Merge pull request #167 from kyleect/base-class

Implement a base class of `Object`

README.md

@@ -334,6 +334,8 @@ With the syntax and implementation changes so far the Locks language has divered
   - Change `print` from a statement to a function: `print`, `println`
   - Add [`typeof`](https://kyleect.github.io/locks/#/docs#typeof) native function to return a value's type as string
   - Add [`instanceof`](https://kyleect.github.io/locks/#/docs#instanceof) native function to return `boolean` if the value is an instance of the class or super class.
+  - Add the base class [`Object`](https://kyleect.github.io/locks/#/docs#classes-object) class that all classes extend from.
+  - The file `res/lib/locks.locks` is loaded by the VM before running user code. This is where the base class `Object` is defined.
 - Bug Fixes
   - Add `#[repr(C)]` to `ObjectNative`. This fixes a segfault that occurred when there were multiple entries in the `Native` enum.
   - [Remove an OP transformation the compiler](https://github.com/kyleect/locks/pull/135/files#diff-23c5734d7de815d5e64ad2291873d96e9f686a8b11d76481f3d02c905c53341dL403) was doing that would cause a segfault when bound methods were passed to functions e.g. `function(instance.method)`

playground/src/pages/docs.tsx

@@ -486,7 +486,24 @@ const Docs: React.FC = () => (
             'println(greeter.greet("World")); // out: Hello World!!!',
           ]}
           height="425px"
-        />
+        >
+          Classes can extend other classes. All classes extend or decend from
+          the base class `Object`.
+        </DocCard>
+
+        <DocCard
+          title="Object Base Class"
+          anchor="classes-object"
+          code={[
+            'class Example {}',
+            'let example = Example();',
+            'println(instanceof(example, Example)); // out: true',
+            'println(instanceof(example, Object)); // out: true',
+          ]}
+          height="100px"
+        >
+          All classes extend or descend from the base class `Object`.
+        </DocCard>
 
         <DocCard
           title="Class Field/Method Index Access"

res/examples/field/index_access_get_nested.locks

@@ -1,4 +1,4 @@
-class Object {
+class Container {
   let box;
 
   fn init(value) {
@@ -18,6 +18,6 @@ class Box {
   }
 }
 
-let obj = Object(123);
+let container = Container(123);
 
-println(obj["box"]["get"]()); // out: 123
+println(container["box"]["get"]()); // out: 123

res/examples/field/index_access_get_undefined.locks

@@ -1,6 +1,6 @@
-class Object {
+class Test {
 }
 
-let obj = Object();
+let test = Test();
 
-println(obj["key"]); // out: AttributeError: "Object" object has no attribute "key"
+println(test["key"]); // out: AttributeError: "Test" object has no attribute "key"

res/examples/field/index_access_set_undefined.locks

@@ -1,6 +1,6 @@
-class Object {
+class Test {
 }
 
-let obj = Object();
+let test = Test();
 
-obj["key"] = "new value"; // out: AttributeError: "Object" object has no attribute "key"
+test["key"] = "new value"; // out: AttributeError: "Test" object has no attribute "key"

res/examples/instanceof/instance_of_super_class.locks

@@ -15,3 +15,4 @@ println(instanceof(instance, Child)); // out: true
 println(instanceof(instance, Parent)); // out: true
 println(instanceof(instance, GrandParent)); // out: true
 println(instanceof(instance, OtherChild)); // out: false
+println(instanceof(instance, Object)); // out: true

res/examples/variable/local_from_method.locks

@@ -1,6 +1,8 @@
 let foo = "variable";
 
-class Foo {
+class A {}
+
+class Foo extends A {
   fn method() {
     println(foo);
   }

res/lib/locks.locks

@@ -0,0 +1,3 @@
+class Object {
+
+}

src/cmd.rs

@@ -35,8 +35,8 @@ impl Cmd {
             Cmd::Run { path } => {
                 let source = fs::read_to_string(path)
                     .with_context(|| format!("could not read file: {path}"))?;
-                let mut vm = VM::default();
                 let stdout = &mut io::stdout().lock();
+                let mut vm = VM::new();
                 if let Err(e) = vm.run(&source, stdout) {
                     report_err(&source, e);
                     bail!("program exited with errors");
@@ -46,8 +46,8 @@ impl Cmd {
 
