state file support

Author: mandelsoft

flow/cascade.go

@@ -34,20 +34,23 @@ func Cascade(outer dynaml.Binding, template yaml.Node, partial bool, stubs ...ya
 	return Apply(outer, template, prepared)
 }
 
-func discardTemporary(node yaml.Node) yaml.Node {
+func discardTemporary(node yaml.Node) (yaml.Node, CleanupFunction) {
 	if node.Temporary() || node.Local() {
-		return nil
+		return nil, discardTemporary
 	}
-	return node
+	return node, discardTemporary
 }
-func discardLocal(node yaml.Node) yaml.Node {
+
+func discardLocal(node yaml.Node) (yaml.Node, CleanupFunction) {
 	if node.Local() {
-		return nil
+		return nil, discardLocal
 	}
-	return node
+	return node, discardLocal
 }
 
-func Cleanup(node yaml.Node, test func(yaml.Node) yaml.Node) yaml.Node {
+type CleanupFunction func(yaml.Node) (yaml.Node, CleanupFunction)
+
+func Cleanup(node yaml.Node, test CleanupFunction) yaml.Node {
 	if node == nil {
 		return nil
 	}
@@ -56,17 +59,17 @@ func Cleanup(node yaml.Node, test func(yaml.Node) yaml.Node) yaml.Node {
 	case []yaml.Node:
 		r := []yaml.Node{}
 		for _, e := range v {
-			if n := test(e); n != nil {
-				r = append(r, Cleanup(n, test))
+			if n, t := test(e); n != nil {
+				r = append(r, Cleanup(n, t))
 			}
 		}
 		value = r
 
 	case map[string]yaml.Node:
 		r := map[string]yaml.Node{}
 		for k, e := range v {
-			if n := test(e); n != nil {
-				r[k] = Cleanup(n, test)
+			if n, t := test(e); n != nil {
+				r[k] = Cleanup(n, t)
 			}
 		}
 		value = r

flow/environment.go

@@ -282,8 +282,9 @@ type Updateable interface {
 	Deactivate() dynaml.Binding
 }
 
-func updateBinding(root yaml.Node) func(yaml.Node) yaml.Node {
-	return func(node yaml.Node) yaml.Node {
+func updateBinding(root yaml.Node) CleanupFunction {
+	var me CleanupFunction
+	me = func(node yaml.Node) (yaml.Node, CleanupFunction) {
 		if v := node.Value(); v != nil {
 			if static, ok := v.(dynaml.StaticallyScopedValue); ok {
 				debug.Debug("update found static scoped %q\n", static)
@@ -304,20 +305,21 @@ func updateBinding(root yaml.Node) func(yaml.Node) yaml.Node {
 				}
 			}
 		}
-		return node
+		return node, me
 	}
+	return me
 }
 
-func deactivateScopes(node yaml.Node) yaml.Node {
+func deactivateScopes(node yaml.Node) (yaml.Node, CleanupFunction) {
 	if v := node.Value(); v != nil {
 		if lambda, ok := v.(dynaml.StaticallyScopedValue); ok {
 			debug.Debug("deactivate statically scoped node %q\n", lambda)
 			if env := lambda.StaticResolver().(Updateable); env.Active() {
-				return yaml.ReplaceValue(lambda.SetStaticResolver(env.Deactivate()), node)
+				return yaml.ReplaceValue(lambda.SetStaticResolver(env.Deactivate()), node), deactivateScopes
 			}
 		}
 	}
-	return node
+	return node, deactivateScopes
 }
 
 func resolveSymbol(env *DefaultEnvironment, name string, scope *Scope) (yaml.Node, bool, *Scope) {

spiff++.go

@@ -52,6 +52,10 @@ func main() {
 					Name:  "path",
 					Usage: "output is taken from given path",
 				},
+				cli.StringFlag{
+					Name:  "state",
+					Usage: "select state file to maintain",
+				},
 				cli.StringSliceFlag{
 					Name:  "select",
 					Usage: "filter dedicated output fields",
@@ -67,6 +71,7 @@ func main() {
 				merge(c.Args()[0], c.Bool("partial"),
 					c.Bool("json"), c.Bool("split"),
 					c.String("path"), c.StringSlice("select"),
+					c.String("state"),
 					c.Args()[1:])
 			},
 		},
@@ -116,7 +121,27 @@ func main() {
 	app.Run(os.Args)
 }
 
