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Diffstat (limited to 'src/mbgl/style/expression/parsing_context.cpp')
| -rw-r--r-- | src/mbgl/style/expression/parsing_context.cpp | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/src/mbgl/style/expression/parsing_context.cpp b/src/mbgl/style/expression/parsing_context.cpp new file mode 100644 index 0000000000..501ba2749f --- /dev/null +++ b/src/mbgl/style/expression/parsing_context.cpp @@ -0,0 +1,208 @@ + +#include <mbgl/style/expression/parsing_context.hpp> +#include <mbgl/style/expression/check_subtype.hpp> +#include <mbgl/style/expression/is_constant.hpp> +#include <mbgl/style/expression/type.hpp> + +#include <mbgl/style/expression/expression.hpp> +#include <mbgl/style/expression/at.hpp> +#include <mbgl/style/expression/array_assertion.hpp> +#include <mbgl/style/expression/assertion.hpp> +#include <mbgl/style/expression/boolean_operator.hpp> +#include <mbgl/style/expression/case.hpp> +#include <mbgl/style/expression/coalesce.hpp> +#include <mbgl/style/expression/coercion.hpp> +#include <mbgl/style/expression/compound_expression.hpp> +#include <mbgl/style/expression/interpolate.hpp> +#include <mbgl/style/expression/let.hpp> +#include <mbgl/style/expression/literal.hpp> +#include <mbgl/style/expression/match.hpp> +#include <mbgl/style/expression/step.hpp> + +#include <mbgl/style/expression/find_zoom_curve.hpp> + +#include <mbgl/style/conversion/get_json_type.hpp> + +#include <mbgl/util/string.hpp> + +namespace mbgl { +namespace style { +namespace expression { + +bool isConstant(const Expression& expression) { + if (dynamic_cast<const Var*>(&expression)) { + return false; + } + + if (auto compound = dynamic_cast<const CompoundExpressionBase*>(&expression)) { + if (compound->getName() == "error") { + return false; + } + } + + bool literalArgs = true; + expression.eachChild([&](const Expression& child) { + if (!dynamic_cast<const Literal*>(&child)) { + literalArgs = false; + } + }); + if (!literalArgs) { + return false; + } + + return isFeatureConstant(expression) && + isGlobalPropertyConstant(expression, std::array<std::string, 2>{{"zoom", "heatmap-density"}}); +} + +using namespace mbgl::style::conversion; + +ParseResult ParsingContext::parse(const Convertible& value, std::size_t index_, optional<type::Type> expected_) { + ParsingContext child(key + "[" + util::toString(index_) + "]", + errors, + std::move(expected_), + scope); + return child.parse(value); +} + +ParseResult ParsingContext::parse(const Convertible& value, std::size_t index_, optional<type::Type> expected_, + const std::map<std::string, std::shared_ptr<Expression>>& bindings) { + ParsingContext child(key + "[" + util::toString(index_) + "]", + errors, + std::move(expected_), + std::make_shared<detail::Scope>(bindings, scope)); + return child.parse(value); +} + +const ExpressionRegistry& getExpressionRegistry() { + static ExpressionRegistry registry {{ + {"all", All::parse}, + {"any", Any::parse}, + {"array", ArrayAssertion::parse}, + {"at", At::parse}, + {"boolean", Assertion::parse}, + {"case", Case::parse}, + {"coalesce", Coalesce::parse}, + {"interpolate", parseInterpolate}, + {"let", Let::parse}, + {"literal", Literal::parse}, + {"match", parseMatch}, + {"number", Assertion::parse}, + {"object", Assertion::parse}, + {"step", Step::parse}, + {"string", Assertion::parse}, + {"to-color", Coercion::parse}, + {"to-number", Coercion::parse}, + {"var", Var::parse} + }}; + return registry; +} + +ParseResult ParsingContext::parse(const Convertible& value) +{ + ParseResult parsed; + + if (isArray(value)) { + const std::size_t length = arrayLength(value); + if (length == 0) { + error(R"(Expected an array with at least one element. If you wanted a literal array, use ["literal", []].)"); + return ParseResult(); + } + + const optional<std::string> op = toString(arrayMember(value, 0)); + if (!op) { + error( + "Expression name must be a string, but found " + getJSONType(arrayMember(value, 0)) + + R"( instead. If you wanted a literal array, use ["literal", [...]].)", + 0 + ); + return ParseResult(); + } + + const ExpressionRegistry& registry = getExpressionRegistry(); + auto parseFunction = registry.find(*op); + if (parseFunction != registry.end()) { + parsed = parseFunction->second(value, *this); + } else { + parsed = parseCompoundExpression(*op, value, *this); + } + } else { + parsed = Literal::parse(value, *this); + } + + if (!parsed) { + assert(errors->size() > 0); + } else if (expected) { + auto wrapForType = [&](const type::Type& target, std::unique_ptr<Expression> expression) -> std::unique_ptr<Expression> { + std::vector<std::unique_ptr<Expression>> args; + args.push_back(std::move(expression)); + if (target == type::Color) { + return std::make_unique<Coercion>(target, std::move(args)); + } else { + return std::make_unique<Assertion>(target, std::move(args)); + } + }; + + const type::Type actual = (*parsed)->getType(); + if (*expected == type::Color && (actual == type::String || actual == type::Value)) { + parsed = wrapForType(type::Color, std::move(*parsed)); + } else if ((*expected == type::String || *expected == type::Number || *expected == type::Boolean) && actual == type::Value) { + parsed = wrapForType(*expected, std::move(*parsed)); + } + + checkType((*parsed)->getType()); + if (errors->size() > 0) { + return ParseResult(); + } + } + + // If an expression's arguments are all literals, we can evaluate + // it immediately and replace it with a literal value in the + // parsed result. + if (parsed && !dynamic_cast<Literal *>(parsed->get()) && isConstant(**parsed)) { + EvaluationContext params(nullptr); + EvaluationResult evaluated((*parsed)->evaluate(params)); + if (!evaluated) { + error(evaluated.error().message); + return ParseResult(); + } + + const type::Type type = (*parsed)->getType(); + if (type.is<type::Array>()) { + // keep the original expression's array type, even if the evaluated + // type is more specific. + return ParseResult(std::make_unique<Literal>( + type.get<type::Array>(), + evaluated->get<std::vector<Value>>()) + ); + } else { + return ParseResult(std::make_unique<Literal>(*evaluated)); + } + } + + // if this is the root expression, enforce constraints on the use ["zoom"]. + if (key.size() == 0 && parsed && !isZoomConstant(**parsed)) { + optional<variant<const InterpolateBase*, const Step*, ParsingError>> zoomCurve = findZoomCurve(parsed->get()); + if (!zoomCurve) { + error(R"("zoom" expression may only be used as input to a top-level "step" or "interpolate" expression.)"); + return ParseResult(); + } else if (zoomCurve->is<ParsingError>()) { + error(zoomCurve->get<ParsingError>().message); + return ParseResult(); + } + } + + return parsed; +} + +optional<std::string> ParsingContext::checkType(const type::Type& t) { + assert(expected); + optional<std::string> err = type::checkSubtype(*expected, t); + if (err) { + error(*err); + } + return err; +} + +} // namespace expression +} // namespace style +} // namespace mbgl |