From 082d6901f7f24e98108404fd9df5b531bca5ff67 Mon Sep 17 00:00:00 2001
From: Alex Dadgar <alex.dadgar@gmail.com>
Date: Tue, 3 May 2016 09:50:49 -0700
Subject: [PATCH] visitor

---
 nomad/structs/diff/job.go         |  2 ++
 nomad/structs/diff/job_visitor.go | 52 +++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)
 create mode 100644 nomad/structs/diff/job_visitor.go

diff --git a/nomad/structs/diff/job.go b/nomad/structs/diff/job.go
index 0eaccb9c3..9bbcab955 100644
--- a/nomad/structs/diff/job.go
+++ b/nomad/structs/diff/job.go
@@ -250,6 +250,8 @@ type PrimitiveStructDiff struct {
 	PrimitiveFields []*FieldDiff
 }
 
+// DiffFields performs the diff of the passed fields against the old and new
+// object.
 func (p *PrimitiveStructDiff) DiffFields(old, new interface{}, fields []string) {
 	for _, field := range fields {
 		oldV := getField(old, field)
diff --git a/nomad/structs/diff/job_visitor.go b/nomad/structs/diff/job_visitor.go
new file mode 100644
index 000000000..c9ef9a4cc
--- /dev/null
+++ b/nomad/structs/diff/job_visitor.go
@@ -0,0 +1,52 @@
+package diff
+
+// JobVisitor is the set of types a visitor must implement to traverse a JobDiff
+// structure.
+type JobVisitor interface {
+	VisitJob(*JobDiff)
+	VisitTaskGroups(*TaskGroupsDiff)
+	VisitTaskGroup(*TaskGroupDiff)
+	VisitTasks(*TasksDiff)
+	VisitTask(*TaskDiff)
+	VisitServices(*ServicesDiff)
+	VisitService(*ServiceDiff)
+	VisitServiceChecks(*ServiceChecksDiff)
+	VisitServiceCheck(*ServiceCheckDiff)
+	VisitTaskArtifactsDiff(*TaskArtifactsDiff)
+	VisitTaskArtifactDiff(*TaskArtifactDiff)
+	VisitResources(*ResourcesDiff)
+	VisitNetworkResources(*NetworkResourcesDiff)
+	VisitNetworkResource(*NetworkResourceDiff)
+	VisitPorts(*PortsDiff)
+	VisitPrimitiveStruct(*PrimitiveStructDiff)
+	VisitField(*FieldDiff)
+	VisitStringSet(*StringSetDiff)
+	VisitStringMap(*StringMapDiff)
+	VisitStringValueDelta(*StringValueDelta)
+}
+
+// JobDiffComponent is the method a diff component must implement to be visited.
+type JobDiffComponent interface {
+	Accept(JobVisitor)
+}
+
+func (j *JobDiff) Accept(v JobVisitor)              { v.VisitJob(j) }
+func (t *TaskGroupsDiff) Accept(v JobVisitor)       { v.VisitTaskGroups(t) }
+func (t *TaskGroupDiff) Accept(v JobVisitor)        { v.VisitTaskGroup(t) }
+func (t *TasksDiff) Accept(v JobVisitor)            { v.VisitTasks(t) }
+func (t *TaskDiff) Accept(v JobVisitor)             { v.VisitTask(t) }
+func (s *ServicesDiff) Accept(v JobVisitor)         { v.VisitServices(s) }
+func (s *ServiceDiff) Accept(v JobVisitor)          { v.VisitService(s) }
+func (s *ServiceChecksDiff) Accept(v JobVisitor)    { v.VisitServiceChecks(s) }
+func (s *ServiceCheckDiff) Accept(v JobVisitor)     { v.VisitServiceCheck(s) }
+func (t *TaskArtifactsDiff) Accept(v JobVisitor)    { v.VisitTaskArtifactsDiff(t) }
+func (t *TaskArtifactDiff) Accept(v JobVisitor)     { v.VisitTaskArtifactDiff(t) }
+func (r *ResourcesDiff) Accept(v JobVisitor)        { v.VisitResources(r) }
+func (n *NetworkResourcesDiff) Accept(v JobVisitor) { v.VisitNetworkResources(n) }
+func (n *NetworkResourceDiff) Accept(v JobVisitor)  { v.VisitNetworkResource(n) }
+func (p *PortsDiff) Accept(v JobVisitor)            { v.VisitPorts(p) }
+func (p *PrimitiveStructDiff) Accept(v JobVisitor)  { v.VisitPrimitiveStruct(p) }
+func (f *FieldDiff) Accept(v JobVisitor)            { v.VisitField(f) }
+func (s *StringSetDiff) Accept(v JobVisitor)        { v.VisitStringSet(s) }
+func (s *StringMapDiff) Accept(v JobVisitor)        { v.VisitStringMap(s) }
+func (s *StringValueDelta) Accept(v JobVisitor)     { v.VisitStringValueDelta(s) }