lib/src/list_mutations.dart - yaml_edit - Git at Google

 // Copyright 2020 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     https://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 import 'package:yaml/yaml.dart';

 import 'editor.dart';
 import 'source_edit.dart';
 import 'strings.dart';
 import 'utils.dart';
 import 'wrap.dart';

 /// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
 /// the effect of setting the element at [index] to [newValue] when re-parsed.
 SourceEdit updateInList(
     YamlEditor yamlEdit, YamlList list, int index, YamlNode newValue) {
   ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
   ArgumentError.checkNotNull(list, 'list');
   RangeError.checkValueInInterval(index, 0, list.length - 1);

   final currValue = list.nodes[index];
   var offset = currValue.span.start.offset;
   final yaml = yamlEdit.toString();
   String valueString;

   /// We do not use [_formatNewBlock] since we want to only replace the contents
   /// of this node while preserving comments/whitespace, while [_formatNewBlock]
   /// produces a string representation of a new node.
   if (list.style == CollectionStyle.BLOCK) {
     final listIndentation = getListIndentation(yaml, list);
     final indentation = listIndentation + getIndentation(yamlEdit);
     final lineEnding = getLineEnding(yaml);
     valueString = yamlEncodeBlockString(
         wrapAsYamlNode(newValue), indentation, lineEnding);

     /// We prefer the compact nested notation for collections.
     ///
     /// By virtue of [yamlEncodeBlockString], collections automatically
     /// have the necessary line endings.
     if ((newValue is List && (newValue as List).isNotEmpty) ||
         (newValue is Map && (newValue as Map).isNotEmpty)) {
       valueString = valueString.substring(indentation);
     } else if (isCollection(currValue) &&
         getStyle(currValue) == CollectionStyle.BLOCK) {
       valueString += lineEnding;
     }

     var end = getContentSensitiveEnd(currValue);
     if (end <= offset) {
       offset++;
       end = offset;
       valueString = ' ' + valueString;
     }

     return SourceEdit(offset, end - offset, valueString);
   } else {
     valueString = yamlEncodeFlowString(newValue);
     return SourceEdit(offset, currValue.span.length, valueString);
   }
 }

 /// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
 /// the effect of appending [item] to the list.
 SourceEdit appendIntoList(YamlEditor yamlEdit, YamlList list, YamlNode item) {
   ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
   ArgumentError.checkNotNull(list, 'list');

   if (list.style == CollectionStyle.FLOW) {
     return _appendToFlowList(yamlEdit, list, item);
   } else {
     return _appendToBlockList(yamlEdit, list, item);
   }
 }

 /// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
 /// the effect of inserting [item] to the list at [index].
 SourceEdit insertInList(
     YamlEditor yamlEdit, YamlList list, int index, YamlNode item) {
   ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
   ArgumentError.checkNotNull(list, 'list');
   RangeError.checkValueInInterval(index, 0, list.length);

   /// We call the append method if the user wants to append it to the end of the
   /// list because appending requires different techniques.
   if (index == list.length) {
     return appendIntoList(yamlEdit, list, item);
   } else {
     if (list.style == CollectionStyle.FLOW) {
       return _insertInFlowList(yamlEdit, list, index, item);
     } else {
       return _insertInBlockList(yamlEdit, list, index, item);
     }
   }
 }

 /// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
 /// the effect of removing the element at [index] when re-parsed.
 SourceEdit removeInList(YamlEditor yamlEdit, YamlList list, int index) {
   ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
   ArgumentError.checkNotNull(list, 'list');

   final nodeToRemove = list.nodes[index];

   if (list.style == CollectionStyle.FLOW) {
     return _removeFromFlowList(yamlEdit, list, nodeToRemove, index);
   } else {
     return _removeFromBlockList(yamlEdit, list, nodeToRemove, index);
   }
 }

 /// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
 /// the effect of addition [item] into [nodes], noting that this is a flow list.
 SourceEdit _appendToFlowList(
     YamlEditor yamlEdit, YamlList list, YamlNode item) {
   ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
   ArgumentError.checkNotNull(list, 'list');

   final valueString = _formatNewFlow(list, item, true);
   return SourceEdit(list.span.end.offset - 1, 0, valueString);
 }

 /// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
 /// the effect of addition [item] into [nodes], noting that this is a block list.
 SourceEdit _appendToBlockList(
     YamlEditor yamlEdit, YamlList list, YamlNode item) {
   ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
   ArgumentError.checkNotNull(list, 'list');

   var formattedValue = _formatNewBlock(yamlEdit, list, item);
   final yaml = yamlEdit.toString();
   var offset = list.span.end.offset;

