[clang] [clang][ssaf] Introduce entity abstraction for SSAF (PR #169131)

[Balázs Benics via cfe-commits]

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@@ -0,0 +1,84 @@
+//===- BuildNamespace.h -----------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_ANALYSIS_SCALABLE_BUILD_NAMESPACE_H
+#define LLVM_CLANG_ANALYSIS_SCALABLE_BUILD_NAMESPACE_H
+
+#include "llvm/ADT/StringRef.h"
+#include <optional>
+#include <string>
+#include <vector>
+
+namespace clang {
+namespace ssaf {
+
+enum class BuildNamespaceKind : unsigned short {
+  CompilationUnit,
+  LinkUnit
+};
+
+std::string toString(BuildNamespaceKind BNK);
+
+std::optional<BuildNamespaceKind> parseBuildNamespaceKind(llvm::StringRef Str);
+
+/// Represents a single step in the build process.
+class BuildNamespace {
+  BuildNamespaceKind Kind;
+  std::string Name;
+public:
+  BuildNamespace(BuildNamespaceKind Kind, llvm::StringRef Name)
+    : Kind(Kind), Name(Name.str()) {}
+
+  static BuildNamespace makeTU(llvm::StringRef CompilationId);
+
+  bool operator==(const BuildNamespace& Other) const;
+  bool operator!=(const BuildNamespace& Other) const;
+  bool operator<(const BuildNamespace& Other) const;
+
+  friend class SerializationFormat;
+};
+
+/// Represents a sequence of steps in the build process.
+class NestedBuildNamespace {
+  friend class SerializationFormat;
+
+  std::vector<BuildNamespace> Namespaces;
+
+public:
+  NestedBuildNamespace() = default;
+
+  explicit NestedBuildNamespace(const std::vector<BuildNamespace>& Namespaces)
+    : Namespaces(Namespaces) {}
+
+  explicit NestedBuildNamespace(const BuildNamespace& N) {
+    Namespaces.push_back(N);
+  }
+
+  static NestedBuildNamespace makeTU(llvm::StringRef CompilationId);
+
+  NestedBuildNamespace makeQualified(NestedBuildNamespace Namespace) {
+    auto Copy = *this;
+    for (const auto& N : Namespace.Namespaces)
+      Copy.Namespaces.push_back(N);
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steakhal wrote:

Could we use `llvm::append_range` here?
We know ahead of time how many elements we add. Could we reserve?

https://github.com/llvm/llvm-project/pull/169131