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extmod/modujson: Implement ujson.load() to load JSON from a stream. 

This refactors ujson.loads(s) to behave as ujson.load(StringIO(s)).

Increase in code size is: 366 bytes for unix x86-64, 180 bytes for
stmhal, 84 bytes for esp8266.
This commit is contained in:
Damien George 2016-10-13 11:43:28 +11:00
parent f17f3314d0
commit e93c1ca5da
3 changed files with 109 additions and 44 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

105
extmod/modujson.c
View File

@ -3,7 +3,7 @@
*
* The MIT License (MIT)
*
* Copyright (c) 2014 Damien P. George
* Copyright (c) 2014-2016 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
@ -28,8 +28,10 @@
#include "py/nlr.h"
#include "py/objlist.h"
#include "py/objstringio.h"
#include "py/parsenum.h"
#include "py/runtime.h"
#include "py/stream.h"
#if MICROPY_PY_UJSON
@ -42,7 +44,7 @@ STATIC mp_obj_t mod_ujson_dumps(mp_obj_t obj) {
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_ujson_dumps_obj, mod_ujson_dumps);
// This function implements a simple non-recursive JSON parser.
// 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
@ -52,13 +54,35 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_ujson_dumps_obj, mod_ujson_dumps);
// 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 string and so is easily extended to
// being able to parse from a non-seekable stream. It tries to be fast and
// 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.
STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
mp_uint_t len;
const char *s = mp_obj_str_get_data(obj, &len);
const char *top = s + len;
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;
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);
if (s->errcode != 0) {
mp_raise_OSError(s->errcode);
}
if (ret == 0) {
s->cur = S_EOF;
}
return s->cur;
}
STATIC mp_obj_t mod_ujson_load(mp_obj_t stream_obj) {
const mp_stream_p_t *stream_p = mp_get_stream_raise(stream_obj, MP_STREAM_OP_READ);
ujson_stream_t s = {stream_obj, stream_p->read, 0, 0};
vstr_t vstr;
vstr_init(&vstr, 8);
mp_obj_list_t stack; // we use a list as a simple stack for nested JSON
@ -67,41 +91,43 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
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 == top) {
if (S_END(s)) {
break;
}
mp_obj_t next = MP_OBJ_NULL;
bool enter = false;
switch (*s) {
byte cur = S_CUR(s);
S_NEXT(s);
switch (cur) {
case ',':
case ':':
case ' ':
case '\t':
case '\n':
case '\r':
s += 1;
goto cont;
case 'n':
if (s + 3 < top && s[1] == 'u' && s[2] == 'l' && s[3] == 'l') {
s += 4;
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 + 4 < top && s[1] == 'a' && s[2] == 'l' && s[3] == 's' && s[4] == 'e') {
s += 5;
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 + 3 < top && s[1] == 'r' && s[2] == 'u' && s[3] == 'e') {
s += 4;
if (S_CUR(s) == 'r' && S_NEXT(s) == 'u' && S_NEXT(s) == 'e') {
S_NEXT(s);
next = mp_const_true;
} else {
goto fail;
@ -109,11 +135,10 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
break;
case '"':
vstr_reset(&vstr);
for (s++; s < top && *s != '"';) {
byte c = *s;
for (; !S_END(s) && S_CUR(s) != '"';) {
byte c = S_CUR(s);
if (c == '\\') {
s++;
c = *s;
c = S_NEXT(s);
switch (c) {
case 'b': c = 0x08; break;
case 'f': c = 0x0c; break;
@ -121,10 +146,9 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
case 'r': c = 0x0d; break;
case 't': c = 0x09; break;
case 'u': {
if (s + 4 >= top) { goto fail; }
mp_uint_t num = 0;
for (int i = 0; i < 4; i++) {
c = (*++s | 0x20) - '0';
c = (S_NEXT(s) | 0x20) - '0';
if (c > 9) {
c -= ('a' - ('9' + 1));
}
@ -137,27 +161,29 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
}
vstr_add_byte(&vstr, c);
str_cont:
s++;
S_NEXT(s);
}
if (s == top) {
if (S_END(s)) {
goto fail;
}
s++;
S_NEXT(s);
next = mp_obj_new_str(vstr.buf, vstr.len, false);
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 (; s < top; s++) {
if (*s == '.' || *s == 'E' || *s == 'e') {
for (;;) {
vstr_add_byte(&vstr, cur);
cur = S_CUR(s);
if (cur == '.' || cur == 'E' || cur == 'e') {
flt = true;
} else if (*s == '-' || unichar_isdigit(*s)) {
} else if (cur == '-' || unichar_isdigit(cur)) {
// pass
} else {
break;
}
vstr_add_byte(&vstr, *s);
S_NEXT(s);
}
if (flt) {
next = mp_parse_num_decimal(vstr.buf, vstr.len, false, false, NULL);
@ -169,16 +195,13 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
case '[':
next = mp_obj_new_list(0, NULL);
enter = true;
s += 1;
break;
case '{':
next = mp_obj_new_dict(0);
enter = true;
s += 1;
break;
case '}':
case ']': {
s += 1;
if (stack_top == MP_OBJ_NULL) {
// no object at all
goto fail;
@ -231,10 +254,10 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
}
success:
// eat trailing whitespace
while (s < top && unichar_isspace(*s)) {
s++;
while (unichar_isspace(S_CUR(s))) {
S_NEXT(s);
}
if (s < top) {
if (!S_END(s)) {
// unexpected chars
goto fail;
}
@ -248,11 +271,21 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
fail:
nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "syntax error in JSON"));
}
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) {
mp_uint_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};
return mod_ujson_load(&sio);
}
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[] = {
{ MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_ujson) },
{ 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) },
};

8
py/objstringio.c
View File

@ -30,18 +30,12 @@
#include "py/nlr.h"
#include "py/objstr.h"
#include "py/objstringio.h"
#include "py/runtime.h"
#include "py/stream.h"
#if MICROPY_PY_IO
typedef struct _mp_obj_stringio_t {
mp_obj_base_t base;
vstr_t *vstr;
// StringIO has single pointer used for both reading and writing
mp_uint_t pos;
} mp_obj_stringio_t;
#if MICROPY_CPYTHON_COMPAT
STATIC void check_stringio_is_open(const mp_obj_stringio_t *o) {
if (o->vstr == NULL) {

38
py/objstringio.h Normal file
View File

@ -0,0 +1,38 @@
/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2016 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef MICROPY_INCLUDED_PY_OBJSTRINGIO_H
#define MICROPY_INCLUDED_PY_OBJSTRINGIO_H
#include "py/obj.h"
typedef struct _mp_obj_stringio_t {
mp_obj_base_t base;
vstr_t *vstr;
// StringIO has single pointer used for both reading and writing
mp_uint_t pos;
} mp_obj_stringio_t;
#endif // MICROPY_INCLUDED_PY_OBJSTRINGIO_H