App 08 - String Processing

--# Main
-- Appetizer 08 - Text Processing

-- Bruce Elliott
-- May 2013

function setup()

-- String Library Tutorial at
--        lua-users.org/wiki/StringLibraryTutorial
-- Patterns Tutorial at
--        lua-users.org/wiki/PatternsTutorial
-- were used in this Appetizer. Some code was used or modified

-- There are a large number of examples of how individual string
-- statements can be used.  Why you would use string proceesing is up to you.

-- String format specifiers
-- '%a' is all letters
-- '%d' is all digits
-- '%l' is all lower case characters
-- '%u' is all upper case characters
-- '%s' is a space character
-- '[aeiou]' match any character in set
-- '[^aeiou]' match all but characters in set
-- 'w(...)' match w followed by any three characters - Captures
-- 'an*' match longest zero or more repetitions of pattern
-- 'an+' match one or more repetitions of pattern
-- 'an-' match shortest zero or more repetitions of pattern
-- 'an?' match zero or one occurrences of pattern

-- Captures can be marked using parentheses: "q(...)"

myString = "The quick brown fox jumped over the lazy dog. The fox jumped back."
myString2 = "There are 15 apples out of 38 fruits and 76 tomatos"
sTab =""

-- string.find(s, pattern, init, plain)

-- Looks for the first match of pattern in the string s.

-- s - is string to search
-- pattern - Find first match of pattern
-- init - starting point for search
-- plain - find substring no "magic" characters
-- returns - start, end indices of match plus captures if any
--        - returns nil if no match

print("string.find()")

strt, stop, sTab = string.find(myString, "%a")
disTab(strt, stop, sTab)
--> 1 1        First letter is at position 1

strt, stop, sTab = string.find(myString, "%d")
disTab(strt, stop, sTab)
--> nil        There are no digits

strt, stop, sTab = string.find(myString2, "%d")
disTab(strt, stop, sTab)
--> 11 11        The first ddigit is at position 11

strt, stop, sTab = string.find(myString, "%l")
disTab(strt, stop, sTab)
--> 2 2    First lower case char

strt, stop, sTab = string.find(myString, "%u")
disTab(strt, stop, sTab)
--> 1 1    First upper case char

strt, stop, sTab = string.find(myString, "%s")
disTab(strt, stop, sTab)
--> 4 4    first space char

strt, stop, sTab = string.find(myString, "[wpt]")
disTab(strt, stop, sTab)
--> 14 14   First char in w p t (brown)

strt, stop, sTab = string.find(myString, "[^wpt]")
disTab(strt, stop, sTab)
--> 1 1    First char not in wpt (T is not t)

strt, stop, sTab = string.find(myString, "o(.)")
disTab(strt, stop, sTab)
--> 13 14 w    First match of 'o' followed by any one char (brown)

strt, stop, sTab = myString:find("o(.)")
disTab(strt, stop, sTab)
--> 13 14 w    myString:find() instead of string.find(myString, )

strt, stop, sTab = string.find(myString2, "pl*")
disTab(strt, stop, sTab)
--> 15 15    First p in apple

strt, stop, sTab = string.find(myString2, "ck*")
disTab(strt, stop, sTab)
--> nil    ck does not appear in string

strt, stop = string.find("bananas", 'az*')
disTab(strt, stop, sTab)
--> 2 2

strt, stop = string.find("bananas", 'an*')
disTab(strt, stop)
--> 2 3

strt, stop  = string.find("bannnnnanas", 'an*')
disTab(strt, stop)
--> 2 7        Notice ending point of 7

strt, stop, sTab = string.find(myString2, "pl+")
disTab(strt, stop, sTab)
--> 16 17    First pl in apple

strt, stop = string.find("bananas", 'an+')
disTab(strt, stop)
--> 2 3        Same result as 'an*'

strt, stop  = string.find("bannnnnanas", 'an+')
disTab(strt, stop)
--> 2 7        Same resukt as 'an*'

strt, stop, sTab = string.find(myString2, "pl-")
disTab(strt, stop, sTab)
--> 15 15    First p in apple

strt, stop = string.find("bananas", 'an-')
disTab(strt, stop)
--> 2 2       Compare to 'an*'

strt = string.find("bannnnnanas", 'an-')
disTab(strt, stop)
--> 2 2     Compare to 'an*'

strt, stop, sTab = string.find(myString2, "pl?")
disTab(strt, stop, sTab)
--> 15 15    First p in apple

strt, stop, sTab = string.find(myString, "ox", 20)
disTab(strt, stop, sTab)
--> 52 53    First match starting at position 20 from start

strt, stop, sTab = string.find(myString, "ox", -20)
disTab(strt, stop, sTab)
--> 52 53    First match starting 20 characters from the end


-- string.format(formatstring, ..., target)

-- Returns a formatted version of its variable arguments
-- following the description given in the first argument,
-- which must be a string

-- formatstring - % and one or more of the following
-- target - value(s) to be formatted
-- Returns: A formatted string

-- Format specifiers must be preceded by a "%"
-- c, d, E, e, f, g, i, o, u, X, and x all expect a number
-- q and s expect a string

print("string.format()")

print(string.format("%c %d %E %e", 65, 2, 3, 4))
-- prints char w/val 65, int, EXP, exp

print(string.format("%f %g", 5.67, 6))
-- prints float, gen (int)

print(string.format("%i %o %u %u %X %x", 5.5, 15, -2, 2, 11, 11))
-- prints whole num, octal, unsigned int, unsig int, HEX (upper), hex (lower)

num = 56
newStr = string.format("%s %d", "The number is", num)
print(newStr)
--> The number is 56

num = 56
newStr = string.format("The number is %d", num)
print(newStr)
--> The number is 56

ch = 'r'
newStr = string.format("%s %s", "The char is", ch)
print(newStr)
--> The char is r         "%s" prints a string

ch = 'r'
newStr = string.format("%s %q", "The char is", ch)
print(newStr)
--> The char is "r"        "%q" puts quotes around string

-- string.len(s)

-- Receives a string and returns its length

-- s - String to find length
-- Returns: Length of the string s

print("string.len()")

strt = string.len(myString)
print(strt)
--> 66

strt = myString:len()
print(strt)
--> 66    Note format

-- string.lower(s)

-- Receives a string and returns a copy of this string
-- with all uppercase letters changed to lowercase.

