/
ast.go
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/
ast.go
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// Copyright (c) 2016-2017 Tigera, Inc. All rights reserved.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package parser
import (
_ "crypto/sha256" // register hash func
"strings"
"github.com/projectcalico/libcalico-go/lib/hash"
)
// Labels defines the interface of labels that can be used by selector
type Labels interface {
// Get returns value and presence of the given labelName
Get(labelName string) (value string, present bool)
}
// MapAsLabels allows you use map as labels
type MapAsLabels map[string]string
// Get returns the value and presence of the given labelName key in the MapAsLabels
func (l MapAsLabels) Get(labelName string) (value string, present bool) {
value, present = l[labelName]
return
}
// Selector represents a label selector.
type Selector interface {
// Evaluate evaluates the selector against the given labels expressed as a concrete map.
Evaluate(labels map[string]string) bool
// EvaluateLabels evaluates the selector against the given labels expressed as an interface.
// This allows for labels that are calculated on the fly.
EvaluateLabels(labels Labels) bool
// String returns a string that represents this selector.
String() string
// UniqueID returns the unique ID that represents this selector.
UniqueID() string
}
type selectorRoot struct {
root node
cachedString *string
cachedHash *string
}
func (sel selectorRoot) Evaluate(labels map[string]string) bool {
return sel.EvaluateLabels(MapAsLabels(labels))
}
func (sel selectorRoot) EvaluateLabels(labels Labels) bool {
return sel.root.Evaluate(labels)
}
func (sel selectorRoot) String() string {
if sel.cachedString == nil {
fragments := sel.root.collectFragments([]string{})
joined := strings.Join(fragments, "")
sel.cachedString = &joined
}
return *sel.cachedString
}
func (sel selectorRoot) UniqueID() string {
if sel.cachedHash == nil {
hash := hash.MakeUniqueID("s", sel.String())
sel.cachedHash = &hash
}
return *sel.cachedHash
}
var _ Selector = (*selectorRoot)(nil)
type node interface {
Evaluate(labels Labels) bool
collectFragments(fragments []string) []string
}
type LabelEqValueNode struct {
LabelName string
Value string
}
func (node LabelEqValueNode) Evaluate(labels Labels) bool {
val, ok := labels.Get(node.LabelName)
if ok {
return val == node.Value
}
return false
}
func (node LabelEqValueNode) collectFragments(fragments []string) []string {
var quote string
if strings.Contains(node.Value, `"`) {
quote = `'`
} else {
quote = `"`
}
return append(fragments, node.LabelName, " == ", quote, node.Value, quote)
}
type LabelInSetNode struct {
LabelName string
Value StringSet
}
func (node LabelInSetNode) Evaluate(labels Labels) bool {
val, ok := labels.Get(node.LabelName)
if ok {
return node.Value.Contains(val)
}
return false
}
func (node LabelInSetNode) collectFragments(fragments []string) []string {
return collectInOpFragments(fragments, node.LabelName, "in", node.Value)
}
type LabelNotInSetNode struct {
LabelName string
Value StringSet
}
func (node LabelNotInSetNode) Evaluate(labels Labels) bool {
val, ok := labels.Get(node.LabelName)
if ok {
return !node.Value.Contains(val)
}
return true
}
func (node LabelNotInSetNode) collectFragments(fragments []string) []string {
return collectInOpFragments(fragments, node.LabelName, "not in", node.Value)
}
// collectInOpFragments is a shared implementation of collectFragments
// for the 'in' and 'not in' operators.
func collectInOpFragments(fragments []string, labelName, op string, values StringSet) []string {
var quote string
fragments = append(fragments, labelName, " ", op, " {")
first := true
for _, s := range values {
if strings.Contains(s, `"`) {
quote = `'`
} else {
quote = `"`
}
if !first {
fragments = append(fragments, ", ")
} else {
first = false
}
fragments = append(fragments, quote, s, quote)
}
fragments = append(fragments, "}")
return fragments
}
type LabelNeValueNode struct {
LabelName string
Value string
}
func (node LabelNeValueNode) Evaluate(labels Labels) bool {
val, ok := labels.Get(node.LabelName)
if ok {
return val != node.Value
}
return true
}
func (node LabelNeValueNode) collectFragments(fragments []string) []string {
var quote string
if strings.Contains(node.Value, `"`) {
quote = `'`
} else {
quote = `"`
}
return append(fragments, node.LabelName, " != ", quote, node.Value, quote)
}
type HasNode struct {
LabelName string
}
func (node HasNode) Evaluate(labels Labels) bool {
_, ok := labels.Get(node.LabelName)
if ok {
return true
}
return false
}
func (node HasNode) collectFragments(fragments []string) []string {
return append(fragments, "has(", node.LabelName, ")")
}
type NotNode struct {
Operand node
}
func (node NotNode) Evaluate(labels Labels) bool {
return !node.Operand.Evaluate(labels)
}
func (node NotNode) collectFragments(fragments []string) []string {
fragments = append(fragments, "!")
return node.Operand.collectFragments(fragments)
}
type AndNode struct {
Operands []node
}
func (node AndNode) Evaluate(labels Labels) bool {
for _, operand := range node.Operands {
if !operand.Evaluate(labels) {
return false
}
}
return true
}
func (node AndNode) collectFragments(fragments []string) []string {
fragments = append(fragments, "(")
fragments = node.Operands[0].collectFragments(fragments)
for _, op := range node.Operands[1:] {
fragments = append(fragments, " && ")
fragments = op.collectFragments(fragments)
}
fragments = append(fragments, ")")
return fragments
}
type OrNode struct {
Operands []node
}
func (node OrNode) Evaluate(labels Labels) bool {
for _, operand := range node.Operands {
if operand.Evaluate(labels) {
return true
}
}
return false
}
func (node OrNode) collectFragments(fragments []string) []string {
fragments = append(fragments, "(")
fragments = node.Operands[0].collectFragments(fragments)
for _, op := range node.Operands[1:] {
fragments = append(fragments, " || ")
fragments = op.collectFragments(fragments)
}
fragments = append(fragments, ")")
return fragments
}
type AllNode struct {
}
func (node AllNode) Evaluate(labels Labels) bool {
return true
}
func (node AllNode) collectFragments(fragments []string) []string {
return append(fragments, "all()")
}