108 lines
2.2 KiB
Go
108 lines
2.2 KiB
Go
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package config
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import (
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"reflect"
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"regexp"
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"github.com/mitchellh/reflectwalk"
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)
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// interpRegexp is a regexp that matches interpolations such as ${foo.bar}
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var interpRegexp *regexp.Regexp = regexp.MustCompile(
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`(?i)(\$+)\{([*-.a-z0-9_]+)\}`)
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// interpolationWalker implements interfaces for the reflectwalk package
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// (github.com/mitchellh/reflectwalk) that can be used to automatically
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// execute a callback for an interpolation.
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type interpolationWalker struct {
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// F must be one of interpolationWalkerFunc or
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// interpolationReplaceWalkerFunc.
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F interpolationWalkerFunc
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Replace bool
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key []string
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loc reflectwalk.Location
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cs []reflect.Value
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csData interface{}
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}
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type interpolationWalkerFunc func(Interpolation) (string, error)
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func (w *interpolationWalker) Enter(loc reflectwalk.Location) error {
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w.loc = loc
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return nil
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}
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func (w *interpolationWalker) Exit(loc reflectwalk.Location) error {
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w.loc = reflectwalk.None
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switch loc {
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case reflectwalk.Map:
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w.cs = w.cs[:len(w.cs)-1]
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case reflectwalk.MapValue:
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w.key = w.key[:len(w.key)-1]
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}
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return nil
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}
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func (w *interpolationWalker) Map(m reflect.Value) error {
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w.cs = append(w.cs, m)
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return nil
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}
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func (w *interpolationWalker) MapElem(m, k, v reflect.Value) error {
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w.csData = k
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w.key = append(w.key, k.String())
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return nil
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}
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func (w *interpolationWalker) Primitive(v reflect.Value) error {
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// We only care about strings
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if v.Kind() == reflect.Interface {
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v = v.Elem()
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}
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if v.Kind() != reflect.String {
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return nil
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}
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// XXX: This can be a lot more efficient if we used a real
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// parser. A regexp is a hammer though that will get this working.
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matches := interpRegexp.FindAllStringSubmatch(v.String(), -1)
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if len(matches) == 0 {
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return nil
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}
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for _, match := range matches {
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dollars := len(match[1])
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// If there are even amounts of dollar signs, then it is escaped
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if dollars%2 == 0 {
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continue
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}
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// Interpolation found, instantiate it
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key := match[2]
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i, err := NewInterpolation(key)
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if err != nil {
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return err
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}
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replaceVal, err := w.F(i)
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if err != nil {
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return err
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}
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if w.Replace {
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// TODO(mitchellh): replace
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println(replaceVal)
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}
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return nil
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}
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return nil
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}
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