Improve cli handling

- Add --regex-posix
- Improve code documentation

Author: mblaschke

README.md

@@ -1,5 +1,5 @@
 # goreplace
-Replace cli utility written in golang
+Cli utility for replacing text in files, written in golang and compiled for usage in Docker images
 
 Inspired by https://github.com/piranha/goreplace
 
@@ -23,9 +23,11 @@ Application Options:
 
 ### Examples
 
-| Command                                                               | Description                                                                                   |
-|-----------------------------------------------------------------------|-----------------------------------------------------------------------------------------------|
-| `goreplace -s foobar -r barfoo file1 file2`                           | Replaces `foobar` to `barfoo` in file1 and file2                                              |
-| `goreplace --regex -s 'foo.*' -r barfoo file1 file2`                  | Replaces the regex `foo.*` to `barfoo` in file1 and file2                                     |
-| `goreplace --regex --ignore-case -s 'foo.*' -r barfoo file1 file2`    | Replaces the regex `foo.*` (and ignore case) to `barfoo` in file1 and file2                   |
-| `goreplace --replace-line -s 'foobar' -r barfoo file1 file2`          | Replaces all lines with content `foobar` to `barfoo` (whole line) in file1 and file2          |
+| Command                                                            | Description                                                                          |
+|:-------------------------------------------------------------------|:-------------------------------------------------------------------------------------|
+| `goreplace -s foobar -r barfoo file1 file2`                        | Replaces `foobar` to `barfoo` in file1 and file2                                     |
+| `goreplace --regex -s 'foo.*' -r barfoo file1 file2`               | Replaces the regex `foo.*` to `barfoo` in file1 and file2                            |
+| `goreplace --regex --ignore-case -s 'foo.*' -r barfoo file1 file2` | Replaces the regex `foo.*` (and ignore case) to `barfoo` in file1 and file2          |
+| `goreplace --replace-line -s 'foobar' -r barfoo file1 file2`       | Replaces all lines with content `foobar` to `barfoo` (whole line) in file1 and file2 |
+
+

goreplace.go

@@ -1,38 +1,40 @@
 package main
 
 import (
-	"fmt"
-	"errors"
-	"bytes"
-	"io/ioutil"
-	"bufio"
-	"os"
-	"strings"
-	"regexp"
-	flags "github.com/jessevdk/go-flags"
+    "fmt"
+    "errors"
+    "bytes"
+    "io/ioutil"
+    "bufio"
+    "os"
+    "strings"
+    "regexp"
+    flags "github.com/jessevdk/go-flags"
 )
 
 const (
-	Author  = "webdevops.io"
-	Version = "0.2.1"
+    Author  = "webdevops.io"
+    Version = "0.2.1"
 )
 
 var opts struct {
-	Search            string   `short:"s"  long:"search"       required:"true"  description:"search term"`
-	SearchRegex       *regexp.Regexp
-	Replace           string   `short:"r"  long:"replace"      required:"true"  description:"replacement term" `
-	IgnoreCase        bool     `short:"i"  long:"ignore-case"                   description:"ignore pattern case"`
-	ReplaceLine       bool     `           long:"replace-line"                  description:"replace whole line instead of only match"`
-	Regex             bool     `           long:"regex"                         description:"treat pattern as regex"`
-	RegexBackref      bool     `           long:"regex-backrefs"                description:"enable backreferences in replace term"`
-	Verbose           bool     `short:"v"  long:"verbose"                       description:"verbose mode"`
-	DryRun            bool     `           long:"dry-run"                       description:"dry run mode"`
-	ShowVersion       bool     `short:"V"  long:"version"                       description:"show version and exit"`
-	ShowHelp          bool     `short:"h"  long:"help"                          description:"show this help message"`
+    Search            string   `short:"s"  long:"search"       required:"true"  description:"search term"`
+    SearchRegex       *regexp.Regexp
+    Replace           string   `short:"r"  long:"replace"      required:"true"  description:"replacement term" `
+    IgnoreCase        bool     `short:"i"  long:"ignore-case"                   description:"ignore pattern case"`
+    ReplaceLine       bool     `           long:"replace-line"                  description:"replace whole line instead of only match"`
+    Regex             bool     `           long:"regex"                         description:"treat pattern as regex"`
+    RegexBackref      bool     `           long:"regex-backrefs"                description:"enable backreferences in replace term"`
+    RegexPosix        bool     `           long:"regex-posix"                   description:"parse regex term as POSIX regex"`
+    Verbose           bool     `short:"v"  long:"verbose"                       description:"verbose mode"`
+    DryRun            bool     `           long:"dry-run"                       description:"dry run mode"`
+    ShowVersion       bool     `short:"V"  long:"version"                       description:"show version and exit"`
+    ShowHelp          bool     `short:"h"  long:"help"                          description:"show this help message"`
 }
 
