Added comment to function

cmd/main.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"slices"
 
 	"github.com/fatih/color"
 
@@ -25,6 +26,8 @@ func main() {
 	multiLineFlag := flag.Bool("t", false, "Multi-line mode. Treats newline just like any character.")
 	printMatchesFlag := flag.Bool("p", false, "Prints start and end index of each match. Can only be used with '-t' for multi-line mode.")
 	caseInsensitiveFlag := flag.Bool("i", false, "Case-insensitive. Disregard the case of all characters.")
+	recursiveFlag := flag.Bool("r", false, "Recursively search all files in the given directory.")
+	lineNumFlag := flag.Bool("n", false, "For each line with a match, print the line number. Implies -l.")
 	matchNum := flag.Int("m", 0, "Print the match with the given index. Eg. -m 3 prints the third match.")
 	substituteText := flag.String("s", "", "Substitute the contents of each match with the given string. Overrides -o and -v")
 	flag.Parse()
@@ -58,31 +61,71 @@ func main() {
 		panic("Invalid match number to print.")
 	}
 
+	// Enable lineFlag if lineNumFlag is enabled
+	if *lineNumFlag {
+		*lineFlag = true
+	}
+
 	// Process:
 	// 1. Convert regex into postfix notation (Shunting-Yard algorithm)
 	// 		a. Add explicit concatenation operators to facilitate this
 	// 2. Build NFA from postfix representation (Thompson's algorithm)
 	// 3. Run the string against the NFA
 
-	if len(flag.Args()) != 1 { // flag.Args() also strips out program name
+	if len(flag.Args()) < 1 { // flag.Args() also strips out program name
-		fmt.Println("ERROR: Missing cmdline args")
+		fmt.Printf("%s: ERROR: Missing cmdline args\n", os.Args[0])
+		os.Exit(22)
+	}
+	if *recursiveFlag && len(flag.Args()) < 2 { // File/Directory must be provided with '-r'
+		fmt.Printf("%s: ERROR: Missing cmdline args\n", os.Args[0])
 		os.Exit(22)
 	}
 	var re string
 	re = flag.Args()[0]
+	var inputFiles []*os.File
+	if len(flag.Args()) == 1 || flag.Args()[1] == "-" { // Either no file argument, or file argument is "-"
+		if !slices.Contains(inputFiles, os.Stdin) {
+			inputFiles = append(inputFiles, os.Stdin) // os.Stdin cannot be entered more than once into the file list
+		}
+	} else {
+		inputFilenames := flag.Args()[1:]
+		for _, inputFilename := range inputFilenames {
+			inputFile, err := os.Open(inputFilename)
+			if err != nil {
+				fmt.Printf("%s: %s: No such file or directory\n", os.Args[0], inputFilename)
+			} else {
+				fileStat, err := inputFile.Stat()
+				if err != nil {
+					fmt.Printf("%v\n", err)
+					os.Exit(2)
+				} else {
+					if fileStat.Mode().IsDir() {
+						fmt.Printf("%s: %s: Is a directory\n", os.Args[0], inputFilename)
+					} else {
+						inputFiles = append(inputFiles, inputFile)
+					}
+				}
+			}
+		}
+	}
+
 	var test_str string
 	var err error
 	var linesRead bool // Whether or not we have read the lines in the file
 	lineNum := 0       // Current line number
-	// Create reader for stdin and writer for stdout
+	// Create writer for stdout
-	reader := bufio.NewReader(os.Stdin)
 	out := bufio.NewWriter(os.Stdout)
-
+	// Compile regex
 	regComp, err := reg.Compile(re, flagsToCompile...)
 	if err != nil {
 		fmt.Println(err)
 		return
 	}
+
+	for _, inputFile := range inputFiles {
+		lineNum = 0
+		reader := bufio.NewReader(inputFile)
+		linesRead = false
 		for true {
 			if linesRead {
 				break
@@ -174,6 +217,13 @@ func main() {
 			if *lineFlag {
 				if !(*invertFlag) && len(matchIndices) == 0 || *invertFlag && len(matchIndices) > 0 {
 					continue
+				} else {
+					if *recursiveFlag || len(flag.Args()) > 2 { // If we have 2 args, then we're only searching 1 file. We should only print the filename if there's more than 1 file.
+						color.New(color.FgMagenta).Fprintf(out, "%s:", inputFile.Name()) // Print filename
+					}
+					if *lineNumFlag {
+						color.New(color.FgGreen).Fprintf(out, "%d:", lineNum) // Print filename
+					}
 				}
 			}
 
@@ -201,7 +251,7 @@ func main() {
 			} else {
 				for i, c := range test_str_runes {
 					if indicesToPrint.contains(i) {
-					color.New(color.FgRed).Fprintf(out, "%c", c)
+						color.New(color.FgRed, color.Bold).Fprintf(out, "%c", c)
 						// Newline after every match - only if -o is enabled and -v is disabled.
 						if *onlyFlag && !(*invertFlag) {
 							for matchIdxNum, idx := range matchIndices {
@@ -230,4 +280,5 @@ func main() {
 				fmt.Println()
 			}
 		}
+	}
 }

regex/compile.go

@@ -47,6 +47,7 @@ func (re *Reg) UnmarshalText(text []byte) error {
 	return err
 }
 
