Add mutability parsing

reid/examples/mutable.rs

@@ -1,9 +1,9 @@
 use reid::compile;
 
-pub static ARITHMETIC: &str = include_str!("./reid/arithmetic.reid");
+pub static MUTABLE: &str = include_str!("./reid/mutable.reid");
 
 fn main() {
-    let text = match compile(ARITHMETIC) {
+    let text = match compile(MUTABLE) {
         Ok(t) => t,
         Err(e) => panic!("{}", e),
     };

reid/examples/reid/arithmetic.reid

@@ -1,13 +0,0 @@
-// Arithmetic, function calls and imports!
-
-fn main() {
-    let test = 9;
-    let simpleAdd = 2 + 2;
-    let simpleSub = 7 - 2; // 14
-    
-    if simpleAdd < test {
-        return 3;
-    }
-
-    return arithmetic + simpleSub + boop;
-}

reid/examples/reid/mutable.reid

@@ -0,0 +1,15 @@
+// Arithmetic, function calls and imports!
+
+fn indirection() -> bool {
+    return true;
+}
+
+fn main() -> u16 {
+    let mut test = 5;
+
+    if indirection() {
+        test = 11;
+    }
+
+    return test;
+}

reid/src/ast/mod.rs

@@ -92,7 +92,14 @@ pub struct IfExpression(
 );
 
 #[derive(Debug, Clone)]
-pub struct LetStatement(pub String, pub Option<Type>, pub Expression, pub TokenRange);
+pub struct LetStatement(
+    pub String,
+    pub Option<Type>,
+    /// Mutability
+    pub bool,
+    pub Expression,
+    pub TokenRange,
+);
 
 #[derive(Debug, Clone)]
 pub struct ImportStatement(pub Vec<String>, pub TokenRange);
@@ -125,7 +132,11 @@ pub struct Block(
 #[derive(Debug, Clone)]
 pub enum BlockLevelStatement {
     Let(LetStatement),
-    Import { _i: ImportStatement },
+    /// Try to set a variable to a specified expression value
+    Set(String, Expression),
+    Import {
+        _i: ImportStatement,
+    },
     Expression(Expression),
     Return(ReturnType, Expression),
 }

reid/src/ast/parse.rs

@@ -223,6 +223,7 @@ impl Parse for IfExpression {
 impl Parse for LetStatement {
     fn parse(mut stream: TokenStream) -> Result<LetStatement, Error> {
         stream.expect(Token::LetKeyword)?;
+        let mutability = stream.expect(Token::MutKeyword).is_ok();
 
         if let Some(Token::Identifier(variable)) = stream.next() {
             stream.expect(Token::Equals)?;
@@ -232,6 +233,7 @@ impl Parse for LetStatement {
             Ok(LetStatement(
                 variable,
                 None, // TODO add possibility to name type
+                mutability,
                 expression,
                 stream.get_range().unwrap(),
             ))
@@ -361,6 +363,9 @@ impl Parse for BlockLevelStatement {
                 Stmt::Return(ReturnType::Hard, exp)
             }
             _ => {
+                if let Ok(SetStatement(ident, expr)) = stream.parse() {
+                    Stmt::Set(ident, expr)
+                } else {
                     if let Ok(e) = stream.parse() {
                         if stream.expect(Token::Semi).is_ok() {
                             Stmt::Expression(e)
@@ -371,10 +376,27 @@ impl Parse for BlockLevelStatement {
                         Err(stream.expected_err("expression")?)?
                     }
                 }
+            }
         })
     }
 }
 
+#[derive(Debug)]
+pub struct SetStatement(String, Expression);
+
+impl Parse for SetStatement {
+    fn parse(mut stream: TokenStream) -> Result<Self, Error> {
+        if let Some(Token::Identifier(ident)) = stream.next() {
+            stream.expect(Token::Equals)?;
+            let expr = stream.parse()?;
+            stream.expect(Token::Semi)?;
+            Ok(Self(ident, expr))
+        } else {
+            Err(stream.expected_err("identifier")?)?
+        }
+    }
+}
+
 impl Parse for TopLevelStatement {
     fn parse(mut stream: TokenStream) -> Result<Self, Error> {
         use TopLevelStatement as Stmt;

reid/src/ast/process.rs

@@ -68,12 +68,13 @@ impl ast::Block {
                                 .map(|t| t.0.into())
                                 .unwrap_or(mir::TypeKind::Vague(mir::VagueType::Unknown)),
                             s_let.0.clone(),
-                            s_let.3.into(),
+                            s_let.4.into(),
                         ),
-                        s_let.2.process(),
+                        s_let.3.process(),
                     ),
-                    s_let.3,
+                    s_let.4,
                 ),
+                ast::BlockLevelStatement::Set(_, expression) => todo!(),
                 ast::BlockLevelStatement::Import { _i } => todo!(),
                 ast::BlockLevelStatement::Expression(e) => (StmtKind::Expression(e.process()), e.1),
                 ast::BlockLevelStatement::Return(_, e) => (StmtKind::Expression(e.process()), e.1),

reid/src/lexer.rs

@@ -12,6 +12,8 @@ pub enum Token {
     // Keywords
     /// `let`
     LetKeyword,
+    /// `mut`
+    MutKeyword,
     /// `import`
     ImportKeyword,
     /// `return`
@@ -170,6 +172,7 @@ pub fn tokenize<T: Into<String>>(to_tokenize: T) -> Result<Vec<FullToken>, Error
                 // Check for keywords
                 let variant = match value.as_str() {
                     "let" => Token::LetKeyword,
+                    "mut" => Token::MutKeyword,
                     "import" => Token::ImportKeyword,
                     "return" => Token::ReturnKeyword,
                     "fn" => Token::FnKeyword,