init commit

plugins/string.lua

@@ -0,0 +1,68 @@
+--
+-- 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
+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