package Scanner
import BigString

/*
*	Seuqentially returns substrings of an input string based on delimiters.
*  (Regex not supported)
*/
public enum ReturnMode
	TOKEN_ONLY
	TOKEN_PLUS_DELIM
	TOKEN_AND_DELIM

public class Delimiter
	string token
	int length
	Delimiter prev = null

	construct(string token)
		this.token = token
		length = token.length()

public class Scanner
	BigString bigInput = null
	Delimiter lastDelimiter = null
	int tokenLength = 0
	ReturnMode returnMode = ReturnMode.TOKEN_ONLY

	function setActiveDelimiter(Delimiter delim)
		delim.prev = null
		lastDelimiter = delim

	function setInput(BigString bigString)
		bigInput = bigString
		tokenLength = 0

	function addDelimiter(string delim)
		addDelimiter(new Delimiter(delim))

	function addDelimiter(Delimiter delim)
		delim.prev = lastDelimiter
		lastDelimiter = delim

	function hasNext() returns boolean
		if bigInput.getLength() > 0
			if returnMode == ReturnMode.TOKEN_ONLY
				var delim = lastDelimiter
				while delim != null
					if bigInput.getLength() == delim.length and bigInput.getString(0, delim.length) == delim.token
						return false
					delim = delim.prev
			return true
		return false

	function next() returns string
		string token = ""
		tokenLength = 0
		while tokenLength <= bigInput.getLength()
			// Length doesn't exceed input string, check all delimiters
			var delim = lastDelimiter
			while delim != null
				if bigInput.getLength() >= tokenLength+delim.length and bigInput.getString(tokenLength, delim.length) == delim.token
					// Found delimiter
					if tokenLength == 0
						// Token is only delimiter, return depending on mode
						switch returnMode
							case TOKEN_ONLY
								token = ""
								tokenLength--
								bigInput.startoffset += delim.length
							case TOKEN_PLUS_DELIM
							case TOKEN_AND_DELIM
								token = bigInput.getString(0, delim.length)
								bigInput.startoffset += delim.length
					else
						switch returnMode
							case TOKEN_ONLY
								token = bigInput.getString(0, tokenLength)
								bigInput.startoffset += token.length()+delim.length
							case TOKEN_PLUS_DELIM
								token = bigInput.getString(0, tokenLength+delim.length)
								bigInput.startoffset += token.length()+delim.length
							case TOKEN_AND_DELIM
								token = bigInput.getString(0, tokenLength)
								bigInput.startoffset += token.length()
						
					break
				delim = delim.prev
			if token.length() > 0
				break
			tokenLength ++
		if token.length() < 1
			token = bigInput.getString(0)
			bigInput.startoffset += token.length()
		
		return token

	function close()
		destroy this

	function iterator() returns Scanner
		return this