/*
 * Copyright (C) 2004, 2007, 2008 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#include "config.h"

#if !USE(GOOGLEURL)

#include "KURL.h"

#include "CString.h"
#include "PlatformString.h"
#include "TextEncoding.h"
#include <wtf/StdLibExtras.h>

#if USE(ICU_UNICODE)
#include <unicode/uidna.h>
#elif USE(QT4_UNICODE)
#include <QUrl>
#endif

#include <stdio.h>

using namespace std;
using namespace WTF;

namespace WebCore {

typedef Vector<char, 512> CharBuffer;
typedef Vector<UChar, 512> UCharBuffer;

// FIXME: This file makes too much use of the + operator on String.
// We either have to optimize that operator so it doesn't involve
// so many allocations, or change this to use Vector<UChar> instead.

enum URLCharacterClasses {
    // alpha 
    SchemeFirstChar = 1 << 0,

    // ( alpha | digit | "+" | "-" | "." )
    SchemeChar = 1 << 1,

    // mark        = "-" | "_" | "." | "!" | "~" | "*" | "'" | "(" | ")"
    // unreserved  = alphanum | mark
    // ( unreserved | escaped | ";" | ":" | "&" | "=" | "+" | "$" | "," )
    UserInfoChar = 1 << 2,

    // alnum | "." | "-" | "%"
    // The above is what the specification says, but we are lenient to
    // match existing practice and also allow:
    // "_"
    HostnameChar = 1 << 3,

    // hexdigit | ":" | "%"
    IPv6Char = 1 << 4,

    // "#" | "?" | "/" | nul
    PathSegmentEndChar = 1 << 5,

    // not allowed in path
    BadChar = 1 << 6
};

static const char hexDigits[17] = "0123456789ABCDEF";

static const unsigned char characterClassTable[256] = {
    /* 0 nul */ PathSegmentEndChar,    /* 1 soh */ BadChar,
    /* 2 stx */ BadChar,    /* 3 etx */ BadChar,
    /* 4 eot */ BadChar,    /* 5 enq */ BadChar,    /* 6 ack */ BadChar,    /* 7 bel */ BadChar,
    /* 8 bs */ BadChar,     /* 9 ht */ BadChar,     /* 10 nl */ BadChar,    /* 11 vt */ BadChar,
    /* 12 np */ BadChar,    /* 13 cr */ BadChar,    /* 14 so */ BadChar,    /* 15 si */ BadChar,
    /* 16 dle */ BadChar,   /* 17 dc1 */ BadChar,   /* 18 dc2 */ BadChar,   /* 19 dc3 */ BadChar,
    /* 20 dc4 */ BadChar,   /* 21 nak */ BadChar,   /* 22 syn */ BadChar,   /* 23 etb */ BadChar,
    /* 24 can */ BadChar,   /* 25 em */ BadChar,    /* 26 sub */ BadChar,   /* 27 esc */ BadChar,
    /* 28 fs */ BadChar,    /* 29 gs */ BadChar,    /* 30 rs */ BadChar,    /* 31 us */ BadChar,
    /* 32 sp */ BadChar,    /* 33  ! */ UserInfoChar,
    /* 34  " */ BadChar,    /* 35  # */ PathSegmentEndChar | BadChar,
    /* 36  $ */ UserInfoChar,    /* 37  % */ UserInfoChar | HostnameChar | IPv6Char | BadChar,
    /* 38  & */ UserInfoChar,    /* 39  ' */ UserInfoChar,
    /* 40  ( */ UserInfoChar,    /* 41  ) */ UserInfoChar,
    /* 42  * */ UserInfoChar,    /* 43  + */ SchemeChar | UserInfoChar,
    /* 44  , */ UserInfoChar,
    /* 45  - */ SchemeChar | UserInfoChar | HostnameChar,
    /* 46  . */ SchemeChar | UserInfoChar | HostnameChar,
    /* 47  / */ PathSegmentEndChar,
    /* 48  0 */ SchemeChar | UserInfoChar | HostnameChar | IPv6Char, 
    /* 49  1 */ SchemeChar | UserInfoChar | HostnameChar | IPv6Char,    
    /* 50  2 */ SchemeChar | UserInfoChar | HostnameChar | IPv6Char, 
    /* 51  3 */ SchemeChar | UserInfoChar | HostnameChar | IPv6Char,
    /* 52  4 */ SchemeChar | UserInfoChar | HostnameChar | IPv6Char, 
    /* 53  5 */ SchemeChar | UserInfoChar | HostnameChar | IPv6Char,
    /* 54  6 */ SchemeChar | UserInfoChar | HostnameChar | IPv6Char, 
    /* 55  7 */ SchemeChar | UserInfoChar | HostnameChar | IPv6Char,
    /* 56  8 */ SchemeChar | UserInfoChar | HostnameChar | IPv6Char, 
    /* 57  9 */ SchemeChar | UserInfoChar | HostnameChar | IPv6Char,
    /* 58  : */ UserInfoChar | IPv6Char,    /* 59  ; */ UserInfoChar,
    /* 60  < */ BadChar,    /* 61  = */ UserInfoChar,
    /* 62  > */ BadChar,    /* 63  ? */ PathSegmentEndChar | BadChar,
    /* 64  @ */ 0,
    /* 65  A */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar | IPv6Char,    
    /* 66  B */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar | IPv6Char,
    /* 67  C */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar | IPv6Char,
    /* 68  D */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar | IPv6Char,
    /* 69  E */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar | IPv6Char,
    /* 70  F */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar | IPv6Char,
    /* 71  G */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 72  H */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 73  I */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 74  J */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 75  K */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 76  L */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 77  M */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 78  N */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 79  O */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 80  P */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 81  Q */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 82  R */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 83  S */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 84  T */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 85  U */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 86  V */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 87  W */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 88  X */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar, 
    /* 89  Y */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 90  Z */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 91  [ */ 0,
    /* 92  \ */ 0,    /* 93  ] */ 0,
    /* 94  ^ */ 0,
    /* 95  _ */ UserInfoChar | HostnameChar,
    /* 96  ` */ 0,
    /* 97  a */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar | IPv6Char,
    /* 98  b */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar | IPv6Char, 
    /* 99  c */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar | IPv6Char,
    /* 100  d */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar | IPv6Char, 
    /* 101  e */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar | IPv6Char,
    /* 102  f */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar | IPv6Char, 
    /* 103  g */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 104  h */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar, 
    /* 105  i */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 106  j */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar, 
    /* 107  k */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 108  l */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar, 
    /* 109  m */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 110  n */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar, 
    /* 111  o */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 112  p */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar, 
    /* 113  q */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 114  r */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar, 
    /* 115  s */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 116  t */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar, 
    /* 117  u */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 118  v */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar, 
    /* 119  w */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 120  x */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar, 
    /* 121  y */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar,
    /* 122  z */ SchemeFirstChar | SchemeChar | UserInfoChar | HostnameChar, 
    /* 123  { */ 0,
    /* 124  | */ 0,   /* 125  } */ 0,   /* 126  ~ */ UserInfoChar,   /* 127 del */ BadChar,
    /* 128 */ BadChar, /* 129 */ BadChar, /* 130 */ BadChar, /* 131 */ BadChar,
    /* 132 */ BadChar, /* 133 */ BadChar, /* 134 */ BadChar, /* 135 */ BadChar,
    /* 136 */ BadChar, /* 137 */ BadChar, /* 138 */ BadChar, /* 139 */ BadChar,
    /* 140 */ BadChar, /* 141 */ BadChar, /* 142 */ BadChar, /* 143 */ BadChar,
    /* 144 */ BadChar, /* 145 */ BadChar, /* 146 */ BadChar, /* 147 */ BadChar,
    /* 148 */ BadChar, /* 149 */ BadChar, /* 150 */ BadChar, /* 151 */ BadChar,
    /* 152 */ BadChar, /* 153 */ BadChar, /* 154 */ BadChar, /* 155 */ BadChar,
    /* 156 */ BadChar, /* 157 */ BadChar, /* 158 */ BadChar, /* 159 */ BadChar,
    /* 160 */ BadChar, /* 161 */ BadChar, /* 162 */ BadChar, /* 163 */ BadChar,
    /* 164 */ BadChar, /* 165 */ BadChar, /* 166 */ BadChar, /* 167 */ BadChar,
    /* 168 */ BadChar, /* 169 */ BadChar, /* 170 */ BadChar, /* 171 */ BadChar,
    /* 172 */ BadChar, /* 173 */ BadChar, /* 174 */ BadChar, /* 175 */ BadChar,
    /* 176 */ BadChar, /* 177 */ BadChar, /* 178 */ BadChar, /* 179 */ BadChar,
    /* 180 */ BadChar, /* 181 */ BadChar, /* 182 */ BadChar, /* 183 */ BadChar,
    /* 184 */ BadChar, /* 185 */ BadChar, /* 186 */ BadChar, /* 187 */ BadChar,
    /* 188 */ BadChar, /* 189 */ BadChar, /* 190 */ BadChar, /* 191 */ BadChar,
    /* 192 */ BadChar, /* 193 */ BadChar, /* 194 */ BadChar, /* 195 */ BadChar,
    /* 196 */ BadChar, /* 197 */ BadChar, /* 198 */ BadChar, /* 199 */ BadChar,
    /* 200 */ BadChar, /* 201 */ BadChar, /* 202 */ BadChar, /* 203 */ BadChar,
    /* 204 */ BadChar, /* 205 */ BadChar, /* 206 */ BadChar, /* 207 */ BadChar,
    /* 208 */ BadChar, /* 209 */ BadChar, /* 210 */ BadChar, /* 211 */ BadChar,
    /* 212 */ BadChar, /* 213 */ BadChar, /* 214 */ BadChar, /* 215 */ BadChar,
    /* 216 */ BadChar, /* 217 */ BadChar, /* 218 */ BadChar, /* 219 */ BadChar,
    /* 220 */ BadChar, /* 221 */ BadChar, /* 222 */ BadChar, /* 223 */ BadChar,
    /* 224 */ BadChar, /* 225 */ BadChar, /* 226 */ BadChar, /* 227 */ BadChar,
    /* 228 */ BadChar, /* 229 */ BadChar, /* 230 */ BadChar, /* 231 */ BadChar,
    /* 232 */ BadChar, /* 233 */ BadChar, /* 234 */ BadChar, /* 235 */ BadChar,
    /* 236 */ BadChar, /* 237 */ BadChar, /* 238 */ BadChar, /* 239 */ BadChar,
    /* 240 */ BadChar, /* 241 */ BadChar, /* 242 */ BadChar, /* 243 */ BadChar,
    /* 244 */ BadChar, /* 245 */ BadChar, /* 246 */ BadChar, /* 247 */ BadChar,
    /* 248 */ BadChar, /* 249 */ BadChar, /* 250 */ BadChar, /* 251 */ BadChar,
    /* 252 */ BadChar, /* 253 */ BadChar, /* 254 */ BadChar, /* 255 */ BadChar
};

