Snapshot/signal value format registry

packages/rohd_hierarchy/lib/src/hierarchy_models.dart

@@ -12,5 +12,6 @@ export 'hierarchy_occurrence.dart';
 export 'hierarchy_search_result.dart';
 export 'occurrence_address.dart';
 export 'occurrence_search_result.dart';
+export 'occurrence_trie.dart';
 export 'signal_occurrence.dart';
 export 'signal_search_result.dart';

packages/rohd_hierarchy/lib/src/occurrence_trie.dart

@@ -0,0 +1,104 @@
+// Copyright (C) 2026 Intel Corporation
+// SPDX-License-Identifier: BSD-3-Clause
+//
+// occurrence_trie.dart
+// Compact storage for values keyed by hierarchy occurrence addresses.
+//
+// 2026 August
+// Author: Desmond Kirkpatrick <desmond.a.kirkpatrick@intel.com>
+
+import 'package:rohd_hierarchy/src/occurrence_address.dart';
+
+/// A prefix-sharing map from [OccurrenceAddress] values to values of type [T].
+///
+/// Common address prefixes are stored once, making this more compact than a
+/// conventional map when many values belong to the same hierarchy subtree.
+class OccurrenceTrie<T extends Object> {
+  /// The root node, which represents [OccurrenceAddress.root].
+  final _OccurrenceTrieNode<T> _root = _OccurrenceTrieNode<T>();
+
+  /// Whether this trie contains no values.
+  bool get isEmpty => _root.isEmpty;
+
+  /// The value stored at [address], if any.
+  T? operator [](OccurrenceAddress address) {
+    var node = _root;
+    for (final index in _validatedPath(address)) {
+      final child = node.children[index];
+      if (child == null) {
+        return null;
+      }
+      node = child;
+    }
+    return node.value;
+  }
+
+  /// Associates [value] with [address].
+  void operator []=(OccurrenceAddress address, T value) {
+    var node = _root;
+    for (final index in _validatedPath(address)) {
+      node = node.children.putIfAbsent(index, _OccurrenceTrieNode<T>.new);
+    }
+    node.value = value;
+  }
+
+  /// Removes and returns the value stored at [address], if any.
+  T? remove(OccurrenceAddress address) {
+    final path = _validatedPath(address);
+    final nodes = <_OccurrenceTrieNode<T>>[_root];
+    var node = _root;
+    for (final index in path) {
+      final child = node.children[index];
+      if (child == null) {
+        return null;
+      }
+      nodes.add(child);
+      node = child;
+    }
+
+    final previous = node.value;
+    if (previous == null) {
+      return null;
+    }
+    node.value = null;
+    for (var index = path.length - 1; index >= 0; index--) {
+      final child = nodes[index + 1];
+      if (!child.isEmpty) {
+        break;
+      }
+      nodes[index].children.remove(path[index]);
+    }
+    return previous;
+  }
+
+  /// Removes every value from this trie.
+  void clear() {
+    _root
+      ..value = null
+      ..children.clear();
+  }
+
+  /// Returns [address]'s valid, non-negative path.
+  static List<int> _validatedPath(OccurrenceAddress address) {
+    if (address.path.any((index) => index < 0)) {
+      throw ArgumentError.value(
+        address,
+        'address',
+        'An occurrence address must contain non-negative indices.',
+      );
+    }
+    return address.path;
+  }
+}
+
+/// A node in an [OccurrenceTrie].
+class _OccurrenceTrieNode<T extends Object> {
+  /// Descendants indexed by their address path component.
+  final Map<int, _OccurrenceTrieNode<T>> children = {};
+
+  /// The value stored at this node, if one has been assigned.
+  T? value;
+
+  /// Whether this node has neither a value nor descendants.
+  bool get isEmpty => value == null && children.isEmpty;
+}

