Format string to fit pattern in Lua?

Question

Say I have a pattern, and a string:

String  = "ABCDEF"
Pattern = "%w%w%w - %w%w%w"

How can I make String match the format of Pattern, so it becomes "ABC - DEF"?

Answer 1

Use string.gsub:

string.gsub("ABCDEF", "(%w%w%w)(%w%w%w)", "%1 - %2")

Note that this would replaces all the occurrences of the pattern.

Answer 2

There no one to one match beetween string, pattern and capture. Same capture can be produced by several patterns for same string. Also if "%w%w%w - %w%w%w" in your example is Lua string pattern then string "ABC - DEF" does not match to it. Patterns that match to it can be %w%w%w %- %w%w%w or %w+%W+%w+ or %w*%s*.%s*%w* or several others. So I suggest define your own subset of rules that you really need and implement your own function to handle it.