// Copyright 2008 and onwards Google, Inc.

//

// #status: RECOMMENDED

// #category: operations on strings

// #summary: Functions for splitting strings into substrings.

//

// This file contains functions for splitting strings. The new and recommended

// API for string splitting is the strings::Split() function. The old API is a

// large collection of standalone functions declared at the bottom of this file

// in the global scope.

//

// TODO(user): Rough migration plan from old API to new API

// (1) Add comments to old Split*() functions showing how to do the same things

//     with the new API.

// (2) Reimplement some of the old Split*() functions in terms of the new

//     Split() API. This will allow deletion of code in split.cc.

// (3) (Optional) Replace old Split*() API calls at call sites with calls to new

//     Split() API.

//

#pragma once

// IWYU pragma: no_include <pstl/glue_algorithm_defs.h>

#include <stddef.h>

#include <algorithm>

using std::copy;

using std::max;

using std::min;

using std::reverse;

using std::sort;

using std::swap;

#include <iterator>

using std::back_insert_iterator;

using std::iterator_traits;

#include <map>

using std::map;

using std::multimap;

#include <set>

using std::multiset;

using std::set;

#include <string>

using std::string;

#include <utility>

using std::make_pair;

using std::pair;

#include <vector>

using std::vector;

#include "common/logging.h"

#include <unordered_map>

#include <unordered_set>

#include "gutil/integral_types.h"

#include "gutil/strings/charset.h"

#include "gutil/strings/stringpiece.h"

#include "gutil/strings/strip.h"

#include "gutil/strings/split_internal.h" // IWYU pragma: keep

namespace strings {

//                              The new Split API

//                                  aka Split2

//                              aka strings::Split()

//

// This string splitting API consists of a Split() function in the ::strings

// namespace and a handful of delimiter objects in the ::strings::delimiter

// namespace (more on delimiter objects below). The Split() function always

// takes two arguments: the text to be split and the delimiter on which to split

// the text. An optional third argument may also be given, which is a Predicate

// functor that will be used to filter the results, e.g., to skip empty strings

// (more on predicates below). The Split() function adapts the returned

// collection to the type specified by the caller.

//

// Example 1:

//   // Splits the given string on commas. Returns the results in a

//   // vector of strings.

//   vector<string> v = strings::Split("a,b,c", ",");

//   assert(v.size() == 3);

//

// Example 2:

//   // By default, empty strings are *included* in the output. See the

//   // strings::SkipEmpty predicate below to omit them.

//   vector<string> v = strings::Split("a,b,,c", ",");

//   assert(v.size() == 4);  // "a", "b", "", "c"

//   v = strings::Split("", ",");

//   assert(v.size() == 1);  // v contains a single ""

//

// Example 3:

//   // Splits the string as in the previous example, except that the results

//   // are returned as StringPiece objects. Note that because we are storing

//   // the results within StringPiece objects, we have to ensure that the input

//   // string outlives any results.

//   vector<StringPiece> v = strings::Split("a,b,c", ",");

//   assert(v.size() == 3);

//

// Example 4:

//   // Stores results in a set<string>.

//   set<string> a = strings::Split("a,b,c,a,b,c", ",");

//   assert(a.size() == 3);

//

// Example 5:

//   // Stores results in a map. The map implementation assumes that the input

//   // is provided as a series of key/value pairs. For example, the 0th element

//   // resulting from the split will be stored as a key to the 1st element. If

//   // an odd number of elements are resolved, the last element is paired with

//   // a default-constructed value (e.g., empty string).

//   map<string, string> m = strings::Split("a,b,c", ",");

//   assert(m.size() == 2);

//   assert(m["a"] == "b");

//   assert(m["c"] == "");  // last component value equals ""

//

// Example 6:

//   // Splits on the empty string, which results in each character of the input

//   // string becoming one element in the output collection.

//   vector<string> v = strings::Split("abc", "");

//   assert(v.size() == 3);

//

// Example 7:

//   // Stores first two split strings as the members in an std::pair.

//   std::pair<string, string> p = strings::Split("a,b,c", ",");

//   EXPECT_EQ("a", p.first);

//   EXPECT_EQ("b", p.second);

//   // "c" is omitted because std::pair can hold only two elements.

//

// As illustrated above, the Split() function adapts the returned collection to

// the type specified by the caller. The returned collections may contain

// string, StringPiece, Cord, or any object that has a constructor (explicit or

// not) that takes a single StringPiece argument. This pattern works for all

// standard STL containers including vector, list, deque, set, multiset, map,

// multimap, unordered_set and unordered_map, and even std::pair which is not

// actually a container.

//

// Splitting to std::pair is an interesting case because it can hold only two

// elements and is not a collection type. When splitting to an std::pair the

// first two split strings become the std::pair's .first and .second members

// respectively. The remaining split substrings are discarded. If there are less

// than two split substrings, the empty string is used for the corresponding

// std::pair member.

//

// The strings::Split() function can be used multiple times to perform more

// complicated splitting logic, such as intelligently parsing key-value pairs.

// For example

//

//   // The input string "a=b=c,d=e,f=,g" becomes

//   // { "a" => "b=c", "d" => "e", "f" => "", "g" => "" }

//   map<string, string> m;

//   for (StringPiece sp : strings::Split("a=b=c,d=e,f=,g", ",")) {

//     m.insert(strings::Split(sp, strings::delimiter::Limit("=", 1)));

//   }

//   EXPECT_EQ("b=c", m.find("a")->second);

//   EXPECT_EQ("e", m.find("d")->second);

//   EXPECT_EQ("", m.find("f")->second);

//   EXPECT_EQ("", m.find("g")->second);

//

// The above example stores the results in an std::map. But depending on your

// data requirements, you can just as easily store the results in an

// std::multimap or even a vector<std::pair<>>.