static int copyPathRemovingDots(char* dst, const char* src, int srcStart, int srcEnd);
static void encodeRelativeString(const String& rel, const TextEncoding&, CharBuffer& ouput);
static String substituteBackslashes(const String&);

static inline bool isSchemeFirstChar(char c) { return characterClassTable[static_cast<unsigned char>(c)] & SchemeFirstChar; }
static inline bool isSchemeFirstChar(UChar c) { return c <= 0xff && (characterClassTable[c] & SchemeFirstChar); }
static inline bool isSchemeChar(char c) { return characterClassTable[static_cast<unsigned char>(c)] & SchemeChar; }
static inline bool isSchemeChar(UChar c) { return c <= 0xff && (characterClassTable[c] & SchemeChar); }
static inline bool isUserInfoChar(unsigned char c) { return characterClassTable[c] & UserInfoChar; }
static inline bool isHostnameChar(unsigned char c) { return characterClassTable[c] & HostnameChar; }
static inline bool isIPv6Char(unsigned char c) { return characterClassTable[c] & IPv6Char; }
static inline bool isPathSegmentEndChar(char c) { return characterClassTable[static_cast<unsigned char>(c)] & PathSegmentEndChar; }
static inline bool isPathSegmentEndChar(UChar c) { return c <= 0xff && (characterClassTable[c] & PathSegmentEndChar); }
static inline bool isBadChar(unsigned char c) { return characterClassTable[c] & BadChar; }

static inline int hexDigitValue(UChar c)
{
    ASSERT(isASCIIHexDigit(c));
    if (c < 'A')
        return c - '0';
    return (c - 'A' + 10) & 0xF; // handle both upper and lower case without a branch
}

// Copies the source to the destination, assuming all the source characters are
// ASCII. The destination buffer must be large enough. Null characters are allowed
// in the source string, and no attempt is made to null-terminate the result.
static void copyASCII(const UChar* src, int length, char* dest)
{
    for (int i = 0; i < length; i++)
        dest[i] = static_cast<char>(src[i]);
}

static void appendASCII(const String& base, const char* rel, size_t len, CharBuffer& buffer)
{
    buffer.resize(base.length() + len + 1);
    copyASCII(base.characters(), base.length(), buffer.data());
    memcpy(buffer.data() + base.length(), rel, len);
    buffer[buffer.size() - 1] = '\0';
}

// FIXME: Move to PlatformString.h eventually.
// Returns the index of the first index in string |s| of any of the characters
// in |toFind|. |toFind| should be a null-terminated string, all characters up
// to the null will be searched. Returns int if not found.
static int findFirstOf(const UChar* s, int sLen, int startPos, const char* toFind)
{
    for (int i = startPos; i < sLen; i++) {
        const char* cur = toFind;
        while (*cur) {
            if (s[i] == *(cur++))
                return i;
        }
    }
    return -1;
}

#ifndef NDEBUG
static void checkEncodedString(const String& url)
{
    for (unsigned i = 0; i < url.length(); ++i)
        ASSERT(!(url[i] & ~0x7F));

