package version
import (
"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 {
return nil, 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 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
}