//

//

//                                  Delimiters

//

// The Split() function also takes a second argument that is a delimiter. This

// delimiter is actually an object that defines the boundaries between elements

// in the provided input. If a string (const char*, ::string, or StringPiece) is

// passed in place of an explicit Delimiter object, the argument is implicitly

// converted to a ::strings::delimiter::Literal.

//

// With this split API comes the formal concept of a Delimiter (big D). A

// Delimiter is an object with a Find() function that knows how find the first

// occurrence of itself in a given StringPiece. Models of the Delimiter concept

// represent specific kinds of delimiters, such as single characters,

// substrings, or even regular expressions.

//

// The following Delimiter objects are provided as part of the Split() API:

//

//   - Literal (default)

//   - AnyOf

//   - Limit

//

// The following are examples of using some provided Delimiter objects:

//

// Example 1:

//   // Because a string literal is converted to a strings::delimiter::Literal,

//   // the following two splits are equivalent.

//   vector<string> v1 = strings::Split("a,b,c", ",");           // (1)

//   using ::strings::delimiter::Literal;

//   vector<string> v2 = strings::Split("a,b,c", Literal(","));  // (2)

//

// Example 2:

//   // Splits on any of the characters specified in the delimiter string.

//   using ::strings::delimiter::AnyOf;

//   vector<string> v = strings::Split("a,b;c-d", AnyOf(",;-"));

//   assert(v.size() == 4);

//

// Example 3:

//   // Uses the Limit meta-delimiter to limit the number of matches a delimiter

//   // can have. In this case, the delimiter of a Literal comma is limited to

//   // to matching at most one time. The last element in the returned

//   // collection will contain all unsplit pieces, which may contain instances

//   // of the delimiter.

//   using ::strings::delimiter::Limit;

//   vector<string> v = strings::Split("a,b,c", Limit(",", 1));

//   assert(v.size() == 2);  // Limited to 1 delimiter; so two elements found

//   assert(v[0] == "a");

//   assert(v[1] == "b,c");

//

//

//                                  Predicates

//

// Predicates can filter the results of a Split() operation by determining

// whether or not a resultant element is included in the result set. A predicate

// may be passed as an *optional* third argument to the Split() function.

//

// Predicates are unary functions (or functors) that take a single StringPiece

// argument and return bool indicating whether the argument should be included

// (true) or excluded (false).

//

// One example where this is useful is when filtering out empty substrings. By

// default, empty substrings may be returned by strings::Split(), which is

// similar to the way split functions work in other programming languages. For

// example:

//

//   // Empty strings *are* included in the returned collection.

//   vector<string> v = strings::Split(",a,,b,", ",");

//   assert(v.size() ==  5);  // v[0] == "", v[1] == "a", v[2] == "", ...

//

// These empty strings can be filtered out of the results by simply passing the

// provided SkipEmpty predicate as the third argument to the Split() function.

// SkipEmpty does not consider a string containing all whitespace to be empty.

// For that behavior use the SkipWhitespace predicate. For example:

//

// Example 1:

//   // Uses SkipEmpty to omit empty strings. Strings containing whitespace are

//   // not empty and are therefore not skipped.

//   using strings::SkipEmpty;

//   vector<string> v = strings::Split(",a, ,b,", ",", SkipEmpty());

//   assert(v.size() == 3);

//   assert(v[0] == "a");

//   assert(v[1] == " ");  // <-- The whitespace makes the string not empty.

//   assert(v[2] == "b");

//

// Example 2:

//   // Uses SkipWhitespace to skip all strings that are either empty or contain

//   // only whitespace.

//   using strings::SkipWhitespace;

//   vector<string> v = strings::Split(",a, ,b,", ",",  SkipWhitespace());

//   assert(v.size() == 2);

//   assert(v[0] == "a");

//   assert(v[1] == "b");

//

//

//                     Differences between Split1 and Split2

//

// Split2 is the strings::Split() API described above. Split1 is a name for the

// collection of legacy Split*() functions declared later in this file. Most of

// the Split1 functions follow a set of conventions that don't necessarily match

// the conventions used in Split2. The following are some of the important

// differences between Split1 and Split2:

//

// Split1 -> Split2

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

// Append -> Assign:

//   The Split1 functions all returned their output collections via a pointer to

//   an out parameter as is typical in Google code. In some cases the comments

//   explicitly stated that results would be *appended* to the output

//   collection. In some cases it was ambiguous whether results were appended.

//   This ambiguity is gone in the Split2 API as results are always assigned to

//   the output collection, never appended.

//

// AnyOf -> Literal:

//   Most Split1 functions treated their delimiter argument as a string of

//   individual byte delimiters. For example, a delimiter of ",;" would split on

//   "," and ";", not the substring ",;". This behavior is equivalent to the

//   Split2 delimiter strings::delimiter::AnyOf, which is *not* the default. By

//   default, strings::Split() splits using strings::delimiter::Literal() which

//   would treat the whole string ",;" as a single delimiter string.

//

// SkipEmpty -> allow empty:

//   Most Split1 functions omitted empty substrings in the results. To keep

//   empty substrings one would have to use an explicitly named

//   Split*AllowEmpty() function. This behavior is reversed in Split2. By

//   default, strings::Split() *allows* empty substrings in the output. To skip

//   them, use the strings::SkipEmpty predicate.

