Util.cpp

Go to the documentation of this file.

 
 
#include "Util.hpp"
 
#include <algorithm>
#include <cctype>
#include <charconv>
 
namespace tinysql {
 
namespace {
 
bool isSpace(char c) { return c == ' ' || c == '\t' || c == '\r' || c == '\n'; }
 
char upper(unsigned char c) { return static_cast<char>(std::toupper(c)); }
 
}  // namespace
 
std::string_view trimRight(std::string_view text)
{
    while (!text.empty() && isSpace(text.back())) {
        text.remove_suffix(1);
    }
    return text;
}
 
std::string_view trim(std::string_view text)
{
    while (!text.empty() && isSpace(text.front())) {
        text.remove_prefix(1);
    }
    return trimRight(text);
}
 
std::string toUpper(std::string_view text)
{
    std::string result(text);
    std::ranges::transform(result, result.begin(), [](unsigned char c) { return upper(c); });
    return result;
}
 
bool equalsIgnoreCase(std::string_view a, std::string_view b)
{
    return std::ranges::equal(a, b, [](unsigned char x, unsigned char y) { return upper(x) == upper(y); });
}
 
bool matchesLike(std::string_view text, std::string_view pattern)
{
    constexpr std::size_t kNone = std::string_view::npos;
    std::size_t t = 0, p = 0;
    // Where the last `%` was, and where in the text it started matching: on a mismatch we come
    // back there and let that `%` swallow one more character.
    std::size_t lastPercent = kNone, resumeText = 0;
 
    while (t < text.size()) {
        if (p < pattern.size() && pattern[p] == '%') {
            lastPercent = p++;
            resumeText = t;
        } else if (p < pattern.size() && (pattern[p] == '_' || upper(pattern[p]) == upper(text[t]))) {
            ++p;
            ++t;
        } else if (lastPercent != kNone) {
            p = lastPercent + 1;
            t = ++resumeText;
        } else {
            return false;
        }
    }
    while (p < pattern.size() && pattern[p] == '%') {
        ++p;  // a trailing `%` also matches the empty rest
    }
    return p == pattern.size();
}
 
std::optional<long long> parseInteger(std::string_view text)
{
    text = trim(text);
    if (text.starts_with('+')) {
        text.remove_prefix(1);
    }
    if (text.empty()) {
        return std::nullopt;
    }
    long long value = 0;
    const char* end = text.data() + text.size();
    auto [ptr, ec] = std::from_chars(text.data(), end, value);
    if (ec != std::errc{} || ptr != end) {
        return std::nullopt;
    }
    return value;
}
 
}  // namespace tinysql