//===--- StringRef.h - Constant String Reference Wrapper --------*- C++ -*-===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// #ifndef LLVM_ADT_STRINGREF_H #define LLVM_ADT_STRINGREF_H #include <cassert> #include <cstring> #include <utility> #include <string> namespace llvm { template<typename T> class SmallVectorImpl; class APInt; /// StringRef - Represent a constant reference to a string, i.e. a character /// array and a length, which need not be null terminated. /// /// This class does not own the string data, it is expected to be used in /// situations where the character data resides in some other buffer, whose /// lifetime extends past that of the StringRef. For this reason, it is not in /// general safe to store a StringRef. class StringRef { public: typedef const char *iterator; typedef const char *const_iterator; static const size_t npos = ~size_t(0); typedef size_t size_type; private: /// The start of the string, in an external buffer. const char *Data; /// The length of the string. size_t Length; // Workaround PR5482: nearly all gcc 4.x miscompile StringRef and std::min() // Changing the arg of min to be an integer, instead of a reference to an // integer works around this bug. size_t min(size_t a, size_t b) const { return a < b ? a : b; } size_t max(size_t a, size_t b) const { return a > b ? a : b; } public: /// @name Constructors /// @{ /// Construct an empty string ref. /*implicit*/ StringRef() : Data(0), Length(0) {} /// Construct a string ref from a cstring. /*implicit*/ StringRef(const char *Str) : Data(Str), Length(::strlen(Str)) {} /// Construct a string ref from a pointer and length. /*implicit*/ StringRef(const char *data, size_t length) : Data(data), Length(length) {} /// Construct a string ref from an std::string. /*implicit*/ StringRef(const std::string &Str) : Data(Str.data()), Length(Str.length()) {} /// @} /// @name Iterators /// @{ iterator begin() const { return Data; } iterator end() const { return Data + Length; } /// @} /// @name String Operations /// @{ /// data - Get a pointer to the start of the string (which may not be null /// terminated). const char *data() const { return Data; } /// empty - Check if the string is empty. bool empty() const { return Length == 0; } /// size - Get the string size. size_t size() const { return Length; } /// front - Get the first character in the string. char front() const { assert(!empty()); return Data[0]; } /// back - Get the last character in the string. char back() const { assert(!empty()); return Data[Length-1]; } /// equals - Check for string equality, this is more efficient than /// compare() when the relative ordering of inequal strings isn't needed. bool equals(StringRef RHS) const { return (Length == RHS.Length && memcmp(Data, RHS.Data, RHS.Length) == 0); } /// equals_lower - Check for string equality, ignoring case. bool equals_lower(StringRef RHS) const { return Length == RHS.Length && compare_lower(RHS) == 0; } /// compare - Compare two strings; the result is -1, 0, or 1 if this string /// is lexicographically less than, equal to, or greater than the \arg RHS. int compare(StringRef RHS) const { // Check the prefix for a mismatch. if (int Res = memcmp(Data, RHS.Data, min(Length, RHS.Length))) return Res < 0 ? -1 : 1; // Otherwise the prefixes match, so we only need to check the lengths. if (Length == RHS.Length) return 0; return Length < RHS.Length ? -1 : 1; } /// compare_lower - Compare two strings, ignoring case. int compare_lower(StringRef RHS) const; /// \brief Determine the edit distance between this string and another /// string. /// /// \param Other the string to compare this string against. /// /// \param AllowReplacements whether to allow character /// replacements (change one character into another) as a single /// operation, rather than as two operations (an insertion and a /// removal). /// /// \returns the minimum number of character insertions, removals, /// or (if \p AllowReplacements is \c true) replacements needed to /// transform one of the given strings into the other. If zero, /// the strings are identical. unsigned edit_distance(StringRef Other, bool AllowReplacements = true); /// str - Get the contents as an std::string. std::string str() const { return std::string(Data, Length); } /// @} /// @name Operator Overloads /// @{ char operator[](size_t Index) const { assert(Index < Length && "Invalid index!"); return