fmtstr

Documentation

Index

• type EventFormatString
  • func CompileEvent(in string) (*EventFormatString, error)
  • func MustCompileEvent(in string) *EventFormatString
  • func (fs *EventFormatString) Eval(out *bytes.Buffer, event common.MapStr) error
  • func (fs *EventFormatString) Fields() []string
  • func (fs *EventFormatString) IsConst() bool
  • func (fs *EventFormatString) NumFields() int
  • func (fs *EventFormatString) Run(event common.MapStr) (string, error)
  • func (fs *EventFormatString) RunBytes(event common.MapStr) ([]byte, error)
  • func (fs *EventFormatString) Unpack(v interface{}) error
• type FormatEvaler
• type StringElement
  • func (e StringElement) Eval(_ interface{}, out *bytes.Buffer) error
• type StringFormatter
  • func Compile(in string, vc VariableCompiler) (StringFormatter, error)
• type VariableCompiler
• type VariableOp

Types

type EventFormatString

type EventFormatString struct {
	// contains filtered or unexported fields
}

EventFormatString implements format string support on events of type common.MapStr.

The concrete event expansion requires the field name enclosed by brackets. For example: '%{[field.name]}'. Field names can be separated by points or multiple braces. This format `%{[field.name]}` is equivalent to `%{[field][name]}`.

Default values are given defined by the colon operator. For example: `%{[field.name]:default value}`.

func CompileEvent

func CompileEvent(in string) (*EventFormatString, error)

CompileEvent compiles an event format string into an runnable EventFormatString. Returns error if parsing or compilation fails.

func MustCompileEvent

func MustCompileEvent(in string) *EventFormatString

MustCompileEvent copmiles an event format string into an runnable EventFormatString. Generates a panic if compilation fails.

func (*EventFormatString) Eval

func (fs *EventFormatString) Eval(out *bytes.Buffer, event common.MapStr) error

Eval executes the format string, writing the resulting string into the provided output buffer. Returns error if execution or event field expansion fails.

func (*EventFormatString) Fields

func (fs *EventFormatString) Fields() []string

Fields returns list of unique event fields required by the format string.

func (*EventFormatString) IsConst

func (fs *EventFormatString) IsConst() bool

IsConst checks the format string always returning the same constant string

func (*EventFormatString) NumFields

func (fs *EventFormatString) NumFields() int

NumFields returns number of unique event fields used by the format string.

func (*EventFormatString) Run

func (fs *EventFormatString) Run(event common.MapStr) (string, error)

Run executes the format string returning a new expanded string or an error if execution or event field expansion fails.

func (*EventFormatString) RunBytes

func (fs *EventFormatString) RunBytes(event common.MapStr) ([]byte, error)

RunBytes executes the format string returning a new expanded string of type `[]byte` or an error if execution or event field expansion fails.

func (*EventFormatString) Unpack

func (fs *EventFormatString) Unpack(v interface{}) error

Unpack tries to initialize the EventFormatString from provided value (which must be a string). Unpack method satisfies go-ucfg.Unpacker interface required by common.Config, in order to use EventFormatString with `common.(*Config).Unpack()`.

type FormatEvaler

type FormatEvaler interface {
	// Eval will execute the format and writes the results into
	// the provided output buffer. Returns error on failure.
	Eval(ctx interface{}, out *bytes.Buffer) error
}

FormatEvaler evaluates some format.

type StringElement

type StringElement struct {
	// contains filtered or unexported fields
}

StringElement implements StringFormatter always returning a constant string.

func (StringElement) Eval

func (e StringElement) Eval(_ interface{}, out *bytes.Buffer) error

Eval write the string elements constant string value into output buffer.

type StringFormatter

type StringFormatter interface {
	FormatEvaler

	// Run execute the formatter returning the generated string.
	Run(ctx interface{}) (string, error)

	// IsConst returns true, if execution of formatter will always return the
	// same constant string.
	IsConst() bool
}

StringFormatter interface extends FormatEvaler adding support for querying formatter meta data.

func Compile

func Compile(in string, vc VariableCompiler) (StringFormatter, error)

Compile compiles an input format string into a StringFormatter. The variable compiler `vc` is invoked for every variable expansion found in the input format string. Returns error on parse failure or if variable compiler fails.

Variable expansion are enclosed in expansion braces `%{<expansion>}`. The `<expansion>` can contain additional parameters separated by ops introduced by collons ':'. For example the format string `%{value:v1:?v2}` will be parsed into variable expansion on `value` with variable ops `[(":", "v1"), (":?", "v2")]`. It's up to the variable compiler to interpret content and variable ops.

The back-slash character `\` acts as escape character.

type VariableCompiler

type VariableCompiler func(string, []VariableOp) (FormatEvaler, error)

VariableCompiler is used to compile a variable expansion into an FormatEvaler to be used with the format-string.

type VariableOp

type VariableOp struct {
	// contains filtered or unexported fields
}

VariableOp defines one expansion variable, including operator and parameter. variable operations are always introduced by a collon ':'. For example the format string %{x:p1:?p2} has 2 variable operations (":", "p1") and (":?", "p2"). It's up to concrete format string implementation to compile and interpret variable ops.