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#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "vm.h"
#include "ast.h"
#include "read.h"
#include "state.h"
static size_t placeholder(State *S, Chunk *ch) {
size_t old_ix = ch->bc.len;
chunk_wbc(S, ch, 0x00);
chunk_wbc(S, ch, 0x00);
return old_ix;
}
static void patch(State *S, Chunk *ch, size_t addr, uint16_t val) {
ch->bc.d[addr] = val & 0xff;
ch->bc.d[addr+1] = (val & 0xff00) >> 8;
}
static void compile_node(State *S, Chunk *ch, AstNode a);
typedef void (*form_compiler)(State *S, Chunk *ch, AstVec l, Op op);
typedef struct {
char *name;
int min_params;
bool ellipsis;
form_compiler action;
Op op;
} BuiltinForm;
void single_form(State *S, Chunk *ch, AstVec l, Op op) {
compile_node(S, ch, l.vals[1]);
chunk_wbc(S, ch, op);
}
void set_form(State *S, Chunk *ch, AstVec l, Op op) {
AstNode ident = l.vals[1];
if (ident.ty != AST_IDENT) {
fprintf(stderr, "set's first argument must be identifier");
exit(1);
}
ObjString *o = objstring_copy_cstr(S, ident.as.str);
compile_node(S, ch, l.vals[2]);
chunk_wbc(S, ch, OP_SETGLOBAL);
chunk_wbc(S, ch, chunk_wconst(S, ch, VAL_OBJ(o)));
}
void do_form(State *S, Chunk *ch, AstVec l, Op op) {
for (int i = 1; i < l.len - 1; i++) {
compile_node(S, ch, l.vals[i]);
chunk_wbc(S, ch, OP_DROP);
}
compile_node(S, ch, l.vals[l.len - 1]);
}
void if_form(State *S, Chunk *ch, AstVec l, Op op) {
// (if cond if-true if-false)
// cond
// 0branch ->A
// if-true
// skip ->B
// A: if-false
// B:
compile_node(S, ch, l.vals[1]);
chunk_wbc(S, ch, OP_0BRANCH);
size_t ph_a = placeholder(S, ch);
compile_node(S, ch, l.vals[2]);
chunk_wbc(S, ch, OP_SKIP);
size_t ph_b = placeholder(S, ch);
size_t dest_a = ch->bc.len;
compile_node(S, ch, l.vals[3]);
size_t dest_b = ch->bc.len;
patch(S, ch, ph_a, dest_a - ph_a - 2);
patch(S, ch, ph_b, dest_b - ph_b - 2);
}
void while_form(State *S, Chunk *ch, AstVec l, Op op) {
// (while cond body ...)
// A:
// cond
// 0branch ->B
// body ....
// redo ->A
// B:
// nil (while loop always returns nil)
size_t dest_a = ch->bc.len;
compile_node(S, ch, l.vals[1]);
chunk_wbc(S, ch, OP_0BRANCH);
size_t ph_b = placeholder(S, ch);
for (int i = 2; i < l.len; i++) {
compile_node(S, ch, l.vals[i]);
chunk_wbc(S, ch, OP_DROP);
}
chunk_wbc(S, ch, OP_REDO);
size_t ph_a = placeholder(S, ch);
size_t dest_b = ch->bc.len;
chunk_wbc(S, ch, OP_NIL);
patch(S, ch, ph_a, ph_a - dest_a + 2);
patch(S, ch, ph_b, dest_b - ph_b - 2);
}
void arith_form(State *S, Chunk *ch, AstVec l, Op op) {
compile_node(S, ch, l.vals[1]);
compile_node(S, ch, l.vals[2]);
chunk_wbc(S, ch, op);
}
static BuiltinForm builtin_forms[] = {
{ "puts", 1, false, single_form, OP_PUTS },
{ "print", 1, false, single_form, OP_PRINT },
{ "set", 2, false, set_form, 0 },
{ "do", 1, true, do_form, 0 },
