Add --format option to skopeo inspect

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

vendor/github.com/containers/common/pkg/report/template.go

@@ -0,0 +1,115 @@
+package report
+
+import (
+	"reflect"
+	"strings"
+	"text/template"
+
+	"github.com/containers/common/pkg/report/camelcase"
+)
+
+// Template embeds template.Template to add functionality to methods
+type Template struct {
+	*template.Template
+	isTable bool
+}
+
+// FuncMap is aliased from template.FuncMap
+type FuncMap template.FuncMap
+
+// tableReplacer will remove 'table ' prefix and clean up tabs
+var tableReplacer = strings.NewReplacer(
+	"table ", "",
+	`\t`, "\t",
+	`\n`, "\n",
+	" ", "\t",
+)
+
+// escapedReplacer will clean up escaped characters from CLI
+var escapedReplacer = strings.NewReplacer(
+	`\t`, "\t",
+	`\n`, "\n",
+)
+
+// NormalizeFormat reads given go template format provided by CLI and munges it into what we need
+func NormalizeFormat(format string) string {
+	var f string
+	// two replacers used so we only remove the prefix keyword `table`
+	if strings.HasPrefix(format, "table ") {
+		f = tableReplacer.Replace(format)
+	} else {
+		f = escapedReplacer.Replace(format)
+	}
+
+	if !strings.HasSuffix(f, "\n") {
+		f += "\n"
+	}
+	return f
+}
+
+// Headers queries the interface for field names.
+// Array of map is returned to support range templates
+// Note: unexported fields can be supported by adding field to overrides
+// Note: It is left to the developer to write out said headers
+//       Podman commands use the general rules of:
+//       1) unchanged --format includes headers
+//       2) --format '{{.ID}"        # no headers
+//       3) --format 'table {{.ID}}' # includes headers
+func Headers(object interface{}, overrides map[string]string) []map[string]string {
+	value := reflect.ValueOf(object)
+	if value.Kind() == reflect.Ptr {
+		value = value.Elem()
+	}
+
+	// Column header will be field name upper-cased.
+	headers := make(map[string]string, value.NumField())
+	for i := 0; i < value.Type().NumField(); i++ {
+		field := value.Type().Field(i)
+		// Recurse to find field names from promoted structs
+		if field.Type.Kind() == reflect.Struct && field.Anonymous {
+			h := Headers(reflect.New(field.Type).Interface(), nil)
+			for k, v := range h[0] {
+				headers[k] = v
+			}
+			continue
+		}
+		name := strings.Join(camelcase.Split(field.Name), " ")
+		headers[field.Name] = strings.ToUpper(name)
+	}
+
+	if len(overrides) > 0 {
+		// Override column header as provided
+		for k, v := range overrides {
+			headers[k] = strings.ToUpper(v)
+		}
+	}
+	return []map[string]string{headers}
+}
+
+// NewTemplate creates a new template object
+func NewTemplate(name string) *Template {
+	return &Template{template.New(name), false}
+}
+
+// Parse parses text as a template body for t
+func (t *Template) Parse(text string) (*Template, error) {
+	if strings.HasPrefix(text, "table ") {
+		t.isTable = true
+		text = "{{range .}}" + NormalizeFormat(text) + "{{end}}"
+	} else {
+		text = NormalizeFormat(text)
+	}
+
+	tt, err := t.Template.Parse(text)
+	return &Template{tt, t.isTable}, err
+}
+
+// Funcs adds the elements of the argument map to the template's function map
+func (t *Template) Funcs(funcMap FuncMap) *Template {
+	return &Template{t.Template.Funcs(template.FuncMap(funcMap)), t.isTable}
+}
+
+// IsTable returns true if format string defines a "table"
+func (t *Template) IsTable() bool {
+	return t.isTable
+}