Prevent YamlEditor.remove from affecting existing block scalars

* Refactor `_removeFromBlockList` and `_removeFromBlockMap` and remove dangling line breaks which may affect how block scalars are intepreted by the `package: yaml`.
* Prefer obtaining an entry in one pass from `YamlMap`.
* Add tests

Author: kekavc24

pkgs/yaml_edit/lib/src/equality.dart

@@ -91,6 +91,20 @@ YamlNode getKeyNode(YamlMap map, Object? key) {
   return map.nodes.keys.firstWhere((node) => deepEquals(node, key)) as YamlNode;
 }
 
+/// Returns the entry associated with a [mapKey] and its index in the [map].
+({int index, YamlNode keyNode, YamlNode valueNode}) getYamlMapEntry(
+  YamlMap map,
+  Object? mapKey,
+) {
+  for (final (index, MapEntry(:key, :value)) in map.nodes.entries.indexed) {
+    if (deepEquals(key, mapKey)) {
+      return (index: index, keyNode: key, valueNode: value);
+    }
+  }
+
+  throw YamlException('$mapKey not found in map', map.span);
+}
+
 /// Returns the [YamlNode] after the [YamlNode] corresponding to the provided
 /// [key].
 YamlNode? getNextKeyNode(YamlMap map, Object? key) {

pkgs/yaml_edit/lib/src/list_mutations.dart

@@ -306,72 +306,43 @@ SourceEdit _insertInFlowList(
 /// [index] should be non-negative and less than or equal to `list.length`.
 SourceEdit _removeFromBlockList(
     YamlEditor yamlEdit, YamlList list, YamlNode nodeToRemove, int index) {
-  RangeError.checkValueInInterval(index, 0, list.length - 1);
-
-  var end = getContentSensitiveEnd(nodeToRemove);
-
-  /// If we are removing the last element in a block list, convert it into a
-  /// flow empty list.
-  if (list.length == 1) {
-    final start = list.span.start.offset;
-
-    return SourceEdit(start, end - start, '[]');
-  }
+  final listSize = list.length;
+  RangeError.checkValueInInterval(index, 0, listSize - 1);
 
   final yaml = yamlEdit.toString();
   final span = nodeToRemove.span;
 
-  /// Adjust the end to clear the new line after the end too.
-  ///
-  /// We do this because we suspect that our users will want the inline
-  /// comments to disappear too.
-  final nextNewLine = yaml.indexOf('\n', end);
-  if (nextNewLine != -1) {
-    end = nextNewLine + 1;
-  }
-
-  /// If the value is empty
-  if (span.length == 0) {
-    var start = span.start.offset;
-    return SourceEdit(start, end - start, '');
-  }
-
-  /// -1 accounts for the fact that the content can start with a dash
-  var start = yaml.lastIndexOf('-', span.start.offset - 1);
-
-  /// Check if there is a `-` before the node
-  if (start > 0) {
-    final lastHyphen = yaml.lastIndexOf('-', start - 1);
-    final lastNewLine = yaml.lastIndexOf('\n', start - 1);
-    if (lastHyphen > lastNewLine) {
-      start = lastHyphen + 2;
-
-      /// If there is a `-` before the node, we need to check if we have
-      /// to update the indentation of the next node.
-      if (index < list.length - 1) {
-        /// Since [end] is currently set to the next new line after the current
-        /// node, check if we see a possible comment first, or a hyphen first.
-        /// Note that no actual content can appear here.
-        ///
-        /// We check this way because the start of a span in a block list is
-        /// the start of its value, and checking from the back leaves us
-        /// easily confused if there are comments that have dashes in them.
-        final nextHash = yaml.indexOf('#', end);
-        final nextHyphen = yaml.indexOf('-', end);
-        final nextNewLine = yaml.indexOf('\n', end);
-
-        /// If [end] is on the same line as the hyphen of the next node
-        if ((nextHash == -1 || nextHyphen < nextHash) &&
-            nextHyphen < nextNewLine) {
-          end = nextHyphen;
-        }
-      }
-    } else if (lastNewLine > lastHyphen) {
-      start = lastNewLine + 1;
-    }
-  }
-
-  return SourceEdit(start, end - start, '');
+  return removeBlockCollectionEntry(
+    yaml,
+    blockCollection: list,
+    isFirstEntry: index == 0,
+    isSingleEntry: listSize == 1,
+    isLastEntry: index >= listSize - 1,
+    nodeToRemoveOffset: (
+      start: span.length == 0
+          ? span.start.offset
+          : yaml.lastIndexOf('-', span.start.offset - 1),
+      end: getContentSensitiveEnd(nodeToRemove)
+    ),
+    lineEnding: getLineEnding(yaml),
+    nextBlockNodeInfo: () {
+      final nextNode = list.nodes[index + 1];
+      final nextNodeSpan = nextNode.span;
+      final offset = nextNodeSpan.start.offset;
+
+      final hyphenOffset = yaml.lastIndexOf(
+        '-',
+        span.length == 0 ? offset : offset - 1,
+      );
+
+      final nearestLineEnding = yaml.lastIndexOf('\n', hyphenOffset);
+
+      return (
+        nearestLineEnding: nearestLineEnding,
+        nextNodeColStart: hyphenOffset - (nearestLineEnding + 1),
+      );
+    },
+  );
 }
 