//

// string -> user's choice:

//   Most Split1 functions return collections of string objects. Some return

//   char*, but the type returned is dictated by each Split1 function. With

//   Split2 the caller can choose which string-like object to return. (Note:

//   char* C-strings are not supported in Split2--use StringPiece instead).

//

// Definitions of the main Split() function.

template <typename Delimiter>

internal::Splitter<Delimiter> Split(StringPiece text, Delimiter d) {

    return internal::Splitter<Delimiter>(text, d);

}

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internal::Splitter<Delimiter> Split(StringPiece text, Delimiter d) {

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    return internal::Splitter<Delimiter>(text, d);

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}

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template <typename Delimiter, typename Predicate>

internal::Splitter<Delimiter, Predicate> Split(StringPiece text, Delimiter d, Predicate p) {

    return internal::Splitter<Delimiter, Predicate>(text, d, p);

}

namespace delimiter {

// A Delimiter object represents a single separator, such as a character,

// literal string, or regular expression. A Delimiter object must have the

// following member:

//

//   StringPiece Find(StringPiece text);

//

// This Find() member function should return a StringPiece referring to the next

// occurrence of the represented delimiter within the given string text. If no

// delimiter is found in the given text, a zero-length StringPiece referring to

// text.end() should be returned (e.g., StringPiece(text.end(), 0)). It is

// important that the returned StringPiece always be within the bounds of the

// StringPiece given as an argument--it must not refer to a string that is

// physically located outside of the given string. The following example is a

// simple Delimiter object that is created with a single char and will look for

// that char in the text given to the Find() function:

//

//   struct SimpleDelimiter {

//     const char c_;

//     explicit SimpleDelimiter(char c) : c_(c) {}

//     StringPiece Find(StringPiece text) {

//       int pos = text.find(c_);

//       if (pos == StringPiece::npos) return StringPiece(text.end(), 0);

//       return StringPiece(text, pos, 1);

//     }

//   };

// Represents a literal string delimiter. Examples:

//

//   using ::strings::delimiter::Literal;

//   vector<string> v = strings::Split("a=>b=>c", Literal("=>"));

//   assert(v.size() == 3);

//   assert(v[0] == "a");

//   assert(v[1] == "b");

//   assert(v[2] == "c");

//

// The next example uses the empty string as a delimiter.

//

//   using ::strings::delimiter::Literal;

//   vector<string> v = strings::Split("abc", Literal(""));

//   assert(v.size() == 3);

//   assert(v[0] == "a");

//   assert(v[1] == "b");

//   assert(v[2] == "c");

//

class Literal {

public:

    explicit Literal(StringPiece sp);

    StringPiece Find(StringPiece text) const;

private:

    const string delimiter_;

};

// Represents a delimiter that will match any of the given byte-sized

// characters. AnyOf is similar to Literal, except that AnyOf uses

// StringPiece::find_first_of() and Literal uses StringPiece::find(). AnyOf

// examples:

//

//   using ::strings::delimiter::AnyOf;

//   vector<string> v = strings::Split("a,b=c", AnyOf(",="));

//

//   assert(v.size() == 3);

//   assert(v[0] == "a");

//   assert(v[1] == "b");

//   assert(v[2] == "c");

//

// If AnyOf is given the empty string, it behaves exactly like Literal and

// matches each individual character in the input string.

//

// Note: The string passed to AnyOf is assumed to be a string of single-byte

// ASCII characters. AnyOf does not work with multi-byte characters.

class AnyOf {

public:

    explicit AnyOf(StringPiece sp);

    StringPiece Find(StringPiece text) const;

private:

    const string delimiters_;

};

// Wraps another delimiter and sets a max number of matches for that delimiter.

// Create LimitImpls using the Limit() function. Example:

//

//   using ::strings::delimiter::Limit;

//   vector<string> v = strings::Split("a,b,c,d", Limit(",", 2));

//

//   assert(v.size() == 3);  // Split on 2 commas, giving a vector with 3 items

//   assert(v[0] == "a");

//   assert(v[1] == "b");

//   assert(v[2] == "c,d");

//

template <typename Delimiter>

class LimitImpl {

public:

    LimitImpl(Delimiter delimiter, int limit)

            : delimiter_(std::move(delimiter)), limit_(limit), count_(0) {}

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            : delimiter_(std::move(delimiter)), limit_(limit), count_(0) {}

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    StringPiece Find(StringPiece text) {

        if (count_++ == limit_) {

            return StringPiece(text.end(), 0); // No more matches.

        }

        return delimiter_.Find(text);

    }

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    StringPiece Find(StringPiece text) {

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        if (count_++ == limit_) {

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            return StringPiece(text.end(), 0); // No more matches.

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        }

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        return delimiter_.Find(text);

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    }

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private:

    Delimiter delimiter_;

    const int limit_;

    int count_;

};

// Overloaded Limit() function to create LimitImpl<> objects. Uses the Delimiter

// Literal as the default if string-like objects are passed as the delimiter

// parameter. This is similar to the overloads for Split() below.

template <typename Delimiter>

LimitImpl<Delimiter> Limit(Delimiter delim, int limit) {

    return LimitImpl<Delimiter>(delim, limit);

}

inline LimitImpl<Literal> Limit(const char* s, int limit) {

    return LimitImpl<Literal>(Literal(s), limit);

}

inline LimitImpl<Literal> Limit(const string& s, int limit) {

    return LimitImpl<Literal>(Literal(s), limit);

}

inline LimitImpl<Literal> Limit(StringPiece s, int limit) {

    return LimitImpl<Literal>(Literal(s), limit);

}

} // namespace delimiter

//

// Predicates are functors that return bool indicating whether the given

// StringPiece should be included in the split output. If the predicate returns

// false then the string will be excluded from the output from strings::Split().