-func merge(templateFilePath string, partial bool, json, split bool, subpath string, selection []string, stubFilePaths []string) {
+func keepAll(node yaml.Node) (yaml.Node, flow.CleanupFunction) {
+	return node, keepAll
+}
+
+func discardNonState(node yaml.Node) (yaml.Node, flow.CleanupFunction) {
+	if node.State() {
+		return node, keepAll
+	}
+	return nil, discardNonState
+}
+
+func fileExists(filename string) bool {
+	info, err := os.Stat(filename)
+	if os.IsNotExist(err) {
+		return false
+	}
+	return !info.IsDir()
+}
+
+func merge(templateFilePath string, partial bool, json, split bool,
+	subpath string, selection []string, stateFilePath string, stubFilePaths []string) {
 	var templateFile []byte
 	var err error
 	var stdin = false
@@ -137,6 +162,17 @@ func merge(templateFilePath string, partial bool, json, split bool, subpath stri
 		log.Fatalln(fmt.Sprintf("error parsing template [%s]:", path.Clean(templateFilePath)), err)
 	}
 
+	var stateData []byte
+
+	if stateFilePath != "" {
+		if len(templateYAMLs) > 1 {
+			log.Fatalln(fmt.Sprintf("state handling not supported gor multi documents [%s]:", path.Clean(templateFilePath)), err)
+		}
+		if fileExists(stateFilePath) {
+			stateData, err = ioutil.ReadFile(stateFilePath)
+		}
+	}
+
 	stubs := []yaml.Node{}
 
 	for _, stubFilePath := range stubFilePaths {
@@ -163,6 +199,14 @@ func merge(templateFilePath string, partial bool, json, split bool, subpath stri
 		stubs = append(stubs, stubYAML)
 	}
 
+	if stateData != nil {
+		stateYAML, err := yaml.Parse(stateFilePath, stateData)
+		if err != nil {
+			log.Fatalln(fmt.Sprintf("error parsing state [%s]:", path.Clean(stateFilePath)), err)
+		}
+		stubs = append(stubs, stateYAML)
+	}
+
 	legend := "\nerror classification:\n" +
 		" *: error in local dynaml expression\n" +
 		" @: dependent of or involved in a cycle\n" +
@@ -198,6 +242,28 @@ func merge(templateFilePath string, partial bool, json, split bool, subpath stri
 				}
 				flowed = node
 			}
+			if stateFilePath != "" {
+				state := flow.Cleanup(flowed, discardNonState)
+				if json {
+					bytes, err = yaml.ToJSON(state)
+				} else {
+					bytes, err = candiedyaml.Marshal(state)
+				}
+				old := false
+				if fileExists(stateFilePath) {
+					os.Rename(stateFilePath, stateFilePath+".bak")
+					old = true
+				}
+				err := ioutil.WriteFile(stateFilePath, bytes, 0664)
+				if err != nil {
+					os.Remove(stateFilePath)
+					os.Remove(stateFilePath)
+					if old {
+						os.Rename(stateFilePath+".bak", stateFilePath)
+					}
+					log.Fatalln(fmt.Sprintf("cannot write state file %q", stateFilePath))
+				}
+			}
 			if len(selection) > 0 {
 				new := map[string]yaml.Node{}
 				for _, p := range selection {

yaml/node.go

@@ -23,6 +23,7 @@ type Node interface {
 	Flags() NodeFlags
 	Temporary() bool
 	Local() bool
+	State() bool
 	ReplaceFlag() bool
 	Preferred() bool
 	Merged() bool