Improve AST construction and errors

src/error.rs

@@ -2,6 +2,7 @@
 //!
 //! To deal with errors from dependencies, either create a new error variant
 //! or use the MacroFailure variant if the error can only occur inside a macro.
+
 use crate::{value::value_type::ValueType, value::Value, ToolInfo};
 
 use std::{fmt, io, time::SystemTimeError};
@@ -18,6 +19,10 @@ pub enum Error {
 
     ExpectedFieldName,
 
+    ExpectedChildNode {
+        empty_node_sexp: String,
+    },
+
     /// Dust's internal type checking failed to identify a type mismatch. This should never happen,      /// the error prompts the user to report the bug.
     TypeCheckFailure {
         tool_info: ToolInfo<'static>,
@@ -290,14 +295,6 @@ impl From<toml::de::Error> for Error {
 }
 
 impl Error {
-    pub(crate) fn expect_operator_argument_amount(actual: usize, expected: usize) -> Result<()> {
-        if actual == expected {
-            Ok(())
-        } else {
-            Err(Error::ExpectedOperatorArgumentAmount { expected, actual })
-        }
-    }
-
     pub(crate) fn expect_function_argument_amount(
         identifier: &str,
         actual: usize,
@@ -389,36 +386,6 @@ impl Error {
         Error::ExpectedCollection { actual }
     }
 
-    pub(crate) fn addition_error(augend: Value, addend: Value) -> Self {
-        Error::AdditionError { augend, addend }
-    }
-
-    pub(crate) fn subtraction_error(minuend: Value, subtrahend: Value) -> Self {
-        Error::SubtractionError {
-            minuend,
-            subtrahend,
-        }
-    }
-
-    pub(crate) fn negation_error(argument: Value) -> Self {
-        Error::NegationError { argument }
-    }
-
-    pub(crate) fn multiplication_error(multiplicand: Value, multiplier: Value) -> Self {
-        Error::MultiplicationError {
-            multiplicand,
-            multiplier,
-        }
-    }
-
-    pub(crate) fn division_error(dividend: Value, divisor: Value) -> Self {
-        Error::DivisionError { dividend, divisor }
-    }
-
-    pub(crate) fn modulation_error(dividend: Value, divisor: Value) -> Self {
-        Error::ModulationError { dividend, divisor }
-    }
-
     /// Constructs `EvalexprError::InvalidRegex(regex)`
     pub fn invalid_regex(regex: String, message: String) -> Self {
         Error::InvalidRegex { regex, message }
@@ -588,6 +555,7 @@ impl fmt::Display for Error {
             UnexpectedSourceNode { expected, actual } => write!(f, "Unexpected source node. Expected {expected}, but found {actual}."),
             ExpectedFieldName => write!(f, "Expected a field name for this node, but none was found."),
             WrongTypeCombination { expected, actual } => write!(f, "Wrong type combination. Expected {expected}, found {actual}."),
+            ExpectedChildNode { empty_node_sexp } => write!(f, "Expected this node to have a child, {empty_node_sexp}."),
         }
     }
 }

src/interface.rs

@@ -1,5 +1,6 @@
 //! The top level of Dust's API with functions to interpret Dust code.
 
+use egui::util::id_type_map;
 use tree_sitter::{Node, Parser, Tree, TreeCursor};
 
 use crate::{language, Error, Result, Value, VariableMap};
@@ -33,11 +34,11 @@ pub fn eval(source: &str) -> Vec<Result<Value>> {
 /// context.set_value("two".into(), 2.into()).unwrap(); // Do proper error handling here
 /// context.set_value("three".into(), 3.into()).unwrap(); // Do proper error handling here
 ///
-/// let dust_code = "one + two + three; one - two - three;";
+/// let dust_code = "four = 4; one + two + three + four;";
 ///
 /// assert_eq!(
 ///     eval_with_context(dust_code, &mut context),
-///     vec![Ok(Value::from(6)), Ok(Value::from(-4))]
+///     vec![Ok(Value::Empty), Ok(Value::from(10))]
 /// );
 /// ```
 pub fn eval_with_context(source: &str, context: &mut VariableMap) -> Vec<Result<Value>> {
@@ -74,10 +75,18 @@ struct Evaluator {
 impl Evaluator {
     fn new(tree: Tree, source: &str) -> Result<Self> {
         let root_node = tree.root_node();
+        let mut cursor = tree.walk();
         let mut items = Vec::new();
 
-        let item = Item::new(root_node, source)?;
+        for (index, node) in root_node.children(&mut cursor).enumerate() {
-        items.push(item);
+            let item = Item::new(node, source)?;
+
+            items.push(item);
+
+            if index == root_node.child_count() - 1 {
+                break;
+            }
+        }
 
         Ok(Evaluator { items })
     }
@@ -150,9 +159,14 @@ enum Statement {
 
 impl Statement {
     fn new(node: Node, source: &str) -> Result<Self> {
+        let node = if node.kind() == "statement" {
+            node.child(0).unwrap()
+        } else {
+            node
+        };
         let child = node.child(0).unwrap();
 
-        match child.kind() {
+        match node.kind() {
             "closed_statement" => Ok(Statement::Closed(Expression::new(child, source)?)),
             "open_statement" => Ok(Self::Open(Expression::new(child, source)?)),
             _ => Err(Error::UnexpectedSourceNode {
@@ -189,31 +203,31 @@ enum Expression {
 
 impl Expression {
     fn new(node: Node, source: &str) -> Result<Self> {
-        let mut child = node.child(0).unwrap();
+        let node = if node.kind() == "expression" {
+            node.child(0).unwrap()
+        } else {
+            node
+        };
 
-        if child.kind() == "expression" {
+        if node.kind() == "identifier" {
-            child = child.child(0).unwrap();
+            let byte_range = node.byte_range();
-        }
-
-        if child.kind() == "identifier" {
-            let byte_range = child.byte_range();
             let identifier = &source[byte_range];
 
             Ok(Self::Identifier(identifier.to_string()))
-        } else if child.kind() == "value" {
+        } else if node.kind() == "value" {
-            Ok(Expression::Value(Value::new(child, source)?))
+            Ok(Expression::Value(Value::new(node, source)?))
-        } else if child.kind() == "operation" {
+        } else if node.kind() == "operation" {
             Ok(Expression::Operation(Box::new(Operation::new(
-                child, source,
+                node, source,
             )?)))
-        } else if child.kind() == "control_flow" {
+        } else if node.kind() == "control_flow" {
             Ok(Expression::ControlFlow(Box::new(ControlFlow::new(
-                child, source,
+                node, source,
             )?)))
         } else {
             Err(Error::UnexpectedSourceNode {
                 expected: "identifier, operation, control_flow or value",
-                actual: child.kind(),
+                actual: node.kind(),
             })
         }
     }

src/value/mod.rs

@@ -314,7 +314,7 @@ impl Sub for Value {
 
                 Ok(Value::Float(addition))
             }
-            (Value::Float(_), other) | (other, Value::Float(_)) => Err(Error::ExpectedFloat {
+            (Value::Float(_), other) | (other, Value::Float(_)) => Err(Error::ExpectedNumber {
                 actual: other.clone(),
             }),
             (Value::Integer(left), Value::Integer(right)) => Ok(Value::Integer(left - right)),