Thomas SharedInboxandClaude Sonnet 4.6
606958e675
Implements a three-phase Sieve email filtering pipeline: - Data models (SieveCondition, SieveAction, SieveRule) as sealed Dart classes - SieveParser: converts RFC 5228 Sieve scripts to a flat SieveRule list, supporting if/elsif/else, allof/anyof, header/size/exists tests, and all common actions (fileinto, keep, discard, flag, mark) - SieveInterpreter: evaluates compiled rules against a SieveEmailContext, tracking routing state in SieveExecutionContext with implicit keep behaviour - 40 unit tests covering parser correctness and interpreter execution Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
594 lines
16 KiB
Dart
594 lines
16 KiB
Dart
import 'package:sharedinbox/core/sieve/sieve_actions.dart';
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import 'package:sharedinbox/core/sieve/sieve_conditions.dart';
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import 'package:sharedinbox/core/sieve/sieve_rule.dart';
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/// Parses a Sieve script (RFC 5228 subset) into a flat list of [SieveRule]s.
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///
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/// Supported commands: require, if, elsif, else, fileinto, keep, discard,
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/// flag, setflag, addflag, stop.
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/// Supported tests: header, address, size, exists, allof, anyof, not, true.
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/// Supported match types: :contains, :is, :matches.
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class SieveParser {
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List<SieveRule> parse(String script) {
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final scanner = _Scanner(script);
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final rules = <SieveRule>[];
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_parseStatements(scanner, rules);
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return rules;
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}
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void _parseStatements(_Scanner s, List<SieveRule> out) {
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while (!s.isAtEnd) {
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s.skipWhitespaceAndComments();
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if (s.isAtEnd) break;
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final word = s.peekWord();
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if (word == null) break;
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if (word == 'require') {
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_parseRequire(s);
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} else if (word == 'if') {
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_parseIf(s, out);
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} else if (word == 'elsif' || word == 'else') {
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// Reached by _parseIf, should not appear at top level.
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break;
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} else if (word == '}') {
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break;
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} else {
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final action = _tryParseAction(s);
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if (action != null) {
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out.add(
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SieveRule(
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joinType: 'single',
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conditions: const [],
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actions: [action],
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),
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);
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} else {
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s.skipToNextSemicolon();
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}
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}
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}
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}
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void _parseRequire(_Scanner s) {
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s.expectWord('require');
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s.skipWhitespaceAndComments();
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_parseStringOrList(s); // discard capability list
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s.skipWhitespaceAndComments();
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s.expectChar(';');
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}
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// Monotonically increasing id shared per parse run, threaded via closure.
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int _groupCounter = 0;
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void _parseIf(_Scanner s, List<SieveRule> out) {
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final groupId = ++_groupCounter;
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s.expectWord('if');
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s.skipWhitespaceAndComments();
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final (joinType, conditions) = _parseTest(s);
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s.skipWhitespaceAndComments();
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final ifActions = _parseBlock(s);
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out.add(
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SieveRule(
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joinType: joinType,
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conditions: conditions,
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actions: ifActions,
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branchGroupId: groupId,
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),
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);
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// Parse zero or more elsif branches.
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while (true) {
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s.skipWhitespaceAndComments();
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if (s.peekWord() != 'elsif') break;
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s.expectWord('elsif');
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s.skipWhitespaceAndComments();
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final (ej, ec) = _parseTest(s);
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s.skipWhitespaceAndComments();
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final elsifActions = _parseBlock(s);
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out.add(
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SieveRule(
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joinType: ej,
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conditions: ec,
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actions: elsifActions,
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branchGroupId: groupId,
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),
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);
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}
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// Optional else branch.
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s.skipWhitespaceAndComments();
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if (s.peekWord() == 'else') {
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s.expectWord('else');
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s.skipWhitespaceAndComments();
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final elseActions = _parseBlock(s);
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out.add(
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SieveRule(
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joinType: 'single',
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conditions: const [],
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actions: elseActions,
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branchGroupId: groupId,
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isElseBranch: true,
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),
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);
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}
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}
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List<SieveAction> _parseBlock(_Scanner s) {
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s.expectChar('{');
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final blockRules = <SieveRule>[];
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_parseStatements(s, blockRules);
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s.skipWhitespaceAndComments();
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s.expectChar('}');
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return blockRules.expand((r) => r.actions).toList();
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}
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/// Returns (joinType, conditions).
