Source/WebCore/css/CSSMarkup.cpp

/*
 * Copyright (C) 2003 Lars Knoll (knoll@kde.org)
 * Copyright (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
 * Copyright (C) 2004-2012, 2016 Apple Inc. All rights reserved.
 * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
 * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
 * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
 * Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved.
 * Copyright (C) 2012 Intel Corporation. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include "config.h"
#include "CSSMarkup.h"

#include "CSSParserIdioms.h"
#include "CSSPropertyParser.h"
#include <wtf/HexNumber.h>
#include <wtf/text/ParsingUtilities.h>
#include <wtf/text/StringBuilder.h>
#include <wtf/unicode/CharacterNames.h>

namespace WebCore {

template <typename CharacterType>
static inline bool NODELETE isCSSTokenizerIdentifier(std::span<const CharacterType> characters)
{
    // -?
    skipWhile(characters, '-');

    // {nmstart}
    if (!skipExactly<isNameStartCodePoint>(characters))
        return false;

    // {nmchar}*
    skipWhile<isNameCodePoint>(characters);

    return characters.empty();
}

// "ident" from the CSS tokenizer, minus backslash-escape sequences
static bool NODELETE isCSSTokenizerIdentifier(StringView string)
{
    if (string.isEmpty())
        return false;

    if (string.is8Bit())
        return isCSSTokenizerIdentifier(string.span8());
    return isCSSTokenizerIdentifier(string.span16());
}

// https://drafts.csswg.org/css-syntax-3/#non-printable-code-point
static bool isNonPrintableCodePoint(char32_t c)
{
    return c <= 0x08 || c == 0x0b || (c >= 0x0e && c <= 0x1f) || c == deleteCharacter;
}

static void serializeCharacter(StringBuilder& appendTo, char32_t c)
{
    appendTo.append('\\', c);
}

static void serializeCharacterAsEscapeSequence(StringBuilder& appendTo, char32_t c)
{
    appendTo.append('\\', hex(c, Lowercase), ' ');
}

void serializeIdentifier(StringBuilder& appendTo, StringView identifier, ShouldSkipStartChecks skipStartChecks)
{
    bool isFirst = skipStartChecks == ShouldSkipStartChecks::No;
    bool isSecond = false;
    bool isFirstCharHyphen = false;
    unsigned index = 0;
    while (index < identifier.length()) {
        char32_t c = identifier.codePointAt(index);

        index += U16_LENGTH(c);

        if (!c)
            appendTo.append(replacementCharacter);
        else if (c <= 0x1f || c == deleteCharacter || (0x30 <= c && c <= 0x39 && (isFirst || (isSecond && isFirstCharHyphen))))
            serializeCharacterAsEscapeSequence(appendTo, c);
        else if (c == hyphenMinus && isFirst && index == identifier.length())
            serializeCharacter(appendTo, c);
        else if (0x80 <= c || c == hyphenMinus || c == lowLine || (0x30 <= c && c <= 0x39) || (0x41 <= c && c <= 0x5a) || (0x61 <= c && c <= 0x7a))
            appendTo.append(c);
        else
            serializeCharacter(appendTo, c);

        if (isFirst) {
            isFirst = false;
            isSecond = true;
            isFirstCharHyphen = (c == hyphenMinus);
        } else if (isSecond)
            isSecond = false;
    }
}

void serializeString(StringBuilder& appendTo, StringView string)
{
    appendTo.append('"');

    unsigned index = 0;
    while (index < string.length()) {
        char32_t c = string.codePointAt(index);
        index += U16_LENGTH(c);

        if (c <= 0x1f || c == deleteCharacter)
            serializeCharacterAsEscapeSequence(appendTo, c);
        else if (c == quotationMark || c == reverseSolidus)
            serializeCharacter(appendTo, c);
        else
            appendTo.append(c);
    }

    appendTo.append('"');
}

// https://drafts.csswg.org/css-syntax-3/#consume-url-token
void serializeURLTokenValue(StringBuilder& appendTo, StringView string)
{
    for (auto c : string.codePoints()) {
        if (!c)
            appendTo.append(replacementCharacter);
        else if (isNonPrintableCodePoint(c) || isCSSNewline(c))
            serializeCharacterAsEscapeSequence(appendTo, c);
        else if (c == '"' || c == '\'' || c == '(' || c == ')' || c == reverseSolidus || isASCIIWhitespace(c))
            serializeCharacter(appendTo, c);
        else
            appendTo.append(c);
    }
}

String serializeString(StringView string)
{
    StringBuilder builder;
    serializeString(builder, string);
    return builder.toString();
}

static bool shouldQuoteFontFamily(StringView string)
{
    // Font family names that match CSS-wide keywords, 'default', or generic
    // family keywords must be quoted to prevent confusion with the keywords
    // of the same names.
    // https://www.w3.org/TR/css-fonts-4/#family-name-syntax
    //
    // FIXME: We also quote when the first word of a multi-word name is a
    // generic keyword, matching parser behavior. See webkit.org/b/314837.
    //
    // Note: system-ui is excluded from quoting because the parser always
    // stores it as a CSS_FONT_FAMILY string (not a CSSValueID), even when
    // used as a generic keyword. Since we cannot distinguish the generic
    // keyword from a quoted family name at this point, and the generic
    // keyword is the common case, we leave it unquoted.
    auto stringID = cssValueKeywordID(string);
    if (stringID == CSSValueSystemUi)
        return false;
    if (isGenericFontFamilyKeyword(stringID))
        return true;

    // Leading, trailing, or consecutive spaces are collapsed on re-parse,
    // so names containing them must be quoted to round-trip.
    if (string.startsWith(' ') || string.endsWith(' ') || string.contains("  "_s))
        return true;

    bool isFirstWord = true;
    bool hasWord = false;
    for (auto word : string.split(' ')) {
        if (!isCSSTokenizerIdentifier(word))
            return true;
        auto valueID = cssValueKeywordID(word);
        if (!isValidCustomIdentifier(valueID))
            return true;
        if (isFirstWord && isGenericFontFamilyKeyword(valueID))
            return true;
        hasWord = true;
        isFirstWord = false;
    }
    return !hasWord;
}

void serializeFontFamily(StringBuilder& builder, StringView string)
{
    if (shouldQuoteFontFamily(string)) {
        serializeString(builder, string);
        return;
    }

    builder.append(string);
}

String serializeFontFamily(const String& string)
{
    if (shouldQuoteFontFamily(string))
        return serializeString(string);
    return string;
}

} // namespace WebCore