circuitpython/extmod/modujson.c

// SPDX-FileCopyrightText: 2014 MicroPython & CircuitPython contributors (https://github.com/adafruit/circuitpython/graphs/contributors)
// SPDX-FileCopyrightText: Copyright (c) 2014-2016 Damien P. George
//
// SPDX-License-Identifier: MIT

#include <stdio.h>

#include "py/binary.h"
#include "py/objarray.h"
#include "py/objlist.h"
#include "py/objstringio.h"
#include "py/parsenum.h"
#include "py/runtime.h"
#include "py/stream.h"

#include "supervisor/shared/translate.h"

#if MICROPY_PY_UJSON

STATIC mp_obj_t mod_ujson_dump(mp_obj_t obj, mp_obj_t stream) {
    mp_get_stream_raise(stream, MP_STREAM_OP_WRITE);
    mp_print_t print = {MP_OBJ_TO_PTR(stream), mp_stream_write_adaptor};
    mp_obj_print_helper(&print, obj, PRINT_JSON);
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_ujson_dump_obj, mod_ujson_dump);

STATIC mp_obj_t mod_ujson_dumps(mp_obj_t obj) {
    vstr_t vstr;
    mp_print_t print;
    vstr_init_print(&vstr, 8, &print);
    mp_obj_print_helper(&print, obj, PRINT_JSON);
    return mp_obj_new_str_from_vstr(&mp_type_str, &vstr);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_ujson_dumps_obj, mod_ujson_dumps);

#define JSON_DEBUG(...) (void)0
// #define JSON_DEBUG(...) mp_printf(&mp_plat_print __VA_OPT__(,) __VA_ARGS__)


// The function below implements a simple non-recursive JSON parser.
//
// The JSON specification is at http://www.ietf.org/rfc/rfc4627.txt
// The parser here will parse any valid JSON and return the correct
// corresponding Python object.  It allows through a superset of JSON, since
// it treats commas and colons as "whitespace", and doesn't care if
// brackets/braces are correctly paired.  It will raise a ValueError if the
// input is outside it's specs.
//
// Most of the work is parsing the primitives (null, false, true, numbers,
// strings).  It does 1 pass over the input stream.  It tries to be fast and
// small in code size, while not using more RAM than necessary.

typedef struct _ujson_stream_t {
    mp_obj_t stream_obj;
    mp_uint_t (*read)(mp_obj_t obj, void *buf, mp_uint_t size, int *errcode);
    int errcode;
    mp_obj_t python_readinto[2 + 1];
    mp_obj_array_t bytearray_obj;
    size_t start;
    size_t end;
    byte cur;
} ujson_stream_t;

#define S_EOF (0) // null is not allowed in json stream so is ok as EOF marker
#define S_END(s) ((s).cur == S_EOF)
#define S_CUR(s) ((s).cur)
#define S_NEXT(s) (ujson_stream_next(&(s)))

STATIC byte ujson_stream_next(ujson_stream_t *s) {
    mp_uint_t ret = s->read(s->stream_obj, &s->cur, 1, &s->errcode);
    JSON_DEBUG("  usjon_stream_next err:%2d cur: %c \n", s->errcode, s->cur);
    if (s->errcode != 0) {
        mp_raise_OSError(s->errcode);
    }
    if (ret == 0) {
        s->cur = S_EOF;
    }
    return s->cur;
}

// We read from an object's `readinto` method in chunks larger than the json
// parser needs to reduce the number of function calls done.

#define CIRCUITPY_JSON_READ_CHUNK_SIZE 64

STATIC mp_uint_t ujson_python_readinto(mp_obj_t obj, void *buf, mp_uint_t size, int *errcode) {
    (void)size;  // Ignore size because we know it's always 1.
    ujson_stream_t *s = obj;

    if (s->start == s->end) {
        *errcode = 0;
        mp_obj_t ret = mp_call_method_n_kw(1, 0, s->python_readinto);
        if (ret == mp_const_none) {
            *errcode = MP_EAGAIN;
            return MP_STREAM_ERROR;
        }
        s->start = 0;
        s->end = mp_obj_get_int(ret);
    }

    *((uint8_t *)buf) = ((uint8_t *)s->bytearray_obj.items)[s->start];
    s->start++;
    return 1;
}

