--
-- Created by: Cyril.
-- Created at: 15/6/20 下午2:38
-- Email: houshoushuai@gmail.com
--

local strsub = string.sub
local t_insert = table.insert
local t_concat = table.concat

local function get_from_string ( s , i )
    i = i or 1
    return function ( n )
        if not n then -- Rest of string
        n = #s - i + 1
        end
        i = i + n
        assert ( i-1 <= #s , "Unable to read enough characters" )
        return strsub ( s , i-n , i-1 )
    end , function ( new_i )
        if new_i then i = new_i end
        return i
    end
end

local function string_to_array_of_chars ( s )
    local t = { }
    for i = 1 , #s do
        t [ i ] = strsub ( s , i , i )
    end
    return t
end

local function read_terminated_string ( get , terminators )
    local terminators = string_to_array_of_chars ( terminators or "\0" )
    local str = { }
    local found = 0
    while found < #terminators do
        local c = get ( 1 )
        if c == terminators [ found + 1 ] then
            found = found + 1
        else
            found = 0
        end
        t_insert ( str , c )
    end
    return t_concat ( str , "" , 1 , #str - #terminators )
end

return {
    get_from_string = get_from_string ;
    read_terminated_string = read_terminated_string ;
}