GN: Add logging for the location of an invocation.

tools/gn/location.cc

Index: tools/gn/location.cc
diff --git a/tools/gn/location.cc b/tools/gn/location.cc
new file mode 100644
index 0000000000000000000000000000000000000000..61f22b5e079d2c273b189192f09eb361e6acf7ea
--- /dev/null
+++ b/tools/gn/location.cc
@@ -0,0 +1,73 @@
+// 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/location.h"
+
+#include "base/logging.h"
+#include "base/strings/string_number_conversions.h"
+#include "tools/gn/input_file.h"
+
+Location::Location()
+    : file_(NULL),
+      line_number_(-1),
+      char_offset_(-1) {
+}
+
+Location::Location(const InputFile* file, int line_number, int char_offset)
+    : file_(file),
+      line_number_(line_number),
+      char_offset_(char_offset) {
+}
+
+bool Location::operator==(const Location& other) const {
+  return other.file_ == file_ &&
+         other.line_number_ == line_number_ &&
+         other.char_offset_ == char_offset_;
+}
+
+bool Location::operator!=(const Location& other) const {
+  return !operator==(other);
+}
+
+bool Location::operator<(const Location& other) const {
+  DCHECK(file_ == other.file_);
+  if (line_number_ != other.line_number_)
+    return line_number_ < other.line_number_;
+  return char_offset_ < other.char_offset_;
+}
+
+std::string Location::Describe(bool include_char_offset) const {
+  if (!file_)
+    return std::string();
+
+  std::string ret;
+  if (file_->friendly_name().empty())
+    ret = file_->name().value();
+  else
+    ret = file_->friendly_name();
+
+  ret += ":";
+  ret += base::IntToString(line_number_);
+  if (include_char_offset) {
+    ret += ":";
+    ret += base::IntToString(char_offset_);
+  }
+  return ret;
+}
+
+LocationRange::LocationRange() {
+}
+
+LocationRange::LocationRange(const Location& begin, const Location& end)
+    : begin_(begin),
+      end_(end) {
+  DCHECK(begin_.file() == end_.file());
+}
+
+LocationRange LocationRange::Union(const LocationRange& other) const {
+  DCHECK(begin_.file() == other.begin_.file());
+  return LocationRange(
+      begin_ < other.begin_ ? begin_ : other.begin_,
+      end_ < other.end_ ? other.end_ : end_);
+}