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path: root/include/mbgl/style/expression/parse/literal.hpp
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#pragma once

#include <vector>
#include <memory>
#include <mbgl/util/optional.hpp>
#include <mbgl/style/expression/literal.hpp>
#include <mbgl/style/expression/type.hpp>
#include <mbgl/style/expression/value.hpp>
#include <mbgl/style/expression/parsing_context.hpp>
#include <mbgl/style/conversion.hpp>


namespace mbgl {
namespace style {
namespace expression {

struct ParseLiteral {
    static ParseResult parse(const mbgl::style::conversion::Value& value, ParsingContext ctx) {
        const optional<Value> parsedValue = parseValue(value, ctx);
        
        if (!parsedValue) {
            return ParseResult();
        }
        
        // special case: infer the item type if possible for zero-length arrays
        if (
            ctx.expected &&
            ctx.expected->template is<type::Array>() &&
            parsedValue->template is<std::vector<Value>>()
        ) {
            auto type = typeOf(*parsedValue).template get<type::Array>();
            auto expected = ctx.expected->template get<type::Array>();
            if (
                type.N && (*type.N == 0) &&
                (!expected.N || (*expected.N == 0))
            ) {
                return ParseResult(std::make_unique<Literal>(expected, parsedValue->template get<std::vector<Value>>()));
            }
        }
        return ParseResult(std::make_unique<Literal>(*parsedValue));
    }

    static optional<Value> parseValue(const mbgl::style::conversion::Value& value, ParsingContext ctx) {
        using namespace mbgl::style::conversion;
        if (isUndefined(value)) return {Null};
        if (isObject(value)) {
            std::unordered_map<std::string, Value> result;
            bool error = false;
            eachMember(value, [&] (const std::string& k, const mbgl::style::conversion::Value& v) -> optional<conversion::Error> {
                if (!error) {
                    optional<Value> memberValue = parseValue(v, ctx);
                    if (memberValue) {
                        result.emplace(k, *memberValue);
                    } else {
                        error = true;
                    }
                }
                return {};
            });
            return error ? optional<Value>() : optional<Value>(result);
        }
        
        if (isArray(value)) {
            std::vector<Value> result;
            const auto length = arrayLength(value);
            for(std::size_t i = 0; i < length; i++) {
                optional<Value> item = parseValue(arrayMember(value, i), ctx);
                if (item) {
                    result.emplace_back(*item);
                } else {
                    return optional<Value>();
                }
            }
            return optional<Value>(result);
        }
        
        optional<mbgl::Value> v = toValue(value);
        assert(v);
        
        return v->match(
            [&](uint64_t n) { return checkNumber(n); },
            [&](int64_t n) { return checkNumber(n); },
            [&](double n) { return checkNumber(n); },
            [&](const auto&) {
                return optional<Value>(toExpressionValue(*v));
            }
        );
    }
    
    template <typename T>
    static optional<Value> checkNumber(T n) {
        if (n > std::numeric_limits<double>::max()) {
            return {std::numeric_limits<double>::infinity()};
        } else {
            return {static_cast<double>(n)};
        }
    }
};

} // namespace expression
} // namespace style
} // namespace mbgl