tools/gn/label.cc

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "tools/gn/label.h"
   6
   7 #include "base/logging.h"
   8 #include "base/strings/string_util.h"
   9 #include "tools/gn/err.h"
  10 #include "tools/gn/filesystem_utils.h"
  11 #include "tools/gn/parse_tree.h"
  12 #include "tools/gn/value.h"
  13
  14 namespace {
  15
  16 // We print user visible label names with no trailing slash after the
  17 // directory name.
  18 std::string DirWithNoTrailingSlash(const SourceDir& dir) {
  19   // Be careful not to trim if the input is just "/" or "//".
  20   if (dir.value().size() > 2)
  21     return dir.value().substr(0, dir.value().size() - 1);
  22   return dir.value();
  23 }
  24
  25 // Given the separate-out input (everything before the colon) in the dep rule,
  26 // computes the final build rule. Sets err on failure. On success,
  27 // |*used_implicit| will be set to whether the implicit current directory was
  28 // used. The value is used only for generating error messages.
  29 bool ComputeBuildLocationFromDep(const Value& input_value,
  30                                  const SourceDir& current_dir,
  31                                  const base::StringPiece& input,
  32                                  SourceDir* result,
  33                                  Err* err) {
  34   // No rule, use the current location.
  35   if (input.empty()) {
  36     *result = current_dir;
  37     return true;
  38   }
  39
  40   *result = current_dir.ResolveRelativeDir(input);
  41   return true;
  42 }
  43
  44 // Given the separated-out target name (after the colon) computes the final
  45 // name, using the implicit name from the previously-generated
  46 // computed_location if necessary. The input_value is used only for generating
  47 // error messages.
  48 bool ComputeTargetNameFromDep(const Value& input_value,
  49                               const SourceDir& computed_location,
  50                               const base::StringPiece& input,
  51                               std::string* result,
  52                               Err* err) {
  53   if (!input.empty()) {
  54     // Easy case: input is specified, just use it.
  55     result->assign(input.data(), input.size());
  56     return true;
  57   }
  58
  59   const std::string& loc = computed_location.value();
  60
  61   // Use implicit name. The path will be "//", "//base/", "//base/i18n/", etc.
  62   if (loc.size() <= 2) {
  63     *err = Err(input_value, "This dependency name is empty");
  64     return false;
  65   }
  66
  67   size_t next_to_last_slash = loc.rfind('/', loc.size() - 2);
  68   DCHECK(next_to_last_slash != std::string::npos);
  69   result->assign(&loc[next_to_last_slash + 1],
  70                  loc.size() - next_to_last_slash - 2);
  71   return true;
  72 }
  73
  74 // The original value is used only for error reporting, use the |input| as the
  75 // input to this function (which may be a substring of the original value when
  76 // we're parsing toolchains.
  77 //
  78 // If the output toolchain vars are NULL, then we'll report an error if we
  79 // find a toolchain specified (this is used when recursively parsing toolchain
  80 // labels which themselves can't have toolchain specs).
  81 //
  82 // We assume that the output variables are initialized to empty so we don't
  83 // write them unless we need them to contain something.
  84 //
  85 // Returns true on success. On failure, the out* variables might be written to
  86 // but shouldn't be used.
  87 bool Resolve(const SourceDir& current_dir,
  88              const Label& current_toolchain,
  89              const Value& original_value,
  90              const base::StringPiece& input,
  91              SourceDir* out_dir,
  92              std::string* out_name,
  93              SourceDir* out_toolchain_dir,
  94              std::string* out_toolchain_name,
  95              Err* err) {
  96   // To workaround the problem that StringPiece operator[] doesn't return a ref.
  97   const char* input_str = input.data();
  98   size_t offset = 0;
  99 #if defined(OS_WIN)
 100   if (IsPathAbsolute(input)) {
 101     if (input[0] != '/') {
 102       *err = Err(original_value, "Bad absolute path.",
 103                  "Absolute paths must be of the form /C:\\ but this is \"" +
 104                      input.as_string() + "\".");
 105       return false;
 106     }
 107     if (input.size() > 3 && input[2] == ':' && IsSlash(input[3]) &&
 108         IsAsciiAlpha(input[1])) {
 109       // Skip over the drive letter colon.
 110       offset = 3;
 111     }
 112   }
 113 #endif
 114   size_t path_separator = input.find_first_of(":(", offset);
 115   base::StringPiece location_piece;
 116   base::StringPiece name_piece;
 117   base::StringPiece toolchain_piece;
 118   if (path_separator == std::string::npos) {
 119     location_piece = input;
 120     // Leave name & toolchain piece null.
 121   } else {
 122     location_piece = base::StringPiece(&input_str[0], path_separator);
 123
 124     size_t toolchain_separator = input.find('(', path_separator);
 125     if (toolchain_separator == std::string::npos) {
 126       name_piece = base::StringPiece(&input_str[path_separator + 1],
 127                                      input.size() - path_separator - 1);
 128       // Leave location piece null.
 129     } else if (!out_toolchain_dir) {
 130       // Toolchain specified but not allows in this context.
 131       *err = Err(original_value, "Toolchain has a toolchain.",
 132           "Your toolchain definition (inside the parens) seems to itself "
 133           "have a\ntoolchain. Don't do this.");
 134       return false;
 135     } else {
 136       // Name piece is everything between the two separators. Note that the
 137       // separators may be the same (e.g. "//foo(bar)" which means empty name.
