selector

package
v1.20240719.1 Latest Latest
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 Go to latest Published: Jul 19, 2024 License: MIT Imports: 6 Imported by: 5

Documentation

Overview

Package selector is a high performance selector parsing library, tightly coupled to the functionality of selectors found in Kubernetes.

Index

Constants

View Source 
const (
	// At is a common rune.
	At = rune('@')
	// Colon is a common rune.
	Colon = rune(':')
	// Dash is a common rune.
	Dash = rune('-')
	// Underscore  is a common rune.
	Underscore = rune('_')
	// Dot is a common rune.
	Dot = rune('.')
	// ForwardSlash is a common rune.
	ForwardSlash = rune('/')
	// BackSlash is a common rune.
	BackSlash = rune('\\')
	// BackTick is a common rune.
	BackTick = rune('`')
	// Bang is a common rune.
	Bang = rune('!')
	// Comma is a common rune.
	Comma = rune(',')
	// OpenBracket is a common rune.
	OpenBracket = rune('[')
	// OpenParens is a common rune.
	OpenParens = rune('(')
	// OpenCurly is a common rune.
	OpenCurly = rune('{')
	// CloseBracket is a common rune.
	CloseBracket = rune(']')
	// CloseParens is a common rune.
	CloseParens = rune(')')
	// Equal is a common rune.
	Equal = rune('=')
	// Space is a common rune.
	Space = rune(' ')
	// Tab is a common rune.
	Tab = rune('\t')
	// Tilde is a common rune.
	Tilde = rune('~')
	// CarriageReturn is a common rune.
	CarriageReturn = rune('\r')
	// NewLine is a common rune.
	NewLine = rune('\n')
)
View Source 
const (
	// OpEquals is an operator.
	OpEquals = "="
	// OpDoubleEquals is an operator.
	OpDoubleEquals = "=="
	// OpNotEquals is an operator.
	OpNotEquals = "!="
	// OpIn is an operator.
	OpIn = "in"
	// OpNotIn is an operator.
	OpNotIn = "notin"
)

Variables

View Source 
var (
	// MaxLabelKeyTotalLen is the maximum total key length.
	MaxLabelKeyTotalLen = MaxLabelKeyDNSSubdomainLen + MaxLabelKeyLen + 1
)

Functions

func CheckDNS added in v1.20210103.1 

func CheckDNS(value string) (err error)

CheckDNS returns if a given value is a conformant DNS_SUBDOMAIN.

See: https://www.ietf.org/rfc/rfc952.txt and https://www.ietf.org/rfc/rfc1123.txt (2.1) for more information.

Specifically a DNS_SUBDOMAIN must: - Be constituted of ([a-z0-9\-\.]) - It must start and end with ([a-z0-9]) - it must be less than 254 characters in length - Characters ('.', '-') cannot repeat

func CheckKey 

func CheckKey(key string) (err error)

CheckKey validates a key.

func CheckLabels 

func CheckLabels(labels Labels) (err error)

CheckLabels validates all the keys and values for the label set.

func CheckName added in v1.20211016.2 

func CheckName(value string) (err error)

CheckName checks the characters in a name but does not validate the length.

func CheckValue 

func CheckValue(value string) error

CheckValue returns if the value is valid.

func SkipValidation 

func SkipValidation(p *Parser)

SkipValidation is an option to skip checking the values of selector expressions.

Types

type And 

type And []Selector

And is a combination selector.

func (And) Matches 

func (a And) Matches(labels Labels) bool

Matches returns if both A and B match the labels.

func (And) String 

func (a And) String() string

And returns a string representation for the selector.

func (And) Validate 

func (a And) Validate() (err error)

Validate validates all the selectors in the clause.

type Any 

type Any struct{}

Any matches everything

func (Any) Matches 

func (a Any) Matches(labels Labels) bool

Matches returns true

func (Any) String 

func (a Any) String() string

String returns a string representation of the selector

func (Any) Validate 

func (a Any) Validate() (err error)

Validate validates the selector

type Equals 

type Equals struct {
	Key, Value string
}

Equals returns if a key strictly equals a value.

func (Equals) Matches 

func (e Equals) Matches(labels Labels) bool

Matches returns the selector result.

func (Equals) String 

func (e Equals) String() string

String returns the string representation of the selector.

func (Equals) Validate 

func (e Equals) Validate() (err error)

Validate validates the selector.

type Error 

type Error string

Error is a hard alias to string. 

const (
	// ErrInvalidOperator is returned if the operator is invalid.
	ErrInvalidOperator Error = "invalid operator"
	// ErrInvalidSelector is returned if there is a structural issue with the selector.
	ErrInvalidSelector Error = "invalid selector"
	// ErrLabelKeyEmpty indicates a key is empty.
	ErrLabelKeyEmpty Error = "label key empty"
	// ErrLabelKeyTooLong indicates a key is too long.
	ErrLabelKeyTooLong Error = "label key too long"
	// ErrLabelKeyDNSSubdomainEmpty indicates a key's "dns" subdomain is empty, i.e. it is in the form `/foo`
	ErrLabelKeyDNSSubdomainEmpty Error = "label key dns subdomain empty"
	// ErrLabelKeyDNSSubdomainTooLong indicates a key's "dns" subdomain is too long.
	ErrLabelKeyDNSSubdomainTooLong Error = "label key dns subdomain too long; must be less than 253 characters"
	// ErrLabelValueTooLong indicates a value is too long.
	ErrLabelValueTooLong Error = "label value too long; must be less than 63 characters"
	// ErrLabelInvalidCharacter indicates a value contains characters
	ErrLabelInvalidCharacter Error = `label contains invalid characters, regex used: ([A-Za-z0-9_-.])`
	// ErrLabelKeyInvalidDNSSubdomain indicates a key contains characters
	ErrLabelKeyInvalidDNSSubdomain Error = `label key dns subdomain contains invalid dns characters, regex used: ([a-z0-9-.])`

