Scott Baker | 1fe7273 | 2019-10-21 10:58:51 -0700 | [diff] [blame] | 1 | package version |
| 2 | |
| 3 | import ( |
| 4 | "fmt" |
| 5 | "reflect" |
| 6 | "regexp" |
| 7 | "strings" |
| 8 | ) |
| 9 | |
| 10 | // Constraint represents a single constraint for a version, such as |
| 11 | // ">= 1.0". |
| 12 | type Constraint struct { |
| 13 | f constraintFunc |
| 14 | check *Version |
| 15 | original string |
| 16 | } |
| 17 | |
| 18 | // Constraints is a slice of constraints. We make a custom type so that |
| 19 | // we can add methods to it. |
| 20 | type Constraints []*Constraint |
| 21 | |
| 22 | type constraintFunc func(v, c *Version) bool |
| 23 | |
| 24 | var constraintOperators map[string]constraintFunc |
| 25 | |
| 26 | var constraintRegexp *regexp.Regexp |
| 27 | |
| 28 | func init() { |
| 29 | constraintOperators = map[string]constraintFunc{ |
| 30 | "": constraintEqual, |
| 31 | "=": constraintEqual, |
| 32 | "!=": constraintNotEqual, |
| 33 | ">": constraintGreaterThan, |
| 34 | "<": constraintLessThan, |
| 35 | ">=": constraintGreaterThanEqual, |
| 36 | "<=": constraintLessThanEqual, |
| 37 | "~>": constraintPessimistic, |
| 38 | } |
| 39 | |
| 40 | ops := make([]string, 0, len(constraintOperators)) |
| 41 | for k := range constraintOperators { |
| 42 | ops = append(ops, regexp.QuoteMeta(k)) |
| 43 | } |
| 44 | |
| 45 | constraintRegexp = regexp.MustCompile(fmt.Sprintf( |
| 46 | `^\s*(%s)\s*(%s)\s*$`, |
| 47 | strings.Join(ops, "|"), |
| 48 | VersionRegexpRaw)) |
| 49 | } |
| 50 | |
| 51 | // NewConstraint will parse one or more constraints from the given |
| 52 | // constraint string. The string must be a comma-separated list of |
| 53 | // constraints. |
| 54 | func NewConstraint(v string) (Constraints, error) { |
| 55 | vs := strings.Split(v, ",") |
| 56 | result := make([]*Constraint, len(vs)) |
| 57 | for i, single := range vs { |
| 58 | c, err := parseSingle(single) |
| 59 | if err != nil { |
| 60 | return nil, err |
| 61 | } |
| 62 | |
| 63 | result[i] = c |
| 64 | } |
| 65 | |
| 66 | return Constraints(result), nil |
| 67 | } |
| 68 | |
| 69 | // Check tests if a version satisfies all the constraints. |
| 70 | func (cs Constraints) Check(v *Version) bool { |
| 71 | for _, c := range cs { |
| 72 | if !c.Check(v) { |
| 73 | return false |
| 74 | } |
| 75 | } |
| 76 | |
| 77 | return true |
| 78 | } |
| 79 | |
| 80 | // Returns the string format of the constraints |
| 81 | func (cs Constraints) String() string { |
| 82 | csStr := make([]string, len(cs)) |
| 83 | for i, c := range cs { |
| 84 | csStr[i] = c.String() |
| 85 | } |
| 86 | |
| 87 | return strings.Join(csStr, ",") |
| 88 | } |
| 89 | |
| 90 | // Check tests if a constraint is validated by the given version. |
| 91 | func (c *Constraint) Check(v *Version) bool { |
| 92 | return c.f(v, c.check) |
| 93 | } |
| 94 | |
| 95 | func (c *Constraint) String() string { |
| 96 | return c.original |
| 97 | } |
| 98 | |
| 99 | func parseSingle(v string) (*Constraint, error) { |
| 100 | matches := constraintRegexp.FindStringSubmatch(v) |
| 101 | if matches == nil { |
| 102 | return nil, fmt.Errorf("Malformed constraint: %s", v) |
| 103 | } |
| 104 | |
| 105 | check, err := NewVersion(matches[2]) |
| 106 | if err != nil { |
| 107 | return nil, err |
| 108 | } |
| 109 | |
| 110 | return &Constraint{ |
| 111 | f: constraintOperators[matches[1]], |
| 112 | check: check, |
| 113 | original: v, |
| 114 | }, nil |
| 115 | } |
| 116 | |
