Bom

𝔸𝕝𝕘𝕖𝕣

package bom

// User defined.
// Set to true to print various extra stuff out (slows down the execution)
// Set to false for quick and quiet execution.
// const debugMode bool = false

// User defined.
// Set to true to read input from two command line arguments
// Set to false to read input from two files "pattern.txt" and "text.txt"
// const commandLineInput bool = false

// Implementation of Backward Oracle Matching algorithm (Factor based approach).
// Requires either a two command line arguments separated by a single space,
// or two files in the same folder: "pattern.txt" containing the string to
// be searched for, "text.txt" containing the text to be searched in.
// func main() {
// 	if commandLineInput == true { // case of command line input
// 		args := os.Args
// 		if len(args) <= 2 {
// 			log.Fatal("Not enough arguments. Two string arguments separated by spaces are required!")
// 		}
// 		pattern := args[1]
// 		s := args[2]
// 		for i := 3; i < len(args); i++ {
// 			s = s + " " + args[i]
// 		}
// 		if len(args[1]) > len(s) {
// 			log.Fatal("Pattern  is longer than text!")
// 		}
// 		if debugMode == true {
// 			fmt.Printf("\nRunning: Backward Oracle Matching algorithm.\n\n")
// 			fmt.Printf("Search word (%d chars long): %q.\n", len(args[1]), pattern)
// 			fmt.Printf("Text        (%d chars long): %q.\n\n", len(s), s)
// 		} else {
// 			fmt.Printf("\nRunning: Backward Oracle Matching algorithm.\n\n")
// 		}
// 		bom(s, pattern)
// 	} else if commandLineInput == false { // case of file line input
// 		patFile, err := ioutil.ReadFile("pattern.txt")
// 		if err != nil {
// 			log.Fatal(err)
// 		}
// 		textFile, err := ioutil.ReadFile("text.txt")
// 		if err != nil {
// 			log.Fatal(err)
// 		}
// 		if len(patFile) > len(textFile) {
// 			log.Fatal("Pattern  is longer than text!")
// 		}
// 		if debugMode == true {
// 			fmt.Printf("\nRunning: Backward Oracle Matching algorithm.\n\n")
// 			fmt.Printf("Search word (%d chars long): %q.\n", len(patFile), patFile)
// 			fmt.Printf("Text        (%d chars long): %q.\n\n", len(textFile), textFile)
// 		} else {
// 			fmt.Printf("\nRunning: Backward Oracle Matching algorithm.\n\n")
// 		}
// 		bom(string(textFile), string(patFile))
// 	}
// }

// // Function bom performing the Backward Oracle Matching algorithm.
// // Prints whether the word/pattern was found + positions of possible multiple occurrences
// // or that the word was not found.
// func bom(t, p string) {
// 	startTime := time.Now()
// 	n, m := len(t), len(p)
// 	var current, j, pos int
// 	oracle := oracleOnLine(reverse(p))
// 	occurrences := make([]int, len(t))
// 	currentOcc := 0
// 	pos = 0
// 	if debugMode == true {
// 		fmt.Printf("\n\nWe are reading backwards in %q, searching for %q\n\nat position %d:\n", t, p, pos+m-1)
// 	}
// 	for pos <= n-m {
// 		current = 0 //initial state of the oracle
// 		j = m
// 		for j > 0 && stateExists(current, oracle) {
// 			if debugMode == true {
// 				prettyPrint(current, j, n, pos, t, oracle)
// 			}
// 			current = getTransition(current, t[pos+j-1], oracle)
// 			j--
// 		}
// 		if stateExists(current, oracle) {
// 			if debugMode == true {
// 				fmt.Printf(" We got an occurrence!")
// 			}
// 			occurrences[currentOcc] = pos
// 			currentOcc++
// 		}
// 		pos = pos + j + 1
// 		if pos+m-1 < len(t) {
// 			if debugMode == true {
// 				fmt.Printf("\n\nposition %d:\n", pos+m-1)
// 			}
// 		}
// 	}
// 	elapsed := time.Since(startTime)
// 	fmt.Printf("\n\nElapsed %f secs\n", elapsed.Seconds())
// 	fmt.Printf("\n\n")
// 	if currentOcc > 0 {
// 		fmt.Printf("Word %q was found %d times at positions: ", p, currentOcc)
// 		for k := 0; k < currentOcc-1; k++ {
// 			fmt.Printf("%d, ", occurrences[k])
// 		}
// 		fmt.Printf("%d", occurrences[currentOcc-1])
// 		fmt.Printf(".\n")
// 	}
// 	if currentOcc == 0 {
// 		fmt.Printf("\nWord was not found.\n")
// 	}
// 	return
// }

