Initial Version

pkg/grep/search.go:

package grep

import (
	"bufio"
	"os"
	"regexp"
	"strings"
)

func Grep(pattern string, filePath string) ([]string, error) {
	file, err := os.Open(filePath)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	var matchingLines []string
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := scanner.Text()
		match, err := regexp.MatchString(pattern, line)
		if err != nil {
			return nil, err
		}
		if match {
			matchingLines = append(matchingLines, strings.TrimLeft(line, " \t"))
		}
	}

	if err := scanner.Err(); err != nil {
		return nil, err
	}

	return matchingLines, nil
}

regexp package provides support for regular expressions. Regular expressions (regex or regexp) are patterns that describe sets of strings.

main.go:

package main

import (
	"flag"
	"fmt"
	"log"

	"github.com/Literank/gorep/pkg/grep"
)

func main() {
	flag.Parse()

	// Retrieve positional arguments
	// pattern - The pattern to search for
	// file_path - The path to the file to search in
	args := flag.Args()

	if len(args) < 2 {
		log.Fatal("Both pattern and file_path are required")
	}

	result, err := grep.Grep(args[0], args[1])
	if err != nil {
		log.Fatal(err)
	}

	for _, line := range result {
		fmt.Println(line)
	}
}

flag package provides a convenient way to define and parse command-line arguments, including both flags and positional arguments. It's a standard library package that simplifies the process of handling command-line input for your programs.

Run the program like this:

# search "result" in file main.go
go run main.go result main.go

You will get result lines like below:

result, err := grep.Grep(args[0], args[1])
for _, line := range result {