Add initial prototype for the GN meta-buildsystem.

tools/gn/filesystem_utils.cc

Index: tools/gn/filesystem_utils.cc
diff --git a/tools/gn/filesystem_utils.cc b/tools/gn/filesystem_utils.cc
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index 0000000000000000000000000000000000000000..625a358a791e6247b7f4f516edce83dddfb08ff5
--- /dev/null
+++ b/tools/gn/filesystem_utils.cc
@@ -0,0 +1,350 @@
+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "tools/gn/filesystem_utils.h"
+
+#include "base/logging.h"
+#include "base/strings/utf_string_conversions.h"
+#include "build/build_config.h"
+#include "tools/gn/location.h"
+#include "tools/gn/source_dir.h"
+
+namespace {
+
+enum DotDisposition {
+  // The given dot is just part of a filename and is not special.
+  NOT_A_DIRECTORY,
+
+  // The given dot is the current directory.
+  DIRECTORY_CUR,
+
+  // The given dot is the first of a double dot that should take us up one.
+  DIRECTORY_UP
+};
+
+// When we find a dot, this function is called with the character following
+// that dot to see what it is. The return value indicates what type this dot is
+// (see above). This code handles the case where the dot is at the end of the
+// input.
+//
+// |*consumed_len| will contain the number of characters in the input that
+// express what we found.
+DotDisposition ClassifyAfterDot(const std::string& path,
+                                size_t after_dot,
+                                size_t* consumed_len) {
+  if (after_dot == path.size()) {
+    // Single dot at the end.
+    *consumed_len = 1;
+    return DIRECTORY_CUR;
+  }
+  if (path[after_dot] == '/') {
+    // Single dot followed by a slash.
+    *consumed_len = 2;  // Consume the slash
+    return DIRECTORY_CUR;
+  }
+
+  if (path[after_dot] == '.') {
+    // Two dots.
+    if (after_dot + 1 == path.size()) {
+      // Double dot at the end.
+      *consumed_len = 2;
+      return DIRECTORY_UP;
+    }
+    if (path[after_dot + 1] == '/') {
+      // Double dot folowed by a slash.
+      *consumed_len = 3;
+      return DIRECTORY_UP;
+    }
+  }
+
+  // The dots are followed by something else, not a directory.
+  *consumed_len = 1;
+  return NOT_A_DIRECTORY;
+}
+
+}  // namesapce
+
+SourceFileType GetSourceFileType(const SourceFile& file,
+                                 Settings::TargetOS os) {
+  base::StringPiece extension = FindExtension(&file.value());
+  if (extension == "cc" || extension == "cpp" || extension == "cxx")
+    return SOURCE_CC;
+  if (extension == "h")
+    return SOURCE_H;
+  if (extension == "c")
+    return SOURCE_C;
+
+  switch (os) {
+    case Settings::MAC:
+      if (extension == "m")
+        return SOURCE_M;
+      if (extension == "mm")
+        return SOURCE_MM;
+      break;
+
+    case Settings::WIN:
+      if (extension == "rc")
+        return SOURCE_RC;
+      break;
+
+    default:
+      break;
+  }
+
+  // TODO(brettw) asm files.
+  // TODO(brettw) weird thing with .S on non-Windows platforms.
+  return SOURCE_UNKNOWN;
+}
+
+const char* GetExtensionForOutputType(Target::OutputType type,
+                                      Settings::TargetOS os) {
+  switch (os) {
+    case Settings::WIN:
+      switch (type) {
+        case Target::NONE:
+          NOTREACHED();
+          return "";
+        case Target::EXECUTABLE:
+          return "exe";
+        case Target::SHARED_LIBRARY:
+          return "dll.lib";  // Extension of import library.
+        case Target::STATIC_LIBRARY:
+          return "lib";
+        case Target::LOADABLE_MODULE:
+          return "dll";  // TODO(brettw) what's this?
