bkietz commented on a change in pull request #8894: URL: https://github.com/apache/arrow/pull/8894#discussion_r552038470
########## File path: cpp/src/arrow/dataset/expression.cc ########## @@ -0,0 +1,1177 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +#include "arrow/dataset/expression.h" + +#include <unordered_map> +#include <unordered_set> + +#include "arrow/chunked_array.h" +#include "arrow/compute/exec_internal.h" +#include "arrow/dataset/expression_internal.h" +#include "arrow/io/memory.h" +#include "arrow/ipc/reader.h" +#include "arrow/ipc/writer.h" +#include "arrow/util/key_value_metadata.h" +#include "arrow/util/logging.h" +#include "arrow/util/optional.h" +#include "arrow/util/string.h" +#include "arrow/util/value_parsing.h" + +namespace arrow { + +using internal::checked_cast; +using internal::checked_pointer_cast; + +namespace dataset { + +Expression::Expression(Call call) : impl_(std::make_shared<Impl>(std::move(call))) {} + +Expression::Expression(Datum literal) + : impl_(std::make_shared<Impl>(std::move(literal))) {} + +Expression::Expression(Parameter parameter) + : impl_(std::make_shared<Impl>(std::move(parameter))) {} + +Expression literal(Datum lit) { return Expression(std::move(lit)); } + +Expression field_ref(FieldRef ref) { + return Expression(Expression::Parameter{std::move(ref), {}}); +} + +Expression call(std::string function, std::vector<Expression> arguments, + std::shared_ptr<compute::FunctionOptions> options) { + Expression::Call call; + call.function_name = std::move(function); + call.arguments = std::move(arguments); + call.options = std::move(options); + return Expression(std::move(call)); +} + +const Datum* Expression::literal() const { return util::get_if<Datum>(impl_.get()); } + +const FieldRef* Expression::field_ref() const { + if (auto parameter = util::get_if<Parameter>(impl_.get())) { + return ¶meter->ref; + } + return nullptr; +} + +const Expression::Call* Expression::call() const { + return util::get_if<Call>(impl_.get()); +} + +ValueDescr Expression::descr() const { + if (impl_ == nullptr) return {}; + + if (auto lit = literal()) { + return lit->descr(); + } + + if (auto parameter = util::get_if<Parameter>(impl_.get())) { + return parameter->descr; + } + + return CallNotNull(*this)->descr; +} + +std::string Expression::ToString() const { + if (auto lit = literal()) { + if (lit->is_scalar()) { + switch (lit->type()->id()) { + case Type::STRING: + case Type::LARGE_STRING: + return '"' + + Escape(util::string_view(*lit->scalar_as<BaseBinaryScalar>().value)) + + '"'; + + case Type::BINARY: + case Type::FIXED_SIZE_BINARY: + case Type::LARGE_BINARY: + return '"' + lit->scalar_as<BaseBinaryScalar>().value->ToHexString() + '"'; + + default: + break; + } + return lit->scalar()->ToString(); + } + return lit->ToString(); + } + + if (auto ref = field_ref()) { + if (auto name = ref->name()) { + return *name; + } + if (auto path = ref->field_path()) { + return path->ToString(); + } + return ref->ToString(); + } + + auto call = CallNotNull(*this); + auto binary = [&](std::string op) { + return "(" + call->arguments[0].ToString() + " " + op + " " + + call->arguments[1].ToString() + ")"; + }; + + if (auto cmp = Comparison::Get(call->function_name)) { + return binary(Comparison::GetOp(*cmp)); + } + + constexpr util::string_view kleene = "_kleene"; + if (util::string_view{call->function_name}.ends_with(kleene)) { + auto op = call->function_name.substr(0, call->function_name.size() - kleene.size()); + return binary(std::move(op)); + } + + if (auto options = GetStructOptions(*call)) { + std::string out = "{"; + auto argument = call->arguments.begin(); + for (const auto& field_name : options->field_names) { + out += field_name + "=" + argument++->ToString() + ", "; + } + out.resize(out.size() - 1); + out.back() = '}'; + return out; + } + + std::string out = call->function_name + "("; + for (const auto& arg : call->arguments) { + out += arg.ToString() + ", "; + } + + if (call->options == nullptr) { + out.resize(out.size() - 1); + out.back() = ')'; + return out; + } + + if (auto options = GetSetLookupOptions(*call)) { + DCHECK_EQ(options->value_set.kind(), Datum::ARRAY); + out += "value_set=" + options->value_set.make_array()->ToString(); + if (options->skip_nulls) { + out += ", skip_nulls"; + } + return out + ")"; + } + + if (auto options = GetCastOptions(*call)) { + if (options->to_type == nullptr) { + return out + "to_type=<INVALID NOT PROVIDED>)"; + } + out += "to_type=" + options->to_type->ToString(); + if (options->allow_int_overflow) out += ", allow_int_overflow"; + if (options->allow_time_truncate) out += ", allow_time_truncate"; + if (options->allow_time_overflow) out += ", allow_time_overflow"; + if (options->allow_decimal_truncate) out += ", allow_decimal_truncate"; + if (options->allow_float_truncate) out += ", allow_float_truncate"; + if (options->allow_invalid_utf8) out += ", allow_invalid_utf8"; + return out + ")"; + } + + if (auto options = GetStrptimeOptions(*call)) { + return out + "format=" + options->format + + ", unit=" + internal::ToString(options->unit) + ")"; + } + + return out + "{NON-REPRESENTABLE OPTIONS})"; +} + +void PrintTo(const Expression& expr, std::ostream* os) { + *os << expr.ToString(); + if (expr.IsBound()) { + *os << "[bound]"; + } +} + +bool Expression::Equals(const Expression& other) const { + if (Identical(*this, other)) return true; + + if (impl_->index() != other.impl_->index()) { + return false; + } + + if (auto lit = literal()) { + return lit->Equals(*other.literal()); + } + + if (auto ref = field_ref()) { + return ref->Equals(*other.field_ref()); + } + + auto call = CallNotNull(*this); + auto other_call = CallNotNull(other); + + if (call->function_name != other_call->function_name || + call->kernel != other_call->kernel) { + return false; + } + + for (size_t i = 0; i < call->arguments.size(); ++i) { + if (!call->arguments[i].Equals(other_call->arguments[i])) { + return false; + } + } + + if (call->options == other_call->options) return true; + + if (auto options = GetSetLookupOptions(*call)) { + auto other_options = GetSetLookupOptions(*other_call); + return options->value_set == other_options->value_set && + options->skip_nulls == other_options->skip_nulls; + } + + if (auto options = GetCastOptions(*call)) { + auto other_options = GetCastOptions(*other_call); + for (auto safety_opt : { + &compute::CastOptions::allow_int_overflow, + &compute::CastOptions::allow_time_truncate, + &compute::CastOptions::allow_time_overflow, + &compute::CastOptions::allow_decimal_truncate, + &compute::CastOptions::allow_float_truncate, + &compute::CastOptions::allow_invalid_utf8, + }) { + if (options->*safety_opt != other_options->*safety_opt) return false; + } + return options->to_type->Equals(other_options->to_type); + } + + if (auto options = GetStructOptions(*call)) { + auto other_options = GetStructOptions(*other_call); + return options->field_names == other_options->field_names; + } + + if (auto options = GetStrptimeOptions(*call)) { + auto other_options = GetStrptimeOptions(*other_call); + return options->format == other_options->format && + options->unit == other_options->unit; + } + + ARROW_LOG(WARNING) << "comparing unknown FunctionOptions for function " + << call->function_name; + return false; +} + +size_t Expression::hash() const { + if (auto lit = literal()) { + if (lit->is_scalar()) { + return Scalar::Hash::hash(*lit->scalar()); + } + return 0; + } + + if (auto ref = field_ref()) { + return ref->hash(); + } + + auto call = CallNotNull(*this); + + size_t out = std::hash<std::string>{}(call->function_name); + for (const auto& arg : call->arguments) { + out ^= arg.hash(); + } + return out; +} + +bool Expression::IsBound() const { + if (descr().type == nullptr) return false; + + if (auto lit = literal()) return true; + + if (auto ref = field_ref()) return true; + + auto call = CallNotNull(*this); + + for (const Expression& arg : call->arguments) { + if (!arg.IsBound()) return false; + } + + return call->kernel != nullptr; +} + +bool Expression::IsScalarExpression() const { + if (auto lit = literal()) { + return lit->is_scalar(); + } + + // FIXME