v0.1.0 initial commit

tui/tree_builder.go

@@ -0,0 +1,52 @@
+package tui
+
+// TreeBuilder helps construct flattened visible node list from hierarchical data
+type TreeBuilder struct {
+	nodes     []TreeNode
+	expansion *TreeExpansion
+}
+
+// NewTreeBuilder creates a builder with expansion state
+func NewTreeBuilder(expansion *TreeExpansion) *TreeBuilder {
+	return &TreeBuilder{
+		expansion: expansion,
+	}
+}
+
+// Reset clears accumulated nodes
+func (b *TreeBuilder) Reset() {
+	b.nodes = b.nodes[:0]
+}
+
+// Add adds a node if visible (parent expanded)
+// parentExpanded should be true for root-level nodes
+func (b *TreeBuilder) Add(node TreeNode, parentExpanded bool) {
+	if !parentExpanded {
+		return
+	}
+	node.Expanded = b.expansion.IsExpanded(node.Key)
+	b.nodes = append(b.nodes, node)
+}
+
+// Nodes returns accumulated visible nodes
+func (b *TreeBuilder) Nodes() []TreeNode {
+	return b.nodes
+}
+
+// MarkLastSiblings sets IsLast flag on nodes that are last at their depth
+// Call after all nodes added, before rendering
+func (b *TreeBuilder) MarkLastSiblings() {
+	// Backward scan: seen[d] tracks whether a sibling at depth d was encountered
+	// within the current subtree. Crossing depth d invalidates deeper entries.
+	seen := make([]bool, 0, 8)
+	for i := len(b.nodes) - 1; i >= 0; i-- {
+		d := b.nodes[i].Depth
+		for len(seen) <= d {
+			seen = append(seen, false)
+		}
+		seen = seen[:d+1] // deeper entries belong to a later subtree
+		b.nodes[i].IsLast = !seen[d]
+		seen[d] = true
+	}
+}
+