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constraint.go
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constraint.go
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// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0
package version
import (
"fmt"
"regexp"
"sort"
"strings"
)
// Constraint represents a single constraint for a version, such as
// ">= 1.0".
type Constraint struct {
f constraintFunc
op operator
check *Version
original string
}
func (c *Constraint) Equals(con *Constraint) bool {
return c.op == con.op && c.check.Equal(con.check)
}
// Constraints is a slice of constraints. We make a custom type so that
// we can add methods to it.
type Constraints []*Constraint
type constraintFunc func(v, c *Version) bool
var constraintOperators map[string]constraintOperation
type constraintOperation struct {
op operator
f constraintFunc
}
var constraintRegexp *regexp.Regexp
func init() {
constraintOperators = map[string]constraintOperation{
"": {op: equal, f: constraintEqual},
"=": {op: equal, f: constraintEqual},
"!=": {op: notEqual, f: constraintNotEqual},
">": {op: greaterThan, f: constraintGreaterThan},
"<": {op: lessThan, f: constraintLessThan},
">=": {op: greaterThanEqual, f: constraintGreaterThanEqual},
"<=": {op: lessThanEqual, f: constraintLessThanEqual},
"~>": {op: pessimistic, f: constraintPessimistic},
}
ops := make([]string, 0, len(constraintOperators))
for k := range constraintOperators {
ops = append(ops, regexp.QuoteMeta(k))
}
constraintRegexp = regexp.MustCompile(fmt.Sprintf(
`^\s*(%s)\s*(%s)\s*$`,
strings.Join(ops, "|"),
VersionRegexpRaw))
}
// NewConstraint will parse one or more constraints from the given
// constraint string. The string must be a comma-separated list of
// constraints.
func NewConstraint(v string) (Constraints, error) {
vs := strings.Split(v, ",")
result := make([]*Constraint, len(vs))
for i, single := range vs {
c, err := parseSingle(single)
if err != nil {
return nil, err
}
result[i] = c
}
return Constraints(result), nil
}
// MustConstraints is a helper that wraps a call to a function
// returning (Constraints, error) and panics if error is non-nil.
func MustConstraints(c Constraints, err error) Constraints {
if err != nil {
panic(err)
}
return c
}
// Check tests if a version satisfies all the constraints.
func (cs Constraints) Check(v *Version) bool {
for _, c := range cs {
if !c.Check(v) {
return false
}
}
return true
}
// Equals compares Constraints with other Constraints
// for equality. This may not represent logical equivalence
// of compared constraints.
// e.g. even though '>0.1,>0.2' is logically equivalent
// to '>0.2' it is *NOT* treated as equal.
//
// Missing operator is treated as equal to '=', whitespaces
// are ignored and constraints are sorted before comaparison.
func (cs Constraints) Equals(c Constraints) bool {
if len(cs) != len(c) {
return false
}
// make copies to retain order of the original slices
left := make(Constraints, len(cs))
copy(left, cs)
sort.Stable(left)
right := make(Constraints, len(c))
copy(right, c)
sort.Stable(right)
// compare sorted slices
for i, con := range left {
if !con.Equals(right[i]) {
return false
}
}
return true
}
func (cs Constraints) Len() int {
return len(cs)
}
func (cs Constraints) Less(i, j int) bool {
if cs[i].op < cs[j].op {
return true
}
if cs[i].op > cs[j].op {
return false
}
return cs[i].check.LessThan(cs[j].check)
}
func (cs Constraints) Swap(i, j int) {
cs[i], cs[j] = cs[j], cs[i]
}
// Returns the string format of the constraints
func (cs Constraints) String() string {
csStr := make([]string, len(cs))
for i, c := range cs {
csStr[i] = c.String()
}
return strings.Join(csStr, ",")
}
// Check tests if a constraint is validated by the given version.
func (c *Constraint) Check(v *Version) bool {
return c.f(v, c.check)
}
// Prerelease returns true if the version underlying this constraint
// contains a prerelease field.
func (c *Constraint) Prerelease() bool {
return len(c.check.Prerelease()) > 0
}
func (c *Constraint) String() string {
return c.original
}
func parseSingle(v string) (*Constraint, error) {
matches := constraintRegexp.FindStringSubmatch(v)
if matches == nil {
return nil, fmt.Errorf("Malformed constraint: %s", v)
}
check, err := NewVersion(matches[2])
if err != nil {
return nil, err
}
cop := constraintOperators[matches[1]]
return &Constraint{
f: cop.f,
op: cop.op,
check: check,
original: v,
}, nil
}
func prereleaseCheck(v, c *Version) bool {
switch vPre, cPre := v.Prerelease() != "", c.Prerelease() != ""; {
case cPre && vPre:
// A constraint with a pre-release can only match a pre-release version
// with the same base segments.
return v.equalSegments(c)
case !cPre && vPre:
// A constraint without a pre-release can only match a version without a
// pre-release.
return false
case cPre && !vPre:
// OK, except with the pessimistic operator
case !cPre && !vPre:
// OK
}
return true
}
//-------------------------------------------------------------------
// Constraint functions
//-------------------------------------------------------------------
type operator rune
const (
equal operator = '='
notEqual operator = '≠'
greaterThan operator = '>'
lessThan operator = '<'
greaterThanEqual operator = '≥'
lessThanEqual operator = '≤'
pessimistic operator = '~'
)
func constraintEqual(v, c *Version) bool {
return v.Equal(c)
}
func constraintNotEqual(v, c *Version) bool {
return !v.Equal(c)
}
func constraintGreaterThan(v, c *Version) bool {
return prereleaseCheck(v, c) && v.Compare(c) == 1
}
func constraintLessThan(v, c *Version) bool {
return prereleaseCheck(v, c) && v.Compare(c) == -1
}
func constraintGreaterThanEqual(v, c *Version) bool {
return prereleaseCheck(v, c) && v.Compare(c) >= 0
}
func constraintLessThanEqual(v, c *Version) bool {
return prereleaseCheck(v, c) && v.Compare(c) <= 0
}
func constraintPessimistic(v, c *Version) bool {
// Using a pessimistic constraint with a pre-release, restricts versions to pre-releases
if !prereleaseCheck(v, c) || (c.Prerelease() != "" && v.Prerelease() == "") {
return false
}
// If the version being checked is naturally less than the constraint, then there
// is no way for the version to be valid against the constraint
if v.LessThan(c) {
return false
}
// We'll use this more than once, so grab the length now so it's a little cleaner
// to write the later checks
cs := len(c.segments)
// If the version being checked has less specificity than the constraint, then there
// is no way for the version to be valid against the constraint
if cs > len(v.segments) {
return false
}
// Check the segments in the constraint against those in the version. If the version
// being checked, at any point, does not have the same values in each index of the
// constraints segments, then it cannot be valid against the constraint.
for i := 0; i < c.si-1; i++ {
if v.segments[i] != c.segments[i] {
return false
}
}
// Check the last part of the segment in the constraint. If the version segment at
// this index is less than the constraints segment at this index, then it cannot
// be valid against the constraint
if c.segments[cs-1] > v.segments[cs-1] {
return false
}
// If nothing has rejected the version by now, it's valid
return true
}