flutter-quill/lib/models/rules/rule.dart

import 'package:flutter_quill/models/documents/attribute.dart';
import 'package:flutter_quill/models/documents/document.dart';
import 'package:quill_delta/quill_delta.dart';

import 'delete.dart';
import 'format.dart';
import 'insert.dart';

enum RuleType { INSERT, DELETE, FORMAT }

abstract class Rule {
  const Rule();

  Delta apply(Delta document, int index,
      {int len, Object data, Attribute attribute}) {
    assert(document != null);
    assert(index != null);
    validateArgs(len, data, attribute);
    return applyRule(document, index,
        len: len, data: data, attribute: attribute);
  }

  validateArgs(int len, Object data, Attribute attribute);

  Delta applyRule(Delta document, int index,
      {int len, Object data, Attribute attribute});

  RuleType get type;
}

class Rules {
  final List<Rule> _rules;
  static final Rules _instance = Rules([
    FormatLinkAtCaretPositionRule(),
    ResolveLineFormatRule(),
    ResolveInlineFormatRule(),
    InsertEmbedsRule(),
    ForceNewlineForInsertsAroundEmbedRule(),
    AutoExitBlockRule(),
    PreserveBlockStyleOnInsertRule(),
    PreserveLineStyleOnSplitRule(),
    ResetLineFormatOnNewLineRule(),
    AutoFormatLinksRule(),
    PreserveInlineStylesRule(),
    CatchAllInsertRule(),
    EnsureEmbedLineRule(),
    PreserveLineStyleOnMergeRule(),
    CatchAllDeleteRule(),
  ]);

  Rules(this._rules);

  static Rules getInstance() => _instance;

  Delta apply(RuleType ruleType, Document document, int index,
      {int len, Object data, Attribute attribute}) {
    Delta delta = document.toDelta();
    for (var rule in _rules) {
      if (rule.type != ruleType) {
        continue;
      }
      delta =
          rule.apply(delta, index, len: len, data: data, attribute: attribute);
      if (delta != null) {
        print("Rule $rule applied");
        return delta..trim();
      }
    }
    throw('Apply rules failed');
  }
}