 /// Returns a [SourceEdit] describing the change to be made on [yamlEdit] to

pkgs/yaml_edit/lib/src/map_mutations.dart

@@ -36,13 +36,11 @@ SourceEdit updateInMap(
 /// removing the element at [key] when re-parsed.
 SourceEdit removeInMap(YamlEditor yamlEdit, YamlMap map, Object? key) {
   assert(containsKey(map, key));
-  final keyNode = getKeyNode(map, key);
-  final valueNode = map.nodes[keyNode]!;
 
   if (map.style == CollectionStyle.FLOW) {
-    return _removeFromFlowMap(yamlEdit, map, keyNode, valueNode);
+    return _removeFromFlowMap(yamlEdit, map, key);
   } else {
-    return _removeFromBlockMap(yamlEdit, map, keyNode, valueNode);
+    return _removeFromBlockMap(yamlEdit, map, key);
   }
 }
 
@@ -169,74 +167,47 @@ SourceEdit _replaceInFlowMap(
 }
 
 /// Performs the string operation on [yamlEdit] to achieve the effect of
-/// removing the [keyNode] from the map, bearing in mind that this is a block
+/// removing the [key] from the map, bearing in mind that this is a block
 /// map.
-SourceEdit _removeFromBlockMap(
-    YamlEditor yamlEdit, YamlMap map, YamlNode keyNode, YamlNode valueNode) {
-  final keySpan = keyNode.span;
-  var end = getContentSensitiveEnd(valueNode);
+SourceEdit _removeFromBlockMap(YamlEditor yamlEdit, YamlMap map, Object? key) {
+  final (index: entryIndex, :keyNode, :valueNode) = getYamlMapEntry(map, key);
   final yaml = yamlEdit.toString();
-  final lineEnding = getLineEnding(yaml);
-
-  if (map.length == 1) {
-    final start = map.span.start.offset;
-    final nextNewLine = yaml.indexOf(lineEnding, end);
-    if (nextNewLine != -1) {
-      // Remove everything up to the next newline, this strips comments that
-      // follows on the same line as the value we're removing.
-      // It also ensures we consume colon when [valueNode.value] is `null`
-      // because there is no value (e.g. `key: \n`). Because [valueNode.span] in
-      // such cases point to the colon `:`.
-      end = nextNewLine;
-    } else {
-      // Remove everything until the end of the document, if there is no newline
-      end = yaml.length;
-    }
-    return SourceEdit(start, end - start, '{}');
-  }
-
-  var start = keySpan.start.offset;
-
-  /// Adjust the end to clear the new line after the end too.
-  ///
-  /// We do this because we suspect that our users will want the inline
-  /// comments to disappear too.
-  final nextNewLine = yaml.indexOf(lineEnding, end);
-  if (nextNewLine != -1) {
-    end = nextNewLine + lineEnding.length;
-  } else {
-    // Remove everything until the end of the document, if there is no newline
-    end = yaml.length;
-  }
-
-  final nextNode = getNextKeyNode(map, keyNode);
-
-  if (start > 0) {
-    final lastHyphen = yaml.lastIndexOf('-', start - 1);
-    final lastNewLine = yaml.lastIndexOf(lineEnding, start - 1);
-    if (lastHyphen > lastNewLine) {
-      start = lastHyphen + 2;
-
-      /// If there is a `-` before the node, and the end is on the same line
-      /// as the next node, we need to add the necessary offset to the end to
-      /// make sure the next node has the correct indentation.
-      if (nextNode != null &&
-          nextNode.span.start.offset - end <= nextNode.span.start.column) {
-        end += nextNode.span.start.column;
-      }
-    } else if (lastNewLine > lastHyphen) {
-      start = lastNewLine + lineEnding.length;
-    }
-  }
+  final mapSize = map.length;
+  final keySpan = keyNode.span;
 
-  return SourceEdit(start, end - start, '');
+  return removeBlockCollectionEntry(
+    yaml,
+    blockCollection: map,
+    isFirstEntry: entryIndex == 0,
+    isSingleEntry: mapSize == 1,
+    isLastEntry: entryIndex >= mapSize - 1,
+    nodeToRemoveOffset: (
+      start: keySpan.start.offset,
+      end: valueNode.span.length == 0
+          ? keySpan.end.offset + 2 // Null value have no span. Skip ":".
+          : getContentSensitiveEnd(valueNode),
+    ),
+    lineEnding: getLineEnding(yaml),
+
+    // Only called when the next node is present. Never before.
+    nextBlockNodeInfo: () {
+      final nextKeyNode = map.nodes.keys.elementAt(entryIndex + 1) as YamlNode;
+      final nextKeySpan = nextKeyNode.span.start;
+
+      return (
+        nearestLineEnding: yaml.lastIndexOf('\n', nextKeySpan.offset),
+        nextNodeColStart: nextKeySpan.column
+      );
+    },
+  );
 }
 
 /// Performs the string operation on [yamlEdit] to achieve the effect of
-/// removing the [keyNode] from the map, bearing in mind that this is a flow
+/// removing the [key] from the map, bearing in mind that this is a flow
 /// map.
-SourceEdit _removeFromFlowMap(
-    YamlEditor yamlEdit, YamlMap map, YamlNode keyNode, YamlNode valueNode) {
+SourceEdit _removeFromFlowMap(YamlEditor yamlEdit, YamlMap map, Object? key) {
+  final (index: _, :keyNode, :valueNode) = getYamlMapEntry(map, key);
+
   var start = keyNode.span.start.offset;
   var end = valueNode.span.end.offset;
   final yaml = yamlEdit.toString();