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// 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/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 {
// 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.
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;
Settings settings(&build_settings, 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.
result.RecursivelySetOrigin(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 one empty line from the end since the last line might end in a
// newline. If the user wants more trimming, they'll specify "trim" in the
// input conversion options.
if (!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;
}
// Backend for ConvertInputToValue, this takes the extracted string for the
// input conversion so we can recursively call ourselves to handle the optional
// "trim" prefix. This original value is also kept for the purposes of throwing
// errors.
Value DoConvertInputToValue(const std::string& input,
const ParseNode* origin,
const Value& original_input_conversion,
const std::string& input_conversion,
Err* err) {
if (input_conversion.empty())
return Value(); // Empty string means discard the result.
const char kTrimPrefix[] = "trim ";
if (StartsWithASCII(input_conversion, kTrimPrefix, true)) {
std::string trimmed;
base::TrimWhitespaceASCII(input, base::TRIM_ALL, &trimmed);
// Remove "trim" prefix from the input conversion and re-run.
return DoConvertInputToValue(
trimmed, origin, original_input_conversion,
input_conversion.substr(arraysize(kTrimPrefix) - 1), err);
}
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(original_input_conversion, "Not a valid input_conversion.",
"Have you considered a career in retail?");
return Value();
}
} // namespace
extern const char kInputConversion_Help[] =
"input_conversion: Specifies how to transform input to a variable.\n"
"\n"
" input_conversion is an argument to read_file and exec_script that\n"
" specifies how the result of the read operation should be converted\n"
" into a variable.\n"
"\n"
" \"\" (the default)\n"
" Discard the result and return None.\n"
"\n"
" \"list lines\"\n"
" Return the file contents as a list, with a string for each line.\n"
" The newlines will not be present in the result. The last line may\n"
" or may not end in a newline.\n"
"\n"
" After splitting, each individual line will be trimmed of\n"
" whitespace on both ends.\n"
"\n"
" \"value\"\n"
" Parse the input as if it was a literal rvalue in a buildfile.\n"
" Examples of typical program output using this mode:\n"
" [ \"foo\", \"bar\" ] (result will be a list)\n"
" or\n"
" \"foo bar\" (result will be a string)\n"
" or\n"
" 5 (result will be an integer)\n"
"\n"
" Note that if the input is empty, the result will be a null value\n"
" which will produce an error if assigned to a variable.\n"
"\n"
" \"string\"\n"
" Return the file contents into a single string.\n"
"\n"
" \"trim ...\"\n"
" Prefixing any of the other transformations with the word \"trim\"\n"
" will result in whitespace being trimmed from the beginning and end\n"
" of the result before processing.\n"
"\n"
" Examples: \"trim string\" or \"trim list lines\"\n"
"\n"
" Note that \"trim value\" is useless because the value parser skips\n"
" whitespace anyway.\n";
Value ConvertInputToValue(const std::string& input,
const ParseNode* origin,
const Value& input_conversion_value,
Err* err) {
if (input_conversion_value.type() == Value::NONE)
return Value(); // Allow null inputs to mean discard the result.
if (!input_conversion_value.VerifyTypeIs(Value::STRING, err))
return Value();
return DoConvertInputToValue(input, origin, input_conversion_value,
input_conversion_value.string_value(), err);
}
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