tuple patterns now use jump_stub and patch_jump, with 16 bit jump values

src/compiler.rs

@@ -261,13 +261,20 @@ impl Chunk {
                 *i += 1;
             }
             PushBinding | MatchTuple | MatchList | MatchDict | LoadDictValue | PushTuple
-            | PushBox | Jump | JumpIfFalse | JumpIfTrue | JumpIfNoMatch | JumpIfMatch
-            | JumpBack | JumpIfZero | MatchDepth | PopN | StoreAt | Call | SetUpvalue
-            | GetUpvalue | Partial | MatchString | PushStringMatches => {
+            | PushBox | MatchDepth | PopN | StoreAt | Call | SetUpvalue | GetUpvalue | Partial
+            | MatchString | PushStringMatches => {
                 let next = self.bytecode[*i + 1];
                 println!("{i:04}: {:16} {next:03}", op.to_string());
                 *i += 1;
             }
+            Jump | JumpIfFalse | JumpIfTrue | JumpIfNoMatch | JumpIfMatch | JumpBack
+            | JumpIfZero => {
+                let high = self.bytecode[*i + 1];
+                let low = self.bytecode[*i + 2];
+                let len = ((high as u16) << 8) + low as u16;
+                println!("{i:04}: {:16} {len:05}", op.to_string());
+                *i += 2;
+            }
         }
     }
 
@@ -395,6 +402,29 @@ impl<'a> Compiler<'a> {
         self.span = root_span;
     }
 
+    fn jump(&mut self, op: Op, len: usize) {
+        let low = len as u8;
+        let high = (len >> 8) as u8;
+        self.emit_op(op);
+        self.chunk.bytecode.push(high);
+        self.chunk.bytecode.push(low);
+    }
+
+    fn jump_stub(&mut self, op: Op) -> usize {
+        let out = self.chunk.bytecode.len();
+        self.emit_op(op);
+        self.emit_byte(0xff);
+        self.emit_byte(0xff);
+        out
+    }
+
+    fn patch_jump(&mut self, i: usize, len: usize) {
+        let low = len as u8;
+        let high = (len >> 8) as u8;
+        self.chunk.bytecode[i + 1] = high;
+        self.chunk.bytecode[i + 2] = low;
+    }
+
     fn emit_constant(&mut self, val: Value) {
         let const_idx = if let Some(idx) = self.chunk.constants.iter().position(|v| *v == val) {
             idx
@@ -568,18 +598,26 @@ impl<'a> Compiler<'a> {
             }
             Keyword(s) => self.emit_constant(Value::Keyword(s)),
             Block(lines) => {
+                // increase the scope
                 self.scope_depth += 1;
+                // stash the stack depth
                 let stack_depth = self.stack_depth;
+                // evaluate all the lines but the last
                 for expr in lines.iter().take(lines.len() - 1) {
-                    if is_binding(expr) {
-                        self.visit(expr);
-                    } else {
+                    // evaluate the expression
                     self.visit(expr);
+                    // if it doesn't bind a name, pop the result from the stack
+                    if !is_binding(expr) {
                         self.pop();
                     }
                 }
+
+                // now, evaluate the last expression in the block
                 let last_expr = lines.last().unwrap();
                 match last_expr {
+                    // if the last expression is a let form,
+                    // return the evaluated rhs instead of whatever is last on the stack
+                    // we do this by pretending it's a binding
                     (Let(patt, expr), _) => {
                         self.match_depth = 0;
                         self.emit_op(Op::ResetMatch);
@@ -591,14 +629,20 @@ impl<'a> Compiler<'a> {
                         self.emit_byte(expr_pos);
                         self.stack_depth += 1;
                     }
+                    // otherwise, just evaluate it and leave the value on the stack
                     _ => {
                         self.visit(last_expr);
                     }
                 }
-                self.stack_depth += 1;
-                self.emit_op(Op::Store);
-                self.scope_depth -= 1;
 
