[LLDB] Added syntax highlighting support

Summary:
This patch adds syntax highlighting support to LLDB. When enabled (and lldb is allowed
to use colors), printed source code is annotated with the ANSI color escape sequences.

So far we have only one highlighter which is based on Clang and is responsible for all
languages that are supported by Clang. It essentially just runs the raw lexer over the input
and then surrounds the specific tokens with the configured escape sequences.

Reviewers: zturner, davide

Reviewed By: davide

Subscribers: labath, teemperor, llvm-commits, mgorny, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D49334

llvm-svn: 338662

1 files changed, 227 insertions, 0 deletions

diff --git a/lldb/source/Plugins/Language/ClangCommon/ClangHighlighter.cpp b/lldb/source/Plugins/Language/ClangCommon/ClangHighlighter.cpp
new file mode 100644
index 00000000000..29da03d71dd
--- /dev/null
+++ b/lldb/source/Plugins/Language/ClangCommon/ClangHighlighter.cpp
@@ -0,0 +1,227 @@
+//===-- ClangHighlighter.cpp ------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ClangHighlighter.h"
+
+#include "lldb/Target/Language.h"
+#include "lldb/Utility/AnsiTerminal.h"
+#include "lldb/Utility/StreamString.h"
+
+#include "clang/Basic/SourceManager.h"
+#include "clang/Lex/Lexer.h"
+#include "llvm/ADT/StringSet.h"
+#include "llvm/Support/MemoryBuffer.h"
+
+using namespace lldb_private;
+
+bool ClangHighlighter::isKeyword(llvm::StringRef token) const {
+  return keywords.find(token) != keywords.end();
+}
+
+ClangHighlighter::ClangHighlighter() {
+#define KEYWORD(X, N) keywords.insert(#X);
+#include "clang/Basic/TokenKinds.def"
+}
+
+/// Determines which style should be applied to the given token.
+/// \param highlighter
+///     The current highlighter that should use the style.
+/// \param token
+///     The current token.
+/// \param tok_str
+///     The string in the source code the token represents.
+/// \param options
+///     The style we use for coloring the source code.
+/// \param in_pp_directive
+///     If we are currently in a preprocessor directive. NOTE: This is
+///     passed by reference and will be updated if the current token starts
+///     or ends a preprocessor directive.
+/// \return
+///     The ColorStyle that should be applied to the token.
+static HighlightStyle::ColorStyle
+determineClangStyle(const ClangHighlighter &highlighter,
+                    const clang::Token &token, llvm::StringRef tok_str,
+                    const HighlightStyle &options, bool &in_pp_directive) {
+  using namespace clang;
+
+  if (token.is(tok::comment)) {
+    // If we were in a preprocessor directive before, we now left it.
+    in_pp_directive = false;
+    return options.comment;
+  } else if (in_pp_directive || token.getKind() == tok::hash) {
+    // Let's assume that the rest of the line is a PP directive.
+    in_pp_directive = true;
+    // Preprocessor directives are hard to match, so we have to hack this in.
+    return options.pp_directive;
+  } else if (tok::isStringLiteral(token.getKind()))
+    return options.string_literal;
+  else if (tok::isLiteral(token.getKind()))
+    return options.scalar_literal;
+  else if (highlighter.isKeyword(tok_str))
+    return options.keyword;
+  else
+    switch (token.getKind()) {
+    case tok::raw_identifier:
+    case tok::identifier:
+      return options.identifier;
+    case tok::l_brace:
+    case tok::r_brace:
+      return options.braces;
+    case tok::l_square:
+    case tok::r_square:
+      return options.square_brackets;
+    case tok::l_paren:
+    case tok::r_paren:
+      return options.parentheses;
+    case tok::comma:
+      return options.comma;
+    case tok::coloncolon:
+    case tok::colon:
+      return options.colon;
+
+    case tok::amp:
+    case tok::ampamp:
+    case tok::ampequal:
+    case tok::star:
+    case tok::starequal:
+    case tok::plus:
+    case tok::plusplus:
+    case tok::plusequal:
+    case tok::minus:
+    case tok::arrow:
+    case tok::minusminus:
+    case tok::minusequal:
+    case tok::tilde:
+    case tok::exclaim:
+    case tok::exclaimequal:
+    case tok::slash:
+    case tok::slashequal:
+    case tok::percent:
+    case tok::percentequal:
+    case tok::less:
+    case tok::lessless:
+    case tok::lessequal:
+    case tok::lesslessequal:
+    case tok::spaceship:
+    case tok::greater:
+    case tok::greatergreater:
+    case tok::greaterequal:
+    case tok::greatergreaterequal:
+    case tok::caret:
+    case tok::caretequal:
+    case tok::pipe:
+    case tok::pipepipe:
+    case tok::pipeequal:
+    case tok::question:
+    case tok::equal:
+    case tok::equalequal:
+      return options.operators;
+    default:
+      break;
+    }
+  return HighlightStyle::ColorStyle();
+}
+
+std::size_t ClangHighlighter::Highlight(const HighlightStyle &options,
+                                        llvm::StringRef line,
+                                        llvm::StringRef previous_lines,
+                                        Stream &result) const {
+  using namespace clang;
+
+  std::size_t written_bytes = 0;
+
+  FileSystemOptions file_opts;
+  FileManager file_mgr(file_opts);
+
+  unsigned line_number = previous_lines.count('\n') + 1U;
+
+  // Let's build the actual source code Clang needs and setup some utility
+  // objects.
+  std::string full_source = previous_lines.str() + line.str();
+  llvm::IntrusiveRefCntPtr<DiagnosticIDs> diag_ids(new DiagnosticIDs());
+  llvm::IntrusiveRefCntPtr<DiagnosticOptions> diags_opts(
+      new DiagnosticOptions());
+  DiagnosticsEngine diags(diag_ids, diags_opts);
+  clang::SourceManager SM(diags, file_mgr);
+  auto buf = llvm::MemoryBuffer::getMemBuffer(full_source);
+
+  FileID FID = SM.createFileID(clang::SourceManager::Unowned, buf.get());
+
+  // Let's just enable the latest ObjC and C++ which should get most tokens
+  // right.
+  LangOptions Opts;
+  Opts.ObjC2 = true;
+  Opts.CPlusPlus17 = true;
+  Opts.LineComment = true;
+
+  Lexer lex(FID, buf.get(), SM, Opts);
+  // The lexer should keep whitespace around.
+  lex.SetKeepWhitespaceMode(true);
+
+  // Keeps track if we have entered a PP directive.
+  bool in_pp_directive = false;
+
+  // True once we actually lexed the user provided line.
+  bool found_user_line = false;
+
+  Token token;
+  bool exit = false;
+  while (!exit) {
+    // Returns true if this is the last token we get from the lexer.
+    exit = lex.LexFromRawLexer(token);
+
+    bool invalid = false;
+    unsigned current_line_number =
+        SM.getSpellingLineNumber(token.getLocation(), &invalid);
+    if (current_line_number != line_number)
+      continue;
+    found_user_line = true;
+
+    // We don't need to print any tokens without a spelling line number.
+    if (invalid)
+      continue;
+
+    // Same as above but with the column number.
+    invalid = false;
+    unsigned start = SM.getSpellingColumnNumber(token.getLocation(), &invalid);
+    if (invalid)
+      continue;
+    // Column numbers start at 1, but indexes in our string start at 0.
+    --start;
+
+    // Annotations don't have a length, so let's skip them.
+    if (token.isAnnotation())
+      continue;
+
+    // Extract the token string from our source code.
+    llvm::StringRef tok_str = line.substr(start, token.getLength());
+
+    // If the token is just an empty string, we can skip all the work below.
+    if (tok_str.empty())
+      continue;
+
+    // See how we are supposed to highlight this token.
+    HighlightStyle::ColorStyle color =
+        determineClangStyle(*this, token, tok_str, options, in_pp_directive);
+
+    written_bytes += color.Apply(result, tok_str);
+  }
+
+  // If we went over the whole file but couldn't find our own file, then
+  // somehow our setup was wrong. When we're in release mode we just give the
+  // user the normal line and pretend we don't know how to highlight it. In
+  // debug mode we bail out with an assert as this should never happen.
+  if (!found_user_line) {
+    result << line;
+    written_bytes += line.size();
+    assert(false && "We couldn't find the user line in the input file?");
+  }
+
+  return written_bytes;
+}