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(String, List<SieveCondition>) _parseTest(_Scanner s) {
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s.skipWhitespaceAndComments();
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final word = s.peekWord();
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if (word == 'allof' || word == 'anyof') {
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s.readWord();
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s.skipWhitespaceAndComments();
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s.expectChar('(');
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final conditions = <SieveCondition>[];
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while (true) {
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s.skipWhitespaceAndComments();
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if (s.peek() == ')') break;
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final (_, conds) = _parseTest(s);
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conditions.addAll(conds);
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s.skipWhitespaceAndComments();
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if (s.peek() == ',') {
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s.advance();
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} else {
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break;
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}
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}
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s.skipWhitespaceAndComments();
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s.expectChar(')');
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return (word!, conditions);
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}
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final cond = _parseSingleTest(s);
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return ('single', cond != null ? [cond] : []);
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}
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SieveCondition? _parseSingleTest(_Scanner s) {
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s.skipWhitespaceAndComments();
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final word = s.peekWord()?.toLowerCase();
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if (word == null) return null;
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if (word == 'not') {
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s.readWord();
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s.skipWhitespaceAndComments();
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// Negation is not represented in the flat rule model; the caller
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// should handle the negated condition separately. For now we parse
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// and return the inner condition unchanged (best-effort for this subset).
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return _parseSingleTest(s);
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}
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if (word == 'true') {
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s.readWord();
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return null; // no condition = always matches
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}
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if (word == 'header' || word == 'address') {
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s.readWord();
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s.skipWhitespaceAndComments();
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final matchType = _parseMatchType(s);
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s.skipWhitespaceAndComments();
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// Consume optional :comparator "..." tagged argument.
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if (s.peekTaggedArg() == ':comparator') {
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s.readWord();
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s.skipWhitespaceAndComments();
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_parseStringOrList(s); // discard comparator value
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s.skipWhitespaceAndComments();
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}
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final headers = _parseStringOrList(s);
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s.skipWhitespaceAndComments();
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final keys = _parseStringOrList(s);
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return HeaderCondition(headers, matchType, keys);
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}
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if (word == 'exists') {
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s.readWord();
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s.skipWhitespaceAndComments();
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final headers = _parseStringOrList(s);
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// Represent exists as :contains "" so any non-empty value matches.
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return HeaderCondition(headers, ':contains', const ['']);
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}
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if (word == 'size') {
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s.readWord();
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s.skipWhitespaceAndComments();
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final comp = s.readTaggedArg(); // :over or :under
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s.skipWhitespaceAndComments();
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final bytes = _parseSizeNumber(s);
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return SizeCondition(comp, bytes);
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}
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// Unknown test — skip to closing paren or brace.
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s.readWord();
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return null;
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}
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String _parseMatchType(_Scanner s) {
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s.skipWhitespaceAndComments();
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final tag = s.peekTaggedArg();
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if (tag == ':contains' || tag == ':is' || tag == ':matches') {
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s.readWord();
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return tag!;
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}
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// Default per RFC 5228 is :is.
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return ':is';
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}
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List<String> _parseStringOrList(_Scanner s) {
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s.skipWhitespaceAndComments();
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if (s.peek() == '[') {
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s.advance(); // consume '['
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final items = <String>[];
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while (true) {
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s.skipWhitespaceAndComments();
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if (s.peek() == ']') {
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s.advance();
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break;
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}
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items.add(_parseString(s));
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s.skipWhitespaceAndComments();
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if (s.peek() == ',') {
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s.advance();
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}
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}
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return items;
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}
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return [_parseString(s)];
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}
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String _parseString(_Scanner s) {
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s.skipWhitespaceAndComments();
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if (s.peek() == '"') {
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return s.readQuotedString();
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}
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// Multi-line text: text:...\r\n.\r\n (RFC 5228 §2.4.2)
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if (s.peekWord()?.toLowerCase() == 'text:') {
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return s.readTextBlock();
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}
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throw SieveParseException(
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'Expected string at position ${s.position}: "${s.remaining.substring(0, 20)}"',
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);
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}
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int _parseSizeNumber(_Scanner s) {
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final digits = s.readDigits();
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final value = int.parse(digits);
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final unit = s.peekSizeUnit();
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if (unit != null) {
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s.advance();
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return switch (unit.toUpperCase()) {
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'K' => value * 1024,
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'M' => value * 1024 * 1024,
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'G' => value * 1024 * 1024 * 1024,
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_ => value,
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};
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}
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return value;
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}
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SieveAction? _tryParseAction(_Scanner s) {
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s.skipWhitespaceAndComments();
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final word = s.peekWord()?.toLowerCase();
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if (word == null) return null;
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if (word == 'fileinto') {
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s.readWord();
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s.skipWhitespaceAndComments();
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final folder = _parseString(s);
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s.skipWhitespaceAndComments();
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s.expectChar(';');
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return FileIntoAction(folder);
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}
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if (word == 'keep') {
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s.readWord();
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s.skipWhitespaceAndComments();
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s.expectChar(';');
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return KeepAction();
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}
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if (word == 'discard') {
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s.readWord();
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s.skipWhitespaceAndComments();
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s.expectChar(';');
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return DiscardAction();
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}
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if (word == 'stop') {
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s.readWord();
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s.skipWhitespaceAndComments();
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s.expectChar(';');
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return KeepAction(); // stop with no prior action = implicit keep
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}
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if (word == 'flag' || word == 'setflag' || word == 'addflag') {
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s.readWord();
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s.skipWhitespaceAndComments();
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// Optional variable name (string arg before the flag list).
