tools/gn/function_read_file.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 "base/files/file_util.h"
   6 #include "tools/gn/err.h"
   7 #include "tools/gn/filesystem_utils.h"
   8 #include "tools/gn/functions.h"
   9 #include "tools/gn/input_conversion.h"
  10 #include "tools/gn/input_file.h"
  11 #include "tools/gn/scheduler.h"
  12
  13 // TODO(brettw) consider removing this. I originally wrote it for making the
  14 // WebKit bindings but misundersood what was required, and didn't need to
  15 // use this. This seems to have a high potential for misuse.
  16
  17 namespace functions {
  18
  19 const char kReadFile[] = "read_file";
  20 const char kReadFile_HelpShort[] =
  21     "read_file: Read a file into a variable.";
  22 const char kReadFile_Help[] =
  23     "read_file: Read a file into a variable.\n"
  24     "\n"
  25     "  read_file(filename, input_conversion)\n"
  26     "\n"
  27     "  Whitespace will be trimmed from the end of the file. Throws an error\n"
  28     "  if the file can not be opened.\n"
  29     "\n"
  30     "Arguments:\n"
  31     "\n"
  32     "  filename\n"
  33     "      Filename to read, relative to the build file.\n"
  34     "\n"
  35     "  input_conversion\n"
  36     "      Controls how the file is read and parsed.\n"
  37     "      See \"gn help input_conversion\".\n"
  38     "\n"
  39     "Example\n"
  40     "  lines = read_file(\"foo.txt\", \"list lines\")\n";
  41
  42 Value RunReadFile(Scope* scope,
  43                   const FunctionCallNode* function,
  44                   const std::vector<Value>& args,
  45                   Err* err) {
  46   if (args.size() != 2) {
  47     *err = Err(function->function(), "Wrong number of arguments to read_file",
  48                "I expected two arguments.");
  49     return Value();
  50   }
  51   if (!args[0].VerifyTypeIs(Value::STRING, err))
  52     return Value();
  53
  54   // Compute the file name.
  55   const SourceDir& cur_dir = scope->GetSourceDir();
  56   SourceFile source_file = cur_dir.ResolveRelativeFile(args[0], err,
  57       scope->settings()->build_settings()->root_path_utf8());
  58   if (err->has_error())
  59     return Value();
  60   base::FilePath file_path =
  61       scope->settings()->build_settings()->GetFullPath(source_file);
  62
  63   // Ensure that everything is recomputed if the read file changes.
  64   g_scheduler->AddGenDependency(file_path);
  65
  66   // Read contents.
  67   std::string file_contents;
  68   if (!base::ReadFileToString(file_path, &file_contents)) {
  69     *err = Err(args[0], "Could not read file.",
  70                "I resolved this to \"" + FilePathToUTF8(file_path) + "\".");
  71     return Value();
  72   }
  73
  74   return ConvertInputToValue(scope->settings(), file_contents, function,
  75                              args[1], err);
  76 }
  77
  78 }  // namespace functions