mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-27 20:00:10 +01:00
Richard Smith
782bd87316
This is intended to be used for template instantiation, but for now takes no stance as to what it's cloning. This is tested by parsing and cloning all of our test files, and checking that the result of converting each AST to proto is the same as the result of cloning and then converting each AST to proto.
94 lines
3.4 KiB
C++
94 lines
3.4 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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#ifndef CARBON_EXPLORER_AST_AST_NODE_H_
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#define CARBON_EXPLORER_AST_AST_NODE_H_
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#include "explorer/ast/ast_rtti.h"
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#include "explorer/common/source_location.h"
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#include "llvm/Support/Casting.h"
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namespace Carbon {
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class CloneContext;
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// Base class for all nodes in the AST.
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//
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// Every class derived from this class must be listed in ast_rtti.txt. See
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// the documentation of gen_rtti.py for details about the format. As a result,
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// every abstract class `Foo` will have a `FooKind` enumerated type, whose
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// enumerators correspond to the subclasses of `Foo`.
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//
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// AstNode and its derived classes support LLVM-style RTTI, including
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// llvm::isa, llvm::cast, and llvm::dyn_cast. To support this, every
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// class derived from Declaration must provide a `classof` operation, with
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// the following form, where `Foo` is the name of the derived class:
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//
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// static auto classof(const AstNode* node) -> bool {
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// return InheritsFromFoo(node->kind());
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// }
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//
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// Furthermore, if the class is abstract, it must provide a `kind()` operation,
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// with the following form:
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//
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// auto kind() const -> FooKind { return static_cast<FooKind>(root_kind()); }
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//
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// The definitions of `InheritsFromFoo` and `FooKind` are generated from
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// ast_rtti.txt, and are implicitly provided by this header.
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//
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// Every AST node is expected to provide a cloning constructor:
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//
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// explicit MyAstNode(CloneContext& context, const MyAstNode& other);
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//
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// The cloning constructor should behave like a copy constructor, but pointers
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// to other AST nodes should be passed through context.Clone to clone the
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// referenced object.
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//
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// TODO: To support generic traversal, add children() method, and ensure that
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// all AstNodes are reachable from a root AstNode.
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class AstNode {
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public:
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AstNode(AstNode&&) = delete;
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auto operator=(AstNode&&) -> AstNode& = delete;
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virtual ~AstNode() = 0;
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// Print the AST rooted at the node.
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virtual void Print(llvm::raw_ostream& out) const = 0;
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// Print identifying information about the node, such as its name.
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virtual void PrintID(llvm::raw_ostream& out) const = 0;
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LLVM_DUMP_METHOD void Dump() const { Print(llvm::errs()); }
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// Returns an enumerator specifying the concrete type of this node.
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//
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// Abstract subclasses of AstNode will provide their own `kind()` method
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// which hides this one, and provides a narrower return type.
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auto kind() const -> AstNodeKind { return kind_; }
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// The location of the code described by this node.
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auto source_loc() const -> SourceLocation { return source_loc_; }
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protected:
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// Constructs an AstNode representing code at the given location. `kind`
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// must be the enumerator that exactly matches the concrete type being
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// constructed.
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explicit AstNode(AstNodeKind kind, SourceLocation source_loc)
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: kind_(kind), source_loc_(source_loc) {}
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// Clone this AstNode.
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explicit AstNode(CloneContext& /*context*/, const AstNode& other)
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: kind_(other.kind_), source_loc_(other.source_loc_) {}
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// Equivalent to kind(), but will not be hidden by `kind()` methods of
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// derived classes.
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auto root_kind() const -> AstNodeKind { return kind_; }
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private:
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AstNodeKind kind_;
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SourceLocation source_loc_;
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};
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} // namespace Carbon
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#endif // CARBON_EXPLORER_AST_AST_NODE_H_
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