level 1 compilation woo!

i'm sure 1 test will be enough what could go wrong hahahaha

bf.zig

@@ -2,7 +2,150 @@
 const std = @import("std");
 const io = std.io;
 const fs = std.fs;
+const mem = std.mem;
 const process = std.process;
+const testing = std.testing;
+const ArrayList = std.ArrayList;
+
+const Level1 = union(enum) {
+    // think about it... i hope
+    inc: i16,
+    shift: i16,
+    // u8 because why would we be reading to/writing from the same cell 256 times in a row
+    // well, might as well use the extra space (union is bigger than its biggest member)
+    in: u16,
+    out: u16,
+    loop_start,
+    loop_end,
+
+    const Self = @This();
+    fn pointless(self: Self) bool {
+        return switch (self) {
+            .inc, .shift => |n| n == 0,
+            .in, .out => |n| n == 0,
+            else => false,
+        };
+    }
+};
+
+const Level2 = union(enum) {
+    inc: i16,
+    shift: i16,
+    in: u16,
+    out: u16,
+    // only difference
+    // u24s because i arbitrarily chose 2^24 as the limit
+    // maybe u32 would be more efficient idk this union should fit in a u32
+    // hm we can probably go way lower bc level1 is so much more compact than prog_unfiltered
+    // shouldn't be necessary
+    loop_start: u24,
+    loop_end: u24,
+};
+
+// we'll do the discarding of comment chars here
+fn compileLevel1(allocator: mem.Allocator, src: []const u8) !ArrayList(Level1) {
+    var cur: ?Level1 = null;
+    var out = ArrayList(Level1).init(allocator);
+
+    for (src) |b| {
+        switch (b) {
+            '+', '-' => {
+                const n: i16 = if (b == '+') 1 else -1;
+                if (cur) |*ins| {
+                    switch (ins.*) {
+                        .inc => |*ns| ns.* += n,
+                        else => {
+                            if (!ins.pointless()) try out.append(ins.*);
+                            cur = .{ .inc = n };
+                        },
+                    }
+                } else {
+                    cur = .{ .inc = n };
+                }
+            },
+            '>', '<' => {
+                const n: i16 = if (b == '>') 1 else -1;
+                if (cur) |*ins| {
+                    switch (ins.*) {
+                        .shift => |*ns| ns.* += n,
+                        else => {
+                            if (!ins.pointless()) try out.append(ins.*);
+                            cur = .{ .shift = n };
+                        },
+                    }
+                } else {
+                    cur = .{ .shift = n };
+                }
+            },
+            '[', ']' => {
+                if (cur) |ins| {
+                    if (!ins.pointless()) try out.append(ins);
+                    cur = null;
+                }
+                try out.append(if (b == '[') .loop_start else .loop_end);
+            },
+            ',' => {
+                if (cur) |*ins| {
+                    switch (ins.*) {
+                        .in => |*ns| ns.* += 1,
+                        else => {
+                            if (!ins.pointless()) try out.append(ins.*);
+                            cur = .{ .in = 1 };
+                        },
+                    }
+                } else {
+                    cur = .{ .in = 1 };
+                }
+            },
+            '.' => {
+                if (cur) |*ins| {
+                    switch (ins.*) {
+                        .out => |*ns| ns.* += 1,
+                        else => {
+                            if (!ins.pointless()) try out.append(ins.*);
+                            cur = .{ .out = 1 };
+                        },
+                    }
+                } else {
+                    cur = .{ .out = 1 };
+                }
+            },
+            else => {},
+        }
+    }
+
+    if (cur) |ins| {
+        if (!ins.pointless()) try out.append(ins);
+    }
+
+    return out;
+}
+
+test "level 1" {
+    const src = "+++-- [ >><<< +-  ] ...,,,";
+
+    const level1 = try compileLevel1(testing.allocator, src);
+    defer level1.deinit();
+
+    std.debug.print("{any}\n", .{level1.items});
+
+    const should_be = [_]Level1{
+        .{ .inc = 1 },
+        .loop_start,
+        .{ .shift = -1 },
+        .loop_end,
+        .{ .out = 3 },
+        .{ .in = 3 },
+    };
+    try testing.expectEqual(should_be.len, level1.items.len);
+
+    for (
+        level1.items,
+        &should_be,
+    ) |a, b| {
+        try testing.expectEqual(a, b);
+    }
+}
 
 pub fn main() !void {
     var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
@@ -32,8 +175,8 @@ pub fn main() !void {
         }
     }
 
-    var mem = try allocator.alloc(u8, 1 << 16);
-    for (mem) |*m| {
+    var memory = try allocator.alloc(u8, 1 << 16);
+    for (memory) |*m| {
         m.* = 0;
     }
     var mp: u16 = 0;
@@ -41,12 +184,12 @@ pub fn main() !void {
 
     while (ip < prog_len) {
         switch (prog[ip]) {
-            '+' => mem[mp] +%= 1,
-            '-' => mem[mp] -%= 1,
+            '+' => memory[mp] +%= 1,
+            '-' => memory[mp] -%= 1,
             '>' => mp +%= 1,
             '<' => mp -%= 1,
             '[' => {
-                if (mem[mp] == 0) {
+                if (memory[mp] == 0) {
                     var depth: i16 = 1;
                     ip += 1;
                     while (depth > 0) : (ip += 1) {
@@ -60,7 +203,7 @@ pub fn main() !void {
                 }
             },
             ']' => {
-                if (mem[mp] != 0) {
+                if (memory[mp] != 0) {
                     var depth: i16 = 1;
                     ip -= 1;
                     while (depth > 0) : (ip -= 1) {
@@ -73,8 +216,8 @@ pub fn main() !void {
                     ip += 1;
                 }
             },
-            '.' => try out.writeByte(mem[mp]),
-            ',' => mem[mp] = in.readByte() catch 0,
+            ',' => memory[mp] = in.readByte() catch 0,
+            '.' => try out.writeByte(memory[mp]),
             else => unreachable,
         }
         ip += 1;