json.h

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/* Simple Plugin API
 *
 * Copyright © 2020 Wim Taymans
 *
 * 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 (including the next
 * paragraph) 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 SPA_UTILS_JSON_H
#define SPA_UTILS_JSON_H
 
#ifdef __cplusplus
extern "C" {
#else
#include <stdbool.h>
#endif
#include <stddef.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
 
#include <spa/utils/defs.h>
 
/* a simple JSON compatible tokenizer */
struct spa_json {
        const char *cur;
        const char *end;
        struct spa_json *parent;
        uint32_t state;
        uint32_t depth;
};
 
#define SPA_JSON_INIT(data,size) (struct spa_json) { (data), (data)+(size), }
 
static inline void spa_json_init(struct spa_json * iter, const char *data, size_t size)
{
        *iter =  SPA_JSON_INIT(data, size);
}
#define SPA_JSON_ENTER(iter) (struct spa_json) { (iter)->cur, (iter)->end, (iter), }
 
static inline void spa_json_enter(struct spa_json * iter, struct spa_json * sub)
{
        *sub = SPA_JSON_ENTER(iter);
}
 
#define SPA_JSON_SAVE(iter) (struct spa_json) { (iter)->cur, (iter)->end, }
 
static inline int spa_json_next(struct spa_json * iter, const char **value)
{
        int utf8_remain = 0;
        enum { __NONE, __STRUCT, __BARE, __STRING, __UTF8, __ESC, __COMMENT };
 
        *value = iter->cur;
        for (; iter->cur < iter->end; iter->cur++) {
                unsigned char cur = (unsigned char)*iter->cur;
 again:
                switch (iter->state) {
                case __NONE:
                        iter->state = __STRUCT;
                        iter->depth = 0;
                        goto again;
                case __STRUCT:
                        switch (cur) {
                        case '\0': case '\t': case ' ': case '\r': case '\n': case ':': case '=': case ',':
                                continue;
                        case '#':
                                iter->state = __COMMENT;
                                continue;
                        case '"':
                                *value = iter->cur;
                                iter->state = __STRING;
                                continue;
                        case '[': case '{':
                                *value = iter->cur;
                                if (++iter->depth > 1)
                                        continue;
                                iter->cur++;
                                return 1;
                        case '}': case ']':
                                if (iter->depth == 0) {
                                        if (iter->parent)
                                                iter->parent->cur = iter->cur;
                                        return 0;
                                }
                                --iter->depth;
                                continue;
                        default:
                                *value = iter->cur;
                                iter->state = __BARE;
                        }
                        continue;
                case __BARE:
                        switch (cur) {
                        case '\t': case ' ': case '\r': case '\n':
                        case ':': case ',': case '=': case ']': case '}':
                                iter->state = __STRUCT;
                                if (iter->depth > 0)
                                        goto again;
                                return iter->cur - *value;
                        }
                        continue;
                case __STRING:
                        switch (cur) {
                        case '\\':
                                iter->state = __ESC;
                                continue;
                        case '"':
                                iter->state = __STRUCT;
                                if (iter->depth > 0)
                                        continue;
                                return ++iter->cur - *value;
                        case 240 ... 247:
                                utf8_remain++;
                                SPA_FALLTHROUGH;
                        case 224 ... 239:
                                utf8_remain++;
                                SPA_FALLTHROUGH;
                        case 192 ... 223:
                                utf8_remain++;
                                iter->state = __UTF8;
                                continue;
                        default:
                                if (cur >= 32 && cur <= 126)
                                        continue;
                        }
                        return -1;
                case __UTF8:
                        switch (cur) {
                        case 128 ... 191:
                                if (--utf8_remain == 0)
                                        iter->state = __STRING;
                                continue;
                        }
                        return -1;
                case __ESC:
                        switch (cur) {
                        case '"': case '\\': case '/': case 'b': case 'f':
                        case 'n': case 'r': case 't': case 'u':
                                iter->state = __STRING;
                                continue;
                        }
                        return -1;
                case __COMMENT:
                        switch (cur) {
                        case '\n': case '\r':
                                iter->state = __STRUCT;
                        }
                }
 
        }
        if (iter->depth != 0)
                return -1;
        if (iter->state != __STRUCT) {
                iter->state = __STRUCT;
                return iter->cur - *value;
        }
        return 0;
}
 
static inline int spa_json_enter_container(struct spa_json *iter, struct spa_json *sub, char type)
{
        const char *value;
        if (spa_json_next(iter, &value) <= 0 || *value != type)
                return -1;
        spa_json_enter(iter, sub);
        return 1;
}
 
static inline int spa_json_is_container(const char *val, int len)
{
        return len > 0 && (*val == '{'  || *val == '[');
}
 
static inline int spa_json_container_len(struct spa_json *iter, const char *value, int len)
{
        const char *val;
        struct spa_json sub;
        spa_json_enter(iter, &sub);
        while (spa_json_next(&sub, &val) > 0);
        return sub.cur + 1 - value;
}
 
/* object */
static inline int spa_json_is_object(const char *val, int len)
{
        return len > 0 && *val == '{';
}
static inline int spa_json_enter_object(struct spa_json *iter, struct spa_json *sub)
{
        return spa_json_enter_container(iter, sub, '{');
}
 
/* array */
static inline bool spa_json_is_array(const char *val, int len)
{
        return len > 0 && *val == '[';
}
static inline int spa_json_enter_array(struct spa_json *iter, struct spa_json *sub)
{
        return spa_json_enter_container(iter, sub, '[');
}
 
