struct FunctionReturnShape<'a> {
capsule: Option<(&'a crate::core::config::FfiCapsuleTypeConfig, bool)>,
opaque: bool,
optional_opaque: bool,
}
struct FunctionParamProjection {
signature: String,
unmarshal: String,
call_arg: String,
}
#[allow(clippy::too_many_arguments)]
fn emit_function_shim(
out: &mut String,
symbol: &str,
function: &crate::core::ir::FunctionDef,
opaque_type_names: &std::collections::HashSet<&str>,
capsule_types: &std::collections::HashMap<String, crate::core::config::FfiCapsuleTypeConfig>,
core_crate_prefix: &str,
) {
let shape = function_return_shape(&function.return_type, opaque_type_names, capsule_types);
let return_null = function_return_null(&function.return_type, &shape);
let (param_sigs, unmarshal, call_args) = project_function_params(&function.params, opaque_type_names, return_null);
out.push_str(&template_env::render(
"function_shim_open.rs.jinja",
crate::alef_context! {
symbol => symbol,
param_sigs => param_sigs,
ret_decl => function_return_declaration(&function.return_type, &shape),
},
));
out.push_str(&unmarshal);
let core_function = core_function_path(&function.rust_path, core_crate_prefix);
let call = if call_args.is_empty() {
format!("{core_function}()")
} else {
format!("{core_function}({call_args})")
};
emit_function_return(out, function, &shape, &call, return_null);
}
fn function_return_shape<'a>(
return_type: &TypeRef,
opaque_type_names: &std::collections::HashSet<&str>,
capsule_types: &'a std::collections::HashMap<String, crate::core::config::FfiCapsuleTypeConfig>,
) -> FunctionReturnShape<'a> {
let opaque = matches!(return_type, TypeRef::Named(name) if opaque_type_names.contains(name.as_str()));
let optional_opaque = matches!(
return_type,
TypeRef::Optional(inner)
if matches!(inner.as_ref(), TypeRef::Named(name) if opaque_type_names.contains(name.as_str()))
);
let capsule = match return_type {
TypeRef::Named(name) => capsule_types.get(name).map(|config| (config, false)),
TypeRef::Optional(inner) => match inner.as_ref() {
TypeRef::Named(name) => capsule_types.get(name).map(|config| (config, true)),
_ => None,
},
_ => None,
};
FunctionReturnShape {
capsule,
opaque,
optional_opaque,
}
}
fn function_return_declaration(return_type: &TypeRef, shape: &FunctionReturnShape<'_>) -> String {
if shape.opaque || shape.optional_opaque || shape.capsule.is_some() {
" -> jlong".to_string()
} else {
method_return_type_decl(return_type)
}
}
fn function_return_null<'a>(return_type: &'a TypeRef, shape: &FunctionReturnShape<'_>) -> &'a str {
if shape.opaque || shape.optional_opaque || shape.capsule.is_some() {
"0"
} else {
method_return_null(return_type)
}
}
fn core_function_path(rust_path: &str, core_crate_prefix: &str) -> String {
let path = rust_path.replace('-', "_");
let prefix = format!("{}::", core_crate_prefix.replace('-', "_"));
if path.starts_with(&prefix) {
path.replacen(&prefix, "core_crate::", 1)
} else if let Some((_sibling_crate, item)) = path.split_once("::") {
format!("core_crate::{item}")
} else {
format!("core_crate::{path}")
}
}
fn project_function_params(
params: &[ParamDef],
opaque_type_names: &std::collections::HashSet<&str>,
return_null: &str,
) -> (String, String, String) {
let mut signatures = String::new();
let mut unmarshal = String::new();
let mut call_args = Vec::new();
for param in params {
let projection = project_function_param(param, opaque_type_names, return_null);
signatures.push_str(&projection.signature);
unmarshal.push_str(&projection.unmarshal);
call_args.push(projection.call_arg);
}
(signatures, unmarshal, call_args.join(", "))
}
fn project_function_param(
param: &ParamDef,
opaque_type_names: &std::collections::HashSet<&str>,
return_null: &str,
) -> FunctionParamProjection {
let rust_name = param.name.replace('-', "_");
let base_type = method_param_base_type(param);
let projection = match base_type {
TypeRef::String => project_string_function_param(param, &rust_name, return_null),
TypeRef::Primitive(primitive) => project_primitive_function_param(param, primitive, &rust_name, return_null),
TypeRef::Vec(inner) if matches!(inner.as_ref(), TypeRef::Primitive(PrimitiveType::U8)) => {
project_bytes_function_param(param, &rust_name, return_null)
}
TypeRef::Bytes => project_bytes_function_param(param, &rust_name, return_null),
