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- //
- // 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: ascii.h
- // -----------------------------------------------------------------------------
- //
- // This package contains functions operating on characters and strings
- // restricted to standard ASCII. These include character classification
- // functions analogous to those found in the ANSI C Standard Library <ctype.h>
- // header file.
- //
- // C++ implementations provide <ctype.h> functionality based on their
- // C environment locale. In general, reliance on such a locale is not ideal, as
- // the locale standard is problematic (and may not return invariant information
- // for the same character set, for example). These `ascii_*()` functions are
- // hard-wired for standard ASCII, much faster, and guaranteed to behave
- // consistently. They will never be overloaded, nor will their function
- // signature change.
- //
- // `ascii_isalnum()`, `ascii_isalpha()`, `ascii_isascii()`, `ascii_isblank()`,
- // `ascii_iscntrl()`, `ascii_isdigit()`, `ascii_isgraph()`, `ascii_islower()`,
- // `ascii_isprint()`, `ascii_ispunct()`, `ascii_isspace()`, `ascii_isupper()`,
- // `ascii_isxdigit()`
- // Analogous to the <ctype.h> functions with similar names, these
- // functions take an unsigned char and return a bool, based on whether the
- // character matches the condition specified.
- //
- // If the input character has a numerical value greater than 127, these
- // functions return `false`.
- //
- // `ascii_tolower()`, `ascii_toupper()`
- // Analogous to the <ctype.h> functions with similar names, these functions
- // take an unsigned char and return a char.
- //
- // If the input character is not an ASCII {lower,upper}-case letter (including
- // numerical values greater than 127) then the functions return the same value
- // as the input character.
- #ifndef ABSL_STRINGS_ASCII_H_
- #define ABSL_STRINGS_ASCII_H_
- #include <algorithm>
- #include <string>
- #include "absl/base/attributes.h"
- #include "absl/base/config.h"
- #include "absl/strings/string_view.h"
- namespace absl {
- ABSL_NAMESPACE_BEGIN
- namespace ascii_internal {
- // Declaration for an array of bitfields holding character information.
- ABSL_DLL extern const unsigned char kPropertyBits[256];
- // Declaration for the array of characters to upper-case characters.
- ABSL_DLL extern const char kToUpper[256];
- // Declaration for the array of characters to lower-case characters.
- ABSL_DLL extern const char kToLower[256];
- } // namespace ascii_internal
- // ascii_isalpha()
- //
- // Determines whether the given character is an alphabetic character.
- inline bool ascii_isalpha(unsigned char c) {
- return (ascii_internal::kPropertyBits[c] & 0x01) != 0;
- }
- // ascii_isalnum()
- //
- // Determines whether the given character is an alphanumeric character.
- inline bool ascii_isalnum(unsigned char c) {
- return (ascii_internal::kPropertyBits[c] & 0x04) != 0;
- }
- // ascii_isspace()
- //
- // Determines whether the given character is a whitespace character (space,
- // tab, vertical tab, formfeed, linefeed, or carriage return).
- inline bool ascii_isspace(unsigned char c) {
- return (ascii_internal::kPropertyBits[c] & 0x08) != 0;
- }
- // ascii_ispunct()
- //
- // Determines whether the given character is a punctuation character.
- inline bool ascii_ispunct(unsigned char c) {
- return (ascii_internal::kPropertyBits[c] & 0x10) != 0;
- }
- // ascii_isblank()
- //
- // Determines whether the given character is a blank character (tab or space).
- inline bool ascii_isblank(unsigned char c) {
- return (ascii_internal::kPropertyBits[c] & 0x20) != 0;
- }
- // ascii_iscntrl()
- //
- // Determines whether the given character is a control character.
- inline bool ascii_iscntrl(unsigned char c) {
- return (ascii_internal::kPropertyBits[c] & 0x40) != 0;
- }
- // ascii_isxdigit()
- //
- // Determines whether the given character can be represented as a hexadecimal
- // digit character (i.e. {0-9} or {A-F}).
- inline bool ascii_isxdigit(unsigned char c) {
- return (ascii_internal::kPropertyBits[c] & 0x80) != 0;
- }
- // ascii_isdigit()
- //
- // Determines whether the given character can be represented as a decimal
- // digit character (i.e. {0-9}).
