Enhance GN diagnostic tools

tools/gn/label_pattern.h

Index: tools/gn/label_pattern.h
diff --git a/tools/gn/label_pattern.h b/tools/gn/label_pattern.h
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+// Copyright 2014 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.
+
+#ifndef TOOLS_GN_LABEL_PATTERN_H_
+#define TOOLS_GN_LABEL_PATTERN_H_
+
+#include "base/strings/string_piece.h"
+#include "tools/gn/label.h"
+#include "tools/gn/source_dir.h"
+
+class Err;
+class Value;
+
+extern const char kLabelPattern_Help[];
+
+// A label pattern is a simple pattern that matches labels. It is used for
+// specifying visibility and other times when multiple targets need to be
+// referenced.
+class LabelPattern {
+ public:
+  enum Type {
+    MATCH = 1,  // Exact match for a given target.
+    DIRECTORY,  // Only targets in the file in the given directory.
+    RECURSIVE_DIRECTORY  // The given directory and any subdir.
+                         // (also indicates "public" when dir is empty).
+  };
+
+  LabelPattern();
+  LabelPattern(Type type,
+               const SourceDir& dir,
+               const base::StringPiece& name,
+               const Label& toolchain_label);
+  ~LabelPattern();
+
+  // Converts the given input string to a pattern. This does special stuff
+  // to treat the pattern as a label. Sets the error on failure.
+  static LabelPattern GetPattern(const SourceDir& current_dir,
+                                 const Value& value,
+                                 Err* err);
+
+  // Returns true if this pattern matches the given label.
+  bool Matches(const Label& label) const;
+
+  // Returns a string representation of this pattern.
+  std::string Describe() const;
+
+  Type type() const { return type_; }
+
+  const SourceDir& dir() const { return dir_; }
+  const std::string& name() const { return name_; }
+
+  const Label& toolchain() const { return toolchain_; }
+  void set_toolchain(const Label& tc) { toolchain_ = tc; }
+
+ private:
+  // If nonempty, specifies the toolchain to use. If empty, this will match
+  // all toolchains. This is independent of the match type.
+  Label toolchain_;
+
+  Type type_;
+
+  // Used when type_ == PRIVATE and PRIVATE_RECURSIVE. This specifies the
+  // directory that to which the pattern is private to.
+  SourceDir dir_;
+
+  // Empty name means match everything. Otherwise the name must match
+  // exactly.
+  std::string name_;
+};
+
+#endif  // TOOLS_GN_LABEL_PATTERN_H_