srs/trunk/src/protocol/srs_protocol_json.cpp

/**
 * The MIT License (MIT)
 *
 * Copyright (c) 2013-2017 OSSRS(winlin)
 *
 * 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.
 */

#include <srs_protocol_json.hpp>

#include <sstream>
using namespace std;

#include <srs_kernel_log.hpp>
#include <srs_protocol_amf0.hpp>
#include <srs_kernel_utility.hpp>

/* json encode
 cout<< SRS_JOBJECT_START
 << SRS_JFIELD_STR("name", "srs") << SRS_JFIELD_CONT
 << SRS_JFIELD_ORG("version", 100) << SRS_JFIELD_CONT
 << SRS_JFIELD_NAME("features") << SRS_JOBJECT_START
 << SRS_JFIELD_STR("rtmp", "released") << SRS_JFIELD_CONT
 << SRS_JFIELD_STR("hls", "released") << SRS_JFIELD_CONT
 << SRS_JFIELD_STR("dash", "plan")
 << SRS_JOBJECT_END << SRS_JFIELD_CONT
 << SRS_JFIELD_STR("author", "srs team")
 << SRS_JOBJECT_END
 it's:
 cont<< "{"
 << "name:" << "srs" << ","
 << "version:" << 100 << ","
 << "features:" << "{"
 << "rtmp:" << "released" << ","
 << "hls:" << "released" << ","
 << "dash:" << "plan"
 << "}" << ","
 << "author:" << "srs team"
 << "}"
 that is:
 """
 {
 "name": "srs",
 "version": 100,
 "features": {
 "rtmp": "released",
 "hls": "released",
 "dash": "plan"
 },
 "author": "srs team"
 }
 """
 */
#define SRS_JOBJECT_START "{"
#define SRS_JFIELD_NAME(k) "\"" << k << "\":"
#define SRS_JFIELD_OBJ(k) SRS_JFIELD_NAME(k) << SRS_JOBJECT_START
#define SRS_JFIELD_STR(k, v) SRS_JFIELD_NAME(k) << "\"" << v << "\""
#define SRS_JFIELD_ORG(k, v) SRS_JFIELD_NAME(k) << std::dec << v
#define SRS_JFIELD_BOOL(k, v) SRS_JFIELD_ORG(k, (v? "true":"false"))
#define SRS_JFIELD_NULL(k) SRS_JFIELD_NAME(k) << "null"
#define SRS_JFIELD_ERROR(ret) "\"" << "code" << "\":" << ret
#define SRS_JFIELD_CONT ","
#define SRS_JOBJECT_END "}"
#define SRS_JARRAY_START "["
#define SRS_JARRAY_END "]"

#ifdef SRS_JSON_USE_NXJSON

////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////
/*
 * Copyright (c) 2013 Yaroslav Stavnichiy <yarosla@gmail.com>
 *
 * This file is part of NXJSON.
 *
 * NXJSON is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation, either version 3
 * of the License, or (at your option) any later version.
 *
 * NXJSON is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with NXJSON. If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef NXJSON_H
#define NXJSON_H

#ifdef  __cplusplus
extern "C" {
#endif
    
    
    typedef enum nx_json_type {
        NX_JSON_NULL,    // this is null value
        NX_JSON_OBJECT,  // this is an object; properties can be found in child nodes
        NX_JSON_ARRAY,   // this is an array; items can be found in child nodes
        NX_JSON_STRING,  // this is a string; value can be found in text_value field
        NX_JSON_INTEGER, // this is an integer; value can be found in int_value field
        NX_JSON_DOUBLE,  // this is a double; value can be found in dbl_value field
        NX_JSON_BOOL     // this is a boolean; value can be found in int_value field
    } nx_json_type;
    
    typedef struct nx_json {
        nx_json_type type;       // type of json node, see above
        const char* key;         // key of the property; for object's children only
        const char* text_value;  // text value of STRING node
        long int_value;          // the value of INTEGER or BOOL node
        double dbl_value;        // the value of DOUBLE node
        int length;              // number of children of OBJECT or ARRAY
        struct nx_json* child;   // points to first child
        struct nx_json* next;    // points to next child
        struct nx_json* last_child;
    } nx_json;
    
