Add lexing and parsing for I/O built-in functions; Refactor built-in function parsing

dust-lang/src/built_in_function.rs

@@ -1,4 +1,7 @@
-use std::fmt::{self, Display, Formatter};
+use std::{
+    fmt::{self, Display, Formatter},
+    io::{self, stdin},
+};
 
 use serde::{Deserialize, Serialize};
 
@@ -6,9 +9,16 @@ use crate::{Type, Value};
 
 #[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
 pub enum BuiltInFunction {
+    // Integer and float tools
     IsEven,
     IsOdd,
+
+    // List tools
     Length,
+
+    // I/O
+    ReadLine,
+    WriteLine,
 }
 
 impl BuiltInFunction {
@@ -17,6 +27,8 @@ impl BuiltInFunction {
             BuiltInFunction::IsEven => "is_even",
             BuiltInFunction::IsOdd => "is_odd",
             BuiltInFunction::Length => "length",
+            BuiltInFunction::ReadLine => "read_line",
+            BuiltInFunction::WriteLine => "write_line",
         }
     }
 
@@ -24,13 +36,13 @@ impl BuiltInFunction {
         &self,
         _type_arguments: Option<Vec<Type>>,
         value_arguments: Option<Vec<Value>>,
-    ) -> Result<Value, BuiltInFunctionError> {
+    ) -> Result<Option<Value>, BuiltInFunctionError> {
         match self {
             BuiltInFunction::IsEven => {
                 if let Some(value_arguments) = value_arguments {
                     if value_arguments.len() == 1 {
                         if let Some(integer) = value_arguments[0].as_integer() {
-                            Ok(Value::boolean(integer % 2 == 0))
+                            Ok(Some(Value::boolean(integer % 2 == 0)))
                         } else {
                             Err(BuiltInFunctionError::ExpectedInteger)
                         }
@@ -45,7 +57,7 @@ impl BuiltInFunction {
                 if let Some(value_arguments) = value_arguments {
                     if value_arguments.len() == 1 {
                         if let Some(integer) = value_arguments[0].as_integer() {
-                            Ok(Value::boolean(integer % 2 != 0))
+                            Ok(Some(Value::boolean(integer % 2 != 0)))
                         } else {
                             Err(BuiltInFunctionError::ExpectedInteger)
                         }
@@ -60,7 +72,7 @@ impl BuiltInFunction {
                 if let Some(value_arguments) = value_arguments {
                     if value_arguments.len() == 1 {
                         if let Some(list) = value_arguments[0].as_list() {
-                            Ok(Value::integer(list.len() as i64))
+                            Ok(Some(Value::integer(list.len() as i64)))
                         } else {
                             Err(BuiltInFunctionError::ExpectedInteger)
                         }
@@ -71,6 +83,30 @@ impl BuiltInFunction {
                     Err(BuiltInFunctionError::WrongNumberOfValueArguments)
                 }
             }
+            BuiltInFunction::ReadLine => {
+                if value_arguments.is_none() {
+                    let mut input = String::new();
+
+                    stdin().read_line(&mut input)?;
+
+                    Ok(Some(Value::string(input)))
+                } else {
+                    Err(BuiltInFunctionError::WrongNumberOfValueArguments)
+                }
+            }
+            BuiltInFunction::WriteLine => {
+                if let Some(value_arguments) = value_arguments {
+                    if value_arguments.len() == 1 {
+                        println!("{}", value_arguments[0]);
+
+                        Ok(None)
+                    } else {
+                        Err(BuiltInFunctionError::WrongNumberOfValueArguments)
+                    }
+                } else {
+                    Err(BuiltInFunctionError::WrongNumberOfValueArguments)
+                }
+            }
         }
     }
 
@@ -79,6 +115,8 @@ impl BuiltInFunction {
             BuiltInFunction::IsEven => Some(Type::Boolean),
             BuiltInFunction::IsOdd => Some(Type::Boolean),
             BuiltInFunction::Length => Some(Type::Integer),
+            BuiltInFunction::ReadLine => Some(Type::String),
+            BuiltInFunction::WriteLine => None,
         }
     }
 }
@@ -92,5 +130,12 @@ impl Display for BuiltInFunction {
 #[derive(Debug, Clone, PartialEq)]
 pub enum BuiltInFunctionError {
     ExpectedInteger,
+    Io(io::ErrorKind),
     WrongNumberOfValueArguments,
 }
+
+impl From<io::Error> for BuiltInFunctionError {
+    fn from(error: io::Error) -> Self {
+        Self::Io(error.kind())
+    }
+}

dust-lang/src/lex.rs

@@ -250,6 +250,8 @@ impl<'a> Lexer<'a> {
             "is_even" => Token::IsEven,
             "is_odd" => Token::IsOdd,
             "length" => Token::Length,
+            "read_line" => Token::ReadLine,
+            "write_line" => Token::WriteLine,
             _ => Token::Identifier(Identifier::new(string)),
         };
 

dust-lang/src/parse.rs

@@ -258,7 +258,19 @@ impl<'src> Parser<'src> {
                     }
                 }
             }
-            (Token::IsEven, left_span) => {
+            (
+                Token::IsEven | Token::IsOdd | Token::Length | Token::ReadLine | Token::WriteLine,
+                left_span,
+            ) => {
+                let function = match self.current.0 {
+                    Token::IsEven => BuiltInFunction::IsEven,
+                    Token::IsOdd => BuiltInFunction::IsOdd,
+                    Token::Length => BuiltInFunction::Length,
+                    Token::ReadLine => BuiltInFunction::ReadLine,
+                    Token::WriteLine => BuiltInFunction::WriteLine,
+                    _ => unreachable!(),
+                };
+
                 self.next_token()?;
 
                 if let (Token::LeftParenthesis, _) = self.current {
@@ -270,80 +282,38 @@ impl<'src> Parser<'src> {
                     });
                 }
 