   // Adjusts offset to after the trailing newline of the last entry, if it exists
   if (list.isNotEmpty) {
     final lastValueSpanEnd = list.nodes.last.span.end.offset;
     final nextNewLineIndex = yaml.indexOf('\n', lastValueSpanEnd);
     if (nextNewLineIndex == -1) {
       formattedValue = getLineEnding(yaml) + formattedValue;
     } else {
       offset = nextNewLineIndex + 1;
     }
   }

   return SourceEdit(offset, 0, formattedValue);
 }

 /// Formats [item] into a new node for block lists.
 String _formatNewBlock(YamlEditor yamlEdit, YamlList list, YamlNode item) {
   ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
   ArgumentError.checkNotNull(list, 'list');

   final yaml = yamlEdit.toString();
   final listIndentation = getListIndentation(yaml, list);
   final newIndentation = listIndentation + getIndentation(yamlEdit);
   final lineEnding = getLineEnding(yaml);

   var valueString = yamlEncodeBlockString(item, newIndentation, lineEnding);
   if (isCollection(item) && !isFlowYamlCollectionNode(item) && !isEmpty(item)) {
     valueString = valueString.substring(newIndentation);
   }
   final indentedHyphen = ' ' * listIndentation + '- ';

   return '$indentedHyphen$valueString$lineEnding';
 }

 /// Formats [item] into a new node for flow lists.
 String _formatNewFlow(YamlList list, YamlNode item, [bool isLast = false]) {
   ArgumentError.checkNotNull(list, 'list');
   ArgumentError.checkNotNull(isLast, 'isLast');

   var valueString = yamlEncodeFlowString(item);
   if (list.isNotEmpty) {
     if (isLast) {
       valueString = ', $valueString';
     } else {
       valueString += ', ';
     }
   }

   return valueString;
 }

 /// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
 /// the effect of inserting [item] into [nodes] at [index], noting that this is
 /// a block list.
 ///
 /// [index] should be non-negative and less than or equal to [length].
 SourceEdit _insertInBlockList(
     YamlEditor yamlEdit, YamlList list, int index, YamlNode item) {
   ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
   ArgumentError.checkNotNull(list, 'list');
   RangeError.checkValueInInterval(index, 0, list.length);

   if (index == list.length) return _appendToBlockList(yamlEdit, list, item);

   final formattedValue = _formatNewBlock(yamlEdit, list, item);

   final currNode = list.nodes[index];
   final currNodeStart = currNode.span.start.offset;
   final yaml = yamlEdit.toString();
   final start = yaml.lastIndexOf('\n', currNodeStart) + 1;

   return SourceEdit(start, 0, formattedValue);
 }

 /// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
 /// the effect of inserting [item] into [nodes] at [index], noting that this is
 /// a flow list.
 ///
 /// [index] should be non-negative and less than or equal to [length].
 SourceEdit _insertInFlowList(
     YamlEditor yamlEdit, YamlList list, int index, YamlNode item) {
   ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
   ArgumentError.checkNotNull(list, 'list');
   RangeError.checkValueInInterval(index, 0, list.length);

   if (index == list.length) return _appendToFlowList(yamlEdit, list, item);

   final formattedValue = _formatNewFlow(list, item);

   final yaml = yamlEdit.toString();
   final currNode = list.nodes[index];
   final currNodeStart = currNode.span.start.offset;
   var start = yaml.lastIndexOf(RegExp(r',|\['), currNodeStart - 1) + 1;
   if (yaml[start] == ' ') start++;

   return SourceEdit(start, 0, formattedValue);
 }

 /// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
 /// the effect of removing [nodeToRemove] from [nodes], noting that this is a
 /// block list.
 ///
 /// [index] should be non-negative and less than or equal to [length].
 SourceEdit _removeFromBlockList(
     YamlEditor yamlEdit, YamlList list, YamlNode nodeToRemove, int index) {
   ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
   ArgumentError.checkNotNull(list, 'list');
   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 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, '');
 }

 /// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
 /// the effect of removing [nodeToRemove] from [nodes], noting that this is a
 /// flow list.
 ///
 /// [index] should be non-negative and less than or equal to [length].
 SourceEdit _removeFromFlowList(
     YamlEditor yamlEdit, YamlList list, YamlNode nodeToRemove, int index) {
   ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
   ArgumentError.checkNotNull(list, 'list');
   RangeError.checkValueInInterval(index, 0, list.length - 1);

   final span = nodeToRemove.span;
   final yaml = yamlEdit.toString();
   var start = span.start.offset;
   var end = span.end.offset;

   if (index == 0) {
     start = yaml.lastIndexOf('[', start - 1) + 1;
     if (index == list.length - 1) {
       end = yaml.indexOf(']', end);
     } else {
       end = yaml.indexOf(',', end) + 1;
     }
   } else {
     start = yaml.lastIndexOf(',', start - 1);
   }

   return SourceEdit(start, end - start, '');
 }
	// Copyright 2020 Google LLC
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// https://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	import 'package:yaml/yaml.dart';

	import 'editor.dart';
	import 'source_edit.dart';
	import 'strings.dart';
	import 'utils.dart';
	import 'wrap.dart';

