2;
                 }
               } else {
-                d_str.push_back( convertCharToUnsignedInt((unsigned char)num) );
+                str.push_back(convertCharToUnsignedInt((unsigned char)num));
                 i++;
               }
-            } else if((unsigned)s[i] > 127) {
-              throw CVC4::Exception( "Illegal String Literal: \"" + s + "\", must use escaped sequence" );
+            } else if ((unsigned)s[i] > 127) {
+              throw CVC4::Exception("Illegal String Literal: \"" + s +
+                                    "\", must use escaped sequence");
             } else {
-              d_str.push_back( convertCharToUnsignedInt(s[i]) );
+              str.push_back(convertCharToUnsignedInt(s[i]));
               i++;
             }
           }
         }
       } else {
-        throw CVC4::Exception( "should be handled by lexer: \"" + s + "\"" );
-        //d_str.push_back( convertCharToUnsignedInt('\\') );
+        throw CVC4::Exception("should be handled by lexer: \"" + s + "\"");
+        // str.push_back( convertCharToUnsignedInt('\\') );
       }
-    } else if((unsigned)s[i] > 127) {
-      throw CVC4::Exception( "Illegal String Literal: \"" + s + "\", must use escaped sequence" );
+    } else if ((unsigned)s[i] > 127) {
+      throw CVC4::Exception("Illegal String Literal: \"" + s +
+                            "\", must use escaped sequence");
     } else {
-      d_str.push_back( convertCharToUnsignedInt(s[i]) );
+      str.push_back(convertCharToUnsignedInt(s[i]));
       i++;
     }
   }
+  return str;
 }
 
-void String::getCharSet(std::set<unsigned char> &cset) const {
-  for(std::vector<unsigned int>::const_iterator itr = d_str.begin();
-    itr != d_str.end(); itr++) {
-      cset.insert( convertUnsignedIntToChar(*itr) );
-    }
+unsigned char String::getUnsignedCharAt(size_t pos) const {
+  Assert(pos < size());
+  return convertUnsignedIntToChar(d_str[pos]);
 }
 
-std::size_t String::overlap(String &y) const {
-  std::size_t i = d_str.size() < y.size() ? d_str.size() : y.size();
-  for(; i>0; i--) {
+std::size_t String::overlap(const String &y) const {
+  std::size_t i = size() < y.size() ? size() : y.size();
+  for (; i > 0; i--) {
     String s = suffix(i);
     String p = y.prefix(i);
-    if(s == p) {
+    if (s == p) {
       return i;
     }
   }
   return i;
 }
-std::size_t String::roverlap(String &y) const {
-  std::size_t i = d_str.size() < y.size() ? d_str.size() : y.size();
-  for(; i>0; i--) {
+
+std::size_t String::roverlap(const String &y) const {
+  std::size_t i = size() < y.size() ? size() : y.size();
+  for (; i > 0; i--) {
     String s = prefix(i);
     String p = y.suffix(i);
-    if(s == p) {
+    if (s == p) {
       return i;
     }
   }
@@ -124,36 +213,53 @@ std::size_t String::roverlap(String &y) const {
 
 std::string String::toString() const {
   std::string str;
-  for(unsigned int i=0; i<d_str.size(); ++i) {
-    unsigned char c = convertUnsignedIntToChar( d_str[i] );
-    if(isprint( c )) {
-      if(c == '\\') {
+  for (unsigned int i = 0; i < size(); ++i) {
+    unsigned char c = convertUnsignedIntToChar(d_str[i]);
+    if (isprint(c)) {
+      if (c == '\\') {
         str += "\\\\";
-      } 
-      //else if(c == '\"') {
+      }
+      // else if(c == '\"') {
       //  str += "\\\"";
-      //} 
+      //}
       else {
         str += c;
       }
     } else {
       std::string s;
-      switch(c) {
-        case '\a': s = "\\a"; break;
-        case '\b': s = "\\b"; break;
-        case '\t': s = "\\t"; break;
-        case '\r': s = "\\r"; break;
-        case '\v': s = "\\v"; break;
-        case '\f': s = "\\f"; break;
-        case '\n': s = "\\n"; break;
-        case '\e': s = "\\e"; break;
-        default  : {
+      switch (c) {
+        case '\a':
+          s = "\\a";
+          break;
+        case '\b':
+          s = "\\b";
+          break;
+        case '\t':
+          s = "\\t";
+          break;
+        case '\r':
+          s = "\\r";
+          break;
+        case '\v':
+          s = "\\v";
+          break;
+        case '\f':
+          s = "\\f";
+          break;
+        case '\n':
+          s = "\\n";
+          break;
+        case '\e':
+          s = "\\e";
+          break;
+        default: {
           std::stringstream ss;
-          ss << std::setfill ('0') << std::setw(2) << std::hex << ((int)c);
+          ss << std::setfill('0') << std::setw(2) << std::hex << ((int)c);
           std::string t = ss.str();
-          t = t.substr(t.size()-2, 2);
+          t = t.substr(t.size() - 2, 2);
           s = "\\x" + t;
-          //std::string s2 = static_cast<std::ostringstream*>( &(std::ostringstream() << (int)c) )->str();
+          // std::string s2 = static_cast<std::ostringstream*>(
+          // &(std::ostringstream() << (int)c) )->str();
         }
       }
       str += s;
@@ -162,12 +268,126 @@ std::string String::toString() const {
   return str;
 }
 