             Cmd::Exec { source } => match source {
                 Some(source) => {
-                    let mut vm = VM::default();
                     let stdout = &mut io::stdout().lock();
+                    let mut vm = VM::new();
 
                     if let Err(e) = vm.run(source, stdout) {
                         report_err(source, e);
@@ -61,8 +61,8 @@ impl Cmd {
                         .lines()
                         .fold("".to_string(), |acc, line| acc + &line.unwrap() + "\n");
 
-                    let mut vm = VM::default();
                     let stdout = &mut io::stdout().lock();
+                    let mut vm = VM::new();
 
                     if let Err(e) = vm.run(&source, stdout) {
                         report_err(&source, e);

src/vm/compiler.rs

@@ -144,6 +144,33 @@ impl Compiler {
                     )?;
                     // This will consume both values just pushed on VM's stack
                     self.emit_u8(op::INHERIT, span);
+                } else {
+                    let base_class = String::from("Object");
+
+                    if class.name != base_class {
+                        if let Some(last) = self.class_ctx.last_mut() {
+                            last.has_super = true;
+                        }
+
+                        self.begin_scope();
+                        self.declare_local("super", &NO_SPAN)?;
+                        self.define_local();
+
+                        self.get_variable(
+                            &Identifier { name: base_class, package: None, depth: None },
+                            span,
+                            gc,
+                        )?;
+
+                        self.get_variable(
+                            &Identifier { name: class.name.clone(), package: None, depth: None },
+                            span,
+                            gc,
+                        )?;
+
+                        // This will consume both values just pushed on VM's stack
+                        self.emit_u8(op::INHERIT, span);
+                    }
                 }
 
                 // Initialize class fields, if they exist
@@ -205,9 +232,12 @@ impl Compiler {
                     self.emit_u8(op::POP, span);
                 }
 
-                if has_super {
-                    self.end_scope(&NO_SPAN);
+                if let Some(x) = self.class_ctx.last() {
+                    if x.has_super {
+                        self.end_scope(&NO_SPAN);
+                    }
                 }
+
                 self.class_ctx.pop().expect("attempted to pop the global context");
             }
             Stmt::Error => panic!("tried to compile despite parser errors"),

src/vm/disassembler.rs

@@ -446,44 +446,7 @@ mod tests {
               
             println(greeter.greet(\"World\")); // out: Hello World",
             concat!(
-                "0000 OP_CLASS            0 == 'Greeter'\n",
-                "0002 OP_DEFINE_GLOBAL    0 == 'Greeter'\n",
-                "0004 OP_GET_GLOBAL       0 == 'Greeter'\n",
-                "0006 OP_NIL\n",
-                "0007 OP_FIELD            1 == 'greeting'\n",
-                "0009 OP_POP\n",
-                "0010 OP_GET_GLOBAL       0 == 'Greeter'\n",
-                "0012 OP_CLOSURE          2 == '<fn init arity=1>'\n",
-                "| 0000 OP_GET_LOCAL        1\n",
-                "| 0002 OP_GET_LOCAL        0\n",
-                "| 0004 OP_SET_PROPERTY     0 == 'greeting'\n",
-                "| 0006 OP_POP\n",
-                "| 0007 OP_GET_LOCAL        0\n",
-                "| 0009 OP_RETURN\n",
-                "0014 OP_METHOD           3 == 'init'\n",
-                "0016 OP_CLOSURE          4 == '<fn greet arity=1>'\n",
-                "| 0000 OP_GET_LOCAL        0\n",
-                "| 0002 OP_GET_PROPERTY     0 == 'greeting'\n",
-                "| 0004 OP_CONSTANT         1 == ' '\n",
-                "| 0006 OP_ADD\n",
-                "| 0007 OP_GET_LOCAL        1\n",
-                "| 0009 OP_ADD\n",
-                "| 0010 OP_RETURN\n",
-                "0018 OP_METHOD           5 == 'greet'\n",
-                "0020 OP_POP\n",
-                "0021 OP_GET_GLOBAL       0 == 'Greeter'\n",
-                "0023 OP_CONSTANT         6 == 'Hello'\n",
-                "0025 OP_CALL             1\n",
-                "0027 OP_DEFINE_GLOBAL    7 == 'greeter'\n",
-                "0029 OP_GET_GLOBAL       8 == 'println'\n",
-                "0031 OP_GET_GLOBAL       7 == 'greeter'\n",
-                "0033 OP_GET_PROPERTY     5 == 'greet'\n",
-                "0035 OP_CONSTANT         9 == 'World'\n",
-                "0037 OP_CALL             1\n",
-                "0039 OP_CALL             1\n",
-                "0041 OP_POP\n",
-                "0042 OP_NIL\n",
-                "0043 OP_RETURN\n",
+                "0000 OP_CLASS            0 == 'Greeter'\n0002 OP_DEFINE_GLOBAL    0 == 'Greeter'\n0004 OP_GET_GLOBAL       1 == 'Object'\n0006 OP_GET_GLOBAL       0 == 'Greeter'\n0008 OP_INHERIT\n0009 OP_GET_GLOBAL       0 == 'Greeter'\n0011 OP_NIL\n0012 OP_FIELD            2 == 'greeting'\n0014 OP_POP\n0015 OP_GET_GLOBAL       0 == 'Greeter'\n0017 OP_CLOSURE          3 == '<fn init arity=1>'\n| 0000 OP_GET_LOCAL        1\n| 0002 OP_GET_LOCAL        0\n| 0004 OP_SET_PROPERTY     0 == 'greeting'\n| 0006 OP_POP\n| 0007 OP_GET_LOCAL        0\n| 0009 OP_RETURN\n0019 OP_METHOD           4 == 'init'\n0021 OP_CLOSURE          5 == '<fn greet arity=1>'\n| 0000 OP_GET_LOCAL        0\n| 0002 OP_GET_PROPERTY     0 == 'greeting'\n| 0004 OP_CONSTANT         1 == ' '\n| 0006 OP_ADD\n| 0007 OP_GET_LOCAL        1\n| 0009 OP_ADD\n| 0010 OP_RETURN\n0023 OP_METHOD           6 == 'greet'\n0025 OP_POP\n0026 OP_POP\n0027 OP_GET_GLOBAL       0 == 'Greeter'\n0029 OP_CONSTANT         7 == 'Hello'\n0031 OP_CALL             1\n0033 OP_DEFINE_GLOBAL    8 == 'greeter'\n0035 OP_GET_GLOBAL       9 == 'println'\n0037 OP_GET_GLOBAL       8 == 'greeter'\n0039 OP_GET_PROPERTY     6 == 'greet'\n0041 OP_CONSTANT        10 == 'World'\n0043 OP_CALL             1\n0045 OP_CALL             1\n0047 OP_POP\n0048 OP_NIL\n0049 OP_RETURN\n"
             )
         ),
     }

