text: /*
   * Copyright (c) Facebook, Inc. and its affiliates.
   *
   * 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.
   */
  
  #pragma once
  #define FOLLY_STRING_H_
  
  #include <cstdarg>
  #include <exception>
  #include <string>
  #include <unordered_map>
  #include <unordered_set>
  #include <vector>
  
  #include <folly/Conv.h>
  #include <folly/ExceptionString.h>
  #include <folly/Portability.h>
  #include <folly/Range.h>
  #include <folly/ScopeGuard.h>
  #include <folly/Traits.h>
  
  namespace folly {
  
  /**
   * C-Escape a string, making it suitable for representation as a C string
   * literal.  Appends the result to the output string.
   *
   * Backslashes all occurrences of backslash and double-quote:
   *   "  ->  \"
   *   \  ->  \\
   *
   * Replaces all non-printable ASCII characters with backslash-octal
   * representation:
   *   <ASCII 254> -> \376
   *
   * Note that we use backslash-octal instead of backslash-hex because the octal
   * representation is guaranteed to consume no more than 3 characters; "\3760"
   * represents two characters, one with value 254, and one with value 48 ('0'),
   * whereas "\xfe0" represents only one character (with value 4064, which leads
   * to implementation-defined behavior).
   */
  template <class String>
  void cEscape(StringPiece str, String& out);
  
  /**
   * Similar to cEscape above, but returns the escaped string.
   */
  template <class String>
  String cEscape(StringPiece str) {
    String out;
    cEscape(str, out);
    return out;
  }
  
  /**
   * C-Unescape a string; the opposite of cEscape above.  Appends the result
   * to the output string.
   *
   * Recognizes the standard C escape sequences:
   *
   * \code
   * \' \" \? \\ \a \b \f \n \r \t \v
   * \[0-7]+
   * \x[0-9a-fA-F]+
   * \endcode
   *
   * In strict mode (default), throws std::invalid_argument if it encounters
   * an unrecognized escape sequence.  In non-strict mode, it leaves
   * the escape sequence unchanged.
   */
  template <class String>
  void cUnescape(StringPiece str, String& out, bool strict = true);
  
  /**
   * Similar to cUnescape above, but returns the escaped string.
   */
  template <class String>
  String cUnescape(StringPiece str, bool strict = true) {
    String out;
    cUnescape(str, out, strict);
    return out;
  }
  
  /**
   * URI-escape a string.  Appends the result to the output string.
   *
   * Alphanumeric characters and other characters marked as "unreserved" in RFC
   * 3986 ( -_.~ ) are left unchanged.  In PATH mode, the forward slash (/) is
   * also left unchanged.  In QUERY mode, spaces are replaced by '+'.  All other
   * characters are percent-encoded.
   */
  enum class UriEscapeMode : unsigned char {
    // The values are meaningful, see generate_escape_tables.py
    ALL = 0,
    QUERY = 1,
    PATH = 2
  };
  template <class String>
  void uriEscape(
      StringPiece str,
      String& out,
      UriEscapeMode mode = UriEscapeMode::ALL);
  
  /**
   * Similar to uriEscape above, but returns the escaped string.
   */
  template <class String>
  String uriEscape(StringPiece str, UriEscapeMode mode = UriEscapeMode::ALL) {
    String out;
    uriEscape(str, out, mode);
    return out;
  }
  
  /**
   * URI-unescape a string.  Appends the result to the output string.
   *
   * In QUERY mode, '+' are replaced by space.  %XX sequences are decoded if
   * XX is a valid hex sequence, otherwise we throw invalid_argument.
   */
  template <class String>
  void uriUnescape(
      StringPiece str,
      String& out,
      UriEscapeMode mode = UriEscapeMode::ALL);
  
  /**
   * Similar to uriUnescape above, but returns the unescaped string.
   */
  template <class String>
  String uriUnescape(StringPiece str, UriEscapeMode mode = UriEscapeMode::ALL) {
    String out;
    uriUnescape(str, out, mode);
    return out;
  }
  
  /**
   * stringPrintf is much like printf but deposits its result into a
   * string. Two signatures are supported: the first simply returns the
   * resulting string, and the second appends the produced characters to
   * the specified string and returns a reference to it.
   */
  std::string stringPrintf(FOLLY_PRINTF_FORMAT const char* format, ...)
      FOLLY_PRINTF_FORMAT_ATTR(1, 2);
  
