ser python backend, somewhat tested but could break

ser/codegen.h

@@ -8,6 +8,11 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#define INDENT 4
+
+#define MSG_MAGIC_START 0xCAFEF00DBEEFDEADUL
+#define MSG_MAGIC_END 0xF00DBEEFCAFEDEADUL
+
 // Struct used to define the relative alignment when working with structs
 typedef struct {
     Alignment align;

ser/codegen_c.c

@@ -5,8 +5,6 @@
 
 #include <stddef.h>
 
-#define INDENT 4
-
 typedef enum {
     MTPointer,
     MTArray,
@@ -34,9 +32,9 @@ static inline const char *array_size_type(uint64_t size) {
     }
 }
 
-void write_field(Writer *w, Field f, Modifier *mods, size_t len, uint32_t indent);
+static void write_field(Writer *w, Field f, Modifier *mods, size_t len, uint32_t indent);
 // Wrte the *base* type type with indentation
-void write_type(Writer *w, TypeObject *type, uint32_t indent) {
+static void write_type(Writer *w, TypeObject *type, uint32_t indent) {
     if (type->kind == TypePrimitif) {
 #define _case(x, s) \
     case Primitif_##x: \
@@ -145,7 +143,7 @@ void write_type(Writer *w, TypeObject *type, uint32_t indent) {
 //   7.
 //       result = "char bar"
 
-void write_field(Writer *w, Field f, Modifier *mods, size_t len, uint32_t indent) {
+static void write_field(Writer *w, Field f, Modifier *mods, size_t len, uint32_t indent) {
     TypeObject *type = f.type;
     ModifierVec modifiers = vec_init();
     TypeObject *current = type;
@@ -185,7 +183,7 @@ void write_field(Writer *w, Field f, Modifier *mods, size_t len, uint32_t indent
     _vec_modifier_drop(modifiers);
 }
 
-void write_struct(Writer *w, StructObject *obj, void *_user_data) {
+static void write_struct(Writer *w, StructObject *obj, void *_user_data) {
     wt_format(w, "typedef struct %.*s {\n", obj->name.len, obj->name.ptr);
 
     for (size_t i = 0; i < obj->fields.len; i++) {
@@ -197,11 +195,11 @@ void write_struct(Writer *w, StructObject *obj, void *_user_data) {
     wt_format(w, "} %.*s;\n\n", obj->name.len, obj->name.ptr);
 }
 
-void write_align(Writer *w, const char *var, const Alignment align, size_t indent) {
+static void write_align(Writer *w, const char *var, const Alignment align, size_t indent) {
     wt_format(w, "%*s%s = (byte*)(((((uintptr_t)%s - 1) >> %u) + 1) << %u);\n", indent, "", var, var, align.po2, align.po2);
 }
 
-void write_accessor(Writer *w, TypeObject *base_type, FieldAccessor fa, bool ptr) {
+static void write_accessor(Writer *w, TypeObject *base_type, FieldAccessor fa, bool ptr) {
     if (fa.indices.len == 0)
         return;
 
@@ -251,7 +249,7 @@ void write_accessor(Writer *w, TypeObject *base_type, FieldAccessor fa, bool ptr
     }
 }
 
-bool is_field_accessor_heap_array(FieldAccessor fa, TypeObject *base_type) {
+static bool is_field_accessor_heap_array(FieldAccessor fa, TypeObject *base_type) {
     if (fa.indices.len == 0)
         return base_type->kind == TypeArray && base_type->type.array.heap;
 
@@ -282,7 +280,7 @@ bool is_field_accessor_heap_array(FieldAccessor fa, TypeObject *base_type) {
     return t->kind == TypeArray && t->type.array.heap;
 }
 
-void write_type_serialization(
+static void write_type_serialization(
     Writer *w, const char *base, bool ptr, Layout *layout, CurrentAlignment al, Hashmap *layouts, size_t indent, size_t depth, bool always_inline
 ) {
     if (layout->fields.len == 0)
@@ -357,7 +355,7 @@ void write_type_serialization(
     }
 }
 