    ASSERT(!url.length() || isSchemeFirstChar(url[0]));
}
#else
static inline void checkEncodedString(const String&)
{
}
#endif

inline bool KURL::protocolIs(const String& string, const char* protocol)
{
    return WebCore::protocolIs(string, protocol);
}

void KURL::invalidate()
{
    m_isValid = false;
    m_protocolInHTTPFamily = false;
    m_schemeEnd = 0;
    m_userStart = 0;
    m_userEnd = 0;
    m_passwordEnd = 0;
    m_hostEnd = 0;
    m_portEnd = 0;
    m_pathEnd = 0;
    m_pathAfterLastSlash = 0;
    m_queryEnd = 0;
    m_fragmentEnd = 0;
}

KURL::KURL(ParsedURLStringTag, const char* url)
{
    parse(url, 0);
    ASSERT(url == m_string);
}

KURL::KURL(ParsedURLStringTag, const String& url)
{
    parse(url);
    ASSERT(url == m_string);
}

KURL::KURL(const KURL& base, const String& relative)
{
    init(base, relative, UTF8Encoding());
}

KURL::KURL(const KURL& base, const String& relative, const TextEncoding& encoding)
{
    // For UTF-{7,16,32}, we want to use UTF-8 for the query part as 
    // we do when submitting a form. A form with GET method
    // has its contents added to a URL as query params and it makes sense
    // to be consistent.
    init(base, relative, encoding.encodingForFormSubmission());
}

void KURL::init(const KURL& base, const String& relative, const TextEncoding& encoding)
{
    // Allow resolutions with a null or empty base URL, but not with any other invalid one.
    // FIXME: Is this a good rule?
    if (!base.m_isValid && !base.isEmpty()) {
        m_string = relative;
        invalidate();
        return;
    }

    // For compatibility with Win IE, treat backslashes as if they were slashes,
    // as long as we're not dealing with javascript: or data: URLs.
    String rel = relative;
    if (rel.contains('\\') && !(protocolIsJavaScript(rel) || protocolIs(rel, "data")))
        rel = substituteBackslashes(rel);

    String* originalString = &rel;

    bool allASCII = charactersAreAllASCII(rel.characters(), rel.length());
    CharBuffer strBuffer;
    char* str;
    size_t len;
    if (allASCII) {
        len = rel.length();
        strBuffer.resize(len + 1);
        copyASCII(rel.characters(), len, strBuffer.data());
        strBuffer[len] = 0;
        str = strBuffer.data();
    } else {
        originalString = 0;
        encodeRelativeString(rel, encoding, strBuffer);
        str = strBuffer.data();
        len = strlen(str);
    }

    // Get rid of leading whitespace.
    while (*str == ' ') {
        originalString = 0;
        str++;
        --len;
    }

    // Get rid of trailing whitespace.
    while (len && str[len - 1] == ' ') {
        originalString = 0;
        str[--len] = '\0';
    }

    // According to the RFC, the reference should be interpreted as an
    // absolute URI if possible, using the "leftmost, longest"
    // algorithm. If the URI reference is absolute it will have a
    // scheme, meaning that it will have a colon before the first
    // non-scheme element.
    bool absolute = false;
    char* p = str;
    if (isSchemeFirstChar(*p)) {
        ++p;
        while (isSchemeChar(*p)) {
            ++p;
        }
        if (*p == ':') {
            if (p[1] != '/' && equalIgnoringCase(base.protocol(), String(str, p - str)) && base.isHierarchical()) {
                str = p + 1;
                originalString = 0;
            } else
                absolute = true;
        }
    }

    CharBuffer parseBuffer;

    if (absolute) {
        parse(str, originalString);
    } else {
        // If the base is empty or opaque (e.g. data: or javascript:), then the URL is invalid
        // unless the relative URL is a single fragment.
        if (!base.isHierarchical()) {
            if (str[0] == '#') {
                appendASCII(base.m_string.left(base.m_queryEnd), str, len, parseBuffer);
                parse(parseBuffer.data(), 0);
            } else {
                m_string = relative;
                invalidate();
            }
            return;
        }

        switch (str[0]) {
        case '\0':
            // the reference must be empty - the RFC says this is a
            // reference to the same document
            *this = base;
            break;
        case '#': {
            // must be fragment-only reference
            appendASCII(base.m_string.left(base.m_queryEnd), str, len, parseBuffer);
            parse(parseBuffer.data(), 0);
            break;
        }
        case '?': {
            // query-only reference, special case needed for non-URL results
            appendASCII(base.m_string.left(base.m_pathEnd), str, len, parseBuffer);
            parse(parseBuffer.data(), 0);
            break;
        }
        case '/':
            // must be net-path or absolute-path reference
            if (str[1] == '/') {
                // net-path
                appendASCII(base.m_string.left(base.m_schemeEnd + 1), str, len, parseBuffer);
                parse(parseBuffer.data(), 0);
            } else {
                // abs-path
                appendASCII(base.m_string.left(base.m_portEnd), str, len, parseBuffer);
                parse(parseBuffer.data(), 0);
            }
            break;
        default:
            {
                // must be relative-path reference

                // Base part plus relative part plus one possible slash added in between plus terminating \0 byte.
                parseBuffer.resize(base.m_pathEnd + 1 + len + 1);

                char* bufferPos = parseBuffer.data();

                // first copy everything before the path from the base
                unsigned baseLength = base.m_string.length();
                const UChar* baseCharacters = base.m_string.characters();
                CharBuffer baseStringBuffer(baseLength);
                copyASCII(baseCharacters, baseLength, baseStringBuffer.data());
                const char* baseString = baseStringBuffer.data();
                const char* baseStringStart = baseString;
                const char* pathStart = baseStringStart + base.m_portEnd;
                while (baseStringStart < pathStart)
                    *bufferPos++ = *baseStringStart++;
                char* bufferPathStart = bufferPos;

                // now copy the base path
                const char* baseStringEnd = baseString + base.m_pathEnd;

                // go back to the last slash
                while (baseStringEnd > baseStringStart && baseStringEnd[-1] != '/')
                    baseStringEnd--;

                if (baseStringEnd == baseStringStart) {
                    // no path in base, add a path separator if necessary
                    if (base.m_schemeEnd + 1 != base.m_pathEnd && *str && *str != '?' && *str != '#')
                        *bufferPos++ = '/';
                } else {
                    bufferPos += copyPathRemovingDots(bufferPos, baseStringStart, 0, baseStringEnd - baseStringStart);
                }

                const char* relStringStart = str;
                const char* relStringPos = relStringStart;

                while (*relStringPos && *relStringPos != '?' && *relStringPos != '#') {
                    if (relStringPos[0] == '.' && bufferPos[-1] == '/') {
                        if (isPathSegmentEndChar(relStringPos[1])) {
                            // skip over "." segment
                            relStringPos += 1;
                            if (relStringPos[0] == '/')
                                relStringPos++;
                            continue;
                        } else if (relStringPos[1] == '.' && isPathSegmentEndChar(relStringPos[2])) {
                            // skip over ".." segment and rewind the last segment
                            // the RFC leaves it up to the app to decide what to do with excess
                            // ".." segments - we choose to drop them since some web content
                            // relies on this.
                            relStringPos += 2;
                            if (relStringPos[0] == '/')
                                relStringPos++;
                            if (bufferPos > bufferPathStart + 1)
                                bufferPos--;
                            while (bufferPos > bufferPathStart + 1  && bufferPos[-1] != '/')
                                bufferPos--;
                            continue;
                        }
                    }

