Use string.gsub to replace strings, but only whole words

Question

I have a search replace script which works to replace strings. It already has options to do case insensitive searches and \"escaped\" matches (eg allows searching for % ( et

Answer 1

have a way of doing what I want now, but it's inelegant. Is there a better way?

There is an undocumented feature of Lua's pattern matching library called the Frontier Pattern, which will let you write something like this:

function replacetext(source, find, replace, wholeword)
  if wholeword then
    find = '%f[%a]'..find..'%f[%A]'
  end
  return (source:gsub(find,replace))
end

local source  = 'test testing this test of testicular footest testimation test'
local find    = 'test'
local replace = 'XXX'
print(replacetext(source, find, replace, false))  --> XXX XXXing this XXX of XXXicular fooXXX XXXimation XXX    
print(replacetext(source, find, replace, true ))   --> XXX testing this XXX of testicular footest testimation XXX

Answer 2

do you mean if you pass nocase() foo, you want [fooFOO] instead of [fF][oO][oO]? if so, you could try this?

function nocase (s)
      s = string.gsub(s, "(%a+)", function (c)
            return string.format("[%s%s]", string.lower(c),
                                           string.upper(c))
          end)
      return s
end

and if you want an easy way to split a sentence into words, you can use this:

function split(strText)
    local words = {}
    string.gsub(strText, "(%a+)", function(w)
                                    table.insert(words, w)
                                  end)
    return words
end

once you've gotten the words split, it's pretty easy to iterate over the words in the table and do a full comparison against each word.