TypeRef::Path => project_path_function_param(param, &rust_name, return_null),
TypeRef::Named(type_name) if opaque_type_names.contains(type_name.as_str()) => {
project_opaque_function_param(type_name, &rust_name, return_null)
}
_ => project_complex_function_param(param, base_type, &rust_name, return_null),
};
project_function_newtype_param(param, base_type, &rust_name, projection)
}
fn project_function_newtype_param(
param: &ParamDef,
base_type: &TypeRef,
rust_name: &str,
mut projection: FunctionParamProjection,
) -> FunctionParamProjection {
if param.newtype_wrapper.is_none() {
return projection;
}
let source = if param.optional && matches!(base_type, TypeRef::String) {
format!("if {rust_name}.is_empty() {{ None }} else {{ Some({rust_name}) }}")
} else {
rust_name.to_string()
};
let converted = jni_param_newtype_to_core(&source, param).expect("newtype wrapper is present");
if !param.is_ref {
projection.call_arg = converted;
return projection;
}
let binding = format!("{rust_name}_newtype");
projection
.unmarshal
.push_str(&format!(" let {binding} = {converted};\n"));
projection.call_arg = if param.optional {
format!("{binding}.as_ref()")
} else {
format!("&{binding}")
};
projection
}
fn project_string_function_param(param: &ParamDef, rust_name: &str, return_null: &str) -> FunctionParamProjection {
let call_arg = if param.optional {
let payload = if param.is_ref {
format!("&{rust_name}")
} else {
rust_name.to_string()
};
format!("if {rust_name}.is_empty() {{ None }} else {{ Some({payload}) }}")
} else if param.is_ref {
format!("&{rust_name}")
} else {
rust_name.to_string()
};
FunctionParamProjection {
signature: render_param_decl(rust_name, "JString"),
unmarshal: render_string_unmarshal(rust_name, return_null),
call_arg,
}
}
fn project_primitive_function_param(
param: &ParamDef,
primitive: &PrimitiveType,
rust_name: &str,
return_null: &str,
) -> FunctionParamProjection {
if matches!(primitive, PrimitiveType::U32) {
let binding = format!("{rust_name}_checked");
let unmarshal = if param.optional {
format!(
" let {binding} = if {rust_name} == -1 {{ None }} else {{\n match u32::try_from({rust_name}) {{\n Ok(value) => Some(value),\n Err(_) => {{ throw_jni_error(env, \"parameter '{rust_name}' must be between 0 and u32::MAX\"); return {return_null}; }}\n }}\n }};\n"
)
} else {
format!(
" let {binding} = match u32::try_from({rust_name}) {{\n Ok(value) => value,\n Err(_) => {{ throw_jni_error(env, \"parameter '{rust_name}' must be between 0 and u32::MAX\"); return {return_null}; }}\n }};\n"
)
};
return FunctionParamProjection {
signature: render_param_decl(rust_name, jni_primitive_type(primitive)),
unmarshal,
call_arg: binding,
};
}
let cast = primitive_cast(primitive);
let cast_expression = if cast.is_empty() {
rust_name.to_string()
} else {
format!("{rust_name} as {cast}")
};
let call_arg = if param.optional {
primitive_zero_literal(primitive).map_or_else(
|| format!("Some({cast_expression})"),
|zero| format!("if {rust_name} != {zero} {{ Some({cast_expression}) }} else {{ None }}"),
)
} else {
cast_expression
};
FunctionParamProjection {
signature: render_param_decl(rust_name, jni_primitive_type(primitive)),
unmarshal: String::new(),
call_arg,
}
}
fn project_bytes_function_param(param: &ParamDef, rust_name: &str, return_null: &str) -> FunctionParamProjection {
FunctionParamProjection {
signature: render_param_decl(rust_name, "JString"),
unmarshal: render_base64_bytes_unmarshal(rust_name, return_null, param.optional),
call_arg: bytes_call_arg(rust_name, param.optional, param.is_ref),
}
}
fn project_path_function_param(param: &ParamDef, rust_name: &str, return_null: &str) -> FunctionParamProjection {
let mut unmarshal = render_string_unmarshal(rust_name, return_null);
unmarshal.push_str(&format!(
" let {rust_name} = std::path::PathBuf::from({rust_name});\n"
));
let call_arg = if param.optional {
format!("if {rust_name}.as_os_str().is_empty() {{ None }} else {{ Some({rust_name}) }}")
} else if param.is_ref {
format!("&{rust_name}")
} else {
rust_name.to_string()
};
FunctionParamProjection {
signature: render_param_decl(rust_name, "JString"),
unmarshal,
call_arg,
}
}
fn project_opaque_function_param(type_name: &str, rust_name: &str, return_null: &str) -> FunctionParamProjection {
