Revert 214254 "Add initial prototype for the GN meta-buildsystem."

trunk/src/tools/gn/input_conversion.cc

-// 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 "input_conversion.h"
-
-#include "base/strings/string_split.h"
-#include "base/strings/string_util.h"
-#include "tools/gn/build_settings.h"
-#include "tools/gn/err.h"
-#include "tools/gn/input_file.h"
-#include "tools/gn/label.h"
-#include "tools/gn/parse_tree.h"
-#include "tools/gn/parser.h"
-#include "tools/gn/scope.h"
-#include "tools/gn/settings.h"
-#include "tools/gn/tokenizer.h"
-#include "tools/gn/value.h"
-
-namespace {
-
-// Returns the "first bit" of some script output for writing to error messages.
-std::string GetExampleOfBadInput(const std::string& input) {
-  std::string result(input);
-
-  // Maybe the result starts with a blank line or something, which we don't
-  // want.
-  TrimWhitespaceASCII(result, TRIM_ALL, &result);
-
-  // Now take the first line, or the first set of chars, whichever is shorter.
-  bool trimmed = false;
-  size_t newline_offset = result.find('\n');
-  if (newline_offset != std::string::npos) {
-    trimmed = true;
-    result.resize(newline_offset);
-  }
-  TrimWhitespaceASCII(result, TRIM_ALL, &result);
-
-  const int kMaxSize = 50;
-  if (result.size() > kMaxSize) {
-    trimmed = true;
-    result.resize(kMaxSize);
-  }
-
-  if (trimmed)
-    result.append("...");
-  return result;
-}
-
-// When parsing the result as a value, we may get various types of errors.
-// This creates an error message for this case with an optional nested error
-// message to reference. If there is no nested err, pass Err().
-//
-// This code also takes care to rewrite the original error which will reference
-// the temporary InputFile which won't exist when the error is propogated
-// out to a higher level.
-Err MakeParseErr(const std::string& input,
-                 const ParseNode* origin,
-                 const Err& nested) {
-  std::string help_text =
-      "When parsing a result as a \"value\" it should look like a list:\n"
-      "  [ \"a\", \"b\", 5 ]\n"
-      "or a single literal:\n"
-      "  \"my result\"\n"
-      "but instead I got this, which I find very confusing:\n";
-  help_text.append(input);
-  if (nested.has_error())
-    help_text.append("\nThe exact error was:");
-
-  Err result(origin, "Script result wasn't a valid value.", help_text);
-  if (nested.has_error()) {
-    result.AppendSubErr(Err(LocationRange(), nested.message(),
-                            nested.help_text()));
-  }
-  return result;
-}
-
-// Sets the origin of the value and any nested values with the given node.
-void RecursivelySetOrigin(Value* value, const ParseNode* origin) {
-  value->set_origin(origin);
-  if (value->type() == Value::LIST) {
-    std::vector<Value>& list_value = value->list_value();
-    for (size_t i = 0; i < list_value.size(); i++)
-      RecursivelySetOrigin(&list_value[i], origin);
-  }
-}
-
-Value ParseString(const std::string& input,
-                  const ParseNode* origin,
-                  Err* err) {
-  SourceFile empty_source_for_most_vexing_parse;
-  InputFile input_file(empty_source_for_most_vexing_parse);
-  input_file.SetContents(input);
-
-  std::vector<Token> tokens = Tokenizer::Tokenize(&input_file, err);
-  if (err->has_error()) {
-    *err = MakeParseErr(input, origin, *err);
-    return Value();
-  }
-
-  scoped_ptr<ParseNode> expression = Parser::ParseExpression(tokens, err);
-  if (err->has_error()) {
-    *err = MakeParseErr(input, origin, *err);
-    return Value();
-  }
-
-  // It's valid for the result to be a null pointer, this just means that the
-  // script returned nothing.
-  if (!expression)
-    return Value();
-
-  // The result should either be a list or a literal, anything else is
-  // invalid.
-  if (!expression->AsList() && !expression->AsLiteral()) {
-    *err = MakeParseErr(input, origin, Err());
-    return Value();
-  }
-
-  BuildSettings build_settings;
-  Label empty_label;
-  Toolchain toolchain(empty_label);
-  Settings settings(&build_settings, &toolchain, std::string());
-  Scope scope(&settings);
-
-  Err nested_err;
-  Value result = expression->Execute(&scope, &nested_err);
-  if (nested_err.has_error()) {
-    *err = MakeParseErr(input, origin, nested_err);
-    return Value();
-  }
-
-  // The returned value will have references to the temporary parse nodes we
-  // made on the stack. If the values are used in an error message in the
-  // future, this will crash. Reset the origin of all values to be our
-  // containing origin.
-  RecursivelySetOrigin(&result, origin);
-  return result;
-}
-
-Value ParseList(const std::string& input,
-                const ParseNode* origin,
-                Err* err) {
-  Value ret(origin, Value::LIST);
-  std::vector<std::string> as_lines;
-  base::SplitString(input, '\n', &as_lines);
-
-  // Trim empty lines from the end.
-  // Do we want to make this configurable?
-  while (!as_lines.empty() && as_lines[as_lines.size() - 1].empty())
-    as_lines.resize(as_lines.size() - 1);
-
-  ret.list_value().reserve(as_lines.size());
-  for (size_t i = 0; i < as_lines.size(); i++)
-    ret.list_value().push_back(Value(origin, as_lines[i]));
-  return ret;
-}
-
-}  // namespace
-
-/*
-input_conversion: Specifies how to transform input to a variable.
-
-  input_conversion is an argument to read_file and exec_script that specifies
-  how the result of the read operation should be converted into a variable.
-
-  "list lines":
-      Return the file contents as a list, with a string for each line. The
-      newlines will not be present in the result. Empty newlines will be
-      trimmed from the trailing end of the returned list.
-
-  "value":
-      Parse the input as if it was a literal rvalue in a buildfile.
-      Examples of typical program output using this mode:
-        [ "foo", "bar" ]     (result will be a list)
-      or
-        "foo bar"            (result will be a string)
-      or
-        5                    (result will be an integer)
-
-      Note that if the input is empty, the result will be a null value which
-      will produce an error if assigned to a variable.
-
-  "string":
-      Return the file contents into a single string.
-*/
-
-Value ConvertInputToValue(const std::string& input,
-                          const ParseNode* origin,
-                          const Value& input_conversion_value,
-                          Err* err) {
-  if (!input_conversion_value.VerifyTypeIs(Value::STRING, err))
-    return Value();
-  const std::string& input_conversion = input_conversion_value.string_value();
-
-  if (input_conversion == "value")
-    return ParseString(input, origin, err);
-  if (input_conversion == "string")
-    return Value(origin, input);
-  if (input_conversion == "list lines")
-    return ParseList(input, origin, err);
-
-  *err = Err(input_conversion_value, "Not a valid read file mode.",
-             "Have you considered a career in retail?");
-  return Value();
-}