-void write_type_deserialization(
+static void write_type_deserialization(
     Writer *w, const char *base, bool ptr, Layout *layout, CurrentAlignment al, Hashmap *layouts, size_t indent, size_t depth, bool always_inline
 ) {
     if (layout->fields.len == 0)
@@ -447,7 +445,7 @@ void write_type_deserialization(
     }
 }
 
-int write_type_free(Writer *w, const char *base, TypeObject *type, Hashmap *layouts, size_t indent, size_t depth, bool always_inline) {
+static int write_type_free(Writer *w, const char *base, TypeObject *type, Hashmap *layouts, size_t indent, size_t depth, bool always_inline) {
     if (type->kind == TypePrimitif) {
         return 0;
     } else if (type->kind == TypeArray) {
@@ -512,7 +510,7 @@ int write_type_free(Writer *w, const char *base, TypeObject *type, Hashmap *layo
     return 0;
 }
 
-void write_struct_func_decl(Writer *w, StructObject *obj, void *_user_data) {
+static void write_struct_func_decl(Writer *w, StructObject *obj, void *_user_data) {
     obj->has_funcs = true;
 
     StringSlice sname = obj->name;
@@ -523,7 +521,7 @@ void write_struct_func_decl(Writer *w, StructObject *obj, void *_user_data) {
     free(snake_case_name);
 }
 
-void write_struct_func(Writer *w, StructObject *obj, void *user_data) {
+static void write_struct_func(Writer *w, StructObject *obj, void *user_data) {
     Hashmap *layouts = user_data;
     // Retreive original TypeObject pointer from struct object pointer.
     TypeObject *t = (void *)((byte *)obj - offsetof(struct TypeObject, type));
@@ -562,7 +560,7 @@ void codegen_c(Writer *header, Writer *source, const char *name, Program *p) {
     char *uc_name = snake_case_to_screaming_snake_case((StringSlice){.ptr = name, .len = strlen(name)});
     wt_format(
         header,
-        "// Generated file, do not edit (its not like it'll explode if you do, but its better not to)\n"
+        "// Generated file\n"
         "#ifndef %s_H\n"
         "#define %s_H\n"
         "#include <stdint.h>\n"
@@ -573,16 +571,18 @@ void codegen_c(Writer *header, Writer *source, const char *name, Program *p) {
         "typedef uint64_t MsgMagic;\n"
         "\n"
         "#define MSG_MAGIC_SIZE sizeof(MsgMagic)\n"
-        "static const MsgMagic MSG_MAGIC_START = 0xCAFEF00DBEEFDEAD;\n"
+        "static const MsgMagic MSG_MAGIC_START = 0x%016lX;\n"
-        "static const MsgMagic MSG_MAGIC_END = 0xF00DBEEFCAFEDEAD;\n"
+        "static const MsgMagic MSG_MAGIC_END = 0x%016lX;\n"
         "\n",
         uc_name,
-        uc_name
+        uc_name,
+        MSG_MAGIC_START,
+        MSG_MAGIC_END
     );
     free(uc_name);
     wt_format(
         source,
-        "// Generated file, do not edit (its not like it'll explode if you do, but its better not to)\n"
+        "// Generated file\n"
         "#include \"%s.h\"\n"
         "#include <stdio.h>\n"
         "\n",

