Vector indexing with lowered numbers, eg. v_1

cli/src/repl.rs

@@ -201,7 +201,7 @@ impl Completer for RLHelper {
             }
 
             if subscript_digits.len() > 0 {
-                let value = kalk::text_utils::digits_to_subscript(subscript_digits.chars());
+                let value = kalk::text_utils::normal_to_subscript(subscript_digits.chars());
                 return Ok((pos - subscript_digits.chars().count() - 1, vec![value]));
             }
         }

kalk/src/ast.rs

@@ -22,6 +22,7 @@ pub enum Expr {
     Literal(f64),
     Piecewise(Vec<ConditionalPiece>),
     Vector(Vec<Expr>),
+    Indexer(Box<Expr>, Box<Expr>),
 }
 
 #[derive(Debug, Clone, PartialEq)]
@@ -67,6 +68,14 @@ impl Identifier {
             prime_count: 0u32,
         }
     }
+
+    pub fn get_name_without_lowered(&self) -> &str {
+        if let Some(underscore_pos) = self.pure_name.find('_') {
+            &self.pure_name[0..underscore_pos]
+        } else {
+            &self.pure_name
+        }
+    }
 }
 
 pub fn build_literal_ast(kalk_value: &crate::kalk_value::KalkValue) -> Expr {

kalk/src/interpreter.rs

@@ -125,6 +125,7 @@ pub(crate) fn eval_expr(
         }
         Expr::Piecewise(pieces) => eval_piecewise(context, pieces, unit),
         Expr::Vector(values) => eval_vector(context, values),
+        Expr::Indexer(var, index) => eval_indexer(context, var, index, unit),
     }
 }
 
@@ -250,9 +251,10 @@ fn eval_var_expr(
         .symbol_table
         .get_var(identifier.full_name.as_ref() as &str)
         .cloned();
-    match var_decl {
+    if let Some(Stmt::VarDecl(_, expr)) = var_decl {
-        Some(Stmt::VarDecl(_, expr)) => eval_expr(context, &expr, unit),
+        eval_expr(context, &expr, unit)
-        _ => Err(CalcError::UndefinedVar(identifier.full_name.clone())),
+    } else {
+        Err(CalcError::UndefinedVar(identifier.full_name.clone()))
     }
 }
 
@@ -534,6 +536,25 @@ fn eval_vector(context: &mut Context, values: &Vec<Expr>) -> Result<KalkValue, C
     Ok(KalkValue::Vector(eval_values))
 }
 
+fn eval_indexer(
+    context: &mut Context,
+    var: &Expr,
+    index: &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))
+        }
+    } else {
+        Err(CalcError::CanOnlyIndexVectors)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

kalk/src/inverter.rs

@@ -88,6 +88,7 @@ fn invert(
         Expr::Literal(_) => Ok((target_expr, expr.clone())),
         Expr::Piecewise(_) => Err(CalcError::UnableToInvert(String::from("Piecewise"))),
         Expr::Vector(_) => Err(CalcError::UnableToInvert(String::from("Vector"))),
+        Expr::Indexer(_, _) => Err(CalcError::UnableToInvert(String::from("Inverter"))),
     }
 }
 
@@ -390,6 +391,7 @@ pub fn contains_var(symbol_table: &SymbolTable, expr: &Expr, var_name: &str) ->
         Expr::Vector(items) => items
             .iter()
             .any(|x| contains_var(symbol_table, x, var_name)),
+        Expr::Indexer(_, _) => false,
     }
 }
 

kalk/src/lexer.rs

@@ -241,7 +241,7 @@ impl<'a> Lexer<'a> {
         }
 
         if base_str != "" {
-            base = crate::text_utils::subscript_to_digits(base_str.chars())
+            base = crate::text_utils::subscript_to_normal(base_str.chars())
                 .parse::<u8>()
                 .unwrap_or(10);
         }
@@ -266,6 +266,7 @@ impl<'a> Lexer<'a> {
         let start = self.index;
         let mut end = start;
         let mut value = String::new();
+        let mut subscript = String::new();
 
         while is_valid_identifier(self.peek()) {
             let c = *self.peek().unwrap();
@@ -292,8 +293,13 @@ impl<'a> Lexer<'a> {
                 break;
             }
 