src/vm/mod.rs

@@ -10,8 +10,9 @@ mod value;
 
 use std::hash::BuildHasherDefault;
 use std::io::Write;
-use std::{mem, ptr};
+use std::{fs, mem, ptr};
 
+use anyhow::Context;
 use arrayvec::ArrayVec;
 pub use compiler::Compiler;
 pub use disassembler::Disassembler;
@@ -36,6 +37,8 @@ const FRAMES_MAX: usize = 64;
 const STACK_MAX: usize = FRAMES_MAX * STACK_MAX_PER_FRAME;
 const STACK_MAX_PER_FRAME: usize = u8::MAX as usize + 1;
 
+const PRELOADED_LOCKS_LIBS: &'static [&'static str] = &["res/lib/locks.locks"];
+
 #[derive(Debug)]
 pub struct VM {
     pub globals: HashMap<*mut ObjectString, Value, BuildHasherDefault<FxHasher>>,
@@ -69,12 +72,43 @@ pub struct VM {
 }
 
 impl VM {
+    pub fn new() -> VM {
+        let vm = VM::default();
+
+        vm
+    }
+
     pub fn run(&mut self, source: &str, stdout: &mut impl Write) -> Result<(), Vec<ErrorS>> {
+        let mut errors: Vec<ErrorS> = vec![];
+
+        for &path in PRELOADED_LOCKS_LIBS.into_iter() {
+            let source =
+                fs::read_to_string(&path).with_context(|| format!("could not read file: {path}"));
+
+            if let Ok(source) = source {
+                if let Err(mut errs) = self.load(&source, stdout) {
+                    errors.append(&mut errs);
+                }
+            }
+        }
+
+        if let Err(mut errs) = self.load(&source, stdout) {
+            errors.append(&mut errs);
+        }
+
+        if errors.len() > 0 {
+            return Err(errors);
+        }
+
+        Ok(())
+    }
+
+    fn load(&mut self, source: &str, stdout: &mut impl Write) -> Result<(), Vec<ErrorS>> {
         // This will change with each call to `run`
         let offset = self.source.len();
 
         // Add current source to self.source
-        // This helps us keep track of what the offset should be on future calls to `run`
+        // This helps us keep track of what the offset should be on future calls to `load`
         self.source.reserve(source.len() + 1);
         self.source.push_str(source);
         self.source.push('\n');