                    *bufferPos = *relStringPos;
                    relStringPos++;
                    bufferPos++;
                }

                // all done with the path work, now copy any remainder
                // of the relative reference; this will also add a null terminator
                strcpy(bufferPos, relStringPos);

                parse(parseBuffer.data(), 0);

                ASSERT(strlen(parseBuffer.data()) + 1 <= parseBuffer.size());
                break;
            }
        }
    }
}

KURL KURL::copy() const
{
    KURL result = *this;
    result.m_string = result.m_string.crossThreadString();
    return result;
}

bool KURL::hasPath() const
{
    return m_pathEnd != m_portEnd;
}

String KURL::lastPathComponent() const
{
    if (!hasPath())
        return String();

    int end = m_pathEnd - 1;
    if (m_string[end] == '/')
        --end;

    int start = m_string.reverseFind('/', end);
    if (start < m_portEnd)
        return String();
    ++start;

    return m_string.substring(start, end - start + 1);
}

String KURL::protocol() const
{
    return m_string.left(m_schemeEnd);
}

String KURL::host() const
{
    int start = hostStart();
    return decodeURLEscapeSequences(m_string.substring(start, m_hostEnd - start));
}

unsigned short KURL::port() const
{
    if (m_hostEnd == m_portEnd)
        return 0;

    int number = m_string.substring(m_hostEnd + 1, m_portEnd - m_hostEnd - 1).toInt();
    if (number < 0 || number > 0xFFFF)
        return 0;
    return number;
}

String KURL::pass() const
{
    if (m_passwordEnd == m_userEnd)
        return String();

    return decodeURLEscapeSequences(m_string.substring(m_userEnd + 1, m_passwordEnd - m_userEnd - 1)); 
}

String KURL::user() const
{
    return decodeURLEscapeSequences(m_string.substring(m_userStart, m_userEnd - m_userStart));
}

String KURL::fragmentIdentifier() const
{
    if (m_fragmentEnd == m_queryEnd)
        return String();

    return m_string.substring(m_queryEnd + 1, m_fragmentEnd - (m_queryEnd + 1));
}

bool KURL::hasFragmentIdentifier() const
{
    return m_fragmentEnd != m_queryEnd;
}

String KURL::baseAsString() const
{
    return m_string.left(m_pathAfterLastSlash);
}

#ifdef NDEBUG

static inline void assertProtocolIsGood(const char*)
{
}

#else

static void assertProtocolIsGood(const char* protocol)
{
    const char* p = protocol;
    while (*p) {
        ASSERT(*p > ' ' && *p < 0x7F && !(*p >= 'A' && *p <= 'Z'));
        ++p;
    }
}

#endif

bool KURL::protocolIs(const char* protocol) const
{
    assertProtocolIsGood(protocol);

    // JavaScript URLs are "valid" and should be executed even if KURL decides they are invalid.
    // The free function protocolIsJavaScript() should be used instead. 
    ASSERT(strcmp(protocol, "javascript") != 0);

    if (!m_isValid)
        return false;

    // Do the comparison without making a new string object.
    for (int i = 0; i < m_schemeEnd; ++i) {
        if (!protocol[i] || toASCIILower(m_string[i]) != protocol[i])
            return false;
    }
    return !protocol[m_schemeEnd]; // We should have consumed all characters in the argument.
}

String KURL::query() const
{
    if (m_queryEnd == m_pathEnd)
        return String();

    return m_string.substring(m_pathEnd + 1, m_queryEnd - (m_pathEnd + 1)); 
}

String KURL::path() const
{
    return decodeURLEscapeSequences(m_string.substring(m_portEnd, m_pathEnd - m_portEnd)); 
}

void KURL::setProtocol(const String& s)
{
    // FIXME: Non-ASCII characters must be encoded and escaped to match parse() expectations,
    // and to avoid changing more than just the protocol.

    if (!m_isValid) {
        parse(s + ":" + m_string);
        return;
    }

    parse(s + m_string.substring(m_schemeEnd));
}

void KURL::setHost(const String& s)
{
    if (!m_isValid)
        return;

    // FIXME: Non-ASCII characters must be encoded and escaped to match parse() expectations,
    // and to avoid changing more than just the host.

    bool slashSlashNeeded = m_userStart == m_schemeEnd + 1;

    parse(m_string.left(hostStart()) + (slashSlashNeeded ? "//" : "") + s + m_string.substring(m_hostEnd));
}

void KURL::setPort(unsigned short i)
{
    if (!m_isValid)
        return;

    if (i) {
        bool colonNeeded = m_portEnd == m_hostEnd;
        int portStart = (colonNeeded ? m_hostEnd : m_hostEnd + 1);

        parse(m_string.left(portStart) + (colonNeeded ? ":" : "") + String::number(i) + m_string.substring(m_portEnd));
    } else
        parse(m_string.left(m_hostEnd) + m_string.substring(m_portEnd));
}

void KURL::setHostAndPort(const String& hostAndPort)
{
    if (!m_isValid)
        return;

    // FIXME: Non-ASCII characters must be encoded and escaped to match parse() expectations,
    // and to avoid changing more than just host and port.

    bool slashSlashNeeded = m_userStart == m_schemeEnd + 1;

    parse(m_string.left(hostStart()) + (slashSlashNeeded ? "//" : "") + hostAndPort + m_string.substring(m_portEnd));
}

void KURL::setUser(const String& user)
{
    if (!m_isValid)
        return;

    // FIXME: Non-ASCII characters must be encoded and escaped to match parse() expectations,
    // and to avoid changing more than just the user login.
    String u;
    int end = m_userEnd;
    if (!user.isEmpty()) {
        u = user;
        if (m_userStart == m_schemeEnd + 1)
            u = "//" + u;
        // Add '@' if we didn't have one before.
        if (end == m_hostEnd || (end == m_passwordEnd && m_string[end] != '@'))
            u.append('@');
    } else {
        // Remove '@' if we now have neither user nor password.
        if (m_userEnd == m_passwordEnd && end != m_hostEnd && m_string[end] == '@')
            end += 1;
    }
    parse(m_string.left(m_userStart) + u + m_string.substring(end));
}

void KURL::setPass(const String& password)
{
    if (!m_isValid)
        return;

    // FIXME: Non-ASCII characters must be encoded and escaped to match parse() expectations,
    // and to avoid changing more than just the user password.
    String p;
    int end = m_passwordEnd;
    if (!password.isEmpty()) {
        p = ":" + password + "@";
        if (m_userEnd == m_schemeEnd + 1)
            p = "//" + p;
        // Eat the existing '@' since we are going to add our own.
        if (end != m_hostEnd && m_string[end] == '@')
            end += 1;
    } else {
        // Remove '@' if we now have neither user nor password.
        if (m_userStart == m_userEnd && end != m_hostEnd && m_string[end] == '@')
            end += 1;
    }
    parse(m_string.left(m_userEnd) + p + m_string.substring(end));
}

void KURL::setFragmentIdentifier(const String& s)
{
    if (!m_isValid)
        return;

