text: //===---------- NamespaceAliaser.cpp - clang-tidy -------------------------===//
  //
  // 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
  //
  //===----------------------------------------------------------------------===//
  
  #include "NamespaceAliaser.h"
  
  #include "ASTUtils.h"
  #include "clang/ASTMatchers/ASTMatchFinder.h"
  #include "clang/ASTMatchers/ASTMatchers.h"
  #include "clang/Lex/Lexer.h"
  namespace clang {
  namespace tidy {
  namespace utils {
  
  using namespace ast_matchers;
  
  NamespaceAliaser::NamespaceAliaser(const SourceManager &SourceMgr)
      : SourceMgr(SourceMgr) {}
  
  AST_MATCHER_P(NamespaceAliasDecl, hasTargetNamespace,
                ast_matchers::internal::Matcher<NamespaceDecl>, innerMatcher) {
    return innerMatcher.matches(*Node.getNamespace(), Finder, Builder);
  }
  
  Optional<FixItHint>
  NamespaceAliaser::createAlias(ASTContext &Context, const Stmt &Statement,
                                StringRef Namespace,
                                const std::vector<std::string> &Abbreviations) {
    const FunctionDecl *Function = getSurroundingFunction(Context, Statement);
    if (!Function || !Function->hasBody())
      return None;
  
    if (AddedAliases[Function].count(Namespace.str()) != 0)
      return None;
  
    // FIXME: Doesn't consider the order of declarations.
    // If we accidentally pick an alias defined later in the function,
    // the output won't compile.
    // FIXME: Also doesn't consider file or class-scope aliases.
  
    const auto *ExistingAlias = selectFirst<NamedDecl>(
        "alias", match(functionDecl(hasBody(compoundStmt(has(declStmt(
                           has(namespaceAliasDecl(hasTargetNamespace(hasName(
                                                      std::string(Namespace))))
                                   .bind("alias"))))))),
                       *Function, Context));
  
    if (ExistingAlias != nullptr) {
      AddedAliases[Function][Namespace.str()] = ExistingAlias->getName().str();
      return None;
    }
  
    for (const auto &Abbreviation : Abbreviations) {
      DeclarationMatcher ConflictMatcher = namedDecl(hasName(Abbreviation));
      const auto HasConflictingChildren =
          !match(findAll(ConflictMatcher), *Function, Context).empty();
      const auto HasConflictingAncestors =
          !match(functionDecl(hasAncestor(decl(has(ConflictMatcher)))), *Function,
                 Context)
               .empty();
      if (HasConflictingAncestors || HasConflictingChildren)
        continue;
  
      std::string Declaration =
          (llvm::Twine("\nnamespace ") + Abbreviation + " = " + Namespace + ";")
              .str();
      SourceLocation Loc =
          Lexer::getLocForEndOfToken(Function->getBody()->getBeginLoc(), 0,
                                     SourceMgr, Context.getLangOpts());
      AddedAliases[Function][Namespace.str()] = Abbreviation;
      return FixItHint::CreateInsertion(Loc, Declaration);
    }
  
    return None;
  }
  
  std::string NamespaceAliaser::getNamespaceName(ASTContext &Context,
                                                 const Stmt &Statement,
                                                 StringRef Namespace) const {
    const auto *Function = getSurroundingFunction(Context, Statement);
    auto FunctionAliases = AddedAliases.find(Function);
    if (FunctionAliases != AddedAliases.end()) {
      if (FunctionAliases->second.count(Namespace) != 0) {
        return FunctionAliases->second.find(Namespace)->getValue();
      }
    }
    return Namespace.str();
  }
  
  } // namespace utils
  } // namespace tidy
  } // namespace clang
  