Ejemplo n.º 1
0
Archivo: jv_parse.c Proyecto: dfkoh/jq
jv jv_parser_next(struct jv_parser* p) {
  assert(p->curr_buf && "a buffer must be provided");
  if (p->bom_strip_position == 0xff) return jv_invalid_with_msg(jv_string("Malformed BOM"));
  jv value;
  presult msg = 0;
  while (!msg && p->curr_buf_pos < p->curr_buf_length) {
    char ch = p->curr_buf[p->curr_buf_pos++];
    msg = scan(p, ch, &value);
  }
  if (msg == OK) {
    return value;
  } else if (msg) {
    return jv_invalid_with_msg(jv_string_fmt("%s at line %d, column %d", msg, p->line, p->column));
  } else if (p->curr_buf_is_partial) {
    assert(p->curr_buf_pos == p->curr_buf_length);
    // need another buffer
    return jv_invalid();
  } else {
    assert(p->curr_buf_pos == p->curr_buf_length);
    // at EOF
    if (p->st != JV_PARSER_NORMAL) 
      return jv_invalid_with_msg(jv_string("Unfinished string"));
    if ((msg = check_literal(p)))
      return jv_invalid_with_msg(jv_string(msg));
    if (p->stackpos != 0)
      return jv_invalid_with_msg(jv_string("Unfinished JSON term"));
    // p->next is either invalid (nothing here but no syntax error)
    // or valid (this is the value). either way it's the thing to return
    value = p->next;
    p->next = jv_invalid();
    return value;
  }
}
Ejemplo n.º 2
0
Archivo: jv_parse.c Proyecto: dfkoh/jq
static int check_done(struct jv_parser* p, jv* out) {
  if (p->stackpos == 0 && jv_is_valid(p->next)) {
    *out = p->next;
    p->next = jv_invalid();
    return 1;
  } else {
    return 0;
  }
}
Ejemplo n.º 3
0
Archivo: locfile.c Proyecto: 4honor/jq
void locfile_locate(struct locfile* l, location loc, const char* fmt, ...) {
  jq_err_cb cb;
  void *cb_data;
  va_list fmtargs;
  va_start(fmtargs, fmt);
  int startline;
  int offset;

  if (loc.start != -1) {
    startline = locfile_get_line(l, loc.start);
    offset = l->linemap[startline];
  }

  jq_get_error_cb(l->jq, &cb, &cb_data);

  jv m1 = jv_string_vfmt(fmt, fmtargs);
  if (!jv_is_valid(m1)) {
    jv_free(m1);
    goto enomem;
  }
  jv m2;
  if (loc.start == -1) {
    m2 = jv_string_fmt("%s\n<unknown location>", jv_string_value(m1));
    if (cb)
      cb(cb_data, m2);
    else
      fprintf(stderr, "%s", jv_string_value(m2));
    jv_free(m1);
    jv_free(m2);
    return;
  }
  m2 = jv_string_fmt("%s\n%.*s%*s", jv_string_value(m1),
                     locfile_line_length(l, startline), l->data + offset,
                     loc.start - offset, "");
  jv_free(m1);
  if (!jv_is_valid(m2)) {
    jv_free(m2);
    goto enomem;
  }
  if (cb)
    cb(cb_data, m2);
  else
    fprintf(stderr, "%s", jv_string_value(m2));
  jv_free(m2);
  return;

