243 lines
8.3 KiB
C++
243 lines
8.3 KiB
C++
//
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// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// -----------------------------------------------------------------------------
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// File: ascii.h
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// -----------------------------------------------------------------------------
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//
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// This package contains functions operating on characters and strings
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// restricted to standard ASCII. These include character classification
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// functions analogous to those found in the ANSI C Standard Library <ctype.h>
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// header file.
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//
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// C++ implementations provide <ctype.h> functionality based on their
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// C environment locale. In general, reliance on such a locale is not ideal, as
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// the locale standard is problematic (and may not return invariant information
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// for the same character set, for example). These `ascii_*()` functions are
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// hard-wired for standard ASCII, much faster, and guaranteed to behave
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// consistently. They will never be overloaded, nor will their function
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// signature change.
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//
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// `ascii_isalnum()`, `ascii_isalpha()`, `ascii_isascii()`, `ascii_isblank()`,
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// `ascii_iscntrl()`, `ascii_isdigit()`, `ascii_isgraph()`, `ascii_islower()`,
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// `ascii_isprint()`, `ascii_ispunct()`, `ascii_isspace()`, `ascii_isupper()`,
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// `ascii_isxdigit()`
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// Analogous to the <ctype.h> functions with similar names, these
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// functions take an unsigned char and return a bool, based on whether the
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// character matches the condition specified.
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//
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// If the input character has a numerical value greater than 127, these
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// functions return `false`.
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//
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// `ascii_tolower()`, `ascii_toupper()`
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// Analogous to the <ctype.h> functions with similar names, these functions
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// take an unsigned char and return a char.
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//
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// If the input character is not an ASCII {lower,upper}-case letter (including
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// numerical values greater than 127) then the functions return the same value
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// as the input character.
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#ifndef ABSL_STRINGS_ASCII_H_
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#define ABSL_STRINGS_ASCII_H_
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#include <algorithm>
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#include <string>
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#include "absl/base/attributes.h"
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#include "absl/base/config.h"
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#include "absl/strings/string_view.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace ascii_internal {
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// Declaration for an array of bitfields holding character information.
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ABSL_DLL extern const unsigned char kPropertyBits[256];
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// Declaration for the array of characters to upper-case characters.
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ABSL_DLL extern const char kToUpper[256];
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// Declaration for the array of characters to lower-case characters.
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ABSL_DLL extern const char kToLower[256];
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} // namespace ascii_internal
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// ascii_isalpha()
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//
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// Determines whether the given character is an alphabetic character.
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inline bool ascii_isalpha(unsigned char c) {
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return (ascii_internal::kPropertyBits[c] & 0x01) != 0;
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}
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// ascii_isalnum()
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//
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// Determines whether the given character is an alphanumeric character.
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inline bool ascii_isalnum(unsigned char c) {
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return (ascii_internal::kPropertyBits[c] & 0x04) != 0;
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}
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// ascii_isspace()
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//
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// Determines whether the given character is a whitespace character (space,
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// tab, vertical tab, formfeed, linefeed, or carriage return).
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inline bool ascii_isspace(unsigned char c) {
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return (ascii_internal::kPropertyBits[c] & 0x08) != 0;
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}
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// ascii_ispunct()
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//
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// Determines whether the given character is a punctuation character.
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inline bool ascii_ispunct(unsigned char c) {
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return (ascii_internal::kPropertyBits[c] & 0x10) != 0;
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}
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// ascii_isblank()
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//
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// Determines whether the given character is a blank character (tab or space).
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inline bool ascii_isblank(unsigned char c) {
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return (ascii_internal::kPropertyBits[c] & 0x20) != 0;
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}
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// ascii_iscntrl()
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//
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// Determines whether the given character is a control character.
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inline bool ascii_iscntrl(unsigned char c) {
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return (ascii_internal::kPropertyBits[c] & 0x40) != 0;
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}
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// ascii_isxdigit()
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//
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// Determines whether the given character can be represented as a hexadecimal
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// digit character (i.e. {0-9} or {A-F}).
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inline bool ascii_isxdigit(unsigned char c) {
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return (ascii_internal::kPropertyBits[c] & 0x80) != 0;
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}
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// ascii_isdigit()
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//
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// Determines whether the given character can be represented as a decimal
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// digit character (i.e. {0-9}).