    // FIXME: Non-ASCII characters must be encoded and escaped to match parse() expectations.
    parse(m_string.left(m_queryEnd) + "#" + s);
}

void KURL::removeFragmentIdentifier()
{
    if (!m_isValid)
        return;
    parse(m_string.left(m_queryEnd));
}
    
void KURL::setQuery(const String& query)
{
    if (!m_isValid)
        return;

    // FIXME: '#' and non-ASCII characters must be encoded and escaped.
    // Usually, the query is encoded using document encoding, not UTF-8, but we don't have
    // access to the document in this function.
    if ((query.isEmpty() || query[0] != '?') && !query.isNull())
        parse(m_string.left(m_pathEnd) + "?" + query + m_string.substring(m_queryEnd));
    else
        parse(m_string.left(m_pathEnd) + query + m_string.substring(m_queryEnd));

}

void KURL::setPath(const String& s)
{
    if (!m_isValid)
        return;

    // FIXME: encodeWithURLEscapeSequences does not correctly escape '#' and '?', so fragment and query parts
    // may be inadvertently affected.
    parse(m_string.left(m_portEnd) + encodeWithURLEscapeSequences(s) + m_string.substring(m_pathEnd));
}

String KURL::prettyURL() const
{
    if (!m_isValid)
        return m_string;

    Vector<UChar> result;

    append(result, protocol());
    result.append(':');

    Vector<UChar> authority;

    if (m_hostEnd != m_passwordEnd) {
        if (m_userEnd != m_userStart) {
            append(authority, user());
            authority.append('@');
        }
        append(authority, host());
        if (port() != 0) {
            authority.append(':');
            append(authority, String::number(port()));
        }
    }

    if (!authority.isEmpty()) {
        result.append('/');
        result.append('/');
        result.append(authority);
    } else if (protocolIs("file")) {
        result.append('/');
        result.append('/');
    }

    append(result, path());

    if (m_pathEnd != m_queryEnd) {
        result.append('?');
        append(result, query());
    }

    if (m_fragmentEnd != m_queryEnd) {
        result.append('#');
        append(result, fragmentIdentifier());
    }

    return String::adopt(result);
}

String decodeURLEscapeSequences(const String& str)
{
    return decodeURLEscapeSequences(str, UTF8Encoding());
}

String decodeURLEscapeSequences(const String& str, const TextEncoding& encoding)
{
    Vector<UChar> result;

    CharBuffer buffer;

    int length = str.length();
    int decodedPosition = 0;
    int searchPosition = 0;
    int encodedRunPosition;
    while ((encodedRunPosition = str.find('%', searchPosition)) >= 0) {
        // Find the sequence of %-escape codes.
        int encodedRunEnd = encodedRunPosition;
        while (length - encodedRunEnd >= 3
                && str[encodedRunEnd] == '%'
                && isASCIIHexDigit(str[encodedRunEnd + 1])
                && isASCIIHexDigit(str[encodedRunEnd + 2]))
            encodedRunEnd += 3;
        if (encodedRunEnd == encodedRunPosition) {
            ++searchPosition;
            continue;
        }
        searchPosition = encodedRunEnd;

        // Decode the %-escapes into bytes.
        unsigned runLength = (encodedRunEnd - encodedRunPosition) / 3;
        buffer.resize(runLength);
        char* p = buffer.data();
        const UChar* q = str.characters() + encodedRunPosition;
        for (unsigned i = 0; i < runLength; ++i) {
            *p++ = (hexDigitValue(q[1]) << 4) | hexDigitValue(q[2]);
            q += 3;
        }

        // Decode the bytes into Unicode characters.
        String decoded = (encoding.isValid() ? encoding : UTF8Encoding()).decode(buffer.data(), p - buffer.data());
        if (decoded.isEmpty())
            continue;

        // Build up the string with what we just skipped and what we just decoded.
        result.append(str.characters() + decodedPosition, encodedRunPosition - decodedPosition);
        result.append(decoded.characters(), decoded.length());
        decodedPosition = encodedRunEnd;
    }

    result.append(str.characters() + decodedPosition, length - decodedPosition);

    return String::adopt(result);
}

bool KURL::isLocalFile() const
{
    // Including feed here might be a bad idea since drag and drop uses this check
    // and including feed would allow feeds to potentially let someone's blog
    // read the contents of the clipboard on a drag, even without a drop.
    // Likewise with using the FrameLoader::shouldTreatURLAsLocal() function.
    return protocolIs("file");
}

static void appendEscapingBadChars(char*& buffer, const char* strStart, size_t length)
{
    char* p = buffer;

    const char* str = strStart;
    const char* strEnd = strStart + length;
    while (str < strEnd) {
        unsigned char c = *str++;
        if (isBadChar(c)) {
            if (c == '%' || c == '?') {
                *p++ = c;
            } else if (c != 0x09 && c != 0x0a && c != 0x0d) {
                *p++ = '%';
                *p++ = hexDigits[c >> 4];
                *p++ = hexDigits[c & 0xF];
            }
        } else {
            *p++ = c;
        }
    }

    buffer = p;
}

// copy a path, accounting for "." and ".." segments
static int copyPathRemovingDots(char* dst, const char* src, int srcStart, int srcEnd)
{
    char* bufferPathStart = dst;

    // empty path is a special case, and need not have a leading slash
    if (srcStart != srcEnd) {
        const char* baseStringStart = src + srcStart;
        const char* baseStringEnd = src + srcEnd;
        const char* baseStringPos = baseStringStart;

        // this code is unprepared for paths that do not begin with a
        // slash and we should always have one in the source string
        ASSERT(baseStringPos[0] == '/');

        // copy the leading slash into the destination
        *dst = *baseStringPos;
        baseStringPos++;
        dst++;

        while (baseStringPos < baseStringEnd) {
            if (baseStringPos[0] == '.' && dst[-1] == '/') {
                if (baseStringPos[1] == '/' || baseStringPos + 1 == baseStringEnd) {
                    // skip over "." segment
                    baseStringPos += 2;
                    continue;
                } else if (baseStringPos[1] == '.' && (baseStringPos[2] == '/' ||
                                       baseStringPos + 2 == baseStringEnd)) {
                    // skip over ".." segment and rewind the last segment
                    // the RFC leaves it up to the app to decide what to do with excess
                    // ".." segments - we choose to drop them since some web content
                    // relies on this.
                    baseStringPos += 3;
                    if (dst > bufferPathStart + 1)
                        dst--;
                    // Note that these two while blocks differ subtly.
                    // The first helps to remove multiple adjoining slashes as we rewind.
                    // The +1 to bufferPathStart in the first while block prevents eating a leading slash
                    while (dst > bufferPathStart + 1 && dst[-1] == '/')
                        dst--;
                    while (dst > bufferPathStart && dst[-1] != '/')
                        dst--;
                    continue;
                }
            }

            *dst = *baseStringPos;
            baseStringPos++;
            dst++;
        }
    }
    *dst = '\0';
    return dst - bufferPathStart;
}

static inline bool hasSlashDotOrDotDot(const char* str)
{
    const unsigned char* p = reinterpret_cast<const unsigned char*>(str);
    if (!*p)
        return false;
    unsigned char pc = *p;
    while (unsigned char c = *++p) {
        if (c == '.' && (pc == '/' || pc == '.'))
            return true;
        pc = c;
    }
    return false;
}

static inline bool matchLetter(char c, char lowercaseLetter)
{
    return (c | 0x20) == lowercaseLetter;
}

void KURL::parse(const String& string)
{
    checkEncodedString(string);