STATIC mp_obj_t _mod_ujson_load(mp_obj_t stream_obj, bool return_first_json) {
    const mp_stream_p_t *stream_p = mp_proto_get(MP_QSTR_protocol_stream, stream_obj);
    ujson_stream_t s;
    uint8_t character_buffer[CIRCUITPY_JSON_READ_CHUNK_SIZE];
    if (stream_p == NULL) {
        s.start = 0;
        s.end = 0;
        mp_load_method(stream_obj, MP_QSTR_readinto, s.python_readinto);
        s.bytearray_obj.base.type = &mp_type_bytearray;
        s.bytearray_obj.typecode = BYTEARRAY_TYPECODE;
        s.bytearray_obj.len = CIRCUITPY_JSON_READ_CHUNK_SIZE;
        s.bytearray_obj.free = 0;
        s.bytearray_obj.items = character_buffer;
        s.python_readinto[2] = MP_OBJ_FROM_PTR(&s.bytearray_obj);
        s.stream_obj = &s;
        s.read = ujson_python_readinto;
    } else {
        stream_p = mp_get_stream_raise(stream_obj, MP_STREAM_OP_READ);
        s.stream_obj = stream_obj;
        s.read = stream_p->read;
        s.errcode = 0;
        s.cur = 0;
    }

    JSON_DEBUG("got JSON stream\n");
    vstr_t vstr;
    vstr_init(&vstr, 8);
    mp_obj_list_t stack; // we use a list as a simple stack for nested JSON
    stack.len = 0;
    stack.items = NULL;
    mp_obj_t stack_top = MP_OBJ_NULL;
    mp_obj_type_t *stack_top_type = NULL;
    mp_obj_t stack_key = MP_OBJ_NULL;
    S_NEXT(s);
    for (;;) {
    cont:
        if (S_END(s)) {
            break;
        }
        mp_obj_t next = MP_OBJ_NULL;
        bool enter = false;
        byte cur = S_CUR(s);
        S_NEXT(s);
        switch (cur) {
            case ',':
            case ':':
            case ' ':
            case '\t':
            case '\n':
            case '\r':
                goto cont;
            case 'n':
                if (S_CUR(s) == 'u' && S_NEXT(s) == 'l' && S_NEXT(s) == 'l') {
                    S_NEXT(s);
                    next = mp_const_none;
                } else {
                    goto fail;
                }
                break;
            case 'f':
                if (S_CUR(s) == 'a' && S_NEXT(s) == 'l' && S_NEXT(s) == 's' && S_NEXT(s) == 'e') {
                    S_NEXT(s);
                    next = mp_const_false;
                } else {
                    goto fail;
                }
                break;
            case 't':
                if (S_CUR(s) == 'r' && S_NEXT(s) == 'u' && S_NEXT(s) == 'e') {
                    S_NEXT(s);
                    next = mp_const_true;
                } else {
                    goto fail;
                }
                break;
            case '"':
                vstr_reset(&vstr);
                for (; !S_END(s) && S_CUR(s) != '"';) {
                    byte c = S_CUR(s);
                    if (c == '\\') {
                        c = S_NEXT(s);
                        switch (c) {
                            case 'b':
                                c = 0x08;
                                break;
                            case 'f':
                                c = 0x0c;
                                break;
                            case 'n':
                                c = 0x0a;
                                break;
                            case 'r':
                                c = 0x0d;
                                break;
                            case 't':
                                c = 0x09;
                                break;
                            case 'u': {
                                mp_uint_t num = 0;
                                for (int i = 0; i < 4; i++) {
                                    c = (S_NEXT(s) | 0x20) - '0';
                                    if (c > 9) {
                                        c -= ('a' - ('9' + 1));
                                    }
                                    num = (num << 4) | c;
                                }
                                vstr_add_char(&vstr, num);
                                goto str_cont;
                            }
                        }
                    }
                    vstr_add_byte(&vstr, c);
                str_cont:
                    S_NEXT(s);
                }
                if (S_END(s)) {
                    goto fail;
                }
                S_NEXT(s);
                next = mp_obj_new_str(vstr.buf, vstr.len);
                break;
            case '-':
            case '0':
            case '1':
            case '2':
            case '3':
            case '4':
            case '5':
            case '6':
            case '7':
            case '8':
            case '9': {
                bool flt = false;
                vstr_reset(&vstr);
                for (;;) {
                    vstr_add_byte(&vstr, cur);
                    cur = S_CUR(s);
                    if (cur == '.' || cur == 'E' || cur == 'e') {
                        flt = true;
                    } else if (cur == '+' || cur == '-' || unichar_isdigit(cur)) {
                        // pass
                    } else {
                        break;
                    }
                    S_NEXT(s);
                }
                if (flt) {
                    next = mp_parse_num_decimal(vstr.buf, vstr.len, false, false, NULL);
                } else {
                    next = mp_parse_num_integer(vstr.buf, vstr.len, 10, NULL);
                }
                break;
            }
            case '[':
                next = mp_obj_new_list(0, NULL);
                enter = true;
                break;
            case '{':
                next = mp_obj_new_dict(0);
                enter = true;
                break;
            case '}':
            case ']': {
                if (stack_top == MP_OBJ_NULL) {
                    // no object at all
                    goto fail;
                }
                if (stack.len == 0) {
                    // finished; compound object
                    goto success;
                }
                stack.len -= 1;
                stack_top = stack.items[stack.len];
                stack_top_type = mp_obj_get_type(stack_top);
                goto cont;
            }
            default:
                goto fail;
        }
        if (stack_top == MP_OBJ_NULL) {
            stack_top = next;
            stack_top_type = mp_obj_get_type(stack_top);
            if (!enter) {
                // finished; single primitive only
                goto success;
            }
        } else {
            // append to list or dict
            if (stack_top_type == &mp_type_list) {
                mp_obj_list_append(stack_top, next);
            } else {
                if (stack_key == MP_OBJ_NULL) {
                    stack_key = next;
                    if (enter) {
                        goto fail;
                    }
                } else {
                    mp_obj_dict_store(stack_top, stack_key, next);
                    stack_key = MP_OBJ_NULL;
                }
            }
            if (enter) {
                if (stack.items == NULL) {
                    mp_obj_list_init(&stack, 1);
                    stack.items[0] = stack_top;
                } else {
                    mp_obj_list_append(MP_OBJ_FROM_PTR(&stack), stack_top);
                }
                stack_top = next;
                stack_top_type = mp_obj_get_type(stack_top);
            }
        }
    }
success:
    // It is legal for a stream to have contents after JSON.
    // E.g., A UART is not closed after receiving an object; in load() we will
    //   return the first complete JSON object, while in loads() we will retain
    //   strict adherence to the buffer's complete semantic.
    if (!return_first_json) {
        while (unichar_isspace(S_CUR(s))) {
            S_NEXT(s);
        }
        if (!S_END(s)) {
            // unexpected chars
            goto fail;
        }
    }
    if (stack_top == MP_OBJ_NULL || stack.len != 0) {
        // not exactly 1 object
        goto fail;
    }
    vstr_clear(&vstr);
    return stack_top;

