Add while loop support and token pretty printing

The commit adds while loop statements and improves token display
formatting:

- Implements while loop syntax and evaluation - Adds a new token pretty
printing module with configurable formatting - Improves token display
with colors and different output modes

src/frontend/ast.rs

@@ -19,6 +19,7 @@ use std::fmt::{Debug, Display};
  * assignment_statement -> IDENTIFIER "=" expression ";"
  * block_statement -> "do" statement* "end"
  * if_statement -> "if" expression "then" statement ("elif" expression "then" statement)* ("else" statement)? "end"
+ * while_statement -> "while" expression "do" statement "end"
  *
  * expression -> assignment
  * assignment -> IDENTIFIER "=" assignment | logical_or
@@ -145,6 +146,15 @@ pub enum Stmt {
         elif_branch: Vec<(Box<Expr>, Box<Stmt>)>,
         else_branch: Option<Box<Stmt>>,
     },
+    While {
+        condition: Box<Expr>,
+        body: Box<Stmt>,
+    },
+    For {
+        variable: Box<Expr>,
+        iterable: Box<Expr>,
+        body: Box<Stmt>,
+    },
 }
 
 impl Display for Stmt {
@@ -182,6 +192,12 @@ impl Display for Stmt {
                     .collect::<Vec<_>>()
                     .join("\n")
             ),
+            Stmt::While { condition, body } => todo!(),
+            Stmt::For {
+                variable,
+                iterable,
+                body,
+            } => todo!(),
         }
     }
 }
@@ -221,6 +237,12 @@ impl Debug for Stmt {
                     .collect::<Vec<_>>()
                     .join("\t\t\n")
             ),
+            Stmt::While { condition, body } => todo!(),
+            Stmt::For {
+                variable,
+                iterable,
+                body,
+            } => todo!(),
         }
     }
 }
@@ -267,6 +289,12 @@ impl AstNodeKind for Stmt {
             } => "if statement",
             Stmt::Print { expression: _ } => "print statement",
             Stmt::Stmt { expression: _ } => "statement",
+            Stmt::While { condition, body } => todo!(),
+            Stmt::For {
+                variable,
+                iterable,
+                body,
+            } => todo!(),
         }
     }
 }

src/frontend/lexer.rs

@@ -1,5 +1,6 @@
 use crate::frontend::source_registry::{SourceId, SourcePosition, SourceSlice};
 use crate::frontend::tokens::{LiteralValue, Token, TokenType};
+use crate::logging::display_token::TokenPrettyPrintExt;
 use crate::result::{LoxError, LoxResult};
 
 pub struct Lexer {
@@ -74,7 +75,7 @@ impl Lexer {
         }
         tokens.push(self.make_token(TokenType::Eof));
         println!("Tokens:");
-        tokens.iter().for_each(|val| println!("{}", val));
+        tokens.iter().for_each(|val| println!("{}", val.pretty()));
         Ok(tokens)
     }
 

src/frontend/parser.rs

@@ -81,6 +81,10 @@ impl Parser {
                 self.if_statement()?,
                 self.peek().source_slice.clone(),
             )),
+            (TokenType::While, _) => Ok(AstNode::new(
+                self.while_statement()?,
+                self.peek().source_slice.clone(),
+            )),
             _ => Ok(AstNode::new(
                 self.expression_statement()?,
                 self.peek().source_slice.clone(),
@@ -88,6 +92,16 @@ impl Parser {
         }
     }
 
+    fn while_statement(&mut self) -> LoxResult<Stmt> {
+        self.advance();
+        let condition = self.expression()?;
+        let body = self.block_statement()?;
+        Ok(Stmt::While {
+            condition: Box::new(condition),
+            body: Box::new(body),
+        })
+    }
+
     fn if_statement(&mut self) -> LoxResult<Stmt> {
         self.advance();
         let condition = self.expression()?;