    CharBuffer buffer(string.length() + 1);
    copyASCII(string.characters(), string.length(), buffer.data());
    buffer[string.length()] = '\0';
    parse(buffer.data(), &string);
}

void KURL::parse(const char* url, const String* originalString)
{
    if (!url || url[0] == '\0') {
        // valid URL must be non-empty
        m_string = originalString ? *originalString : url;
        invalidate();
        return;
    }

    if (!isSchemeFirstChar(url[0])) {
        // scheme must start with an alphabetic character
        m_string = originalString ? *originalString : url;
        invalidate();
        return;
    }

    int schemeEnd = 0;
    while (isSchemeChar(url[schemeEnd]))
        schemeEnd++;

    if (url[schemeEnd] != ':') {
        m_string = originalString ? *originalString : url;
        invalidate();
        return;
    }

    int userStart = schemeEnd + 1;
    int userEnd;
    int passwordStart;
    int passwordEnd;
    int hostStart;
    int hostEnd;
    int portStart;
    int portEnd;

    bool hierarchical = url[schemeEnd + 1] == '/';

    bool isFile = schemeEnd == 4
        && matchLetter(url[0], 'f')
        && matchLetter(url[1], 'i')
        && matchLetter(url[2], 'l')
        && matchLetter(url[3], 'e');

    m_protocolInHTTPFamily = matchLetter(url[0], 'h')
        && matchLetter(url[1], 't')
        && matchLetter(url[2], 't')
        && matchLetter(url[3], 'p')
        && (url[4] == ':' || (matchLetter(url[4], 's') && url[5] == ':'));

    if (hierarchical && url[schemeEnd + 2] == '/') {
        // The part after the scheme is either a net_path or an abs_path whose first path segment is empty.
        // Attempt to find an authority.

        // FIXME: Authority characters may be scanned twice, and it would be nice to be faster.
        userStart += 2;
        userEnd = userStart;

        int colonPos = 0;
        while (isUserInfoChar(url[userEnd])) {
            if (url[userEnd] == ':' && colonPos == 0)
                colonPos = userEnd;
            userEnd++;
        }

        if (url[userEnd] == '@') {
            // actual end of the userinfo, start on the host
            if (colonPos != 0) {
                passwordEnd = userEnd;
                userEnd = colonPos;
                passwordStart = colonPos + 1;
            } else
                passwordStart = passwordEnd = userEnd;

            hostStart = passwordEnd + 1;
        } else if (url[userEnd] == '[' || isPathSegmentEndChar(url[userEnd])) {
            // hit the end of the authority, must have been no user
            // or looks like an IPv6 hostname
            // either way, try to parse it as a hostname
            userEnd = userStart;
            passwordStart = passwordEnd = userEnd;
            hostStart = userStart;
        } else {
            // invalid character
            m_string = originalString ? *originalString : url;
            invalidate();
            return;
        }

        hostEnd = hostStart;

        // IPV6 IP address
        if (url[hostEnd] == '[') {
            hostEnd++;
            while (isIPv6Char(url[hostEnd]))
                hostEnd++;
            if (url[hostEnd] == ']')
                hostEnd++;
            else {
                // invalid character
                m_string = originalString ? *originalString : url;
                invalidate();
                return;
            }
        } else {
            while (isHostnameChar(url[hostEnd]))
                hostEnd++;
        }
        
        if (url[hostEnd] == ':') {
            portStart = portEnd = hostEnd + 1;
 
            // possible start of port
            portEnd = portStart;
            while (isASCIIDigit(url[portEnd]))
                portEnd++;
        } else
            portStart = portEnd = hostEnd;

        if (!isPathSegmentEndChar(url[portEnd])) {
            // invalid character
            m_string = originalString ? *originalString : url;
            invalidate();
            return;
        }

        if (userStart == portEnd && !m_protocolInHTTPFamily && !isFile) {
            // No authority found, which means that this is not a net_path, but rather an abs_path whose first two
            // path segments are empty. For file, http and https only, an empty authority is allowed.
            userStart -= 2;
            userEnd = userStart;
            passwordStart = userEnd;
            passwordEnd = passwordStart;
            hostStart = passwordEnd;
            hostEnd = hostStart;
            portStart = hostEnd;
            portEnd = hostEnd;
        }
    } else {
        // the part after the scheme must be an opaque_part or an abs_path
        userEnd = userStart;
        passwordStart = passwordEnd = userEnd;
        hostStart = hostEnd = passwordEnd;
        portStart = portEnd = hostEnd;
    }

    int pathStart = portEnd;
    int pathEnd = pathStart;
    while (url[pathEnd] && url[pathEnd] != '?' && url[pathEnd] != '#')
        pathEnd++;

    int queryStart = pathEnd;
    int queryEnd = queryStart;
    if (url[queryStart] == '?') {
        while (url[queryEnd] && url[queryEnd] != '#')
            queryEnd++;
    }

    int fragmentStart = queryEnd;
    int fragmentEnd = fragmentStart;
    if (url[fragmentStart] == '#') {
        fragmentStart++;
        fragmentEnd = fragmentStart;
        while (url[fragmentEnd])
            fragmentEnd++;
    }

    // assemble it all, remembering the real ranges

    Vector<char, 4096> buffer(fragmentEnd * 3 + 1);

    char *p = buffer.data();
    const char *strPtr = url;

    // copy in the scheme
    const char *schemeEndPtr = url + schemeEnd;
    while (strPtr < schemeEndPtr)
        *p++ = *strPtr++;
    m_schemeEnd = p - buffer.data();

    bool hostIsLocalHost = portEnd - userStart == 9
        && matchLetter(url[userStart], 'l')
        && matchLetter(url[userStart+1], 'o')
        && matchLetter(url[userStart+2], 'c')
        && matchLetter(url[userStart+3], 'a')
        && matchLetter(url[userStart+4], 'l')
        && matchLetter(url[userStart+5], 'h')
        && matchLetter(url[userStart+6], 'o')
        && matchLetter(url[userStart+7], 's')
        && matchLetter(url[userStart+8], 't');

    // File URLs need a host part unless it is just file:// or file://localhost
    bool degenFilePath = pathStart == pathEnd && (hostStart == hostEnd || hostIsLocalHost);

    bool haveNonHostAuthorityPart = userStart != userEnd || passwordStart != passwordEnd || portStart != portEnd;

    // add ":" after scheme
    *p++ = ':';

    // if we have at least one authority part or a file URL - add "//" and authority
    if (isFile ? !degenFilePath : (haveNonHostAuthorityPart || hostStart != hostEnd)) {
        *p++ = '/';
        *p++ = '/';

        m_userStart = p - buffer.data();

        // copy in the user
        strPtr = url + userStart;
        const char* userEndPtr = url + userEnd;
        while (strPtr < userEndPtr)
            *p++ = *strPtr++;
        m_userEnd = p - buffer.data();