+        default:
+          NOTREACHED();
+      }
+      break;
+
+    default:
+      NOTREACHED();
+  }
+  return "";
+}
+
+std::string FilePathToUTF8(const base::FilePath& path) {
+#if defined(OS_WIN)
+  return WideToUTF8(path.value());
+#else
+  return path.value();
+#endif
+}
+
+base::FilePath UTF8ToFilePath(const base::StringPiece& sp) {
+#if defined(OS_WIN)
+  return base::FilePath(UTF8ToWide(sp));
+#else
+  return base::FilePath(sp.as_string());
+#endif
+}
+
+size_t FindExtensionOffset(const std::string& path) {
+  for (int i = static_cast<int>(path.size()); i >= 0; i--) {
+    if (path[i] == '/')
+      break;
+    if (path[i] == '.')
+      return i + 1;
+  }
+  return std::string::npos;
+}
+
+base::StringPiece FindExtension(const std::string* path) {
+  size_t extension_offset = FindExtensionOffset(*path);
+  if (extension_offset == std::string::npos)
+    return base::StringPiece();
+  return base::StringPiece(&path->data()[extension_offset],
+                           path->size() - extension_offset);
+}
+
+size_t FindFilenameOffset(const std::string& path) {
+  for (int i = static_cast<int>(path.size()) - 1; i >= 0; i--) {
+    if (path[i] == '/')
+      return i + 1;
+  }
+  return 0;  // No filename found means everything was the filename.
+}
+
+base::StringPiece FindFilename(const std::string* path) {
+  size_t filename_offset = FindFilenameOffset(*path);
+  if (filename_offset == 0)
+    return base::StringPiece(*path);  // Everything is the file name.
+  return base::StringPiece(&(*path).data()[filename_offset],
+                           path->size() - filename_offset);
+}
+
+base::StringPiece FindFilenameNoExtension(const std::string* path) {
+  if (path->empty())
+    return base::StringPiece();
+  size_t filename_offset = FindFilenameOffset(*path);
+  size_t extension_offset = FindExtensionOffset(*path);
+
+  size_t name_len;
+  if (extension_offset == std::string::npos)
+    name_len = path->size() - filename_offset;
+  else
+    name_len = extension_offset - filename_offset - 1;
+
+  return base::StringPiece(&(*path).data()[filename_offset], name_len);
+}
+
+void RemoveFilename(std::string* path) {
+  path->resize(FindFilenameOffset(*path));
+}
+
+bool EndsWithSlash(const std::string& s) {
+  return !s.empty() && s[s.size() - 1] == '/';
+}
+
+base::StringPiece FindDir(const std::string* path) {
+  size_t filename_offset = FindFilenameOffset(*path);
+  if (filename_offset == 0u)
+    return base::StringPiece();
+  return base::StringPiece(path->data(), filename_offset);
+}
+
+bool EnsureStringIsInOutputDir(const SourceDir& dir,
+                               const std::string& str,
+                               const Value& originating,
+                               Err* err) {
+  // The last char of the dir will be a slash. We don't care if the input ends
+  // in a slash or not, so just compare up until there.
+  //
+  // This check will be wrong for all proper prefixes "e.g. "/output" will
+  // match "/out" but we don't really care since this is just a sanity check.
+  const std::string& dir_str = dir.value();
+  if (str.compare(0, dir_str.length() - 1, dir_str, 0, dir_str.length() - 1)
+      != 0) {
+    *err = Err(originating, "File not inside output directory.",
+        "The given file should be in the output directory. Normally you would "
+        "specify\n\"$target_output_dir/foo\" or "
+        "\"$target_gen_dir/foo\". I interpreted this as\n\""
+        + str + "\".");
+    return false;
+  }
+  return true;
+}
+
+std::string InvertDir(const SourceDir& path) {
+  const std::string value = path.value();
+  if (value.empty())
+    return std::string();
+
+  DCHECK(value[0] == '/');
+  size_t begin_index = 1;
+
+  // If the input begins with two slashes, skip over both (this is a
+  // source-relative dir).
