Regression: contains(@attr, "value") fails in XPath under Xidel 0.9.9 but works in 0.9.8

[hari-naga]

Description
In Xidel version 0.9.9, the following XPath expression causes an error, whereas it works correctly in version 0.9.8:

cat sample.html | xidel - -s --xpath '//table[contains(@class, "history_table")]'

Error output:

Error:
err:XPTY0004: Invalid types for function contains#2.
Got: (attribute class {"history_table table "}, attribute class {"history_table"}), "history_table"
Expected: (string?, string?) as boolean
in pxp:contains(TXQTermNodeMatcher, TXQTermConstant)

in line 1 column 9
//table[contains(@class, "history_table")]
        ^^^^^^^^^^  error occurs around here

Possible backtrace:
  $000000000050A96D  RAISEERRORMESSAGE,  line 4736 of data/xquery.pas: perhaps Q{http://expath.org/ns/file}temp-dir + 607533 ? but unlikely
  $000000000050AC1E  CHECKORCONVERTTYPES,  line 4747 of data/xquery.pas: perhaps Q{http://expath.org/ns/file}temp-dir + 608222 ? but unlikely
  $000000000052F001  EVALUATE,  line 2807 of data/xquery_terms.inc: TXQTermNamedFunction + 417
  $000000000054DA7D  FILTERSEQUENCE,  line 9198 of data/xquery.pas: perhaps TXQTermTryCatch + 67933 ? but unlikely
  $000000000054F32E  FILTER,  line 9353 of data/xquery.pas: perhaps TXQTermTryCatch + 74254 ? but unlikely
  $000000000054EDA2  EXPANDSEQUENCE,  line 9554 of data/xquery.pas: perhaps TXQTermTryCatch + 72834 ? but unlikely
  $0000000000531F83  EVALUATE,  line 3267 of data/xquery_terms.inc: perhaps TXQTermBinaryOp + 3843 ? but unlikely
  $000000000051D2F3  EVALUATE,  line 7710 of data/xquery.pas: perhaps fn:concat + 47843 ? but unlikely
  $000000000051D0A5  EVALUATE,  line 7689 of data/xquery.pas: perhaps fn:concat + 47253 ? but unlikely
  $000000000045CE28  EVALUATEQUERY,  line 2236 of xidelbase.pas: perhaps ? ? but unlikely

Call xidel with --trace-stack to get an actual backtrace

Steps to Reproduce

1. Use a simple HTML file containing: <table class="history_table table">...</table>
2. Run

   cat sample.html | xidel - -s --xpath '//table[contains(@class, "history_table")]'
   

Expected Behavior
The XPath expression should return the table data as it did in version 0.9.8.
Actual Behavior
Xidel 0.9.9 throws an error indicating contains() received invalid types, suggesting a regression in how attribute values are treated.

Environment:

• OS: Ubuntu 24.04 (aarch64 and x86_64)
• Xidel Version: 0.9.9 (works in 0.9.8)
• Terminal: Bash

[Reino17]

• Xidel Version: 0.9.9

Please be more specific, because there hasn't been a final v0.9.9 release yet. In the Xidel 0.9.9 development branch the latest version is:

$ xidel --version
Xidel 0.9.9
(20230616.8842.e14a96920e01)

And with that version I can't reproduce the issue you're encountering.

[hari-naga]

• Xidel Version: 0.9.9

Please be more specific, because there hasn't been a final v0.9.9 release yet. In the Xidel 0.9.9 development branch the latest version is:

$ xidel --version
Xidel 0.9.9
(20230616.8842.e14a96920e01)

And with that version I can't reproduce the issue you're encountering.

Thanks for the response.

hari-naga:~$ xidel --version
Xidel 0.9.9
(20230617.8842.e14a96920e01)
Compiled with FPC3.2.3 x86_64-Linux R+C+

The error occurs because the input HTML contains multiple @Class attributes on a single element (which is technically invalid HTML, but still happens in real-world data). In xidel 0.9.9, this causes the XPath expression contains(@class, "history_table") to fail because @class evaluates to a sequence of attribute nodes, not a single value.

In contrast, xidel 0.9.8 handled this case gracefully — possibly by automatically converting the attribute sequence to a string or picking the first one — so the XPath still worked.

sample HTML:

...
<table class="history_table table" class="history_table">
  ...
</table>
...