    typedef int (*nx_json_unicode_encoder)(unsigned int codepoint, char* p, char** endp);
    
    extern nx_json_unicode_encoder nx_json_unicode_to_utf8;
    
    const nx_json* nx_json_parse(char* text, nx_json_unicode_encoder encoder);
    const nx_json* nx_json_parse_utf8(char* text);
    void nx_json_free(const nx_json* js);
    const nx_json* nx_json_get(const nx_json* json, const char* key); // get object's property by key
    const nx_json* nx_json_item(const nx_json* json, int idx); // get array element by index
    
    
#ifdef  __cplusplus
}
#endif

#endif  /* NXJSON_H */

#endif

// Json marker
#define SRS_JSON_Boolean                   0x01
#define SRS_JSON_String                    0x02
#define SRS_JSON_Object                    0x03
#define SRS_JSON_Integer                   0x04
#define SRS_JSON_Number                    0x05
#define SRS_JSON_Null                      0x06
#define SRS_JSON_Array                     0x07

class SrsJsonString : public SrsJsonAny
{
public:
    std::string value;
    
    SrsJsonString(const char* _value)
    {
        marker = SRS_JSON_String;
        if (_value) {
            value = _value;
        }
    }
    virtual ~SrsJsonString()
    {
    }
};

class SrsJsonBoolean : public SrsJsonAny
{
public:
    bool value;
    
    SrsJsonBoolean(bool _value)
    {
        marker = SRS_JSON_Boolean;
        value = _value;
    }
    virtual ~SrsJsonBoolean()
    {
    }
};

class SrsJsonInteger : public SrsJsonAny
{
public:
    int64_t value;
    
    SrsJsonInteger(int64_t _value)
    {
        marker = SRS_JSON_Integer;
        value = _value;
    }
    virtual ~SrsJsonInteger()
    {
    }
};

class SrsJsonNumber : public SrsJsonAny
{
public:
    double value;
    
    SrsJsonNumber(double _value)
    {
        marker = SRS_JSON_Number;
        value = _value;
    }
    virtual ~SrsJsonNumber()
    {
    }
};

class SrsJsonNull : public SrsJsonAny
{
public:
    SrsJsonNull() {
        marker = SRS_JSON_Null;
    }
    virtual ~SrsJsonNull() {
    }
};

SrsJsonAny::SrsJsonAny()
{
    marker = 0;
}

SrsJsonAny::~SrsJsonAny()
{
}

bool SrsJsonAny::is_string()
{
    return marker == SRS_JSON_String;
}

bool SrsJsonAny::is_boolean()
{
    return marker == SRS_JSON_Boolean;
}

bool SrsJsonAny::is_number()
{
    return marker == SRS_JSON_Number;
}

bool SrsJsonAny::is_integer()
{
    return marker == SRS_JSON_Integer;
}

bool SrsJsonAny::is_object()
{
    return marker == SRS_JSON_Object;
}

bool SrsJsonAny::is_array()
{
    return marker == SRS_JSON_Array;
}

bool SrsJsonAny::is_null()
{
    return marker == SRS_JSON_Null;
}

string SrsJsonAny::to_str()
{
    SrsJsonString* p = dynamic_cast<SrsJsonString*>(this);
    srs_assert(p != NULL);
    return p->value;
}

bool SrsJsonAny::to_boolean()
{
    SrsJsonBoolean* p = dynamic_cast<SrsJsonBoolean*>(this);
    srs_assert(p != NULL);
    return p->value;
}

int64_t SrsJsonAny::to_integer()
{
    SrsJsonInteger* p = dynamic_cast<SrsJsonInteger*>(this);
    srs_assert(p != NULL);
    return p->value;
}

double SrsJsonAny::to_number()
{
    SrsJsonNumber* p = dynamic_cast<SrsJsonNumber*>(this);
    srs_assert(p != NULL);
    return p->value;
}

