wip AST generation

src/parser/mod.rs

@@ -1,135 +1,210 @@
-use thiserror::Error;
+mod tree_node;
 
 use crate::tokenizer::{
-    token::{Keyword, Number, Symbol, Token, TokenType},
+    token::{Symbol, Token, TokenType},
     Tokenizer, TokenizerError,
 };
-use std::io::{Read, Seek};
+use std::{
+    collections::VecDeque,
+    io::{Read, Seek},
+};
+use thiserror::Error;
+use tree_node::*;
 
 #[derive(Debug, Error)]
 pub enum ParseError {
-    #[error("{0}")]
+    #[error(transparent)]
     TokenizerError(#[from] TokenizerError),
-    #[error("Unexpected EOF\n\nLine: {0}, Column: {1}", token.line, token.column)]
-    UnexpectedEOF { token: Token },
     #[error("Unexpected token\n\nLine: {0}, Column: {1}\nToken: {2}", token.line, token.column, token.token_type)]
     UnexpectedToken { token: Token },
+    #[error("Unexpected EOF")]
+    UnexpectedEOF,
     #[error("An unknown error has occurred")]
     UnknownError,
 }
 
-#[derive(Debug)]
+pub struct Parser<R: Read + Seek> {
-enum Literal {
+    tokenizer: Tokenizer<R>,
-    Number(Number),
+    current_token: Option<Token>,
-    String(String),
-    Boolean(bool),
 }
 
-#[derive(Debug)]
+impl<R> Parser<R>
-struct Identifier(String);
-
-#[derive(Debug)]
-pub enum Expression {
-    Declaration {
-        identifier: Identifier,
-        value: Box<Expression>,
-    },
-    Assignment {
-        identifier: Identifier,
-        value: Box<Expression>,
-    },
-    Binary {
-        left: Box<Expression>,
-        operator: Symbol,
-        right: Box<Expression>,
-    },
-    Literal(Literal),
-}
-
-pub struct Parser<T>
 where
-    T: Read + Seek,
+    R: Read + Seek,
 {
-    tokenizer: Tokenizer<T>,
+    pub fn new(tokenizer: Tokenizer<R>) -> Self {
-}
+        Parser {
-
+            tokenizer,
-impl<T> Parser<T>
+            current_token: None,
-where
-    T: Read + Seek,
-{
-    pub fn new(tokenizer: Tokenizer<T>) -> Self {
-        Self { tokenizer }
-    }
-
-    pub fn parse(&mut self) -> Result<Option<Expression>, ParseError> {
-        while let Some(token) = self.tokenizer.next_token()? {
-            match token.token_type {
-                TokenType::Number(n) => {
-                    if let Some(Token {
-                        token_type: TokenType::Symbol(s),
-                        ..
-                    }) = self.tokenizer.peek_next()?
-                    {
-                        if s.is_operator() {
-                            self.tokenizer.next_token()?;
-                            return Ok(Some(Expression::Binary {
-                                left: Box::new(Expression::Literal(Literal::Number(n))),
-                                operator: s,
-                                right: Box::new(self.parse()?.ok_or(ParseError::UnknownError)?),
-                            }));
-                        }
-                    } else {
-                        return Ok(Some(Expression::Literal(Literal::Number(n))));
-                    }
-                }
-                _ => return Err(ParseError::UnexpectedToken { token }),
-            }
         }
-        return Err(ParseError::UnknownError);
     }
 
