Start implementing binary expressions

src/parser/mod.rs

@@ -1,13 +1,10 @@
 mod tree_node;
 
 use crate::tokenizer::{
-    token::{self, Keyword, Symbol, Token, TokenType},
+    token::{Keyword, Symbol, Token, TokenType},
     Tokenizer, TokenizerBuffer, TokenizerError,
 };
-use std::{
-    collections::HashSet,
-    io::{Read, Seek},
-};
+use std::collections::HashSet;
 use thiserror::Error;
 use tree_node::*;
 
@@ -19,6 +16,8 @@ pub enum ParseError {
     UnexpectedToken { token: Token },
     #[error("Duplicated Identifer\n\nLine: {0}, Column: {1}\nToken: {2}\n", token.line, token.column, token.token_type)]
     DuplicateIdentifier { token: Token },
+    #[error("Invalid Syntax\n\nLine: {0}, Column: {1}\nReason: {reason}", token.line, token.column)]
+    InvalidSyntax { token: Token, reason: String },
     #[error("Unexpected EOF")]
     UnexpectedEOF,
     #[error("An unknown error has occurred")]
@@ -103,6 +102,20 @@ impl Parser {
         }
     }
 
+    /// Parses all the input from the tokenizer buffer and returns the resulting expression
+    /// Expressions are returned in a root block expression node
+    pub fn parse_all(&mut self) -> Result<Option<tree_node::Expression>, ParseError> {
+        let mut expressions = Vec::<Expression>::new();
+
+        while let Some(expression) = self.parse()? {
+            expressions.push(expression);
+        }
+
+        Ok(Some(Expression::BlockExpression(BlockExpression(
+            expressions,
+        ))))
+    }
+
     /// Parses the input from the tokenizer buffer and returns the resulting expression
     pub fn parse(&mut self) -> Result<Option<tree_node::Expression>, ParseError> {
         self.assign_next()?;
@@ -115,6 +128,7 @@ impl Parser {
         Ok(())
     }
 
+    /// Calls `assign_next` and returns the next token in the tokenizer buffer
     fn get_next(&mut self) -> Result<Option<&Token>, ParseError> {
         self.assign_next()?;
         Ok(self.current_token.as_ref())
@@ -125,6 +139,10 @@ impl Parser {
             return Ok(None);
         };
 
+        if token_matches!(current_token, TokenType::EOF) {
+            return Ok(None);
+        }
+
         let to_return = Some(match current_token.token_type {
             // match declarations with a `let` keyword
             TokenType::Keyword(Keyword::Let) => self.declaration()?,
@@ -132,6 +150,14 @@ impl Parser {
             // match functions with a `fn` keyword
             TokenType::Keyword(Keyword::Fn) => Expression::FunctionExpression(self.function()?),
 
+            // match a variable expression with opening parenthesis
+            TokenType::Identifier(_)
+                if self_matches_peek!(self, TokenType::Symbol(Symbol::LParen)) =>
+            {
+                Expression::InvocationExpression(self.invocation()?)
+            }
+
+            // match variable expressions with an identifier
             TokenType::Identifier(ref id) => Expression::Variable(id.clone()),
 
             // match block expressions with a `{` symbol
@@ -139,7 +165,7 @@ impl Parser {
 
             // match literal expressions with a semi-colon afterwards
             TokenType::Number(_) | TokenType::String(_)
-                if self_matches_peek!(self, TokenType::Symbol(Symbol::Semicolon)) =>
+                if !self_matches_peek!(self, TokenType::Symbol(s) if s.is_operator() || s.is_comparison() || s.is_logical()) =>
             {
                 Expression::Literal(self.literal()?)
             }
@@ -154,6 +180,68 @@ impl Parser {
         Ok(to_return)
     }
 
+    fn binary(&mut self) -> Result<BinaryExpression, ParseError> {
+        todo!()
+    }
+
+    fn invocation(&mut self) -> Result<InvocationExpression, ParseError> {
+        let identifier = extract_token_data!(
+            token_from_option!(self.current_token),
+            TokenType::Identifier(ref id),
+            id.clone()
+        );
+
+        // Ensure the next token is a left parenthesis
+        let current_token = token_from_option!(self.get_next()?);
+        if !token_matches!(current_token, TokenType::Symbol(Symbol::LParen)) {
+            return Err(ParseError::UnexpectedToken {
+                token: current_token.clone(),
+            });
+        }
+
+        let mut arguments = Vec::<Expression>::new();
+        // We need to make sure the expressions are NOT BlockExpressions, as they are not allowed
+
+        while !token_matches!(
+            token_from_option!(self.get_next()?),
+            TokenType::Symbol(Symbol::RParen)
+        ) {
+            let current_token = token_from_option!(self.current_token);
+            let expression = self.expression()?.ok_or(ParseError::UnexpectedEOF)?;
+
+            if let Expression::BlockExpression(_) = expression {
+                return Err(ParseError::InvalidSyntax {
+                    token: current_token,
+                    reason: "Block expressions are not allowed in function invocations".to_owned(),
+                });
+            }
+
+            arguments.push(expression);
+
+            // make sure the next token is a comma or right parenthesis
+            if !self_matches_peek!(self, TokenType::Symbol(Symbol::Comma))
+                && !self_matches_peek!(self, TokenType::Symbol(Symbol::RParen))
+            {
+                return Err(ParseError::UnexpectedToken {
+                    token: token_from_option!(self.get_next()?).clone(),
+                });
+            }
+
+            // edge case: if the next token is not a right parenthesis, increment the current token
+            //
+            // This will allow the loop to break on a right parenthesis with the next iteration
+            // which is incremented by the loop
+            if !self_matches_peek!(self, TokenType::Symbol(Symbol::RParen)) {
+                self.assign_next()?;
+            }
+        }
+
+        Ok(InvocationExpression {
+            name: identifier,
+            arguments,
+        })
+    }
+
     fn block(&mut self) -> Result<BlockExpression, ParseError> {
         let mut expressions = Vec::<Expression>::new();
         let current_token = token_from_option!(self.current_token);
@@ -251,7 +339,7 @@ impl Parser {
             });
         }
 
-        let mut arguments = HashSet::<String>::new();
+        let mut arguments = Vec::<String>::new();
 
         // iterate through the arguments. While expression while increment the current token
         // with the `token_from_option!(self.get_next()?)` macro
@@ -269,7 +357,7 @@ impl Parser {
                 });
             }
 
-            arguments.insert(argument);
+            arguments.push(argument);
 
             // make sure the next token is a comma or right parenthesis
             if !self_matches_peek!(self, TokenType::Symbol(Symbol::Comma))
@@ -362,10 +450,26 @@ mod tests {
         let expression = parser.parse()?.unwrap();
 
         assert_eq!(
-            "(fn add(x, y) { { (let z = 5); } })",
+            "(fn add(x, y) { { (let z = x); } })",
             expression.to_string()
         );
 
         Ok(())
     }
+
+    #[test]
+    fn test_function_invocation() -> Result<()> {
+        let input = r#"
+                add();
+            "#;
+
+        let tokenizer = Tokenizer::from(input.to_owned());
+        let mut parser = Parser::new(tokenizer);
+
+        let expression = parser.parse()?.unwrap();
+
+        assert_eq!("add()", expression.to_string());
+
+        Ok(())
+    }
 }