Backslashes aren't properly handled: they seem to be escaped twice

[MV-GH]

1. Description

Backslashes aren't properly handled, It seems to escape them twice: \\\\ => \\ =>\

2. Exception

If you are seeing an exception, include the full exception details (message and stack trace).

Exception message:"parsing \"te\\st\" - Unrecognized escape sequence \\s."
Stack trace:
"   at System.Linq.Dynamic.Core.Parser.StringParser.ParseString(String s)\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseStringLiteral()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParsePrimaryStart()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParsePrimary()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseUnary()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseMultiplicative()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseAdditive()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseShiftOperator()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseComparisonOperator()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseLogicalAndOrOperator()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseIn()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseAndOperator()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseOrOperator()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseLambdaOperator()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseNullCoalescingOperator()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseConditionalOperator()\r\n   at System.Linq.Dynamic.Core.Parser.ExpressionParser.Parse(Type resultType, Boolean createParameterCtor)\r\n   at System.Linq.Dynamic.Core.DynamicExpressionParser.ParseLambda(Type delegateType, ParsingConfig parsingConfig, Boolean createParameterCtor, ParameterExpression[] parameters, Type resultType, String expression, Object[] values)\r\n   at System.Linq.Dynamic.Core.DynamicExpressionParser.ParseLambda(ParsingConfig parsingConfig, Boolean createParameterCtor, Type itType, Type resultType, String expression, Object[] values)\r\n   at System.Linq.Dynamic.Core.DynamicQueryableExtensions.Where(IQueryable source, ParsingConfig config, String predicate, Object[] args)\r\n   at System.Linq.Dynamic.Core.DynamicQueryableExtensions.Where[TSource](IQueryable`1 source, ParsingConfig config, String predicate, Object[] args)\r\n   at System.Linq.Dynamic.Core.DynamicQueryableExtensions.Where[TSource](IQueryable`1 source, String predicate, Object[] args)\r\n   at dynamicLinqTest.Program.Main(String[] args) in C:\\Users\\mave\\source\\repos\\dynamicLinqTest\\dynamicLinqTest\\Program.cs:line 17"

3. Fiddle or Project

FIDDLE:
https://dotnetfiddle.net/CVPBh3

REPRO

 var t1 = new List<string>() { "test" }.AsQueryable().Where("it == \"test\"").ToList(); // works
 var t2 = new List<string>(){ "t\\est" }.AsQueryable().Where("it == \"t\\est\"").ToList(); // Doesn't error but doesn't work
 var t3 = new List<string>() { "t\\est" }.AsQueryable().Where("it == \"t\\\\est\"").ToList(); // Works but it shouldn't
 var t4 = new List<string>() { "te\\st" }.AsQueryable().Where("it == \"te\\st\"").ToList(); // Throws an error, System.Linq.Dynamic.Core.Exceptions.ParseException: 'parsing "te\st" - Unrecognized escape sequence \s.'
 var t5 = new List<string>() { "test\\" }.AsQueryable().Where("it == \"test\\\"").ToList(); // Throws an error, System.Linq.Dynamic.Core.Exceptions.ParseException: 'Unterminated string literal'

[StefH]

@MV-GH
Because the backslash is used within an already escaped string : "it == \"XXX\", you need to double escape the backslash.
So t1 and t3 are valid scenarios.

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Note that this behavior was not entirely correct in previous versions been fixed in version v1.2.13 ; issue #545.

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See also
https://github.com/zzzprojects/System.Linq.Dynamic.Core/blob/e71b3560820d466237247334ffa4220af41b797c/test/System.Linq.Dynamic.Core.Tests/Parser/StringParserTests.cs

[MV-GH]

Thanks for the quick response! Could this behavior be added to the documentation?

[StefH]

Docs are updated.