enomem:
  if (cb != NULL)
    cb(cb_data, jv_invalid());
  else if (errno == ENOMEM || errno == 0)
    fprintf(stderr, "Error formatting jq compilation error: %s", strerror(errno ? errno : ENOMEM));
  else
    fprintf(stderr, "Error formatting jq compilation error: %s", strerror(errno));
  return;
}
Ejemplo n.º 4
0
Archivo: jv.c Proyecto: fblondiau/jq
jv jv_array_get(jv j, int idx) {
  assert(jv_get_kind(j) == JV_KIND_ARRAY);
  jv* slot = jvp_array_read(j, idx);
  jv val;
  if (slot) {
    val = jv_copy(*slot);
  } else {
    val = jv_invalid();
  }
  jv_free(j);
  return val;
}
Ejemplo n.º 5
0
Archivo: jv_parse.c Proyecto: dfkoh/jq
static void parser_init(struct jv_parser* p) {
  p->stack = 0;
  p->stacklen = p->stackpos = 0;
  p->next = jv_invalid();
  p->tokenbuf = 0;
  p->tokenlen = p->tokenpos = 0;
  p->st = JV_PARSER_NORMAL;
  p->curr_buf = 0;
  p->curr_buf_length = p->curr_buf_pos = p->curr_buf_is_partial = 0;
  p->bom_strip_position = 0;
  p->line = 1;
  p->column = 0;
  jvp_dtoa_context_init(&p->dtoa);
}
Ejemplo n.º 6
0
static struct frame* frame_push(struct jq_state* jq, struct closure callee, 
                                uint16_t* argdef, int nargs) {
  stack_ptr new_frame_idx = stack_push_block(&jq->stk, jq->curr_frame, frame_size(callee.bc));
  struct frame* new_frame = stack_block(&jq->stk, new_frame_idx);
  new_frame->bc = callee.bc;
  new_frame->env = callee.env;
  assert(nargs == new_frame->bc->nclosures);
  union frame_entry* entries = new_frame->entries;
  int i;
  for (i=0; i<nargs; i++) {
    entries->closure = make_closure(jq, argdef + i * 2);
    entries++;
  }
  for (i=0; i<callee.bc->nlocals; i++) {
    entries->localvar = jv_invalid();
    entries++;
  }
  jq->curr_frame = new_frame_idx;
  return new_frame;
}
Ejemplo n.º 7
0
Archivo: jv_parse.c Proyecto: dfkoh/jq
static pfunc token(struct jv_parser* p, char ch) {
  switch (ch) {
  case '[':
    if (jv_is_valid(p->next)) return "Expected separator between values";
    push(p, jv_array());
    break;

  case '{':
    if (jv_is_valid(p->next)) return "Expected separator between values";
    push(p, jv_object());
    break;

  case ':':
    if (!jv_is_valid(p->next)) 
      return "Expected string key before ':'";
    if (p->stackpos == 0 || jv_get_kind(p->stack[p->stackpos-1]) != JV_KIND_OBJECT)
      return "':' not as part of an object";
    if (jv_get_kind(p->next) != JV_KIND_STRING)
      return "Object keys must be strings";
    push(p, p->next);
    p->next = jv_invalid();
    break;

  case ',':
    if (!jv_is_valid(p->next))
      return "Expected value before ','";
    if (p->stackpos == 0)
      return "',' not as part of an object or array";
    if (jv_get_kind(p->stack[p->stackpos-1]) == JV_KIND_ARRAY) {
      p->stack[p->stackpos-1] = jv_array_append(p->stack[p->stackpos-1], p->next);
      p->next = jv_invalid();
    } else if (jv_get_kind(p->stack[p->stackpos-1]) == JV_KIND_STRING) {
      assert(p->stackpos > 1 && jv_get_kind(p->stack[p->stackpos-2]) == JV_KIND_OBJECT);
      p->stack[p->stackpos-2] = jv_object_set(p->stack[p->stackpos-2], 
                                              p->stack[p->stackpos-1], p->next);
      p->stackpos--;
      p->next = jv_invalid();
    } else {
      // this case hits on input like {"a", "b"}
      return "Objects must consist of key:value pairs";
    }
    break;

  case ']':
    if (p->stackpos == 0 || jv_get_kind(p->stack[p->stackpos-1]) != JV_KIND_ARRAY)
      return "Unmatched ']'";
    if (jv_is_valid(p->next)) {
      p->stack[p->stackpos-1] = jv_array_append(p->stack[p->stackpos-1], p->next);
      p->next = jv_invalid();
    } else {
      if (jv_array_length(jv_copy(p->stack[p->stackpos-1])) != 0) {
        // this case hits on input like [1,2,3,]
        return "Expected another array element";
      }
    }
    jv_free(p->next);
    p->next = p->stack[--p->stackpos];
    break;

  case '}':
    if (p->stackpos == 0)
      return "Unmatched '}'";
    if (jv_is_valid(p->next)) {
      if (jv_get_kind(p->stack[p->stackpos-1]) != JV_KIND_STRING)
        return "Objects must consist of key:value pairs";
      assert(p->stackpos > 1 && jv_get_kind(p->stack[p->stackpos-2]) == JV_KIND_OBJECT);
      p->stack[p->stackpos-2] = jv_object_set(p->stack[p->stackpos-2], 
                                              p->stack[p->stackpos-1], p->next);
      p->stackpos--;
      p->next = jv_invalid();
    } else {
      if (jv_get_kind(p->stack[p->stackpos-1]) != JV_KIND_OBJECT)
        return "Unmatched '}'";
      if (jv_object_length(jv_copy(p->stack[p->stackpos-1])) != 0)
        return "Expected another key-value pair";
    }
    jv_free(p->next);
    p->next = p->stack[--p->stackpos];
    break;
  }
  return 0;
}
Ejemplo n.º 8
0
jv jq_next(jq_state *jq) {
  jv cfunc_input[MAX_CFUNCTION_ARGS];