//

// Always returns true, indicating that all strings--including empty

// strings--should be included in the split output. This predicate is not

// strictly needed because this is the default behavior of the strings::Split()

// function. But it might be useful at some call sites to make the intent

// explicit.

//

// vector<string> v = Split(" a , ,,b,", ",", AllowEmpty());

// EXPECT_THAT(v, ElementsAre(" a ", " ", "", "b", ""));

struct AllowEmpty {

    bool operator()(StringPiece sp) const { return true; }

};

// Returns false if the given StringPiece is empty, indicating that the

// strings::Split() API should omit the empty string.

//

// vector<string> v = Split(" a , ,,b,", ",", SkipEmpty());

// EXPECT_THAT(v, ElementsAre(" a ", " ", "b"));

struct SkipEmpty {

    bool operator()(StringPiece sp) const { return !sp.empty(); }

};

// Returns false if the given StringPiece is empty or contains only whitespace,

// indicating that the strings::Split() API should omit the string.

//

// vector<string> v = Split(" a , ,,b,", ",", SkipWhitespace());

// EXPECT_THAT(v, ElementsAre(" a ", "b"));

struct SkipWhitespace {

    bool operator()(StringPiece sp) const {

        StripWhiteSpace(&sp);

        return !sp.empty();

    }

};

// Split() function overloads to effectively give Split() a default Delimiter

// type of Literal. If Split() is called and a string is passed as the delimiter

// instead of an actual Delimiter object, then one of these overloads will be

// invoked and will create a Splitter<Literal> with the delimiter string.

//

// Since Split() is a function template above, these overload signatures need to

// be explicit about the string type so they match better than the templated

// version. These functions are overloaded for:

//

//   - const char*

//   - const string&

//   - StringPiece

inline internal::Splitter<delimiter::Literal> Split(StringPiece text, const char* delimiter) {

    return internal::Splitter<delimiter::Literal>(text, delimiter::Literal(delimiter));

}

inline internal::Splitter<delimiter::Literal> Split(StringPiece text, const string& delimiter) {

    return internal::Splitter<delimiter::Literal>(text, delimiter::Literal(delimiter));

}

inline internal::Splitter<delimiter::Literal> Split(StringPiece text, StringPiece delimiter) {

    return internal::Splitter<delimiter::Literal>(text, delimiter::Literal(delimiter));

}

// Same overloads as above, but also including a Predicate argument.

template <typename Predicate>

internal::Splitter<delimiter::Literal, Predicate> Split(StringPiece text, const char* delimiter,

                                                        Predicate p) {

    return internal::Splitter<delimiter::Literal, Predicate>(text, delimiter::Literal(delimiter),

                                                             p);

}

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                                                        Predicate p) {

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    return internal::Splitter<delimiter::Literal, Predicate>(text, delimiter::Literal(delimiter),

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                                                             p);

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}

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template <typename Predicate>

internal::Splitter<delimiter::Literal, Predicate> Split(StringPiece text, const string& delimiter,

                                                        Predicate p) {

    return internal::Splitter<delimiter::Literal, Predicate>(text, delimiter::Literal(delimiter),

                                                             p);

}

template <typename Predicate>

internal::Splitter<delimiter::Literal, Predicate> Split(StringPiece text, StringPiece delimiter,

                                                        Predicate p) {

    return internal::Splitter<delimiter::Literal, Predicate>(text, delimiter::Literal(delimiter),

                                                             p);

}

} // namespace strings

//

// ==================== LEGACY SPLIT FUNCTIONS ====================

//

// NOTE: The instruction below creates a Module titled

// GlobalSplitFunctions within the auto-generated Doxygen documentation.

// This instruction is needed to expose global functions that are not

// within a namespace.

//

// START DOXYGEN SplitFunctions grouping

/* @defgroup SplitFunctions

 * @{ */

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

// ClipString

//    Clip a string to a max length. We try to clip on a word boundary

//    if this is possible. If the string is clipped, we append an

//    ellipsis.

//

//    ***NOTE***

//    ClipString counts length with strlen.  If you have non-ASCII

//    strings like UTF-8, this is wrong.  If you are displaying the

//    clipped strings to users in a frontend, consider using

//    ClipStringOnWordBoundary in

//    webserver/util/snippets/rewriteboldtags, which considers the width

//    of the string, not just the number of bytes.

//

//    TODO(user) Move ClipString back to strutil.  The problem with this is

//    that ClipStringHelper is used behind the scenes by SplitStringToLines, but

//    probably shouldn't be exposed in the .h files.

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

void ClipString(char* str, int max_len);

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

// ClipString

//    Version of ClipString() that uses string instead of char*.

//    NOTE: See comment above.

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

void ClipString(string* full_str, int max_len);

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

// SplitStringToLines() Split a string into lines of maximum length

// 'max_len'. Append the resulting lines to 'result'. Will attempt

// to split on word boundaries.  If 'num_lines'

// is zero it splits up the whole string regardless of length. If

// 'num_lines' is positive, it returns at most num_lines lines, and

// appends a "..." to the end of the last line if the string is too

// long to fit completely into 'num_lines' lines.

