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#include <mbgl/style/expression/coalesce.hpp>
#include <mbgl/style/expression/check_subtype.hpp>
namespace mbgl {
namespace style {
namespace expression {
EvaluationResult Coalesce::evaluate(const EvaluationContext& params) const {
EvaluationResult result = Null;
for (const auto& arg : args) {
result = arg->evaluate(params);
if (!result || *result != Null) break;
}
return result;
}
void Coalesce::eachChild(const std::function<void(const Expression&)>& visit) const {
for (const std::unique_ptr<Expression>& arg : args) {
visit(*arg);
}
}
bool Coalesce::operator==(const Expression& e) const {
if (auto rhs = dynamic_cast<const Coalesce*>(&e)) {
return Expression::childrenEqual(args, rhs->args);
}
return false;
}
using namespace mbgl::style::conversion;
ParseResult Coalesce::parse(const Convertible& value, ParsingContext& ctx) {
assert(isArray(value));
auto length = arrayLength(value);
if (length < 2) {
ctx.error("Expected at least one argument.");
return ParseResult();
}
optional<type::Type> outputType;
optional<type::Type> expectedType = ctx.getExpected();
if (expectedType && *expectedType != type::Value) {
outputType = expectedType;
}
Coalesce::Args args;
args.reserve(length - 1);
for (std::size_t i = 1; i < length; i++) {
auto parsed = ctx.parse(arrayMember(value, i), i, outputType, ParsingContext::omitTypeAnnotations);
if (!parsed) {
return parsed;
}
if (!outputType) {
outputType = (*parsed)->getType();
}
args.push_back(std::move(*parsed));
}
assert(outputType);
// Above, we parse arguments without inferred type annotation so that
// they don't produce a runtime error for `null` input, which would
// preempt the desired null-coalescing behavior.
// Thus, if any of our arguments would have needed an annotation, we
// need to wrap the enclosing coalesce expression with it instead.
bool needsAnnotation = expectedType &&
std::any_of(args.begin(), args.end(), [&] (const auto& arg) {
return type::checkSubtype(*expectedType, arg->getType());
});
return ParseResult(std::make_unique<Coalesce>(needsAnnotation ? type::Value : *outputType, std::move(args)));
}
} // namespace expression
} // namespace style
} // namespace mbgl
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