  /* Similar to stringPrintf, with different signature. */
  void stringPrintf(std::string* out, FOLLY_PRINTF_FORMAT const char* format, ...)
      FOLLY_PRINTF_FORMAT_ATTR(2, 3);
  
  std::string& stringAppendf(
      std::string* output,
      FOLLY_PRINTF_FORMAT const char* format,
      ...) FOLLY_PRINTF_FORMAT_ATTR(2, 3);
  
  /**
   * Similar to stringPrintf, but accepts a va_list argument.
   *
   * As with vsnprintf() itself, the value of ap is undefined after the call.
   * These functions do not call va_end() on ap.
   */
  std::string stringVPrintf(const char* format, va_list ap);
  void stringVPrintf(std::string* out, const char* format, va_list ap);
  std::string& stringVAppendf(std::string* out, const char* format, va_list ap);
  
  /**
   * Backslashify a string, that is, replace non-printable characters
   * with C-style (but NOT C compliant) "\xHH" encoding.  If hex_style
   * is false, then shorthand notations like "\0" will be used instead
   * of "\x00" for the most common backslash cases.
   *
   * There are two forms, one returning the input string, and one
   * creating output in the specified output string.
   *
   * This is mainly intended for printing to a terminal, so it is not
   * particularly optimized.
   *
   * Do *not* use this in situations where you expect to be able to feed
   * the string to a C or C++ compiler, as there are nuances with how C
   * parses such strings that lead to failures.  This is for display
   * purposed only.  If you want a string you can embed for use in C or
   * C++, use cEscape instead.  This function is for display purposes
   * only.
   */
  template <class OutputString>
  void backslashify(
      folly::StringPiece input,
      OutputString& output,
      bool hex_style = false);
  
  template <class OutputString = std::string>
  OutputString backslashify(StringPiece input, bool hex_style = false) {
    OutputString output;
    backslashify(input, output, hex_style);
    return output;
  }
  
  /**
   * Take a string and "humanify" it -- that is, make it look better.
   * Since "better" is subjective, caveat emptor.  The basic approach is
   * to count the number of unprintable characters.  If there are none,
   * then the output is the input.  If there are relatively few, or if
   * there is a long "enough" prefix of printable characters, use
   * backslashify.  If it is mostly binary, then simply hex encode.
   *
   * This is an attempt to make a computer smart, and so likely is wrong
   * most of the time.
   */
  template <class String1, class String2>
  void humanify(const String1& input, String2& output);
  
  template <class String>
  String humanify(const String& input) {
    String output;
    humanify(input, output);
    return output;
  }
  
  /**
   * Same functionality as Python's binascii.hexlify.  Returns true
   * on successful conversion.
   *
   * If append_output is true, append data to the output rather than
   * replace it.
   */
  template <class InputString, class OutputString>
  bool hexlify(
      const InputString& input,
      OutputString& output,
      bool append = false);
  
  template <class OutputString = std::string>
  OutputString hexlify(ByteRange input) {
    OutputString output;
    if (!hexlify(input, output)) {
      // hexlify() currently always returns true, so this can't really happen
      throw_exception<std::runtime_error>("hexlify failed");
    }
    return output;
  }
  
  template <class OutputString = std::string>
  OutputString hexlify(StringPiece input) {
    return hexlify<OutputString>(ByteRange{input});
  }
  
  /**
   * Same functionality as Python's binascii.unhexlify.  Returns true
   * on successful conversion.
   */
  template <class InputString, class OutputString>
  bool unhexlify(const InputString& input, OutputString& output);
  
  template <class OutputString = std::string>
  OutputString unhexlify(StringPiece input) {
    OutputString output;
    if (!unhexlify(input, output)) {
      // unhexlify() fails if the input has non-hexidecimal characters,
      // or if it doesn't consist of a whole number of bytes
      throw_exception<std::domain_error>("unhexlify() called with non-hex input");
    }
    return output;
  }
  