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

void SplitStringToLines(const char* full, int max_len, int num_lines, vector<string>* result);

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

// SplitOneStringToken()

//   Returns the first "delim" delimited string from "*source" and modifies

//   *source to point after the delimiter that was found. If no delimiter is

//   found, *source is set to NULL.

//

//   If the start of *source is a delimiter, an empty string is returned.

//   If *source is NULL, an empty string is returned.

//

//   "delim" is treated as a sequence of 1 or more character delimiters. Any one

//   of the characters present in "delim" is considered to be a single

//   delimiter; The delimiter is not "delim" as a whole. For example:

//

//     const char* s = "abc=;de";

//     string r = SplitOneStringToken(&s, ";=");

//     // r = "abc"

//     // s points to ";de"

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

string SplitOneStringToken(const char** source, const char* delim);

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

// SplitUsing()

//    Split a string into substrings based on the nul-terminated list

//    of bytes at delimiters (uses strsep) and return a vector of

//    those strings. Modifies 'full' We allocate the return vector,

//    and you should free it.  Note that empty fields are ignored.

//    Use SplitToVector with last argument 'false' if you want the

//    empty fields.

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

vector<char*>* SplitUsing(char* full, const char* delimiters);

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

// SplitToVector()

//    Split a string into substrings based on the nul-terminated list

//    of bytes at delim (uses strsep) and appends the split

//    strings to 'vec'.  Modifies "full".  If omit empty strings is

//    true, empty strings are omitted from the resulting vector.

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

void SplitToVector(char* full, const char* delimiters, vector<char*>* vec, bool omit_empty_strings);

void SplitToVector(char* full, const char* delimiters, vector<const char*>* vec,

                   bool omit_empty_strings);

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

// SplitStringPieceToVector

//    Split a StringPiece into sub-StringPieces based on the

//    nul-terminated list of bytes at delim and appends the

//    pieces to 'vec'.  If omit empty strings is true, empty strings

//    are omitted from the resulting vector.

//    Expects the original string (from which 'full' is derived) to exist

//    for the full lifespan of 'vec'.

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

void SplitStringPieceToVector(const StringPiece& full, const char* delim, vector<StringPiece>* vec,

                              bool omit_empty_strings);

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

// SplitStringUsing()

// SplitStringToHashsetUsing()

// SplitStringToSetUsing()

// SplitStringToMapUsing()

// SplitStringToHashmapUsing()

// Splits a string using one or more byte delimiters, presented as a

// nul-terminated c string. Append the components to 'result'. If there are

// consecutive delimiters, this function skips over all of them: in other words,

// empty components are dropped. If you want to keep empty components, try

// SplitStringAllowEmpty().

//

// NOTE: Do not use this for multi-byte delimiters such as UTF-8 strings. Use

// strings::Split() with strings::delimiter::Literal as the delimiter.

//

// ==> NEW API: Consider using the new Split API defined above. <==

// Example:

//

//   using strings::SkipEmpty;

//   using strings::Split;

//   using strings::delimiter::AnyOf;

//

//   vector<string> v = Split(full, AnyOf(delimiter), SkipEmpty());

//

// For even better performance, store the result in a vector<StringPiece>

// to avoid string copies.

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

void SplitStringUsing(const string& full, const char* delimiters, vector<string>* result);

void SplitStringToHashsetUsing(const string& full, const char* delimiters,

                               std::unordered_set<string>* result);

void SplitStringToSetUsing(const string& full, const char* delimiters, set<string>* result);

// The even-positioned (0-based) components become the keys for the

// odd-positioned components that follow them. When there is an odd

// number of components, the value for the last key will be unchanged

// if the key was already present in the hash table, or will be the

// empty string if the key is a newly inserted key.

void SplitStringToMapUsing(const string& full, const char* delim, map<string, string>* result);

void SplitStringToHashmapUsing(const string& full, const char* delim,

                               std::unordered_map<string, string>* result);

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

// SplitStringAllowEmpty()

//

// Split a string using one or more byte delimiters, presented as a

// nul-terminated c string. Append the components to 'result'. If there are

// consecutive delimiters, this function will return corresponding empty

// strings.  If you want to drop the empty strings, try SplitStringUsing().

//

// If "full" is the empty string, yields an empty string as the only value.

//

// ==> NEW API: Consider using the new Split API defined above. <==

//

//   using strings::Split;

//   using strings::delimiter::AnyOf;

//

//   vector<string> v = Split(full, AnyOf(delimiter));

//

// For even better performance, store the result in a vector<StringPiece> to

// avoid string copies.

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

void SplitStringAllowEmpty(const string& full, const char* delim, vector<string>* result);

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

// SplitStringWithEscaping()

// SplitStringWithEscapingAllowEmpty()

// SplitStringWithEscapingToSet()

// SplitStringWithEscapingToHashset()

//   Split the string using the specified delimiters, taking escaping into

//   account. '\' is not allowed as a delimiter.

//

//   Within the string, preserve a delimiter preceded by a backslash as a

//   literal delimiter. In addition, preserve two consecutive backslashes as

//   a single literal backslash. Do not unescape any other backslash-character

//   sequence.

//

//   Eg. 'foo\=bar=baz\\qu\ux' split on '=' becomes ('foo=bar', 'baz\qu\ux')

//

//   All versions other than "AllowEmpty" discard any empty substrings.

