【Lua实战】字符串分割：手写 split 的边界处理

local function split(str, sep)
    if sep == nil then sep = "," end
    local result = {}
    local pattern = "([^" .. sep .. "]*)"
    local pos = 1
    while pos <= #str do
        local field = string.match(str, pattern, pos)
        table.insert(result, field)
        pos = pos + #field + 1
        if pos > #str and string.sub(str, -1) == sep then
            table.insert(result, "")
        end
    end
    return result
end

local function splitEx(str, sep)
    local result = {}
    local field = ""
    local i = 1
    while i <= #str do
        local matched = string.sub(str, i, i + #sep - 1) == sep
        if matched and not isEscaped(str, i) then
            table.insert(result, field)
            field = ""
            i = i + #sep
        else
            field = field .. string.sub(str, i, i)
            i = i + 1
        end
    end
    table.insert(result, field)
    return result
end