119 lines · cpp
1//===--- HeaderAnalysis.cpp -------------------------------------*- C++ -*-===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "clang/Tooling/Inclusions/HeaderAnalysis.h"10#include "clang/Basic/SourceLocation.h"11#include "clang/Lex/HeaderSearch.h"12 13namespace clang::tooling {14namespace {15 16// Is Line an #if or #ifdef directive?17// FIXME: This makes headers with #ifdef LINUX/WINDOWS/MACOS marked as non18// self-contained and is probably not what we want.19bool isIf(llvm::StringRef Line) {20 Line = Line.ltrim();21 if (!Line.consume_front("#"))22 return false;23 Line = Line.ltrim();24 return Line.starts_with("if");25}26 27// Is Line an #error directive mentioning includes?28bool isErrorAboutInclude(llvm::StringRef Line) {29 Line = Line.ltrim();30 if (!Line.consume_front("#"))31 return false;32 Line = Line.ltrim();33 if (!Line.starts_with("error"))34 return false;35 return Line.contains_insensitive(36 "includ"); // Matches "include" or "including".37}38 39// Heuristically headers that only want to be included via an umbrella.40bool isDontIncludeMeHeader(StringRef Content) {41 llvm::StringRef Line;42 // Only sniff up to 100 lines or 10KB.43 Content = Content.take_front(100 * 100);44 for (unsigned I = 0; I < 100 && !Content.empty(); ++I) {45 std::tie(Line, Content) = Content.split('\n');46 if (isIf(Line) && isErrorAboutInclude(Content.split('\n').first))47 return true;48 }49 return false;50}51 52bool isImportLine(llvm::StringRef Line) {53 Line = Line.ltrim();54 if (!Line.consume_front("#"))55 return false;56 Line = Line.ltrim();57 return Line.starts_with("import");58}59 60llvm::StringRef getFileContents(FileEntryRef FE, const SourceManager &SM) {61 return const_cast<SourceManager &>(SM)62 .getMemoryBufferForFileOrNone(FE)63 .value_or(llvm::MemoryBufferRef())64 .getBuffer();65}66 67} // namespace68 69bool isSelfContainedHeader(FileEntryRef FE, const SourceManager &SM,70 const HeaderSearch &HeaderInfo) {71 if (!HeaderInfo.isFileMultipleIncludeGuarded(FE) &&72 !HeaderInfo.hasFileBeenImported(FE) &&73 // Any header that contains #imports is supposed to be #import'd so no74 // need to check for anything but the main-file.75 (SM.getFileEntryForID(SM.getMainFileID()) != FE ||76 !codeContainsImports(getFileContents(FE, SM))))77 return false;78 // This pattern indicates that a header can't be used without79 // particular preprocessor state, usually set up by another header.80 return !isDontIncludeMeHeader(getFileContents(FE, SM));81}82 83bool codeContainsImports(llvm::StringRef Code) {84 // Only sniff up to 100 lines or 10KB.85 Code = Code.take_front(100 * 100);86 llvm::StringRef Line;87 for (unsigned I = 0; I < 100 && !Code.empty(); ++I) {88 std::tie(Line, Code) = Code.split('\n');89 if (isImportLine(Line))90 return true;91 }92 return false;93}94 95std::optional<StringRef> parseIWYUPragma(const char *Text) {96 // Skip the comment start, // or /*.97 if (Text[0] != '/' || (Text[1] != '/' && Text[1] != '*'))98 return std::nullopt;99 bool BlockComment = Text[1] == '*';100 Text += 2;101 102 // Per spec, direcitves are whitespace- and case-sensitive.103 constexpr llvm::StringLiteral IWYUPragma = " IWYU pragma: ";104 if (strncmp(Text, IWYUPragma.data(), IWYUPragma.size()))105 return std::nullopt;106 Text += IWYUPragma.size();107 const char *End = Text;108 while (*End != 0 && *End != '\n')109 ++End;110 StringRef Rest(Text, End - Text);111 // Strip off whitespace and comment markers to avoid confusion. This isn't112 // fully-compatible with IWYU, which splits into whitespace-delimited tokens.113 if (BlockComment)114 Rest.consume_back("*/");115 return Rest.trim();116}117 118} // namespace clang::tooling119