string.gsub can search and replace a pattern. The replacement can be a string, table or function. It returns the transformed string and the amount of matches found.
If it is a string, then each match becomes that string.
local source = "pear cheese ROCK CHEESE"
print(source:gsub("cheese", "fish"))
-- pear fish ROCK CHEESE 1
print(source:gsub("%w+", "fish")) -- %w is any word character, so %w+ is a sequence of one or more of these
-- fish fish fish fish 4
If it is a table, then the table is indexed for something to replace the match with. If the match isn’t found in the table (returns nil), then it isn’t changed.
local source = "pear cheese ROCK CHEESE"
local replacements = {
pear = "moldy",
CHEESE = "rock",
}
print(source:gsub("%w+", replacements))
-- moldy cheese ROCK rock 4
If it is a function, then it is called with each matching string.
local source = "pear cheese rock cheese"
local function func(match)
return ({"bear", "ear", "gear", "dear"})[math.random(4)]
end
print(source:gsub("cheese", func))
-- pear bear rock gear 2
-- pear bear rock ear 2
-- pear ear rock ear 2
-- etc.
local filters = {
{
search = {"cheese"}, -- that's a table in a table in a table
replace = {"one", "two", "three", "four", "five", "six", "seven"},
}, {
search = {"pear", "rock"},
replace = {"red", "green", "blue"}
}
}
local function func(match)
match = string.lower(match)
for _,filter in ipairs(filters) do
if table.find(filter.search, match) then
return filter.replace[math.random(#filter.replace)]
end
end
-- returns nil implicitly
end
for i = 1,10 do
print(source:gsub("%w+", func))
end
-- red four red six 4
-- green five red six 4
-- red one blue three 4
-- blue three green one 4
-- blue six blue five 4
-- blue two red one 4
-- red six blue two 4
-- red four red one 4
-- green six blue four 4
-- red four red five 4
-- etc.