1//===-- ClangHighlighter.cpp ----------------------------------------------===//
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-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "ClangHighlighter.h"
10
11#include "lldb/Host/FileSystem.h"
12#include "lldb/Target/Language.h"
13#include "lldb/Utility/AnsiTerminal.h"
14#include "lldb/Utility/StreamString.h"
15
16#include "clang/Basic/FileManager.h"
17#include "clang/Basic/SourceManager.h"
18#include "clang/Lex/Lexer.h"
19#include "llvm/ADT/StringSet.h"
20#include "llvm/Support/MemoryBuffer.h"
21
22using namespace lldb_private;
23
24bool ClangHighlighter::isKeyword(llvm::StringRef token) const {
25  return keywords.find(token) != keywords.end();
26}
27
28ClangHighlighter::ClangHighlighter() {
29#define KEYWORD(X, N) keywords.insert(#X);
30#include "clang/Basic/TokenKinds.def"
31}
32
33/// Determines which style should be applied to the given token.
34/// \param highlighter
35///     The current highlighter that should use the style.
36/// \param token
37///     The current token.
38/// \param tok_str
39///     The string in the source code the token represents.
40/// \param options
41///     The style we use for coloring the source code.
42/// \param in_pp_directive
43///     If we are currently in a preprocessor directive. NOTE: This is
44///     passed by reference and will be updated if the current token starts
45///     or ends a preprocessor directive.
46/// \return
47///     The ColorStyle that should be applied to the token.
48static HighlightStyle::ColorStyle
49determineClangStyle(const ClangHighlighter &highlighter,
50                    const clang::Token &token, llvm::StringRef tok_str,
51                    const HighlightStyle &options, bool &in_pp_directive) {
52  using namespace clang;
53
54  if (token.is(tok::comment)) {
55    // If we were in a preprocessor directive before, we now left it.
56    in_pp_directive = false;
57    return options.comment;
58  } else if (in_pp_directive || token.getKind() == tok::hash) {
59    // Let's assume that the rest of the line is a PP directive.
60    in_pp_directive = true;
61    // Preprocessor directives are hard to match, so we have to hack this in.
62    return options.pp_directive;
63  } else if (tok::isStringLiteral(token.getKind()))
64    return options.string_literal;
65  else if (tok::isLiteral(token.getKind()))
66    return options.scalar_literal;
67  else if (highlighter.isKeyword(tok_str))
68    return options.keyword;
69  else
70    switch (token.getKind()) {
71    case tok::raw_identifier:
72    case tok::identifier:
73      return options.identifier;
74    case tok::l_brace:
75    case tok::r_brace:
76      return options.braces;
77    case tok::l_square:
78    case tok::r_square:
79      return options.square_brackets;
80    case tok::l_paren:
81    case tok::r_paren:
82      return options.parentheses;
83    case tok::comma:
84      return options.comma;
85    case tok::coloncolon:
86    case tok::colon:
87      return options.colon;
88
89    case tok::amp:
90    case tok::ampamp:
91    case tok::ampequal:
92    case tok::star:
93    case tok::starequal:
94    case tok::plus:
95    case tok::plusplus:
96    case tok::plusequal:
97    case tok::minus:
98    case tok::arrow:
99    case tok::minusminus:
100    case tok::minusequal:
101    case tok::tilde:
102    case tok::exclaim:
103    case tok::exclaimequal:
104    case tok::slash:
105    case tok::slashequal:
106    case tok::percent:
107    case tok::percentequal:
108    case tok::less:
109    case tok::lessless:
110    case tok::lessequal:
111    case tok::lesslessequal:
112    case tok::spaceship:
113    case tok::greater:
114    case tok::greatergreater:
115    case tok::greaterequal:
116    case tok::greatergreaterequal:
117    case tok::caret:
118    case tok::caretequal:
119    case tok::pipe:
120    case tok::pipepipe:
121    case tok::pipeequal:
122    case tok::question:
123    case tok::equal:
124    case tok::equalequal:
125      return options.operators;
126    default:
127      break;
128    }
129  return HighlightStyle::ColorStyle();
130}
131
132void ClangHighlighter::Highlight(const HighlightStyle &options,
133                                 llvm::StringRef line,
134                                 llvm::Optional<size_t> cursor_pos,
135                                 llvm::StringRef previous_lines,
136                                 Stream &result) const {
137  using namespace clang;
138
139  FileSystemOptions file_opts;
140  FileManager file_mgr(file_opts,
141                       FileSystem::Instance().GetVirtualFileSystem());
142
143  // The line might end in a backslash which would cause Clang to drop the
144  // backslash and the terminating new line. This makes sense when parsing C++,
145  // but when highlighting we care about preserving the backslash/newline. To
146  // not lose this information we remove the new line here so that Clang knows
147  // this is just a single line we are highlighting. We add back the newline
148  // after tokenizing.