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

void SplitStringWithEscaping(const string& full, const strings::CharSet& delimiters,

                             vector<string>* result);

void SplitStringWithEscapingAllowEmpty(const string& full, const strings::CharSet& delimiters,

                                       vector<string>* result);

void SplitStringWithEscapingToSet(const string& full, const strings::CharSet& delimiters,

                                  set<string>* result);

void SplitStringWithEscapingToHashset(const string& full, const strings::CharSet& delimiters,

                                      std::unordered_set<string>* result);

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

// SplitStringIntoNPiecesAllowEmpty()

//    Split a string using a nul-terminated list of byte

//    delimiters. Append the components to 'result'.  If there are

//    consecutive delimiters, this function will return corresponding

//    empty strings. The string is split into at most the specified

//    number of pieces greedily. This means that the last piece may

//    possibly be split further. To split into as many pieces as

//    possible, specify 0 as the number of pieces.

//

//    If "full" is the empty string, yields an empty string as the only value.

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

void SplitStringIntoNPiecesAllowEmpty(const string& full, const char* delimiters, int pieces,

                                      vector<string>* result);

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

// SplitStringAndParse()

// SplitStringAndParseToContainer()

// SplitStringAndParseToList()

//    Split a string using a nul-terminated list of character

//    delimiters.  For each component, parse using the provided

//    parsing function and if successful, append it to 'result'.

//    Return true if and only if all components parse successfully.

//    If there are consecutive delimiters, this function skips over

//    all of them.  This function will correctly handle parsing

//    strings that have embedded \0s.

//

// SplitStringAndParse fills into a vector.

// SplitStringAndParseToContainer fills into any container that implements

//    a single-argument insert function. (i.e. insert(const value_type& x) ).

// SplitStringAndParseToList fills into any container that implements a single-

//    argument push_back function (i.e. push_back(const value_type& x) ), plus

//    value_type& back() and pop_back().

//    NOTE: This implementation relies on parsing in-place into the "back()"

//    reference, so its performance may depend on the efficiency of back().

//

// Example Usage:

//  vector<double> values;

//  CHECK(SplitStringAndParse("1.0,2.0,3.0", ",", &safe_strtod, &values));

//  CHECK_EQ(3, values.size());

//

//  vector<int64> values;

//  CHECK(SplitStringAndParse("1M,2M,3M", ",",

//        &HumanReadableNumBytes::ToInt64, &values));

//  CHECK_EQ(3, values.size());

//

//  set<int64> values;

//  CHECK(SplitStringAndParseToContainer("3,1,1,2", ",",

//        &safe_strto64, &values));

//  CHECK_EQ(4, values.size());

//

//  deque<int64> values;

//  CHECK(SplitStringAndParseToList("3,1,1,2", ",", &safe_strto64, &values));

//  CHECK_EQ(4, values.size());

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

template <class T>

bool SplitStringAndParse(StringPiece source, StringPiece delim,

                         bool (*parse)(const string& str, T* value), vector<T>* result);

template <class Container>

bool SplitStringAndParseToContainer(StringPiece source, StringPiece delim,

                                    bool (*parse)(const string& str,

                                                  typename Container::value_type* value),

                                    Container* result);

template <class List>

bool SplitStringAndParseToList(StringPiece source, StringPiece delim,

                               bool (*parse)(const string& str, typename List::value_type* value),

                               List* result);

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

// SplitRange()

//    Splits a string of the form "<from>-<to>".  Either or both can be

//    missing.  A raw number (<to>) is interpreted as "<to>-".  Modifies

//    parameters insofar as they're specified by the string.  RETURNS

//    true iff the input is a well-formed range.  If it RETURNS false,

//    from and to remain unchanged.  The range in rangestr should be

//    terminated either by "\0" or by whitespace.

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

bool SplitRange(const char* rangestr, int* from, int* to);

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

// SplitCSVLineWithDelimiter()

//    CSV lines come in many guises.  There's the Comma Separated Values

//    variety, in which fields are separated by (surprise!) commas.  There's

//    also the tab-separated values variant, in which tabs separate the

//    fields.  This routine handles both, which makes it almost like

//    SplitUsing(line, delimiter), but for some special processing.  For both

//    delimiters, whitespace is trimmed from either side of the field value.

//    If the delimiter is ',', we play additional games with quotes.  A

//    field value surrounded by double quotes is allowed to contain commas,

//    which are not treated as field separators.  Within a double-quoted

//    string, a series of two double quotes signals an escaped single double

//    quote.  It'll be clearer in the examples.

//    Example:

//     Google , x , "Buchheit, Paul", "string with "" quote in it"

//     -->  [Google], [x], [Buchheit, Paul], [string with " quote in it]

//

// SplitCSVLine()

//    A convenience wrapper around SplitCSVLineWithDelimiter which uses

//    ',' as the delimiter.

//

// The following variants of SplitCSVLine() are not recommended for new code.

// Please consider the CSV parser in //util/csv as an alternative.  Examples:

// To parse a single line:

//     #include "util/csv/parser.h"

//     vector<string> fields = util::csv::ParseLine(line).fields();

//

// To parse an entire file:

//     #include "util/csv/parser.h"

//     for (Record rec : Parser(source)) {

//       vector<string> fields = rec.fields();

//     }

//

// See //util/csv/parser.h for more complete documentation.

