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#pragma once
#include <mbgl/style/expression/expression.hpp>
#include <mbgl/style/expression/parsing_context.hpp>
#include <mbgl/style/conversion.hpp>
namespace mbgl {
namespace style {
namespace expression {
class TypedCase : public TypedExpression {
public:
using Case = std::pair<std::unique_ptr<TypedExpression>, std::unique_ptr<TypedExpression>>;
TypedCase(std::vector<Case> cases_,
std::unique_ptr<TypedExpression> otherwise_
) : TypedExpression(otherwise_->getType()),
cases(std::move(cases_)),
otherwise(std::move(otherwise_))
{}
bool isFeatureConstant() const override {
if (!otherwise->isFeatureConstant()) { return false; }
for (const auto& pair : cases) {
if (!pair.first->isFeatureConstant() || !pair.second->isFeatureConstant()) {
return false;
}
}
return true;
}
bool isZoomConstant() const override {
if (!otherwise->isZoomConstant()) { return false; }
for (const auto& pair : cases) {
if (!pair.first->isFeatureConstant() || !pair.second->isZoomConstant()) {
return false;
}
}
return true;
}
EvaluationResult evaluate(const EvaluationParameters& params) const override {
for (const auto& casePair : cases) {
const auto& condition = casePair.first->template evaluate<bool>(params);
if (!condition) {
return condition.error();
}
if (*condition) {
return casePair.second->evaluate(params);
}
}
return otherwise->evaluate(params);
}
private:
std::unique_ptr<TypedExpression> input;
std::vector<Case> cases;
std::unique_ptr<TypedExpression> otherwise;
};
class UntypedCase : public UntypedExpression {
public:
using Cases = std::vector<std::pair<std::unique_ptr<UntypedExpression>, std::unique_ptr<UntypedExpression>>>;
UntypedCase(std::string key,
Cases cases_,
std::unique_ptr<UntypedExpression> otherwise_)
: UntypedExpression(key),
cases(std::move(cases_)),
otherwise(std::move(otherwise_))
{}
template <class V>
static ParseResult parse(const V& value, const ParsingContext& ctx) {
using namespace mbgl::style::conversion;
assert(isArray(value));
auto length = arrayLength(value);
if (length < 4) {
return CompileError {
"Expected at least 3 arguments, but found only " + std::to_string(length - 1) + ".",
ctx.key()
};
}
// Expect even-length array: ["case", 2 * (n pairs)..., otherwise]
if (length % 2 != 0) {
return CompileError {
"Missing final output value for \"case\" expression.",
ctx.key()
};
}
auto otherwise = parseExpression(arrayMember(value, length - 1), ParsingContext(ctx, {length - 1}, {"case"}));
if (otherwise.template is<CompileError>()) {
return otherwise;
}
Cases cases;
for (size_t i = 1; i + 1 < length; i += 2) {
auto condition = parseExpression(arrayMember(value, i), ParsingContext(ctx, {i}, {"case"}));
if (condition.template is<CompileError>()) {
return condition.template get<CompileError>();
}
auto output = parseExpression(arrayMember(value, i + 1), ParsingContext(ctx, {i + 1}, {"case"}));
if (output.template is<CompileError>()) {
return output.template get<CompileError>();
}
cases.push_back(std::make_pair(
std::move(condition.template get<std::unique_ptr<UntypedExpression>>()),
std::move(output.template get<std::unique_ptr<UntypedExpression>>()))
);
}
return std::make_unique<UntypedCase>(ctx.key(),
std::move(cases),
std::move(otherwise.template get<std::unique_ptr<UntypedExpression>>()));
}
TypecheckResult typecheck(std::vector<CompileError>& errors) const override {
auto checkedOtherwise = otherwise->typecheck(errors);
if (!checkedOtherwise) {
return TypecheckResult();
}
optional<type::Type> outputType;
std::vector<TypedCase::Case> checkedCases;
for (const auto& pair : cases) {
auto condition = pair.first->typecheck(errors);
if (!condition) continue;
auto error = matchType(type::Boolean, (*condition)->getType());
if (error) {
errors.push_back({ *error, pair.first->getKey() });
}
auto output = pair.second->typecheck(errors);
if (!output) continue;
if (!outputType) {
outputType = (*output)->getType();
} else {
error = matchType(*outputType, (*output)->getType());
if (error) {
errors.push_back({ *error, pair.second->getKey() });
}
}
if (errors.size() == 0) {
checkedCases.emplace_back(std::move(*condition), std::move(*output));
}
}
auto error = matchType(*outputType, (*checkedOtherwise)->getType());
if (error) {
errors.push_back({ *error, otherwise->getKey() });
}
if (errors.size() > 0) {
return TypecheckResult();
}
return TypecheckResult(std::make_unique<TypedCase>(std::move(checkedCases), std::move(*checkedOtherwise)));
};
private:
Cases cases;
std::unique_ptr<UntypedExpression> otherwise;
};
} // namespace expression
} // namespace style
} // namespace mbgl
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