Data[Index]; } /// @} /// @name Type Conversions /// @{ operator std::string() const { return str(); } /// @} /// @name String Predicates /// @{ /// startswith - Check if this string starts with the given \arg Prefix. bool startswith(StringRef Prefix) const { return Length >= Prefix.Length && memcmp(Data, Prefix.Data, Prefix.Length) == 0; } /// endswith - Check if this string ends with the given \arg Suffix. bool endswith(StringRef Suffix) const { return Length >= Suffix.Length && memcmp(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0; } /// @} /// @name String Searching /// @{ /// find - Search for the first character \arg C in the string. /// /// \return - The index of the first occurrence of \arg C, or npos if not /// found. size_t find(char C, size_t From = 0) const { for (size_t i = min(From, Length), e = Length; i != e; ++i) if (Data[i] == C) return i; return npos; } /// find - Search for the first string \arg Str in the string. /// /// \return - The index of the first occurrence of \arg Str, or npos if not /// found. size_t find(StringRef Str, size_t From = 0) const; /// rfind - Search for the last character \arg C in the string. /// /// \return - The index of the last occurrence of \arg C, or npos if not /// found. size_t rfind(char C, size_t From = npos) const { From = min(From, Length); size_t i = From; while (i != 0) { --i; if (Data[i] == C) return i; } return npos; } /// rfind - Search for the last string \arg Str in the string. /// /// \return - The index of the last occurrence of \arg Str, or npos if not /// found. size_t rfind(StringRef Str) const; /// find_first_of - Find the first character in the string that is \arg C, /// or npos if not found. Same as find. size_type find_first_of(char C, size_t = 0) const { return find(C); } /// find_first_of - Find the first character in the string that is in \arg /// Chars, or npos if not found. /// /// Note: O(size() * Chars.size()) size_type find_first_of(StringRef Chars, size_t From = 0) const; /// find_first_not_of - Find the first character in the string that is not /// \arg C or npos if not found. size_type find_first_not_of(char C, size_t From = 0) const; /// find_first_not_of - Find the first character in the string that is not /// in the string \arg Chars, or npos if not found. /// /// Note: O(size() * Chars.size()) size_type find_first_not_of(StringRef Chars, size_t From = 0) const; /// @} /// @name Helpful Algorithms /// @{ /// count - Return the number of occurrences of \arg C in the string. size_t count(char C) const { size_t Count = 0; for (size_t i = 0, e = Length; i != e; ++i) if (Data[i] == C) ++Count; return Count; } /// count - Return the number of non-overlapped occurrences of \arg Str in /// the string. size_t count(StringRef Str) const; /// getAsInteger - Parse the current string as an integer of the specified /// radix. If Radix is specified as zero, this does radix autosensing using /// extended C rules: 0 is octal, 0x is hex, 0b is binary. /// /// If the string is invalid or if only a subset of the string is valid, /// this returns true to signify the error. The string is considered /// erroneous if empty. /// bool getAsInteger(unsigned Radix, long long &Result) const; bool getAsInteger(unsigned Radix, unsigned long long &Result) const; bool getAsInteger(unsigned Radix, int &Result) const; bool getAsInteger(unsigned Radix, unsigned &Result) const; // TODO: Provide overloads for int/unsigned that check for overflow. /// getAsInteger - Parse the current string as an integer of the /// specified radix, or of an autosensed radix if the radix given /// is 0. The current value in Result is discarded, and the /// storage is changed to be wide enough to store the parsed /// integer. /// /// Returns true if the string does not solely consist of a valid /// non-empty number in the appropriate base. /// /// APInt::fromString is superficially similar but assumes the /// string is well-formed in the given radix. bool getAsInteger(unsigned Radix, APInt &Result) const; /// @} /// @name Substring Operations /// @{ /// substr - Return a reference to the substring from [Start, Start + N). /// /// \param Start - The index of the starting character in the substring; if /// the index is npos or greater than the length of the string then the /// empty substring will be returned. /// /// \param N - The number of characters to included in the substring. If N /// exceeds