-            end += 1;
+            if is_subscript(&c) {
+                subscript.push(c);
+            } else {
                 value.push(c);
+            }
+
+            end += 1;
             self.advance();
         }
 
@@ -323,11 +329,23 @@ impl<'a> Lexer<'a> {
             "sech⁻¹" => String::from("asech"),
             "∛" => String::from("cbrt"),
             "°" => String::from("deg"),
-            _ => value, // things like log₂ are handled in the parser
+            _ => value, // things like log_2 are handled in the parser
         };
 
+        if subscript.len() > 0 {
+            build(
+                kind,
+                &format!(
+                    "{}_{}",
+                    value,
+                    crate::text_utils::subscript_to_normal(subscript.chars())
+                ),
+                (start, end),
+            )
+        } else {
             build(kind, &value, (start, end))
         }
+    }
 
     fn peek(&mut self) -> Option<&char> {
         self.chars.peek()

kalk/src/parser.rs

@@ -14,6 +14,7 @@ pub const DEFAULT_ANGLE_UNIT: &'static str = "rad";
 
 /// Struct containing the current state of the parser. It stores user-defined functions and variables.
 #[wasm_bindgen]
+#[derive(Clone)]
 pub struct Context {
     tokens: Vec<Token>,
     pos: usize,
@@ -99,10 +100,12 @@ impl Default for Context {
 /// Error that occured during parsing or evaluation.
 #[derive(Debug, Clone, PartialEq)]
 pub enum CalcError {
+    CanOnlyIndexVectors,
     Expected(String),
     ExpectedDx,
     ExpectedIf,
     IncorrectAmountOfArguments(usize, String, usize),
+    ItemOfIndexDoesNotExist(usize),
     InvalidNumberLiteral(String),
     InvalidOperator,
     InvalidUnit,
@@ -123,6 +126,7 @@ pub enum CalcError {
 impl ToString for CalcError {
     fn to_string(&self) -> String {
         match self {
+            CalcError::CanOnlyIndexVectors => format!("Indexing (getting an item with a specific index) is only possible on vectors."),
             CalcError::Expected(description) => format!("Expected: {}", description),
             CalcError::ExpectedDx => format!("Expected eg. dx, to specify for which variable the operation is being done to. Example with integration: ∫(0, 1, x dx) or ∫(0, 1, x, dx). You may need to put parenthesis around the expression before dx/dy/du/etc."),
             CalcError::ExpectedIf => format!("Expected 'if', with a condition after it."),
@@ -130,6 +134,7 @@ 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::InvalidNumberLiteral(x) => format!("Invalid number literal: '{}'.", x),
             CalcError::InvalidOperator => format!("Invalid operator."),
             CalcError::InvalidUnit => format!("Invalid unit."),
@@ -607,7 +612,7 @@ fn parse_vector(context: &mut Context) -> Result<Expr, CalcError> {
 
     if peek(context).kind == TokenKind::EOF {
         return Err(CalcError::Expected(String::from(
-            "Closing group symbol, eg. ⌋",
+            "Closing group symbol, eg. )",
         )));
     }
 
@@ -626,7 +631,7 @@ fn parse_identifier(context: &mut Context) -> Result<Expr, CalcError> {
     let mut log_base = None;
     if identifier.full_name.starts_with("log") {
         if let Some(c) = identifier.full_name.chars().nth(3) {
-            if crate::text_utils::is_subscript(&c) {
+            if c == '_' {
                 log_base = Some(Expr::Literal(get_base(&identifier.full_name)? as f64));
             }
         }
@@ -700,6 +705,28 @@ fn parse_identifier(context: &mut Context) -> Result<Expr, CalcError> {
     // Eg. x
     if parse_as_var_instead || context.symbol_table.contains_var(&identifier.pure_name) {
         Ok(build_var(context, &identifier.full_name))
+    } else if context
+        .symbol_table
+        .contains_var(&identifier.get_name_without_lowered())
+    {
+        let underscore_pos = identifier.pure_name.find('_').unwrap();
+        let var_name = &identifier.pure_name[0..underscore_pos];
+        let lowered = &identifier.pure_name[underscore_pos + 1..];
+
+        // Create a new identical context to avoid changing the current one
+        let mut lowered_context = context.clone();
+        let mut parsed_stmts = parse(&mut lowered_context, &lowered)?;
+        let parsed_lowered = parsed_stmts
+            .pop()
+            .unwrap_or(Stmt::Expr(Box::new(Expr::Literal(0f64))));
+        if let Stmt::Expr(lowered_expr) = parsed_lowered {
+            Ok(Expr::Indexer(
+                Box::new(Expr::Var(Identifier::from_full_name(&var_name))),
+                lowered_expr,
+            ))
+        } else {
+            Err(CalcError::UnableToParseExpression)
+        }
     } else if context.parsing_unit_decl {
         context.unit_decl_base_unit = Some(identifier.full_name);
         Ok(Expr::Var(Identifier::from_full_name(DECL_UNIT)))