handle case where a list's item field is referenced + if (auto ref = field_ref()) return true; + + auto call = CallNotNull(*this); + + for (const Expression& arg : call->arguments) { + if (!arg.IsScalarExpression()) return false; + } + + if (call->function) { + return call->function->kind() == compute::Function::SCALAR; + } + + // this expression is not bound; make a best guess based on + // the default function registry + if (auto function = compute::GetFunctionRegistry() + ->GetFunction(call->function_name) + .ValueOr(nullptr)) { + return function->kind() == compute::Function::SCALAR; + } + + // unknown function or other error; conservatively return false + return false; +} + +bool Expression::IsNullLiteral() const { + if (auto lit = literal()) { + if (lit->null_count() == lit->length()) { + return true; + } + } + + return false; +} + +bool Expression::IsSatisfiable() const { + if (descr().type && descr().type->id() == Type::NA) { + return false; + } + + if (auto lit = literal()) { + if (lit->null_count() == lit->length()) { + return false; + } + + if (lit->is_scalar() && lit->type()->id() == Type::BOOL) { + return lit->scalar_as<BooleanScalar>().value; + } + } + + if (auto ref = field_ref()) { + return true; + } + + return true; +} + +inline bool KernelStateIsImmutable(const std::string& function) { + // XXX maybe just add Kernel::state_is_immutable or so? + + // known functions with non-null but nevertheless immutable KernelState + static std::unordered_set<std::string> names = { + "is_in", "index_in", "cast", "struct", "strptime", + }; + + return names.find(function) != names.end(); +} + +Result<std::unique_ptr<compute::KernelState>> InitKernelState( + const Expression::Call& call, compute::ExecContext* exec_context) { + if (!call.kernel->init) return nullptr; + + compute::KernelContext kernel_context(exec_context); + auto kernel_state = call.kernel->init( + &kernel_context, {call.kernel, GetDescriptors(call.arguments), call.options.get()}); + + RETURN_NOT_OK(kernel_context.status()); + return std::move(kernel_state); +} + +Status MaybeInsertCast(std::shared_ptr<DataType> to_type, Expression* expr) { + if (expr->descr().type->Equals(to_type)) { + return Status::OK(); + } + + if (auto lit = expr->literal()) { + ARROW_ASSIGN_OR_RAISE(Datum new_lit, compute::Cast(*lit, to_type)); + *expr = literal(std::move(new_lit)); + return Status::OK(); + } + + // FIXME the resulting cast Call must be bound but this is a hack + auto with_cast = call("cast", {literal(MakeNullScalar(expr->descr().type))}, + compute::CastOptions::Safe(to_type)); + + static ValueDescr ignored_descr; + ARROW_ASSIGN_OR_RAISE(with_cast, with_cast.Bind(ignored_descr)); + + auto call_with_cast = *CallNotNull(with_cast); + call_with_cast.arguments[0] = std::move(*expr); + call_with_cast.descr = ValueDescr{std::move(to_type), expr->descr().shape}; + + *expr = Expression(std::move(call_with_cast)); + return Status::OK(); +} + +Status InsertImplicitCasts(Expression::Call* call) { + DCHECK(std::all_of(call->arguments.begin(), call->arguments.end(), + [](const Expression& argument) { return argument.IsBound(); })); + + if (IsSameTypesBinary(call->function_name)) { + for (auto&& argument : call->arguments) { + if (auto value_type = GetDictionaryValueType(argument.descr().type)) { + RETURN_NOT_OK(MaybeInsertCast(std::move(value_type), &argument)); + } + } + + if (call->arguments[0].descr().shape == ValueDescr::SCALAR) { + // argument 0 is scalar so casting is cheap + return MaybeInsertCast(call->arguments[1].descr().type, &call->arguments[0]); + } + + // cast argument 1 unconditionally + return MaybeInsertCast(call->arguments[0].descr().type, &call->arguments[1]); + } + + if (auto options = GetSetLookupOptions(*call)) { + if (auto value_type = GetDictionaryValueType(call->arguments[0].descr().type)) { + // DICTIONARY input is not supported; decode it. + RETURN_NOT_OK(MaybeInsertCast(std::move(value_type), &call->arguments[0])); + } + + if (options->value_set.type()->id() == Type::DICTIONARY) { + // DICTIONARY value_set is not