【原创】OpenResty Lua 中使用 Nginx 正则表达式

huijial

Lua 自带的正则表达式确实有点另类,不支持 “|” 而且正则语法不好适应，想用Nginx原生的正则表达式就需要在Lua中借助Nginx内置对象 ngx.re

　　正则在 nginx.conf 文件中错误的使用方法：

    # nginx.conf
 ? location /test {
 ?     content_by_lua '
 ?         local regex = "\d+"  -- THIS IS WRONG!!
 ?         local m = ngx.re.match("hello, 1234", regex)
 ?         if m then ngx.say(m[0]) else ngx.say("not matched!") end
 ?     ';
 ? }
# evaluates to "not matched!"



　　nginx.conf 文件中正确使用方法 记得是\\\\才能转义

    # nginx.conf
location /test {
content_by_lua '
local regex = "\\\\d+"
local m = ngx.re.match("hello, 1234", regex)
if m then ngx.say(m[0]) else ngx.say("not matched!") end
';
}
# evaluates to "1234"



　　可以使用Lua中特有的 [[ 正则 ]] 定义符号

    # nginx.conf
location /test {
content_by_lua '
local regex = [[\\d+]]
local m = ngx.re.match("hello, 1234", regex)
if m then ngx.say(m[0]) else ngx.say("not matched!") end
';
}
# evaluates to "1234"



　　这个自己翻译了
　　Here, [[\\d+]] is stripped down to [[\d+]] by the Nginx config file parser and this is processed correctly.
　　Note that a longer from of the long bracket, [=[...]=], may be required if the regex pattern contains [...] sequences. The [=[...]=] form may be used as the default form if desired.

    # nginx.conf
location /test {
content_by_lua '
local regex = [=[[0-9]+]=]
local m = ngx.re.match("hello, 1234", regex)
if m then ngx.say(m[0]) else ngx.say("not matched!") end
';
}
# evaluates to "1234"



　　如果采用 content_by_lua_file 'test.lua'  \\\\d+ 简化为 \\d+

    -- test.lua
local regex = "\\d+"
local m = ngx.re.match("hello, 1234", regex)
if m then ngx.say(m[0]) else ngx.say("not matched!") end
-- evaluates to "1234"



　　如果采用 content_by_lua_file 'test.lua'   [[\\d+]] 简化为  [[\d+]]

    -- test.lua
local regex = [[\d+]]
local m = ngx.re.match("hello, 1234", regex)
if m then ngx.say(m[0]) else ngx.say("not matched!") end
-- evaluates to "1234"



　　来源：http://wiki.nginx.org/HttpLuaModule