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//===- FileMatchTrie.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
//
//===----------------------------------------------------------------------===//
//
// This file implements a match trie to find the matching file in a compilation
// database based on a given path in the presence of symlinks.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_TOOLING_FILEMATCHTRIE_H
#define LLVM_CLANG_TOOLING_FILEMATCHTRIE_H
#include "clang/Basic/LLVM.h"
#include "llvm/ADT/StringRef.h"
#include <memory>
namespace clang {
namespace tooling {
class FileMatchTrieNode;
struct PathComparator {
virtual ~PathComparator() = default;
virtual bool equivalent(StringRef FileA, StringRef FileB) const = 0;
};
/// A trie to efficiently match against the entries of the compilation
/// database in order of matching suffix length.
///
/// When a clang tool is supposed to operate on a specific file, we have to
/// find the corresponding file in the compilation database. Although entries
/// in the compilation database are keyed by filename, a simple string match
/// is insufficient because of symlinks. Commonly, a project hierarchy looks
/// like this:
/// /<project-root>/src/<path>/<somefile>.cc (used as input for the tool)
/// /<project-root>/build/<symlink-to-src>/<path>/<somefile>.cc (stored in DB)
///
/// Furthermore, there might be symlinks inside the source folder or inside the
/// database, so that the same source file is translated with different build
/// options.
///
/// For a given input file, the \c FileMatchTrie finds its entries in order
/// of matching suffix length. For each suffix length, there might be one or
/// more entries in the database. For each of those entries, it calls
/// \c llvm::sys::fs::equivalent() (injected as \c PathComparator). There might
/// be zero or more entries with the same matching suffix length that are
/// equivalent to the input file. Three cases are distinguished:
/// 0 equivalent files: Continue with the next suffix length.
/// 1 equivalent file: Best match found, return it.
/// >1 equivalent files: Match is ambiguous, return error.
class FileMatchTrie {
public:
FileMatchTrie();
/// Construct a new \c FileMatchTrie with the given \c PathComparator.
///
/// The \c FileMatchTrie takes ownership of 'Comparator'. Used for testing.
FileMatchTrie(PathComparator* Comparator);
~FileMatchTrie();
/// Insert a new absolute path. Relative paths are ignored.
void insert(StringRef NewPath);
/// Finds the corresponding file in this trie.
///
/// Returns file name stored in this trie that is equivalent to 'FileName'
/// according to 'Comparator', if it can be uniquely identified. If there
/// are no matches an empty \c StringRef is returned. If there are ambiguous
/// matches, an empty \c StringRef is returned and a corresponding message
/// written to 'Error'.
StringRef findEquivalent(StringRef FileName,
raw_ostream &Error) const;
private:
FileMatchTrieNode *Root;
std::unique_ptr<PathComparator> Comparator;
};
} // namespace tooling
} // namespace clang
#endif // LLVM_CLANG_TOOLING_FILEMATCHTRIE_H
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