Initial commit

cmd/step/main.go

@@ -0,0 +1,72 @@
+// Command step evaluates STEP files and prints the result to standard out.
+package main
+
+import "os"
+import "io"
+import "fmt"
+import "context"
+import "git.tebibyte.media/sashakoshka/step"
+import "git.tebibyte.media/sashakoshka/go-cli"
+import "git.tebibyte.media/sashakoshka/step/providers"
+
+func main () {
+	// TODO: add some kind of way to play an http request to a STEP file,
+	// and have it be executed as if the request actually happened.
+	// TODO: initialize plugins on startup and tear them down on finish
+
+	// parse command line arguments
+	flagMetadata := cli.NewFlag (
+		'm', "metadata",
+		"Print document metadata as front matter")
+	cmd := cli.New (
+		"Evaluate STEP files and print the result",
+		flagMetadata,
+		cli.NewHelp())
+	cmd.Syntax = "[OPTIONS]... FILE"
+	cmd.ParseOrExit(os.Args)
+	if len(cmd.Args) > 1 {
+		cmd.Usage()
+		os.Exit(2)
+	}
+
+	// set up the environment
+	environment := step.Environment { }
+	environment.FuncProviders = providers.All()
+	err := environment.Init(context.Background())
+	handleErr(cmd, err)
+
+	// load and execute the document
+	var document *step.Document
+	if len(cmd.Args) > 0 {
+		document, err = environment.Parse(cmd.Args[0])
+	} else {
+		document, err = environment.ParseReader(".", os.Stdin)
+	}
+	handleErr(cmd, err)
+	if flagMetadata.Value == "true" {
+		writeMetadata(os.Stdout, document)
+	}
+	err = document.Execute(os.Stdout, step.ExecutionData { })
+	handleErr(cmd, err)
+}
+
+func handleErr (cmd *cli.Cli, err error) {
+	if err != nil {
+		cmd.Errorln(err)
+		os.Exit(1)
+	}
+}
+
+func writeMetadata (output io.Writer, document *step.Document) {
+	fmt.Fprintln(output, "---")
+	if document.Author != "" {
+		fmt.Fprintf(output, "Author: %s\n", document.Author)
+	}
+	if document.Title != "" {
+		fmt.Fprintf(output, "Title: %s\n", document.Title)
+	}
+	if document.Extends != "" {
+		fmt.Fprintf(output, "Extends: %s\n", document.Extends)
+	}
+	fmt.Fprintln(output, "---")
+}