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