Arch Linux helpers and parsers
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package version
import (
"fmt"
"strings"
)
// Operator is a dependancy comparison operator
type Operator string
// ParseOperator parses a string as operator
func ParseOperator(s string) (Operator, error) {
op, _, err := parseOperator(s, true)
return op, err
}
func parseOperator(s string, strict bool) (op Operator, ends int, err error) {
op = Operator(s)
if ends = strings.IndexFunc(s, func(r rune) bool {
return r != '<' && r != '>' && r != '='
}); ends != -1 {
// We've hit something not <, > or =
if !strict {
op = op[:ends]
}
} else {
ends = len(op)
}
if _, known := operators[op]; !known {
err = fmt.Errorf("version: invalid operator %q", op)
op = None
return
}
return
}
// Operator types
const (
None Operator = ""
LessThan Operator = "<"
LessThenOrEqualTo Operator = "<="
EqualTo Operator = "="
MoreThanOrEqualTo Operator = ">="
MoreThan Operator = ">"
)
var operators = map[Operator]bool{
None: true,
LessThan: true,
LessThenOrEqualTo: true,
EqualTo: true,
MoreThanOrEqualTo: true,
MoreThan: true,
}
func (op Operator) String() string {
return string(op)
}
// Dependency describes a dependency
type Dependency struct {
Operator
Version
}
// ParseDependency parses a string into its prefix and the dependency specifier
func ParseDependency(s string) (string, Dependency, error) {
var (
name = s
ops string
dep Dependency
offset, ends int
err error
)
if offset = strings.Index(name, ": "); offset != -1 {
// Dependancies may have a comment, which is separated by ": " (notice the
// space, which is different from epoch)
name = name[:offset]
}
if offset = strings.IndexFunc(name, func(r rune) bool {
return r == '<' || r == '>' || r == '='
}); offset != -1 {
// We have an operator, probably
name, ops = name[:offset], name[offset:]
if dep.Operator, ends, err = parseOperator(ops, false); err != nil {
return "", Dependency{}, err
}
dep.Version = Parse(ops[ends:])
}
return name, dep, nil
}
// Match this dependency against a version
func (dep Dependency) Match(version Version) bool {
if dep.Operator == None {
return true
}
cmp := Compare(version, dep.Version)
switch dep.Operator {
case LessThan:
return cmp == -1
case LessThenOrEqualTo:
return cmp <= 0
case EqualTo:
return cmp == 0
case MoreThanOrEqualTo:
return cmp >= 0
case MoreThan:
return cmp == 1
default:
return false
}
}
func (dep Dependency) String() string {
if dep.Operator == None {
return ""
}
return dep.Operator.String() + dep.Version.String()
}