+  if (value.size() > 1 && value[1] == '/')
+    begin_index = 2;
+
+  std::string ret;
+  for (size_t i = begin_index; i < value.size(); i++) {
+    if (value[i] == '/')
+      ret.append("../");
+  }
+  return ret;
+}
+
+void NormalizePath(std::string* path) {
+  char* pathbuf = path->empty() ? NULL : &(*path)[0];
+
+  // top_index is the first character we can modify in the path. Anything
+  // before this indicates where the path is relative to.
+  size_t top_index = 0;
+  bool is_relative = true;
+  if (!path->empty() && pathbuf[0] == '/') {
+    is_relative = false;
+
+    if (path->size() > 1 && pathbuf[1] == '/') {
+      // Two leading slashes, this is a path into the source dir.
+      top_index = 2;
+    } else {
+      // One leading slash, this is a system-absolute path.
+      top_index = 1;
+    }
+  }
+
+  size_t dest_i = top_index;
+  for (size_t src_i = top_index; src_i < path->size(); /* nothing */) {
+    if (pathbuf[src_i] == '.') {
+      if (src_i == 0 || pathbuf[src_i - 1] == '/') {
+        // Slash followed by a dot, see if it's something special.
+        size_t consumed_len;
+        switch (ClassifyAfterDot(*path, src_i + 1, &consumed_len)) {
+          case NOT_A_DIRECTORY:
+            // Copy the dot to the output, it means nothing special.
+            pathbuf[dest_i++] = pathbuf[src_i++];
+            break;
+          case DIRECTORY_CUR:
+            // Current directory, just skip the input.
+            src_i += consumed_len;
+            break;
+          case DIRECTORY_UP:
+            // Back up over previous directory component. If we're already
+            // at the top, preserve the "..".
+            if (dest_i > top_index) {
+              // The previous char was a slash, remove it.
+              dest_i--;
+            }
+
+            if (dest_i == top_index) {
+              if (is_relative) {
+                // We're already at the beginning of a relative input, copy the
+                // ".." and continue. We need the trailing slash if there was
+                // one before (otherwise we're at the end of the input).
+                pathbuf[dest_i++] = '.';
+                pathbuf[dest_i++] = '.';
+                if (consumed_len == 3)
+                  pathbuf[dest_i++] = '/';
+
+                // This also makes a new "root" that we can't delete by going
+                // up more levels.  Otherwise "../.." would collapse to
+                // nothing.
+                top_index = dest_i;
+              }
+              // Otherwise we're at the beginning of an absolute path. Don't
+              // allow ".." to go up another level and just eat it.
+            } else {
+              // Just find the previous slash or the beginning of input.
+              while (dest_i > 0 && pathbuf[dest_i - 1] != '/')
+                dest_i--;
+            }
+            src_i += consumed_len;
+        }
+      } else {
+        // Dot not preceeded by a slash, copy it literally.
+        pathbuf[dest_i++] = pathbuf[src_i++];
+      }
+    } else if (pathbuf[src_i] == '/') {
+      if (src_i > 0 && pathbuf[src_i - 1] == '/') {
+        // Two slashes in a row, skip over it.
+        src_i++;
+      } else {
+        // Just one slash, copy it.
+        pathbuf[dest_i++] = pathbuf[src_i++];
+      }
+    } else {
+      // Input nothing special, just copy it.
+      pathbuf[dest_i++] = pathbuf[src_i++];
+    }
+  }
+  path->resize(dest_i);
+}
+
+void ConvertPathToSystem(std::string* path) {
+#if defined(OS_WIN)
+  for (size_t i = 0; i < path->size(); i++) {
+    if ((*path)[i] == '/')
+      (*path)[i] = '\\';
+  }
+#endif
+}
+
+std::string PathToSystem(const std::string& path) {
+  std::string ret(path);
+  ConvertPathToSystem(&ret);
+  return ret;
+}
+