feat(web): initialize Next.js project with Tailwind CSS and TypeScript setup

pkg/engine/subgraph.go

@@ -0,0 +1,109 @@
+package engine
+
+import (
+	"fmt"
+	"sort"
+)
+
+// LoopBody holds the body node names in topological order for inline execution.
+type LoopBody struct {
+	Order         []string
+	Nodes         map[string]bool
+	TerminalNodes []string
+}
+
+// GetLoopBody identifies the loop body nodes and returns them in topological
+// order for inline execution within the parent ExecutionContext.
+func GetLoopBody(dag *DAG, loopNodeName string) (*LoopBody, error) {
+	var entryNodes []string
+	for _, edge := range dag.Adjacency[loopNodeName] {
+		if edge.SourceOutputIndex == 0 {
+			entryNodes = append(entryNodes, edge.Target)
+		}
+	}
+	if len(entryNodes) == 0 {
+		return nil, fmt.Errorf("loop node %q has no body (no output 0 connections)", loopNodeName)
+	}
+
+	continuationNodes := make(map[string]bool)
+	for _, edge := range dag.Adjacency[loopNodeName] {
+		if edge.SourceOutputIndex == 1 {
+			continuationNodes[edge.Target] = true
+		}
+	}
+
+	bodyNodes := make(map[string]bool)
+	queue := make([]string, len(entryNodes))
+	copy(queue, entryNodes)
+	for _, n := range entryNodes {
+		bodyNodes[n] = true
+	}
+	for len(queue) > 0 {
+		current := queue[0]
+		queue = queue[1:]
+		for _, edge := range dag.Adjacency[current] {
+			next := edge.Target
+			if next == loopNodeName || continuationNodes[next] || bodyNodes[next] {
+				continue
+			}
+			bodyNodes[next] = true
+			queue = append(queue, next)
+		}
+	}
+
+	inDegree := make(map[string]int, len(bodyNodes))
+	for name := range bodyNodes {
+		inDegree[name] = 0
+	}
+	for name := range bodyNodes {
+		for _, edge := range dag.Adjacency[name] {
+			if bodyNodes[edge.Target] {
+				inDegree[edge.Target]++
+			}
+		}
+	}
+
+	var topoQueue []string
+	for name, deg := range inDegree {
+		if deg == 0 {
+			topoQueue = append(topoQueue, name)
+		}
+	}
+	sort.Strings(topoQueue)
+
+	var order []string
+	for len(topoQueue) > 0 {
+		current := topoQueue[0]
+		topoQueue = topoQueue[1:]
+		order = append(order, current)
+		for _, edge := range dag.Adjacency[current] {
+			if bodyNodes[edge.Target] {
+				inDegree[edge.Target]--
+				if inDegree[edge.Target] == 0 {
+					topoQueue = append(topoQueue, edge.Target)
+				}
+			}
+		}
+	}
+
+	var terminalNodes []string
+	for name := range bodyNodes {
+		isTerminal := true
+		for _, edge := range dag.Adjacency[name] {
+			if bodyNodes[edge.Target] {
+				isTerminal = false
+				break
+			}
+		}
+		if isTerminal {
+			terminalNodes = append(terminalNodes, name)
+		}
+	}
+	sort.Strings(terminalNodes)
+
+	return &LoopBody{
+		Order:         order,
+		Nodes:         bodyNodes,
+		TerminalNodes: terminalNodes,
+	}, nil
+}