-std::ostream& operator <<(std::ostream& os, const String& s) {
+bool String::isRepeated() const {
+  if (size() > 1) {
+    unsigned int f = d_str[0];
+    for (unsigned i = 1; i < size(); ++i) {
+      if (f != d_str[i]) return false;
+    }
+  }
+  return true;
+}
+
+bool String::tailcmp(const String &y, int &c) const {
+  int id_x = size() - 1;
+  int id_y = y.size() - 1;
+  while (id_x >= 0 && id_y >= 0) {
+    if (d_str[id_x] != y.d_str[id_y]) {
+      c = id_x;
+      return false;
+    }
+    --id_x;
+    --id_y;
+  }
+  c = id_x == -1 ? (-(id_y + 1)) : (id_x + 1);
+  return true;
+}
+
+std::size_t String::find(const String &y, const std::size_t start) const {
+  if (size() < y.size() + start) return std::string::npos;
+  if (y.empty()) return start;
+  if (empty()) return std::string::npos;
+
+  std::vector<unsigned>::const_iterator itr = std::search(
+      d_str.begin() + start, d_str.end(), y.d_str.begin(), y.d_str.end());
+  if (itr != d_str.end()) {
+    return itr - d_str.begin();
+  }
+  return std::string::npos;
+}
+
+std::size_t String::rfind(const String &y, const std::size_t start) const {
+  if (size() < y.size() + start) return std::string::npos;
+  if (y.empty()) return start;
+  if (empty()) return std::string::npos;
+
+  std::vector<unsigned>::const_reverse_iterator itr = std::search(
+      d_str.rbegin() + start, d_str.rend(), y.d_str.rbegin(), y.d_str.rend());
+  if (itr != d_str.rend()) {
+    return itr - d_str.rbegin();
+  }
+  return std::string::npos;
+}
+
+String String::replace(const String &s, const String &t) const {
+  std::size_t ret = find(s);
+  if (ret != std::string::npos) {
+    std::vector<unsigned int> vec;
+    vec.insert(vec.begin(), d_str.begin(), d_str.begin() + ret);
+    vec.insert(vec.end(), t.d_str.begin(), t.d_str.end());
+    vec.insert(vec.end(), d_str.begin() + ret + s.size(), d_str.end());
+    return String(vec);
+  } else {
+    return *this;
+  }
+}
+
+String String::substr(std::size_t i) const {
+  Assert(i <= size());
+  std::vector<unsigned int> ret_vec;
+  std::vector<unsigned int>::const_iterator itr = d_str.begin() + i;
+  ret_vec.insert(ret_vec.end(), itr, d_str.end());
+  return String(ret_vec);
+}
+
+String String::substr(std::size_t i, std::size_t j) const {
+  Assert(i + j <= size());
+  std::vector<unsigned int> ret_vec;
+  std::vector<unsigned int>::const_iterator itr = d_str.begin() + i;
+  ret_vec.insert(ret_vec.end(), itr, itr + j);
+  return String(ret_vec);
+}
+
+bool String::isNumber() const {
+  for (unsigned character : d_str) {
+    unsigned char c = convertUnsignedIntToChar(character);
+    if (c < '0' || c > '9') {
+      return false;
+    }
+  }
+  return true;
+}
+
+int String::toNumber() const {
+  if (isNumber()) {
+    int ret = 0;
+    for (unsigned int i = 0; i < size(); ++i) {
+      unsigned char c = convertUnsignedIntToChar(d_str[i]);
+      ret = ret * 10 + (int)c - (int)'0';
+    }
+    return ret;
+  } else {
+    return -1;
+  }
+}
+
+unsigned char String::hexToDec(unsigned char c) {
+  if (c >= '0' && c <= '9') {
+    return c - '0';
+  } else if (c >= 'a' && c <= 'f') {
+    return c - 'a' + 10;
+  } else {
+    Assert(c >= 'A' && c <= 'F');
+    return c - 'A' + 10;
+  }
+}
+
+std::ostream &operator<<(std::ostream &os, const String &s) {
   return os << "\"" << s.toString() << "\"";
 }
 