ser/codegen_python.c

@@ -0,0 +1,537 @@
+#include "codegen_python.h"
+
+#include <stddef.h>
+
+static void write_type_name(Writer *w, TypeObject *type, Hashmap *defined) {
+    if (type->kind == TypePrimitif) {
+#define _case(x, str) \
+    case Primitif_##x: \
+        wt_format(w, str); \
+        return
+        switch (type->type.primitif) {
+            _case(u8, "int");
+            _case(u16, "int");
+            _case(u32, "int");
+            _case(u64, "int");
+            _case(i8, "int");
+            _case(i16, "int");
+            _case(i32, "int");
+            _case(i64, "int");
+            _case(f32, "float");
+            _case(f64, "float");
+            _case(bool, "bool");
+            _case(char, "str");
+        }
+#undef _case
+    } else if (type->kind == TypeArray) {
+        // If we have an array of char
+        if (type->type.array.type->kind == TypePrimitif && type->type.array.type->type.primitif == Primitif_char) {
+            wt_format(w, "str");
+            return;
+        }
+        wt_format(w, "List[");
+        write_type_name(w, type->type.array.type, defined);
+        wt_format(w, "]");
+    } else if (type->kind == TypeStruct) {
+        StructObject *obj = (StructObject *)&type->type.struct_;
+        if (defined == NULL || hashmap_has(defined, &obj)) {
+            wt_write(w, obj->name.ptr, obj->name.len);
+        } else {
+            wt_format(w, "'%.*s'", obj->name.len, obj->name.ptr);
+        }
+    }
+}
+
+typedef enum {
+    Read,
+    Write,
+} Access;
+
+static void write_field_accessor(Writer *w, const char *base, FieldAccessor fa, TypeObject *type, Access access) {
+    if (fa.indices.len == 0) {
+        wt_format(w, "%s", base);
+        return;
+    }
+
+    BufferedWriter b = buffered_writer_init();
+    Writer *w2 = (Writer *)&b;
+
+    bool len = false;
+    wt_format(w2, "%s", base);
+    for (size_t i = 0; i < fa.indices.len; i++) {
+        uint64_t index = fa.indices.data[i];
+
+        if (type->kind == TypeStruct) {
+            StructObject *obj = (StructObject *)&type->type.struct_;
+            Field f = obj->fields.data[index];
+            wt_format(w2, ".%.*s", f.name.len, f.name.ptr);
+
+            type = f.type;
+        } else if (type->kind == TypeArray) {
+            if (type->type.array.sizing == SizingMax) {
+                len = index == 0;
+                break;
+            } else {
+                wt_format(w2, "[%lu]", index);
+                type = type->type.array.type;
+            }
+        }
+    }
+
+    if (len) {
+        if (access == Read) {
+            wt_format(w, "len(%.*s)", b.buf.len, b.buf.data);
+        } else {
+            CharVec buf = b.buf;
+            for (size_t i = 0; i < buf.len; i++) {
+                if (buf.data[i] == '.') {
+                    buf.data[i] = '_';
+                }
+            }
+            wt_write(w, buf.data, buf.len);
+            wt_format(w, "_len");
+        }
+    } else {
+        wt_write(w, b.buf.data, b.buf.len);
+    }
+
+    buffered_writer_drop(b);
+}
+
+static bool field_accessor_is_array_length(FieldAccessor fa, TypeObject *type) {
+    if (fa.indices.len == 0 || fa.indices.data[fa.indices.len - 1] != 0 || fa.type->kind != TypePrimitif)
+        return false;
+
+    for (size_t i = 0; i < fa.indices.len - 1; i++) {
+        uint64_t index = fa.indices.data[i];
+        if (type->kind == TypeStruct) {
+            StructObject *s = (StructObject *)&type->type.struct_;
+
+            type = s->fields.data[index].type;
+        } else if (type->kind == TypeArray) {
+            type = type->type.array.type;
+        }
+    }
+
+    return type->kind == TypeArray && type->type.array.sizing == SizingMax;
+}
+
+// Find the index of the FieldAccessor that points to the length of this array
+static uint64_t get_array_length_field_index(Layout *layout, FieldAccessor fa) {
+    size_t index = SIZE_MAX;