  jv_nomem_handler(jq->nomem_handler, jq->nomem_handler_data);

  uint16_t* pc = stack_restore(jq);
  assert(pc);

  int backtracking = !jq->initial_execution;
  jq->initial_execution = 0;
  while (1) {
    uint16_t opcode = *pc;

    if (jq->debug_trace_enabled) {
      dump_operation(frame_current(jq)->bc, pc);
      printf("\t");
      const struct opcode_description* opdesc = opcode_describe(opcode);
      stack_ptr param = 0;
      if (!backtracking) {
        int stack_in = opdesc->stack_in;
        if (stack_in == -1) stack_in = pc[1];
        int i;
        for (i=0; i<stack_in; i++) {
          if (i == 0) {
            param = jq->stk_top;
          } else {
            printf(" | ");
            param = *stack_block_next(&jq->stk, param);
          }
          if (!param) break;
          jv_dump(jv_copy(*(jv*)stack_block(&jq->stk, param)), 0);
          //printf("<%d>", jv_get_refcnt(param->val));
          //printf(" -- ");
          //jv_dump(jv_copy(jq->path), 0);
        }
      } else {
        printf("\t<backtracking>");
      }

      printf("\n");
    }

    if (backtracking) {
      opcode = ON_BACKTRACK(opcode);
      backtracking = 0;
    }
    pc++;

    switch (opcode) {
    default: assert(0 && "invalid instruction");

    case LOADK: {
      jv v = jv_array_get(jv_copy(frame_current(jq)->bc->constants), *pc++);
      assert(jv_is_valid(v));
      jv_free(stack_pop(jq));
      stack_push(jq, v);
      break;
    }

    case DUP: {
      jv v = stack_pop(jq);
      stack_push(jq, jv_copy(v));
      stack_push(jq, v);
      break;
    }

    case DUP2: {
      jv keep = stack_pop(jq);
      jv v = stack_pop(jq);
      stack_push(jq, jv_copy(v));
      stack_push(jq, keep);
      stack_push(jq, v);
      break;
    }

    case SUBEXP_BEGIN: {
      jv v = stack_pop(jq);
      stack_push(jq, jv_copy(v));
      stack_push(jq, v);
      jq->subexp_nest++;
      break;
    }

    case SUBEXP_END: {
      assert(jq->subexp_nest > 0);
      jq->subexp_nest--;
      jv a = stack_pop(jq);
      jv b = stack_pop(jq);
      stack_push(jq, a);
      stack_push(jq, b);
      break;
    }
      
    case POP: {
      jv_free(stack_pop(jq));
      break;
    }

    case APPEND: {
      jv v = stack_pop(jq);
      uint16_t level = *pc++;
      uint16_t vidx = *pc++;
      jv* var = frame_local_var(jq, vidx, level);
      assert(jv_get_kind(*var) == JV_KIND_ARRAY);
      *var = jv_array_append(*var, v);
      break;
    }

    case INSERT: {
      jv stktop = stack_pop(jq);
      jv v = stack_pop(jq);
      jv k = stack_pop(jq);
      jv objv = stack_pop(jq);
      assert(jv_get_kind(objv) == JV_KIND_OBJECT);
      if (jv_get_kind(k) == JV_KIND_STRING) {
        stack_push(jq, jv_object_set(objv, k, v));
        stack_push(jq, stktop);
      } else {
        print_error(jq, jv_invalid_with_msg(jv_string_fmt("Cannot use %s as object key",
                                                          jv_kind_name(jv_get_kind(k)))));
        jv_free(stktop);
        jv_free(v);
        jv_free(k);
        jv_free(objv);
        goto do_backtrack;
      }
      break;
    }

    case ON_BACKTRACK(RANGE):
    case RANGE: {
      uint16_t level = *pc++;
      uint16_t v = *pc++;
      jv* var = frame_local_var(jq, v, level);
      jv max = stack_pop(jq);
      if (jv_get_kind(*var) != JV_KIND_NUMBER ||
          jv_get_kind(max) != JV_KIND_NUMBER) {
        print_error(jq, jv_invalid_with_msg(jv_string_fmt("Range bounds must be numeric")));
        jv_free(max);
        goto do_backtrack;
      } else if (jv_number_value(jv_copy(*var)) >= jv_number_value(jv_copy(max))) {
        /* finished iterating */
        goto do_backtrack;
      } else {
        jv curr = jv_copy(*var);
        *var = jv_number(jv_number_value(*var) + 1);

        struct stack_pos spos = stack_get_pos(jq);
        stack_push(jq, jv_copy(max));
        stack_save(jq, pc - 3, spos);

        stack_push(jq, curr);
      }
      break;
    }

      // FIXME: loadv/storev may do too much copying/freeing
    case LOADV: {
      uint16_t level = *pc++;
      uint16_t v = *pc++;
      jv* var = frame_local_var(jq, v, level);
      if (jq->debug_trace_enabled) {
        printf("V%d = ", v);
        jv_dump(jv_copy(*var), 0);
        printf("\n");
      }
      jv_free(stack_pop(jq));
      stack_push(jq, jv_copy(*var));
      break;
    }

