From 12f476800868dc0587073b77e25fc46178d48cd5 Mon Sep 17 00:00:00 2001
From: KtorZ <matthias.benkort@gmail.com>
Date: Sat, 4 Feb 2023 10:22:23 +0100
Subject: [PATCH] Write method to apply a UPLC term to an existing 'Validator'

---
 crates/aiken-project/src/blueprint/error.rs     |  6 ++++++
 crates/aiken-project/src/blueprint/validator.rs | 14 +++++++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/crates/aiken-project/src/blueprint/error.rs b/crates/aiken-project/src/blueprint/error.rs
index f9acdb29..a7f93555 100644
--- a/crates/aiken-project/src/blueprint/error.rs
+++ b/crates/aiken-project/src/blueprint/error.rs
@@ -27,6 +27,7 @@ pub enum Error {
         source_code: NamedSource,
         return_type: Arc<Type>,
     },
+
     #[error("A {} validator requires at least {} arguments.", name.purple().bold(), at_least.to_string().purple().bold())]
     #[diagnostic(code("aiken::blueprint::invalid::arity"))]
     WrongValidatorArity {
@@ -37,6 +38,7 @@ pub enum Error {
         #[source_code]
         source_code: NamedSource,
     },
+
     #[error("{}", error)]
     #[diagnostic(help("{}", error.help()))]
     #[diagnostic(code("aiken::blueprint::interface"))]
@@ -52,6 +54,10 @@ pub enum Error {
     #[diagnostic(code("aiken::blueprint::missing"))]
     #[diagnostic(help("Did you forget to {build} the project?", build = "build".purple().bold()))]
     InvalidOrMissingFile,
+
+    #[error("I didn't find any parameters to apply in the given validator.")]
+    #[diagnostic(code("aiken::blueprint::apply::no_parameters"))]
+    NoParametersToApply,
 }
 
 pub fn assert_return_bool(module: &CheckedModule, def: &TypedFunction) -> Result<(), Error> {
diff --git a/crates/aiken-project/src/blueprint/validator.rs b/crates/aiken-project/src/blueprint/validator.rs
index faf7b229..aef9a368 100644
--- a/crates/aiken-project/src/blueprint/validator.rs
+++ b/crates/aiken-project/src/blueprint/validator.rs
@@ -10,7 +10,7 @@ use std::{
     collections::HashMap,
     fmt::{self, Display},
 };
-use uplc::ast::{DeBruijn, Program};
+use uplc::ast::{DeBruijn, Program, Term};
 
 #[derive(Debug, PartialEq, Clone, serde::Serialize, serde::Deserialize)]
 pub struct Validator<T> {
@@ -122,6 +122,18 @@ impl Validator<Schema> {
                 .unwrap(),
         })
     }
+
+    pub fn apply(&mut self, arg: &Term<DeBruijn>) -> Result<(), Error> {
+        match self.parameters.split_first() {
+            None => Err(Error::NoParametersToApply),
+            Some((_, tail)) => {
+                // TODO: Ideally, we should control that the applied term matches its schema.
+                self.program = self.program.apply_term(arg);
+                self.parameters = tail.to_vec();
+                Ok(())
+            }
+        }
+    }
 }
 
 impl Purpose {