stringref.h

/*
Copyright 2013-present Barefoot Networks, Inc.
 
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.
*/
 
#ifndef LIB_STRINGREF_H_
#define LIB_STRINGREF_H_
 
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <string>
 
#include "config.h"
#include "cstring.h"
 
#if !HAVE_MEMRCHR
static inline void *memrchr(const char *s, int c, size_t n) {
    for (auto *p = s + n - 1; p >= s; --p)
        if (*p == c) return const_cast<char *>(p);
    return nullptr;
}
#endif
 
/* A StringRef is a *TEMPORARY* reference to a string held in memory managed by some other
 * object.  As such, it becomes dangling (invalid) when that other object goes away, so needs
 * to be used with care.  StringRefs should in general have short lifetimes, and not be
 * stored in other long-lived objects. */
 
struct [[deprecated("Use std::string_view instead")]] StringRef {
    const char *p;
    size_t len;
    StringRef() : p(0), len(0) {}
    StringRef(const char *str, size_t l) : p(str), len(l) {}
    StringRef(const char *str) : p(str), len(str ? strlen(str) : 0) {}     // NOLINT
    StringRef(const std::string &str) : p(str.data()), len(str.size()) {}  // NOLINT
    StringRef(cstring str) : p(str.c_str()), len(str.size()) {}            // NOLINT
    void clear() {
        p = 0;
        len = 0;
    }
    StringRef(const StringRef &a) : p(a.p), len(a.len) {}
    // avoid clang-tidy complaining about assignment that is actually safe
    // NOLINTBEGIN(bugprone-unhandled-self-assignment)
    StringRef &operator=(const StringRef &a) {
        p = a.p;
        len = a.len;
        return *this;
    }
    // NOLINTEND(bugprone-unhandled-self-assignment)
    explicit operator bool() const { return p != 0; }
 
    bool operator==(const StringRef &a) const {
        return p ? (a.p && len == a.len && (!len || !memcmp(p, a.p, len))) : !a.p;
    }
    bool operator!=(const StringRef &a) const { return !operator==(a); }
    bool operator==(const std::string &a) const { return operator==(StringRef(a)); }
    bool operator==(const char *a) const {
        return p ? (a && (!len || !strncmp(p, a, len)) && !a[len]) : !a;
    }
    bool operator==(cstring a) const { return operator==(a.c_str()); }
    template <class T>
    bool operator!=(T a) const {
        return !(*this == a);
    }
    bool isNullOrEmpty() const { return p == 0 || len == 0; }
 
    int compare(const StringRef &a) const {
        if (!p) return a.p ? -1 : 0;
        if (!a.p) return 1;
        int rv = memcmp(p, a.p, std::min(len, a.len));
        if (!rv && len != a.len) rv = len < a.len ? -1 : 1;
        return rv;
    }
    int compare(const std::string &a) const { return compare(StringRef(a)); }
    int compare(const char *a) const {
        if (!p) return a ? -1 : 0;
        if (!a) return 1;
        int rv = strncmp(p, a, len);
        if (!rv && a[len]) rv = -1;
        return rv;
    }
    int compare(cstring a) const { return compare(a.c_str()); }
    template <class T>
    bool operator<(T a) const {
        return compare(a) < 0;
    }
    template <class T>
    bool operator<=(T a) const {
        return compare(a) <= 0;
    }
    template <class T>
    bool operator>(T a) const {
        return compare(a) > 0;
    }
    template <class T>
    bool operator>=(T a) const {
        return compare(a) >= 0;
    }
 