// // Construction of the factor oracle automaton for a word p.
// func oracleOnLine(p string) (oracle map[int]map[uint8]int) {
// 	if debugMode == true {
// 		fmt.Printf("Oracle construction: \n")
// 	}
// 	oracle = make(map[int]map[uint8]int)
// 	supply := make([]int, len(p)+2) // supply function
// 	createNewState(0, oracle)
// 	supply[0] = -1
// 	var orP string
// 	for j := 0; j < len(p); j++ {
// 		oracle, orP = oracleAddLetter(oracle, supply, orP, p[j])
// 	}
// 	return oracle
// }

// // Adds one letter to the oracle.
// func oracleAddLetter(oracle map[int]map[uint8]int, supply []int, orP string, o uint8) (oracleToReturn map[int]map[uint8]int, orPToReturn string) {
// 	m := len(orP)
// 	var s int
// 	createNewState(m+1, oracle)
// 	createTransition(m, o, m+1, oracle)
// 	k := supply[m]
// 	for k > -1 && getTransition(k, o, oracle) == -1 {
// 		createTransition(k, o, m+1, oracle)
// 		k = supply[k]
// 	}
// 	if k == -1 {
// 		s = 0
// 	} else {
// 		s = getTransition(k, o, oracle)
// 	}
// 	supply[m+1] = s
// 	return oracle, orP + string(o)
// }

// // Function that takes a single string and reverses it.
// // @author 'Walter' http://stackoverflow.com/a/10043083
// func reverse(s string) string {
// 	l := len(s)
// 	m := make([]rune, l)
// 	for _, c := range s {
// 		l--
// 		m[l] = c
// 	}
// 	return string(m)
// }

// // Automaton function for creating a new state.
// func createNewState(state int, at map[int]map[uint8]int) {
// 	at[state] = make(map[uint8]int)
// 	if debugMode == true {
// 		fmt.Printf("\ncreated state %d", state)
// 	}
// }

// // Creates a transition for function σ(state,letter) = end.
// func createTransition(fromState int, overChar uint8, toState int, at map[int]map[uint8]int) {
// 	at[fromState][overChar] = toState
// 	if debugMode == true {
// 		fmt.Printf("\n    σ(%d,%c)=%d;", fromState, overChar, toState)
// 	}
// }

// // Returns ending state for transition σ(fromState,overChar), -1 if there is none.
// func getTransition(fromState int, overChar uint8, at map[int]map[uint8]int) (toState int) {
// 	if !stateExists(fromState, at) {
// 		return -1
// 	}
// 	toState, ok := at[fromState][overChar]
// 	if ok == false {
// 		return -1
// 	}
// 	return toState
// }

// // Checks if state exists. Returns true if it does, false otherwise.
// func stateExists(state int, at map[int]map[uint8]int) bool {
// 	_, ok := at[state]
// 	if !ok || state == -1 || at[state] == nil {
// 		return false
// 	}
// 	return true
// }

// // Just some printing of extra information about what the algorithm does.
// func prettyPrint(current int, j int, n int, pos int, t string, oracle map[int]map[uint8]int) {
// 	if current == 0 && !(getTransition(current, t[pos+j-1], oracle) == -1) {
// 		fmt.Printf("\n -->(%d)---(%c)--->(%d)", current, t[pos+j-1], getTransition(current, t[pos+j-1], oracle))
// 	} else if getTransition(current, t[pos+j-1], oracle) == -1 && current != 0 {
// 		fmt.Printf("\n    (%d)---(%c)       ", current, t[pos+j-1])
// 	} else if getTransition(current, t[pos+j-1], oracle) == -1 && current == 0 {
// 		fmt.Printf("\n -->(%d)---(%c)       ", current, t[pos+j-1])
// 	} else {
// 		fmt.Printf("\n    (%d)---(%c)--->(%d)", current, t[pos+j-1], getTransition(current, t[pos+j-1], oracle))
// 	}
// 	fmt.Printf(" ")
// 	for a := 0; a < pos+j-1; a++ {
// 		fmt.Printf("%c", t[a])
// 	}
// 	if getTransition(current, t[pos+j-1], oracle) == -1 {
// 		fmt.Printf("[%c]", t[pos+j-1])
// 	} else {
// 		fmt.Printf("[%c]", t[pos+j-1])
// 	}
// 	for a := pos + j; a < n; a++ {
// 		fmt.Printf("%c", t[a])
// 	}
// 	if getTransition(current, t[pos+j-1], oracle) == -1 {
// 		fmt.Printf(" FAIL on the character[%c]", t[pos+j-1])
// 	}
// }
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