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use crate::{
errors::*,
objects::{AutoLocal, JMethodID, JObject},
signature::{JavaType, Primitive},
JNIEnv,
};
/// Wrapper for JObjects that implement `java/util/Map`. Provides methods to get
/// and set entries and a way to iterate over key/value pairs.
///
/// Looks up the class and method ids on creation rather than for every method
/// call.
pub struct JMap<'a: 'b, 'b> {
internal: JObject<'a>,
class: AutoLocal<'a, 'b>,
get: JMethodID<'a>,
put: JMethodID<'a>,
remove: JMethodID<'a>,
env: &'b JNIEnv<'a>,
}
impl<'a: 'b, 'b> ::std::ops::Deref for JMap<'a, 'b> {
type Target = JObject<'a>;
fn deref(&self) -> &Self::Target {
&self.internal
}
}
impl<'a: 'b, 'b> From<JMap<'a, 'b>> for JObject<'a> {
fn from(other: JMap<'a, 'b>) -> JObject<'a> {
other.internal
}
}
impl<'a: 'b, 'b> JMap<'a, 'b> {
/// Create a map from the environment and an object. This looks up the
/// necessary class and method ids to call all of the methods on it so that
/// exra work doesn't need to be done on every method call.
pub fn from_env(env: &'b JNIEnv<'a>, obj: JObject<'a>) -> Result<JMap<'a, 'b>> {
let class = env.auto_local(env.find_class("java/util/Map")?);
let get = env.get_method_id(&class, "get", "(Ljava/lang/Object;)Ljava/lang/Object;")?;
let put = env.get_method_id(
&class,
"put",
"(Ljava/lang/Object;Ljava/lang/Object;\
)Ljava/lang/Object;",
)?;
let remove =
env.get_method_id(&class, "remove", "(Ljava/lang/Object;)Ljava/lang/Object;")?;
Ok(JMap {
internal: obj,
class,
get,
put,
remove,
env,
})
}
/// Look up the value for a key. Returns `Some` if it's found and `None` if
/// a null pointer would be returned.
pub fn get(&self, key: JObject<'a>) -> Result<Option<JObject<'a>>> {
let result = self.env.call_method_unchecked(
self.internal,
self.get,
JavaType::Object("java/lang/Object".into()),
&[key.into()],
);
match result {
Ok(val) => Ok(Some(val.l()?)),
Err(e) => match *e.kind() {
ErrorKind::NullPtr(_) => Ok(None),
_ => Err(e),
},
}
}
/// Look up the value for a key. Returns `Some` with the old value if the
/// key already existed and `None` if it's a new key.
pub fn put(&self, key: JObject<'a>, value: JObject<'a>) -> Result<Option<JObject<'a>>> {
let result = self.env.call_method_unchecked(
self.internal,
self.put,
JavaType::Object("java/lang/Object".into()),
&[key.into(), value.into()],
);
match result {
Ok(val) => Ok(Some(val.l()?)),
Err(e) => match *e.kind() {
ErrorKind::NullPtr(_) => Ok(None),
_ => Err(e),
},
}
}
/// Remove a value from the map. Returns `Some` with the removed value and
/// `None` if there was no value for the key.
pub fn remove(&self, key: JObject<'a>) -> Result<Option<JObject<'a>>> {
let result = self.env.call_method_unchecked(
self.internal,
self.remove,
JavaType::Object("java/lang/Object".into()),
&[key.into()],
);
match result {
Ok(val) => Ok(Some(val.l()?)),
Err(e) => match *e.kind() {
ErrorKind::NullPtr(_) => Ok(None),
_ => Err(e),
},
}
}
/// Get key/value iterator for the map. This is done by getting the
/// `EntrySet` from java and iterating over it.
pub fn iter(&self) -> Result<JMapIter<'a, 'b, '_>> {
let iter_class = self
.env
.auto_local(self.env.find_class("java/util/Iterator")?);
let has_next = self.env.get_method_id(&iter_class, "hasNext", "()Z")?;
let next = self
.env
.get_method_id(&iter_class, "next", "()Ljava/lang/Object;")?;
let entry_class = self
.env
.auto_local(self.env.find_class("java/util/Map$Entry")?);
let get_key = self
.env
.get_method_id(&entry_class, "getKey", "()Ljava/lang/Object;")?;
let get_value = self
.env
.get_method_id(&entry_class, "getValue", "()Ljava/lang/Object;")?;
// Get the iterator over Map entries.
// Use the local frame till #109 is resolved, so that implicitly looked-up
// classes are freed promptly.
let iter = self.env.with_local_frame(16, || {
let entry_set = self
.env
.call_method_unchecked(
self.internal,
(&self.class, "entrySet", "()Ljava/util/Set;"),
JavaType::Object("java/util/Set".into()),
&[],
)?
.l()?;
let iter = self
.env
.call_method_unchecked(
entry_set,
("java/util/Set", "iterator", "()Ljava/util/Iterator;"),
JavaType::Object("java/util/Iterator".into()),
&[],
)?
.l()?;
Ok(iter)
})?;
let iter = self.env.auto_local(iter);
Ok(JMapIter {
map: &self,
has_next,
next,
get_key,
get_value,
iter,
})
}
}
/// An iterator over the keys and values in a map.
///
/// TODO: make the iterator implementation for java iterators its own thing
/// and generic enough to use elsewhere.
pub struct JMapIter<'a, 'b, 'c> {
map: &'c JMap<'a, 'b>,
has_next: JMethodID<'a>,
next: JMethodID<'a>,
get_key: JMethodID<'a>,
get_value: JMethodID<'a>,
iter: AutoLocal<'a, 'b>,
}
impl<'a: 'b, 'b: 'c, 'c> JMapIter<'a, 'b, 'c> {
fn get_next(&self) -> Result<Option<(JObject<'a>, JObject<'a>)>> {
let iter = self.iter.as_obj();
let has_next = self
.map
.env
.call_method_unchecked(
iter,
self.has_next,
JavaType::Primitive(Primitive::Boolean),
&[],
)?
.z()?;
if !has_next {
return Ok(None);
}
let next = self
.map
.env
.call_method_unchecked(
iter,
self.next,
JavaType::Object("java/util/Map$Entry".into()),
&[],
)?
.l()?;
let key = self
.map
.env
.call_method_unchecked(
next,
self.get_key,
JavaType::Object("java/lang/Object".into()),
&[],
)?
.l()?;
let value = self
.map
.env
.call_method_unchecked(
next,
self.get_value,
JavaType::Object("java/lang/Object".into()),
&[],
)?
.l()?;
Ok(Some((key, value)))
}
}
impl<'a: 'b, 'b: 'c, 'c> Iterator for JMapIter<'a, 'b, 'c> {
type Item = (JObject<'a>, JObject<'a>);
fn next(&mut self) -> Option<Self::Item> {
match self.get_next() {
Ok(Some(n)) => Some(n),
_ => None,
}
}
}