FunctionParamProjection {
signature: render_param_decl(rust_name, "jlong"),
unmarshal: template_env::render(
"opaque_handle_unmarshal.rs.jinja",
crate::alef_context! {
name => rust_name,
type_path => format!("core_crate::{type_name}"),
ret_null => return_null,
},
),
call_arg: rust_name.to_string(),
}
}
fn project_complex_function_param(
param: &ParamDef,
base_type: &TypeRef,
rust_name: &str,
return_null: &str,
) -> FunctionParamProjection {
let type_path = type_ref_to_core_path_with_btree(base_type, "core_crate", param.map_is_btree);
let mut unmarshal = render_complex_unmarshal(rust_name, &type_path, return_null, param.optional);
if param.is_ref && param.is_mut && !param.optional {
unmarshal.push_str(&format!(" let mut {rust_name} = {rust_name};\n"));
}
let call_arg = if param.optional {
rust_name.to_string()
} else if needs_vec_string_refs(param, base_type) {
unmarshal.push_str(&render_vec_string_refs_binding(rust_name));
vec_string_refs_arg(rust_name)
} else if param.is_ref && param.is_mut {
format!("&mut {rust_name}")
} else if param.is_ref {
format!("&{rust_name}")
} else {
rust_name.to_string()
};
FunctionParamProjection {
signature: render_param_decl(rust_name, "JString"),
unmarshal,
call_arg,
}
}
fn emit_function_return(
out: &mut String,
function: &crate::core::ir::FunctionDef,
shape: &FunctionReturnShape<'_>,
call: &str,
return_null: &str,
) {
let has_error = function.error_type.is_some();
let indent = if has_error { " " } else { " " };
let body = render_function_return_body(function, shape, indent, return_null);
let (ok_body, value_body) = if has_error {
(body.as_str(), "")
} else {
("", body.as_str())
};
render_call_result_body(
out,
call,
&CallResultShape {
is_async: function.is_async,
has_error,
ret_null: return_null,
ok_body,
value_body,
},
);
}
fn render_function_return_body(
function: &crate::core::ir::FunctionDef,
shape: &FunctionReturnShape<'_>,
indent: &str,
return_null: &str,
) -> String {
if let Some((capsule, optional)) = shape.capsule {
return render_method_capsule_return(capsule, optional, function.returns_ref, function.returns_cow, indent);
}
if shape.opaque {
let value = capsule_owned_value("v", function.returns_ref, function.returns_cow);
return format!("{indent}Box::into_raw(Box::new({value})) as jlong\n");
}
if shape.optional_opaque {
let value = capsule_owned_value("inner", function.returns_ref, function.returns_cow);
return format!(
"{indent}match v {{\n{indent} None => 0i64,\n{indent} Some(inner) => \
Box::into_raw(Box::new({value})) as jlong,\n{indent}}}\n"
);
}
let mut body = String::new();
if let Some(wrapper) = &function.return_newtype_wrapper {
let converted = jni_return_newtype_from_core("v", wrapper);
body.push_str(&format!("{indent}let v = {converted};\n"));
}
emit_return_marshal_with_indent(&mut body, &function.return_type, indent, return_null);
body
}
#[cfg(test)]
mod function_shims_tests {
use super::*;
use crate::core::ir::ParamDef;
fn primitive_param(name: &str, primitive: PrimitiveType) -> ParamDef {
ParamDef {
name: name.to_string(),
ty: TypeRef::Primitive(primitive),
..Default::default()
}
}
#[test]
fn f64_param_call_arg_has_no_cast() {
let param = primitive_param("cost_usd", PrimitiveType::F64);
let projection = project_primitive_function_param(¶m, &PrimitiveType::F64, "cost_usd", "0");
assert_eq!(projection.call_arg, "cost_usd");
}
#[test]
fn u64_param_call_arg_still_casts() {
let param = primitive_param("count", PrimitiveType::U64);
let projection = project_primitive_function_param(¶m, &PrimitiveType::U64, "count", "0");
assert_eq!(projection.call_arg, "count as u64");
}
#[test]
fn optional_u32_distinguishes_none_from_zero_and_rejects_other_negatives() {
let mut param = primitive_param("max", PrimitiveType::U32);
param.optional = true;
let projection = project_primitive_function_param(¶m, &PrimitiveType::U32, "max", "0");
assert!(
projection.unmarshal.contains("max == -1 { None }"),
"{}",
projection.unmarshal
);
assert!(
projection.unmarshal.contains("Ok(value) => Some(value)"),
"{}",
projection.unmarshal
);
assert!(
projection.unmarshal.contains("u32::try_from(max)"),
"{}",
projection.unmarshal
);
assert!(
!projection.unmarshal.contains("max <= 0"),
"Some(0) must survive: {}",
projection.unmarshal
);
}
}