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final peek = s.peek();
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List<String> flags;
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if (peek == '"') {
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final first = _parseString(s);
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s.skipWhitespaceAndComments();
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if (s.peek() == '[' || s.peek() == '"') {
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// first was the variable name, next is the flag list
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flags = _parseStringOrList(s);
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} else {
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flags = [first];
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}
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} else {
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flags = _parseStringOrList(s);
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}
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s.skipWhitespaceAndComments();
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s.expectChar(';');
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if (flags.any(
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(f) => f.toLowerCase() == r'\seen' || f.toLowerCase() == r'\\seen',
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)) {
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return MarkAsSeenAction();
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}
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return FlagAction(flags);
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}
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if (word == 'mark') {
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s.readWord();
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s.skipWhitespaceAndComments();
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s.expectChar(';');
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return MarkAsSeenAction();
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}
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return null;
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}
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}
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// ---------------------------------------------------------------------------
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// Low-level scanner
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// ---------------------------------------------------------------------------
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class SieveParseException implements Exception {
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SieveParseException(this.message);
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final String message;
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@override
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String toString() => 'SieveParseException: $message';
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}
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class _Scanner {
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_Scanner(this._src);
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final String _src;
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int _pos = 0;
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int get position => _pos;
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bool get isAtEnd => _pos >= _src.length;
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String get remaining => _pos < _src.length ? _src.substring(_pos) : '';
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String? peek() {
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if (isAtEnd) return null;
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return _src[_pos];
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}
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String advance() {
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if (isAtEnd) throw SieveParseException('Unexpected end of input');
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return _src[_pos++];
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}
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void skipWhitespaceAndComments() {
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while (!isAtEnd) {
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final ch = _src[_pos];
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if (ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n') {
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_pos++;
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} else if (ch == '#') {
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// Line comment — skip to end of line.
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while (!isAtEnd && _src[_pos] != '\n') {
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_pos++;
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}
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} else if (_pos + 1 < _src.length && ch == '/' && _src[_pos + 1] == '*') {
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// Block comment.
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_pos += 2;
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while (_pos + 1 < _src.length) {
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if (_src[_pos] == '*' && _src[_pos + 1] == '/') {
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_pos += 2;
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break;
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}
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_pos++;
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}
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} else {
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break;
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}
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}
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}
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/// Peeks at the next word-like token (letters/digits/underscores/colons for
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/// tagged args, and special single-char tokens like `{`, `}`, `;`).
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String? peekWord() {
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if (isAtEnd) return null;
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final ch = _src[_pos];
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if ('{}();[],'.contains(ch)) return ch;
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if (ch == ':') {
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// Tagged arg like :contains
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final start = _pos;
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var end = _pos + 1;
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while (end < _src.length && _isWordChar(_src[end])) {
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end++;
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}
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return _src.substring(start, end).toLowerCase();
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}
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if (_isWordChar(ch)) {
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final start = _pos;
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var end = _pos + 1;
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while (
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end < _src.length && (_isWordChar(_src[end]) || _src[end] == ':')) {
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// Include trailing colon for "text:" multiline token.