 // Replace line (if match is found) in file
 func replaceInFile(filepath string) {
+    // try open file
     file, err := os.Open(filepath)
     if err != nil {
         panic(err)
@@ -45,9 +47,12 @@ func replaceInFile(filepath string) {
     line, e := Readln(r)
     for e == nil {
         if searchMatch(line) {
+            // --replace-line
             if opts.ReplaceLine {
+                // replace whole line with replace term
                 line = opts.Replace
             } else {
+                // replace only term inside line
                 line = replaceText(line)
             }
 
@@ -95,6 +100,7 @@ func searchMatch(content string) (bool) {
 
 // Replace text in whole content based on search options
 func replaceText(content string) (string) {
+    // --regex-backrefs
     if opts.RegexBackref {
         return opts.SearchRegex.ReplaceAllString(content, opts.Replace)
     } else {
@@ -104,14 +110,15 @@ func replaceText(content string) (string) {
 
 // Write content to file
 func writeContentToFile(filepath string, content bytes.Buffer) {
+    // --dry-run
     if opts.DryRun {
         title := fmt.Sprintf("%s:", filepath)
 
+        fmt.Println()
         fmt.Println(title)
         fmt.Println(strings.Repeat("-", len(title)))
         fmt.Println(content.String())
         fmt.Println()
-        fmt.Println()
     } else {
         var err error
         err = ioutil.WriteFile(filepath, content.Bytes(), 0)
@@ -131,6 +138,7 @@ func logMessage(message string) {
     }
 }
 
+// Log error object as message
 func logError(err error) {
     fmt.Printf("Error: %s\n", err)
 }
@@ -140,13 +148,16 @@ func logError(err error) {
 func buildSearchTerm() {
     var regex string
 
+    // --regex
     if opts.Regex {
+        // use search term as regex
         regex = opts.Search
     } else {
+        // use search term as normal string, escape it for regex usage
         regex = regexp.QuoteMeta(opts.Search)
     }
 
-
+    // --ignore-case
     if opts.IgnoreCase {
         regex = "(?i:" + regex + ")"
     }
@@ -155,45 +166,50 @@ func buildSearchTerm() {
         logMessage(fmt.Sprintf("Using regular expression: %s", regex))
     }
 
-    opts.SearchRegex = regexp.MustCompile(regex)
+    if opts.RegexPosix {
+        opts.SearchRegex = regexp.MustCompilePOSIX(regex)
+    } else {
+        opts.SearchRegex = regexp.MustCompile(regex)
+    }
 }
 
-func handleSpecialOptions(argparser *flags.Parser, args []string) {
+func handleSpecialCliOptions(argparser *flags.Parser, args []string) {
+    // --version
     if (opts.ShowVersion) {
-        fmt.Printf("goreplace %s\n", Version)
+        fmt.Printf("goreplace version %s\n", Version)
         os.Exit(0)
     }
 
+    // --help
     if (opts.ShowHelp) {
-		argparser.WriteHelp(os.Stdout)
-		os.Exit(1)
-	}
-
-	if (len(args) == 0) {
-	    err := errors.New("No files specified")
-	    logError(err)
-	    fmt.Println()
-		argparser.WriteHelp(os.Stdout)
-		os.Exit(1)
-	}
+        argparser.WriteHelp(os.Stdout)
+        os.Exit(1)
+    }
+
+    // missing any files
+    if (len(args) == 0) {
+        err := errors.New("No files specified")
+        logError(err)
+        fmt.Println()
+        argparser.WriteHelp(os.Stdout)
+        os.Exit(1)
+    }
 }
 
 func main() {
     var argparser = flags.NewParser(&opts, flags.PassDoubleDash)
-	args, err := argparser.Parse()
+    args, err := argparser.Parse()
 
-    if err != nil {
-        handleSpecialOptions(argparser, args)
+    handleSpecialCliOptions(argparser, args)
 
+    if err != nil {
         logError(err)
         fmt.Println()
         argparser.WriteHelp(os.Stdout)
         os.Exit(1)
     }
 
-	handleSpecialOptions(argparser, args)
-
-	buildSearchTerm()
+    buildSearchTerm()
 
     for i := range args {
         var file string
@@ -203,4 +219,4 @@ func main() {
     }
 
     os.Exit(0)
-}
+}