+    for (size_t j = 0; j < layout->fields.len && layout->fields.data[j].size != 0; j++) {
+        FieldAccessor f = layout->fields.data[j];
+        if (f.indices.len != fa.indices.len)
+            continue;
+
+        // Check the indices for equality, all but the last one should be equal
+        bool equal = true;
+        for (size_t k = 0; k < f.indices.len - 1; k++) {
+            if (f.indices.data[k] != fa.indices.data[k]) {
+                equal = false;
+                break;
+            }
+        }
+
+        if (equal && f.indices.data[f.indices.len - 1] == 0) {
+            index = j;
+            break;
+        }
+    }
+
+    if (index == SIZE_MAX) {
+        log_error("No length accessor for variable size array accessor");
+        exit(1);
+    }
+
+    return index;
+}
+
+static void write_type_uninit(Writer *u, TypeObject *type) {
+    if (type->kind == TypeStruct) {
+        StructObject *s = (StructObject *)&type->type.struct_;
+        for (size_t i = 0; i < s->fields.len; i++) {
+            Field f = s->fields.data[i];
+            if (f.type->kind == TypeStruct) {
+                StringSlice tname = f.type->type.struct_.name;
+                wt_format(u, "%*sself.%.*s = %.*s.uninit()\n", INDENT * 2, "", f.name.len, f.name.ptr, tname.len, tname.ptr);
+            } else if (f.type->kind == TypeArray) {
+                wt_format(u, "%*sself.%.*s = []\n", INDENT * 2, "", f.name.len, f.name.ptr);
+            }
+        }
+    }
+}
+
+static void write_type_funcs(
+    Writer *s,
+    Writer *d,
+    TypeObject *type,
+    const char *base,
+    CurrentAlignment al,
+    Hashmap *layouts,
+    size_t indent,
+    size_t depth,
+    bool always_inline
+) {
+    Layout *layout = hashmap_get(layouts, &(Layout){.type = type});
+    assert(layout != NULL, "Type has no layout");
+
+    if (layout->fields.len == 0)
+        return;
+
+    Alignment align = al.align;
+    size_t offset = calign_to(al, layout->fields.data[0].type->align);
+
+    if (offset > 0) {
+        wt_format(s, "%*sbuf += bytes(%lu)\n", indent, "", offset);
+        wt_format(d, "%*soff += %lu\n", indent, "", offset);
+    }
+
+    if (type->kind == TypeStruct && !always_inline) {
+        offset = calign_to(al, layout->type->align);
+        if (offset != 0) {
+            wt_format(s, "%*sbuf += bytes(%lu)\n", indent, "", offset);
+            wt_format(d, "%*soff = %lu\n", indent, "", offset);
+        }
+        wt_format(s, "%*s%s.serialize(buf)\n", indent, "", base);
+        wt_format(d, "%*soff += %s.deserialize(buf[off:])\n", indent, "", base);
+        return;
+    }
+
+    wt_format(s, "%*sbuf += pack('<", indent, "");
+    wt_format(d, "%*sxs%lu = unpack('<", indent, "", depth);
+    al = calign_add(al, offset);
+
+    size_t size = 0;
+    size_t i = 0;
+    for (; i < layout->fields.len && layout->fields.data[i].size != 0; i++) {
+        FieldAccessor fa = layout->fields.data[i];
+        assert(fa.type->kind == TypePrimitif, "Field accessor of non zero size doesn't point to primitive type");
+
+#define _case(x, f) \
+    case Primitif_##x: \
+        wt_format(s, f); \
+        wt_format(d, f); \
+        break
+        switch (fa.type->type.primitif) {
+            _case(u8, "B");
+            _case(u16, "H");
+            _case(u32, "I");
+            _case(u64, "Q");
+            _case(i8, "b");
+            _case(i16, "h");
+            _case(i32, "i");
+            _case(i64, "q");
+            _case(f32, "f");
+            _case(f64, "d");
+            _case(bool, "?");
+            _case(char, "c");
+        }
+#undef _case
+        al = calign_add(al, fa.size);
+        offset += fa.size;
+        size += fa.size;
+    }
+
+    size_t padding = 0;
+    if (i < layout->fields.len) {
+        padding = calign_to(al, layout->fields.data[i].type->align);
+        wt_format(s, "%lux", padding);
+    }
+
+    wt_format(s, "',\n");
+    wt_format(d, "', buf[off:off + %lu])\n", size);
