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Go/strings/bom/bom.go at master · gitgitcode/Go · GitHub
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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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