[JEXL-411] Allow optional leading zeroes in floating point literals - #409
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JEXL could not parse a floating point literal with an omitted leading zero (e.g. ".1"), so "(1+0.1)*2" evaluated to 2.2 while "(1+.1)*2" raised a parsing error, although ".1" is valid in Java. A leading-dot number is tokenized as "DOT DOT_IDENTIFIER", which is identical to the postfix index access "x.3". The literal is therefore recognized in the parser, in operand position, rather than at the lexer level. FloatLiteral() now also accepts ".<digits>" (only all-digit DOT_IDENTIFIER images, checked via isAllDigits) and rebuilds the value as "." + image before handing it to NumberParser. Dot-based index/property access is left untouched. Add an arithmetic test covering the JEXL-411 reproduction, leading-dot literals, unary sign and the index-access regression.
garydgregory
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henrib
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August 12, 2026 12:27
henrib
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Good thinking, nicely addressed.
| * @param image the token image | ||
| * @return true if every character is a decimal digit | ||
| */ | ||
| private static boolean isAllDigits(final String image) { |
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The method might move to JexlParser since all helpers live there.
| t=<FLOAT_LITERAL> | ||
| { jjtThis.setReal(t.image); } | ||
| | | ||
| <DOT> t=<DOT_IDENTIFIER> |
| array.add("zero"); | ||
| array.add("one"); | ||
| jc.set("array", array); | ||
| assertEquals("one", jexl.createExpression("array.1").evaluate(jc)); |
| assertEquals(0.4d, jexl.createExpression("-.5 - -.9").evaluate(jc)); | ||
| assertEquals(-1.4d, jexl.createExpression("-.5+-.9").evaluate(jc)); | ||
| // unary handling | ||
| assertEquals(-0.1d, jexl.createExpression("-.1").evaluate(jc)); |
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Add the "+.1" test for completeness.
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I pushed an additional commit to git remote add upstream https://github.com/apache/commons-jexl.git
git fetch upstream JEXL-411-leading-zeroes
git cherry-pick a4b5751a
git push origin JEXL-411-leading-zeroes |
- update changes.xml;
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Summary / Why
Fixing bug JEXL-411 (https://issues.apache.org/jira/browse/JEXL-411):
JEXL could not parse a floating point literal with an omitted leading
zero (e.g. ".1"), so "(1+0.1)*2" evaluated to 2.2 while "(1+.1)*2"
raised a parsing error, although ".1" is valid in Java.
How
A leading-dot number is tokenized as "DOT DOT_IDENTIFIER", which is
identical to the postfix index access "x.3" and cannot be told apart at
the lexer level. The literal is therefore recognized in the parser, in
operand position.
FloatLiteral()inParser.jjtnow also accepts"." (only all-digit
DOT_IDENTIFIERimages, checked via a newisAllDigitsguard) and rebuilds the value as "." + image beforehanding it to
NumberParser. Dot-based index/property access isparsed first by
MemberAccess/IdentifierAccessand left untouched.Tests
ArithmeticTest#testLeadingDotFloatLiteral:Verification
mvn(incl. apache-rat license check): BUILD SUCCESSmvn test: 1164 tests, 0 failures, 0 errorsNotes
ticket; the issue is referenced via the key in the branch, commits and
this description.
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