the number of characters remaining in the string, the string /// suffix (starting with \arg Start) will be returned. StringRef substr(size_t Start, size_t N = npos) const { Start = min(Start, Length); return StringRef(Data + Start, min(N, Length - Start)); } /// slice - Return a reference to the substring from [Start, End). /// /// \param Start - The index of the starting character in the substring; if /// the index is npos or greater than the length of the string then the /// empty substring will be returned. /// /// \param End - The index following the last character to include in the /// substring. If this is npos, or less than \arg Start, or exceeds the /// number of characters remaining in the string, the string suffix /// (starting with \arg Start) will be returned. StringRef slice(size_t Start, size_t End) const { Start = min(Start, Length); End = min(max(Start, End), Length); return StringRef(Data + Start, End - Start); } /// split - Split into two substrings around the first occurrence of a /// separator character. /// /// If \arg Separator is in the string, then the result is a pair (LHS, RHS) /// such that (*this == LHS + Separator + RHS) is true and RHS is /// maximal. If \arg Separator is not in the string, then the result is a /// pair (LHS, RHS) where (*this == LHS) and (RHS == ""). /// /// \param Separator - The character to split on. /// \return - The split substrings. std::pair<StringRef, StringRef> split(char Separator) const { size_t Idx = find(Separator); if (Idx == npos) return std::make_pair(*this, StringRef()); return std::make_pair(slice(0, Idx), slice(Idx+1, npos)); } /// split - Split into two substrings around the first occurrence of a /// separator string. /// /// If \arg Separator is in the string, then the result is a pair (LHS, RHS) /// such that (*this == LHS + Separator + RHS) is true and RHS is /// maximal. If \arg Separator is not in the string, then the result is a /// pair (LHS, RHS) where (*this == LHS) and (RHS == ""). /// /// \param Separator - The string to split on. /// \return - The split substrings. std::pair<StringRef, StringRef> split(StringRef Separator) const { size_t Idx = find(Separator); if (Idx == npos) return std::make_pair(*this, StringRef()); return std::make_pair(slice(0, Idx), slice(Idx + Separator.size(), npos)); } /// split - Split into substrings around the occurrences of a separator /// string. /// /// Each substring is stored in \arg A. If \arg MaxSplit is >= 0, at most /// \arg MaxSplit splits are done and consequently <= \arg MaxSplit /// elements are added to A. /// If \arg KeepEmpty is false, empty strings are not added to \arg A. They /// still count when considering \arg MaxSplit /// An useful invariant is that /// Separator.join(A) == *this if MaxSplit == -1 and KeepEmpty == true /// /// \param A - Where to put the substrings. /// \param Separator - The string to split on. /// \param MaxSplit - The maximum number of times the string is split. /// \param KeepEmpty - True if empty substring should be added. void split(SmallVectorImpl<StringRef> &A, StringRef Separator, int MaxSplit = -1, bool KeepEmpty = true) const; /// rsplit - Split into two substrings around the last occurrence of a /// separator character. /// /// If \arg Separator is in the string, then the result is a pair (LHS, RHS) /// such that (*this == LHS + Separator + RHS) is true and RHS is /// minimal. If \arg Separator is not in the string, then the result is a /// pair (LHS, RHS) where (*this == LHS) and (RHS == ""). /// /// \param Separator - The character to split on. /// \return - The split substrings. std::pair<StringRef, StringRef> rsplit(char Separator) const { size_t Idx = rfind(Separator); if (Idx == npos) return std::make_pair(*this, StringRef()); return std::make_pair(slice(0, Idx), slice(Idx+1, npos)); } /// @} }; /// @name StringRef Comparison Operators /// @{ inline bool operator==(StringRef LHS, StringRef RHS) { return LHS.equals(RHS); } inline bool operator!=(StringRef LHS, StringRef RHS) { return !(LHS == RHS); } inline bool operator<(StringRef LHS, StringRef RHS) { return LHS.compare(RHS) == -1; } inline bool operator<=(StringRef LHS, StringRef RHS) { return LHS.compare(RHS) != 1; } inline bool operator>(StringRef LHS, StringRef RHS) { return LHS.compare(RHS) == 1; } inline bool operator>=(StringRef LHS, StringRef RHS) { return LHS.compare(RHS) != -1; } /// @} } #endif