+                // we've made a new value, so increase the stack level in the compiler
+                self.stack_depth += 1;
+
+                // store the value in the return register
+                self.emit_op(Op::Store);
+
+                // reset the scope
+                self.scope_depth -= 1;
                 while let Some(binding) = self.bindings.last() {
                     if binding.depth > self.scope_depth {
                         self.bindings.pop();
@@ -606,29 +650,24 @@ impl<'a> Compiler<'a> {
                         break;
                     }
                 }
-                // reset stack
-                while self.stack_depth > stack_depth + 1 {
-                    self.pop();
-                }
+                // reset the stack
+                self.pop_n(self.stack_depth - stack_depth - 1);
+                // load the value from the return register
                 self.emit_op(Op::Load);
             }
             If(cond, then, r#else) => {
                 self.visit(cond);
-                let jif_idx = self.len();
-                self.emit_op(Op::JumpIfFalse);
-                self.emit_byte(0xff);
+                let jif_idx = self.jump_stub(Op::JumpIfFalse);
                 self.stack_depth -= 1;
                 self.visit(then);
-                let jump_idx = self.len();
-                self.emit_op(Op::Jump);
-                self.emit_byte(0xff);
+                let jump_idx = self.jump_stub(Op::Jump);
                 self.visit(r#else);
                 self.stack_depth -= 1;
                 let end_idx = self.len();
                 let jif_offset = jump_idx - jif_idx;
-                let jump_offset = end_idx - jump_idx - 2;
-                self.chunk.bytecode[jif_idx + 1] = jif_offset as u8;
-                self.chunk.bytecode[jump_idx + 1] = jump_offset as u8;
+                let jump_offset = end_idx - jump_idx - 1;
+                self.patch_jump(jif_idx, jif_offset);
+                self.patch_jump(jump_idx, jump_offset);
             }
             Let(patt, expr) => {
                 self.match_depth = 0;
@@ -679,36 +718,54 @@ impl<'a> Compiler<'a> {
                 self.match_constant(Value::Interned(s));
             }
             TuplePattern(members) => {
+                // first, test the tuple against length
                 self.emit_op(Op::MatchTuple);
                 self.emit_byte(members.len());
-                self.emit_op(Op::JumpIfNoMatch);
-                let before_load_tup_idx = self.len();
-                self.emit_byte(0xff);
+                // skip everything if tuple lengths don't match
+                let before_load_tup_idx = self.jump_stub(Op::JumpIfNoMatch);
+
+                // set up the per-member conditional logic
                 let mut jump_idxes = vec![];
-                self.match_depth += members.len();
+                // stash match_depth, and set it to the tuple len
+                let match_depth = self.match_depth;
+                self.match_depth = members.len();
+
+                // load the tuple and update the stack len
                 self.emit_op(Op::LoadTuple);
                 self.stack_depth += members.len();
+
+                // visit each member
                 for member in members {
+                    // reduce the match depth to start
                     self.match_depth -= 1;
                     self.emit_op(Op::MatchDepth);
                     self.emit_byte(self.match_depth);
+                    // visit the pattern member
                     self.visit(member);
-                    self.emit_op(Op::JumpIfNoMatch);
-                    jump_idxes.push(self.len());
-                    self.emit_byte(0xff);
+                    // and jump if there's no match
+                    jump_idxes.push(self.jump_stub(Op::JumpIfNoMatch));
                 }
-                self.emit_op(Op::Jump);
-                let jump_idx = self.len();
-                self.emit_byte(0xff);
+
+                // if we get here--not having jumped on no match--we're matched; jump the "no match" code
+                self.match_depth = match_depth + members.len();
+                let jump_idx = self.jump_stub(Op::Jump);
+
+                // patch up the previous no match jumps to jump to clean-up code
                 for idx in jump_idxes {
-                    self.chunk.bytecode[idx] = (self.len() - idx) as u8 - 1;
+                    self.patch_jump(idx, self.len() - idx - 2)
                 }
-                for _ in 0..members.len() {
-                    self.emit_op(Op::Pop);
-                }
-                self.chunk.bytecode[before_load_tup_idx] =
-                    (self.len() - before_load_tup_idx) as u8 - 1;
-                self.chunk.bytecode[jump_idx] = (self.len() - jump_idx) as u8 - 1;
+                // pop everything that was pushed
+                // don't change the compiler stack representation, tho
+                // we need this as cleanup code with no matches
+                // the compiler should still have access to the bindings in this pattern
+                self.emit_op(Op::PopN);
+                self.emit_byte(members.len());
+
+                // patch up the tuple length match jump
+                self.patch_jump(before_load_tup_idx, self.len() - before_load_tup_idx - 3);
+
+                // patch up the yes-matches unconditional jump
+                self.patch_jump(jump_idx, self.len() - jump_idx - 3);
             }
             ListPattern(members) => {
                 self.emit_op(Op::MatchList);

src/main.rs

@@ -20,7 +20,6 @@ mod validator;
 mod compiler;
 use crate::compiler::Compiler;
 
-mod pattern;
 mod value;
 
 mod vm;
@@ -75,23 +74,8 @@ pub fn run(src: &'static str) {
 
 pub fn main() {
     // env::set_var("RUST_BACKTRACE", "1");
-    //     let src = "
-    // let x = {
-    //     match #{:a 1, :b 2, :c 3} with {
-    //         #{a} -> :one
-    //         #{a, b, :c 3} -> :two
-    //         #{a, b, c} -> :three
-    //         (1, 2, 3) -> :thing
-    //         (4, 5, (6, 7, a)) -> if or (true, false, false, true) then :thing_1 else :thing_2
-    //         ([:a, :b, :c, [:d, [:e, (:f, :g)]]]) -> if or (true, false, false, true) then :thing_1 else :thing_2
-    //     }
-    // }
-
-    //    ";
-    //     run(src);
-    let a: u16 = 14261;
-    let b_high: u8 = (a >> 8) as u8;
-    let b_low: u8 = a as u8;
-    let c: u16 = ((b_high as u16) << 8) + b_low as u16;
-    println!("{a} // {b_high}/{b_low} // {c}");
+    let src = "
+let ((1)) = ((1))
+   ";
+    run(src);
 }

src/vm.rs

@@ -57,7 +57,7 @@ impl CallFrame {
         let Value::Fn(ref function) = self.function else {
             unreachable!()
         };
-        &function.chunk(self.arity)
+        function.chunk(self.arity)
     }
 }
 