+
+    for (size_t j = 0; j < i; j++) {
+        FieldAccessor fa = layout->fields.data[j];
+
+        wt_format(s, "%*s            ", indent, "");
+        write_field_accessor(s, base, fa, type, Read);
+        if (fa.type->kind == TypePrimitif && fa.type->type.primitif == Primitif_char) {
+            wt_format(s, ".encode(encoding='ASCII', errors='replace')");
+        }
+        if (j < i - 1) {
+            wt_format(s, ",\n");
+        } else {
+            wt_format(s, ")\n");
+        }
+
+        if (!field_accessor_is_array_length(fa, type)) {
+            wt_format(d, "%*s", indent, "");
+            write_field_accessor(d, base, fa, type, Write);
+            wt_format(d, " = xs%lu[%lu]", depth, j);
+            if (fa.type->kind == TypePrimitif && fa.type->type.primitif == Primitif_char) {
+                wt_format(d, ".decode(encoding='ASCII', errors='replace')");
+            }
+            wt_format(d, "\n");
+        }
+    }
+
+    if (i < layout->fields.len) {
+        wt_format(d, "%*soff += %lu\n", indent, "", padding + size);
+    } else {
+        wt_format(d, "%*soff += %lu\n", indent, "", padding + size + calign_to(al, align));
+    }
+
+    bool alignment_unknown = false;
+    for (; i < layout->fields.len; i++) {
+        alignment_unknown = true;
+
+        FieldAccessor fa = layout->fields.data[i];
+        uint64_t len_index = get_array_length_field_index(layout, fa);
+
+        if (fa.type->kind == TypePrimitif && fa.type->type.primitif == Primitif_char) {
+            wt_format(s, "%*sbuf += ", indent, "");
+            wt_format(d, "%*s", indent, "");
+            write_field_accessor(s, base, fa, type, Read);
+            write_field_accessor(d, base, fa, type, Write);
+
+            wt_format(d, " = buf[off:off + xs%lu[%lu]].decode(encoding='ASCII', errors='replace')\n", depth, len_index);
+            wt_format(d, "%*soff += xs%lu[%lu]\n", indent, "", depth, len_index);
+            wt_format(s, ".encode(encoding='ASCII', errors='replace')\n");
+            continue;
+        }
+
+        wt_format(s, "%*sfor e%lu in ", indent, "", depth);
+        write_field_accessor(s, base, fa, type, Read);
+        wt_format(s, ":\n");
+        wt_format(d, "%*s", indent, "");
+        write_field_accessor(d, base, fa, type, Write);
+        wt_format(d, " = []\n");
+        wt_format(d, "%*sfor _ in range(xs%lu[%lu]):\n", indent, "", depth, len_index);
+        if (fa.type->kind == TypeArray && fa.type->type.array.sizing == SizingFixed) {
+            wt_format(d, "%*se%lu = [None] * %lu\n", indent + INDENT, "", depth, fa.type->type.array.size);
+        } else if (fa.type->kind == TypeStruct) {
+            struct StructObject s = fa.type->type.struct_;
+            wt_format(d, "%*se%lu = %.*s.uninit()\n", indent + INDENT, "", depth, s.name.len, s.name.ptr);
+        }
+        char *new_base = msprintf("e%lu", depth);
+        write_type_funcs(
+            s,
+            d,
+            fa.type,
+            new_base,
+            (CurrentAlignment){.align = fa.type->align, .offset = 0},
+            layouts,
+            indent + INDENT,
+            depth + 1,
+            false
+        );
+        wt_format(d, "%*s", indent + INDENT, "");
+        write_field_accessor(d, base, fa, type, Write);
+        wt_format(d, ".append(%s)\n", new_base);
+        free(new_base);
+    }
+
+    if (alignment_unknown) {
+        wt_format(s, "%*sbuf += bytes((%u - len(buf)) & %u)\n", indent, "", align.value, align.mask);
+        wt_format(d, "%*soff += (%u - off) & %u\n", indent, "", align.value, align.mask);
+    }
+}
+
+static void write_struct_class(Writer *w, StructObject *obj, Hashmap *defined, Hashmap *layouts) {
+    TypeObject *type = (void *)((byte *)obj - offsetof(TypeObject, type));
+
+    wt_format(w, "@dataclass\n");
+    wt_format(w, "class %.*s:\n", obj->name.len, obj->name.ptr);
+    for (size_t i = 0; i < obj->fields.len; i++) {
