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Posted to issues@commons.apache.org by "NikRom5531 (via GitHub)" <gi...@apache.org> on 2026/08/12 10:42:36 UTC
[PR] JEXL-411: Allow optional leading zeroes in floating point literals [commons-jexl]
NikRom5531 opened a new pull request, #409:
URL: https://github.com/apache/commons-jexl/pull/409
### 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()` in `Parser.jjt` now also accepts
".<digits>" (only all-digit `DOT_IDENTIFIER` images, checked via a new
`isAllDigits` guard) and rebuilds the value as "." + image before
handing it to `NumberParser`. Dot-based index/property access is
parsed first by `MemberAccess`/`IdentifierAccess` and left untouched.
### Tests
`ArithmeticTest#testLeadingDotFloatLiteral`:
- "(1+.1)*2" == 2.2 (JEXL-411 reproduction)
- "(1+0.1)*2" == 2.2 (regression)
- ".1" == 0.1, "-.1" == -0.1, ".5 + .5" == 1.0, ".55" == 0.55
- unary/compound: "-.1+.2" == 0.1, ".1+-.2" == -0.1, ".5 - -.9" == 1.4
- "array.1" still resolves to index access (regression)
- The test fails on the previous grammar and passes on this one.
### Verification
- `mvn` (incl. apache-rat license check): BUILD SUCCESS
- `mvn test`: 1164 tests, 0 failures, 0 errors
### Notes
- The JIRA account was read-only, so a PR link could not be added to the
ticket; the issue is referenced via the key in the branch, commits and
this description.
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Re: [PR] [JEXL-411] Allow optional leading zeroes in floating point literals [commons-jexl]
Posted by "henrib (via GitHub)" <gi...@apache.org>.
henrib commented on code in PR #409:
URL: https://github.com/apache/commons-jexl/pull/409#discussion_r3766406888
##########
src/main/java/org/apache/commons/jexl3/parser/Parser.jjt:
##########
@@ -107,6 +107,27 @@ public final class Parser extends JexlParser
jjtree.reset();
}
}
+
+ /**
+ * Checks whether a token image is composed only of decimal digits.
+ * <p>Used to recognize a floating point literal with an omitted leading
+ * zero (e.g. {@code .1}) that is tokenized as {@code DOT DOT_IDENTIFIER}.</p>
+ *
+ * @param image the token image
+ * @return true if every character is a decimal digit
+ */
+ private static boolean isAllDigits(final String image) {
Review Comment:
The method might move to JexlParser since all helpers live there.
##########
src/test/java/org/apache/commons/jexl3/ArithmeticTest.java:
##########
@@ -2341,4 +2341,32 @@ void setOptions(final JexlOptions options) {
this.options = options;
}
}
+
+ @Test void testLeadingDotFloatLiteral() {
+ final JexlEngine jexl = new JexlBuilder().create();
+ final JexlContext jc = new MapContext();
+ // the exact case from JEXL-411
+ assertEquals(2.2d, jexl.createExpression("(1+.1)*2").evaluate(jc));
+ // the regression case that already worked
+ assertEquals(2.2d, jexl.createExpression("(1+0.1)*2").evaluate(jc));
+ // standalone and compound leading-dot literals
+ assertEquals(0.1d, jexl.createExpression(".1").evaluate(jc));
+ assertEquals(1.0d, jexl.createExpression(".5 + .5").evaluate(jc));
+ assertEquals(0.55d, jexl.createExpression(".55").evaluate(jc));
+ assertEquals(0.1d, jexl.createExpression("-.1 + .2").evaluate(jc));
+ assertEquals(-0.1d, jexl.createExpression(".1 + -.2").evaluate(jc));
+ assertEquals(0.1d, jexl.createExpression("-.1+.2").evaluate(jc));
+ assertEquals(-0.1d, jexl.createExpression(".1+-.2").evaluate(jc));
+ assertEquals(1.4d, jexl.createExpression(".5 - -.9").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));
+ // property / index access via a dot must keep working (not parsed as a float)
+ final List<Object> array = new java.util.ArrayList<>();
+ array.add("zero");
+ array.add("one");
+ jc.set("array", array);
+ assertEquals("one", jexl.createExpression("array.1").evaluate(jc));
Review Comment:
Add the 0/zero test.
##########
src/main/java/org/apache/commons/jexl3/parser/Parser.jjt:
##########
@@ -1064,6 +1085,9 @@ void FloatLiteral() #NumberLiteral:
{
t=<FLOAT_LITERAL>
{ jjtThis.setReal(t.image); }
+ |
+ <DOT> t=<DOT_IDENTIFIER>
Review Comment:
Nice trick :-)
##########
src/test/java/org/apache/commons/jexl3/ArithmeticTest.java:
##########
@@ -2341,4 +2341,32 @@ void setOptions(final JexlOptions options) {
this.options = options;
}
}
+
+ @Test void testLeadingDotFloatLiteral() {
+ final JexlEngine jexl = new JexlBuilder().create();
+ final JexlContext jc = new MapContext();
+ // the exact case from JEXL-411
+ assertEquals(2.2d, jexl.createExpression("(1+.1)*2").evaluate(jc));
+ // the regression case that already worked
+ assertEquals(2.2d, jexl.createExpression("(1+0.1)*2").evaluate(jc));
+ // standalone and compound leading-dot literals
+ assertEquals(0.1d, jexl.createExpression(".1").evaluate(jc));
+ assertEquals(1.0d, jexl.createExpression(".5 + .5").evaluate(jc));
+ assertEquals(0.55d, jexl.createExpression(".55").evaluate(jc));
+ assertEquals(0.1d, jexl.createExpression("-.1 + .2").evaluate(jc));
+ assertEquals(-0.1d, jexl.createExpression(".1 + -.2").evaluate(jc));
+ assertEquals(0.1d, jexl.createExpression("-.1+.2").evaluate(jc));
+ assertEquals(-0.1d, jexl.createExpression(".1+-.2").evaluate(jc));
+ assertEquals(1.4d, jexl.createExpression(".5 - -.9").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));
Review Comment:
Add the "+.1" test for completeness.
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Re: [PR] [JEXL-411] Allow optional leading zeroes in floating point literals [commons-jexl]
Posted by "henrib (via GitHub)" <gi...@apache.org>.
henrib merged PR #409:
URL: https://github.com/apache/commons-jexl/pull/409
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Re: [PR] [JEXL-411] Allow optional leading zeroes in floating point literals [commons-jexl]
Posted by "henrib (via GitHub)" <gi...@apache.org>.
henrib commented on PR #409:
URL: https://github.com/apache/commons-jexl/pull/409#issuecomment-5267091109
I pushed an additional commit to `apache/commons-jexl:JEXL-411-leading-zeroes` (commit `a4b5751a`: "JEXL-411: move isAllDigits to JexlParser; - update changes.xml;") but was unable to push it directly to your fork. Could you pull it into your branch?
```bash
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
```
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