lox implementations
Implementations of the lox language from Crafting Interpreters
treewalk/ is the treewalk interpreter implementation
bytecode/ is the bytecode interpreter implementation
Both are written in zig 0.11.0.
More information for each interpreter is in each directory.
Example Output
This output is from the interpreter in bytecode/.
From 2a6c616
$ zig build run -- ./examples/breakfast.lox
--------------------------- ./examples/breakfast.lox ---------------------------
var food = "toast";
var beverage = "coffee";
var day = "saturday";
if (day == "saturday") {
food = "waffles";
}
var breakfast = food + " with " + beverage;
print breakfast;
-------------------------------- constants table -------------------------------
00: food
01: toast
02: beverage
03: coffee
04: day
05: saturday
06: day
07: saturday
08: food
09: waffles
0a: breakfast
0b: food
0c: with
0d: beverage
0e: breakfast
------------------------------- compiled bytecode ------------------------------
0x0000: 01 01 10 00 01 03 10 02 01 05 10 04 11 06 01 07
0x0010: 0b 18 00 09 0f 01 09 12 08 0f 17 00 01 0f 11 0b
0x0020: 01 0c 03 11 0d 03 10 0a 11 0e 0e 07 00
----------------------------------- <script> -----------------------------------
offset byte line meaning encoded data
1 var food = "toast";
0x0000 0x01 constant |
0x0001 0x01 (constant) "toast" |
0x0002 0x10 define_global |
0x0003 0x00 (constant) "food" |
2 var beverage = "coffee";
0x0004 0x01 constant |
0x0005 0x03 (constant) "coffee" |
0x0006 0x10 define_global |
0x0007 0x02 (constant) "beverage" |
4 var day = "saturday";
0x0008 0x01 constant |
0x0009 0x05 (constant) "saturday" |
0x000a 0x10 define_global |
0x000b 0x04 (constant) "day" |
5 if (day == "saturday") {
0x000c 0x11 get_global |
0x000d 0x06 (constant) "day" |
0x000e 0x01 constant |
0x000f 0x07 (constant) "saturday" |
0x0010 0x0b equal |
0x0011 0x18 jump_if_false 0x0011 -> 0x001d |
0x0012 0x00 (jump hi byte) |
0x0013 0x09 (jump lo byte) |
0x0014 0x0f pop |
6 food = "waffles";
0x0015 0x01 constant |
0x0016 0x09 (constant) "waffles" |
0x0017 0x12 set_global |
0x0018 0x08 (constant) "food" |
0x0019 0x0f pop |
7 }
0x001a 0x17 jump 0x001a -> 0x001e |
0x001b 0x00 (jump hi byte) |
0x001c 0x01 (jump lo byte) |
0x001d 0x0f pop |
9 var breakfast = food + " with " + beverage;
0x001e 0x11 get_global |
0x001f 0x0b (constant) "food" |
0x0020 0x01 constant |
0x0021 0x0c (constant) " with " |
0x0022 0x03 add |
0x0023 0x11 get_global |
0x0024 0x0d (constant) "beverage" |
0x0025 0x03 add |
0x0026 0x10 define_global |
0x0027 0x0a (constant) "breakfast" |
11 print breakfast;
0x0028 0x11 get_global |
0x0029 0x0e (constant) "breakfast" |
0x002a 0x0e print |
12
0x002b 0x07 nil |
0x002c 0x00 return |
-------------------------------- execution trace -------------------------------
offset byte line meaning encoded data stack before inst. exec.
1 var food = "toast";
0x0000 0x01 constant | [ <fn <script>> ]
0x0001 0x01 (constant) "toast" | [ <fn <script>> ]
0x0002 0x10 define_global | [ <fn <script>> ][ toast ]
0x0003 0x00 (constant) "food" | [ <fn <script>> ][ toast ]
2 var beverage = "coffee";
0x0004 0x01 constant | [ <fn <script>> ]
0x0005 0x03 (constant) "coffee" | [ <fn <script>> ]
0x0006 0x10 define_global | [ <fn <script>> ][ coffee ]
0x0007 0x02 (constant) "beverage" | [ <fn <script>> ][ coffee ]
4 var day = "saturday";
0x0008 0x01 constant | [ <fn <script>> ]
0x0009 0x05 (constant) "saturday" | [ <fn <script>> ]
0x000a 0x10 define_global | [ <fn <script>> ][ saturday ]
0x000b 0x04 (constant) "day" | [ <fn <script>> ][ saturday ]
5 if (day == "saturday") {
0x000c 0x11 get_global | [ <fn <script>> ]
0x000d 0x06 (constant) "day" | [ <fn <script>> ]
0x000e 0x01 constant | [ <fn <script>> ][ saturday ]
0x000f 0x07 (constant) "saturday" | [ <fn <script>> ][ saturday ]
0x0010 0x0b equal | [ <fn <script>> ][ saturday ][ saturday ]
0x0011 0x18 jump_if_false 0x0011 -> 0x001d | [ <fn <script>> ][ true ]
0x0012 0x00 (jump hi byte) | [ <fn <script>> ][ true ]
0x0013 0x09 (jump lo byte) | [ <fn <script>> ][ true ]
0x0014 0x0f pop | [ <fn <script>> ][ true ]
6 food = "waffles";
0x0015 0x01 constant | [ <fn <script>> ]
0x0016 0x09 (constant) "waffles" | [ <fn <script>> ]
0x0017 0x12 set_global | [ <fn <script>> ][ waffles ]
0x0018 0x08 (constant) "food" | [ <fn <script>> ][ waffles ]
0x0019 0x0f pop | [ <fn <script>> ][ waffles ]
7 }
0x001a 0x17 jump 0x001a -> 0x001e | [ <fn <script>> ]
0x001b 0x00 (jump hi byte) | [ <fn <script>> ]
0x001c 0x01 (jump lo byte) | [ <fn <script>> ]
9 var breakfast = food + " with " + beverage;
0x001e 0x11 get_global | [ <fn <script>> ]
0x001f 0x0b (constant) "food" | [ <fn <script>> ]
0x0020 0x01 constant | [ <fn <script>> ][ waffles ]
0x0021 0x0c (constant) " with " | [ <fn <script>> ][ waffles ]
0x0022 0x03 add | [ <fn <script>> ][ waffles ][ with ]
0x0023 0x11 get_global | [ <fn <script>> ][ waffles with ]
0x0024 0x0d (constant) "beverage" | [ <fn <script>> ][ waffles with ]
0x0025 0x03 add | [ <fn <script>> ][ waffles with ][ coffee ]
0x0026 0x10 define_global | [ <fn <script>> ][ waffles with coffee ]
0x0027 0x0a (constant) "breakfast" | [ <fn <script>> ][ waffles with coffee ]
11 print breakfast;
0x0028 0x11 get_global | [ <fn <script>> ]
0x0029 0x0e (constant) "breakfast" | [ <fn <script>> ]
0x002a 0x0e print | [ <fn <script>> ][ waffles with coffee ]
waffles with coffee
12
0x002b 0x07 nil | [ <fn <script>> ]
0x002c 0x00 return | [ <fn <script>> ][ (nil) ]