Update gomod and vendor

vendor/github.com/moby/buildkit/frontend/dockerfile/instructions/bflag.go

@@ -0,0 +1,200 @@
+package instructions
+
+import (
+	"fmt"
+	"strings"
+)
+
+// FlagType is the type of the build flag
+type FlagType int
+
+const (
+	boolType FlagType = iota
+	stringType
+	stringsType
+)
+
+// BFlags contains all flags information for the builder
+type BFlags struct {
+	Args  []string // actual flags/args from cmd line
+	flags map[string]*Flag
+	used  map[string]*Flag
+	Err   error
+}
+
+// Flag contains all information for a flag
+type Flag struct {
+	bf           *BFlags
+	name         string
+	flagType     FlagType
+	Value        string
+	StringValues []string
+}
+
+// NewBFlags returns the new BFlags struct
+func NewBFlags() *BFlags {
+	return &BFlags{
+		flags: make(map[string]*Flag),
+		used:  make(map[string]*Flag),
+	}
+}
+
+// NewBFlagsWithArgs returns the new BFlags struct with Args set to args
+func NewBFlagsWithArgs(args []string) *BFlags {
+	flags := NewBFlags()
+	flags.Args = args
+	return flags
+}
+
+// AddBool adds a bool flag to BFlags
+// Note, any error will be generated when Parse() is called (see Parse).
+func (bf *BFlags) AddBool(name string, def bool) *Flag {
+	flag := bf.addFlag(name, boolType)
+	if flag == nil {
+		return nil
+	}
+	if def {
+		flag.Value = "true"
+	} else {
+		flag.Value = "false"
+	}
+	return flag
+}
+
+// AddString adds a string flag to BFlags
+// Note, any error will be generated when Parse() is called (see Parse).
+func (bf *BFlags) AddString(name string, def string) *Flag {
+	flag := bf.addFlag(name, stringType)
+	if flag == nil {
+		return nil
+	}
+	flag.Value = def
+	return flag
+}
+
+// AddStrings adds a string flag to BFlags that can match multiple values
+func (bf *BFlags) AddStrings(name string) *Flag {
+	flag := bf.addFlag(name, stringsType)
+	if flag == nil {
+		return nil
+	}
+	return flag
+}
+
+// addFlag is a generic func used by the other AddXXX() func
+// to add a new flag to the BFlags struct.
+// Note, any error will be generated when Parse() is called (see Parse).
+func (bf *BFlags) addFlag(name string, flagType FlagType) *Flag {
+	if _, ok := bf.flags[name]; ok {
+		bf.Err = fmt.Errorf("Duplicate flag defined: %s", name)
+		return nil
+	}
+
+	newFlag := &Flag{
+		bf:       bf,
+		name:     name,
+		flagType: flagType,
+	}
+	bf.flags[name] = newFlag
+
+	return newFlag
+}
+
+// IsUsed checks if the flag is used
+func (fl *Flag) IsUsed() bool {
+	if _, ok := fl.bf.used[fl.name]; ok {
+		return true
+	}
+	return false
+}
+
+// IsTrue checks if a bool flag is true
+func (fl *Flag) IsTrue() bool {
+	if fl.flagType != boolType {
+		// Should never get here
+		panic(fmt.Errorf("Trying to use IsTrue on a non-boolean: %s", fl.name))
+	}
+	return fl.Value == "true"
+}
+
+// Parse parses and checks if the BFlags is valid.
+// Any error noticed during the AddXXX() funcs will be generated/returned
+// here.  We do this because an error during AddXXX() is more like a
+// compile time error so it doesn't matter too much when we stop our
+// processing as long as we do stop it, so this allows the code
+// around AddXXX() to be just:
+//     defFlag := AddString("description", "")
+// w/o needing to add an if-statement around each one.
+func (bf *BFlags) Parse() error {
+	// If there was an error while defining the possible flags
+	// go ahead and bubble it back up here since we didn't do it
+	// earlier in the processing
+	if bf.Err != nil {
+		return fmt.Errorf("Error setting up flags: %s", bf.Err)
+	}
+
+	for _, arg := range bf.Args {
+		if !strings.HasPrefix(arg, "--") {
+			return fmt.Errorf("Arg should start with -- : %s", arg)
+		}
+
+		if arg == "--" {
+			return nil
+		}
+
+		arg = arg[2:]
+		value := ""
+
+		index := strings.Index(arg, "=")
+		if index >= 0 {
+			value = arg[index+1:]
+			arg = arg[:index]
+		}
+
+		flag, ok := bf.flags[arg]
+		if !ok {
+			return fmt.Errorf("Unknown flag: %s", arg)
+		}
+
+		if _, ok = bf.used[arg]; ok && flag.flagType != stringsType {
+			return fmt.Errorf("Duplicate flag specified: %s", arg)
+		}
+
+		bf.used[arg] = flag
+
+		switch flag.flagType {
+		case boolType:
+			// value == "" is only ok if no "=" was specified
+			if index >= 0 && value == "" {
+				return fmt.Errorf("Missing a value on flag: %s", arg)
+			}
+
+			lower := strings.ToLower(value)
+			if lower == "" {
+				flag.Value = "true"
+			} else if lower == "true" || lower == "false" {
+				flag.Value = lower
+			} else {
+				return fmt.Errorf("Expecting boolean value for flag %s, not: %s", arg, value)
+			}
+
+		case stringType:
+			if index < 0 {
+				return fmt.Errorf("Missing a value on flag: %s", arg)
+			}
+			flag.Value = value
+
+		case stringsType:
+			if index < 0 {
+				return fmt.Errorf("Missing a value on flag: %s", arg)
+			}
+			flag.StringValues = append(flag.StringValues, value)
+
+		default:
+			panic("No idea what kind of flag we have! Should never get here!")
+		}
+
+	}
+
+	return nil
+}