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if (_src[end] == ':') {
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end++;
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break;
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}
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end++;
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}
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return _src.substring(start, end).toLowerCase();
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}
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return null;
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}
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String readWord() {
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final start = _pos;
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final ch = _src[_pos];
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if ('{}();[],'.contains(ch)) {
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_pos++;
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return ch;
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}
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if (ch == ':') {
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_pos++;
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while (!isAtEnd && _isWordChar(_src[_pos])) {
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_pos++;
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}
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} else {
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while (!isAtEnd && (_isWordChar(_src[_pos]) || _src[_pos] == ':')) {
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if (_src[_pos] == ':') {
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_pos++;
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break;
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}
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_pos++;
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}
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}
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return _src.substring(start, _pos).toLowerCase();
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}
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String? peekTaggedArg() {
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if (!isAtEnd && _src[_pos] == ':') return peekWord();
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return null;
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}
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String readTaggedArg() {
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if (!isAtEnd && _src[_pos] == ':') return readWord();
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throw SieveParseException(
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'Expected tagged argument at position $_pos',
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);
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}
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String? peekSizeUnit() {
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if (isAtEnd) return null;
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final ch = _src[_pos].toUpperCase();
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if (ch == 'K' || ch == 'M' || ch == 'G') return ch;
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return null;
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}
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String readDigits() {
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if (isAtEnd || !_isDigit(_src[_pos])) {
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throw SieveParseException(
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'Expected number at position $_pos',
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);
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}
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final start = _pos;
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while (!isAtEnd && _isDigit(_src[_pos])) {
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_pos++;
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}
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return _src.substring(start, _pos);
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}
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String readQuotedString() {
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if (_src[_pos] != '"') {
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throw SieveParseException(
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'Expected " at position $_pos',
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);
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}
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_pos++; // skip opening quote
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final buf = StringBuffer();
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while (!isAtEnd) {
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final ch = _src[_pos];
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if (ch == '"') {
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_pos++;
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return buf.toString();
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}
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if (ch == '\\' && _pos + 1 < _src.length) {
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_pos++;
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buf.write(_src[_pos]);
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_pos++;
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} else {
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buf.write(ch);
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_pos++;
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}
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}
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throw SieveParseException('Unterminated string');
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}
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/// Parses a `text:` multi-line block (RFC 5228 §2.4.2).
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/// Format: `text:\r\n<lines>\r\n.\r\n`
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String readTextBlock() {
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// Consume "text:"
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while (!isAtEnd && _src[_pos] != ':') {
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_pos++;
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}
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if (!isAtEnd) _pos++; // skip ':'
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// Skip optional whitespace then newline.
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while (!isAtEnd && (_src[_pos] == ' ' || _src[_pos] == '\t')) {
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_pos++;
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}
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if (!isAtEnd && _src[_pos] == '\r') _pos++;
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if (!isAtEnd && _src[_pos] == '\n') _pos++;
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final buf = StringBuffer();
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while (!isAtEnd) {
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// Check for terminator: a lone "." on its own line.
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if (_src[_pos] == '.' &&
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(_pos + 1 >= _src.length ||
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_src[_pos + 1] == '\r' ||
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_src[_pos + 1] == '\n')) {
|
|
_pos++;
|
|
if (!isAtEnd && _src[_pos] == '\r') _pos++;
|
|
if (!isAtEnd && _src[_pos] == '\n') _pos++;
|
|
break;
|
|
}
|
|
buf.write(_src[_pos]);
|
|
_pos++;
|
|
}
|
|
return buf.toString();
|
|
}
|
|
|
|
void expectChar(String ch) {
|
|
skipWhitespaceAndComments();
|
|
if (isAtEnd || _src[_pos] != ch) {
|
|
throw SieveParseException(
|
|
'Expected "$ch" at position $_pos, got '
|
|
'"${isAtEnd ? "EOF" : _src[_pos]}"',
|
|
);
|
|
}
|
|
_pos++;
|
|
}
|
|
|
|
void expectWord(String word) {
|
|
skipWhitespaceAndComments();
|
|
final got = readWord();
|
|
if (got.toLowerCase() != word.toLowerCase()) {
|
|
throw SieveParseException(
|
|
'Expected "$word" at position $_pos, got "$got"',
|
|
);
|
|
}
|
|
}
|
|
|
|
void skipToNextSemicolon() {
|
|
while (!isAtEnd && _src[_pos] != ';') {
|
|
_pos++;
|
|
}
|
|
if (!isAtEnd) _pos++; // skip ';'
|
|
}
|
|
|
|
static bool _isWordChar(String ch) {
|
|
final c = ch.codeUnitAt(0);
|
|
return (c >= 0x41 && c <= 0x5A) || // A-Z
|
|
(c >= 0x61 && c <= 0x7A) || // a-z
|
|
(c >= 0x30 && c <= 0x39) || // 0-9
|
|
c == 0x5F || // _
|
|
c == 0x2D; // -
|
|
}
|
|
|
|
static bool _isDigit(String ch) {
|
|
final c = ch.codeUnitAt(0);
|
|
return c >= 0x30 && c <= 0x39;
|
|
}
|
|
}
|