feat: Add flag for turning off colors in TTY printing (#214)

cmd/scip/print.go

@@ -3,6 +3,8 @@ package main
 import (
 	"io"
 	"math"
+	"os"
+	"strings"
 
 	"github.com/k0kubun/pp/v3"
 	"github.com/urfave/cli/v2"
@@ -12,31 +14,49 @@ import (
 )
 
 func printCommand() cli.Command {
-	var json bool
+	var json, colorOutput bool
 	snapshot := cli.Command{
 		Name:  "print",
-		Usage: "Print a SCIP index in a human-readable format for debugging",
-		Description: `WARNING: The output may change over time.
-Do not rely on the output of this command in scripts`,
+		Usage: "Print a SCIP index for debugging",
+		Description: `WARNING: The TTY output may change over time.
+Do not rely on non-JSON output in scripts`,
 		Flags: []cli.Flag{
 			&cli.BoolFlag{
 				Name:        "json",
 				Usage:       "Output in JSON format",
 				Destination: &json,
 			},
+			&cli.BoolFlag{
+				Name:        "color",
+				Usage:       "Enable color output for TTY (no effect for JSON)",
+				Destination: &colorOutput,
+				Value:       true,
+				DefaultText: "true",
+			},
 		},
 		Action: func(c *cli.Context) error {
 			indexPath := c.Args().Get(0)
 			if indexPath == "" {
 				return errors.New("missing argument for path to SCIP index")
 			}
-			return printMain(indexPath, json, c.App.Writer)
+			// Following https://no-color.org/
+			if val, found := os.LookupEnv("NO_COLOR"); found && val != "" {
+				switch strings.ToLower(val) {
+				case "":
+					break
+				case "0", "false", "off":
+					colorOutput = false
+				default:
+					colorOutput = true
+				}
+			}
+			return printMain(indexPath, colorOutput, json, c.App.Writer)
 		},
 	}
 	return snapshot
 }
 
-func printMain(indexPath string, json bool, out io.Writer) error {
+func printMain(indexPath string, colorOutput bool, json bool, out io.Writer) error {
 	index, err := readFromOption(indexPath)
 	if err != nil {
 		return err
@@ -51,6 +71,7 @@ func printMain(indexPath string, json bool, out io.Writer) error {
 		return err
 	} else {
 		prettyPrinter := pp.New()
+		prettyPrinter.SetColoringEnabled(colorOutput)
 		prettyPrinter.SetExportedOnly(true)
 		prettyPrinter.SetOutput(out)
 		_, err = prettyPrinter.Print(index)

docs/CLI.md

@@ -28,7 +28,7 @@ DESCRIPTION:
 COMMANDS:
    convert   Convert a SCIP index to an LSIF index
    lint      Flag potential issues with a SCIP index
-   print     Print a SCIP index in a human-readable format for debugging
+   print     Print a SCIP index for debugging
    snapshot  Generate snapshot files for golden testing
    stats     Output useful statistics about a SCIP index
    help, h   Shows a list of commands or help for one command
@@ -74,17 +74,19 @@ DESCRIPTION:
 
 ```
 NAME:
-   scip print - Print a SCIP index in a human-readable format for debugging
+   scip print - Print a SCIP index for debugging
 
 USAGE:
    scip print [command options] [arguments...]
 
 DESCRIPTION:
-   WARNING: The output may change over time.
-   Do not rely on the output of this command in scripts
+   WARNING: The TTY output may change over time.
+   Do not rely on non-JSON output in scripts
 
 OPTIONS:
    --json      Output in JSON format (default: false)
+   --color     Enable color output for TTY (no effect for JSON) (default: true)
+   --help, -h  show help
 ```
 
 ## `scip snapshot`