      // Does a load but replaces the variable with null
    case LOADVN: {
      uint16_t level = *pc++;
      uint16_t v = *pc++;
      jv* var = frame_local_var(jq, v, level);
      if (jq->debug_trace_enabled) {
        printf("V%d = ", v);
        jv_dump(jv_copy(*var), 0);
        printf("\n");
      }
      jv_free(stack_pop(jq));
      stack_push(jq, *var);
      *var = jv_null();
      break;
    }

    case STOREV: {
      uint16_t level = *pc++;
      uint16_t v = *pc++;
      jv* var = frame_local_var(jq, v, level);
      jv val = stack_pop(jq);
      if (jq->debug_trace_enabled) {
        printf("V%d = ", v);
        jv_dump(jv_copy(val), 0);
        printf("\n");
      }
      jv_free(*var);
      *var = val;
      break;
    }

    case PATH_BEGIN: {
      jv v = stack_pop(jq);
      stack_push(jq, jq->path);

      stack_save(jq, pc - 1, stack_get_pos(jq));

      stack_push(jq, jv_number(jq->subexp_nest));
      stack_push(jq, v);

      jq->path = jv_array();
      jq->subexp_nest = 0;
      break;
    }

    case PATH_END: {
      jv v = stack_pop(jq);
      jv_free(v); // discard value, only keep path

      int old_subexp_nest = (int)jv_number_value(stack_pop(jq));

      jv path = jq->path;
      jq->path = stack_pop(jq);

      struct stack_pos spos = stack_get_pos(jq);
      stack_push(jq, jv_copy(path));
      stack_save(jq, pc - 1, spos);

      stack_push(jq, path);
      jq->subexp_nest = old_subexp_nest;
      break;
    }

    case ON_BACKTRACK(PATH_BEGIN):
    case ON_BACKTRACK(PATH_END): {
      jv_free(jq->path);
      jq->path = stack_pop(jq);
      goto do_backtrack;
    }

    case INDEX:
    case INDEX_OPT: {
      jv t = stack_pop(jq);
      jv k = stack_pop(jq);
      path_append(jq, jv_copy(k));
      jv v = jv_get(t, k);
      if (jv_is_valid(v)) {
        stack_push(jq, v);
      } else {
        if (opcode == INDEX)
          print_error(jq, v);
        else
          jv_free(v);
        goto do_backtrack;
      }
      break;
    }


    case JUMP: {
      uint16_t offset = *pc++;
      pc += offset;
      break;
    }

    case JUMP_F: {
      uint16_t offset = *pc++;
      jv t = stack_pop(jq);
      jv_kind kind = jv_get_kind(t);
      if (kind == JV_KIND_FALSE || kind == JV_KIND_NULL) {
        pc += offset;
      }
      stack_push(jq, t); // FIXME do this better
      break;
    }

    case EACH: 
    case EACH_OPT: 
      stack_push(jq, jv_number(-1));
      // fallthrough
    case ON_BACKTRACK(EACH):
    case ON_BACKTRACK(EACH_OPT): {
      int idx = jv_number_value(stack_pop(jq));
      jv container = stack_pop(jq);

      int keep_going, is_last = 0;
      jv key, value;
      if (jv_get_kind(container) == JV_KIND_ARRAY) {
        if (opcode == EACH || opcode == EACH_OPT) idx = 0;
        else idx = idx + 1;
        int len = jv_array_length(jv_copy(container));
        keep_going = idx < len;
        is_last = idx == len - 1;
        if (keep_going) {
          key = jv_number(idx);
          value = jv_array_get(jv_copy(container), idx);
        }
      } else if (jv_get_kind(container) == JV_KIND_OBJECT) {
        if (opcode == EACH || opcode == EACH_OPT) idx = jv_object_iter(container);
        else idx = jv_object_iter_next(container, idx);
        keep_going = jv_object_iter_valid(container, idx);
        if (keep_going) {
          key = jv_object_iter_key(container, idx);
          value = jv_object_iter_value(container, idx);
        }
      } else {
        assert(opcode == EACH || opcode == EACH_OPT);
        if (opcode == EACH) {
          print_error(jq,
                      jv_invalid_with_msg(jv_string_fmt("Cannot iterate over %s",
                                                        jv_kind_name(jv_get_kind(container)))));
        }
        keep_going = 0;
      }