  /**
   * A pretty-printer for numbers that appends suffixes of units of the
   * given type.  It prints 4 sig-figs of value with the most
   * appropriate unit.
   *
   * If `addSpace' is true, we put a space between the units suffix and
   * the value.
   *
   * Current types are:
   *   PRETTY_TIME         - s, ms, us, ns, etc.
   *   PRETTY_TIME_HMS     - h, m, s, ms, us, ns, etc.
   *   PRETTY_BYTES_METRIC - kB, MB, GB, etc (goes up by 10^3 = 1000 each time)
   *   PRETTY_BYTES        - kB, MB, GB, etc (goes up by 2^10 = 1024 each time)
   *   PRETTY_BYTES_IEC    - KiB, MiB, GiB, etc
   *   PRETTY_UNITS_METRIC - k, M, G, etc (goes up by 10^3 = 1000 each time)
   *   PRETTY_UNITS_BINARY - k, M, G, etc (goes up by 2^10 = 1024 each time)
   *   PRETTY_UNITS_BINARY_IEC - Ki, Mi, Gi, etc
   *   PRETTY_SI           - full SI metric prefixes from yocto to Yotta
   *                         http://en.wikipedia.org/wiki/Metric_prefix
   *
   * @author Mark Rabkin <mrabkin@fb.com>
   */
  enum PrettyType {
    PRETTY_TIME,
    PRETTY_TIME_HMS,
  
    PRETTY_BYTES_METRIC,
    PRETTY_BYTES_BINARY,
    PRETTY_BYTES = PRETTY_BYTES_BINARY,
    PRETTY_BYTES_BINARY_IEC,
    PRETTY_BYTES_IEC = PRETTY_BYTES_BINARY_IEC,
  
    PRETTY_UNITS_METRIC,
    PRETTY_UNITS_BINARY,
    PRETTY_UNITS_BINARY_IEC,
  
    PRETTY_SI,
    PRETTY_NUM_TYPES,
  };
  
  std::string prettyPrint(double val, PrettyType, bool addSpace = true);
  
  /**
   * This utility converts StringPiece in pretty format (look above) to double,
   * with progress information. Alters the  StringPiece parameter
   * to get rid of the already-parsed characters.
   * Expects string in form <floating point number> {space}* [<suffix>]
   * If string is not in correct format, utility finds longest valid prefix and
   * if there at least one, returns double value based on that prefix and
   * modifies string to what is left after parsing. Throws and std::range_error
   * exception if there is no correct parse.
   * Examples(for PRETTY_UNITS_METRIC):
   * '10M' => 10 000 000
   * '10 M' => 10 000 000
   * '10' => 10
   * '10 Mx' => 10 000 000, prettyString == "x"
   * 'abc' => throws std::range_error
   */
  double prettyToDouble(
      folly::StringPiece* const prettyString,
      const PrettyType type);
  
  /**
   * Same as prettyToDouble(folly::StringPiece*, PrettyType), but
   * expects whole string to be correctly parseable. Throws std::range_error
   * otherwise
   */
  double prettyToDouble(folly::StringPiece prettyString, const PrettyType type);
  
  /**
   * Write a hex dump of size bytes starting at ptr to out.
   *
   * The hex dump is formatted as follows:
   *
   * for the string "abcdefghijklmnopqrstuvwxyz\x02"
  00000000  61 62 63 64 65 66 67 68  69 6a 6b 6c 6d 6e 6f 70  |abcdefghijklmnop|
  00000010  71 72 73 74 75 76 77 78  79 7a 02                 |qrstuvwxyz.     |
   *
   * that is, we write 16 bytes per line, both as hex bytes and as printable
   * characters.  Non-printable characters are replaced with '.'
   * Lines are written to out one by one (one StringPiece at a time) without
   * delimiters.
   */
  template <class OutIt>
  void hexDump(const void* ptr, size_t size, OutIt out);
  
  /**
   * Return the hex dump of size bytes starting at ptr as a string.
   */
  std::string hexDump(const void* ptr, size_t size);
  
  /**
   * Return a string containing the description of the given errno value.
   * Takes care not to overwrite the actual system errno, so calling
   * errnoStr(errno) is valid.
   */
  std::string errnoStr(int err);
  