kalk/src/radix.rs

@@ -65,7 +65,7 @@ pub fn to_radix_pretty(value: f64, radix: u8) -> String {
         format!(
             "{}{}",
             float_to_radix(value, radix),
-            crate::text_utils::digits_to_subscript(radix.to_string().chars())
+            crate::text_utils::normal_to_subscript(radix.to_string().chars())
         )
     }
 }

kalk/src/symbol_table.rs

@@ -1,7 +1,7 @@
 use crate::{ast::Expr, ast::Identifier, ast::Stmt, prelude};
 use std::collections::HashMap;
 
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct SymbolTable {
     pub(crate) hashmap: HashMap<String, Stmt>,
     pub(crate) unit_types: HashMap<String, ()>,

kalk/src/text_utils.rs

@@ -9,22 +9,21 @@ pub fn is_superscript(c: &char) -> bool {
 
 pub fn is_subscript(c: &char) -> bool {
     match c {
-        '₀' | '₁' | '₂' | '₃' | '₄' | '₅' | '₆' | '₇' | '₈' | '₉' | '₊' | '₋' | '₌' | '₍' | '₎' => {
+        '₀' | '₁' | '₂' | '₃' | '₄' | '₅' | '₆' | '₇' | '₈' | '₉' | '₊' | '₋' | '₌' | '₍' | '₎'
-            true
+        | 'ₖ' | 'ₗ' | 'ₘ' | 'ₙ' | 'ₓ' => true,
-        }
         _ => false,
     }
 }
 
 pub fn parse_subscript(chars: impl Iterator<Item = char>) -> Option<u8> {
-    if let Ok(result) = subscript_to_digits(chars).parse::<u8>() {
+    if let Ok(result) = subscript_to_normal(chars).parse::<u8>() {
         Some(result)
     } else {
         None
     }
 }
 
-pub fn subscript_to_digits(chars: impl Iterator<Item = char>) -> String {
+pub fn subscript_to_normal(chars: impl Iterator<Item = char>) -> String {
     let mut regular = String::new();
     for c in chars {
         regular.push(match c {
@@ -43,6 +42,11 @@ pub fn subscript_to_digits(chars: impl Iterator<Item = char>) -> String {
             '₌' => '=',
             '₍' => '(',
             '₎' => ')',
+            'ₖ' => 'k',
+            'ₗ' => 'l',
+            'ₘ' => 'm',
+            'ₙ' => 'n',
+            'ₓ' => 'x',
             _ => c,
         });
     }
@@ -50,7 +54,7 @@ pub fn subscript_to_digits(chars: impl Iterator<Item = char>) -> String {
     return regular.trim().to_string();
 }
 
-pub fn digits_to_subscript(chars: impl Iterator<Item = char>) -> String {
+pub fn normal_to_subscript(chars: impl Iterator<Item = char>) -> String {
     let mut subscript = String::new();
     for c in chars {
         subscript.push(match c {
@@ -69,6 +73,11 @@ pub fn digits_to_subscript(chars: impl Iterator<Item = char>) -> String {
             '=' => '₌',
             '(' => '₍',
             ')' => '₎',
+            'k' => 'ₖ',
+            'l' => 'ₗ',
+            'm' => 'ₘ',
+            'n' => 'ₙ',
+            'x' => 'ₓ',
             _ => c,
         });
     }