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https://github.com/carbon-language/carbon-lang.git
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Geoff RomerandJon Meow
6ac3adfa53
`Pattern` is intended to pilot some changes I would like to apply to all our sum types: - The alternatives are expressed as derived classes rather than members of a `std::variant`. - The alternatives are classes in the [style guide sense](https://google.github.io/styleguide/cppguide.html#Structs_vs._Classes), meaning they can have invariants, but can't have public data members. - Creating an object is expressed using a constructor rather than a factory function. - Accessing an alternative is expressed as a cast (using LLVM's RTTI system) rather than `std::get` or a `Get` method. Co-authored-by: Jon Meow <46229924+jonmeow@users.noreply.github.com>
100 lines
3.2 KiB
C++
100 lines
3.2 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 "executable_semantics/ast/declaration.h"
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namespace Carbon {
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auto Declaration::MakeFunctionDeclaration(FunctionDefinition definition)
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-> const Declaration {
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Declaration d;
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d.value = FunctionDeclaration({.definition = definition});
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return d;
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}
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auto Declaration::MakeStructDeclaration(int line_num, std::string name,
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std::list<Member*> members)
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-> const Declaration {
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Declaration d;
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d.value = StructDeclaration(
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{.definition = StructDefinition({.line_num = line_num,
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.name = std::move(name),
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.members = std::move(members)})});
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return d;
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}
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auto Declaration::MakeChoiceDeclaration(
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int line_num, std::string name,
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std::list<std::pair<std::string, const Expression*>> alternatives)
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-> const Declaration {
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Declaration d;
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d.value = ChoiceDeclaration({.line_num = line_num,
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.name = std::move(name),
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.alternatives = std::move(alternatives)});
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return d;
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}
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auto Declaration::MakeVariableDeclaration(int source_location,
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const BindingPattern* binding,
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const Expression* initializer)
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-> const Declaration {
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Declaration d;
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d.value = VariableDeclaration({.source_location = source_location,
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.binding = binding,
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.initializer = initializer});
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return d;
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}
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auto Declaration::GetFunctionDeclaration() const -> const FunctionDeclaration& {
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return std::get<FunctionDeclaration>(value);
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}
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auto Declaration::GetStructDeclaration() const -> const StructDeclaration& {
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return std::get<StructDeclaration>(value);
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}
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auto Declaration::GetChoiceDeclaration() const -> const ChoiceDeclaration& {
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return std::get<ChoiceDeclaration>(value);
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}
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auto Declaration::GetVariableDeclaration() const -> const VariableDeclaration& {
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return std::get<VariableDeclaration>(value);
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}
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void Declaration::Print(llvm::raw_ostream& out) const {
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switch (tag()) {
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case DeclarationKind::FunctionDeclaration:
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out << GetFunctionDeclaration().definition;
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break;
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case DeclarationKind::StructDeclaration: {
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const StructDefinition& struct_def = GetStructDeclaration().definition;
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out << "struct " << struct_def.name << " {\n";
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for (Member* m : struct_def.members) {
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out << *m;
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}
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out << "}\n";
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break;
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}
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case DeclarationKind::ChoiceDeclaration: {
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const auto& choice = GetChoiceDeclaration();
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out << "choice " << choice.name << " {\n";
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for (const auto& [name, signature] : choice.alternatives) {
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out << "alt " << name << " " << *signature << ";\n";
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}
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out << "}\n";
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break;
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}
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case DeclarationKind::VariableDeclaration: {
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const auto& var = GetVariableDeclaration();
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out << "var " << *var.binding << " = " << *var.initializer << "\n";
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break;
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}
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}
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}
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} // namespace Carbon
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