packages/rohd_hierarchy/test/occurrence_trie_test.dart

@@ -0,0 +1,53 @@
+// Copyright (C) 2026 Intel Corporation
+// SPDX-License-Identifier: BSD-3-Clause
+//
+// occurrence_trie_test.dart
+// Tests for compact occurrence-address trie storage.
+//
+// 2026 August
+// Author: Desmond Kirkpatrick <desmond.a.kirkpatrick@intel.com>
+
+import 'package:rohd_hierarchy/rohd_hierarchy.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('stores values with shared occurrence-address prefixes', () {
+    final trie = OccurrenceTrie<String>();
+    const first = OccurrenceAddress([0, 2, 4]);
+    const second = OccurrenceAddress([0, 2, 5]);
+
+    trie[first] = 'first';
+    trie[OccurrenceAddress.root] = 'root';
+    trie[second] = 'second';
+
+    expect(trie[OccurrenceAddress.root], 'root');
+    expect(trie[first], 'first');
+    expect(trie[second], 'second');
+    expect(trie[const OccurrenceAddress([0, 2, 6])], isNull);
+  });
+
+  test('prunes an address branch after removing its final value', () {
+    final trie = OccurrenceTrie<String>();
+    const first = OccurrenceAddress([0, 2, 4]);
+    const second = OccurrenceAddress([0, 2, 5]);
+    trie[first] = 'first';
+    trie[second] = 'second';
+
+    expect(trie.remove(first), 'first');
+    expect(trie[first], isNull);
+    expect(trie[second], 'second');
+    expect(trie.remove(second), 'second');
+    expect(trie.isEmpty, isTrue);
+  });
+
+  test('accepts root addresses and rejects negative path indices', () {
+    final trie = OccurrenceTrie<String>();
+
+    trie[OccurrenceAddress.root] = 'root';
+    expect(trie[OccurrenceAddress.root], 'root');
+    expect(
+      () => trie[const OccurrenceAddress([0, -1])],
+      throwsArgumentError,
+    );
+  });
+}

rohd_devtools_extension/packages/rohd_devtools_widgets/README.md

@@ -26,6 +26,48 @@ across DevTools packages.
 - ROHD extension client/status abstractions: `RohdExtensionClient`,
  `NullExtensionClient`, `RohdModuleInfo`, and `RohdFormatInfo`.
 
+## Widgets & Utilities
+
+### UI Controls & Buttons
+
+- **`MarkdownHelpButton`** — A help button that displays Markdown content from an asset file in a dialog. Supports tooltip text and rich formatting.
+
+- **`ExportPngButton`** — A camera icon button for triggering PNG export functionality. Includes customizable tooltip text.
+
+- **`CrossProbeButton`** — A toolbar button for toggling cross-probing between viewers. Shows a bidirectional arrows icon that reflects the active/inactive state.
+
+### Overlays & Layout
+
+- **`AppBarOverlay`** — An auto-hiding AppBar that slides in from the top edge when the mouse approaches. When disabled, behaves like a standard AppBar.
+
+### Export & Capture
+
+- **`captureBoundaryToPng`** — Captures a `RepaintBoundary` as PNG and saves or downloads it.
+
+- **`showExportToast`** — Shows export feedback and status messages.
+
+### Cross-Probing
+
+- **`CrossProbeService`** — Service for managing cross-probe state between multiple viewers/debuggers. Handles bidirectional signal selection synchronization.
+
+- **`buildGotoSourceMenuItems`** — Builds source-navigation menu items for ROHD DevTools surfaces.
+
+### Signal & Bit Field Utilities
+
+- **`expandLogicType`**, **`formatFieldValue`**, and **`formatTypeTooltip`** — Format ROHD logic types and values for display.
+
+- **`BitFieldDef`**, **`showBitRangeDialog`**, and **`showDefineBitFieldsDialog`** — Define and edit bit-field ranges.
+
+- **`buildBitExpansionMenuItems`** and **`resolveBitExpansionMenuValue`** — Build and resolve the "Expand Bits" and "Define Bit Fields" actions used across signal selection overlays and panels.
+
+- **`SignalValueFormatRegistry`** — Shared registry for signal display-format preferences, allowing consistent formatting across multiple viewers.
+
+### Extension Integration
+
+- **`RohdExtensionClient`** — Abstract interface for querying the ROHD VS Code extension. Supports multiple implementations (DevTools, VS Code webview, offline mode).
+
+- **`RohdSourceFormat`** and **`RohdFormatInfo`** — Describe source formats and their availability.
+
 ## Usage
 
 Add this package as a path dependency from a ROHD DevTools package and import the shared widgets you need:

rohd_devtools_extension/packages/rohd_devtools_widgets/lib/rohd_devtools_widgets.dart

@@ -36,6 +36,9 @@ export 'src/bit_field_utils.dart';
 // Shared "Expand Bits" / "Define Bit Fields" popup-menu helpers
 export 'src/bit_expansion_menu.dart';
 
+// Shared signal display-format preferences and value formatting
+export 'src/signal_value_format_registry.dart';
+
 // ROHD extension client
 export 'src/rohd_extension_status.dart';
 export 'src/rohd_extension_client.dart';