| 117 | func prereleaseCheck(v, c *Version) bool { |
| 118 | switch vPre, cPre := v.Prerelease() != "", c.Prerelease() != ""; { |
| 119 | case cPre && vPre: |
| 120 | // A constraint with a pre-release can only match a pre-release version |
| 121 | // with the same base segments. |
| 122 | return reflect.DeepEqual(c.Segments64(), v.Segments64()) |
| 123 | |
| 124 | case !cPre && vPre: |
| 125 | // A constraint without a pre-release can only match a version without a |
| 126 | // pre-release. |
| 127 | return false |
| 128 | |
| 129 | case cPre && !vPre: |
| 130 | // OK, except with the pessimistic operator |
| 131 | case !cPre && !vPre: |
| 132 | // OK |
| 133 | } |
| 134 | return true |
| 135 | } |
| 136 | |
| 137 | //------------------------------------------------------------------- |
| 138 | // Constraint functions |
| 139 | //------------------------------------------------------------------- |
| 140 | |
| 141 | func constraintEqual(v, c *Version) bool { |
| 142 | return v.Equal(c) |
| 143 | } |
| 144 | |
| 145 | func constraintNotEqual(v, c *Version) bool { |
| 146 | return !v.Equal(c) |
| 147 | } |
| 148 | |
| 149 | func constraintGreaterThan(v, c *Version) bool { |
| 150 | return prereleaseCheck(v, c) && v.Compare(c) == 1 |
| 151 | } |
| 152 | |
| 153 | func constraintLessThan(v, c *Version) bool { |
| 154 | return prereleaseCheck(v, c) && v.Compare(c) == -1 |
| 155 | } |
| 156 | |
| 157 | func constraintGreaterThanEqual(v, c *Version) bool { |
| 158 | return prereleaseCheck(v, c) && v.Compare(c) >= 0 |
| 159 | } |
| 160 | |
| 161 | func constraintLessThanEqual(v, c *Version) bool { |
| 162 | return prereleaseCheck(v, c) && v.Compare(c) <= 0 |
| 163 | } |
| 164 | |
| 165 | func constraintPessimistic(v, c *Version) bool { |
| 166 | // Using a pessimistic constraint with a pre-release, restricts versions to pre-releases |
| 167 | if !prereleaseCheck(v, c) || (c.Prerelease() != "" && v.Prerelease() == "") { |
| 168 | return false |
| 169 | } |
| 170 | |
| 171 | // If the version being checked is naturally less than the constraint, then there |
| 172 | // is no way for the version to be valid against the constraint |
| 173 | if v.LessThan(c) { |
| 174 | return false |
| 175 | } |
| 176 | // We'll use this more than once, so grab the length now so it's a little cleaner |
| 177 | // to write the later checks |
| 178 | cs := len(c.segments) |
| 179 | |
| 180 | // If the version being checked has less specificity than the constraint, then there |
| 181 | // is no way for the version to be valid against the constraint |
| 182 | if cs > len(v.segments) { |
| 183 | return false |
| 184 | } |
| 185 | |
| 186 | // Check the segments in the constraint against those in the version. If the version |
| 187 | // being checked, at any point, does not have the same values in each index of the |
| 188 | // constraints segments, then it cannot be valid against the constraint. |
| 189 | for i := 0; i < c.si-1; i++ { |
| 190 | if v.segments[i] != c.segments[i] { |
| 191 | return false |
| 192 | } |
| 193 | } |
| 194 | |
| 195 | // Check the last part of the segment in the constraint. If the version segment at |
| 196 | // this index is less than the constraints segment at this index, then it cannot |
| 197 | // be valid against the constraint |
| 198 | if c.segments[cs-1] > v.segments[cs-1] { |
| 199 | return false |
| 200 | } |
| 201 | |
| 202 | // If nothing has rejected the version by now, it's valid |
| 203 | return true |
| 204 | } |