blob: c0a0685ca36877fca9116358f698c74ed39313bf [file] [log] [blame]
// 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;
TrimWhitespaceASCII(result, TRIM_ALL, &result);
const int kMaxSize = 50;
if (result.size() > kMaxSize) {
trimmed = true;
if (trimmed)
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";
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(),
return result;
// Sets the origin of the value and any nested values with the given node.
void RecursivelySetOrigin(Value* value, const ParseNode* 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);
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);
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.
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)
"foo bar" (result will be a string)
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.
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();