SrsJsonObject* SrsJsonAny::to_object()
{
    SrsJsonObject* p = dynamic_cast<SrsJsonObject*>(this);
    srs_assert(p != NULL);
    return p;
}

SrsJsonArray* SrsJsonAny::to_array()
{
    SrsJsonArray* p = dynamic_cast<SrsJsonArray*>(this);
    srs_assert(p != NULL);
    return p;
}

string SrsJsonAny::dumps()
{
    switch (marker) {
        case SRS_JSON_String: {
            return "\"" + to_str() + "\"";
        }
        case SRS_JSON_Boolean: {
            return to_boolean()? "true":"false";
        }
        case SRS_JSON_Integer: {
            return srs_int2str(to_integer());
        }
        case SRS_JSON_Number: {
            // len(max int64_t) is 20, plus one "+-."
            char tmp[22];
            snprintf(tmp, 22, "%.6f", to_number());
            return tmp;
        }
        case SRS_JSON_Null: {
            return "null";
        }
        case SRS_JSON_Object: {
            SrsJsonObject* obj = to_object();
            return obj->dumps();
        }
        case SRS_JSON_Array: {
            SrsJsonArray* arr = to_array();
            return arr->dumps();
        }
        default: {
            break;
        }
    }
    
    return "null";
}

SrsAmf0Any* SrsJsonAny::to_amf0()
{
    switch (marker) {
        case SRS_JSON_String: {
            return SrsAmf0Any::str(to_str().c_str());
        }
        case SRS_JSON_Boolean: {
            return SrsAmf0Any::boolean(to_boolean());
        }
        case SRS_JSON_Integer: {
            return SrsAmf0Any::number(to_integer());
        }
        case SRS_JSON_Number: {
            return SrsAmf0Any::number(to_number());
        }
        case SRS_JSON_Null: {
            return SrsAmf0Any::null();
        }
        case SRS_JSON_Object: {
            // json object must override this method.
            srs_assert(false);
        }
        case SRS_JSON_Array: {
            // json array must override this method.
            srs_assert(false);
        }
        default: {
            break;
        }
    }
    
    return SrsAmf0Any::null();
}

SrsJsonAny* SrsJsonAny::str(const char* value)
{
    return new SrsJsonString(value);
}

SrsJsonAny* SrsJsonAny::boolean(bool value)
{
    return new SrsJsonBoolean(value);
}

SrsJsonAny* SrsJsonAny::integer(int64_t value)
{
    return new SrsJsonInteger(value);
}

SrsJsonAny* SrsJsonAny::number(double value)
{
    return new SrsJsonNumber(value);
}

SrsJsonAny* SrsJsonAny::null()
{
    return new SrsJsonNull();
}

SrsJsonObject* SrsJsonAny::object()
{
    return new SrsJsonObject();
}

SrsJsonArray* SrsJsonAny::array()
{
    return new SrsJsonArray();
}

#ifdef SRS_JSON_USE_NXJSON
SrsJsonAny* srs_json_parse_tree_nx_json(const nx_json* node)
{
    if (!node) {
        return NULL;
    }
    
    switch (node->type) {
        case NX_JSON_NULL:
            return SrsJsonAny::null();
        case NX_JSON_STRING:
            return SrsJsonAny::str(node->text_value);
        case NX_JSON_INTEGER:
            return SrsJsonAny::integer(node->int_value);
        case NX_JSON_DOUBLE:
            return SrsJsonAny::number(node->dbl_value);
        case NX_JSON_BOOL:
            return SrsJsonAny::boolean(node->int_value != 0);
        case NX_JSON_OBJECT: {
            SrsJsonObject* obj = SrsJsonAny::object();
            for (nx_json* p = node->child; p != NULL; p = p->next) {
                SrsJsonAny* value = srs_json_parse_tree_nx_json(p);
                if (value) {
                    obj->set(p->key, value);
                }
            }
            return obj;
        }
        case NX_JSON_ARRAY: {
            SrsJsonArray* arr = SrsJsonAny::array();
            for (nx_json* p = node->child; p != NULL; p = p->next) {
                SrsJsonAny* value = srs_json_parse_tree_nx_json(p);
                if (value) {
                    arr->add(value);
                }
            }
            return arr;
        }
    }
    
    return NULL;
}

SrsJsonAny* SrsJsonAny::loads(char* str)
{
    if (!str) {
        return NULL;
    }
    
    if (strlen(str) == 0) {
        return NULL;
    }
    
    // TODO: copy str for nx_json modify it.
    string s = str;
    const nx_json* o = nx_json_parse((char*)s.data(), 0);
    