      if (!keep_going) {
        jv_free(container);
        goto do_backtrack;
      } else if (is_last) {
        // we don't need to make a backtrack point
        jv_free(container);
        path_append(jq, key);
        stack_push(jq, value);
      } else {
        struct stack_pos spos = stack_get_pos(jq);
        stack_push(jq, container);
        stack_push(jq, jv_number(idx));
        stack_save(jq, pc - 1, spos);
        path_append(jq, key);
        stack_push(jq, value);
      }
      break;
    }

    do_backtrack:
    case BACKTRACK: {
      pc = stack_restore(jq);
      if (!pc) {
        return jv_invalid();
      }
      backtracking = 1;
      break;
    }

    case FORK: {
      stack_save(jq, pc - 1, stack_get_pos(jq));
      pc++; // skip offset this time
      break;
    }

    case ON_BACKTRACK(FORK): {
      uint16_t offset = *pc++;
      pc += offset;
      break;
    }
      
    case CALL_BUILTIN: {
      int nargs = *pc++;
      jv top = stack_pop(jq);
      jv* in = cfunc_input;
      int i;
      in[0] = top;
      for (i = 1; i < nargs; i++) {
        in[i] = stack_pop(jq);
      }
      struct cfunction* function = &frame_current(jq)->bc->globals->cfunctions[*pc++];
      typedef jv (*func_1)(jv);
      typedef jv (*func_2)(jv,jv);
      typedef jv (*func_3)(jv,jv,jv);
      typedef jv (*func_4)(jv,jv,jv,jv);
      typedef jv (*func_5)(jv,jv,jv,jv,jv);
      switch (function->nargs) {
      case 1: top = ((func_1)function->fptr)(in[0]); break;
      case 2: top = ((func_2)function->fptr)(in[0], in[1]); break;
      case 3: top = ((func_3)function->fptr)(in[0], in[1], in[2]); break;
      case 4: top = ((func_4)function->fptr)(in[0], in[1], in[2], in[3]); break;
      case 5: top = ((func_5)function->fptr)(in[0], in[1], in[2], in[3], in[4]); break;
      default: return jv_invalid_with_msg(jv_string("Function takes too many arguments"));
      }
      
      if (jv_is_valid(top)) {
        stack_push(jq, top);
      } else {
        print_error(jq, top);
        goto do_backtrack;
      }
      break;
    }

    case CALL_JQ: {
      jv input = stack_pop(jq);
      uint16_t nclosures = *pc++;
      uint16_t* retaddr = pc + 2 + nclosures*2;
      struct frame* new_frame = frame_push(jq, make_closure(jq, pc),
                                           pc + 2, nclosures);
      new_frame->retdata = jq->stk_top;
      new_frame->retaddr = retaddr;
      pc = new_frame->bc->code;
      stack_push(jq, input);
      break;
    }

    case RET: {
      jv value = stack_pop(jq);
      assert(jq->stk_top == frame_current(jq)->retdata);
      uint16_t* retaddr = frame_current(jq)->retaddr;
      if (retaddr) {
        // function return
        pc = retaddr;
        frame_pop(jq);
      } else {
        // top-level return, yielding value
        struct stack_pos spos = stack_get_pos(jq);
        stack_push(jq, jv_null());
        stack_save(jq, pc - 1, spos);
        return value;
      }
      stack_push(jq, value);
      break;
    }
    case ON_BACKTRACK(RET): {
      // resumed after top-level return
      goto do_backtrack;
    }
    }
  }
}
Ejemplo n.º 9
0
int main(int argc, char* argv[]) {
  if (argc) progname = argv[0];

  const char* program = 0;
  for (int i=1; i<argc; i++) {
    if (!isoptish(argv[i])) {
      if (program) usage();
      program = argv[i];
    } else if (isoption(argv[i], 's', "slurp")) {
      options |= SLURP;
    } else if (isoption(argv[i], 'r', "raw-output")) {
      options |= RAW_OUTPUT;
    } else if (isoption(argv[i], 'c', "compact-output")) {
      options |= COMPACT_OUTPUT;
    } else if (isoption(argv[i], 'a', "ascii-output")) {
      options |= ASCII_OUTPUT;
    } else if (isoption(argv[i], 'R', "raw-input")) {
      options |= RAW_INPUT;
    } else if (isoption(argv[i], 'n', "null-input")) {
      options |= PROVIDE_NULL;
    } else if (isoption(argv[i], 'h', "help")) {
      usage();
    } else {
      fprintf(stderr, "%s: Unknown option %s\n", progname, argv[i]);
      die();
    }
  }
  if (!program) usage();

  if ((options & PROVIDE_NULL) && (options & (RAW_INPUT | SLURP))) {
    fprintf(stderr, "%s: --null-input cannot be used with --raw-input or --slurp\n", program);
    die();
  }

  bc = jq_compile(program);
  if (!bc) return 1;