	/// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
	/// the effect of setting the element at [index] to [newValue] when re-parsed.
	SourceEdit updateInList(
	YamlEditor yamlEdit, YamlList list, int index, YamlNode newValue) {
	ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
	ArgumentError.checkNotNull(list, 'list');
	RangeError.checkValueInInterval(index, 0, list.length - 1);

	final currValue = list.nodes[index];
	var offset = currValue.span.start.offset;
	final yaml = yamlEdit.toString();
	String valueString;

	/// We do not use [_formatNewBlock] since we want to only replace the contents
	/// of this node while preserving comments/whitespace, while [_formatNewBlock]
	/// produces a string representation of a new node.
	if (list.style == CollectionStyle.BLOCK) {
	final listIndentation = getListIndentation(yaml, list);
	final indentation = listIndentation + getIndentation(yamlEdit);
	final lineEnding = getLineEnding(yaml);
	valueString = yamlEncodeBlockString(
	wrapAsYamlNode(newValue), indentation, lineEnding);

	/// We prefer the compact nested notation for collections.
	///
	/// By virtue of [yamlEncodeBlockString], collections automatically
	/// have the necessary line endings.
	if ((newValue is List && (newValue as List).isNotEmpty) \|\|
	(newValue is Map && (newValue as Map).isNotEmpty)) {
	valueString = valueString.substring(indentation);
	} else if (isCollection(currValue) &&
	getStyle(currValue) == CollectionStyle.BLOCK) {
	valueString += lineEnding;
	}

	var end = getContentSensitiveEnd(currValue);
	if (end <= offset) {
	offset++;
	end = offset;
	valueString = ' ' + valueString;
	}

	return SourceEdit(offset, end - offset, valueString);
	} else {
	valueString = yamlEncodeFlowString(newValue);
	return SourceEdit(offset, currValue.span.length, valueString);
	}
	}

	/// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
	/// the effect of appending [item] to the list.
	SourceEdit appendIntoList(YamlEditor yamlEdit, YamlList list, YamlNode item) {
	ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
	ArgumentError.checkNotNull(list, 'list');

	if (list.style == CollectionStyle.FLOW) {
	return _appendToFlowList(yamlEdit, list, item);
	} else {
	return _appendToBlockList(yamlEdit, list, item);
	}
	}

	/// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
	/// the effect of inserting [item] to the list at [index].
	SourceEdit insertInList(
	YamlEditor yamlEdit, YamlList list, int index, YamlNode item) {
	ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
	ArgumentError.checkNotNull(list, 'list');
	RangeError.checkValueInInterval(index, 0, list.length);

	/// We call the append method if the user wants to append it to the end of the
	/// list because appending requires different techniques.
	if (index == list.length) {
	return appendIntoList(yamlEdit, list, item);
	} else {
	if (list.style == CollectionStyle.FLOW) {
	return _insertInFlowList(yamlEdit, list, index, item);
	} else {
	return _insertInBlockList(yamlEdit, list, index, item);
	}
	}
	}

	/// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
	/// the effect of removing the element at [index] when re-parsed.
	SourceEdit removeInList(YamlEditor yamlEdit, YamlList list, int index) {
	ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
	ArgumentError.checkNotNull(list, 'list');

	final nodeToRemove = list.nodes[index];

	if (list.style == CollectionStyle.FLOW) {
	return _removeFromFlowList(yamlEdit, list, nodeToRemove, index);
	} else {
	return _removeFromBlockList(yamlEdit, list, nodeToRemove, index);
	}
	}

	/// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
	/// the effect of addition [item] into [nodes], noting that this is a flow list.
	SourceEdit _appendToFlowList(
	YamlEditor yamlEdit, YamlList list, YamlNode item) {
	ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
	ArgumentError.checkNotNull(list, 'list');

	final valueString = _formatNewFlow(list, item, true);
	return SourceEdit(list.span.end.offset - 1, 0, valueString);
	}

	/// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
	/// the effect of addition [item] into [nodes], noting that this is a block list.
	SourceEdit _appendToBlockList(
	YamlEditor yamlEdit, YamlList list, YamlNode item) {
	ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
	ArgumentError.checkNotNull(list, 'list');

	var formattedValue = _formatNewBlock(yamlEdit, list, item);
	final yaml = yamlEdit.toString();
	var offset = list.span.end.offset;