  /*
   * Split a string into a list of tokens by delimiter.
   *
   * The split interface here supports different output types, selected
   * at compile time: StringPiece, fbstring, or std::string.  If you are
   * using a vector to hold the output, it detects the type based on
   * what your vector contains.  If the output vector is not empty, split
   * will append to the end of the vector.
   *
   * You can also use splitTo() to write the output to an arbitrary
   * OutputIterator (e.g. std::inserter() on a std::set<>), in which
   * case you have to tell the function the type.  (Rationale:
   * OutputIterators don't have a value_type, so we can't detect the
   * type in splitTo without being told.)
   *
   * Examples:
   *
   *   std::vector<folly::StringPiece> v;
   *   folly::split(":", "asd:bsd", v);
   *
   *   std::set<StringPiece> s;
   *   folly::splitTo<StringPiece>(":", "asd:bsd:asd:csd",
   *    std::inserter(s, s.begin()));
   *
   * Split also takes a flag (ignoreEmpty) that indicates whether adjacent
   * delimiters should be treated as one single separator (ignoring empty tokens)
   * or not (generating empty tokens).
   */
  
  template <class Delim, class String, class OutputType>
  void split(
      const Delim& delimiter,
      const String& input,
      std::vector<OutputType>& out,
      const bool ignoreEmpty = false);
  
  template <class T, class Allocator>
  class fbvector;
  
  template <class Delim, class String, class OutputType>
  void split(
      const Delim& delimiter,
      const String& input,
      folly::fbvector<OutputType, std::allocator<OutputType>>& out,
      const bool ignoreEmpty = false);
  
  template <
      class OutputValueType,
      class Delim,
      class String,
      class OutputIterator>
  void splitTo(
      const Delim& delimiter,
      const String& input,
      OutputIterator out,
      const bool ignoreEmpty = false);
  
  /*
   * Split a string into a fixed number of string pieces and/or numeric types
   * by delimiter. Conversions are supported for any type which folly:to<> can
   * target, including all overloads of parseTo(). Returns 'true' if the fields
   * were all successfully populated.  Returns 'false' if there were too few
   * fields in the input, or too many fields if exact=true.  Casting exceptions
   * will not be caught.
   *
   * Examples:
   *
   *  folly::StringPiece name, key, value;
   *  if (folly::split('\t', line, name, key, value))
   *    ...
   *
   *  folly::StringPiece name;
   *  double value;
   *  int id;
   *  if (folly::split('\t', line, name, value, id))
   *    ...
   *
   * The 'exact' template parameter specifies how the function behaves when too
   * many fields are present in the input string. When 'exact' is set to its
   * default value of 'true', a call to split will fail if the number of fields in
   * the input string does not exactly match the number of output parameters
   * passed. If 'exact' is overridden to 'false', all remaining fields will be
   * stored, unsplit, in the last field, as shown below:
   *
   *  folly::StringPiece x, y.
   *  if (folly::split<false>(':', "a:b:c", x, y))
   *    assert(x == "a" && y == "b:c");
   *
   * Note that this will likely not work if the last field's target is of numeric
   * type, in which case folly::to<> will throw an exception.
   */
  namespace detail {
  template <typename Void, typename OutputType>
  struct IsConvertible : std::false_type {};
  
  template <>
  struct IsConvertible<void, decltype(std::ignore)> : std::true_type {};
  
  template <typename OutputType>
  struct IsConvertible<
      void_t<decltype(parseTo(StringPiece{}, std::declval<OutputType&>()))>,
      OutputType> : std::true_type {};
  } // namespace detail
  template <typename OutputType>
  struct IsConvertible : detail::IsConvertible<void, OutputType> {};
  
  template <bool exact = true, class Delim, class... OutputTypes>
  typename std::enable_if<
      StrictConjunction<IsConvertible<OutputTypes>...>::value &&
          sizeof...(OutputTypes) >= 1,
      bool>::type
  split(const Delim& delimiter, StringPiece input, OutputTypes&... outputs);
  