[Reino17]

I think the crucial parts are these:

xidel/xidelbase.pas

Lines 1603 to 1622 in 3e7e88a

	function extractKindFromString(v: string): TExtractionKind;
	begin
	case v of
	'auto': result := ekAuto;
	'default': result := ekDefault;
	'xpath2': result :=ekXPath2;
	'xquery1': result :=ekXQuery1;
	'xpath', 'xpath3', 'xpath3.1': result :=ekXPath3_1;
	'xquery', 'xquery3', 'xquery3.1': result :=ekXQuery3_1;
	'xpath3.0': result :=ekXPath3_0;
	'xquery3.0': result :=ekXQuery3_0;
	'xpath4.0': result := ekXPath4_0;
	'xquery4.0': result :=ekXQuery4_0;
	'css': result :=ekCSS;
	'template', 'pattern', 'html-pattern': result :=ekPatternHTML;
	'xml-pattern': result := ekPatternXML;
	'multipage': result :=ekMultipage;
	else raise EXidelException.Create('Unknown kind for the extract expression: '+v);
	end;
	end;

xidel/xidelbase.pas

Lines 733 to 754 in 3e7e88a

	procedure TXQueryCompatibilityOptions.configureParsers(kind: TExtractionKind);
	var mycopy: TXQueryCompatibilityOptions;
	begin
	mycopy := self;
	mycopy.setUnknownToDefault(kind);
	mycopy.configureParsers();
	case kind of
	ekAuto: ;
	ekPatternHTML, ekPatternXML: begin
	if kind = ekPatternHTML then htmlparser.TemplateParser.parsingModel := pmHTML
	else htmlparser.TemplateParser.parsingModel := pmStrict;
	htmlparser.QueryEngine.ParsingOptions.StringEntities:=xqseIgnoreLikeXPath;
	end;
	ekDefault: begin
	xpathparser.ParsingOptions.StringEntities:=xqseResolveLikeXQueryButIgnoreInvalid
	end;
	ekXPath2, ekXPath3_0, ekXPath3_1, ekXPath4_0, ekCSS, ekXQuery1, ekXQuery3_0, ekXQuery3_1, ekXQuery4_0: begin
	xpathparser.ParsingOptions.StringEntities:=xqseDefault;
	end;
	ekMultipage: ;
	end;
	end;

xqseIgnoreLikeXPath vs. xqseDefault.

$ xidel -s '<table class="history_table table" class="history_table">...</table>' \
        -e '//table[contains(@class, "history_table")]'
$ xidel -s '<table class="history_table table" class="history_table">...</table>' \
        --extract-kind='auto' --extract='//table[contains(@class, "history_table")]'
...

$ xidel -s '<table class="history_table table" class="history_table">...</table>' \
        --xpath='//table[contains(@class, "history_table")]'
$ xidel -s '<table class="history_table table" class="history_table">...</table>' \
        --extract-kind='xpath3' --extract='//table[contains(@class, "history_table")]'
Error:
err:XPTY0004: Invalid types for function contains#2.
Got: (attribute class {"history_table table"}, attribute class {"history_table"}), "history_table"
Expected: (string?, string?) as boolean
in pxp:contains(TXQTermNodeMatcher, TXQTermConstant)

in line 1 column 9
//table[contains(@class, "history_table")]
        ^^^^^^^^^^  error occurs around here

Possible backtrace:
  $00000000004E1B7A: perhaps Q{http://expath.org/ns/file}temp-dir + 567050 ? but unlikely
  $00000000005100CB: perhaps TXQTermBinaryOp + 5019 ? but unlikely

Call xidel with --trace-stack to get an actual backtrace

Simply don't use --xpath, as it will force Xidel to adhere to much stricter rules. Benito will have to tell you which ones exactly. Personally I only use -e, always.

[hari-naga]

Thanks for the detailed explanation — that clears it up!

You're right: avoiding --xpath and using -e or --extract with --extract-kind=auto works without errors in this case. I tested it with the exact input and the XPath now behaves as expected.

Appreciate the insight on xqseIgnoreLikeXPath vs. xqseDefault, and the explanation about stricter rules enforced by --xpath. That distinction wasn’t obvious at first, but now it makes sense.

No further questions from my side at the moment.