From bcf78eff303c4bfcb53e95d3f50040f124664308 Mon Sep 17 00:00:00 2001
From: Syuparn <s.hello.spagetti@gmail.com>
Date: Mon, 22 Feb 2021 10:47:39 +0900
Subject: [PATCH] add -v option

---
 main.go    | 14 ++++++++++----
 version.go | 25 +++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 4 deletions(-)
 create mode 100644 version.go

diff --git a/main.go b/main.go
index 114c3a0..2754be5 100644
--- a/main.go
+++ b/main.go
@@ -12,15 +12,21 @@ import (
 )
 
 var (
-	fileName   = flag.String("f", "", "use template file")
-	runsREPL   = flag.Bool("i", false, "run interactive REPL instead")
-	leftDelim  = flag.String("ldelim", "{{", "specify left deliminater")
-	rightDelim = flag.String("rdelim", "}}", "specify right deliminater")
+	fileName     = flag.String("f", "", "use template file")
+	runsREPL     = flag.Bool("i", false, "run interactive REPL instead")
+	showsVersion = flag.Bool("v", false, "show version")
+	leftDelim    = flag.String("ldelim", "{{", "specify left deliminater")
+	rightDelim   = flag.String("rdelim", "}}", "specify right deliminater")
 )
 
 func main() {
 	flag.Parse()
 
+	if *showsVersion {
+		fmt.Println(versionStr())
+		return
+	}
+
 	tmpl := newTemplate(*leftDelim, *rightDelim)
 
 	if *runsREPL {
diff --git a/version.go b/version.go
new file mode 100644
index 0000000..d6ecc8b
--- /dev/null
+++ b/version.go
@@ -0,0 +1,25 @@
+package main
+
+import (
+	"runtime/debug"
+)
+
+const defaultVersion = "development"
+
+var version = ""
+
+func versionStr() string {
+	// 1. if version is set (by goreleaser for example), show it
+	if version != "" {
+		return version
+	}
+
+	// 2. if runtime version is set (by go get for example), show it
+	info, ok := debug.ReadBuildInfo()
+	if ok {
+		return info.Main.Version
+	}
+
+	// 3. show default version
+	return defaultVersion
+}