spanparsing.h

// Copyright (c) 2018-2019 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_UTIL_SPANPARSING_H
#define BITCOIN_UTIL_SPANPARSING_H

#include <span.h>

#include <string>
#include <string_view>
#include <vector>

namespace spanparsing {

/** Parse a constant.
 *
 * If sp's initial part matches str, sp is updated to skip that part, and true is returned.
 * Otherwise sp is unmodified and false is returned.
 */
bool Const(const std::string& str, Span<const char>& sp);

/** Parse a function call.
 *
 * If sp's initial part matches str + "(", and sp ends with ")", sp is updated to be the
 * section between the braces, and true is returned. Otherwise sp is unmodified and false
 * is returned.
 */
bool Func(const std::string& str, Span<const char>& sp);

/** Extract the expression that sp begins with.
 *
 * This function will return the initial part of sp, up to (but not including) the first
 * comma or closing brace, skipping ones that are surrounded by braces. So for example,
 * for "foo(bar(1),2),3" the initial part "foo(bar(1),2)" will be returned. sp will be
 * updated to skip the initial part that is returned.
 */
Span<const char> Expr(Span<const char>& sp);

/** Split a string on any char found in separators, returning a vector.
 *
 * If sep does not occur in sp, a singleton with the entirety of sp is returned.
 *
 * Note that this function does not care about braces, so splitting
 * "foo(bar(1),2),3) on ',' will return {"foo(bar(1)", "2)", "3)"}.
 */
template <typename T = Span<const char>>
std::vector<T> Split(const Span<const char>& sp, std::string_view separators)
{
    std::vector<T> ret;
    auto it = sp.begin();
    auto start = it;
    while (it != sp.end()) {
        if (separators.find(*it) != std::string::npos) {
            ret.emplace_back(start, it);
            start = it + 1;
        }
        ++it;
    }
    ret.emplace_back(start, it);
    return ret;
}

/** Split a string on every instance of sep, returning a vector.
 *
 * If sep does not occur in sp, a singleton with the entirety of sp is returned.
 *
 * Note that this function does not care about braces, so splitting
 * "foo(bar(1),2),3) on ',' will return {"foo(bar(1)", "2)", "3)"}.
 */
template <typename T = Span<const char>>
std::vector<T> Split(const Span<const char>& sp, char sep)
{
    return Split<T>(sp, std::string_view{&sep, 1});
}

} // namespace spanparsing

#endif // BITCOIN_UTIL_SPANPARSING_H