Implement function value

src/interface.rs

@@ -1,5 +1,6 @@
 //! The top level of Dust's API with functions to interpret Dust code.
 
+use serde::{Deserialize, Serialize};
 use tree_sitter::{Node, Parser, Tree as TSTree, TreeCursor};
 
 use crate::{language, Error, Result, Value, VariableMap};
@@ -170,7 +171,7 @@ impl Item {
 /// Items are either comments, which do nothing, or statements, which can be run
 /// to produce a single value or interact with a context by creating or
 /// referencing variables.
-#[derive(Debug)]
+#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq, PartialOrd, Ord)]
 pub enum Statement {
     Open(Expression),
 }
@@ -205,7 +206,7 @@ impl Statement {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq, PartialOrd, Ord)]
 pub enum Expression {
     Identifier(String),
     Value(Value),
@@ -267,7 +268,7 @@ impl Expression {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq, PartialOrd, Ord)]
 pub struct Operation {
     left: Expression,
     operator: String,
@@ -298,7 +299,8 @@ impl Operation {
     ) -> Result<Value> {
         let left = self.left.run(context, &mut cursor, source)?;
         let right = self.right.run(context, &mut cursor, source)?;
-        let result = match self.operator.as_str() {
+
+        match self.operator.as_str() {
             "+" => left + right,
             "-" => left - right,
             "=" => {
@@ -309,10 +311,8 @@ impl Operation {
                 Ok(Value::Empty)
             }
             "==" => Ok(Value::Boolean(left == right)),
-            _ => return Err(Error::CustomMessage("Operator not supported.".to_string())),
-        };
-
-        Ok(result?)
+            _ => Err(Error::CustomMessage("Operator not supported.".to_string())),
+        }
     }
 }
 
@@ -320,7 +320,7 @@ impl Operation {
 ///
 /// A ControlFlow instance represents work to be done when the "run" method is
 /// called.
-#[derive(Debug)]
+#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq, PartialOrd, Ord)]
 pub struct ControlFlow {
     if_expression: Expression,
     then_statement: Statement,
@@ -369,7 +369,7 @@ impl ControlFlow {
 
 #[cfg(test)]
 mod tests {
-    use crate::{Function, Table};
+    use crate::Table;
 
     use super::*;
 
@@ -416,17 +416,6 @@ mod tests {
         );
     }
 
-    #[test]
-    fn evaluate_function() {
-        let function_str = "function <message, number> {
-            output message
-            output number
-        }";
-
-        todo!();
-        // assert_eq!("", vec![Ok(Value::Function(Function::new(function_str)))]);
-    }
-
     #[test]
     fn evaluate_map() {
         let mut map = VariableMap::new();

src/value/function.rs

@@ -2,14 +2,20 @@ use std::fmt::{self, Display, Formatter};
 
 use serde::{Deserialize, Serialize};
 
-use crate::{eval, eval_with_context, Result, Value, VariableMap};
+use crate::{Result, Statement, Value, VariableMap};
 
-#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
-pub struct Function(String);
+#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq, PartialOrd, Ord)]
+pub struct Function {
+    identifiers: Vec<String>,
+    statements: Vec<Statement>,
+}
 
 impl Function {
-    pub fn new(body: &str) -> Self {
-        Function(body.to_string())
+    pub fn new(identifiers: Vec<String>, statements: Vec<Statement>) -> Self {
+        Function {
+            identifiers,
+            statements,
+        }
     }
 
     pub fn run(&self) -> Result<Value> {
@@ -23,6 +29,10 @@ impl Function {
 
 impl Display for Function {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
-        write!(f, "{}", self.0)
+        write!(
+            f,
+            "function < {:?} > {{ {:?} }}",
+            self.identifiers, self.statements
+        )
     }
 }

src/value/mod.rs

@@ -1,7 +1,7 @@
 //! Types that represent runtime values.
 use crate::{
     error::{Error, Result},
-    Expression, Function, Table, Time, ValueType, VariableMap,
+    Expression, Function, Statement, Table, Time, ValueType, VariableMap,
 };
 
 use json::JsonValue;
@@ -134,6 +134,31 @@ impl Value {
                 Ok(Value::Table(table))
             }
             "map" => todo!(),
+            "function" => {
+                let child_count = node.child_count();
+                let mut identifiers = Vec::new();
+                let mut statements = Vec::new();
+
+                for index in 0..child_count {
+                    let child = node.child(index).unwrap();
+
+                    if child.kind() == "identifier" {
+                        let child_identifier = Expression::new(child, source)?;
+
+                        if let Expression::Identifier(identifier) = child_identifier {
+                            identifiers.push(identifier)
+                        }
+                    }
+
+                    if child.kind() == "statement" {
+                        let statement = Statement::new(child, source)?;
+
+                        statements.push(statement)
+                    }
+                }
+
+                Ok(Value::Function(Function::new(identifiers, statements)))
+            }
             "empty" => Ok(Value::Empty),
             _ => Err(Error::UnexpectedSourceNode {
                 expected: "integer, string, boolean, float, list or empty",