	// MaxLabelKeyDNSSubdomainLen is the maximum dns prefix length.
	MaxLabelKeyDNSSubdomainLen = 253
	// MaxLabelKeyLen is the maximum key length.
	MaxLabelKeyLen = 63
	// MaxLabelValueLen is the maximum value length.
	MaxLabelValueLen = 63
)

func (Error) Error 

func (e Error) Error() string

Error implements `error`

func (Error) MarshalJSON 

func (e Error) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.

type HasKey 

type HasKey string

HasKey returns if a label set has a given key.

func (HasKey) Matches 

func (hk HasKey) Matches(labels Labels) bool

Matches returns the selector result.

func (HasKey) String 

func (hk HasKey) String() string

String returns a string representation of the selector.

func (HasKey) Validate 

func (hk HasKey) Validate() (err error)

Validate validates the selector.

type In 

type In struct {
	Key    string
	Values []string
}

In returns if a key matches a set of values.

func (In) Matches 

func (i In) Matches(labels Labels) bool

Matches returns the selector result.

func (In) String 

func (i In) String() string

String returns a string representation of the selector.

func (In) Validate 

func (i In) Validate() (err error)

Validate validates the selector.

type Labels 

type Labels = map[string]string

Labels is an alias for map[string]string

type NotEquals 

type NotEquals struct {
	Key, Value string
}

NotEquals returns if a key strictly equals a value.

func (NotEquals) Matches 

func (ne NotEquals) Matches(labels Labels) bool

Matches returns the selector result.

func (NotEquals) String 

func (ne NotEquals) String() string

String returns a string representation of the selector.

func (NotEquals) Validate 

func (ne NotEquals) Validate() (err error)

Validate validates the selector.

type NotHasKey 

type NotHasKey string

NotHasKey returns if a label set does not have a given key.

func (NotHasKey) Matches 

func (nhk NotHasKey) Matches(labels Labels) bool

Matches returns the selector result.

func (NotHasKey) String 

func (nhk NotHasKey) String() string

String returns a string representation of the selector.

func (NotHasKey) Validate 

func (nhk NotHasKey) Validate() (err error)

Validate validates the selector.

type NotIn 

type NotIn struct {
	Key    string
	Values []string
}

NotIn returns if a key does not match a set of values.

func (NotIn) Matches 

func (ni NotIn) Matches(labels Labels) bool

Matches returns the selector result.

func (NotIn) String 

func (ni NotIn) String() string

String returns a string representation of the selector.

func (NotIn) Validate 

func (ni NotIn) Validate() (err error)

Validate validates the selector.

type Option 

type Option func(p *Parser)

Option is a tweak to selector parsing.

type ParseError added in v1.20210103.1 

type ParseError struct {
	Err      error
	Input    string
	Position int
	Message  string
}

ParseError is a specific parse error.

func (ParseError) Class added in v1.20210103.1 

func (pe ParseError) Class() error

Class implements ex.ClassProvider.

func (ParseError) Error added in v1.20210103.1 

func (pe ParseError) Error() string

String implements error.

func (ParseError) Unwrap added in v1.20210103.1 

func (pe ParseError) Unwrap() error

Unwrap implements unwrap.

type Parser 

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

Parser parses a selector incrementally.

func (*Parser) Parse 

func (p *Parser) Parse() (Selector, error)

Parse does the actual parsing.

type Selector 

type Selector interface {
	Matches(labels Labels) bool
	Validate() error
	String() string
}

Selector is the common interface for selector types.

func MustParse 

func MustParse(query string, opts ...Option) Selector

MustParse parses the selector but will panic if there is an issue.

func Parse 

func Parse(query string, opts ...Option) (Selector, error)

Parse takes a string representing a selector and returns a selector object, or an error. The input will cause an error if it does not follow this form: 

<selector-syntax>         ::= <requirement> | <requirement> "," <selector-syntax>
<requirement>             ::= [!] KEY [ <set-based-restriction> | <exact-match-restriction> ]
<set-based-restriction>   ::= "" | <inclusion-exclusion> <value-set>
<inclusion-exclusion>     ::= <inclusion> | <exclusion>
<exclusion>               ::= "notin"
<inclusion>               ::= "in"
<value-set>               ::= "(" <values> ")"
<values>                  ::= VALUE | VALUE "," <values>
<exact-match-restriction> ::= ["="|"=="|"!="] VALUE

KEY is a sequence of one or more characters following: [ DNS_SUBDOMAIN "/" ] DNS_LABEL.

  • DNS_SUBDOMAIN is a sequence of one or more characters ([a-z0-9-.]), and must start and end with an alphanumeric ([a-z0-9]). Symbol characters ('.', '-') cannot repeat. Max length is 253 characters.
  • DNS_LABEL is a sequence of one or more characters ([A-Za-z0-9_-.]). Max length is 63 characters.

VALUE is a sequence of zero or more characters ([A-Za-z0-9_-.]). Values must start and end with an alphanumeric ([a-z0-9A-Z]). Max length is 63 characters. Delimiter is white space: (' ', '\t')

Example of valid syntax: 

"x in (foo,,baz),y,z notin ()"

Note: 

(1) Inclusion - " in " - denotes that the KEY exists and is equal to any of the
    VALUEs in its requirement
(2) Exclusion - " notin " - denotes that the KEY is not equal to any
    of the VALUEs in its requirement or does not exist
(3) The empty string is a valid VALUE
(4) A requirement with just a KEY - as in "y" above - denotes that
    the KEY exists and can be any VALUE.
(5) A requirement with just !KEY requires that the KEY not exist.

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