-std::ostream& operator<<(std::ostream& out, const RegExp& s) {
+std::ostream &operator<<(std::ostream &out, const RegExp &s) {
   return out << "regexp(" << s.getType() << ')';
 }
 
-}/* CVC4 namespace */
+}  // namespace CVC4
diff --git a/src/util/regexp.h b/src/util/regexp.h
index beb0ee097..9fb8aea60 100644
--- a/src/util/regexp.h
+++ b/src/util/regexp.h
@@ -20,363 +20,133 @@
 #ifndef __CVC4__REGEXP_H
 #define __CVC4__REGEXP_H
 
-#include <vector>
+#include <cstddef>
+#include <ostream>
 #include <string>
-#include <set>
-#include <sstream>
-#include <cassert>
-
-#include "base/exception.h"
-#include "util/hash.h"
+#include <vector>
 
 namespace CVC4 {
 
 class CVC4_PUBLIC String {
-public:
-  static unsigned convertCharToUnsignedInt( unsigned char c ) {
+ public:
+  static unsigned convertCharToUnsignedInt(unsigned char c) {
     unsigned i = c;
     i = i + 191;
-    return (i>=256 ? i-256 : i);
+    return (i >= 256 ? i - 256 : i);
   }
-  static unsigned char convertUnsignedIntToChar( unsigned i ){
-    unsigned ii = i+65;
-    return (unsigned char)(ii>=256 ? ii-256 : ii);
+  static unsigned char convertUnsignedIntToChar(unsigned i) {
+    unsigned ii = i + 65;
+    return (unsigned char)(ii >= 256 ? ii - 256 : ii);
   }
-  static bool isPrintable( unsigned i ){
-    unsigned char c = convertUnsignedIntToChar( i );
-    return (c>=' ' && c<='~');//isprint( (int)c );
+  static bool isPrintable(unsigned i) {
+    unsigned char c = convertUnsignedIntToChar(i);
+    return (c >= ' ' && c <= '~');  // isprint( (int)c );
   }
 
-private:
-  std::vector<unsigned> d_str;
-
-  bool isVecSame(const std::vector<unsigned> &a, const std::vector<unsigned> &b) const {
-    if(a.size() != b.size()) return false;
-    else {
-      return std::equal(a.begin(), a.end(), b.begin());
-      //for(unsigned int i=0; i<a.size(); ++i)
-        //if(a[i] != b[i]) return false;
-      //return true;
-    }
-  }
+  String() = default;
+  explicit String(const std::string& s) : d_str(toInternal(s)) {}
+  explicit String(const char* s) : d_str(toInternal(std::string(s))) {}
+  explicit String(const unsigned char c)
+      : d_str({convertCharToUnsignedInt(c)}) {}
+  explicit String(const std::vector<unsigned>& s) : d_str(s) {}
 
-  //guarded
-  unsigned char hexToDec(unsigned char c) {
-    if(c>='0' && c<='9') {
-      return c - '0';
-    } else if (c >= 'a' && c <= 'f') {
-      return c - 'a' + 10;
-    } else {
-      assert(c >= 'A' && c <= 'F');
-      return c - 'A' + 10;
+  String& operator=(const String& y) {
+    if (this != &y) {
+      d_str = y.d_str;
     }
-  }
-
-  void toInternal(const std::string &s);
-
-public:
-  String() {}
-
-  String(const std::string &s) {
-    toInternal(s);
-  }
-
-  String(const char* s) {
-    std::string stmp(s);
-    toInternal(stmp);
-  }
-
-  String(const unsigned char c) {
-    d_str.push_back( convertCharToUnsignedInt(c) );
-  }
-
-  String(const std::vector<unsigned> &s) : d_str(s) { }
-
-  ~String() {}
-
-  String& operator =(const String& y) {
-    if(this != &y) d_str = y.d_str;
     return *this;
   }
 
-  bool operator ==(const String& y) const {
-    return isVecSame(d_str, y.d_str);
-  }
+  String concat(const String& other) const;
 