-    fn parse_declaration(&mut self) -> Result<Expression, ParseError> {
+    pub fn parse(&mut self) -> Result<tree_node::Expression, ParseError> {
-        let identifier = match self.tokenizer.next_token()? {
+        self.current_token = self.tokenizer.next_token()?;
-            Some(token) => match token.token_type {
+        self.expression()
-                TokenType::Identifier(i) => Identifier(i),
+    }
-                _ => return Err(ParseError::UnexpectedToken { token }),
+
-            },
+    fn expression(&mut self) -> Result<tree_node::Expression, ParseError> {
-            None => return Err(ParseError::UnknownError),
+        let current_token = self
+            .current_token
+            .as_ref()
+            .ok_or(ParseError::UnknownError)?;
+
+        Ok(match current_token.token_type {
+            // Match a number or string literal as long as the next token is not an operator
+            TokenType::Number(_) | TokenType::String(_)
+                if !matches!(
+                    self.tokenizer.peek_next()?, Some(Token { token_type: TokenType::Symbol(e), .. }) if e.is_operator()
+                ) =>
+            {
+                Expression::Literal(self.literal()?)
+            }
+
+            // Match a negation operator
+            TokenType::Symbol(Symbol::Minus) => Expression::Negation(Box::new(self.parse()?)),
+
+            _ if matches!(self.tokenizer.peek_next()?, Some(Token { token_type: TokenType::Symbol(e), .. }) if e.is_operator()) => {
+                Expression::BinaryExpression(self.binary()?)
+            }
+
+            // Something went wrong. Return an error
+            _ => {
+                return Err(ParseError::UnexpectedToken {
+                    token: current_token.clone(),
+                })
+            }
+        })
+    }
+
+    fn binary(&mut self) -> Result<tree_node::BinaryExpression, ParseError> {
+        let literal = self.literal()?;
+
+        let Some(Token {
+            token_type: TokenType::Symbol(operator),
+            ..
+        }) = self.current_token
+        else {
+            return Err(ParseError::UnknownError);
+        };
+        self.current_token = self.tokenizer.next_token()?;
+
+        Ok(match operator {
+            Symbol::Plus => BinaryExpression::Add(
+                Box::new(Expression::Literal(literal)),
+                Box::new(self.expression()?),
+            ),
+            Symbol::Asterisk => BinaryExpression::Multiply(
+                Box::new(Expression::Literal(literal)),
+                Box::new(self.expression()?),
+            ),
+            Symbol::Slash => BinaryExpression::Divide(
+                Box::new(Expression::Literal(literal)),
+                Box::new(self.expression()?),
+            ),
+            Symbol::Minus => BinaryExpression::Subtract(
+                Box::new(Expression::Literal(literal)),
+                Box::new(self.expression()?),
+            ),
+            _ => {
+                return Err(ParseError::UnexpectedToken {
+                    token: Token {
+                        token_type: TokenType::Symbol(operator),
+                        line: 0,
+                        column: 0,
+                    },
+                })
+            }
+        })
+    }
+
+    fn literal(&mut self) -> Result<tree_node::Literal, ParseError> {
+        let current_token = self
+            .current_token
+            .as_ref()
+            .ok_or(ParseError::UnknownError)?;
+
+        let to_return = match current_token.token_type {
+            TokenType::Number(ref number) => tree_node::Literal::Number(number.clone()),
+            TokenType::String(ref string) => tree_node::Literal::String(string.clone()),
+            _ => {
+                return Err(ParseError::UnexpectedToken {
+                    token: current_token.clone(),
+                })
+            }
         };
 
-        return Ok(Expression::Declaration {
+        self.current_token = self.tokenizer.next_token()?;
-            identifier,
+        Ok(to_return)
-            value: Box::new(self.parse()?.ok_or(ParseError::UnknownError)?),
-        });
     }
 }
 
 #[cfg(test)]
 mod tests {
+    use super::tree_node::*;
     use super::*;
     use anyhow::Result;
 
     #[test]
-    fn test_parser() -> Result<()> {
+    fn test_add_expr() -> Result<()> {
-        let input = r#"
+        let input = "123 + 456";
-            5.3245 + 5
 
+        let mut parser = Parser::new(Tokenizer::from(input.to_owned()));
 
+        let result = parser.parse()?;
+        let formatted_output = format!("{}", result);
 
+        assert_eq!(formatted_output, "(123 + 456)");
+        Ok(())
+    }
 
-            45 - 2
+    #[test]
-        "#;
+    fn test_parse_number() -> Result<()> {
+        let input = "123";
+        let mut parser = Parser::new(Tokenizer::from(input.to_owned()));
+        let result = parser.parse()?;
 