+        Field f = obj->fields.data[i];
+        wt_format(w, "%*s%.*s: ", INDENT, "", f.name.len, f.name.ptr);
+        write_type_name(w, f.type, defined);
+        wt_format(w, "\n");
+    }
+    BufferedWriter ser = buffered_writer_init();
+    BufferedWriter deser = buffered_writer_init();
+    write_type_funcs(
+        (Writer *)&ser,
+        (Writer *)&deser,
+        type,
+        "self",
+        (CurrentAlignment){.align = type->align, .offset = 0},
+        layouts,
+        INDENT * 2,
+        0,
+        true
+    );
+
+    wt_format(w, "%*s\n", INDENT, "");
+    wt_format(w, "%*s@classmethod\n", INDENT, "");
+    wt_format(w, "%*sdef uninit(cls) -> '%.*s':\n", INDENT, "", obj->name.len, obj->name.ptr);
+    wt_format(w, "%*sself = cls.__new__(cls)\n", INDENT * 2, "");
+    write_type_uninit(w, type);
+    wt_format(w, "%*sreturn self\n", INDENT * 2, "");
+    wt_format(w, "%*s\n", INDENT, "");
+    wt_format(w, "%*sdef serialize(self, buf: bytearray):\n", INDENT, "");
+    wt_format(w, "%*sbase = len(buf)\n", INDENT * 2, "");
+    wt_write(w, ser.buf.data, ser.buf.len);
+    wt_format(w, "%*sreturn len(buf) - base\n", INDENT * 2, "");
+    wt_format(w, "%*s\n", INDENT, "");
+    wt_format(w, "%*sdef deserialize(self, buf: bytes):\n", INDENT, "");
+    wt_format(w, "%*soff = 0\n", INDENT * 2, "");
+    wt_write(w, deser.buf.data, deser.buf.len);
+    wt_format(w, "%*sreturn off\n", INDENT * 2, "");
+    wt_format(w, "\n");
+
+    buffered_writer_drop(ser);
+    buffered_writer_drop(deser);
+
+    hashmap_set(defined, &obj);
+}
+
+typedef struct {
+    Hashmap *layouts;
+    Hashmap *defined;
+} CallbackData;
+
+static void write_struct(Writer *w, StructObject *obj, void *user_data) {
+    CallbackData *data = user_data;
+    write_struct_class(w, obj, data->defined, data->layouts);
+}
+
+static void define_struct_classes(Writer *w, Program *p) {
+    Hashmap *defined = hashmap_init(pointer_hash, pointer_equal, NULL, sizeof(StructObject *));
+    CallbackData data = {.defined = defined, .layouts = p->layouts};
+    define_structs(p, w, write_struct, &data);
+    hashmap_drop(defined);
+}
+
+static void define_message(Writer *w, const char *prefix, uint16_t tag, Hashmap *layouts, MessageObject msg, uint64_t version) {
+    char *name = msprintf("%s%.*s", prefix, msg.name.len, msg.name.ptr);
+    StringSlice name_slice = {.ptr = name, .len = strlen(name)};
+
+    wt_format(w, "@dataclass\n");
+    wt_format(w, "class %s(%sMessage):\n", name, prefix);
+
+    TypeObject *type;
+    StructObject *obj;
+    FieldVec fields = vec_clone(&msg.fields);
+    {
+        if (msg.attributes & Attr_versioned) {
+            Field f = {.name = STRING_SLICE("_version"), .type = (TypeObject *)&PRIMITIF_u64};
+            vec_push(&fields, f);
+        }
+
+        type = malloc(sizeof(TypeObject));
+        assert_alloc(type);
+        type->kind = TypeStruct;
+        type->type.struct_.name = name_slice;
+        type->type.struct_.has_funcs = false;
+        type->type.struct_.fields = *(AnyVec *)&fields;
+        type->align = ALIGN_8;
+        obj = (StructObject *)&type->type.struct_;
+
+        Layout l = type_layout(type);
+        hashmap_set(layouts, &l);
+    }
+
+    for (size_t i = 0; i < msg.fields.len; i++) {
+        Field f = msg.fields.data[i];
+        wt_format(w, "%*s%.*s: ", INDENT, "", f.name.len, f.name.ptr);
+        write_type_name(w, f.type, NULL);
+        wt_format(w, "\n");
+    }
+
+    if (msg.attributes & Attr_versioned) {
+        wt_format(w, "%*s_version: int = %lu\n", INDENT, "", version);
+    }
+
+    BufferedWriter ser = buffered_writer_init();
+    BufferedWriter deser = buffered_writer_init();
+    write_type_funcs(
+        (Writer *)&ser,
+        (Writer *)&deser,
+        type,
+        "self",
+        (CurrentAlignment){.align = type->align, .offset = 2},
+        layouts,
+        INDENT * 2,
+        0,
+        true
