Commit c79436f832 ensured that methods are invoked via a public
interface or public superclass when compiling Spring Expression
Language (SpEL) expressions involving method references or property
access (see MethodReference, PropertyOrFieldReference, and
collaborating support classes). However, compilation of expressions
that access properties by indexing into an object by property name is
still not properly supported in all scenarios.
To address those remaining use cases, this commit ensures that methods
are invoked via a public interface or public superclass when accessing
a property by indexing into an object by the property name – for
example, `person['name']` instead of `person.name`.
In addition, SpEL's Indexer now properly relies on the
CompilablePropertyAccessor abstraction instead of hard-coding support
for only OptimalPropertyAccessor. This greatly reduces the complexity
of the Indexer and simultaneously allows the Indexer to potentially
support other CompilablePropertyAccessor implementations.
Closes gh-29857
Although the Spring Expression Language (SpEL) generally does a good
job of locating the public declaring class or interface on which to
invoke a method in a compiled expression, prior to this commit there
were still a few unsupported use cases.
To address those remaining use cases, this commit ensures that methods
are invoked via a public interface or public superclass whenever
possible when compiling SpEL expressions.
See gh-29857
Prior to this commit, if a Spring Expression Language (SpEL) expression
referenced the root context object via the #root or #this variable, we
inserted a checkcast in the generated byte code that cast the object to
its concrete type. However if the root context object's type was
non-public, that resulted in an IllegalAccessError when the compiled
byte code was executed.
VariableReference.getValueInternal() already contains a solution for
global variables which inserts a checkcast to Object in the generated
byte code instead of to the object's concrete non-public type.
This commit therefore applies the same logic to #root (or #this when
used to reference the root context object) that is already applied to
global variables.
Closes gh-32356
Prior to this commit, the reference manual only documented indexing
support for arrays, lists, and maps.
This commit improves the overall documentation for SpEL's property
navigation and indexing support and introduces additional documentation
for indexing into Strings and Objects.
Closes gh-32355
Since the Spring Expression Language does not actually support local
variables in expressions, this commit deprecates all public APIs
related to local variables in ExpressionState (namely, the two
enterScope(...) variants that accept local variable data,
setLocalVariable(), and lookupLocalVariable()).
In addition, we no longer invoke `state.enterScope("index", ...)` in
the Projection and Selection AST nodes since the $index local variable
was never accessible within expressions anyway.
See gh-23202
Closes gh-32004
Although EvaluationContext defines the API for setting and looking up
variables, the internals of the Spring Expression Language (SpEL)
actually provide explicit support for registering functions as
variables.
This is self-evident in the two registerFunction() variants in
StandardEvaluationContext; however, functions can also be registered as
variables when using the SimpleEvaluationContext.
Since custom functions are also viable in use cases involving the
SimpleEvaluationContext, this commit documents that functions may be
registered in a SimpleEvaluationContext via setVariable().
This commit also explicitly documents the "function as a variable"
behavior in the class-level Javadoc for both StandardEvaluationContext
and SimpleEvaluationContext, as well as in the reference manual.
Closes gh-32258
To improve consistency and avoid confusion regarding primitive types
and their wrapper types, this commit ensures that we always use class
literals for primitive types.
For example, instead of using the `Void.TYPE` constant, we now
consistently use `void.class`.
Sam Brannen