check that string starts and ends with a specific pattern in Lua

Question

I have a table which is having string values

data_table = {'(?P<smartcache>.+)$', 'css', '123454', '(?P<version>.+)$'}

I am trying to see if a string startswith '(?P<' and endswith ')$' . I want a string in output which will be like

output_table = '/smartcache/css/123454/version'

I am facing problem to fetch values which are passed with patterns like I want to fetch 'smartcache' from (?P<smartcache>.+)$ .

My Try:

out_string_value = (string.match(uri_regex, '[^(?P<].+[)$]')

here I am getting output as smartcache>.+)$ but I want smartcache .

Answer 1

local uri_regex = '(?P<smartcache>.+)$'
local out_string_value = uri_regex:match('^%(%?P<([^>]+)>.*%)%$$')
print(out_string_value)

The Lua pattern ^%(%?P<([^>]+)>.*%)%$$ is similar to the regex ^\\(\\?P<([^>]+)>.*\\)\\$$ except that Lua pattern uses % to escape magic characters.

Answer 2

I don't know the intricacies of Lua Pattern syntax, but in regex terms, this would be the pattern:

^\(\?P<([^>]+)>.*\)\$$

On the regex demo , you can see the match.

• The ^ anchor asserts that we are at the beginning of the string
• \\( matches an opening bracket
• \\? matches a question mark
• P< matches literal characters
• ([^>]+) captures any chars that are not > to Group 1
• > matches literal char
• .* matches any chars
• \\) matches a closing bracket
• \\$ matches a dollar
• The $ anchor asserts that we are at the end of the string