apisix/core/string.lua

--
-- Licensed to the Apache Software Foundation (ASF) under one or more
-- contributor license agreements.  See the NOTICE file distributed with
-- this work for additional information regarding copyright ownership.
-- The ASF licenses this file to You 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.
--
local error = error
local type = type
local str_find = string.find
local ffi         = require("ffi")
local C           = ffi.C
local ffi_cast    = ffi.cast


ffi.cdef[[
    int memcmp(const void *s1, const void *s2, size_t n);
]]


local _M = {
    version = 0.1,
}


setmetatable(_M, {__index = string})


-- find a needle from a haystack in the plain text way
-- note: Make sure that the haystack is 'string' type, otherwise an exception will be thrown.
function _M.find(haystack, needle, from)
    return str_find(haystack, needle, from or 1, true)
end


function _M.has_prefix(s, prefix)
    if type(s) ~= "string" or type(prefix) ~= "string" then
        error("unexpected type: s:" .. type(s) .. ", prefix:" .. type(prefix))
    end
    if #s < #prefix then
        return false
    end
    local rc = C.memcmp(s, prefix, #prefix)
    return rc == 0
end


function _M.has_suffix(s, suffix)
    if type(s) ~= "string" or type(suffix) ~= "string" then
        error("unexpected type: s:" .. type(s) .. ", suffix:" .. type(suffix))
    end
    if #s < #suffix then
        return false
    end
    local rc = C.memcmp(ffi_cast("char *", s) + #s - #suffix, suffix, #suffix)
    return rc == 0
end


return _M