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api-macro: begin and explain the parameter mapping strategy

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Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
This commit is contained in:
Wolfgang Bumiller 2019-11-27 12:29:50 +01:00
parent 79f77253be
commit d02a8f4e42
2 changed files with 105 additions and 20 deletions
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119
proxmox-api-macro/src/api.rs
View File

@ -115,6 +115,17 @@ impl Schema {
Ok(())
}
fn as_object(&self) -> Option<&SchemaObject> {
match &self.item {
SchemaItem::Object(obj) => Some(obj),
_ => None,
}
}
fn find_object_property(&self, key: &str) -> Option<(bool, &Schema)> {
self.as_object().and_then(|obj| obj.find_property(key))
}
}
enum SchemaItem {
@ -223,6 +234,16 @@ impl SchemaObject {
}
Ok(())
}
fn find_property(&self, key: &str) -> Option<(bool, &Schema)> {
match self
.properties
.binary_search_by(|prope| prope.0.as_str().cmp(key))
{
Ok(idx) => Some((self.properties[idx].1, &self.properties[idx].2)),
Err(_) => None,
}
}
}
struct SchemaArray {
@ -405,8 +426,15 @@ fn derive_descriptions(
Ok(())
}
enum ParameterType<'a> {
Value,
ApiMethod,
RpcEnv,
Other(&'a syn::Type, bool, &'a Schema),
}
fn handle_function_signature(
_input_schema: &mut Schema,
input_schema: &mut Schema,
_returns_schema: &mut Schema,
func: &mut syn::ItemFn,
wrapper_ts: &mut TokenStream,
@ -417,37 +445,80 @@ fn handle_function_signature(
bail!(sig => "async fn is currently not supported");
}
let mut has_api_method = false;
let mut has_rpc_env = false;
let mut api_method_param = None;
let mut rpc_env_param = None;
let mut inputs = HashMap::<SimpleIdent, &syn::Type>::new();
let mut inputs = HashMap::<SimpleIdent, ParameterType>::new();
let mut need_wrapper = false;
// Go through the function signature to figure out whether we need to create an internal
// wrapping function.
//
// First: go through the parameters:
for input in sig.inputs.iter() {
// `self` types are not supported:
let pat_type = match input {
syn::FnArg::Receiver(r) => bail!(r => "methods taking a 'self' are not supported"),
syn::FnArg::Typed(pat_type) => pat_type,
};
// Normally function parameters are simple Ident patterns. Anything else is an error.
let pat = match &*pat_type.pat {
syn::Pat::Ident(pat) => pat,
_ => bail!(pat_type => "unsupported parameter type"),
};
if is_api_method_type(&pat_type.ty) {
if has_api_method {
// Here's the deal: we need to distinguish between parameters we need to extract before
// calling the function, a general "Value" parameter covering all the remaining json
// values, and our 2 fixed function parameters: `&ApiMethod` and `&mut dyn RpcEnvironment`.
//
// Our strategy is as follows:
// 1) See if the parameter name also appears in the input schema. In this case we
// assume that we want the parameter to be extracted from the `Value` and passed
// directly to the function.
//
// 2) Check the parameter type for `&ApiMethod` and remember its position (since we may
// need to reorder it!)
//
// 3) Check the parameter type for `&dyn RpcEnvironment` and remember its position
// (since we may need to reorder it!).
//
// 4) Check for a `Value` or `serde_json::Value` parameter. This becomes the
// "catch-all" parameter and only 1 may exist.
// Note that we may still use further `Value` parameters if they have been
// explicitly named in the `input_schema`. However, only 1 unnamed `Value` parameter
// is allowed.
// If no such parameter exists, we automatically fail the function if the `Value` is
// not empty after extracting the parameters.
//
// 5) Finally, if none of the above conditions are met, we do not know what to do and
// bail out with an error.
let param_type = if let Some((optional, schema)) =
input_schema.find_object_property(&pat.ident.to_string())
{
need_wrapper = true;
// Found an explicit parameter: extract it:
ParameterType::Other(&pat_type.ty, optional, schema)
} else if is_api_method_type(&pat_type.ty) {
if api_method_param.is_some() {
bail!(pat_type => "multiple ApiMethod parameters found");
}
has_api_method = true;
}
if is_rpc_env_type(&pat_type.ty) {
if has_rpc_env {
api_method_param = Some(inputs.len());
ParameterType::ApiMethod
} else if is_rpc_env_type(&pat_type.ty) {
if rpc_env_param.is_some() {
bail!(pat_type => "multiple RpcEnvironment parameters found");
}
has_rpc_env = true;
}
rpc_env_param = Some(inputs.len());
ParameterType::RpcEnv
} else if is_value_type(&pat_type.ty) {
ParameterType::Value
} else {
bail!(&pat.ident => "unexpected parameter");
};
if inputs
.insert(pat.ident.clone().into(), &pat_type.ty)
.insert(pat.ident.clone().into(), param_type)
.is_some()
{
bail!(&pat.ident => "duplicate parameter");
@ -456,7 +527,7 @@ fn handle_function_signature(
let func_name = &sig.ident;
if inputs.len() == 3 && has_api_method && has_rpc_env {
if (inputs.len(), api_method_param, rpc_env_param) == (3, Some(1), Some(2)) {
// No wrapper needed:
return Ok(func_name.clone());
}
@ -466,6 +537,8 @@ fn handle_function_signature(
func.sig.ident.span(),
);
let mut args = TokenStream::new();
// build the wrapping function:
wrapper_ts.extend(quote! {
fn #api_func_name(
@ -503,3 +576,19 @@ fn is_rpc_env_type(ty: &syn::Type) -> bool {
}
false
}
/// Note that we cannot handle renamed imports at all here...
fn is_value_type(ty: &syn::Type) -> bool {
if let syn::Type::Path(p) = ty {
let segs = &p.path.segments;
match segs.len() {
1 => return segs.last().unwrap().ident == "Value",
2 => {
return segs.first().unwrap().ident == "serde_json"
&& segs.last().unwrap().ident == "Value"
}
_ => return false,
}
}
false
}

6
proxmox-api-macro/tests/api1.rs
View File

@ -41,10 +41,6 @@ use serde_json::Value;
/// Create or verify authentication ticket.
///
/// Returns: A ticket.
fn create_ticket(
_param: Value,
_info: &ApiMethod,
_rpcenv: &mut dyn RpcEnvironment,
) -> Result<Value, Error> {
fn create_ticket(_param: Value) -> Result<Value, Error> {
panic!("implement me");
}