-                if let (Token::RightParenthesis, _) = self.current {
+                let mut value_arguments: Option<Vec<Node>> = None;
-                    self.next_token()?;
+
-                } else {
+                loop {
-                    return Err(ParseError::ExpectedClosingParenthesis {
+                    if let (Token::RightParenthesis, _) = self.current {
-                        actual: self.current.0.clone(),
+                        self.next_token()?;
-                        span: self.current.1,
+                        break;
-                    });
+                    }
+
+                    if let (Token::Comma, _) = self.current {
+                        self.next_token()?;
+                        continue;
+                    }
+
+                    if let Ok(node) = self.parse_node(0) {
+                        if let Some(ref mut arguments) = value_arguments {
+                            arguments.push(node);
+                        } else {
+                            value_arguments = Some(vec![node]);
+                        }
+                    } else {
+                        return Err(ParseError::ExpectedClosingParenthesis {
+                            actual: self.current.0.clone(),
+                            span: self.current.1,
+                        });
+                    }
                 }
 
                 Ok(Node::new(
                     Statement::BuiltInFunctionCall {
-                        function: BuiltInFunction::IsEven,
+                        function,
                         type_arguments: None,
-                        value_arguments: None,
+                        value_arguments,
-                    },
-                    left_span,
-                ))
-            }
-            (Token::IsOdd, left_span) => {
-                self.next_token()?;
-
-                if let (Token::LeftParenthesis, _) = self.current {
-                    self.next_token()?;
-                } else {
-                    return Err(ParseError::ExpectedOpeningParenthesis {
-                        actual: self.current.0.clone(),
-                        span: self.current.1,
-                    });
-                }
-
-                if let (Token::RightParenthesis, _) = self.current {
-                    self.next_token()?;
-                } else {
-                    return Err(ParseError::ExpectedClosingParenthesis {
-                        actual: self.current.0.clone(),
-                        span: self.current.1,
-                    });
-                }
-
-                Ok(Node::new(
-                    Statement::BuiltInFunctionCall {
-                        function: BuiltInFunction::IsOdd,
-                        type_arguments: None,
-                        value_arguments: None,
-                    },
-                    left_span,
-                ))
-            }
-            (Token::Length, left_span) => {
-                self.next_token()?;
-
-                if let (Token::LeftParenthesis, _) = self.current {
-                    self.next_token()?;
-                } else {
-                    return Err(ParseError::ExpectedOpeningParenthesis {
-                        actual: self.current.0.clone(),
-                        span: self.current.1,
-                    });
-                }
-
-                if let (Token::RightParenthesis, _) = self.current {
-                    self.next_token()?;
-                } else {
-                    return Err(ParseError::ExpectedClosingParenthesis {
-                        actual: self.current.0.clone(),
-                        span: self.current.1,
-                    });
-                }
-
-                Ok(Node::new(
-                    Statement::BuiltInFunctionCall {
-                        function: BuiltInFunction::Length,
-                        type_arguments: None,
-                        value_arguments: None,
                     },
                     left_span,
                 ))

dust-lang/src/token.rs

@@ -20,17 +20,19 @@ pub enum Token {
     IsEven,
     IsOdd,
     Length,
+    ReadLine,
+    WriteLine,
 
     // Symbols
     Comma,
     Dot,
     Equal,
-    Plus,
-    Star,
     LeftParenthesis,
-    RightParenthesis,
     LeftSquareBrace,
+    Plus,
+    RightParenthesis,
     RightSquareBrace,
+    Star,
 }
 
 impl Display for Token {
@@ -45,6 +47,8 @@ impl Display for Token {
             Token::IsEven => write!(f, "is_even"),
             Token::IsOdd => write!(f, "is_odd"),
             Token::Length => write!(f, "length"),
+            Token::ReadLine => write!(f, "read_line"),
+            Token::WriteLine => write!(f, "write_line"),
             Token::Comma => write!(f, ","),
             Token::Dot => write!(f, "."),
             Token::Equal => write!(f, "="),

dust-lang/src/value.rs

@@ -527,18 +527,6 @@ impl ValueInner {
     }
 }
 
-pub trait ValueProperties<'a> {}
-
-pub struct IntegerProperties<'a>(&'a Value);
-
-impl<'a> IntegerProperties<'a> {
-    pub fn is_even(&self) -> bool {
-        self.0.as_integer().unwrap() % 2 == 0
-    }
-}
-
-impl<'a> ValueProperties<'a> for IntegerProperties<'a> {}
-
 impl Eq for ValueInner {}
 
 impl PartialOrd for ValueInner {

dust-lang/src/vm.rs

@@ -114,7 +114,7 @@ impl Vm {
                 };
                 let function_call_return = function.call(None, values)?;
 
-                Ok(Some(function_call_return))
+                Ok(function_call_return)
             }
             Statement::Constant(value) => Ok(Some(value.clone())),
             Statement::FunctionCall {
@@ -226,7 +226,7 @@ impl Vm {
 
                     let function_call_return = function.call(None, Some(value_arguments))?;
 
-                    return Ok(Some(function_call_return));
+                    return Ok(function_call_return);
                 }
 
                 Err(VmError::ExpectedIdentifierOrInteger {