        // copy in the password
        if (passwordEnd != passwordStart) {
            *p++ = ':';
            strPtr = url + passwordStart;
            const char* passwordEndPtr = url + passwordEnd;
            while (strPtr < passwordEndPtr)
                *p++ = *strPtr++;
        }
        m_passwordEnd = p - buffer.data();

        // If we had any user info, add "@"
        if (p - buffer.data() != m_userStart)
            *p++ = '@';

        // copy in the host, except in the case of a file URL with authority="localhost"
        if (!(isFile && hostIsLocalHost && !haveNonHostAuthorityPart)) {
            strPtr = url + hostStart;
            const char* hostEndPtr = url + hostEnd;
            while (strPtr < hostEndPtr)
                *p++ = *strPtr++;
        }
        m_hostEnd = p - buffer.data();

        // copy in the port
        if (hostEnd != portStart) {
            *p++ = ':';
            strPtr = url + portStart;
            const char *portEndPtr = url + portEnd;
            while (strPtr < portEndPtr)
                *p++ = *strPtr++;
        }
        m_portEnd = p - buffer.data();
    } else
        m_userStart = m_userEnd = m_passwordEnd = m_hostEnd = m_portEnd = p - buffer.data();

    // For canonicalization, ensure we have a '/' for no path.
    // Do this only for hierarchical URL with protocol http or https.
    if (m_protocolInHTTPFamily && hierarchical && pathEnd == pathStart)
        *p++ = '/';

    // add path, escaping bad characters
    if (!hierarchical || !hasSlashDotOrDotDot(url))
        appendEscapingBadChars(p, url + pathStart, pathEnd - pathStart);
    else {
        CharBuffer pathBuffer(pathEnd - pathStart + 1);
        size_t length = copyPathRemovingDots(pathBuffer.data(), url, pathStart, pathEnd);
        appendEscapingBadChars(p, pathBuffer.data(), length);
    }

    m_pathEnd = p - buffer.data();

    // Find the position after the last slash in the path, or
    // the position before the path if there are no slashes in it.
    int i;
    for (i = m_pathEnd; i > m_portEnd; --i) {
        if (buffer[i - 1] == '/')
            break;
    }
    m_pathAfterLastSlash = i;

    // add query, escaping bad characters
    appendEscapingBadChars(p, url + queryStart, queryEnd - queryStart);
    m_queryEnd = p - buffer.data();

    // add fragment, escaping bad characters
    if (fragmentEnd != queryEnd) {
        *p++ = '#';
        appendEscapingBadChars(p, url + fragmentStart, fragmentEnd - fragmentStart);
    }
    m_fragmentEnd = p - buffer.data();

    ASSERT(p - buffer.data() <= static_cast<int>(buffer.size()));

    // If we didn't end up actually changing the original string and
    // it was already in a String, reuse it to avoid extra allocation.
    if (originalString && originalString->length() == static_cast<unsigned>(m_fragmentEnd) && strncmp(buffer.data(), url, m_fragmentEnd) == 0)
        m_string = *originalString;
    else
        m_string = String(buffer.data(), m_fragmentEnd);

    m_isValid = true;
}

bool equalIgnoringFragmentIdentifier(const KURL& a, const KURL& b)
{
    if (a.m_queryEnd != b.m_queryEnd)
        return false;
    unsigned queryLength = a.m_queryEnd;
    for (unsigned i = 0; i < queryLength; ++i)
        if (a.string()[i] != b.string()[i])
            return false;
    return true;
}

bool protocolHostAndPortAreEqual(const KURL& a, const KURL& b)
{
    if (a.m_schemeEnd != b.m_schemeEnd)
        return false;
    int hostStartA = a.hostStart();
    int hostStartB = b.hostStart();
    if (a.m_hostEnd - hostStartA != b.m_hostEnd - hostStartB)
        return false;

    // Check the scheme
    for (int i = 0; i < a.m_schemeEnd; ++i)
        if (a.string()[i] != b.string()[i])
            return false;
    
    // And the host
    for (int i = hostStartA; i < a.m_hostEnd; ++i)
        if (a.string()[i] != b.string()[i])
            return false;
    
    if (a.port() != b.port())
        return false;

    return true;
}
    

String encodeWithURLEscapeSequences(const String& notEncodedString)
{
    CString asUTF8 = notEncodedString.utf8();

    CharBuffer buffer(asUTF8.length() * 3 + 1);
    char* p = buffer.data();

    const char* str = asUTF8.data();
    const char* strEnd = str + asUTF8.length();
    while (str < strEnd) {
        unsigned char c = *str++;
        if (isBadChar(c)) {
            *p++ = '%';
            *p++ = hexDigits[c >> 4];
            *p++ = hexDigits[c & 0xF];
        } else
            *p++ = c;
    }

    ASSERT(p - buffer.data() <= static_cast<int>(buffer.size()));

    return String(buffer.data(), p - buffer.data());
}

// Appends the punycoded hostname identified by the given string and length to
// the output buffer. The result will not be null terminated.
static void appendEncodedHostname(UCharBuffer& buffer, const UChar* str, unsigned strLen)
{
    // Needs to be big enough to hold an IDN-encoded name.
    // For host names bigger than this, we won't do IDN encoding, which is almost certainly OK.
    const unsigned hostnameBufferLength = 2048;

    if (strLen > hostnameBufferLength || charactersAreAllASCII(str, strLen)) {
        buffer.append(str, strLen);
        return;
    }

#if USE(ICU_UNICODE)
    UChar hostnameBuffer[hostnameBufferLength];
    UErrorCode error = U_ZERO_ERROR;
    int32_t numCharactersConverted = uidna_IDNToASCII(str, strLen, hostnameBuffer,
        hostnameBufferLength, UIDNA_ALLOW_UNASSIGNED, 0, &error);
    if (error == U_ZERO_ERROR)
        buffer.append(hostnameBuffer, numCharactersConverted);
#elif USE(QT4_UNICODE)
    QByteArray result = QUrl::toAce(String(str, strLen));
    buffer.append(result.constData(), result.length());
#endif
}

static void findHostnamesInMailToURL(const UChar* str, int strLen, Vector<pair<int, int> >& nameRanges)
{
    // In a mailto: URL, host names come after a '@' character and end with a '>' or ',' or '?' or end of string character.
    // Skip quoted strings so that characters in them don't confuse us.
    // When we find a '?' character, we are past the part of the URL that contains host names.

    nameRanges.clear();

    int p = 0;
    while (1) {
        // Find start of host name or of quoted string.
        int hostnameOrStringStart = findFirstOf(str, strLen, p, "\"@?");
        if (hostnameOrStringStart == -1)
            return;
        UChar c = str[hostnameOrStringStart];
        p = hostnameOrStringStart + 1;

        if (c == '?')
            return;

        if (c == '@') {
            // Find end of host name.
            int hostnameStart = p;
            int hostnameEnd = findFirstOf(str, strLen, p, ">,?");
            bool done;
            if (hostnameEnd == -1) {
                hostnameEnd = strLen;
                done = true;
            } else {
                p = hostnameEnd;
                done = false;
            }

            nameRanges.append(make_pair(hostnameStart, hostnameEnd));

            if (done)
                return;
        } else {
            // Skip quoted string.
            ASSERT(c == '"');
            while (1) {
                int escapedCharacterOrStringEnd = findFirstOf(str, strLen, p, "\"\\");
                if (escapedCharacterOrStringEnd == -1)
                    return;

                c = str[escapedCharacterOrStringEnd];
                p = escapedCharacterOrStringEnd + 1;

