Merge branch 'feature/cat' into 'master'

Feature/cat

Initial implementation of cat. So far, this only parses from the command line. I'll add in parsing from input frames once we work out some pipe merging issues.

See merge request !3

cat.go

@@ -0,0 +1,6 @@
+package jsh
+
+type CatOutput struct {
+	Output string
+	Files  []string
+}

cat/main.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"jsh"
+)
+
+func catFiles(queue chan *jsh.JshFrame) {
+	// Get all of the non-flags. The rest were processed by the main function
+	fileNames := flag.Args()
+	for _, fileName := range fileNames {
+		file, err := ioutil.ReadFile(fileName)
+
+		var jshFrame jsh.JshFrame
+
+		// If there's an error, output an error frame to the queue and continue
+		if err != nil {
+			errText := make(map[string]string)
+			errText[fileName] = fmt.Sprintf("%s", err.Error())
+			jshFrame = jsh.JshFrame{"", errText}
+			queue <- &jshFrame
+			continue
+		}
+
+		// Put the file contents into a frame and send them to the output
+		output := jsh.CatOutput{}
+		output.Files = []string{fileName}
+		output.Output = string(file)
+		jshFrame = jsh.JshFrame{output, ""}
+		queue <- &jshFrame
+	}
+}
+
+func runJsonMode() {
+	queue := make(chan *jsh.JshFrame)
+	done := make(chan bool)
+	go jsh.OutputFrames(queue, done)
+	catFiles(queue)
+	close(queue)
+	<-done
+}
+
+func main() {
+	// TODO: Support more flags
+	jsonModePtr := flag.Bool("json", false, "whether to use json mode for input and output")
+	flag.Parse()
+
+	if !*jsonModePtr {
+		fmt.Printf("%s", jsh.FallbackWithArgs("cat", flag.Args()))
+	} else {
+		runJsonMode()
+	}
+}