-- s - String to convert to all lower case
-- Returns - Length of string s

print("string.lower()")

strt = string.lower(myString)
print(strt)
--> the quick brown fox jumped over the lazy dog. the fox jumped back.

strt = myString:lower()
print(strt)
--> the quick brown fox jumped over the lazy dog. the fox jumped back.

-- string.upper(s)

--Recieves a string and returns a copy of this string
-- with all lowercase letters changes to uppercase.

-- s - String to convert to all upper case

-- Returns - Uppercase version of string s

print("string.upper()")

strt = string.upper(myString)
print(strt)
--> THE QUICK BROWN FOX JUMPED OVER THE LAZY DOG. THE FOX JUMPED BACK

strt = myString:upper()
print(strt)
--> THE QUICK BROWN FOX JUMPED OVER THE LAZY DOG. THE FOX JUMPED BACK

-- string.match(s, pattern, init)

-- Looks for the first match of pattern in the string s.

-- s - String to search
-- pattern - pattern to match
-- init - starting location in the string

-- returns - Captures from the first match of pattern
-- in string s, or nil if none were found.

-- Note: position information is not available

print("string.match()")

strt = string.match(myString, "the")
print(strt)
--> the

strt = string.match(myString, "t(..)")
print(strt)
--> he

strt = string.match("I have 2 questions for you", "%a %a")
print(strt)
--> I h         Match a char followd by a char

strt = string.match("I have 2 questions for you", "%a+ %a+")
print(strt)
--> I have        Match any number of chars followed by any number of chars

strt = string.match("I have 2 questions for you", "%d+ %a+")
print(strt)
--> 2 questions    Match one or more digits followed by one or more chars

strt = myString:match("b(....)")
print(strt)
--> rown

-- string.rep(s, n)

-- Returns a string that is the concatenation of n copies
-- of the string s.

-- s - String to replicate
-- n - int, number of times to replicate the string

-- Returns - n concatenations of string s

print("string.rep()")

strt = string.rep("abc", 5)
print(strt)
--> abcabcabcabcabc
str = "abc"
strt = str:rep(5)
print(strt)
--> abcabcabcabcabc

-- string.sub(s, i, j)

-- Returns the substring of s that starts at i
-- and continues until j; i and j can be negative.

-- s - find substring of this string
-- i - int, starting index
-- j - int, ending index

-- Returns - Substring of string s

print("string.sub()")

strt = string.sub(myString, 5, 8)
print(strt)
--> quic

strt = myString:sub(5, 9)
print(strt)
--> quick

-- string.gsub(s, pattern, replace, n)

-- It can replace all instances of the pattern
-- provided with the replace string.

-- s - Original string
-- pattern - The string to replace
-- replace - New string
-- n - Used to limit the number of substitutions made

-- Returns - the modified string and the
--    number of substitutions

print("string.gsub()")

strt, stop = string.gsub(myString, "fox", "mouse", 1)
print(strt)
print(stop)
--> The quick brown mouse jumped over the lazy dog. The fox jumped back.
--> 1

str = "123123123"
strt, stop = str:gsub("2", "8")
print(strt)
print(stop)
--> 183183183
--> 3

str = "The quick {brown} fox jumped {over} the {lazy dog}."
strt, stop = string.gsub(str,"{(.-)}", function(a) print(a) end)
print(stop)
--> brown
--> over
--> lazy dog
--> 3

-- Note: This example used an anonymous function as the third parameter
--        the function accepted each capture and printed it

str = "The quick {brown} fox jumped {over} the {lazy dog}."
strt, stop = string.gsub(str,"{(.-)}", myFunc)
print(strt)
print(stop)
--> brown
--> over
--> lazy dog
--> The quick rep fox jumped rep the rep.
--> 3

-- Note: Each capture is displayed by the function myFunc()
--        myFunc returns "rep" which is substituted for
--        the capture in the original string
--        I replaced the function with the table sTab,
--        which seems to be permitted. I was not able to
--        display any table elements

-- string.gmatch(s, pat)

-- This returns a pattern finding iterator. The iterator will search through
-- the string passed looking for instances of the pattern you passed.

-- s - The string to search
-- pat - the pattern to match

-- Returns iterator

print("string.gmatch()")

for word in string.gmatch("Hello Codea user", "%a+") do
    print(word)
end

-- Note: the use of gmatch in a for loop

strt = string.gmatch("Hello Codea user", "%a+")

for word in strt do
    print(word)
end

--> Hello
--> Codea
--> user

-- Note: strt is a function returned by string.gmatch()
--        Change "%a+" to "%a" and see how the output changes
--

-- string.reverse(s)

-- Reverses a string

-- s - String to reverse

-- Returns - string reversed

print("string.reverse()")

strt = string.reverse("Hello Codea user")
print(strt)
--> resu aedoC olleH

str = "This is an example"
strt = str:reverse()
print(strt)
--> elpmaxe na si sihT



end

function disTab(beg, lst, nTab)
    if beg ~= nil and lst ~= nil then
        print(beg.." "..lst)
    else
        print("nil")
    end
    if nTab ~= nil then
        print(nTab)
    end

end

function myFunc(value)
    print(value)
    return("rep")
end