supported; decode it. + auto new_options = std::make_shared<compute::SetLookupOptions>(*options); + RETURN_NOT_OK(EnsureNotDictionary(&new_options->value_set)); + options = new_options.get(); + call->options = std::move(new_options); + } + + if (!options->value_set.type()->Equals(call->arguments[0].descr().type)) { + // The value_set is assumed smaller than inputs, casting it should be cheaper. + auto new_options = std::make_shared<compute::SetLookupOptions>(*options); + ARROW_ASSIGN_OR_RAISE(new_options->value_set, + compute::Cast(std::move(new_options->value_set), + call->arguments[0].descr().type)); + options = new_options.get(); + call->options = std::move(new_options); + } + + return Status::OK(); + } + + return Status::OK(); +} + +Result<Expression> Expression::Bind(ValueDescr in, + compute::ExecContext* exec_context) const { + if (exec_context == nullptr) { + compute::ExecContext exec_context; + return Bind(std::move(in), &exec_context); + } + + if (literal()) return *this; + + if (auto ref = field_ref()) { + ARROW_ASSIGN_OR_RAISE(auto field, ref->GetOneOrNone(*in.type)); + auto descr = field ? ValueDescr{field->type(), in.shape} : ValueDescr::Scalar(null()); + return Expression{Parameter{*ref, std::move(descr)}}; + } + + auto bound_call = *CallNotNull(*this); + + ARROW_ASSIGN_OR_RAISE(bound_call.function, GetFunction(bound_call, exec_context)); + + for (auto&& argument : bound_call.arguments) { + ARROW_ASSIGN_OR_RAISE(argument, argument.Bind(in, exec_context)); + } + RETURN_NOT_OK(InsertImplicitCasts(&bound_call)); + + auto descrs = GetDescriptors(bound_call.arguments); + ARROW_ASSIGN_OR_RAISE(bound_call.kernel, bound_call.function->DispatchExact(descrs)); + + compute::KernelContext kernel_context(exec_context); + ARROW_ASSIGN_OR_RAISE(bound_call.kernel_state, + InitKernelState(bound_call, exec_context)); + kernel_context.SetState(bound_call.kernel_state.get()); + + ARROW_ASSIGN_OR_RAISE( + bound_call.descr, + bound_call.kernel->signature->out_type().Resolve(&kernel_context, descrs)); + + return Expression(std::move(bound_call)); +} + +Result<Expression> Expression::Bind(const Schema& in_schema, + compute::ExecContext* exec_context) const { + return Bind(ValueDescr::Array(struct_(in_schema.fields())), exec_context); +} + +Result<Datum> ExecuteScalarExpression(const Expression& expr, const Datum& input, + compute::ExecContext* exec_context) { + if (exec_context == nullptr) { + compute::ExecContext exec_context; + return ExecuteScalarExpression(expr, input, &exec_context); + } + + if (!expr.IsBound()) { + return Status::Invalid("Cannot Execute unbound expression."); + } + + if (!expr.IsScalarExpression()) { + return Status::Invalid( + "ExecuteScalarExpression cannot Execute non-scalar expression ", expr.ToString()); + } + + if (auto lit = expr.literal()) return *lit; + + if (auto ref = expr.field_ref()) { + ARROW_ASSIGN_OR_RAISE(Datum field, GetDatumField(*ref, input)); + + if (field.descr() != expr.descr()) { + // Refernced field was present but didn't have the expected type. + // Should we just error here? For now, pay dispatch cost and just cast. + ARROW_ASSIGN_OR_RAISE( + field, compute::Cast(field, expr.descr().type, compute::CastOptions::Safe(), + exec_context)); + } + + return field; + } + + auto call = CallNotNull(expr); + + std::vector<Datum> arguments(call->arguments.size()); + for (size_t i = 0; i < arguments.size(); ++i) { + ARROW_ASSIGN_OR_RAISE( + arguments[i], ExecuteScalarExpression(call->arguments[i], input, exec_context)); + } + + auto executor = compute::detail::KernelExecutor::MakeScalar(); + + compute::KernelContext kernel_context(exec_context); + kernel_context.SetState(call->kernel_state.get()); + + auto kernel = call->kernel; + auto descrs = GetDescriptors(arguments); + auto options = call->options.get(); + RETURN_NOT_OK(executor->Init(&kernel_context, {kernel, descrs, options})); + + auto listener = std::make_shared<compute::detail::DatumAccumulator>(); + RETURN_NOT_OK(executor->Execute(arguments, listener.get())); + return executor->WrapResults(arguments, listener->values()); +} + +std::array<std::pair<const