/* null */
static inline bool spa_json_is_null(const char *val, int len)
{
        return len == 4 && strncmp(val, "null", 4) == 0;
}
 
/* float */
static inline int spa_json_parse_float(const char *val, int len, float *result)
{
        char *end;
        *result = strtof(val, &end);
        return end == val + len;
}
static inline bool spa_json_is_float(const char *val, int len)
{
        float dummy;
        return spa_json_parse_float(val, len, &dummy);
}
static inline int spa_json_get_float(struct spa_json *iter, float *res)
{
        const char *value;
        int len;
        if ((len = spa_json_next(iter, &value)) <= 0)
                return -1;
        return spa_json_parse_float(value, len, res);
}
 
/* int */
static inline int spa_json_parse_int(const char *val, int len, int *result)
{
        char *end;
        *result = strtol(val, &end, 0);
        return end == val + len;
}
static inline bool spa_json_is_int(const char *val, int len)
{
        int dummy;
        return spa_json_parse_int(val, len, &dummy);
}
static inline int spa_json_get_int(struct spa_json *iter, int *res)
{
        const char *value;
        int len;
        if ((len = spa_json_next(iter, &value)) <= 0)
                return -1;
        return spa_json_parse_int(value, len, res);
}
 
/* bool */
static inline bool spa_json_is_true(const char *val, int len)
{
        return len == 4 && strncmp(val, "true", 4) == 0;
}
 
static inline bool spa_json_is_false(const char *val, int len)
{
        return len == 5 && strncmp(val, "false", 5) == 0;
}
 
static inline bool spa_json_is_bool(const char *val, int len)
{
        return spa_json_is_true(val, len) || spa_json_is_false(val, len);
}
 
static inline int spa_json_parse_bool(const char *val, int len, bool *result)
{
        if ((*result = spa_json_is_true(val, len)))
                return 1;
        if (!(*result = !spa_json_is_false(val, len)))
                return 1;
        return -1;
}
static inline int spa_json_get_bool(struct spa_json *iter, bool *res)
{
        const char *value;
        int len;
        if ((len = spa_json_next(iter, &value)) <= 0)
                return -1;
        return spa_json_parse_bool(value, len, res);
}
 
/* string */
static inline bool spa_json_is_string(const char *val, int len)
{
        return len > 1 && *val == '"';
}
 
static inline int spa_json_parse_stringn(const char *val, int len, char *result, int maxlen)
{
        const char *p;
        if (maxlen <= len)
                return -1;
        if (!spa_json_is_string(val, len)) {
                if (result != val)
                        strncpy(result, val, len);
                result += len;
        } else {
                for (p = val+1; p < val + len; p++) {
                        if (*p == '\\') {
                                p++;
                                if (*p == 'n')
                                        *result++ = '\n';
                                else if (*p == 'r')
                                        *result++ = '\r';
                                else if (*p == 'b')
                                        *result++ = '\b';
                                else if (*p == 't')
                                        *result++ = '\t';
                                else if (*p == 'f')
                                        *result++ = '\f';
                                else if (*p == 'u') {
                                        char *end;
                                        uint16_t v = strtol(p+1, &end, 16);
                                        if (p+1 == end) {
                                                *result++ = *p;
                                        } else {
                                                p = end-1;
                                                if (v > 0xff)
                                                        *result++ = (v >> 8) & 0xff;
                                                *result++ = v & 0xff;
                                        }
                                } else
                                        *result++ = *p;
                        } else if (*p == '\"') {
                                break;
                        } else
                                *result++ = *p;
                }
        }
        *result = '\0';
        return 1;
}
 
static inline int spa_json_parse_string(const char *val, int len, char *result)
{
        return spa_json_parse_stringn(val, len, result, len+1);
}
 
static inline int spa_json_get_string(struct spa_json *iter, char *res, int maxlen)
{
        const char *value;
        int len;
        if ((len = spa_json_next(iter, &value)) <= 0)
                return -1;
        return spa_json_parse_stringn(value, len, res, maxlen);
}
 
static inline int spa_json_encode_string(char *str, int size, const char *val)
{
        int len = 0;
        static const char hex[] = { "0123456789abcdef" };
#define __PUT(c) { if (len < size) *str++ = c; len++; }
        __PUT('"');
        while (*val) {
                switch (*val) {
                case '\n':
                        __PUT('\\'); __PUT('n');
                        break;
                case '\r':
                        __PUT('\\'); __PUT('r');
                        break;
                case '\b':
                        __PUT('\\'); __PUT('b');
                        break;
                case '\t':
                        __PUT('\\'); __PUT('t');
                        break;
                case '\f':
                        __PUT('\\'); __PUT('f');
                        break;
                case '\\':
                case '"':
                        __PUT('\\'); __PUT(*val);
                        break;
                default:
                        if (*val > 0 && *val < 0x20) {
                                __PUT('\\'); __PUT('u');
                                __PUT('0'); __PUT('0');
                                __PUT(hex[((*val)>>4)&0xf]); __PUT(hex[(*val)&0xf]);
                        } else {
                                __PUT(*val);
                        }
                        break;
                }
                val++;
        }
        __PUT('"');
        __PUT('\0');
#undef __PUT
        return len-1;
}
 
#ifdef __cplusplus
} /* extern "C" */
#endif
 
#endif /* SPA_UTILS_JSON_H */