Instana tracer implementation

vendor/github.com/looplab/fsm/utils.go

@@ -0,0 +1,45 @@
+package fsm
+
+import (
+	"bytes"
+	"fmt"
+)
+
+// Visualize outputs a visualization of a FSM in Graphviz format.
+func Visualize(fsm *FSM) string {
+	var buf bytes.Buffer
+
+	states := make(map[string]int)
+
+	buf.WriteString(fmt.Sprintf(`digraph fsm {`))
+	buf.WriteString("\n")
+
+	// make sure the initial state is at top
+	for k, v := range fsm.transitions {
+		if k.src == fsm.current {
+			states[k.src]++
+			states[v]++
+			buf.WriteString(fmt.Sprintf(`    "%s" -> "%s" [ label = "%s" ];`, k.src, v, k.event))
+			buf.WriteString("\n")
+		}
+	}
+
+	for k, v := range fsm.transitions {
+		if k.src != fsm.current {
+			states[k.src]++
+			states[v]++
+			buf.WriteString(fmt.Sprintf(`    "%s" -> "%s" [ label = "%s" ];`, k.src, v, k.event))
+			buf.WriteString("\n")
+		}
+	}
+
+	buf.WriteString("\n")
+
+	for k := range states {
+		buf.WriteString(fmt.Sprintf(`    "%s";`, k))
+		buf.WriteString("\n")
+	}
+	buf.WriteString(fmt.Sprintln("}"))
+
+	return buf.String()
+}