#if JQ_DEBUG
  dump_disassembly(0, bc);
  printf("\n");
#endif

  if (options & PROVIDE_NULL) {
    process(jv_null());
  } else {
    jv slurped;
    if (options & SLURP) slurped = jv_invalid();
    int first = 1;
    struct jv_parser parser;
    jv_parser_init(&parser);
    while (!feof(stdin)) {
      char buf[4096];
      if (!fgets(buf, sizeof(buf), stdin)) buf[0] = 0;
      if (options & RAW_INPUT) {
        int len = strlen(buf);
        if (len > 0) {
          if (options & SLURP) {
            if (first) slurped = jv_string(buf);
            else slurped = jv_string_concat(slurped, jv_string(buf));
          } else {
            if (buf[len-1] == '\n') buf[len-1] = 0;
            process(jv_string(buf));
          }
        }
      } else {
        jv_parser_set_buf(&parser, buf, strlen(buf), !feof(stdin));
        jv value;
        while (jv_is_valid((value = jv_parser_next(&parser)))) {
          if (options & SLURP) {
            if (first) slurped = jv_array();
            slurped = jv_array_append(slurped, value);
          } else {
            process(value);
          }
        }
        if (jv_invalid_has_msg(jv_copy(value))) {
          jv msg = jv_invalid_get_msg(value);
          fprintf(stderr, "parse error: %s\n", jv_string_value(msg));
          jv_free(msg);
          break;
        } else {
          jv_free(value);
        }
      }
      first = 0;
    }
    jv_parser_free(&parser);
    if (options & SLURP) {
      if (jv_is_valid(slurped)) {
        process(slurped);
      } else {
        jv_free(slurped);
      }
    }
  }

  bytecode_free(bc);
  return 0;
}
Ejemplo n.º 10
0
jv jq_next(jq_state *jq) {
  jv cfunc_input[MAX_CFUNCTION_ARGS];

  uint16_t* pc = stack_restore(jq);
  assert(pc);

  int backtracking = !jq->initial_execution;
  jq->initial_execution = 0;
  while (1) {
    uint16_t opcode = *pc;

    if (jq->debug_trace_enabled) {
      dump_operation(frame_current_bytecode(&jq->frame_stk), pc);
      printf("\t");
      const struct opcode_description* opdesc = opcode_describe(opcode);
      data_stk_elem* param = 0;
      int stack_in = opdesc->stack_in;
      if (stack_in == -1) stack_in = pc[1];
      for (int i=0; i<stack_in; i++) {
        if (i == 0) {
          param = forkable_stack_peek(&jq->data_stk);
        } else {
          printf(" | ");
          param = forkable_stack_peek_next(&jq->data_stk, param);
        }
        if (!param) break;
        jv_dump(jv_copy(param->val), 0);
        //printf("<%d>", jv_get_refcnt(param->val));
        //printf(" -- ");
        //jv_dump(jv_copy(jq->path), 0);
      }

      if (backtracking) printf("\t<backtracking>");

      printf("\n");
    }
    if (backtracking) {
      opcode = ON_BACKTRACK(opcode);
      backtracking = 0;
    }
    pc++;

    switch (opcode) {
    default: assert(0 && "invalid instruction");

    case LOADK: {
      jv v = jv_array_get(jv_copy(frame_current_bytecode(&jq->frame_stk)->constants), *pc++);
      assert(jv_is_valid(v));
      jv_free(stack_pop(jq));
      stack_push(jq, v);
      break;
    }

    case DUP: {
      jv v = stack_pop(jq);
      stack_push(jq, jv_copy(v));
      stack_push(jq, v);
      break;
    }

    case DUP2: {
      jv keep = stack_pop(jq);
      jv v = stack_pop(jq);
      stack_push(jq, jv_copy(v));
      stack_push(jq, keep);
      stack_push(jq, v);
      break;
    }

    case SUBEXP_BEGIN: {
      jv v = stack_pop(jq);
      stack_push(jq, jv_copy(v));
      stack_push(jq, v);
      jq->subexp_nest++;
      break;
    }

