Documentation
¶
Index ¶
- Constants
- func DumpGrammar(ctx *Context)
- func ShowHelp(c *Context)
- type Context
- func (c *Context) Boolean(name string) bool
- func (c *Context) FindGlobal() *Context
- func (c *Context) GetParameter(i int) string
- func (c *Context) GetParameterCount() int
- func (c *Context) Integer(name string) (int, bool)
- func (c *Context) Keyword(name string) (int, bool)
- func (c *Context) Parse() error
- func (c *Context) ResolveEnvironmentVariables() error
- func (c *Context) String(name string) (string, bool)
- func (c *Context) StringList(name string) ([]string, bool)
- func (c *Context) WasFound(name string) bool
- type Error
- type ExitError
- type Option
Constants ¶
const ( ExitSuccess = 0 ExitGeneralError = 1 ExitUsageError = 2 )
Exit codes passed to the operating system.
const ( CLIErrorPrefix = "during command line processing" InvalidBooleanValueError = "option --%s invalid boolean value: %s" InvalidIntegerError = "option --%s invalid integer value: %s" InvalidKeywordError = "option --%s has no such keyword: %s" RequiredNotFoundError = "required option %s not found" TooManyParametersError = "too many parameters on command line" UnexpectedParametersError = "unexpected parameters or invalid subcommand" UnknownOptionError = "unknown option: %s" WrongParameterCountError = "incorrect number of parameters" )
CLI error message strings.
const ( // StringType accepts a string (in quotes if it contains spaces or punctuation). StringType = 1 // IntType accepts a signed integer value. IntType = 2 // BooleanType is true if present, or false if not present. BooleanType = 3 // BooleanValueType is representation of the boolean value (true/false). BooleanValueType = 4 // Subcommand specifies that the LongName is a command name, and parsing continues with the SubGrammar. Subcommand = 6 // StringListType is a string value or a list of string values, separated by commas and enclosed in quotes. StringListType = 7 // ParameterType is a parameter from the command line. They should be declared in order. ParameterType = 8 // UUIDType defines a value that must be a valid (parsable) UUID, though the value is stored // as a string datum. UUIDType = 9 // KeywordType is a string that must be from an approved list of keyword values. KeywordType = 10 )
Variables ¶
This section is empty.
Functions ¶
func DumpGrammar ¶
func DumpGrammar(ctx *Context)
func ShowHelp ¶
func ShowHelp(c *Context)
ShowHelp displays help text for the grammar, using a standardized format. The help shows subcommands as well as options, including value type cues. The output is automatically directed to the stdout console output.
This function uses the tables package to create uniform columns of output.
Types ¶
type Context ¶
type Context struct {
AppName string
MainProgram string
Description string
Copyright string
Version string
Command string
ParameterDescription string
Grammar []Option
Args []string
Parameters []string
Parent *Context
Action func(c *Context) error
ParameterCount int
ExpectedParameterCount int
}
Context is a simple array of Option types, and is used to express a grammar at a given level (root, subcommand, etc.).
func (*Context) Boolean ¶
Boolean returns the value of a named boolean. If the boolean option was found during processing, this routine returns true. Otherwise it returns false.
func (*Context) FindGlobal ¶
FindGlobal locates the top-most context structure in the chain of nested contexts. If our tree has no parent, we are the global grammar. Otherwise, ask our parent...
func (*Context) GetParameter ¶
GetParameter returns the ith parameter string parsed, or an empty string if not found.
func (*Context) GetParameterCount ¶
GetParameterCount returns the number of parameters processed.
func (*Context) Integer ¶
Integer returns the value of a named integer from the parsed grammar, or a zero if not found. The boolean return value confirms if the value was specified on the command line.
func (*Context) Keyword ¶
Keyword returns the value of a named string parameter from the parsed grammar. The result is the ordinal position (zero-based) on the keyword from the list. If the value is not in the list, it returns -1.
func (*Context) Parse ¶
Parse processes the grammar associated with the current context, using the []string array of arguments for that context.
Unrecognized options or subcommands, as well as invalid values are reported as an error. If there is an action routine associated with an option or a subcommand, that action is executed.
func (*Context) ResolveEnvironmentVariables ¶
ResolveEnvironmentVariables searches the grammar tree backwards looking for options that can be specified by an environment variable, and marking those found as needed. This is done after the command line options are processed, to provide defaults for un-specified options.
func (*Context) String ¶
String returns the value of a named string parameter from the parsed grammar, or an empty string if not found. The second return value indicates if the value was explicitly specified. This is used to differentiate between "not specified" and "specified as empty".
func (*Context) StringList ¶
StringList returns the array of strings that are the value of the named item. If the item is not found, an empty array is returned. The second value in the result indicates of the option was explicitly specified in the command line.
type Error ¶
type Error struct {
// contains filtered or unexported fields
}
Wrapper for CLI errors.
func NewCLIError ¶
NewCLIError generates a new CLIError object using the message string and optional values that are formatted using the message string.
type ExitError ¶
ExitError is a wrapped error code structure used to return a message and a desired operating system exit value.
func NewExitError ¶
NewExitError constructs an ExitError.
type Option ¶
type Option struct {
ShortName string
LongName string
Description string
ParameterDescription string
EnvironmentVariable string
Aliases []string
Keywords []string
Value interface{}
Action func(c *Context) error
OptionType int
ParametersExpected int
Found bool
Required bool
Private bool
}
Option defines the structure of each option that can be parsed.
Source Files