                // If we are the end of the string, then break from the string loop back to the host name loop.
                if (c == '"')
                    break;

                // Skip escaped character.
                ASSERT(c == '\\');
                if (p == strLen)
                    return;

                ++p;
            }
        }
    }
}

static bool findHostnameInHierarchicalURL(const UChar* str, int strLen, int& startOffset, int& endOffset)
{
    // Find the host name in a hierarchical URL.
    // It comes after a "://" sequence, with scheme characters preceding, and
    // this should be the first colon in the string.
    // It ends with the end of the string or a ":" or a path segment ending character.
    // If there is a "@" character, the host part is just the part after the "@".
    int separator = findFirstOf(str, strLen, 0, ":");
    if (separator == -1 || separator + 2 >= strLen ||
        str[separator + 1] != '/' || str[separator + 2] != '/')
        return false;

    // Check that all characters before the :// are valid scheme characters.
    if (!isSchemeFirstChar(str[0]))
        return false;
    for (int i = 1; i < separator; ++i) {
        if (!isSchemeChar(str[i]))
            return false;
    }

    // Start after the separator.
    int authorityStart = separator + 3;

    // Find terminating character.
    int hostnameEnd = strLen;
    for (int i = authorityStart; i < strLen; ++i) {
        UChar c = str[i];
        if (c == ':' || (isPathSegmentEndChar(c) && c != 0)) {
            hostnameEnd = i;
            break;
        }
    }

    // Find "@" for the start of the host name.
    int userInfoTerminator = findFirstOf(str, strLen, authorityStart, "@");
    int hostnameStart;
    if (userInfoTerminator == -1 || userInfoTerminator > hostnameEnd)
        hostnameStart = authorityStart;
    else
        hostnameStart = userInfoTerminator + 1;

    startOffset = hostnameStart;
    endOffset = hostnameEnd;
    return true;
}

// Converts all hostnames found in the given input to punycode, preserving the
// rest of the URL unchanged. The output will NOT be null-terminated.
static void encodeHostnames(const String& str, UCharBuffer& output)
{
    output.clear();

    if (protocolIs(str, "mailto")) {
        Vector<pair<int, int> > hostnameRanges;
        findHostnamesInMailToURL(str.characters(), str.length(), hostnameRanges);
        int n = hostnameRanges.size();
        int p = 0;
        for (int i = 0; i < n; ++i) {
            const pair<int, int>& r = hostnameRanges[i];
            output.append(&str.characters()[p], r.first - p);
            appendEncodedHostname(output, &str.characters()[r.first], r.second - r.first);
            p = r.second;
        }
        // This will copy either everything after the last hostname, or the
        // whole thing if there is no hostname.
        output.append(&str.characters()[p], str.length() - p);
    } else {
        int hostStart, hostEnd;
        if (findHostnameInHierarchicalURL(str.characters(), str.length(), hostStart, hostEnd)) {
            output.append(str.characters(), hostStart); // Before hostname.
            appendEncodedHostname(output, &str.characters()[hostStart], hostEnd - hostStart);
            output.append(&str.characters()[hostEnd], str.length() - hostEnd); // After hostname.
        } else {
            // No hostname to encode, return the input.
            output.append(str.characters(), str.length());
        }
    }
}

static void encodeRelativeString(const String& rel, const TextEncoding& encoding, CharBuffer& output)
{
    UCharBuffer s;
    encodeHostnames(rel, s);

    TextEncoding pathEncoding(UTF8Encoding()); // Path is always encoded as UTF-8; other parts may depend on the scheme.

    int pathEnd = -1;
    if (encoding != pathEncoding && encoding.isValid() && !protocolIs(rel, "mailto") && !protocolIs(rel, "data") && !protocolIsJavaScript(rel)) {
        // Find the first instance of either # or ?, keep pathEnd at -1 otherwise.
        pathEnd = findFirstOf(s.data(), s.size(), 0, "#?");
    }

    if (pathEnd == -1) {
        CString decoded = pathEncoding.encode(s.data(), s.size(), URLEncodedEntitiesForUnencodables);
        output.resize(decoded.length());
        memcpy(output.data(), decoded.data(), decoded.length());
    } else {
        CString pathDecoded = pathEncoding.encode(s.data(), pathEnd, URLEncodedEntitiesForUnencodables);
        // Unencodable characters in URLs are represented by converting
        // them to XML entities and escaping non-alphanumeric characters.
        CString otherDecoded = encoding.encode(s.data() + pathEnd, s.size() - pathEnd, URLEncodedEntitiesForUnencodables);

        output.resize(pathDecoded.length() + otherDecoded.length());
        memcpy(output.data(), pathDecoded.data(), pathDecoded.length());
        memcpy(output.data() + pathDecoded.length(), otherDecoded.data(), otherDecoded.length());
    }
    output.append('\0'); // null-terminate the output.
}

static String substituteBackslashes(const String& string)
{
    int questionPos = string.find('?');
    int hashPos = string.find('#');
    int pathEnd;

    if (hashPos >= 0 && (questionPos < 0 || questionPos > hashPos))
        pathEnd = hashPos;
    else if (questionPos >= 0)
        pathEnd = questionPos;
    else
        pathEnd = string.length();

    return string.left(pathEnd).replace('\\','/') + string.substring(pathEnd);
}

bool KURL::isHierarchical() const
{
    if (!m_isValid)
        return false;
    ASSERT(m_string[m_schemeEnd] == ':');
    return m_string[m_schemeEnd + 1] == '/';
}

void KURL::copyToBuffer(CharBuffer& buffer) const
{
    // FIXME: This throws away the high bytes of all the characters in the string!
    // That's fine for a valid URL, which is all ASCII, but not for invalid URLs.
    buffer.resize(m_string.length());
    copyASCII(m_string.characters(), m_string.length(), buffer.data());
}

bool protocolIs(const String& url, const char* protocol)
{
    // Do the comparison without making a new string object.
    assertProtocolIsGood(protocol);
    for (int i = 0; ; ++i) {
        if (!protocol[i])
            return url[i] == ':';
        if (toASCIILower(url[i]) != protocol[i])
            return false;
    }
}

bool protocolIsJavaScript(const String& url)
{
    return protocolIs(url, "javascript");
}

String mimeTypeFromDataURL(const String& url)
{
    ASSERT(protocolIs(url, "data"));
    int index = url.find(';');
    if (index == -1)
        index = url.find(',');
    if (index != -1) {
        int len = index - 5;
        if (len > 0)
            return url.substring(5, len);
        return "text/plain"; // Data URLs with no MIME type are considered text/plain.
    }
    return "";
}

const KURL& blankURL()
{
    DEFINE_STATIC_LOCAL(KURL, staticBlankURL, (ParsedURLString, "about:blank"));
    return staticBlankURL;
}

#ifndef NDEBUG
void KURL::print() const
{
    printf("%s\n", m_string.utf8().data());
}
#endif

}

#endif  // !USE(GOOGLEURL)