    case SUBEXP_END: {
      assert(jq->subexp_nest > 0);
      jq->subexp_nest--;
      jv a = stack_pop(jq);
      jv b = stack_pop(jq);
      stack_push(jq, a);
      stack_push(jq, b);
      break;
    }
      
    case POP: {
      jv_free(stack_pop(jq));
      break;
    }

    case APPEND: {
      jv v = stack_pop(jq);
      uint16_t level = *pc++;
      uint16_t vidx = *pc++;
      frame_ptr fp = frame_get_level(&jq->frame_stk, frame_current(&jq->frame_stk), level);
      jv* var = frame_local_var(fp, vidx);
      assert(jv_get_kind(*var) == JV_KIND_ARRAY);
      *var = jv_array_append(*var, v);
      break;
    }

    case INSERT: {
      jv stktop = stack_pop(jq);
      jv v = stack_pop(jq);
      jv k = stack_pop(jq);
      jv objv = stack_pop(jq);
      assert(jv_get_kind(objv) == JV_KIND_OBJECT);
      if (jv_get_kind(k) == JV_KIND_STRING) {
        stack_push(jq, jv_object_set(objv, k, v));
        stack_push(jq, stktop);
      } else {
        print_error(jv_invalid_with_msg(jv_string_fmt("Cannot use %s as object key",
                                                      jv_kind_name(jv_get_kind(k)))));
        jv_free(stktop);
        jv_free(v);
        jv_free(k);
        jv_free(objv);
        goto do_backtrack;
      }
      break;
    }

    case ON_BACKTRACK(RANGE):
    case RANGE: {
      uint16_t level = *pc++;
      uint16_t v = *pc++;
      frame_ptr fp = frame_get_level(&jq->frame_stk, frame_current(&jq->frame_stk), level);
      jv* var = frame_local_var(fp, v);
      jv max = stack_pop(jq);
      if (jv_get_kind(*var) != JV_KIND_NUMBER ||
          jv_get_kind(max) != JV_KIND_NUMBER) {
        print_error(jv_invalid_with_msg(jv_string_fmt("Range bounds must be numeric")));
        jv_free(max);
        goto do_backtrack;
      } else if (jv_number_value(jv_copy(*var)) >= jv_number_value(jv_copy(max))) {
        /* finished iterating */
        goto do_backtrack;
      } else {
        jv curr = jv_copy(*var);
        *var = jv_number(jv_number_value(*var) + 1);

        stack_save(jq, pc - 3);
        stack_push(jq, jv_copy(max));
        stack_switch(jq);
        stack_push(jq, curr);
      }
      break;
    }

      // FIXME: loadv/storev may do too much copying/freeing
    case LOADV: {
      uint16_t level = *pc++;
      uint16_t v = *pc++;
      frame_ptr fp = frame_get_level(&jq->frame_stk, frame_current(&jq->frame_stk), level);
      jv* var = frame_local_var(fp, v);
      if (jq->debug_trace_enabled) {
        printf("V%d = ", v);
        jv_dump(jv_copy(*var), 0);
        printf("\n");
      }
      jv_free(stack_pop(jq));
      stack_push(jq, jv_copy(*var));
      break;
    }

    case STOREV: {
      uint16_t level = *pc++;
      uint16_t v = *pc++;
      frame_ptr fp = frame_get_level(&jq->frame_stk, frame_current(&jq->frame_stk), level);
      jv* var = frame_local_var(fp, v);
      jv val = stack_pop(jq);
      if (jq->debug_trace_enabled) {
        printf("V%d = ", v);
        jv_dump(jv_copy(val), 0);
        printf("\n");
      }
      jv_free(*var);
      *var = val;
      break;
    }

    case PATH_BEGIN: {
      jv v = stack_pop(jq);
      stack_push(jq, jq->path);

      stack_save(jq, pc - 1);
      stack_switch(jq);

      stack_push(jq, jv_number(jq->subexp_nest));
      stack_push(jq, v);

      jq->path = jv_array();
      jq->subexp_nest = 0;
      break;
    }

    case PATH_END: {
      jv v = stack_pop(jq);
      jv_free(v); // discard value, only keep path

      int old_subexp_nest = (int)jv_number_value(stack_pop(jq));

      jv path = jq->path;
      jq->path = stack_pop(jq);

      stack_save(jq, pc - 1);
      stack_push(jq, jv_copy(path));
      stack_switch(jq);

      stack_push(jq, path);
      jq->subexp_nest = old_subexp_nest;
      break;
    }

    case ON_BACKTRACK(PATH_BEGIN):
    case ON_BACKTRACK(PATH_END): {
      jv_free(jq->path);
      jq->path = stack_pop(jq);
      goto do_backtrack;
    }

