// // 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 // // http://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/strings/string_view.h" namespace absl { namespace ascii_internal { // Declaration for an array of bitfields holding character information. extern const unsigned char kPropertyBits[256]; // Declaration for the array of characters to upper-case characters. extern const char kToUpper[256]; // Declaration for the array of characters to lower-case characters. 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 std::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 std::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 absl::string_view(it, str.end() - it); } // Strips in place whitespace from the beginning of the given std::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 absl::string_view(str.begin(), str.rend() - it); } // Strips in place whitespace from the end of the given std::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 std::string inline void StripAsciiWhitespace(std::string* str) { StripTrailingAsciiWhitespace(str); StripLeadingAsciiWhitespace(str); } // Removes leading, trailing, and consecutive internal whitespace. void RemoveExtraAsciiWhitespace(std::string*); } // namespace absl #endif // ABSL_STRINGS_ASCII_H_