Change eval compile to statement

README.md

@@ -12,6 +12,13 @@ To test RustPython, do the following:
     $ cargo run demo.py
     42
 
+Or use the interactive shell:
+
+    $ cargo run
+    Welcome to rustpython
+    >>>>> 2+2
+    4
+
 Or use pip to install extra modules:
 
     $ cargo run -m pip install requests

parser/src/lexer.rs

@@ -157,7 +157,7 @@ impl<'input> Lexer<'input> {
 
     fn is_char(&self) -> bool {
         match self.chr0 {
-            Some('a'...'z') => return true,
+            Some('a'...'z') | Some('A'...'Z') => return true,
             _ => return false,
         }
     }
@@ -226,8 +226,7 @@ impl<'input> Lexer<'input> {
 
             match self.chr0 {
                 Some('0'...'9') => return Some(self.lex_number()),
-                // TODO: 'A'...'Z'
-                Some('a'...'z') => return Some(self.lex_identifier()),
+                Some('a'...'z') | Some('A'...'Z') => return Some(self.lex_identifier()),
                 Some('#') => {
                     self.lex_comment();
                     continue;
@@ -370,6 +369,17 @@ impl<'input> Lexer<'input> {
                         _ => return Some(Ok((tok_start, Tok::At, self.location + 1))),
                     }
                 }
+                Some('!') => {
+                    let tok_start = self.location;
+                    self.next_char();
+                    match self.chr0 {
+                        Some('=') => {
+                            self.next_char();
+                            return Some(Ok((tok_start, Tok::NotEqual, self.location + 1)));
+                        },
+                        _ => panic!("Invalid token '!'"),
+                    }
+                }
                 Some('~') => {
                     self.next_char();
                     return Some(Ok((0, Tok::Tilde, 0)));

parser/src/parser.rs

@@ -46,6 +46,14 @@ pub fn parse_program(source: &String) -> Result<ast::Program, String> {
     }
 }
 
+pub fn parse_statement(source: &String) -> Result<ast::Statement, String> {
+    let lxr = lexer::Lexer::new(&source);
+    match python::StatementParser::new().parse(lxr) {
+        Err(why) => Err(String::from(format!("{:?}", why))),
+        Ok(p) => Ok(p),
+    }
+}
+
 pub fn parse_expression(source: &String) -> Result<ast::Expression, String> {
     let lxr = lexer::Lexer::new(&source);
     match python::ExpressionParser::new().parse(lxr) {
@@ -56,7 +64,7 @@ pub fn parse_expression(source: &String) -> Result<ast::Expression, String> {
 
 #[cfg(test)]
 mod tests {
-    use super::parse_source;
+    use super::parse_program;
     use super::ast;
 
     #[test]
@@ -87,7 +95,7 @@ mod tests {
     #[test]
     fn test_parse_print_2() {
         let source = String::from("print('Hello world', 2)\n");
-        let parse_ast = parse_source(&source).unwrap();
+        let parse_ast = parse_program(&source).unwrap();
         assert_eq!(
             parse_ast,
             ast::Program {

parser/src/python.lalrpop

@@ -20,7 +20,7 @@ Suite: Vec<ast::Statement> = {
   "\n" indent <s:Statement+> dedent => s,
 };
 
-Statement: ast::Statement = {
+pub Statement: ast::Statement = {
   SimpleStatement,
   CompoundStatement,
 };

src/main.rs

@@ -66,7 +66,7 @@ fn run_shell() {
         print!(">>>>> ");  // Use 5 items. pypy has 4, cpython has 3.
         io::stdout().flush().ok().expect("Could not flush stdout");
         io::stdin().read_line(&mut input);
-        input = input.trim().to_string();
+        // input = input.trim().to_string();
         debug!("You entered {:?}", input);
         let result = eval(&mut vm, &input);
         match result {

vm/src/compile.rs

@@ -26,9 +26,17 @@ pub fn compile(source: &String, mode: Mode) -> Result<CodeObject, String> {
             }
         }
         Mode::Eval => {
-            match parser::parse_expression(source) {
-                Ok(ast) => {
-                    compiler.compile_expression(ast);
+            match parser::parse_statement(source) {
+                Ok(statement) => {
+                    let need_none = if let &ast::Statement::Expression { expression: _ } = &statement {
+                        false
+                    } else {
+                        true
+                    };
+                    compiler.compile_statement(statement);
+                    if need_none {
+                        compiler.emit(Instruction::LoadConst { value: bytecode::Constant::None });
+                    }
                     compiler.emit(Instruction::ReturnValue);
                     Ok(compiler.pop_code_object())
                 }
@@ -90,7 +98,8 @@ impl Compiler {
                 self.compile_expression(expression);
 
                 // Pop result of stack, since we not use it:
-                self.emit(Instruction::Pop);
+                // TODO: do we need to clean the stack here?
+                // self.emit(Instruction::Pop);
             }
             ast::Statement::If { test, body } => {
                 self.compile_expression(test);

vm/src/vm.rs

@@ -295,7 +295,7 @@ impl VirtualMachine {
     fn _eq(&mut self, a: PyObjectRef, b: PyObjectRef) -> PyResult {
         let b2 = &*b.borrow();
         let a2 = &*a.borrow();
-        let result_bool = a == b;
+        let result_bool = a2 == b2;
         let result = self.ctx.new_bool(result_bool);
         Ok(result)
     }
@@ -303,7 +303,7 @@ impl VirtualMachine {
     fn _ne(&mut self, a: PyObjectRef, b: PyObjectRef) -> PyResult {
         let b2 = &*b.borrow();
         let a2 = &*a.borrow();
-        let result_bool = a != b;
+        let result_bool = a2 != b2;
         let result = self.ctx.new_bool(result_bool);
         Ok(result)
     }