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constraint.go
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constraint.go
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package version
import (
"encoding/json"
"fmt"
"regexp"
"strings"
)
// Constraint represents a single constraint for a version, such as
// ">= 1.0".
type Constraint struct {
f constraintFunc
check *Version
original string
}
// 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]constraintFunc
var constraintRegexp *regexp.Regexp
func init() {
constraintOperators = map[string]constraintFunc{
"": constraintEqual,
"=": constraintEqual,
"!=": constraintNotEqual,
">": constraintGreaterThan,
"<": constraintLessThan,
">=": constraintGreaterThanEqual,
"<=": constraintLessThanEqual,
"~>": 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
}
// 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
}
// 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)
}
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 {
// This is a panic because the regular expression above should
// properly validate any version.
panic(err)
}
return &Constraint{
f: constraintOperators[matches[1]],
check: check,
original: v,
}, nil
}
//-------------------------------------------------------------------
// Constraint functions
//-------------------------------------------------------------------
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 v.Compare(c) == 1
}
func constraintLessThan(v, c *Version) bool {
return v.Compare(c) == -1
}
func constraintGreaterThanEqual(v, c *Version) bool {
return v.Compare(c) >= 0
}
func constraintLessThanEqual(v, c *Version) bool {
return v.Compare(c) <= 0
}
func constraintPessimistic(v, c *Version) bool {
if v.LessThan(c) {
return false
}
for i := 0; i < c.si-1; i++ {
if v.segments[i] != c.segments[i] {
return false
}
}
return true
}
// MarshalJSON - implement the json-Marshaler interface
func (c *Constraints) MarshalJSON() ([]byte, error) {
return json.Marshal(c.String())
}
// UnmarshalJSON - implement the json-Unmarshaler interface
func (c *Constraints) UnmarshalJSON(data []byte) (err error) {
var constraintStr string
var nc Constraints
err = json.Unmarshal(data, &constraintStr)
if err != nil {
return
}
nc, err = NewConstraint(constraintStr)
if err != nil {
return
}
*c = nc
return
}
// MarshalYAML - implement the YAML-Marshaler interface (gopkg.in/yaml.v2)
func (c *Constraints) MarshalYAML() (str interface{}, err error) {
str = c.String()
return
}
// UnmarshalYAML - implement the yaml-Unmarshaler interface (gopkg.in/yaml.v2)
func (c *Constraints) UnmarshalYAML(unmarshal func(interface{}) error) (err error) {
var constraintStr string
var nc Constraints
if err = unmarshal(&constraintStr); err != nil {
return
}
nc, err = NewConstraint(constraintStr)
if err != nil {
return
}
*c = nc
return
}