Expression&, const Expression&>, 2> +ArgumentsAndFlippedArguments(const Expression::Call& call) { + DCHECK_EQ(call.arguments.size(), 2); + return {std::pair<const Expression&, const Expression&>{call.arguments[0], + call.arguments[1]}, + std::pair<const Expression&, const Expression&>{call.arguments[1], + call.arguments[0]}}; +} + +template <typename BinOp, typename It, + typename Out = typename std::iterator_traits<It>::value_type> +util::optional<Out> FoldLeft(It begin, It end, const BinOp& bin_op) { + if (begin == end) return util::nullopt; + + Out folded = std::move(*begin++); + while (begin != end) { + folded = bin_op(std::move(folded), std::move(*begin++)); + } + return folded; +} + +util::optional<compute::NullHandling::type> GetNullHandling( + const Expression::Call& call) { + if (call.function && call.function->kind() == compute::Function::SCALAR) { + return static_cast<const compute::ScalarKernel*>(call.kernel)->null_handling; + } + return util::nullopt; +} + +bool DefinitelyNotNull(const Expression& expr) { + DCHECK(expr.IsBound()); + + if (expr.literal()) { + return !expr.IsNullLiteral(); + } + + if (expr.field_ref()) return false; + + auto call = CallNotNull(expr); + if (auto null_handling = GetNullHandling(*call)) { + if (null_handling == compute::NullHandling::OUTPUT_NOT_NULL) { + return true; + } + if (null_handling == compute::NullHandling::INTERSECTION) { + return std::all_of(call->arguments.begin(), call->arguments.end(), + DefinitelyNotNull); + } + } + + return false; +} + +std::vector<FieldRef> FieldsInExpression(const Expression& expr) { + if (auto lit = expr.literal()) return {}; + + if (auto ref = expr.field_ref()) { + return {*ref}; + } + + std::vector<FieldRef> fields; + for (const Expression& arg : CallNotNull(expr)->arguments) { + auto argument_fields = FieldsInExpression(arg); + std::move(argument_fields.begin(), argument_fields.end(), std::back_inserter(fields)); + } + return fields; +} + +Result<Expression> FoldConstants(Expression expr) { + return Modify( + std::move(expr), [](Expression expr) { return expr; }, + [](Expression expr, ...) -> Result<Expression> { + auto call = CallNotNull(expr); + if (std::all_of(call->arguments.begin(), call->arguments.end(), + [](const Expression& argument) { return argument.literal(); })) { + // all arguments are literal; we can evaluate this subexpression *now* + static const Datum ignored_input; + ARROW_ASSIGN_OR_RAISE(Datum constant, + ExecuteScalarExpression(expr, ignored_input)); + + return literal(std::move(constant)); + } + + // XXX the following should probably be in a registry of passes instead + // of inline + + if (GetNullHandling(*call) == compute::NullHandling::INTERSECTION) { + // kernels which always produce intersected validity can be resolved + // to null *now* if any of their inputs is a null literal + for (const auto& argument : call->arguments) { + if (argument.IsNullLiteral()) { + return argument; + } + } + } + + if (call->function_name == "and_kleene") { + for (auto args : ArgumentsAndFlippedArguments(*call)) { + // true and x == x + if (args.first == literal(true)) return args.second; + + // false and x == false + if (args.first == literal(false)) return args.first; + + // x and x == x + if (args.first == args.second) return args.first; + } + return expr; + } + + if (call->function_name == "or_kleene") { + for (auto args : ArgumentsAndFlippedArguments(*call)) { + // false or x == x + if (args.first == literal(false)) return args.second; + + // true or x == true + if (args.first == literal(true)) return args.first; + + // x or x == x + if (args.first == args.second) return args.first; + } + return expr; + } + + return expr; + }); +} + +inline std::vector<Expression> GuaranteeConjunctionMembers( + const Expression& guaranteed_true_predicate) { + auto guarantee = guaranteed_true_predicate.call(); + if (!guarantee || guarantee->function_name != "and_kleene") { + return {guaranteed_true_predicate}; + } + return FlattenedAssociativeChain(guaranteed_true_predicate).fringe; +} + +// Conjunction