fail:
    mp_raise_ValueError(translate("syntax error in JSON"));
}

STATIC mp_obj_t mod_ujson_load(mp_obj_t stream_obj) {
    return _mod_ujson_load(stream_obj, true);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_ujson_load_obj, mod_ujson_load);

STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
    size_t len;
    const char *buf = mp_obj_str_get_data(obj, &len);
    vstr_t vstr = {len, len, (char *)buf, true};
    mp_obj_stringio_t sio = {{&mp_type_stringio}, &vstr, 0, MP_OBJ_NULL};
    return _mod_ujson_load(MP_OBJ_FROM_PTR(&sio), false);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_ujson_loads_obj, mod_ujson_loads);

STATIC const mp_rom_map_elem_t mp_module_ujson_globals_table[] = {
    #if CIRCUITPY
    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_json) },
    #else
    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_ujson) },
    #endif
    { MP_ROM_QSTR(MP_QSTR_dump), MP_ROM_PTR(&mod_ujson_dump_obj) },
    { MP_ROM_QSTR(MP_QSTR_dumps), MP_ROM_PTR(&mod_ujson_dumps_obj) },
    { MP_ROM_QSTR(MP_QSTR_load), MP_ROM_PTR(&mod_ujson_load_obj) },
    { MP_ROM_QSTR(MP_QSTR_loads), MP_ROM_PTR(&mod_ujson_loads_obj) },
};

STATIC MP_DEFINE_CONST_DICT(mp_module_ujson_globals, mp_module_ujson_globals_table);

const mp_obj_module_t mp_module_ujson = {
    .base = { &mp_type_module },
    .globals = (mp_obj_dict_t *)&mp_module_ujson_globals,
};

#endif // MICROPY_PY_UJSON