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#pragma once
#include <map>
#include <memory>
#include <mbgl/util/optional.hpp>
#include <mbgl/style/expression/curve.hpp>
#include <mbgl/style/expression/parsing_context.hpp>
#include <mbgl/style/conversion.hpp>
namespace mbgl {
namespace style {
namespace expression {
struct ParseCurve {
using Interpolator = variant<StepInterpolator,
ExponentialInterpolator,
CubicBezierInterpolator>;
template <typename V>
static ParseResult parse(const V& value, ParsingContext ctx) {
using namespace mbgl::style::conversion;
assert(isArray(value));
auto length = arrayLength(value);
// first parse interpolation, because further validation of the input depends upon
// whether or not this is a step curve
if (length < 2) {
ctx.error("Expected an interpolation type expression.");
return ParseResult();
}
const V& interp = arrayMember(value, 1);
if (!isArray(interp) || arrayLength(interp) == 0) {
ctx.error("Expected an interpolation type expression.");
return ParseResult();
}
Interpolator interpolator;
bool isStep = false;
const optional<std::string> interpName = toString(arrayMember(interp, 0));
ParsingContext interpContext = ParsingContext(ctx, 1);
if (interpName && *interpName == "step") {
interpolator = StepInterpolator();
isStep = true;
} else if (interpName && *interpName == "linear") {
interpolator = ExponentialInterpolator(1.0);
} else if (interpName && *interpName == "exponential") {
optional<double> base;
if (arrayLength(interp) == 2) {
base = toDouble(arrayMember(interp, 1));
}
if (!base) {
interpContext.error("Exponential interpolation requires a numeric base.", 1);
return ParseResult();
}
interpolator = ExponentialInterpolator(*base);
} else if (interpName && *interpName == "cubic-bezier") {
optional<double> x1;
optional<double> y1;
optional<double> x2;
optional<double> y2;
if (arrayLength(interp) == 5) {
x1 = toDouble(arrayMember(interp, 1));
y1 = toDouble(arrayMember(interp, 2));
x2 = toDouble(arrayMember(interp, 3));
y2 = toDouble(arrayMember(interp, 4));
}
if (
!x1 || !y1 || !x2 || !y2 ||
*x1 < 0 || *x1 > 1 ||
*y1 < 0 || *y1 > 1 ||
*x2 < 0 || *x2 > 1 ||
*y2 < 0 || *y2 > 1
) {
interpContext.error("Cubic bezier interpolation requires four numeric arguments with values between 0 and 1.");
return ParseResult();
}
interpolator = CubicBezierInterpolator(*x1, *y1, *x2, *y2);
} else {
interpContext.error("Unknown interpolation type " + (interpName ? *interpName : ""), 0);
return ParseResult();
}
std::size_t minArgs = isStep ? 5 : 4;
if (length - 1 < minArgs) {
ctx.error("Expected at least " + std::to_string(minArgs) + " arguments, but found only " + std::to_string(length - 1) + ".");
return ParseResult();
}
bool parity = minArgs % 2;
// [curve, interp, input, 2 * (n pairs)...]
if ((length - 1) % 2 != parity) {
ctx.error("Expected an " + std::string(parity ? "odd" : "even") + " number of arguments.");
return ParseResult();
}
ParseResult input = parseExpression(arrayMember(value, 2), ParsingContext(ctx, 2, {type::Number}));
if (!input) {
return input;
}
std::map<double, std::unique_ptr<Expression>> stops;
optional<type::Type> outputType;
if (ctx.expected && *ctx.expected != type::Value) {
outputType = ctx.expected;
}
double previous = - std::numeric_limits<double>::infinity();
// If this is a step curve, the definition begins with an output value rather
// than an input level, so consume that output value before proceeding into the
// "stops" loop below.
if (isStep) {
auto output = parseExpression(arrayMember(value, 3), ParsingContext(ctx, 3, outputType));
if (!output) {
return ParseResult();
}
if (!outputType) {
outputType = (*output)->getType();
}
stops.emplace(-std::numeric_limits<double>::infinity(), std::move(*output));
}
for (std::size_t i = isStep ? 4 : 3; i + 1 < length; i += 2) {
const optional<mbgl::Value> labelValue = toValue(arrayMember(value, i));
optional<double> label;
optional<std::string> labelError;
if (labelValue) {
labelValue->match(
[&](uint64_t n) {
if (n > std::numeric_limits<double>::max()) {
label = {std::numeric_limits<double>::infinity()};
} else {
label = {static_cast<double>(n)};
}
},
[&](int64_t n) {
if (n > std::numeric_limits<double>::max()) {
label = {std::numeric_limits<double>::infinity()};
} else {
label = {static_cast<double>(n)};
}
},
[&](double n) {
if (n > std::numeric_limits<double>::max()) {
label = {std::numeric_limits<double>::infinity()};
} else {
label = {static_cast<double>(n)};
}
},
[&](const auto&) {}
);
}
if (!label) {
ctx.error(labelError ? *labelError :
R"(Input/output pairs for "curve" expressions must be defined using literal numeric values (not computed expressions) for the input values.)",
i);
return ParseResult();
}
if (*label < previous) {
ctx.error(
R"(Input/output pairs for "curve" expressions must be arranged with input values in strictly ascending order.)",
i
);
return ParseResult();
}
previous = *label;
auto output = parseExpression(arrayMember(value, i + 1), ParsingContext(ctx, i + 1, outputType));
if (!output) {
return ParseResult();
}
if (!outputType) {
outputType = (*output)->getType();
}
stops.emplace(*label, std::move(*output));
}
assert(outputType);
if (
!interpolator.template is<StepInterpolator>() &&
*outputType != type::Number &&
*outputType != type::Color &&
!(
outputType->is<type::Array>() &&
outputType->get<type::Array>().itemType == type::Number
)
)
{
ctx.error("Type " + toString(*outputType) +
" is not interpolatable, and thus cannot be used as a " +
*interpName + " curve's output type.");
return ParseResult();
}
return outputType->match(
[&](const type::NumberType&) -> ParseResult {
return interpolator.match([&](const auto& interpolator_) {
return ParseResult(std::make_unique<Curve<double>>(
*outputType, interpolator_, std::move(*input), std::move(stops)
));
});
},
[&](const type::ColorType&) -> ParseResult {
return interpolator.match([&](const auto& interpolator_) {
return ParseResult(std::make_unique<Curve<mbgl::Color>>(
*outputType, interpolator_, std::move(*input), std::move(stops)
));
});
},
[&](const type::Array& arrayType) -> ParseResult {
return interpolator.match(
[&](const StepInterpolator& stepInterpolator) {
return ParseResult(std::make_unique<Curve<std::vector<Value>>>(
*outputType, stepInterpolator, std::move(*input), std::move(stops)
));
},
[&](const auto& continuousInterpolator) {
if (arrayType.itemType != type::Number || !arrayType.N) {
assert(false); // interpolability already checked above.
return ParseResult();
}
return ParseResult(std::make_unique<Curve<std::vector<Value>>>(
*outputType, continuousInterpolator, std::move(*input), std::move(stops)
));
}
);
},
[&](const auto&) {
// Null, Boolean, String, Object, Value output types only support step interpolation
return interpolator.match(
[&](const StepInterpolator& stepInterpolator) {
return ParseResult(std::make_unique<Curve<double>>(
*outputType, stepInterpolator, std::move(*input), std::move(stops)
));
},
[&](const auto&) {
assert(false); // interpolability already checked above.
return ParseResult();
}
);
}
);
}
};
} // namespace expression
} // namespace style
} // namespace mbgl
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