members which are represented in known_values are erased from +// conjunction_members +Status ExtractKnownFieldValuesImpl( + std::vector<Expression>* conjunction_members, + std::unordered_map<FieldRef, Datum, FieldRef::Hash>* known_values) { + auto unconsumed_end = + std::partition(conjunction_members->begin(), conjunction_members->end(), + [](const Expression& expr) { + // search for an equality conditions between a field and a literal + auto call = expr.call(); + if (!call) return true; + + if (call->function_name == "equal") { + auto ref = call->arguments[0].field_ref(); + auto lit = call->arguments[1].literal(); + return !(ref && lit); + } + + return true; + }); + + for (auto it = unconsumed_end; it != conjunction_members->end(); ++it) { + auto call = CallNotNull(*it); + + auto ref = call->arguments[0].field_ref(); + auto lit = call->arguments[1].literal(); + + auto it_success = known_values->emplace(*ref, *lit); + if (it_success.second) continue; + + // A value was already known for ref; check it + auto ref_lit = it_success.first; + if (*lit != ref_lit->second) { + return Status::Invalid("Conflicting guarantees: (", ref->ToString(), + " == ", lit->ToString(), ") vs (", ref->ToString(), + " == ", ref_lit->second.ToString()); + } + } + + conjunction_members->erase(unconsumed_end, conjunction_members->end()); + + return Status::OK(); +} + +Result<std::unordered_map<FieldRef, Datum, FieldRef::Hash>> ExtractKnownFieldValues( + const Expression& guaranteed_true_predicate) { + auto conjunction_members = GuaranteeConjunctionMembers(guaranteed_true_predicate); + std::unordered_map<FieldRef, Datum, FieldRef::Hash> known_values; + RETURN_NOT_OK(ExtractKnownFieldValuesImpl(&conjunction_members, &known_values)); + return known_values; +} + +Result<Expression> ReplaceFieldsWithKnownValues( + const std::unordered_map<FieldRef, Datum, FieldRef::Hash>& known_values, + Expression expr) { + if (!expr.IsBound()) { + return Status::Invalid( + "ReplaceFieldsWithKnownValues called on an unbound Expression"); + } + + return Modify( + std::move(expr), + [&known_values](Expression expr) -> Result<Expression> { + if (auto ref = expr.field_ref()) { + auto it = known_values.find(*ref); + if (it != known_values.end()) { + ARROW_ASSIGN_OR_RAISE(Datum lit, + compute::Cast(it->second, expr.descr().type)); + return literal(std::move(lit)); + } + } + return expr; + }, + [](Expression expr, ...) { return expr; }); +} + +inline bool IsBinaryAssociativeCommutative(const Expression::Call& call) { + static std::unordered_set<std::string> binary_associative_commutative{ + "and", "or", "and_kleene", "or_kleene", "xor", + "multiply", "add", "multiply_checked", "add_checked"}; + + auto it = binary_associative_commutative.find(call.function_name); + return it != binary_associative_commutative.end(); +} + +Result<Expression> Canonicalize(Expression expr, compute::ExecContext* exec_context) { + if (exec_context == nullptr) { + compute::ExecContext exec_context; + return Canonicalize(std::move(expr), &exec_context); + } + + // If potentially reconstructing more deeply than a call's immediate arguments + // (for example, when reorganizing an associative chain), add expressions to this set to + // avoid unnecessary work + struct { + std::unordered_set<Expression, Expression::Hash> set_; + + bool operator()(const Expression& expr) const { + return set_.find(expr) != set_.end(); + } + + void Add(std::vector<Expression> exprs) { + std::move(exprs.begin(), exprs.end(), std::inserter(set_, set_.end())); + } + } AlreadyCanonicalized; + + return Modify( + std::move(expr), + [&AlreadyCanonicalized, exec_context](Expression expr) -> Result<Expression> { + auto call = expr.call(); + if (!call) return expr; + + if (AlreadyCanonicalized(expr)) return expr; + + if (IsBinaryAssociativeCommutative(*call)) { + struct { + int Priority(const Expression& operand) const { + // order literals first, starting with nulls + if (operand.IsNullLiteral()) return 0; + if (operand.literal()) return 1; + return 2; + } + bool operator()(const Expression& l, const