//

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

void SplitCSVLine(char* line, vector<char*>* cols);

void SplitCSVLineWithDelimiter(char* line, char delimiter, vector<char*>* cols);

// SplitCSVLine string wrapper that internally makes a copy of string line.

void SplitCSVLineWithDelimiterForStrings(const string& line, char delimiter, vector<string>* cols);

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

// SplitStructuredLine()

//    Splits a line using the given delimiter, and places the columns

//    into 'cols'. This is unlike 'SplitUsing(line, ",")' because you can

//    define pairs of opening closing symbols inside which the delimiter should

//    be ignored. If the symbol_pair string has an odd number of characters,

//    the last character (which cannot be paired) will be assumed to be both an

//    opening and closing symbol.

//    WARNING : The input string 'line' is destroyed in the process.

//    The function returns 0 if the line was parsed correctly (i.e all the

//    opened braces had their closing braces) otherwise, it returns the position

//    of the error.

//    Example:

//     SplitStructuredLine("item1,item2,{subitem1,subitem2},item4,[5,{6,7}]",

//                         ',',

//                         "{}[]", &output)

//     --> output = { "item1", "item2", "{subitem1,subitem2}", "item4",

//                    "[5,{6,7}]" }

//    Example2: trying to split "item1,[item2,{4,5],5}" will fail and the

//              function will return the position of the problem : ]

//

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

char* SplitStructuredLine(char* line, char delimiter, const char* symbol_pairs,

                          vector<char*>* cols);

// Similar to the function with the same name above, but splits a StringPiece

// into StringPiece parts. Returns true if successful.

bool SplitStructuredLine(StringPiece line, char delimiter, const char* symbol_pairs,

                         vector<StringPiece>* cols);

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

// SplitStructuredLineWithEscapes()

//    Like SplitStructuredLine but also allows characters to be escaped.

//

//    WARNING: the escape characters will be replicated in the output

//    columns rather than being consumed, i.e. if {} were the opening and

//    closing symbols, using \{ to quote a curly brace in the middle of

//    an option would pass this unchanged.

//

//    Example:

//     SplitStructuredLineWithEscapes(

//       "\{item1\},it\\em2,{\{subitem1\},sub\\item2},item4\,item5,[5,{6,7}]",

//                     ',',

//                     "{}[]",

//                     &output)

//     --> output = { "\{item1\}", "it\\em2", "{\{subitem1\},sub\\item2}",

//                    "item4\,item5", "[5,{6,7}]" }

//

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

char* SplitStructuredLineWithEscapes(char* line, char delimiter, const char* symbol_pairs,

                                     vector<char*>* cols);

// Similar to the function with the same name above, but splits a StringPiece

// into StringPiece parts. Returns true if successful.

bool SplitStructuredLineWithEscapes(StringPiece line, char delimiter, const char* symbol_pairs,

                                    vector<StringPiece>* cols);

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

// DEPRECATED(jgm): See the "NEW API" comment about this function below for

// example code showing an alternative.

//

// SplitStringIntoKeyValues()

// Split a line into a key string and a vector of value strings. The line has

// the following format:

//

// <key><kvsep>+<vvsep>*<value1><vvsep>+<value2><vvsep>+<value3>...<vvsep>*

//

// where key and value are strings; */+ means zero/one or more; <kvsep> is

// a delimiter character to separate key and value; and <vvsep> is a delimiter

// character to separate between values. The user can specify a bunch of

// delimiter characters using a string. For example, if the user specifies

// the separator string as "\t ", then either ' ' or '\t' or any combination

// of them wil be treated as separator. For <vvsep>, the user can specify a

// empty string to indicate there is only one value.

//

// Note: this function assumes the input string begins exactly with a

// key. Therefore, if you use whitespaces to separate key and value, you

// should not let whitespace precedes the key in the input. Otherwise, you

// will get an empty string as the key.

//

// A line with no <kvsep> will return an empty string as the key, even if

// <key> is non-empty!

//

// The syntax makes it impossible for a value to be the empty string.

// It is possible for the number of values to be zero.

//

// Returns false if the line has no <kvsep> or if the number of values is

// zero.

//

// ==> NEW API: Consider using the new Split API defined above. <==

//

// The SplitStringIntoKeyValues() function has some subtle and surprising

// semantics in various corner cases. To avoid this the strings::Split API is

// recommended. The following example shows how to split a string of delimited

// key-value pairs into a vector of pairs using the strings::Split API.

//

//   using strings::Split;

//   using strings::delimiter::AnyOf;

//   using strings::delimiter::Limit;

//

//   pair<string, StringPiece> key_values =

//       Split(line, Limit(AnyOf(kv_delim), 1));

//   string key = key_values.first;

//   vector<string> values = Split(key_values.second, AnyOf(vv_delim));

//

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

bool SplitStringIntoKeyValues(const string& line, const string& key_value_delimiters,

                              const string& value_value_delimiters, string* key,

                              vector<string>* values);

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

// SplitStringIntoKeyValuePairs()

// Split a line into a vector of <key, value> pairs. The line has

// the following format:

//

// <kvpsep>*<key1><kvsep>+<value1><kvpsep>+<key2><kvsep>+<value2>...<kvpsep>*

//

// Where key and value are strings; */+ means zero/one or more. <kvsep> is

// a delimiter character to separate key and value and <kvpsep> is a delimiter

// character to separate key value pairs. The user can specify a bunch of

// delimiter characters using a string.

//

// Note: this function assumes each key-value pair begins exactly with a

// key. Therefore, if you use whitespaces to separate key and value, you

// should not let whitespace precede the key in the pair. Otherwise, you

// will get an empty string as the key.