149  llvm::StringRef line_ending = "";
150  // There are a few legal line endings Clang recognizes and we need to
151  // temporarily remove from the string.
152  if (line.consume_back("\r\n"))
153    line_ending = "\r\n";
154  else if (line.consume_back("\n"))
155    line_ending = "\n";
156  else if (line.consume_back("\r"))
157    line_ending = "\r";
158
159  unsigned line_number = previous_lines.count('\n') + 1U;
160
161  // Let's build the actual source code Clang needs and setup some utility
162  // objects.
163  std::string full_source = previous_lines.str() + line.str();
164  llvm::IntrusiveRefCntPtr<DiagnosticIDs> diag_ids(new DiagnosticIDs());
165  llvm::IntrusiveRefCntPtr<DiagnosticOptions> diags_opts(
166      new DiagnosticOptions());
167  DiagnosticsEngine diags(diag_ids, diags_opts);
168  clang::SourceManager SM(diags, file_mgr);
169  auto buf = llvm::MemoryBuffer::getMemBuffer(full_source);
170
171  FileID FID = SM.createFileID(clang::SourceManager::Unowned, buf.get());
172
173  // Let's just enable the latest ObjC and C++ which should get most tokens
174  // right.
175  LangOptions Opts;
176  Opts.ObjC = true;
177  // FIXME: This should probably set CPlusPlus, CPlusPlus11, ... too
178  Opts.CPlusPlus17 = true;
179  Opts.LineComment = true;
180
181  Lexer lex(FID, buf.get(), SM, Opts);
182  // The lexer should keep whitespace around.
183  lex.SetKeepWhitespaceMode(true);
184
185  // Keeps track if we have entered a PP directive.
186  bool in_pp_directive = false;
187
188  // True once we actually lexed the user provided line.
189  bool found_user_line = false;
190
191  // True if we already highlighted the token under the cursor, false otherwise.
192  bool highlighted_cursor = false;
193  Token token;
194  bool exit = false;
195  while (!exit) {
196    // Returns true if this is the last token we get from the lexer.
197    exit = lex.LexFromRawLexer(token);
198
199    bool invalid = false;
200    unsigned current_line_number =
201        SM.getSpellingLineNumber(token.getLocation(), &invalid);
202    if (current_line_number != line_number)
203      continue;
204    found_user_line = true;
205
206    // We don't need to print any tokens without a spelling line number.
207    if (invalid)
208      continue;
209
210    // Same as above but with the column number.
211    invalid = false;
212    unsigned start = SM.getSpellingColumnNumber(token.getLocation(), &invalid);
213    if (invalid)
214      continue;
215    // Column numbers start at 1, but indexes in our string start at 0.
216    --start;
217
218    // Annotations don't have a length, so let's skip them.
219    if (token.isAnnotation())
220      continue;
221
222    // Extract the token string from our source code.
223    llvm::StringRef tok_str = line.substr(start, token.getLength());
224
225    // If the token is just an empty string, we can skip all the work below.
226    if (tok_str.empty())
227      continue;
228
229    // If the cursor is inside this token, we have to apply the 'selected'
230    // highlight style before applying the actual token color.
231    llvm::StringRef to_print = tok_str;
232    StreamString storage;
233    auto end = start + token.getLength();
234    if (cursor_pos && end > *cursor_pos && !highlighted_cursor) {
235      highlighted_cursor = true;
236      options.selected.Apply(storage, tok_str);
237      to_print = storage.GetString();
238    }
239
240    // See how we are supposed to highlight this token.
241    HighlightStyle::ColorStyle color =
242        determineClangStyle(*this, token, tok_str, options, in_pp_directive);
243
244    color.Apply(result, to_print);
245  }
246
247  // Add the line ending we trimmed before tokenizing.
248  result << line_ending;
249
250  // If we went over the whole file but couldn't find our own file, then
251  // somehow our setup was wrong. When we're in release mode we just give the
252  // user the normal line and pretend we don't know how to highlight it. In
253  // debug mode we bail out with an assert as this should never happen.
254  if (!found_user_line) {
255    result << line;
256    assert(false && "We couldn't find the user line in the input file?");
257  }
258}
259