-        let tokenizer = Tokenizer::from(input.to_owned());
+        let formatted_output = format!("{}", result);
-        let mut parser = Parser::new(tokenizer);
 
-        let expr = parser.parse()?;
+        assert_eq!(formatted_output, "123");
 
-        println!("{:?}", expr);
+        Ok(())
+    }
 
-        let expr = parser.parse()?;
+    #[test]
+    fn test_parse_negation() -> Result<()> {
+        let input = "-123";
+        let mut parser = Parser::new(Tokenizer::from(input.to_owned()));
+        let result = parser.parse()?;
 
-        println!("{:?}", expr);
+        let formatted_output = format!("{}", result);
+
+        assert_eq!(formatted_output, "(-123)");
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_order_of_operations() -> Result<()> {
+        let input = "123 - 456 + 789";
+
+        let mut parser = Parser::new(Tokenizer::from(input.to_owned()));
+        let result = parser.parse()?;
+
+        let formatted_output = format!("{}", result);
+        println!("{}", formatted_output);
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_chained_operators() -> Result<()> {
+        let input = "123 + 456 * 789";
+        let mut parser = Parser::new(Tokenizer::from(input.to_owned()));
+        let result = parser.parse()?;
+
+        let formatted_output = format!("{}", result);
+
+        assert_eq!(formatted_output, "(123 + (456 * 789))");
 
         Ok(())
     }

src/parser/tree_node.rs

@@ -0,0 +1,83 @@
+use crate::tokenizer::token::Number;
+
+#[derive(Debug, Eq, PartialEq)]
+pub enum Literal {
+    Number(Number),
+    String(String),
+}
+
+impl std::fmt::Display for Literal {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Literal::Number(n) => write!(f, "{}", n),
+            Literal::String(s) => write!(f, "{}", s),
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum BinaryExpression {
+    Add(Box<Expression>, Box<Expression>),
+    Multiply(Box<Expression>, Box<Expression>),
+    Divide(Box<Expression>, Box<Expression>),
+    Subtract(Box<Expression>, Box<Expression>),
+}
+
+impl std::fmt::Display for BinaryExpression {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            BinaryExpression::Add(l, r) => write!(f, "({} + {})", l, r),
+            BinaryExpression::Multiply(l, r) => write!(f, "({} * {})", l, r),
+            BinaryExpression::Divide(l, r) => write!(f, "({} / {})", l, r),
+            BinaryExpression::Subtract(l, r) => write!(f, "({} - {})", l, r),
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum LogicalExpression {
+    And(Box<Expression>, Box<Expression>),
+    Or(Box<Expression>, Box<Expression>),
+    Not(Box<Expression>),
+    Equal(Box<Expression>, Box<Expression>),
+    NotEqual(Box<Expression>, Box<Expression>),
+    GreaterThan(Box<Expression>, Box<Expression>),
+    GreaterThanOrEqual(Box<Expression>, Box<Expression>),
+    LessThan(Box<Expression>, Box<Expression>),
+    LessThanOrEqual(Box<Expression>, Box<Expression>),
+}
+
+impl std::fmt::Display for LogicalExpression {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            LogicalExpression::And(l, r) => write!(f, "({} && {})", l, r),
+            LogicalExpression::Or(l, r) => write!(f, "({} || {})", l, r),
+            LogicalExpression::Not(e) => write!(f, "(!{})", e),
+            LogicalExpression::Equal(l, r) => write!(f, "({} == {})", l, r),
+            LogicalExpression::NotEqual(l, r) => write!(f, "({} != {})", l, r),
+            LogicalExpression::GreaterThan(l, r) => write!(f, "({} > {})", l, r),
+            LogicalExpression::GreaterThanOrEqual(l, r) => write!(f, "({} >= {})", l, r),
+            LogicalExpression::LessThan(l, r) => write!(f, "({} < {})", l, r),
+            LogicalExpression::LessThanOrEqual(l, r) => write!(f, "({} <= {})", l, r),
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum Expression {
+    Literal(Literal),
+    Negation(Box<Expression>),
+    BinaryExpression(BinaryExpression),
+    LogicalExpression(LogicalExpression),
+}
+
+impl std::fmt::Display for Expression {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Expression::Literal(l) => write!(f, "{}", l),
+            Expression::Negation(e) => write!(f, "(-{})", e),
+            Expression::BinaryExpression(e) => write!(f, "{}", e),
+            Expression::LogicalExpression(e) => write!(f, "{}", e),
+        }
+    }
+}