-  bool operator !=(const String& y) const {
-    return  ! ( isVecSame(d_str, y.d_str) );
-  }
-
-  String concat (const String& other) const {
-    std::vector<unsigned int> ret_vec(d_str);
-    ret_vec.insert( ret_vec.end(), other.d_str.begin(), other.d_str.end() );
-    return String(ret_vec);
-  }
+  bool operator==(const String& y) const { return cmp(y) == 0; }
+  bool operator!=(const String& y) const { return cmp(y) != 0; }
+  bool operator<(const String& y) const { return cmp(y) < 0; }
+  bool operator>(const String& y) const { return cmp(y) > 0; }
+  bool operator<=(const String& y) const { return cmp(y) <= 0; }
+  bool operator>=(const String& y) const { return cmp(y) >= 0; }
 
-  bool operator <(const String& y) const {
-    if(d_str.size() != y.d_str.size()) return d_str.size() < y.d_str.size();
-    else {
-      for(unsigned int i=0; i<d_str.size(); ++i)
-        if(d_str[i] != y.d_str[i]) return convertUnsignedIntToChar(d_str[i]) < convertUnsignedIntToChar(y.d_str[i]);
+  bool strncmp(const String& y, const std::size_t np) const;
+  bool rstrncmp(const String& y, const std::size_t np) const;
 
-      return false;
-    }
-  }
-
-  bool operator >(const String& y) const {
-    if(d_str.size() != y.d_str.size()) return d_str.size() > y.d_str.size();
-    else {
-      for(unsigned int i=0; i<d_str.size(); ++i)
-        if(d_str[i] != y.d_str[i]) return convertUnsignedIntToChar(d_str[i]) > convertUnsignedIntToChar(y.d_str[i]);
-
-      return false;
-    }
-  }
-
-  bool operator <=(const String& y) const {
-    if(d_str.size() != y.d_str.size()) return d_str.size() < y.d_str.size();
-    else {
-      for(unsigned int i=0; i<d_str.size(); ++i)
-        if(d_str[i] != y.d_str[i]) return convertUnsignedIntToChar(d_str[i]) < convertUnsignedIntToChar(y.d_str[i]);
-
-      return true;
-    }
-  }
-
-  bool operator >=(const String& y) const {
-    if(d_str.size() != y.d_str.size()) return d_str.size() > y.d_str.size();
-    else {
-      for(unsigned int i=0; i<d_str.size(); ++i)
-        if(d_str[i] != y.d_str[i]) return convertUnsignedIntToChar(d_str[i]) > convertUnsignedIntToChar(y.d_str[i]);
-
-      return true;
-    }
-  }
-
-  bool strncmp(const String &y, const std::size_t np) const {
-    std::size_t n = np;
-    std::size_t b = (d_str.size() >= y.d_str.size()) ? d_str.size() : y.d_str.size();
-    std::size_t s = (d_str.size() <= y.d_str.size()) ? d_str.size() : y.d_str.size();
-    if(n > s) {
-      if(b == s) {
-        n = s;
-      } else {
-        return false;
-      }
-    }
-    for(std::size_t i=0; i<n; ++i)
-      if(d_str[i] != y.d_str[i]) return false;
-    return true;
-  }
-
-  bool rstrncmp(const String &y, const std::size_t np) const {
-    std::size_t n = np;
-    std::size_t b = (d_str.size() >= y.d_str.size()) ? d_str.size() : y.d_str.size();
-    std::size_t s = (d_str.size() <= y.d_str.size()) ? d_str.size() : y.d_str.size();
-    if(n > s) {
-      if(b == s) {
-        n = s;
-      } else {
-        return false;
-      }
-    }
-    for(std::size_t i=0; i<n; ++i)
-      if(d_str[d_str.size() - i - 1] != y.d_str[y.d_str.size() - i - 1]) return false;
-    return true;
-  }
-
-  bool isEmptyString() const {
-    return ( d_str.size() == 0 );
-  }
-
-  /*char operator[] (const std::size_t i) const {
-    assert( i < d_str.size() );
-    return convertUnsignedIntToChar(d_str[i]);
-  }*/
   /*
    * Convenience functions
    */
   std::string toString() const;
+  bool empty() const { return d_str.empty(); }
+  bool isEmptyString() const { return empty(); }
+  std::size_t size() const { return d_str.size(); }
 