+    );
+
+    wt_format(w, "%*s\n", INDENT, "");
+    wt_format(w, "%*s@classmethod\n", INDENT, "");
+    wt_format(w, "%*sdef uninit(cls) -> '%s':\n", INDENT, "", name);
+    wt_format(w, "%*sself = cls.__new__(cls)\n", INDENT * 2, "");
+    write_type_uninit(w, type);
+    wt_format(w, "%*sreturn self\n", INDENT * 2, "");
+    wt_format(w, "%*s\n", INDENT, "");
+    wt_format(w, "%*sdef serialize(self, buf: bytearray):\n", INDENT, "");
+    wt_format(w, "%*sbase = len(buf)\n", INDENT * 2, "");
+    wt_format(w, "%*sbuf += pack('>QH', MSG_MAGIC_START, %u)\n", INDENT * 2, "", tag);
+    wt_write(w, ser.buf.data, ser.buf.len);
+    wt_format(w, "%*sbuf += pack('>Q', MSG_MAGIC_END)\n", INDENT * 2, "");
+    wt_format(w, "%*sreturn len(buf) - base\n", INDENT * 2, "");
+    wt_format(w, "%*s\n", INDENT, "");
+    wt_format(w, "%*s@classmethod\n", INDENT, "");
+    wt_format(w, "%*sdef _deserialize(cls, buf: bytes) -> Tuple['%s', int]:\n", INDENT, "", name);
+    wt_format(w, "%*smagic_start, tag = unpack('>QH', buf[0:10])\n", INDENT * 2, "");
+    wt_format(w, "%*sif magic_start != MSG_MAGIC_START or tag != %u:\n", INDENT * 2, "", tag);
+    wt_format(w, "%*sraise ValueError\n", INDENT * 3, "");
+    wt_format(w, "%*soff = 10\n", INDENT * 2, "");
+    wt_format(w, "%*sself = %s.uninit()\n", INDENT * 2, "", name);
+    wt_write(w, deser.buf.data, deser.buf.len);
+    wt_format(w, "%*smagic_end = unpack('>Q', buf[off:off + 8])[0]\n", INDENT * 2, "");
+    wt_format(w, "%*sif magic_end != MSG_MAGIC_END:\n", INDENT * 2, "");
+    wt_format(w, "%*sraise ValueError\n", INDENT * 3, "");
+    wt_format(w, "%*soff += 8\n", INDENT * 2, "");
+    wt_format(w, "%*sreturn self, off\n", INDENT * 2, "");
+    wt_format(w, "\n");
+
+    buffered_writer_drop(ser);
+    buffered_writer_drop(deser);
+    free(name);
+    vec_drop(fields);
+    free(type);
+}
+
+static void define_messages(Writer *w, MessagesObject msgs, Program *p) {
+    char *prefix = strndup(msgs.name.ptr, msgs.name.len);
+    wt_format(w, "class %sMessage(ABC):\n", prefix);
+    wt_format(w, "%*s@abstractmethod\n", INDENT, "");
+    wt_format(w, "%*sdef serialize(self, buf: bytearray) -> int:\n", INDENT, "");
+    wt_format(w, "%*spass\n", INDENT * 2, "");
+    wt_format(w, "%*s@classmethod\n", INDENT, "");
+    wt_format(w, "%*sdef deserialize(cls, buf: bytes) -> Tuple['Message', int]:\n", INDENT, "");
+    wt_format(w, "%*smagic_start, tag = unpack('>QH', buf[0:10])\n", INDENT * 2, "");
+    wt_format(w, "%*sif magic_start != MSG_MAGIC_START:\n", INDENT * 2, "");
+    wt_format(w, "%*sraise ValueError\n", INDENT * 3, "");
+    for (size_t i = 0; i < msgs.messages.len; i++) {
+        if (i == 0) {
+            wt_format(w, "%*sif tag == 0:\n", INDENT * 2, "");
+        } else {
+            wt_format(w, "%*selif tag == %lu:\n", INDENT * 2, "", i);
+        }
+        StringSlice name = msgs.messages.data[i].name;
+        wt_format(w, "%*sreturn %s%.*s._deserialize(buf)\n", INDENT * 3, "", prefix, name.len, name.ptr);
+    }
+    wt_format(w, "%*selse:\n", INDENT * 2, "");
+    wt_format(w, "%*sraise ValueError\n", INDENT * 3, "");
+
+    for (size_t i = 0; i < msgs.messages.len; i++) {
+        define_message(w, prefix, i, p->layouts, msgs.messages.data[i], msgs.version);
+    }
+    free(prefix);
+}
+
+void codegen_python(Writer *source, Program *p) {
+    wt_format(
+        source,
+        "# generated file\n"
+        "from dataclasses import dataclass\n"
+        "from typing import List, Tuple\n"
+        "from abc import ABC, abstractmethod\n"
+        "from struct import pack, unpack\n"
+        "\n"
+        "MSG_MAGIC_START = 0x%016lX\n"
+        "MSG_MAGIC_END = 0x%016lX\n"
+        "\n",
+        MSG_MAGIC_START,
+        MSG_MAGIC_END
+    );
+
+    define_struct_classes(source, p);
+    for (size_t i = 0; i < p->messages.len; i++) {
+        define_messages(source, p->messages.data[i], p);
+    }
+}