	// Adjusts offset to after the trailing newline of the last entry, if it exists
	if (list.isNotEmpty) {
	final lastValueSpanEnd = list.nodes.last.span.end.offset;
	final nextNewLineIndex = yaml.indexOf('\n', lastValueSpanEnd);
	if (nextNewLineIndex == -1) {
	formattedValue = getLineEnding(yaml) + formattedValue;
	} else {
	offset = nextNewLineIndex + 1;
	}
	}

	return SourceEdit(offset, 0, formattedValue);
	}

	/// Formats [item] into a new node for block lists.
	String _formatNewBlock(YamlEditor yamlEdit, YamlList list, YamlNode item) {
	ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
	ArgumentError.checkNotNull(list, 'list');

	final yaml = yamlEdit.toString();
	final listIndentation = getListIndentation(yaml, list);
	final newIndentation = listIndentation + getIndentation(yamlEdit);
	final lineEnding = getLineEnding(yaml);

	var valueString = yamlEncodeBlockString(item, newIndentation, lineEnding);
	if (isCollection(item) && !isFlowYamlCollectionNode(item) && !isEmpty(item)) {
	valueString = valueString.substring(newIndentation);
	}
	final indentedHyphen = ' ' * listIndentation + '- ';

	return '$indentedHyphen$valueString$lineEnding';
	}

	/// Formats [item] into a new node for flow lists.
	String _formatNewFlow(YamlList list, YamlNode item, [bool isLast = false]) {
	ArgumentError.checkNotNull(list, 'list');
	ArgumentError.checkNotNull(isLast, 'isLast');

	var valueString = yamlEncodeFlowString(item);
	if (list.isNotEmpty) {
	if (isLast) {
	valueString = ', $valueString';
	} else {
	valueString += ', ';
	}
	}

	return valueString;
	}

	/// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
	/// the effect of inserting [item] into [nodes] at [index], noting that this is
	/// a block list.
	///
	/// [index] should be non-negative and less than or equal to [length].
	SourceEdit _insertInBlockList(
	YamlEditor yamlEdit, YamlList list, int index, YamlNode item) {
	ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
	ArgumentError.checkNotNull(list, 'list');
	RangeError.checkValueInInterval(index, 0, list.length);

	if (index == list.length) return _appendToBlockList(yamlEdit, list, item);

	final formattedValue = _formatNewBlock(yamlEdit, list, item);

	final currNode = list.nodes[index];
	final currNodeStart = currNode.span.start.offset;
	final yaml = yamlEdit.toString();
	final start = yaml.lastIndexOf('\n', currNodeStart) + 1;

	return SourceEdit(start, 0, formattedValue);
	}

	/// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
	/// the effect of inserting [item] into [nodes] at [index], noting that this is
	/// a flow list.
	///
	/// [index] should be non-negative and less than or equal to [length].
	SourceEdit _insertInFlowList(
	YamlEditor yamlEdit, YamlList list, int index, YamlNode item) {
	ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
	ArgumentError.checkNotNull(list, 'list');
	RangeError.checkValueInInterval(index, 0, list.length);

	if (index == list.length) return _appendToFlowList(yamlEdit, list, item);

	final formattedValue = _formatNewFlow(list, item);

	final yaml = yamlEdit.toString();
	final currNode = list.nodes[index];
	final currNodeStart = currNode.span.start.offset;
	var start = yaml.lastIndexOf(RegExp(r',\|\['), currNodeStart - 1) + 1;
	if (yaml[start] == ' ') start++;

	return SourceEdit(start, 0, formattedValue);
	}

	/// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
	/// the effect of removing [nodeToRemove] from [nodes], noting that this is a
	/// block list.
	///
	/// [index] should be non-negative and less than or equal to [length].
	SourceEdit _removeFromBlockList(
	YamlEditor yamlEdit, YamlList list, YamlNode nodeToRemove, int index) {
	ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
	ArgumentError.checkNotNull(list, 'list');
	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 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, '');
	}

	/// Returns a [SourceEdit] describing the change to be made on [yaml] to achieve
	/// the effect of removing [nodeToRemove] from [nodes], noting that this is a
	/// flow list.
	///
	/// [index] should be non-negative and less than or equal to [length].
	SourceEdit _removeFromFlowList(
	YamlEditor yamlEdit, YamlList list, YamlNode nodeToRemove, int index) {
	ArgumentError.checkNotNull(yamlEdit, 'yamlEdit');
	ArgumentError.checkNotNull(list, 'list');
	RangeError.checkValueInInterval(index, 0, list.length - 1);

	final span = nodeToRemove.span;
	final yaml = yamlEdit.toString();
	var start = span.start.offset;
	var end = span.end.offset;

	if (index == 0) {
	start = yaml.lastIndexOf('[', start - 1) + 1;
	if (index == list.length - 1) {
	end = yaml.indexOf(']', end);
	} else {
	end = yaml.indexOf(',', end) + 1;
	}
	} else {
	start = yaml.lastIndexOf(',', start - 1);
	}

	return SourceEdit(start, end - start, '');
	}