src/tokenizer/mod.rs

@@ -1,6 +1,7 @@
 pub mod token;
 
 use std::{
+    collections::VecDeque,
     fs::File,
     io::{BufReader, Cursor, Read, Seek, SeekFrom},
     path::PathBuf,
@@ -123,6 +124,8 @@ where
         Ok(())
     }
 
+    /// Consumes the tokenizer and returns the next token in the stream
+    /// If there are no more tokens in the stream, this function returns None
     pub fn next_token(&mut self) -> Result<Option<Token>, TokenizerError> {
         while let Some(next_char) = self.next_char()? {
             // skip whitespace
@@ -167,6 +170,8 @@ where
         }
     }
 
+    /// Peeks the next token in the stream without consuming it
+    /// If there are no more tokens in the stream, this function returns None
     pub fn peek_next(&mut self) -> Result<Option<Token>, TokenizerError> {
         let current_pos = self.reader.stream_position()?;
         let column = self.column.clone();
@@ -408,6 +413,106 @@ where
     }
 }
 
+pub struct TokenizerBuffer<T>
+where
+    T: Read + Seek,
+{
+    tokenizer: Tokenizer<T>,
+    buffer: VecDeque<Token>,
+    history: VecDeque<Token>,
+}
+
+impl<T> TokenizerBuffer<T>
+where
+    T: Seek + Read,
+{
+    pub fn new(tokenizer: Tokenizer<T>) -> Self {
+        Self {
+            tokenizer,
+            buffer: VecDeque::new(),
+            history: VecDeque::with_capacity(128),
+        }
+    }
+
+    /// Reads the next token from the tokenizer, pushing the value to the back of the history
+    /// and returning the token
+    pub fn next(&mut self) -> Result<Option<Token>, TokenizerError> {
+        if let Some(token) = self.buffer.pop_front() {
+            self.history.push_back(token.clone());
+            return Ok(Some(token));
+        }
+
+        let token = self.tokenizer.next_token()?;
+        if let Some(ref token) = token {
+            self.history.push_back(token.clone());
+        }
+        Ok(token)
+    }
+
+    /// Peeks the next token in the stream without adding to the history stack
+    pub fn peek(&mut self) -> Result<Option<Token>, TokenizerError> {
+        if let Some(token) = self.buffer.front() {
+            return Ok(Some(token.clone()));
+        }
+
+        let token = self.tokenizer.peek_next()?;
+        Ok(token)
+    }
+
+    fn seek_from_start(&mut self, pos: usize) -> Result<(), TokenizerError> {
+        // if pos 
+
+
+        Ok(())
+    }
+
+    fn seek_from_current(&mut self, seek_to: i64) -> Result<(), TokenizerError> {
+        // if seek_to > 0 then we need to check if the buffer has enough tokens to pop, otherwise we need to read from the tokenizer
+        // if seek_to < 0 then we need to pop from the history and push to the front of the buffer. If not enough, then we throw (we reached the front of the history)
+        // if seek_to == 0 then we don't need to do anything
+
+        if seek_to > 0 {
+            let mut tokens = Vec::with_capacity(seek_to as usize);
+            for _ in 0..seek_to {
+                if let Some(token) = self.tokenizer.next_token()? {
+                    tokens.push(token);
+                } else {
+                    return Err(TokenizerError::IOError(std::io::Error::new(
+                        std::io::ErrorKind::UnexpectedEof,
+                        "Unexpected EOF",
+                    )));
+                }
+            }
+            self.history.extend(tokens);
+        } else if seek_to < 0 {
+            let seek_to = seek_to.abs() as usize;
+            let mut tokens = Vec::with_capacity(seek_to);
+            for _ in 0..seek_to {
+                if let Some(token) = self.history.pop_back() {
+                    tokens.push(token);
+                } else {
+                    return Err(TokenizerError::IOError(std::io::Error::new(
+                        std::io::ErrorKind::UnexpectedEof,
+                        "Unexpected EOF",
+                    )));
+                }
+            }
+            self.buffer.extend(tokens.into_iter().rev());
+        }
+
+        Ok(())
+    }
+
+    /// Adds to or removes from the History stack, allowing the user to move back and forth in the stream
+    pub fn seek(&mut self, from: SeekFrom) -> Result<(), TokenizerError> {
+        Ok(match from {
+            SeekFrom::Start(pos) => self.seek_from_start(pos as usize)?,
+            SeekFrom::Current(seek_to) => self.seek_from_current(seek_to)?,
+            SeekFrom::End(_) => unimplemented!("SeekFrom::End will not be implemented"),
+        })
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -422,6 +527,35 @@ mod tests {
         }
     "#;
 
