37 lines
807 B
Go
37 lines
807 B
Go
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package depgraph
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import (
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"github.com/hashicorp/terraform/digraph"
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)
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// Dependency is used to create a directed edge between two nouns.
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// One noun may depend on another and provide version constraints
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// that cannot be violated
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type Dependency struct {
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Name string
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Meta interface{}
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Constraints []Constraint
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Source *Noun
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Target *Noun
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}
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// Constraint is used by dependencies to allow arbitrary constraints
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// between nouns
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type Constraint interface {
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Satisfied(head, tail *Noun) (bool, error)
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}
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// Head returns the source, or dependent noun
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func (d *Dependency) Head() digraph.Node {
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return d.Source
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}
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// Tail returns the target, or depended upon noun
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func (d *Dependency) Tail() digraph.Node {
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return d.Target
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}
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func (d *Dependency) String() string {
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return d.Name
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}
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