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Diffstat (limited to 'src/mbgl/style/expression/match.cpp')
| -rw-r--r-- | src/mbgl/style/expression/match.cpp | 263 |
1 files changed, 263 insertions, 0 deletions
diff --git a/src/mbgl/style/expression/match.cpp b/src/mbgl/style/expression/match.cpp new file mode 100644 index 0000000000..35356747c9 --- /dev/null +++ b/src/mbgl/style/expression/match.cpp @@ -0,0 +1,263 @@ +#include <mbgl/style/expression/match.hpp> +#include <mbgl/style/expression/check_subtype.hpp> +#include <mbgl/style/expression/parsing_context.hpp> +#include <mbgl/util/string.hpp> + +namespace mbgl { +namespace style { +namespace expression { + +template <typename T> +void Match<T>::eachChild(const std::function<void(const Expression&)>& visit) const { + visit(*input); + for (const std::pair<T, std::shared_ptr<Expression>>& branch : branches) { + visit(*branch.second); + } + visit(*otherwise); +} + +template <typename T> +bool Match<T>::operator==(const Expression& e) const { + if (auto rhs = dynamic_cast<const Match*>(&e)) { + return (*input == *(rhs->input) && + *otherwise == *(rhs->otherwise) && + Expression::childrenEqual(branches, rhs->branches)); + } + return false; +} + + +template<> EvaluationResult Match<std::string>::evaluate(const EvaluationContext& params) const { + const EvaluationResult inputValue = input->evaluate(params); + if (!inputValue) { + return inputValue.error(); + } + + auto it = branches.find(inputValue->get<std::string>()); + if (it != branches.end()) { + return (*it).second->evaluate(params); + } + + return otherwise->evaluate(params); +} + +template<> EvaluationResult Match<int64_t>::evaluate(const EvaluationContext& params) const { + const EvaluationResult inputValue = input->evaluate(params); + if (!inputValue) { + return inputValue.error(); + } + + const auto numeric = inputValue->get<double>(); + int64_t rounded = std::floor(numeric); + if (numeric == rounded) { + auto it = branches.find(rounded); + if (it != branches.end()) { + return (*it).second->evaluate(params); + } + } + + return otherwise->evaluate(params); +} + +template class Match<int64_t>; +template class Match<std::string>; + +using InputType = variant<int64_t, std::string>; + +using namespace mbgl::style::conversion; +optional<InputType> parseInputValue(const Convertible& input, ParsingContext& parentContext, std::size_t index, optional<type::Type>& inputType) { + using namespace mbgl::style::conversion; + optional<InputType> result; + optional<type::Type> type; + + auto value = toValue(input); + + if (value) { + value->match( + [&] (uint64_t n) { + if (!Value::isSafeInteger(n)) { + parentContext.error("Branch labels must be integers no larger than " + util::toString(Value::maxSafeInteger()) + ".", index); + } else { + type = {type::Number}; + result = {static_cast<int64_t>(n)}; + } + }, + [&] (int64_t n) { + if (!Value::isSafeInteger(n)) { + parentContext.error("Branch labels must be integers no larger than " + util::toString(Value::maxSafeInteger()) + ".", index); + } else { + type = {type::Number}; + result = {n}; + } + }, + [&] (double n) { + if (!Value::isSafeInteger(n)) { + parentContext.error("Branch labels must be integers no larger than " + util::toString(Value::maxSafeInteger()) + ".", index); + } else if (n != std::floor(n)) { + parentContext.error("Numeric branch labels must be integer values.", index); + } else { + type = {type::Number}; + result = {static_cast<int64_t>(n)}; + } + }, + [&] (const std::string& s) { + type = {type::String}; + result = {s}; + }, + [&] (const auto&) { + parentContext.error("Branch labels must be numbers or strings.", index); + } + ); + } else { + parentContext.error("Branch labels must be numbers or strings.", index); + } + + if (!type) { + return result; + } + + if (!inputType) { + inputType = type; + } else { + optional<std::string> err = type::checkSubtype(*inputType, *type); + if (err) { + parentContext.error(*err, index); + return optional<InputType>(); + } + } + + return result; +} + +template <typename T> +static ParseResult create(type::Type outputType, + std::unique_ptr<Expression>input, + std::vector<std::pair<std::vector<InputType>, + std::unique_ptr<Expression>>> branches, + std::unique_ptr<Expression> otherwise, + ParsingContext& ctx) { + typename Match<T>::Branches typedBranches; + + std::size_t index = 2; + + typedBranches.reserve(branches.size()); + for (std::pair<std::vector<InputType>, + std::unique_ptr<Expression>>& pair : branches) { + std::shared_ptr<Expression> result = std::move(pair.second); + for (const InputType& label : pair.first) { + const auto& typedLabel = label.template get<T>(); + if (typedBranches.find(typedLabel) != typedBranches.end()) { + ctx.error("Branch labels must be unique.", index); + return ParseResult(); + } + typedBranches.emplace(typedLabel, result); + } + + index += 2; + } + return ParseResult(std::make_unique<Match<T>>( + outputType, + std::move(input), + std::move(typedBranches), + std::move(otherwise) + )); +} + +ParseResult parseMatch(const Convertible& value, ParsingContext& ctx) { + assert(isArray(value)); + auto length = arrayLength(value); + if (length < 5) { + ctx.error( + "Expected at least 4 arguments, but found only " + util::toString(length - 1) + "." + ); + return ParseResult(); + } + + // Expect odd-length array: ["match", input, 2 * (n pairs)..., otherwise] + if (length % 2 != 1) { + ctx.error("Expected an even number of arguments."); + return ParseResult(); + } + + optional<type::Type> inputType; + optional<type::Type> outputType; + if (ctx.getExpected() && *ctx.getExpected() != type::Value) { + outputType = ctx.getExpected(); + } + + std::vector<std::pair<std::vector<InputType>, + std::unique_ptr<Expression>>> branches; + + branches.reserve((length - 3) / 2); + for (size_t i = 2; i + 1 < length; i += 2) { + const auto& label = arrayMember(value, i); + + std::vector<InputType> labels; + // Match pair inputs are provided as either a literal value or a + // raw JSON array of string / number / boolean values. + if (isArray(label)) { + auto groupLength = arrayLength(label); + if (groupLength == 0) { + ctx.error("Expected at least one branch label.", i); + return ParseResult(); + } + + labels.reserve(groupLength); + for (size_t j = 0; j < groupLength; j++) { + const optional<InputType> inputValue = parseInputValue(arrayMember(label, j), ctx, i, inputType); + if (!inputValue) { + return ParseResult(); + } + labels.push_back(*inputValue); + } + } else { + const optional<InputType> inputValue = parseInputValue(label, ctx, i, inputType); + if (!inputValue) { + return ParseResult(); + } + labels.push_back(*inputValue); + } + + ParseResult output = ctx.parse(arrayMember(value, i + 1), i + 1, outputType); + if (!output) { + return ParseResult(); + } + + if (!outputType) { + outputType = (*output)->getType(); + } + + branches.push_back(std::make_pair(std::move(labels), std::move(*output))); + } + + auto input = ctx.parse(arrayMember(value, 1), 1, inputType); + if (!input) { + return ParseResult(); + } + + auto otherwise = ctx.parse(arrayMember(value, length - 1), length - 1, outputType); + if (!otherwise) { + return ParseResult(); + } + + assert(inputType && outputType); + + return inputType->match( + [&](const type::NumberType&) { + return create<int64_t>(*outputType, std::move(*input), std::move(branches), std::move(*otherwise), ctx); + }, + [&](const type::StringType&) { + return create<std::string>(*outputType, std::move(*input), std::move(branches), std::move(*otherwise), ctx); + }, + [&](const auto&) { + // unreachable: inputType is set by parseInputValue(), which only + // accepts string and (integer) numeric values. + assert(false); + return ParseResult(); + } + ); +} + +} // namespace expression +} // namespace style +} // namespace mbgl |