Expression& r) const { + return Priority(l) < Priority(r); + } + } CanonicalOrdering; + + FlattenedAssociativeChain chain(expr); + if (chain.was_left_folded && + std::is_sorted(chain.fringe.begin(), chain.fringe.end(), + CanonicalOrdering)) { + AlreadyCanonicalized.Add(std::move(chain.exprs)); + return expr; + } + + std::stable_sort(chain.fringe.begin(), chain.fringe.end(), CanonicalOrdering); + + // fold the chain back up + auto folded = + FoldLeft(chain.fringe.begin(), chain.fringe.end(), + [call, &AlreadyCanonicalized](Expression l, Expression r) { + auto canonicalized_call = *call; + canonicalized_call.arguments = {std::move(l), std::move(r)}; + Expression expr(std::move(canonicalized_call)); + AlreadyCanonicalized.Add({expr}); + return expr; + }); + return std::move(*folded); + } + + if (auto cmp = Comparison::Get(call->function_name)) { + if (call->arguments[0].literal() && !call->arguments[1].literal()) { + // ensure that literals are on comparisons' RHS + auto flipped_call = *call; + flipped_call.function_name = + Comparison::GetName(Comparison::GetFlipped(*cmp)); + // look up the flipped kernel + // TODO extract a helper for use here and in Bind + ARROW_ASSIGN_OR_RAISE( + auto function, + exec_context->func_registry()->GetFunction(flipped_call.function_name)); + + auto descrs = GetDescriptors(flipped_call.arguments); + ARROW_ASSIGN_OR_RAISE(flipped_call.kernel, function->DispatchExact(descrs)); + + std::swap(flipped_call.arguments[0], flipped_call.arguments[1]); + return Expression(std::move(flipped_call)); + } + } + + return expr; + }, + [](Expression expr, ...) { return expr; }); +} + +Result<Expression> DirectComparisonSimplification(Expression expr, + const Expression::Call& guarantee) { + return Modify( + std::move(expr), [](Expression expr) { return expr; }, + [&guarantee](Expression expr, ...) -> Result<Expression> { + auto call = expr.call(); + if (!call) return expr; + + // Ensure both calls are comparisons with equal LHS and scalar RHS + auto cmp = Comparison::Get(expr); + auto cmp_guarantee = Comparison::Get(guarantee.function_name); + if (!cmp || !cmp_guarantee) return expr; + + if (call->arguments[0] != guarantee.arguments[0]) return expr; + + auto rhs = call->arguments[1].literal(); + auto guarantee_rhs = guarantee.arguments[1].literal(); + if (!rhs || !guarantee_rhs) return expr; + + if (!rhs->is_scalar() || !guarantee_rhs->is_scalar()) { + return expr; + } + + ARROW_ASSIGN_OR_RAISE(auto cmp_rhs_guarantee_rhs, + Comparison::Execute(*rhs, *guarantee_rhs)); + DCHECK_NE(cmp_rhs_guarantee_rhs, Comparison::NA); + + if (cmp_rhs_guarantee_rhs == Comparison::EQUAL) { + // RHS of filter is equal to RHS of guarantee + + if ((*cmp_guarantee & *cmp) == *cmp_guarantee) { + // guarantee is a subset of filter, so all data will be included + return literal(true); + } + + if ((*cmp_guarantee & *cmp) == 0) { + // guarantee disjoint with filter, so all data will be excluded + return literal(false); + } + + return expr; + } + + if (*cmp_guarantee & cmp_rhs_guarantee_rhs) { + // unusable guarantee + return expr; + } + + if (*cmp & Comparison::GetFlipped(cmp_rhs_guarantee_rhs)) { + // x > 1, x >= 1, x != 1 guaranteed by x >= 3 + return literal(true); + } else { + // x < 1, x <= 1, x == 1 unsatisfiable if x >= 3 + return literal(false); + } + }); +} + +Result<Expression> SimplifyWithGuarantee(Expression expr, + const Expression& guaranteed_true_predicate) { + auto conjunction_members = GuaranteeConjunctionMembers(guaranteed_true_predicate); + + std::unordered_map<FieldRef, Datum, FieldRef::Hash> known_values; + RETURN_NOT_OK(ExtractKnownFieldValuesImpl(&conjunction_members, &known_values)); + + ARROW_ASSIGN_OR_RAISE(expr, + ReplaceFieldsWithKnownValues(known_values, std::move(expr))); Review comment: Another reason for the separation is DirectComparisonSimplification requires that the simplified expression is also a comparison. This will not catch cases such as `is_in(a, [1,2,3])` where `a == 4` so we wouldn't be able to skip that partition ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
