1  // Copyright (c) 2019-2025 Alpha-Delta Network Inc.
 2  // This file is part of the deltavm library.
 3  
 4  // Licensed under the Apache License, Version 2.0 (the "License");
 5  // you may not use this file except in compliance with the License.
 6  // You may obtain a copy of the License at:
 7  
 8  // http://www.apache.org/licenses/LICENSE-2.0
 9  
10  // Unless required by applicable law or agreed to in writing, software
11  // distributed under the License is distributed on an "AS IS" BASIS,
12  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  // See the License for the specific language governing permissions and
14  // limitations under the License.
15  
16  use super::*;
17  
18  impl<A: Alpha> Future<A> {
19      /// Returns the value from the given path.
20      pub fn find<A0: Into<Access<A>> + Clone + Debug>(&self, path: &[A0]) -> Result<Value<A>> {
21          // Ensure the path is not empty.
22          ensure!(!path.is_empty(), "Attempted to find an argument with an empty path.");
23  
24          // A helper enum to track the the argument.
25          enum ArgumentRefType<'a, A: Alpha> {
26              /// A plaintext type.
27              Plaintext(&'a Plaintext<A>),
28              /// A future.
29              Future(&'a Future<A>),
30          }
31  
32          // Initialize a value starting from the top-level.
33          let mut value = ArgumentRefType::Future(self);
34  
35          // Iterate through the path to retrieve the value.
36          for access in path.iter() {
37              let access = access.clone().into();
38              match (value, &access) {
39                  (ArgumentRefType::Plaintext(Plaintext::Struct(members, ..)), Access::Member(identifier)) => {
40                      match members.get(identifier) {
41                          // Retrieve the member and update `value` for the next iteration.
42                          Some(member) => value = ArgumentRefType::Plaintext(member),
43                          // Halts if the member does not exist.
44                          None => bail!("Failed to locate member '{identifier}''"),
45                      }
46                  }
47                  (ArgumentRefType::Plaintext(Plaintext::Array(array, ..)), Access::Index(index)) => {
48                      let index = match index.eject_mode() {
49                          Mode::Constant => index.eject_value(),
50                          _ => bail!("'{index}' must be a constant"),
51                      };
52                      match array.get(*index as usize) {
53                          // Retrieve the element and update `value` for the next iteration.
54                          Some(element) => value = ArgumentRefType::Plaintext(element),
55                          // Halts if the index is out of bounds.
56                          None => bail!("Index '{index}' is out of bounds"),
57                      }
58                  }
59                  (ArgumentRefType::Future(future), Access::Index(index)) => {
60                      let index = match index.eject_mode() {
61                          Mode::Constant => index.eject_value(),
62                          _ => bail!("'{index}' must be a constant"),
63                      };
64                      match future.arguments.get(*index as usize) {
65                          // If the argument is a future, update `value` for the next iteration.
66                          Some(Argument::Future(future)) => value = ArgumentRefType::Future(future),
67                          // If the argument is a plaintext, update `value` for the next iteration.
68                          Some(Argument::Plaintext(plaintext)) => value = ArgumentRefType::Plaintext(plaintext),
69                          // Halts if the index is out of bounds.
70                          None => bail!("Index '{index}' is out of bounds"),
71                      }
72                  }
73                  _ => bail!("Invalid access `{access}`"),
74              }
75          }
76  
77          match value {
78              ArgumentRefType::Plaintext(plaintext) => Ok(Value::Plaintext(plaintext.clone())),
79              ArgumentRefType::Future(future) => Ok(Value::Future(future.clone())),
80          }
81      }
82  }