Add self-contained gometalinter build tooling.

tools/vendor/github.com/alexflint/go-arg/usage.go

@@ -0,0 +1,148 @@
+package arg
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"reflect"
+	"strings"
+)
+
+// the width of the left column
+const colWidth = 25
+
+// Fail prints usage information to stderr and exits with non-zero status
+func (p *Parser) Fail(msg string) {
+	p.WriteUsage(os.Stderr)
+	fmt.Fprintln(os.Stderr, "error:", msg)
+	os.Exit(-1)
+}
+
+// WriteUsage writes usage information to the given writer
+func (p *Parser) WriteUsage(w io.Writer) {
+	var positionals, options []*spec
+	for _, spec := range p.spec {
+		if spec.positional {
+			positionals = append(positionals, spec)
+		} else {
+			options = append(options, spec)
+		}
+	}
+
+	if p.version != "" {
+		fmt.Fprintln(w, p.version)
+	}
+
+	fmt.Fprintf(w, "Usage: %s", p.config.Program)
+
+	// write the option component of the usage message
+	for _, spec := range options {
+		// prefix with a space
+		fmt.Fprint(w, " ")
+		if !spec.required {
+			fmt.Fprint(w, "[")
+		}
+		fmt.Fprint(w, synopsis(spec, "--"+spec.long))
+		if !spec.required {
+			fmt.Fprint(w, "]")
+		}
+	}
+
+	// write the positional component of the usage message
+	for _, spec := range positionals {
+		// prefix with a space
+		fmt.Fprint(w, " ")
+		up := strings.ToUpper(spec.long)
+		if spec.multiple {
+			if !spec.required {
+				fmt.Fprint(w, "[")
+			}
+			fmt.Fprintf(w, "%s [%s ...]", up, up)
+			if !spec.required {
+				fmt.Fprint(w, "]")
+			}
+		} else {
+			fmt.Fprint(w, up)
+		}
+	}
+	fmt.Fprint(w, "\n")
+}
+
+// WriteHelp writes the usage string followed by the full help string for each option
+func (p *Parser) WriteHelp(w io.Writer) {
+	var positionals, options []*spec
+	for _, spec := range p.spec {
+		if spec.positional {
+			positionals = append(positionals, spec)
+		} else {
+			options = append(options, spec)
+		}
+	}
+
+	if p.description != "" {
+		fmt.Fprintln(w, p.description)
+	}
+	p.WriteUsage(w)
+
+	// write the list of positionals
+	if len(positionals) > 0 {
+		fmt.Fprint(w, "\nPositional arguments:\n")
+		for _, spec := range positionals {
+			left := "  " + strings.ToUpper(spec.long)
+			fmt.Fprint(w, left)
+			if spec.help != "" {
+				if len(left)+2 < colWidth {
+					fmt.Fprint(w, strings.Repeat(" ", colWidth-len(left)))
+				} else {
+					fmt.Fprint(w, "\n"+strings.Repeat(" ", colWidth))
+				}
+				fmt.Fprint(w, spec.help)
+			}
+			fmt.Fprint(w, "\n")
+		}
+	}
+
+	// write the list of options
+	fmt.Fprint(w, "\nOptions:\n")
+	for _, spec := range options {
+		printOption(w, spec)
+	}
+
+	// write the list of built in options
+	printOption(w, &spec{boolean: true, long: "help", short: "h", help: "display this help and exit"})
+	if p.version != "" {
+		printOption(w, &spec{boolean: true, long: "version", help: "display version and exit"})
+	}
+}
+
+func printOption(w io.Writer, spec *spec) {
+	left := "  " + synopsis(spec, "--"+spec.long)
+	if spec.short != "" {
+		left += ", " + synopsis(spec, "-"+spec.short)
+	}
+	fmt.Fprint(w, left)
+	if spec.help != "" {
+		if len(left)+2 < colWidth {
+			fmt.Fprint(w, strings.Repeat(" ", colWidth-len(left)))
+		} else {
+			fmt.Fprint(w, "\n"+strings.Repeat(" ", colWidth))
+		}
+		fmt.Fprint(w, spec.help)
+	}
+	// If spec.dest is not the zero value then a default value has been added.
+	v := spec.dest
+	if v.IsValid() {
+		z := reflect.Zero(v.Type())
+		if (v.Type().Comparable() && z.Type().Comparable() && v.Interface() != z.Interface()) || v.Kind() == reflect.Slice && !v.IsNil() {
+			fmt.Fprintf(w, " [default: %v]", v)
+		}
+	}
+	fmt.Fprint(w, "\n")
+}
+
+func synopsis(spec *spec, form string) string {
+	if spec.boolean {
+		return form
+	}
+	return form + " " + strings.ToUpper(spec.long)
+}