ser/codegen_python.h

@@ -0,0 +1,8 @@
+#ifndef CODEGEN_PYTHON_H
+#define CODEGEN_PYTHON_H
+
+#include "codegen.h"
+
+void codegen_python(Writer *source, Program *p);
+
+#endif

ser/macro_utils.h

@@ -22,6 +22,7 @@
 #define SND(a, b, ...) b
 #define FST(a, ...) a
 #define CAT(a, b) a##b
+#define STR(a) #a
 
 #define PROBE() ~, 1
 #define IS_PROBE(...) SND(__VA_ARGS__, 0)

ser/main.c

@@ -1,5 +1,6 @@
 #include "ast.h"
 #include "codegen_c.h"
+#include "codegen_python.h"
 #include "hashmap.h"
 #include "lexer.h"
 #include "log.h"
@@ -16,15 +17,31 @@ void abort_error(uint32_t error_count) {
 
 typedef enum {
     BackendC,
+    BackendPython,
 } Backend;
 
+static Hashmap *backend_map = NULL;
+
+typedef struct {
+    StringSlice name;
+    Backend b;
+} BackendString;
+
+impl_hashmap_delegate(backend, BackendString, string_slice, name);
+
 Backend parse_backend(const char *b) {
-    if (strcmp(b, "c") == 0) {
+    if (backend_map == NULL) {
-        return BackendC;
+        backend_map = hashmap_init(backend_hash, backend_equal, NULL, sizeof(BackendString));
-    } else {
+        hashmap_set(backend_map, &(BackendString){.name = STRING_SLICE("c"), .b = BackendC});
-        log_error("Couldn't parse requested backend: got %s expected one of 'c'.", b);
+        hashmap_set(backend_map, &(BackendString){.name = STRING_SLICE("python"), .b = BackendPython});
+    }
+
+    BackendString *backend = hashmap_get(backend_map, &(BackendString){.name.ptr = b, .name.len = strlen(b)});
+    if (backend == NULL) {
+        log_error("Unknown backend '%s'", b);
         exit(1);
     }
+    return backend->b;
 }
 
 int main(int argc, char **argv) {
@@ -102,10 +119,25 @@ int main(int argc, char **argv) {
         free(header_path);
         break;
     }
+    case BackendPython: {
+        FileWriter source = file_writer_init(output);
+
+        codegen_python((Writer *)&source, &evaluation_result.program);
+
+        file_writer_drop(source);
+        break;
+    }
+    default:
+        log_error("What the fuck ?");
+        exit(1);
     }
 
     program_drop(evaluation_result.program);
     ast_drop(parsing_result.ctx);
     vec_drop(lexing_result.tokens);
     source_drop(src);
+
+    if (backend_map != NULL) {
+        hashmap_drop(backend_map);
+    }
 }