  /*
   * Join list of tokens.
   *
   * Stores a string representation of tokens in the same order with
   * deliminer between each element.
   */
  
  template <class Delim, class Iterator, class String>
  void join(const Delim& delimiter, Iterator begin, Iterator end, String& output);
  
  template <class Delim, class Container, class String>
  void join(const Delim& delimiter, const Container& container, String& output) {
    join(delimiter, container.begin(), container.end(), output);
  }
  
  template <class Delim, class Value, class String>
  void join(
      const Delim& delimiter,
      const std::initializer_list<Value>& values,
      String& output) {
    join(delimiter, values.begin(), values.end(), output);
  }
  
  template <class Delim, class Container>
  std::string join(const Delim& delimiter, const Container& container) {
    std::string output;
    join(delimiter, container.begin(), container.end(), output);
    return output;
  }
  
  template <class Delim, class Value>
  std::string join(
      const Delim& delimiter,
      const std::initializer_list<Value>& values) {
    std::string output;
    join(delimiter, values.begin(), values.end(), output);
    return output;
  }
  
  template <
      class Delim,
      class Iterator,
      typename std::enable_if<std::is_base_of<
          std::forward_iterator_tag,
          typename std::iterator_traits<Iterator>::iterator_category>::value>::
          type* = nullptr>
  std::string join(const Delim& delimiter, Iterator begin, Iterator end) {
    std::string output;
    join(delimiter, begin, end, output);
    return output;
  }
  
  /**
   * Returns a subpiece with all whitespace removed from the front of @sp.
   * Whitespace means any of [' ', '\n', '\r', '\t'].
   */
  StringPiece ltrimWhitespace(StringPiece sp);
  
  /**
   * Returns a subpiece with all whitespace removed from the back of @sp.
   * Whitespace means any of [' ', '\n', '\r', '\t'].
   */
  StringPiece rtrimWhitespace(StringPiece sp);
  
  /**
   * Returns a subpiece with all whitespace removed from the back and front of
   * @sp. Whitespace means any of [' ', '\n', '\r', '\t'].
   */
  inline StringPiece trimWhitespace(StringPiece sp) {
    return ltrimWhitespace(rtrimWhitespace(sp));
  }
  
  /**
   * Returns a subpiece with all whitespace removed from the front of @sp.
   * Whitespace means any of [' ', '\n', '\r', '\t'].
   * DEPRECATED: @see ltrimWhitespace @see rtrimWhitespace
   */
  inline StringPiece skipWhitespace(StringPiece sp) {
    return ltrimWhitespace(sp);
  }
  
  /**
   * Returns a subpiece with all characters the provided @toTrim returns true
   * for removed from the front of @sp.
   */
  template <typename ToTrim>
  StringPiece ltrim(StringPiece sp, ToTrim toTrim) {
    while (!sp.empty() && toTrim(sp.front())) {
      sp.pop_front();
    }
  
    return sp;
  }
  
  /**
   * Returns a subpiece with all characters the provided @toTrim returns true
   * for removed from the back of @sp.
   */
  template <typename ToTrim>
  StringPiece rtrim(StringPiece sp, ToTrim toTrim) {
    while (!sp.empty() && toTrim(sp.back())) {
      sp.pop_back();
    }
  
    return sp;
  }
  
  /**
   * Returns a subpiece with all characters the provided @toTrim returns true
   * for removed from the back and front of @sp.
   */
  template <typename ToTrim>
  StringPiece trim(StringPiece sp, ToTrim toTrim) {
    return ltrim(rtrim(sp, std::ref(toTrim)), std::ref(toTrim));
  }
  
  /**
   *  Strips the leading and the trailing whitespace-only lines. Then looks for
   *  the least indented non-whitespace-only line and removes its amount of
   *  leading whitespace from every line. Assumes leading whitespace is either all
   *  spaces or all tabs.
   *
   *  Purpose: including a multiline string literal in source code, indented to
   *  the level expected from context.
   */
  std::string stripLeftMargin(std::string s);
  
  /**
   * Fast, in-place lowercasing of ASCII alphabetic characters in strings.
   * Leaves all other characters unchanged, including those with the 0x80
   * bit set.
   * @param str String to convert
   * @param length Length of str, in bytes
   */
  void toLowerAscii(char* str, size_t length);
  
  inline void toLowerAscii(MutableStringPiece str) {
    toLowerAscii(str.begin(), str.size());
  }
  
  inline void toLowerAscii(std::string& str) {
    // str[0] is legal also if the string is empty.
    toLowerAscii(&str[0], str.size());
  }
  
  } // namespace folly
  
  #include <folly/String-inl.h>
  