    explicit operator std::string() const { return std::string(p, len); }
    operator cstring() const { return std::string(p, len); }
    cstring toString() const { return std::string(p, len); }
    std::string string() const { return std::string(p, len); }
    StringRef &operator+=(size_t i) {
        if (len < i) {
            p = 0;
            len = 0;
        } else {
            p += i;
            len -= i;
        }
        return *this;
    }
    StringRef &operator++() {
        p++;
        if (len)
            len--;
        else
            p = 0;
        return *this;
    }  // NOLINT
    StringRef operator++(int) {
        StringRef rv(*this);
        ++*this;
        return rv;
    }
    StringRef &operator--() {
        if (len)
            len--;
        else
            p = 0;
        return *this;
    }  // NOLINT
    StringRef operator--(int) {
        StringRef rv(*this);
        --*this;
        return rv;
    }
    char operator[](size_t i) const { return i < len ? p[i] : 0; }
    char operator*() const { return len ? *p : 0; }
    StringRef operator+(size_t i) const {
        StringRef rv(*this);
        rv += i;
        return rv;
    }
    StringRef &trim(const char *white = " \t\r\n") {
        while (len > 0 && strchr(white, *p)) {
            p++;
            len--;
        }
        while (len > 0 && strchr(white, p[len - 1])) {
            len--;
        }
        return *this;
    }
    bool trimCR() {
        bool rv = false;
        while (len > 0 && p[len - 1] == '\r') {
            rv = true;
            len--;
        }
        return rv;
    }
    StringRef trim(const char *white = " \t\r\n") const {
        StringRef rv(*this);
        rv.trim(white);
        return rv;
    }
    const char *begin() const { return p; }
    const char *end() const { return p + len; }
    const char *find(char ch) const {
        return p ? static_cast<const char *>(memchr(p, ch, len)) : p;
    }
    const char *findlast(char ch) const {
        return p ? static_cast<const char *>(memrchr(p, ch, len)) : p;
    }
    const char *find(const char *set) const {
        if (!p) return 0;
        size_t off = strcspn(p, set);
        return off >= len ? 0 : p + off;
    }
    const char *findstr(StringRef sub) {
        if (sub.len < 1) return p;
        const char *s = begin(), *e = end();
        while (s < e && (s = static_cast<const char *>(memchr(s, *sub.p, e - s)))) {
            if (sub.len > (size_t)(e - s)) return nullptr;
            if (!memcmp(s, sub.p, sub.len)) return s;
            s++;
        }
        return nullptr;
    }
    StringRef before(const char *s) const {
        return (size_t)(s - p) <= len ? StringRef(p, s - p) : StringRef();
    }
    StringRef after(const char *s) const {
        return (size_t)(s - p) <= len ? StringRef(s, p + len - s) : StringRef();
    }
    StringRef substr(size_t start, size_t length) const {
        if (len <= start) return 0;
        if (len <= length) return StringRef(p + start, len - start);
        return StringRef(p + start, length);
    }
    class Split;
    Split split(char) const;
    Split split(const char *) const;
};
 
template <class T>
inline auto operator==(T a, const StringRef &b) -> decltype(b.operator==(a)) {
    return b == a;
}
template <class T>
inline auto operator!=(T a, const StringRef &b) -> decltype(b.operator!=(a)) {
    return b != a;
}
template <class T>
inline auto operator>=(T a, const StringRef &b) -> decltype(b.operator<=(a)) {
    return b <= a;
}
template <class T>
inline auto operator>(T a, const StringRef &b) -> decltype(b.operator<(a)) {
    return b < a;
}
template <class T>
inline auto operator<=(T a, const StringRef &b) -> decltype(b.operator>=(a)) {
    return b >= a;
}
template <class T>
inline auto operator<(T a, const StringRef &b) -> decltype(b.operator>(a)) {
    return b > a;
}
 
inline std::ostream &operator<<(std::ostream &os, const StringRef &a) {
    return a.len ? os.write(a.p, a.len) : os;
}
inline std::string &operator+=(std::string &s, const StringRef &a) {
    return a.len ? s.append(a.p, a.len) : s;
}
inline std::string operator+(const StringRef &s, const StringRef &a) {
    std::string rv(s);
    rv += a;
    return rv;
}
inline std::string operator+(const std::string &s, const StringRef &a) {
    std::string rv(s);
    rv += a;
    return rv;
}
inline std::string operator+(const StringRef &s, const std::string &a) {
    std::string rv(s);
    rv += a;
    return rv;
}
inline std::string operator+(const char *s, const StringRef &a) {
    std::string rv(s);
    rv += a;
    return rv;
}
inline std::string operator+(const StringRef &s, const char *a) {
    std::string rv(s);
    rv += a;
    return rv;
}
inline std::string operator+(cstring s, const StringRef &a) {
    std::string rv(s);
    rv += a;
    return rv;
}
inline std::string operator+(const StringRef &s, cstring a) {
    std::string rv(s);
    rv += a;
    return rv;
}
 
class StringRef::Split {
    StringRef rest;
    const char *set;
    const char *ptr;
    friend struct StringRef;
    Split(StringRef r, const char *s, const char *p) : rest(r), set(s), ptr(p) {}
 
 public:
    Split begin() const { return *this; }
    Split end() const { return Split(StringRef(), nullptr, nullptr); }
    StringRef operator*() const { return ptr ? rest.before(ptr) : rest; }
    Split &operator++() {
        if (ptr) {
            rest = rest.after(ptr + 1);
            ptr = set ? rest.find(set) : rest.find(*ptr);
        } else {
            rest.clear();
        }
        return *this;
    }
    bool operator==(const Split &a) const { return rest == a.rest && ptr == a.ptr; }
    bool operator!=(const Split &a) const { return rest != a.rest || ptr != a.ptr; }
};
 
inline StringRef::Split StringRef::split(char ch) const { return Split(*this, nullptr, find(ch)); }
inline StringRef::Split StringRef::split(const char *s) const { return Split(*this, s, find(s)); }
 
#endif /* LIB_STRINGREF_H_ */