-  std::size_t size() const {
-    return d_str.size();
-  }
+  unsigned char getFirstChar() const { return getUnsignedCharAt(0); }
+  unsigned char getLastChar() const { return getUnsignedCharAt(size() - 1); }
 
-  unsigned char getFirstChar() const {
-    return convertUnsignedIntToChar( d_str[0] );
-  }
+  bool isRepeated() const;
+  bool tailcmp(const String& y, int& c) const;
 
-  unsigned char getLastChar() const {
-    assert(d_str.size() != 0);
-    return convertUnsignedIntToChar( d_str[d_str.size() - 1] );
-  }
+  std::size_t find(const String& y, const std::size_t start = 0) const;
+  std::size_t rfind(const String& y, const std::size_t start = 0) const;
 
-  bool isRepeated() const {
-  if(d_str.size() > 1) {
-    unsigned int f = d_str[0];
-    for(unsigned i=1; i<d_str.size(); ++i) {
-      if(f != d_str[i]) return false;
-    }
-  }
-  return true;
-  }
+  String replace(const String& s, const String& t) const;
+  String substr(std::size_t i) const;
+  String substr(std::size_t i, std::size_t j) const;
 
-  bool tailcmp(const String &y, int &c) const {
-    int id_x = d_str.size() - 1;
-    int id_y = y.d_str.size() - 1;
-    while(id_x>=0 && id_y>=0) {
-      if(d_str[id_x] != y.d_str[id_y]) {
-        c = id_x;
-        return false;
-      }
-      --id_x; --id_y;
-    }
-    c = id_x == -1 ? ( - (id_y+1) ) : (id_x + 1);
-    return true;
-  }
+  String prefix(std::size_t i) const { return substr(0, i); }
+  String suffix(std::size_t i) const { return substr(size() - i, i); }
+  // if y=y1...yn and overlap returns m, then this is x1...y1...ym
+  std::size_t overlap(const String& y) const;
+  // if y=y1...yn and overlap returns m, then this is y(n+1-m)...yn...xk
+  std::size_t roverlap(const String& y) const;
 
-  std::size_t find(const String &y, const std::size_t start = 0) const {
-    if(d_str.size() < y.d_str.size() + start) return std::string::npos;
-    if(y.d_str.size() == 0) return start;
-    if(d_str.size() == 0) return std::string::npos;
-    std::vector<unsigned>::const_iterator itr = std::search(d_str.begin() + start, d_str.end(), y.d_str.begin(), y.d_str.end());
-    if(itr != d_str.end()) {
-      return itr - d_str.begin();
-    }else{
-      return std::string::npos;
-    }
-  }
-  
-  std::size_t rfind( String &y, const std::size_t start = 0) {
-    std::reverse( d_str.begin(), d_str.end() );
-    std::reverse( y.d_str.begin(), y.d_str.end() );
-    std::size_t f = find( y, start );
-    std::reverse( d_str.begin(), d_str.end() );
-    std::reverse( y.d_str.begin(), y.d_str.end() );
-    if( f==std::string::npos ){
-      return std::string::npos;
-    }else{
-      return f;
-    }
-  }
+  bool isNumber() const;
+  int toNumber() const;
 
-  String replace(const String &s, const String &t) const {
-    std::size_t ret = find(s);
-    if( ret != std::string::npos ) {
-      std::vector<unsigned int> vec;
-      vec.insert(vec.begin(), d_str.begin(), d_str.begin() + ret);
-      vec.insert(vec.end(), t.d_str.begin(), t.d_str.end());
-      vec.insert(vec.end(), d_str.begin() + ret + s.d_str.size(), d_str.end());
-      return String(vec);
-    } else {
-      return *this;
-    }
-  }
+  const std::vector<unsigned>& getVec() const { return d_str; }
 
-  String substr(std::size_t i) const {
-    assert(i <= d_str.size());
-    std::vector<unsigned int> ret_vec;
-    std::vector<unsigned int>::const_iterator itr = d_str.begin() + i;
-    ret_vec.insert(ret_vec.end(), itr, d_str.end());
-    return String(ret_vec);
-  }
-  String substr(std::size_t i, std::size_t j) const {
-    assert(i+j <= d_str.size());
-    std::vector<unsigned int> ret_vec;
-    std::vector<unsigned int>::const_iterator itr = d_str.begin() + i;
-    ret_vec.insert( ret_vec.end(), itr, itr + j );
-    return String(ret_vec);
-  }
+ private:
+  // guarded
+  static unsigned char hexToDec(unsigned char c);
 
