chunk: split writing side-effects into own function

split writeConstant() into that and writeConstantRaw() for the places
where we don't want OP_CONSTANT written as well.

this caused a bug where doing `"some const string" + x` would cause an
unecessary OP_CONSTANT to be added for the x variable and would cause
the wrong result to be given.

 - main: reset stack on repl tick (?)
This commit is contained in:
Luna 2019-06-03 00:55:50 -03:00
parent 922f3c530c
commit 8bc220d2f8
4 changed files with 42 additions and 9 deletions

View file

@ -134,7 +134,7 @@ pub const Chunk = struct {
return self.constants.count - 1;
}
pub fn writeConstant(
pub fn writeConstantRaw(
self: *Chunk,
val: value.Value,
line: usize,
@ -143,10 +143,7 @@ pub const Chunk = struct {
var constant_idx = self.constants.count - 1;
if (constant_idx < 256) {
try self.write(OpCode.Constant, line);
var idx_small = @intCast(u8, constant_idx);
try self.write(idx_small, line);
return ConstantIndex{ .Small = idx_small };
} else {
var idx_u24: u24 = @intCast(u24, constant_idx);
@ -157,14 +154,35 @@ pub const Chunk = struct {
const v2: u8 = @intCast(u8, (idx_u24 >> 8) & mask);
const v3: u8 = @intCast(u8, (idx_u24 >> 16) & mask);
try self.write(OpCode.ConstantLong, line);
try self.write(v3, line);
try self.write(v2, line);
try self.write(v1, line);
return ConstantIndex{ .Long = []u8{ v3, v2, v1 } };
}
}
pub fn writeConstant(
self: *Chunk,
val: value.Value,
line: usize,
) !ConstantIndex {
var idx = try self.writeConstantRaw(val, line);
switch (idx) {
.Small => |idx_small| blk: {
try self.write(OpCode.Constant, line);
try self.write(idx_small, line);
break :blk;
},
.Long => |long_u8| blk: {
try self.write(OpCode.ConstantLong, line);
try self.write(long_u8[0], line);
try self.write(long_u8[1], line);
try self.write(long_u8[2], line);
},
else => unreachable,
}
return idx;
}
pub fn disassembleInstruction(
self: *Chunk,
stdout: var,

View file

@ -253,7 +253,13 @@ pub const Compiler = struct {
}
fn namedVariable(self: *Compiler, tok: *Token) !void {
var idx = try self.identifierConstant(tok);
// writeConstant always writes OP_CODE which may be not
// what we want, so.
var idx = try self.currentChunk().writeConstantRaw(values.ObjVal(try objects.copyString(
self.vmach,
tok.lexeme,
)), tok.line);
try self.emitConstWithIndex(
chunks.OpCode.GetGlobal,
chunks.OpCode.GetGlobalLong,

View file

@ -85,6 +85,8 @@ fn runPrompt(allocator: *Allocator) !void {
else => return err,
}
};
vmach.resetStack();
}
}

View file

@ -237,6 +237,13 @@ pub const VM = struct {
fn doGetGlobal(self: *VM, name: []u8) !void {
var kv_opt = self.globals.get(name);
// take out the OP_CONST loaded before, if any
// note this is a complete hack.
//var val = self.peek(0);
//if (val.vtype == .Object and val.as.Object.otype == .String and std.mem.compare(u8, val.as.Object.value.String, name) == .Equal) {
// _ = self.pop();
//}
if (kv_opt) |kv| {
try self.push(kv.value);
} else {