github.com/csfrancis/docker@v1.8.0-rc2/builder/bflag.go (about)

     1  package builder
     2  
     3  import (
     4  	"fmt"
     5  	"strings"
     6  )
     7  
     8  // FlagType is the type of the build flag
     9  type FlagType int
    10  
    11  const (
    12  	boolType FlagType = iota
    13  	stringType
    14  )
    15  
    16  // BFlags contains all flags information for the builder
    17  type BFlags struct {
    18  	Args  []string // actual flags/args from cmd line
    19  	flags map[string]*Flag
    20  	used  map[string]*Flag
    21  	Err   error
    22  }
    23  
    24  // Flag contains all information for a flag
    25  type Flag struct {
    26  	bf       *BFlags
    27  	name     string
    28  	flagType FlagType
    29  	Value    string
    30  }
    31  
    32  // NewBFlags return the new BFlags struct
    33  func NewBFlags() *BFlags {
    34  	return &BFlags{
    35  		flags: make(map[string]*Flag),
    36  		used:  make(map[string]*Flag),
    37  	}
    38  }
    39  
    40  // AddBool adds a bool flag to BFlags
    41  func (bf *BFlags) AddBool(name string, def bool) *Flag {
    42  	flag := bf.addFlag(name, boolType)
    43  	if flag == nil {
    44  		return nil
    45  	}
    46  	if def {
    47  		flag.Value = "true"
    48  	} else {
    49  		flag.Value = "false"
    50  	}
    51  	return flag
    52  }
    53  
    54  // AddString adds a string flag to BFlags
    55  func (bf *BFlags) AddString(name string, def string) *Flag {
    56  	flag := bf.addFlag(name, stringType)
    57  	if flag == nil {
    58  		return nil
    59  	}
    60  	flag.Value = def
    61  	return flag
    62  }
    63  
    64  func (bf *BFlags) addFlag(name string, flagType FlagType) *Flag {
    65  	if _, ok := bf.flags[name]; ok {
    66  		bf.Err = fmt.Errorf("Duplicate flag defined: %s", name)
    67  		return nil
    68  	}
    69  
    70  	newFlag := &Flag{
    71  		bf:       bf,
    72  		name:     name,
    73  		flagType: flagType,
    74  	}
    75  	bf.flags[name] = newFlag
    76  
    77  	return newFlag
    78  }
    79  
    80  // IsUsed checks if the flag is used
    81  func (fl *Flag) IsUsed() bool {
    82  	if _, ok := fl.bf.used[fl.name]; ok {
    83  		return true
    84  	}
    85  	return false
    86  }
    87  
    88  // IsTrue checks if a bool flag is true
    89  func (fl *Flag) IsTrue() bool {
    90  	if fl.flagType != boolType {
    91  		// Should never get here
    92  		panic(fmt.Errorf("Trying to use IsTrue on a non-boolean: %s", fl.name))
    93  	}
    94  	return fl.Value == "true"
    95  }
    96  
    97  // Parse parses and checks if the BFlags is valid
    98  func (bf *BFlags) Parse() error {
    99  	// If there was an error while defining the possible flags
   100  	// go ahead and bubble it back up here since we didn't do it
   101  	// earlier in the processing
   102  	if bf.Err != nil {
   103  		return fmt.Errorf("Error setting up flags: %s", bf.Err)
   104  	}
   105  
   106  	for _, arg := range bf.Args {
   107  		if !strings.HasPrefix(arg, "--") {
   108  			return fmt.Errorf("Arg should start with -- : %s", arg)
   109  		}
   110  
   111  		if arg == "--" {
   112  			return nil
   113  		}
   114  
   115  		arg = arg[2:]
   116  		value := ""
   117  
   118  		index := strings.Index(arg, "=")
   119  		if index >= 0 {
   120  			value = arg[index+1:]
   121  			arg = arg[:index]
   122  		}
   123  
   124  		flag, ok := bf.flags[arg]
   125  		if !ok {
   126  			return fmt.Errorf("Unknown flag: %s", arg)
   127  		}
   128  
   129  		if _, ok = bf.used[arg]; ok {
   130  			return fmt.Errorf("Duplicate flag specified: %s", arg)
   131  		}
   132  
   133  		bf.used[arg] = flag
   134  
   135  		switch flag.flagType {
   136  		case boolType:
   137  			// value == "" is only ok if no "=" was specified
   138  			if index >= 0 && value == "" {
   139  				return fmt.Errorf("Missing a value on flag: %s", arg)
   140  			}
   141  
   142  			lower := strings.ToLower(value)
   143  			if lower == "" {
   144  				flag.Value = "true"
   145  			} else if lower == "true" || lower == "false" {
   146  				flag.Value = lower
   147  			} else {
   148  				return fmt.Errorf("Expecting boolean value for flag %s, not: %s", arg, value)
   149  			}
   150  
   151  		case stringType:
   152  			if index < 0 {
   153  				return fmt.Errorf("Missing a value on flag: %s", arg)
   154  			}
   155  			flag.Value = value
   156  
   157  		default:
   158  			panic(fmt.Errorf("No idea what kind of flag we have! Should never get here!"))
   159  		}
   160  
   161  	}
   162  
   163  	return nil
   164  }