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Telegram/SourceFiles/lang/lang_text_entity.cpp

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+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#include "lang/lang_text_entity.h"
+
+#include "lang/lang_tag.h"
+
+namespace Lang {
+
+TextWithEntities ReplaceTag<TextWithEntities>::Call(TextWithEntities &&original, ushort tag, const TextWithEntities &replacement) {
+	auto replacementPosition = FindTagReplacementPosition(original.text, tag);
+	if (replacementPosition < 0) {
+		return std::move(original);
+	}
+	return Replace(std::move(original), replacement, replacementPosition);
+}
+
+TextWithEntities ReplaceTag<TextWithEntities>::Replace(TextWithEntities &&original, const TextWithEntities &replacement, int start) {
+	auto result = TextWithEntities();
+	result.text = ReplaceTag<QString>::Replace(std::move(original.text), replacement.text, start);
+	auto originalEntitiesCount = original.entities.size();
+	auto replacementEntitiesCount = replacement.entities.size();
+	if (originalEntitiesCount != 0 || replacementEntitiesCount != 0) {
+		result.entities.reserve(originalEntitiesCount + replacementEntitiesCount);
+
+		auto replacementEnd = start + int(replacement.text.size());
+		auto replacementEntity = replacement.entities.cbegin();
+		auto addReplacementEntitiesUntil = [&](int untilPosition) {
+			while (replacementEntity != replacement.entities.cend()) {
+				auto newOffset = start + replacementEntity->offset();
+				if (newOffset >= untilPosition) {
+					return;
+				}
+				auto newEnd = newOffset + replacementEntity->length();
+				newOffset = std::clamp(newOffset, start, replacementEnd);
+				newEnd = std::clamp(newEnd, start, replacementEnd);
+				if (auto newLength = newEnd - newOffset) {
+					result.entities.push_back({ replacementEntity->type(), newOffset, newLength, replacementEntity->data() });
+				}
+				++replacementEntity;
+			}
+		};
+
+		for (const auto &entity : std::as_const(original.entities)) {
+			// Transform the entity by the replacement.
+			auto offset = entity.offset();
+			auto end = offset + entity.length();
+			if (offset > start) {
+				offset = offset + replacement.text.size() - kTagReplacementSize;
+			}
+			if (end > start) {
+				end = end + replacement.text.size() - kTagReplacementSize;
+			}
+			offset = std::clamp(offset, 0, int(result.text.size()));
+			end = std::clamp(end, 0, int(result.text.size()));
+
+			// Add all replacement entities that start before the current original entity.
+			addReplacementEntitiesUntil(offset);
+
+			// Add a modified original entity.
+			if (auto length = end - offset) {
+				result.entities.push_back({ entity.type(), offset, length, entity.data() });
+			}
+		}
+		// Add the remaining replacement entities.
+		addReplacementEntitiesUntil(result.text.size());
+	}
+	return result;
+}
+
+} // namespace Lang