    case INDEX: {
      jv t = stack_pop(jq);
      jv k = stack_pop(jq);
      path_append(jq, jv_copy(k));
      jv v = jv_get(t, k);
      if (jv_is_valid(v)) {
        stack_push(jq, v);
      } else {
        print_error(v);
        goto do_backtrack;
      }
      break;
    }


    case JUMP: {
      uint16_t offset = *pc++;
      pc += offset;
      break;
    }

    case JUMP_F: {
      uint16_t offset = *pc++;
      jv t = stack_pop(jq);
      jv_kind kind = jv_get_kind(t);
      if (kind == JV_KIND_FALSE || kind == JV_KIND_NULL) {
        pc += offset;
      }
      stack_push(jq, t); // FIXME do this better
      break;
    }

    case EACH: 
      stack_push(jq, jv_number(-1));
      // fallthrough
    case ON_BACKTRACK(EACH): {
      int idx = jv_number_value(stack_pop(jq));
      jv container = stack_pop(jq);

      int keep_going;
      jv key, value;
      if (jv_get_kind(container) == JV_KIND_ARRAY) {
        if (opcode == EACH) idx = 0;
        else idx = idx + 1;
        keep_going = idx < jv_array_length(jv_copy(container));
        if (keep_going) {
          key = jv_number(idx);
          value = jv_array_get(jv_copy(container), idx);
        }
      } else if (jv_get_kind(container) == JV_KIND_OBJECT) {
        if (opcode == EACH) idx = jv_object_iter(container);
        else idx = jv_object_iter_next(container, idx);
        keep_going = jv_object_iter_valid(container, idx);
        if (keep_going) {
          key = jv_object_iter_key(container, idx);
          value = jv_object_iter_value(container, idx);
        }
      } else {
        assert(opcode == EACH);
        print_error(jv_invalid_with_msg(jv_string_fmt("Cannot iterate over %s",
                                                      jv_kind_name(jv_get_kind(container)))));
        keep_going = 0;
      }

      if (!keep_going) {
        jv_free(container);
        goto do_backtrack;
      } else {
        stack_save(jq, pc - 1);
        stack_push(jq, container);
        stack_push(jq, jv_number(idx));
        stack_switch(jq);
        path_append(jq, key);
        stack_push(jq, value);
      }
      break;
    }

    do_backtrack:
    case BACKTRACK: {
      pc = stack_restore(jq);
      if (!pc) {
        return jv_invalid();
      }
      backtracking = 1;
      break;
    }

    case FORK: {
      stack_save(jq, pc - 1);
      stack_switch(jq);
      pc++; // skip offset this time
      break;
    }

    case ON_BACKTRACK(FORK): {
      uint16_t offset = *pc++;
      pc += offset;
      break;
    }
      
    case CALL_BUILTIN: {
      int nargs = *pc++;
      jv top = stack_pop(jq);
      cfunc_input[0] = top;
      for (int i = 1; i < nargs; i++) {
        cfunc_input[i] = stack_pop(jq);
      }
      struct cfunction* func = &frame_current_bytecode(&jq->frame_stk)->globals->cfunctions[*pc++];
      top = cfunction_invoke(func, cfunc_input);
      if (jv_is_valid(top)) {
        stack_push(jq, top);
      } else {
        print_error(top);
        goto do_backtrack;
      }
      break;
    }

    case CALL_JQ: {
      uint16_t nclosures = *pc++;
      uint16_t* retaddr = pc + 2 + nclosures*2;
      frame_ptr new_frame = frame_push(&jq->frame_stk, 
                                       make_closure(&jq->frame_stk, frame_current(&jq->frame_stk), pc),
                                       retaddr);
      pc += 2;
      frame_ptr old_frame = forkable_stack_peek_next(&jq->frame_stk, new_frame);
      assert(nclosures == frame_self(new_frame)->bc->nclosures);
      for (int i=0; i<nclosures; i++) {
        *frame_closure_arg(new_frame, i) = make_closure(&jq->frame_stk, old_frame, pc);
        pc += 2;
      }

      pc = frame_current_bytecode(&jq->frame_stk)->code;
      break;
    }

    case RET: {
      uint16_t* retaddr = *frame_current_retaddr(&jq->frame_stk);
      if (retaddr) {
        // function return
        pc = retaddr;
        frame_pop(&jq->frame_stk);
      } else {
        // top-level return, yielding value
        jv value = stack_pop(jq);
        stack_save(jq, pc - 1);
        stack_push(jq, jv_null());
        stack_switch(jq);
        return value;
      }
      break;
    }
    case ON_BACKTRACK(RET): {
      // resumed after top-level return
      goto do_backtrack;
    }
    }
  }
}