{ "if", 3, false, if_form, 0 },
{ "while", 2, true, while_form, 0 },
#define ARITH_OP(str, op) \
{ str, 2, false, arith_form, op },
ARITH_OP("+", OP_ADD)
ARITH_OP("-", OP_SUB)
ARITH_OP("*", OP_MUL)
ARITH_OP("/", OP_DIV)
ARITH_OP("=", OP_EQU)
ARITH_OP("<", OP_CMP)
ARITH_OP("%", OP_MOD)
#undef ARITH_OP
{ 0 },
};
typedef struct {
char *name;
Op op;
} BuiltinIdent;
static BuiltinIdent builtin_idents[] = {
{ "true", OP_TRUE },
{ "false", OP_FALSE },
{ "nil", OP_NIL },
{ 0 },
};
static void compile_node(State *S, Chunk *ch, AstNode a) {
switch (a.ty) {
case AST_IDENT:;
char *ident = a.as.str;
BuiltinIdent *found_builtin = NULL;
for (BuiltinIdent *b = builtin_idents; b->name != NULL; b++) {
if (0 == strcmp(b->name, ident)) {
found_builtin = b;
break;
}
}
if (found_builtin != NULL) {
chunk_wbc(S, ch, found_builtin->op);
} else {
// read global variable
ObjString *o = objstring_copy_cstr(S, a.as.str);
chunk_wbc(S, ch, OP_GETGLOBAL);
chunk_wbc(S, ch, chunk_wconst(S, ch, VAL_OBJ(o)));
}
break;
case AST_NUM:
chunk_wbc(S, ch, OP_LOADK);
chunk_wbc(S, ch, chunk_wconst(S, ch, VAL_NUM(a.as.num)));
break;
case AST_STRING: {
ObjString *o = objstring_copy_cstr(S, a.as.str);
chunk_wbc(S, ch, OP_LOADK);
chunk_wbc(S, ch, chunk_wconst(S, ch, VAL_OBJ(o)));
break;
}
case AST_LIST: {
AstVec l = a.as.list;
#define CK(cond, msg) if (!(cond)) { fputs(msg "\n", stderr); exit(1); }
CK(l.len > 0, "can't handle empty list");
CK(l.vals[0].ty == AST_IDENT, "can only call ops");
char *head = l.vals[0].as.str;
BuiltinForm *form = NULL;
for (BuiltinForm *b = builtin_forms; b->name != NULL; b++) {
if (0 == strcmp(b->name, head)) {
form = b;
break;
}
}
if (form != NULL) {
if (form->ellipsis && l.len < form->min_params + 1) {
fprintf(stderr, "%s requires at least %d parameters\n",
form->name, form->min_params);
exit(1);
} else if (!form->ellipsis && l.len != form->min_params + 1) {
fprintf(stderr, "%s requires exactly %d parameters\n",
form->name, form->min_params);
exit(1);
}
form->action(S, ch, l, form->op);
} else {
fprintf(stderr, "unknown form %s\n", head);
exit(1);
}
break;
}
}
}
int main(int argc, char **argv) {
State st = state_new();
State *S = &st;
Thread th = thread_new(S);
st.th = &th;
Chunk ch = chunk_new(S);
th.ch = &ch;
S->do_disasm = (argc > 1 && 0 == strcmp(argv[1], "-l"));
char n1[] = "foo";
char n2[] = "bar";
char n3[] = "baz";
ObjString *o1 = objstring_copy_cstr(S, n1);
ObjString *o2 = objstring_copy_cstr(S, n2);
ObjString *o3 = objstring_copy_cstr(S, n3);
ht_put(S, &st.globals, o1, VAL_NUM(69));
ht_put(S, &st.globals, o2, VAL_NUM(2));
ht_put(S, &st.globals, o3, VAL_NUM(3));
AstNode an = read();
compile_node(S, &ch, an);
chunk_wbc(S, &ch, OP_PUTS);
chunk_wbc(S, &ch, OP_RET);
return runvm(S);
}
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