+// Longest makes future searches prefer the longest branch of an alternation, as opposed to the leftmost branch.
 func (re *Reg) Longest() {
 	re.preferLongest = true
 }

regex/nfa.go

@@ -45,10 +45,10 @@ type nfaState struct {
 	groupBegin                 bool       // Whether or not the node starts a capturing group
 	groupEnd                   bool       // Whether or not the node ends a capturing group
 	groupNum                   int        // Which capturing group the node starts / ends
-	// The following properties depend on the current match - I should think about resetting them for every match.
-	threadGroups    []Group // Assuming that a state is part of a 'thread' in the matching process, this array stores the indices of capturing groups in the current thread. As matches are found for this state, its groups will be copied over.
 	isBackreference            bool       // Whether or not current node is backreference
 	referredGroup              int        // If current node is a backreference, the node that it points to
+	// The following properties depend on the current match - I should think about resetting them for every match.
+	threadGroups  []Group // Assuming that a state is part of a 'thread' in the matching process, this array stores the indices of capturing groups in the current thread. As matches are found for this state, its groups will be copied over.
 	threadBackref int     // If current node is a backreference, how many characters to look forward into the referred group
 }
 
@@ -86,6 +86,8 @@ func cloneStateHelper(stateToClone *nfaState, cloneMap map[*nfaState]*nfaState)
 		groupEnd:        stateToClone.groupEnd,
 		groupBegin:      stateToClone.groupBegin,
 		groupNum:        stateToClone.groupNum,
+		isBackreference: stateToClone.isBackreference,
+		referredGroup:   stateToClone.referredGroup,
 	}
 	cloneMap[stateToClone] = clone
 	for i, s := range stateToClone.output {

regex/re_test.go

@@ -117,6 +117,7 @@ var reTests = []struct {
 	{`\d{3,4}`, nil, "ababab555", []Group{{6, 9}}},
 	{`\bpaint\b`, nil, "paints", []Group{}},
 	{`\b\w{5}\b`, nil, "paint", []Group{{0, 5}}},
+	{`\w{}`, nil, "test", nil},
 	{`[^\w]`, nil, "abcdef1230[]qq';;'", []Group{{10, 11}, {11, 12}, {14, 15}, {15, 16}, {16, 17}, {17, 18}}},
 	{`[^\W]`, nil, "abcdef1230[]qq';;'", []Group{{0, 1}, {1, 2}, {2, 3}, {3, 4}, {4, 5}, {5, 6}, {6, 7}, {7, 8}, {8, 9}, {9, 10}, {12, 13}, {13, 14}}},
 	{`[\[\]]`, nil, "a[b[l]]", []Group{{1, 2}, {3, 4}, {5, 6}, {6, 7}}},
@@ -547,6 +548,20 @@ var reTests = []struct {
 	{`[\p{Greek}\p{Cyrillic}]`, nil, `ΣωШД`, []Group{{0, 1}, {1, 2}, {2, 3}, {3, 4}}},
 
 	{`(?<=\().*?(?=\))`, nil, `(abc)`, []Group{{1, 4}}},
+
+	{`((a|b)\2)`, nil, `aa`, []Group{{0, 2}}},
+	{`((a|b)\2)`, nil, `bb`, []Group{{0, 2}}},
+	{`((a|b)\2)`, nil, `ab`, []Group{}},
+	{`((a|b)\2)`, nil, `ba`, []Group{}},
+
+	{`((a|b)\2){3}`, nil, `aaaaaa`, []Group{{0, 6}}},
+	{`((a|b)\2){3}`, nil, `bbbbbb`, []Group{{0, 6}}},
+	{`((a|b)\2){3}`, nil, `bbaaaa`, []Group{{0, 6}}},
+	{`((a|b)\2){3}`, nil, `aabbaa`, []Group{{0, 6}}},
+	{`((a|b)\2){3}`, nil, `aaaabb`, []Group{{0, 6}}},
+	{`((a|b)\2){3}`, nil, `bbaabb`, []Group{{0, 6}}},
+	{`((a|b)\2){3}`, nil, `baabab`, []Group{}},
+	{`((a|b)\2){3}`, nil, `bbabab`, []Group{}},
 }
 
 var groupTests = []struct {

regex/todo.txt

@@ -4,4 +4,5 @@
 Ideas for flags:
     -m <num> : Print <num>th match (-m 1 = first match, -m 2 = second match)
     -g <num> : Print the <num>th group
+    -r : Specify a directory instead of a file, reads recursively
 4. Refactor code for flags - make each flag's code a function, which modifies the result of findAllMatches