mirror of
https://github.com/carbon-language/carbon-lang.git
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221 lines
8.7 KiB
C++
221 lines
8.7 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "explorer/interpreter/pattern_match.h"
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#include "explorer/ast/value.h"
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#include "explorer/common/arena.h"
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#include "explorer/common/trace_stream.h"
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#include "explorer/interpreter/action.h"
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#include "llvm/Support/Casting.h"
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using llvm::cast;
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using llvm::dyn_cast;
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namespace Carbon {
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static auto InitializePlaceholderValue(const ValueNodeView& value_node,
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ExpressionResult v,
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Nonnull<RuntimeScope*> bindings) {
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switch (value_node.expression_category()) {
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case ExpressionCategory::Reference:
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if (v.expression_category() == ExpressionCategory::Value ||
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v.expression_category() == ExpressionCategory::Reference) {
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// Build by copying from value or reference expression.
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bindings->Initialize(value_node, v.value());
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} else {
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// Location initialized by initializing expression, bind node to
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// address.
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CARBON_CHECK(v.address())
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<< "Missing location from initializing expression";
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bindings->Bind(value_node, *v.address());
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}
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break;
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case ExpressionCategory::Value:
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if (v.expression_category() == ExpressionCategory::Value) {
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// We assume values are strictly nested for now.
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bindings->BindValue(value_node, v.value());
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} else if (v.expression_category() == ExpressionCategory::Reference) {
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// Bind the reference expression value directly.
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CARBON_CHECK(v.address())
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<< "Missing location from reference expression";
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bindings->BindAndPin(value_node, *v.address());
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} else {
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// Location initialized by initializing expression, bind node to
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// address.
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CARBON_CHECK(v.address())
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<< "Missing location from initializing expression";
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bindings->Bind(value_node, *v.address());
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}
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break;
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case ExpressionCategory::Initializing:
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CARBON_FATAL() << "Cannot pattern match an initializing expression";
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break;
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}
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}
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auto PatternMatch(Nonnull<const Value*> p, ExpressionResult v,
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SourceLocation source_loc,
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std::optional<Nonnull<RuntimeScope*>> bindings,
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BindingMap& generic_args, Nonnull<TraceStream*> trace_stream,
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Nonnull<Arena*> arena) -> bool {
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if (trace_stream->is_enabled()) {
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*trace_stream << "match pattern " << *p << "\nfrom "
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<< ExpressionCategoryToString(v.expression_category())
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<< " expression with value " << *v.value() << "\n";
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}
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const auto make_expr_result =
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[](Nonnull<const Value*> v) -> ExpressionResult {
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if (const auto* expr_v = dyn_cast<ReferenceExpressionValue>(v)) {
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return ExpressionResult::Reference(expr_v->value(), expr_v->address());
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}
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return ExpressionResult::Value(v);
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};
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if (v.value()->kind() == Value::Kind::ReferenceExpressionValue) {
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return PatternMatch(p, make_expr_result(v.value()), source_loc, bindings,
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generic_args, trace_stream, arena);
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}
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switch (p->kind()) {
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case Value::Kind::BindingPlaceholderValue: {
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CARBON_CHECK(bindings.has_value());
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const auto& placeholder = cast<BindingPlaceholderValue>(*p);
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if (placeholder.value_node().has_value()) {
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InitializePlaceholderValue(*placeholder.value_node(), v, *bindings);
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}
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return true;
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}
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case Value::Kind::AddrValue: {
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const auto& addr = cast<AddrValue>(*p);
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CARBON_CHECK(v.value()->kind() == Value::Kind::LocationValue);
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const auto& location = cast<LocationValue>(*v.value());
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return PatternMatch(
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&addr.pattern(),
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ExpressionResult::Value(arena->New<PointerValue>(location.address())),
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source_loc, bindings, generic_args, trace_stream, arena);
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}
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case Value::Kind::VariableType: {
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const auto& var_type = cast<VariableType>(*p);
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generic_args[&var_type.binding()] = v.value();
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return true;
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}
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case Value::Kind::TupleType:
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case Value::Kind::TupleValue:
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switch (v.value()->kind()) {
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case Value::Kind::TupleType:
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case Value::Kind::TupleValue: {
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const auto& p_tup = cast<TupleValueBase>(*p);
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const auto& v_tup = cast<TupleValueBase>(*v.value());
