Indexing matrices by ⟦⟧

kalk/src/ast.rs

@@ -23,7 +23,7 @@ pub enum Expr {
     Piecewise(Vec<ConditionalPiece>),
     Vector(Vec<Expr>),
     Matrix(Vec<Vec<Expr>>),
-    Indexer(Box<Expr>, Box<Expr>),
+    Indexer(Box<Expr>, Vec<Expr>),
 }
 
 #[derive(Debug, Clone, PartialEq)]

kalk/src/interpreter.rs

@@ -126,7 +126,7 @@ pub(crate) fn eval_expr(
         Expr::Piecewise(pieces) => eval_piecewise(context, pieces, unit),
         Expr::Vector(values) => eval_vector(context, values),
         Expr::Matrix(rows) => eval_matrix(context, rows),
-        Expr::Indexer(var, index) => eval_indexer(context, var, index, unit),
+        Expr::Indexer(var, indexes) => eval_indexer(context, var, indexes, unit),
     }
 }
 
@@ -582,19 +582,42 @@ fn eval_matrix(context: &mut Context, rows: &Vec<Vec<Expr>>) -> Result<KalkValue
 fn eval_indexer(
     context: &mut Context,
     var: &Expr,
-    index: &Expr,
+    indexes: &[Expr],
     unit: &str,
 ) -> Result<KalkValue, CalcError> {
     let var_value = eval_expr(context, var, unit)?;
-    if let KalkValue::Vector(values) = var_value {
-        let index_value = eval_expr(context, index, unit)?.to_f64() as usize;
-        if let Some(value) = values.get(index_value) {
-            Ok(value.clone())
-        } else {
-            Err(CalcError::ItemOfIndexDoesNotExist(index_value))
+    match var_value {
+        KalkValue::Vector(values) => {
+            if indexes.len() != 1 {
+                return Err(CalcError::IncorrectAmountOfIndexes(indexes.len(), 1));
+            }
+
+            let index_value = eval_expr(context, &indexes[0], unit)?.to_f64() as usize;
+            if let Some(value) = values.get(index_value) {
+                Ok(value.clone())
+            } else {
+                Err(CalcError::ItemOfIndexDoesNotExist(vec![index_value]))
+            }
         }
-    } else {
-        Err(CalcError::CanOnlyIndexVectors)
+        KalkValue::Matrix(rows) => {
+            if indexes.len() != 2 {
+                return Err(CalcError::IncorrectAmountOfIndexes(indexes.len(), 2));
+            }
+
+            let row_index = eval_expr(context, &indexes[0], unit)?.to_f64() as usize;
+            let column_index = eval_expr(context, &indexes[1], unit)?.to_f64() as usize;
+            if let Some(row) = rows.get(row_index) {
+                if let Some(value) = row.get(column_index) {
+                    return Ok(value.clone());
+                }
+            }
+
+            Err(CalcError::ItemOfIndexDoesNotExist(vec![
+                row_index,
+                column_index,
+            ]))
+        }
+        _ => Err(CalcError::CanOnlyIndexVectors),
     }
 }
 

kalk/src/parser.rs

@@ -104,7 +104,8 @@ pub enum CalcError {
     ExpectedDx,
     ExpectedIf,
     IncorrectAmountOfArguments(usize, String, usize),
-    ItemOfIndexDoesNotExist(usize),
+    IncorrectAmountOfIndexes(usize, usize),
+    ItemOfIndexDoesNotExist(Vec<usize>),
     InconsistentColumnWidths,
     InvalidNumberLiteral(String),
     InvalidOperator,
@@ -134,7 +135,11 @@ impl ToString for CalcError {
                 "Expected {} arguments for function {}, but got {}.",
                 expected, func, got
             ),
-            CalcError::ItemOfIndexDoesNotExist(index) => format!("Item of index {} does not exist.", index),
+            CalcError::IncorrectAmountOfIndexes(expected,  got) => format!(
+                "Expected {} indexes but got {}.",
+                expected, got
+            ),
+            CalcError::ItemOfIndexDoesNotExist(indexes) => format!("Item of index ⟦{}⟧ does not exist.", indexes.iter().map(|x| x.to_string()).collect::<Vec<String>>().join(", ")),
             CalcError::InconsistentColumnWidths => format!("Inconsistent column widths. Matrix columns must be the same size."),
             CalcError::InvalidNumberLiteral(x) => format!("Invalid number literal: '{}'.", x),
             CalcError::InvalidOperator => format!("Invalid operator."),
@@ -566,9 +571,15 @@ fn parse_indexer(context: &mut Context) -> Result<Expr, CalcError> {
 
     if match_token(context, TokenKind::OpenDoubleBracket) {
         advance(context);
-        let right = Box::new(parse_expr(context)?);
+        let mut indexes = vec![parse_expr(context)?];
+        while match_token(context, TokenKind::Comma) {
+            advance(context);
+            indexes.push(parse_expr(context)?);
+        }
+
         consume(context, TokenKind::ClosedDoubleBracket)?;
-        return Ok(Expr::Indexer(Box::new(left), right));
+
+        return Ok(Expr::Indexer(Box::new(left), indexes));
     }
 
     Ok(left)
@@ -771,7 +782,7 @@ fn parse_identifier(context: &mut Context) -> Result<Expr, CalcError> {
 
         Ok(Expr::Indexer(
             Box::new(Expr::Var(Identifier::from_full_name(&var_name))),
-            Box::new(lowered_expr),
+            vec![lowered_expr],
         ))
     } else if context.parsing_unit_decl {
         context.unit_decl_base_unit = Some(identifier.full_name);