+    #[test]
+    fn test_tokenizer_buffer_seek_from_start() -> Result<()> {
+        let tokenizer = Tokenizer::from(TEST_STRING.to_owned());
+        let mut buffer = TokenizerBuffer::new(tokenizer);
+
+        let token = buffer.next()?;
+        assert_eq!(token.unwrap().token_type, TokenType::Keyword(Keyword::Fn));
+
+        let token = buffer.next()?;
+        assert_eq!(
+            token.unwrap().token_type,
+            TokenType::Identifier(String::from("test"))
+        );
+
+        buffer.seek(SeekFrom::Start(0))?;
+
+        let token = buffer.next()?;
+
+        assert_eq!(token.unwrap().token_type, TokenType::Keyword(Keyword::Fn));
+
+        buffer.seek(SeekFrom::Start(16))?;
+
+        let token = buffer.next()?;
+
+        assert_eq!(token.unwrap().token_type, TokenType::Keyword(Keyword::Let));
+
+        Ok(())
+    }
+
     #[test]
     fn test_tokenizer_from_path_ok() {
         let tokenizer = Tokenizer::from_path(TEST_FILE);

src/tokenizer/token.rs

@@ -1,4 +1,4 @@
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Clone)]
 pub struct Token {
     /// The type of the token
     pub token_type: TokenType,
@@ -18,7 +18,7 @@ impl Token {
     }
 }
 
-#[derive(Debug, PartialEq, Hash, Eq)]
+#[derive(Debug, PartialEq, Hash, Eq, Clone)]
 pub enum TokenType {
     /// Represents a string token
     String(String),
@@ -50,7 +50,7 @@ impl std::fmt::Display for TokenType {
     }
 }
 
-#[derive(Debug, PartialEq, Hash, Eq)]
+#[derive(Debug, PartialEq, Hash, Eq, Clone, Copy)]
 pub enum Number {
     /// Represents an integer number
     Integer(u64),
@@ -67,7 +67,7 @@ impl std::fmt::Display for Number {
     }
 }
 
-#[derive(Debug, PartialEq, Hash, Eq)]
+#[derive(Debug, PartialEq, Hash, Eq, Clone, Copy)]
 pub enum Symbol {
     // Single Character Symbols
     /// Represents the `(` symbol
@@ -157,7 +157,7 @@ impl Symbol {
     }
 }
 
-#[derive(Debug, PartialEq, Hash, Eq)]
+#[derive(Debug, PartialEq, Hash, Eq, Clone, Copy)]
 pub enum Keyword {
     /// Represents the `let` keyword
     Let,