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CARBON_CHECK(p_tup.elements().size() == v_tup.elements().size());
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for (size_t i = 0; i < p_tup.elements().size(); ++i) {
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if (!PatternMatch(p_tup.elements()[i],
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make_expr_result(v_tup.elements()[i]), source_loc,
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bindings, generic_args, trace_stream, arena)) {
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return false;
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}
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} // for
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return true;
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}
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case Value::Kind::UninitializedValue: {
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const auto& p_tup = cast<TupleValueBase>(*p);
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for (const auto& ele : p_tup.elements()) {
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if (!PatternMatch(ele,
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ExpressionResult::Value(
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arena->New<UninitializedValue>(ele)),
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source_loc, bindings, generic_args, trace_stream,
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arena)) {
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return false;
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}
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}
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return true;
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}
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default:
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CARBON_FATAL() << "expected a tuple value in pattern, not "
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<< *v.value();
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}
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case Value::Kind::StructValue: {
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const auto& p_struct = cast<StructValue>(*p);
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const auto& v_struct = cast<StructValue>(*v.value());
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CARBON_CHECK(p_struct.elements().size() == v_struct.elements().size());
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for (size_t i = 0; i < p_struct.elements().size(); ++i) {
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CARBON_CHECK(p_struct.elements()[i].name ==
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v_struct.elements()[i].name);
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if (!PatternMatch(p_struct.elements()[i].value,
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ExpressionResult::Value(v_struct.elements()[i].value),
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source_loc, bindings, generic_args, trace_stream,
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arena)) {
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return false;
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}
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}
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return true;
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}
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case Value::Kind::AlternativeValue:
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switch (v.value()->kind()) {
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case Value::Kind::AlternativeValue: {
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const auto& p_alt = cast<AlternativeValue>(*p);
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const auto& v_alt = cast<AlternativeValue>(*v.value());
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if (&p_alt.alternative() != &v_alt.alternative()) {
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return false;
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}
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CARBON_CHECK(p_alt.argument().has_value() ==
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v_alt.argument().has_value());
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if (!p_alt.argument().has_value()) {
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return true;
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}
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return PatternMatch(
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*p_alt.argument(), ExpressionResult::Value(*v_alt.argument()),
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source_loc, bindings, generic_args, trace_stream, arena);
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}
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default:
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CARBON_FATAL() << "expected a choice alternative in pattern, not "
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<< *v.value();
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}
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case Value::Kind::UninitializedValue:
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CARBON_FATAL() << "uninitialized value is not allowed in pattern "
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<< *v.value();
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case Value::Kind::FunctionType:
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switch (v.value()->kind()) {
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case Value::Kind::FunctionType: {
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const auto& p_fn = cast<FunctionType>(*p);
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const auto& v_fn = cast<FunctionType>(*v.value());
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if (!PatternMatch(&p_fn.parameters(),
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ExpressionResult::Value(&v_fn.parameters()),
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source_loc, bindings, generic_args, trace_stream,
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arena)) {
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return false;
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}
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if (!PatternMatch(&p_fn.return_type(),
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ExpressionResult::Value(&v_fn.return_type()),
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source_loc, bindings, generic_args, trace_stream,
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arena)) {
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return false;
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}
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return true;
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}
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default:
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return false;
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}
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case Value::Kind::AutoType:
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// `auto` matches any type, without binding any new names. We rely
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// on the typechecker to ensure that `v.value()` is a type.
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return true;
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case Value::Kind::StaticArrayType: {
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switch (v.value()->kind()) {
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case Value::Kind::TupleType:
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case Value::Kind::TupleValue: {
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return true;
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}
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case Value::Kind::StaticArrayType: {
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const auto& v_arr = cast<StaticArrayType>(*v.value());
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return v_arr.has_size();
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}
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default:
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return false;
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}
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}
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default:
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return ValueEqual(p, v.value(), std::nullopt);
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}
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}
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} // namespace Carbon
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