- inline bool ascii_isdigit(unsigned char c) { return c >= '0' && c <= '9'; }
- // ascii_isprint()
- //
- // Determines whether the given character is printable, including whitespace.
- inline bool ascii_isprint(unsigned char c) { return c >= 32 && c < 127; }
- // ascii_isgraph()
- //
- // Determines whether the given character has a graphical representation.
- inline bool ascii_isgraph(unsigned char c) { return c > 32 && c < 127; }
- // ascii_isupper()
- //
- // Determines whether the given character is uppercase.
- inline bool ascii_isupper(unsigned char c) { return c >= 'A' && c <= 'Z'; }
- // ascii_islower()
- //
- // Determines whether the given character is lowercase.
- inline bool ascii_islower(unsigned char c) { return c >= 'a' && c <= 'z'; }
- // ascii_isascii()
- //
- // Determines whether the given character is ASCII.
- inline bool ascii_isascii(unsigned char c) { return c < 128; }
- // ascii_tolower()
- //
- // Returns an ASCII character, converting to lowercase if uppercase is
- // passed. Note that character values > 127 are simply returned.
- inline char ascii_tolower(unsigned char c) {
- return ascii_internal::kToLower[c];
- }
- // Converts the characters in `s` to lowercase, changing the contents of `s`.
- void AsciiStrToLower(std::string* s);
- // Creates a lowercase string from a given absl::string_view.
- ABSL_MUST_USE_RESULT inline std::string AsciiStrToLower(absl::string_view s) {
- std::string result(s);
- absl::AsciiStrToLower(&result);
- return result;
- }
- // ascii_toupper()
- //
- // Returns the ASCII character, converting to upper-case if lower-case is
- // passed. Note that characters values > 127 are simply returned.
- inline char ascii_toupper(unsigned char c) {
- return ascii_internal::kToUpper[c];
- }
- // Converts the characters in `s` to uppercase, changing the contents of `s`.
- void AsciiStrToUpper(std::string* s);
- // Creates an uppercase string from a given absl::string_view.
- ABSL_MUST_USE_RESULT inline std::string AsciiStrToUpper(absl::string_view s) {
- std::string result(s);
- absl::AsciiStrToUpper(&result);
- return result;
- }
- // Returns absl::string_view with whitespace stripped from the beginning of the
- // given string_view.
- ABSL_MUST_USE_RESULT inline absl::string_view StripLeadingAsciiWhitespace(
- absl::string_view str) {
- auto it = std::find_if_not(str.begin(), str.end(), absl::ascii_isspace);
- return str.substr(it - str.begin());
- }
- // Strips in place whitespace from the beginning of the given string.
- inline void StripLeadingAsciiWhitespace(std::string* str) {
- auto it = std::find_if_not(str->begin(), str->end(), absl::ascii_isspace);
- str->erase(str->begin(), it);
- }
- // Returns absl::string_view with whitespace stripped from the end of the given
- // string_view.
- ABSL_MUST_USE_RESULT inline absl::string_view StripTrailingAsciiWhitespace(
- absl::string_view str) {
- auto it = std::find_if_not(str.rbegin(), str.rend(), absl::ascii_isspace);
- return str.substr(0, str.rend() - it);
- }
- // Strips in place whitespace from the end of the given string
- inline void StripTrailingAsciiWhitespace(std::string* str) {
- auto it = std::find_if_not(str->rbegin(), str->rend(), absl::ascii_isspace);
- str->erase(str->rend() - it);
- }
- // Returns absl::string_view with whitespace stripped from both ends of the
- // given string_view.
- ABSL_MUST_USE_RESULT inline absl::string_view StripAsciiWhitespace(
- absl::string_view str) {
- return StripTrailingAsciiWhitespace(StripLeadingAsciiWhitespace(str));
- }
- // Strips in place whitespace from both ends of the given string
- inline void StripAsciiWhitespace(std::string* str) {
- StripTrailingAsciiWhitespace(str);
- StripLeadingAsciiWhitespace(str);
- }
- // Removes leading, trailing, and consecutive internal whitespace.
- void RemoveExtraAsciiWhitespace(std::string*);
- ABSL_NAMESPACE_END
- } // namespace absl
- #endif // ABSL_STRINGS_ASCII_H_
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