gecko-dev/layout/style/ShadowParts.cpp

143 lines
3.9 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "ShadowParts.h"
#include "nsContentUtils.h"
#include "nsString.h"
namespace mozilla {
static bool IsSpace(char16_t aChar) {
return nsContentUtils::IsHTMLWhitespace(aChar);
};
using SingleMapping = std::pair<RefPtr<nsAtom>, RefPtr<nsAtom>>;
// https://drafts.csswg.org/css-shadow-parts/#parsing-mapping
//
// Returns null on both tokens to signal an error.
static SingleMapping ParseSingleMapping(const nsAString& aString) {
const char16_t* c = aString.BeginReading();
const char16_t* end = aString.EndReading();
const auto CollectASequenceOfSpaces = [&c, end]() {
while (c != end && IsSpace(*c)) {
++c;
}
};
const auto CollectToken = [&c, end]() -> RefPtr<nsAtom> {
const char16_t* t = c;
while (c != end && !IsSpace(*c) && *c != ':') {
++c;
}
if (c == t) {
return nullptr;
}
return NS_AtomizeMainThread(Substring(t, c));
};
// Steps 1 and 2 are variable declarations.
//
// 3. Collect a sequence of code points that are space characters.
CollectASequenceOfSpaces();
// 4. Collect a sequence of code points that are not space characters or
// U+003A COLON characters, and call the result first token.
RefPtr<nsAtom> firstToken = CollectToken();
// 5. If first token is empty then return error.
if (!firstToken) {
return {nullptr, nullptr};
}
// 6. Collect a sequence of code points that are space characters.
CollectASequenceOfSpaces();
// 7. If the end of the input has been reached, return the pair first
// token/first token.
if (c == end) {
return {firstToken, firstToken};
}
// 8. If character at position is not a U+003A COLON character, return error.
if (*c != ':') {
return {nullptr, nullptr};
}
// 9. Consume the U+003A COLON character.
++c;
// 10. Collect a sequence of code points that are space characters.
CollectASequenceOfSpaces();
// 11. Collect a sequence of code points that are not space characters or
// U+003A COLON characters. and let second token be the result.
RefPtr<nsAtom> secondToken = CollectToken();
// 12. If second token is empty then return error.
if (!secondToken) {
return {nullptr, nullptr};
}
// 13. Collect a sequence of code points that are space characters.
CollectASequenceOfSpaces();
// 14. If position is not past the end of input then return error.
if (c != end) {
return {nullptr, nullptr};
}
// 15. Return the pair first token/second token.
return {std::move(firstToken), std::move(secondToken)};
}
// https://drafts.csswg.org/css-shadow-parts/#parsing-mapping-list
ShadowParts ShadowParts::Parse(const nsAString& aString) {
ShadowParts parts;
for (const auto& substring : aString.Split(',')) {
auto mapping = ParseSingleMapping(substring);
if (!mapping.first) {
MOZ_ASSERT(!mapping.second);
continue;
}
nsAtom* second = mapping.second.get();
parts.mMappings.GetOrInsertNew(mapping.first)
->AppendElement(std::move(mapping.second));
parts.mReverseMappings.InsertOrUpdate(second, std::move(mapping.first));
}
return parts;
}
#ifdef DEBUG
void ShadowParts::Dump() const {
if (mMappings.IsEmpty()) {
printf(" (empty)\n");
return;
}
for (auto& entry : mMappings) {
nsAutoCString key;
entry.GetKey()->ToUTF8String(key);
printf(" %s: ", key.get());
bool first = true;
for (nsAtom* part : *entry.GetData()) {
if (!first) {
printf(", ");
}
first = false;
nsAutoCString value;
part->ToUTF8String(value);
printf("%s", value.get());
}
printf("\n");
}
}
#endif
} // namespace mozilla