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59 lines
2.1 KiB
C++
59 lines
2.1 KiB
C++
//===--- ConstraintGraphScope.h - Constraint Graph Scope --------*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the \c ConstraintGraphScope class, an RAII object that
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// introduces a new scope in which changes to the constraint graph are
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// capture and will be reverted when the scope disappears.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_SEMA_CONSTRAINT_GRAPH_SCOPE_H
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#define SWIFT_SEMA_CONSTRAINT_GRAPH_SCOPE_H
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namespace swift {
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namespace constraints {
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class ConstraintGraph;
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/// RAII object that introduces a new constraint graph scope to capture
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/// modifications made to the constraint graph.
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///
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/// Scopes are arranged in a stack, where the active scope is the top of the
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/// stack. All changes made to the constraint graph are recorded in the
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/// active scope. When the scope is popped (via the RAII object destructor),
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/// those changes are reverted.
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class ConstraintGraphScope {
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ConstraintGraph &CG;
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/// The parent scope, or null if this is the topmost scope.
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ConstraintGraphScope *ParentScope;
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/// The number of recorded changes that existed at the time this scope was
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/// formed.
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///
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/// When this scope exits, any changes beyond this will be reverted to
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/// bring the graph back to its state prior to the introduction of this
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/// variable.
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unsigned NumChanges;
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ConstraintGraphScope(const ConstraintGraphScope&) = delete;
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ConstraintGraphScope &operator=(const ConstraintGraphScope&) = delete;
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public:
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explicit ConstraintGraphScope(ConstraintGraph &CG);
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~ConstraintGraphScope();
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};
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} // end namespace constraints
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} // end namespace swift
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#endif // LLVM_SWIFT_SEMA_CONSTRAINT_GRAPH_SCOPE_H
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