@@ -76,6 +76,11 @@ impl fmt::Display for CallFrame {
     }
 }
 
+fn combine_bytes(high: u8, low: u8) -> usize {
+    let out = ((high as u16) << 8) + low as u16;
+    out as usize
+}
+
 pub struct Vm {
     pub stack: Vec<Value>,
     pub call_stack: Vec<CallFrame>,
@@ -205,46 +210,61 @@ impl Vm {
                     self.ip += 2;
                 }
                 Jump => {
-                    let jump_len = self.chunk().bytecode[self.ip + 1];
-                    self.ip += jump_len as usize + 2;
+                    let high = self.chunk().bytecode[self.ip + 1];
+                    let low = self.chunk().bytecode[self.ip + 2];
+                    let jump_len = combine_bytes(high, low);
+                    // let jump_len = self.chunk().bytecode[self.ip + 1];
+                    self.ip += jump_len + 3;
                 }
                 JumpBack => {
-                    let jump_len = self.chunk().bytecode[self.ip + 1];
-                    self.ip -= jump_len as usize;
+                    let high = self.chunk().bytecode[self.ip + 1];
+                    let low = self.chunk().bytecode[self.ip + 2];
+                    let jump_len = combine_bytes(high, low);
+                    // let jump_len = self.chunk().bytecode[self.ip + 1];
+                    self.ip -= jump_len;
                 }
                 JumpIfFalse => {
-                    let jump_len = self.chunk().bytecode[self.ip + 1];
+                    let high = self.chunk().bytecode[self.ip + 1];
+                    let low = self.chunk().bytecode[self.ip + 2];
+                    let jump_len = combine_bytes(high, low);
+                    // let jump_len = self.chunk().bytecode[self.ip + 1];
                     let cond = self.pop();
                     match cond {
                         Value::Nil | Value::False => {
-                            self.ip += jump_len as usize + 2;
+                            self.ip += jump_len + 3;
                         }
                         _ => {
-                            self.ip += 2;
+                            self.ip += 3;
                         }
                     }
                 }
                 JumpIfTrue => {
-                    let jump_len = self.chunk().bytecode[self.ip + 1];
+                    let high = self.chunk().bytecode[self.ip + 1];
+                    let low = self.chunk().bytecode[self.ip + 2];
+                    let jump_len = combine_bytes(high, low);
+                    // let jump_len = self.chunk().bytecode[self.ip + 1];
                     let cond = self.pop();
                     match cond {
                         Value::Nil | Value::False => {
-                            self.ip += 2;
+                            self.ip += 3;
                         }
                         _ => {
-                            self.ip += jump_len as usize + 2;
+                            self.ip += jump_len + 3;
                         }
                     }
                 }
                 JumpIfZero => {
-                    let jump_len = self.chunk().bytecode[self.ip + 1];
+                    let high = self.chunk().bytecode[self.ip + 1];
+                    let low = self.chunk().bytecode[self.ip + 2];
+                    let jump_len = combine_bytes(high, low);
+                    // let jump_len = self.chunk().bytecode[self.ip + 1];
                     let cond = self.pop();
                     match cond {
                         Value::Number(x) if x <= 0.0 => {
-                            self.ip += jump_len as usize + 2;
+                            self.ip += jump_len as usize + 3;
                         }
                         Value::Number(..) => {
-                            self.ip += 2;
+                            self.ip += 3;
                         }
                         _ => return self.panic("repeat requires a number"),
                     }
@@ -542,19 +562,25 @@ impl Vm {
                     self.ip += 1;
                 }
                 JumpIfNoMatch => {
-                    let jump_len = self.chunk().bytecode[self.ip + 1] as usize;
+                    let high = self.chunk().bytecode[self.ip + 1];
+                    let low = self.chunk().bytecode[self.ip + 2];
+                    let jump_len = combine_bytes(high, low);
+                    // let jump_len = self.chunk().bytecode[self.ip + 1] as usize;
                     if !self.matches {
-                        self.ip += jump_len + 2;
+                        self.ip += jump_len + 3;
                     } else {
-                        self.ip += 2;
+                        self.ip += 3;
                     }
                 }
                 JumpIfMatch => {
-                    let jump_len = self.chunk().bytecode[self.ip + 1] as usize;
+                    let high = self.chunk().bytecode[self.ip + 1];
+                    let low = self.chunk().bytecode[self.ip + 2];
+                    let jump_len = combine_bytes(high, low);
+                    // let jump_len = self.chunk().bytecode[self.ip + 1] as usize;
                     if self.matches {
-                        self.ip += jump_len + 2;
+                        self.ip += jump_len + 3;
                     } else {
-                        self.ip += 2;
+                        self.ip += 3;
                     }
                 }
                 TypeOf => {