added yml/json/toml support, --help flag, and example directory

Signed-off-by: Andrey Nering <andrey.nering@gmail.com>

cmd/task/task.go

@@ -1,9 +1,34 @@
 package main
 
 import (
+	"flag"
+	"fmt"
+
 	"github.com/go-task/task"
 )
 
 func main() {
+	flag.CommandLine.Usage = func() {
+		fmt.Println(`
+task [target1 target2 ...]: Runs commands under targets like make.
+
+Example: 'task hello' with the following 'Taskfile.json' file will generate
+an 'output.txt' file.
+'''
+{
+  "hello": {
+    "cmds": [
+      "echo \"I am going to write a file named 'output.txt' now.\"",
+      "echo \"hello\" > output.txt"
+    ],
+    "generates": [
+      "output.txt"
+    ]
+  }
+}
+'''
+`)
+	}
+	flag.Parse()
 	task.Run()
 }

example/Taskfile.json

@@ -0,0 +1,11 @@
+{
+  "hello": {
+    "cmds": [
+      "echo \"I am going to write a file named 'output.txt' now.\"",
+      "echo \"hello\" > output.txt"
+    ],
+    "generates": [
+      "output.txt"
+    ]
+  }
+}

example/Taskfile.yml

@@ -0,0 +1,6 @@
+hello:
+  cmds:
+    - echo "I am going to write a file named 'output.txt' now."
+    - echo "hello" > output.txt
+  generates:
+    - output.txt

task.go

@@ -1,18 +1,21 @@
 package task
 
 import (
+	"encoding/json"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
 
+	"github.com/BurntSushi/toml"
 	"gopkg.in/yaml.v2"
 )
 
 var (
 	// TaskFilePath is the default Taskfile
-	TaskFilePath = "Taskfile.yml"
+	TaskFilePath = "Taskfile"
 	// ShExists is true if Bash was found
 	ShExists bool
 	// ShPath constains the Bash path if found
@@ -65,15 +68,9 @@ func Run() {
 		log.Fatal("No argument given")
 	}
 
-	file, err := ioutil.ReadFile(TaskFilePath)
+	var err error
+	Tasks, err = readTaskfile()
 	if err != nil {
-		if os.IsNotExist(err) {
-			log.Fatal("Taskfile.yml not found")
-		}
-		log.Fatal(err)
-	}
-
-	if err = yaml.Unmarshal(file, &Tasks); err != nil {
 		log.Fatal(err)
 	}
 
@@ -142,3 +139,19 @@ func runCommand(c string) error {
 	}
 	return nil
 }
+
+func readTaskfile() (tasks map[string]*Task, err error) {
+	if b, err := ioutil.ReadFile(TaskFilePath + ".yml"); err == nil {
+		return tasks, yaml.Unmarshal(b, &tasks)
+	}
+	if b, err := ioutil.ReadFile(TaskFilePath + ".json"); err == nil {
+		return tasks, json.Unmarshal(b, &tasks)
+	}
+	if b, err := ioutil.ReadFile(TaskFilePath + ".toml"); err == nil {
+		return tasks, toml.Unmarshal(b, &tasks)
+	}
+	return nil, ErrNoTaskFile
+}
+
+// ErrNoTaskFile is returns when the program can not find a proper TaskFile
+var ErrNoTaskFile = errors.New("no task file found (is it named '" + TaskFilePath + "'?)")