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inline bool ascii_isdigit(unsigned char c) { return c >= '0' && c <= '9'; }
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// ascii_isprint()
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//
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// Determines whether the given character is printable, including whitespace.
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inline bool ascii_isprint(unsigned char c) { return c >= 32 && c < 127; }
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// ascii_isgraph()
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//
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// Determines whether the given character has a graphical representation.
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inline bool ascii_isgraph(unsigned char c) { return c > 32 && c < 127; }
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// ascii_isupper()
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//
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// Determines whether the given character is uppercase.
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inline bool ascii_isupper(unsigned char c) { return c >= 'A' && c <= 'Z'; }
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// ascii_islower()
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//
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// Determines whether the given character is lowercase.
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inline bool ascii_islower(unsigned char c) { return c >= 'a' && c <= 'z'; }
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// ascii_isascii()
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//
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// Determines whether the given character is ASCII.
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inline bool ascii_isascii(unsigned char c) { return c < 128; }
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// ascii_tolower()
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//
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// Returns an ASCII character, converting to lowercase if uppercase is
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// passed. Note that character values > 127 are simply returned.
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inline char ascii_tolower(unsigned char c) {
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return ascii_internal::kToLower[c];
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}
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// Converts the characters in `s` to lowercase, changing the contents of `s`.
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void AsciiStrToLower(std::string* s);
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// Creates a lowercase string from a given absl::string_view.
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ABSL_MUST_USE_RESULT inline std::string AsciiStrToLower(absl::string_view s) {
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std::string result(s);
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absl::AsciiStrToLower(&result);
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return result;
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}
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// ascii_toupper()
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//
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// Returns the ASCII character, converting to upper-case if lower-case is
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// passed. Note that characters values > 127 are simply returned.
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inline char ascii_toupper(unsigned char c) {
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return ascii_internal::kToUpper[c];
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}
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// Converts the characters in `s` to uppercase, changing the contents of `s`.
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void AsciiStrToUpper(std::string* s);
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// Creates an uppercase string from a given absl::string_view.
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ABSL_MUST_USE_RESULT inline std::string AsciiStrToUpper(absl::string_view s) {
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std::string result(s);
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absl::AsciiStrToUpper(&result);
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return result;
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}
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// Returns absl::string_view with whitespace stripped from the beginning of the
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// given string_view.
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ABSL_MUST_USE_RESULT inline absl::string_view StripLeadingAsciiWhitespace(
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absl::string_view str) {
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auto it = std::find_if_not(str.begin(), str.end(), absl::ascii_isspace);
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return str.substr(it - str.begin());
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}
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// Strips in place whitespace from the beginning of the given string.
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inline void StripLeadingAsciiWhitespace(std::string* str) {
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auto it = std::find_if_not(str->begin(), str->end(), absl::ascii_isspace);
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str->erase(str->begin(), it);
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}
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// Returns absl::string_view with whitespace stripped from the end of the given
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// string_view.
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ABSL_MUST_USE_RESULT inline absl::string_view StripTrailingAsciiWhitespace(
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absl::string_view str) {
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auto it = std::find_if_not(str.rbegin(), str.rend(), absl::ascii_isspace);
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return str.substr(0, str.rend() - it);
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}
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// Strips in place whitespace from the end of the given string
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inline void StripTrailingAsciiWhitespace(std::string* str) {
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auto it = std::find_if_not(str->rbegin(), str->rend(), absl::ascii_isspace);
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str->erase(str->rend() - it);
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}
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// Returns absl::string_view with whitespace stripped from both ends of the
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// given string_view.
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ABSL_MUST_USE_RESULT inline absl::string_view StripAsciiWhitespace(
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absl::string_view str) {
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return StripTrailingAsciiWhitespace(StripLeadingAsciiWhitespace(str));
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}
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// Strips in place whitespace from both ends of the given string
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inline void StripAsciiWhitespace(std::string* str) {
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StripTrailingAsciiWhitespace(str);
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StripLeadingAsciiWhitespace(str);
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}
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// Removes leading, trailing, and consecutive internal whitespace.
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void RemoveExtraAsciiWhitespace(std::string*);
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ABSL_NAMESPACE_END
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} // namespace absl
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#endif // ABSL_STRINGS_ASCII_H_
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