https://issues.apache.org/bugzilla/show_bug.cgi?id=55792
Bug ID: 55792
Summary: Collection literals not recognized within stream
lambda expression, result in syntax error
Product: Tomcat 8
Version: 8.0.0-RC5
Hardware: All
OS: All
Status: NEW
Severity: normal
Priority: P2
Component: EL
Assignee: [email protected]
Reporter: [email protected]
I have the following EL expression in a JSP. The expression evaluates and
executes correctly without error:
${users.stream()
.filter(u -> fn:contains(u.username, '1'))
.sorted((u1, u2) -> (x = u1.lastName.compareTo(u2.lastName);
x == 0 ? u1.firstName.compareTo(u2.firstName) : x))
.toList()}
I want to apply the map operation to this as well. Section 2.3.6.4 of the JUEL
3.0 specification uses the following example, where a list-literal is used as
the right-hand side of the mapping lambda expression:
products.stream().filter(p->p.unitPrice >= 10)
.map(p->[p.name, p.unitPrice])
.toList()
So I tried applying the exact same pattern to my map operation (the new map
operation is the only change to the expression):
${users.stream()
.filter(u -> fn:contains(u.username, '1'))
.sorted((u1, u2) -> (x = u1.lastName.compareTo(u2.lastName);
x == 0 ? u1.firstName.compareTo(u2.firstName) : x))
.map(u -> [u.username, u.firstName, u.lastName])
.toList()}
I also tried using a map-literal:
${users.stream()
.filter(u -> fn:contains(u.username, '1'))
.sorted((u1, u2) -> (x = u1.lastName.compareTo(u2.lastName);
x == 0 ? u1.firstName.compareTo(u2.firstName) : x))
.map(u -> {'username':u.username, 'first':u.firstName,
'last':u.lastName})
.toList()}
However, using the list-literal in my map lambda expression results in this
error, indicating that it doesn't recognize the list-literal as a list-literal:
javax.el.ELException: java.lang.NumberFormatException: For input string:
"lastName"
javax.el.BeanELResolver.invoke(BeanELResolver.java:185)
org.apache.jasper.el.JasperELResolver.invoke(JasperELResolver.java:147)
org.apache.el.parser.AstValue.getValue(AstValue.java:158)
...
And using the map-literal results in this error, indicating that it doesn't
recognize the map-literal as a map-literal (instead, it thinks the closing
brace of the map-literal is the end of the EL expression:
javax.el.ELException: Failed to parse the expression [${users.stream()
.filter(u -> fn:contains(u.username, '1'))
.sorted((u1, u2) -> (x = u1.lastName.compareTo(u2.lastName);
x == 0 ? u1.firstName.compareTo(u2.firstName) : x))
.map(u -> {'username':u.username, 'first':u.firstName,
'last':u.lastName}]
...
<root cause>
org.apache.el.parser.ParseException: Encountered "<EOF>" at line 6, column 38.
Was expecting one of:
"." ...
")" ...
etc...
Putting parentheses around the list- and map-literals does not work, but the
Section 2.3.6.4 example doesn't use parentheses. Section 1.20 also indicates
that collection literals as bodies of lambda expressions are legal:
customers.select(c->[c.name, c.orders.sum(o->o.total)])
Collection literals are described in more detail in Section 2.2.
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