 138       if (toolchain_separator > path_separator) {
 139         name_piece = base::StringPiece(
 140             &input_str[path_separator + 1],
 141             toolchain_separator - path_separator - 1);
 142       }
 143
 144       // Toolchain name should end in a ) and this should be the end of the
 145       // string.
 146       if (input[input.size() - 1] != ')') {
 147         *err = Err(original_value, "Bad toolchain name.",
 148             "Toolchain name must end in a \")\" at the end of the label.");
 149         return false;
 150       }
 151
 152       // Subtract off the two parens to just get the toolchain name.
 153       toolchain_piece = base::StringPiece(
 154           &input_str[toolchain_separator + 1],
 155           input.size() - toolchain_separator - 2);
 156     }
 157   }
 158
 159   // Everything before the separator is the filename.
 160   // We allow three cases:
 161   //   Absolute:                "//foo:bar" -> /foo:bar
 162   //   Target in current file:  ":foo"     -> <currentdir>:foo
 163   //   Path with implicit name: "/foo"     -> /foo:foo
 164   if (location_piece.empty() && name_piece.empty()) {
 165     // Can't use both implicit filename and name (":").
 166     *err = Err(original_value, "This doesn't specify a dependency.");
 167     return false;
 168   }
 169
 170   if (!ComputeBuildLocationFromDep(original_value, current_dir, location_piece,
 171                                    out_dir, err))
 172     return false;
 173
 174   if (!ComputeTargetNameFromDep(original_value, *out_dir, name_piece,
 175                                 out_name, err))
 176     return false;
 177
 178   // Last, do the toolchains.
 179   if (out_toolchain_dir) {
 180     // Handle empty toolchain strings. We don't allow normal labels to be
 181     // empty so we can't allow the recursive call of this function to do this
 182     // check.
 183     if (toolchain_piece.empty()) {
 184       *out_toolchain_dir = current_toolchain.dir();
 185       *out_toolchain_name = current_toolchain.name();
 186       return true;
 187     } else {
 188       return Resolve(current_dir, current_toolchain, original_value,
 189                      toolchain_piece, out_toolchain_dir, out_toolchain_name,
 190                      nullptr, nullptr, err);
 191     }
 192   }
 193   return true;
 194 }
 195
 196 }  // namespace
 197
 198 Label::Label() {
 199 }
 200
 201 Label::Label(const SourceDir& dir,
 202              const base::StringPiece& name,
 203              const SourceDir& toolchain_dir,
 204              const base::StringPiece& toolchain_name)
 205     : dir_(dir),
 206       toolchain_dir_(toolchain_dir) {
 207   name_.assign(name.data(), name.size());
 208   toolchain_name_.assign(toolchain_name.data(), toolchain_name.size());
 209 }
 210
 211 Label::Label(const SourceDir& dir, const base::StringPiece& name)
 212     : dir_(dir) {
 213   name_.assign(name.data(), name.size());
 214 }
 215
 216 Label::~Label() {
 217 }
 218
 219 // static
 220 Label Label::Resolve(const SourceDir& current_dir,
 221                      const Label& current_toolchain,
 222                      const Value& input,
 223                      Err* err) {
 224   Label ret;
 225   if (input.type() != Value::STRING) {
 226     *err = Err(input, "Dependency is not a string.");
 227     return ret;
 228   }
 229   const std::string& input_string = input.string_value();
 230   if (input_string.empty()) {
 231     *err = Err(input, "Dependency string is empty.");
 232     return ret;
 233   }
 234
 235   if (!::Resolve(current_dir, current_toolchain, input, input_string,
 236                  &ret.dir_, &ret.name_,
 237                  &ret.toolchain_dir_, &ret.toolchain_name_,
 238                  err))
 239     return Label();
 240   return ret;
 241 }
 242
 243 Label Label::GetToolchainLabel() const {
 244   return Label(toolchain_dir_, toolchain_name_);
 245 }
 246
 247 Label Label::GetWithNoToolchain() const {
 248   return Label(dir_, name_);
 249 }
 250
 251 std::string Label::GetUserVisibleName(bool include_toolchain) const {
 252   std::string ret;
 253   ret.reserve(dir_.value().size() + name_.size() + 1);
 254
 255   if (dir_.is_null())
 256     return ret;
 257
 258   ret = DirWithNoTrailingSlash(dir_);
 259   ret.push_back(':');
 260   ret.append(name_);
 261
 262   if (include_toolchain) {
 263     ret.push_back('(');
 264     if (!toolchain_dir_.is_null() && !toolchain_name_.empty()) {
 265       ret.append(DirWithNoTrailingSlash(toolchain_dir_));
 266       ret.push_back(':');
 267       ret.append(toolchain_name_);
 268     }
 269     ret.push_back(')');
 270   }
 271   return ret;
 272 }
 273
 274 std::string Label::GetUserVisibleName(const Label& default_toolchain) const {
 275   bool include_toolchain =
 276       default_toolchain.dir() != toolchain_dir_ ||
 277       default_toolchain.name() != toolchain_name_;
 278   return GetUserVisibleName(include_toolchain);
 279 }