//

// Copyright 2017 The Abseil Authors.

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//      https://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

//

// -----------------------------------------------------------------------------

// File: strip.h

// -----------------------------------------------------------------------------

//

// This file contains various functions for stripping substrings from a string.

#ifndef ABSL_STRINGS_STRIP_H_

#define ABSL_STRINGS_STRIP_H_

#include <cstddef>

#include <string>

#include "absl/base/macros.h"

#include "absl/strings/ascii.h"

#include "absl/strings/match.h"

#include "absl/strings/string_view.h"

namespace absl {

ABSL_NAMESPACE_BEGIN

// ConsumePrefix()

//

// Strips the `expected` prefix, if found, from the start of `str`.

// If the operation succeeded, `true` is returned.  If not, `false`

// is returned and `str` is not modified.

//

// Example:

//

//   absl::string_view input("abc");

//   EXPECT_TRUE(absl::ConsumePrefix(&input, "a"));

//   EXPECT_EQ(input, "bc");

inline bool ConsumePrefix(absl::string_view* str, absl::string_view expected) {

  if (!absl::StartsWith(*str, expected)) return false;

  str->remove_prefix(expected.size());

  return true;

}

// ConsumeSuffix()

//

// Strips the `expected` suffix, if found, from the end of `str`.

// If the operation succeeded, `true` is returned.  If not, `false`

// is returned and `str` is not modified.

//

// Example:

//

//   absl::string_view input("abcdef");

//   EXPECT_TRUE(absl::ConsumeSuffix(&input, "def"));

//   EXPECT_EQ(input, "abc");

inline bool ConsumeSuffix(absl::string_view* str, absl::string_view expected) {

  if (!absl::EndsWith(*str, expected)) return false;

  str->remove_suffix(expected.size());

  return true;

}

// StripPrefix()

//

// Returns a view into the input string `str` with the given `prefix` removed,

// but leaving the original string intact. If the prefix does not match at the

// start of the string, returns the original string instead.

ABSL_MUST_USE_RESULT inline absl::string_view StripPrefix(

    absl::string_view str, absl::string_view prefix) {

  if (absl::StartsWith(str, prefix)) str.remove_prefix(prefix.size());

  return str;

}

// StripSuffix()

//

// Returns a view into the input string `str` with the given `suffix` removed,

// but leaving the original string intact. If the suffix does not match at the

// end of the string, returns the original string instead.

ABSL_MUST_USE_RESULT inline absl::string_view StripSuffix(

    absl::string_view str, absl::string_view suffix) {

  if (absl::EndsWith(str, suffix)) str.remove_suffix(suffix.size());

  return str;

}

ABSL_NAMESPACE_END

}  // namespace absl

#endif  // ABSL_STRINGS_STRIP_H_