-  String prefix(std::size_t i) const {
-    return substr(0, i);
-  }
-  String suffix(std::size_t i) const {
-    return substr(d_str.size() - i, i);
-  }
-  // if y=y1...yn and overlap returns m, then this is x1...y1...ym
-  std::size_t overlap(String &y) const;
-  // if y=y1...yn and overlap returns m, then this is y(n+1-m)...yn...xk
-  std::size_t roverlap(String &y) const;
-
-  bool isNumber() const {
-   if(d_str.size() == 0) return false;
-   for(unsigned int i=0; i<d_str.size(); ++i) {
-     unsigned char c = convertUnsignedIntToChar( d_str[i] );
-     if(c<'0' || c>'9') {
-       return false;
-     }
-   }
-   return true;
-  }
-  int toNumber() const {
-   if(isNumber()) {
-     int ret=0;
-     for(unsigned int i=0; i<d_str.size(); ++i) {
-       unsigned char c = convertUnsignedIntToChar( d_str[i] );
-       ret = ret * 10 + (int)c - (int)'0';
-     }
-     return ret;
-   } else {
-     return -1;
-   }
-  }
+  static std::vector<unsigned> toInternal(const std::string& s);
+  unsigned char getUnsignedCharAt(size_t pos) const;
 
-  void getCharSet(std::set<unsigned char> &cset) const;
+  /**
+   * Returns a negative number if *this < y, 0 if *this and y are equal and a
+   * positive number if *this > y.
+   */
+  int cmp(const String& y) const;
 
-  std::vector<unsigned> getVec() const {
-    return d_str;
-  }
-};/* class String */
+  std::vector<unsigned> d_str;
+}; /* class String */
 
 namespace strings {
 
 struct CVC4_PUBLIC StringHashFunction {
   size_t operator()(const ::CVC4::String& s) const {
-    return __gnu_cxx::hash<const char*>()(s.toString().c_str());
+    return std::hash<std::string>()(s.toString());
   }
-};/* struct StringHashFunction */
+}; /* struct StringHashFunction */
 
-}/* CVC4::strings namespace */
+}  // namespace strings
 
-std::ostream& operator <<(std::ostream& os, const String& s) CVC4_PUBLIC;
+std::ostream& operator<<(std::ostream& os, const String& s) CVC4_PUBLIC;
 
 class CVC4_PUBLIC RegExp {
-protected:
-  int d_type;
-public:
+ public:
   RegExp() : d_type(1) {}
+  explicit RegExp(const int t) : d_type(t) {}
 
-  RegExp(const int t) : d_type(t) {}
-
-  ~RegExp() {}
-
-  bool operator ==(const RegExp& y) const {
-    return d_type == y.d_type ;
-  }
-
-  bool operator !=(const RegExp& y) const {
-    return d_type != y.d_type ;
-  }
-
-  bool operator <(const RegExp& y) const {
-    return d_type < y.d_type;
-  }
-
-  bool operator >(const RegExp& y) const {
-    return d_type > y.d_type ;
-  }
-
-  bool operator <=(const RegExp& y) const {
-    return d_type <= y.d_type;
-  }
-
-  bool operator >=(const RegExp& y) const {
-    return d_type >= y.d_type ;
-  }
+  bool operator==(const RegExp& y) const { return d_type == y.d_type; }
+  bool operator!=(const RegExp& y) const { return d_type != y.d_type; }
+  bool operator<(const RegExp& y) const { return d_type < y.d_type; }
+  bool operator>(const RegExp& y) const { return d_type > y.d_type; }
+  bool operator<=(const RegExp& y) const { return d_type <= y.d_type; }
+  bool operator>=(const RegExp& y) const { return d_type >= y.d_type; }
 
   int getType() const { return d_type; }
-};/* class RegExp */
+
+ private:
+  int d_type;
+}; /* class RegExp */
 
 /**
  * Hash function for the RegExp constants.
@@ -385,10 +155,10 @@ struct CVC4_PUBLIC RegExpHashFunction {
   inline size_t operator()(const RegExp& s) const {
     return (size_t)s.getType();
   }
-};/* struct RegExpHashFunction */
+}; /* struct RegExpHashFunction */
 
-std::ostream& operator <<(std::ostream& os, const RegExp& s) CVC4_PUBLIC;
+std::ostream& operator<<(std::ostream& os, const RegExp& s) CVC4_PUBLIC;
 
-}/* CVC4 namespace */
+}  // namespace CVC4
 
 #endif /* __CVC4__REGEXP_H */
-- 
2.30.2