//

// A pair with no <kvsep> will return empty strings as the key and value,

// even if <key> is non-empty!

//

// Returns false for pairs with no <kvsep> specified and for pairs with

// empty strings as values.

//

// ==> NEW API: Consider using the new Split API defined above. <==

//

// The SplitStringIntoKeyValuePairs() function has some subtle and surprising

// semantics in various corner cases. To avoid this the strings::Split API is

// recommended. The following example shows how to split a string of delimited

// key-value pairs into a vector of pairs using the strings::Split API.

//

//   using strings::SkipEmpty;

//   using strings::Split;

//   using strings::delimiter::AnyOf;

//   using strings::delimiter::Limit;

//

//   vector<pair<string, string>> pairs;  // or even map<string, string>

//   for (StringPiece sp : Split(line, AnyOf(pair_delim), SkipEmpty())) {

//     pairs.push_back(Split(sp, Limit(AnyOf(kv_delim), 1), SkipEmpty()));

//   }

//

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

bool SplitStringIntoKeyValuePairs(const string& line, const string& key_value_delimiters,

                                  const string& key_value_pair_delimiters,

                                  vector<pair<string, string>>* kv_pairs);

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

// SplitLeadingDec32Values()

// SplitLeadingDec64Values()

//    A simple parser for space-separated decimal int32/int64 values.

//    Appends parsed integers to the end of the result vector, stopping

//    at the first unparsable spot.  Skips past leading and repeated

//    whitespace (does not consume trailing whitespace), and returns

//    a pointer beyond the last character parsed.

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

const char* SplitLeadingDec32Values(const char* next, vector<int32>* result);

const char* SplitLeadingDec64Values(const char* next, vector<int64>* result);

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

// SplitOneIntToken()

// SplitOneInt32Token()

// SplitOneUint32Token()

// SplitOneInt64Token()

// SplitOneUint64Token()

// SplitOneDoubleToken()

// SplitOneFloatToken()

//   Parse a single "delim" delimited number from "*source" into "*value".

//   Modify *source to point after the delimiter.

//   If no delimiter is present after the number, set *source to NULL.

//

//   If the start of *source is not an number, return false.

//   If the int is followed by the null character, return true.

//   If the int is not followed by a character from delim, return false.

//   If *source is NULL, return false.

//

//   They cannot handle decimal numbers with leading 0s, since they will be

//   treated as octal.

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

bool SplitOneIntToken(const char** source, const char* delim, int* value);

bool SplitOneInt32Token(const char** source, const char* delim, int32* value);

bool SplitOneUint32Token(const char** source, const char* delim, uint32* value);

bool SplitOneInt64Token(const char** source, const char* delim, int64* value);

bool SplitOneUint64Token(const char** source, const char* delim, uint64* value);

bool SplitOneDoubleToken(const char** source, const char* delim, double* value);

bool SplitOneFloatToken(const char** source, const char* delim, float* value);

// Some aliases, so that the function names are standardized against the names

// of the reflection setters/getters in proto2. This makes it easier to use

// certain macros with reflection when creating custom text formats for protos.

inline bool SplitOneUInt32Token(const char** source, const char* delim, uint32* value) {

    return SplitOneUint32Token(source, delim, value);

}

inline bool SplitOneUInt64Token(const char** source, const char* delim, uint64* value) {

    return SplitOneUint64Token(source, delim, value);

}

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

// SplitOneDecimalIntToken()

// SplitOneDecimalInt32Token()

// SplitOneDecimalUint32Token()

// SplitOneDecimalInt64Token()

// SplitOneDecimalUint64Token()

// Parse a single "delim"-delimited number from "*source" into "*value".

// Unlike SplitOneIntToken, etc., this function always interprets

// the numbers as decimal.

bool SplitOneDecimalIntToken(const char** source, const char* delim, int* value);

bool SplitOneDecimalInt32Token(const char** source, const char* delim, int32* value);

bool SplitOneDecimalUint32Token(const char** source, const char* delim, uint32* value);

bool SplitOneDecimalInt64Token(const char** source, const char* delim, int64* value);

bool SplitOneDecimalUint64Token(const char** source, const char* delim, uint64* value);

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

// SplitOneHexUint32Token()

// SplitOneHexUint64Token()

// Once more, for hexadecimal numbers (unsigned only).

bool SplitOneHexUint32Token(const char** source, const char* delim, uint32* value);

bool SplitOneHexUint64Token(const char** source, const char* delim, uint64* value);

// ###################### TEMPLATE INSTANTIATIONS BELOW #######################

// SplitStringAndParse() -- see description above

template <class T>

bool SplitStringAndParse(StringPiece source, StringPiece delim,

                         bool (*parse)(const string& str, T* value), vector<T>* result) {

    return SplitStringAndParseToList(source, delim, parse, result);

}

namespace strings {

namespace internal {

template <class Container, class InsertPolicy>

bool SplitStringAndParseToInserter(StringPiece source, StringPiece delim,

                                   bool (*parse)(const string& str,

                                                 typename Container::value_type* value),

                                   Container* result, InsertPolicy insert_policy) {

    CHECK(NULL != parse);

    CHECK(NULL != result);

    CHECK(NULL != delim.data());

    CHECK_GT(delim.size(), 0);

    bool retval = true;

    vector<StringPiece> pieces =

            strings::Split(source, strings::delimiter::AnyOf(delim), strings::SkipEmpty());

    for (const auto& piece : pieces) {

        typename Container::value_type t;

        if (parse(piece.as_string(), &t)) {