    SrsJsonAny* json = srs_json_parse_tree_nx_json(o);
    
    if (o) {
        nx_json_free(o);
    }
    
    return json;
}
#endif

SrsJsonObject::SrsJsonObject()
{
    marker = SRS_JSON_Object;
}

SrsJsonObject::~SrsJsonObject()
{
    std::vector<SrsJsonObjectPropertyType>::iterator it;
    for (it = properties.begin(); it != properties.end(); ++it) {
        SrsJsonObjectPropertyType item = *it;
        SrsJsonAny* obj = item.second;
        srs_freep(obj);
    }
    properties.clear();
}

int SrsJsonObject::count()
{
    return (int)properties.size();
}

string SrsJsonObject::key_at(int index)
{
    srs_assert(index < count());
    SrsJsonObjectPropertyType& elem = properties[index];
    return elem.first;
}

SrsJsonAny* SrsJsonObject::value_at(int index)
{
    srs_assert(index < count());
    SrsJsonObjectPropertyType& elem = properties[index];
    return elem.second;
}

string SrsJsonObject::dumps()
{
    stringstream ss;
    
    ss << SRS_JOBJECT_START;
    
    for (int i = 0; i < (int)properties.size(); i++) {
        std::string name = this->key_at(i);
        SrsJsonAny* any = this->value_at(i);
        
        ss << SRS_JFIELD_NAME(name) << any->dumps();
        if (i < (int)properties.size() - 1) {
            ss << SRS_JFIELD_CONT;
        }
    }
    
    ss << SRS_JOBJECT_END;
    
    return ss.str();
}

SrsAmf0Any* SrsJsonObject::to_amf0()
{
    SrsAmf0Object* obj = SrsAmf0Any::object();
    
    for (int i = 0; i < (int)properties.size(); i++) {
        std::string name = this->key_at(i);
        SrsJsonAny* any = this->value_at(i);
        
        obj->set(name, any->to_amf0());
    }
    
    return obj;
}

void SrsJsonObject::set(string key, SrsJsonAny* value)
{
    if (!value) {
        srs_warn("add a NULL propertity %s", key.c_str());
        return;
    }
    
    std::vector<SrsJsonObjectPropertyType>::iterator it;
    
    for (it = properties.begin(); it != properties.end(); ++it) {
        SrsJsonObjectPropertyType& elem = *it;
        std::string name = elem.first;
        SrsJsonAny* any = elem.second;
        
        if (key == name) {
            srs_freep(any);
            properties.erase(it);
            break;
        }
    }
    
    properties.push_back(std::make_pair(key, value));
}

SrsJsonAny* SrsJsonObject::get_property(string name)
{
    std::vector<SrsJsonObjectPropertyType>::iterator it;
    
    for (it = properties.begin(); it != properties.end(); ++it) {
        SrsJsonObjectPropertyType& elem = *it;
        std::string key = elem.first;
        SrsJsonAny* any = elem.second;
        if (key == name) {
            return any;
        }
    }
    
    return NULL;
}

SrsJsonAny* SrsJsonObject::ensure_property_string(string name)
{
    SrsJsonAny* prop = get_property(name);
    
    if (!prop) {
        return NULL;
    }
    
    if (!prop->is_string()) {
        return NULL;
    }
    
    return prop;
}

SrsJsonAny* SrsJsonObject::ensure_property_integer(string name)
{
    SrsJsonAny* prop = get_property(name);
    
    if (!prop) {
        return NULL;
    }
    
    if (!prop->is_integer()) {
        return NULL;
    }
    
    return prop;
}

SrsJsonAny* SrsJsonObject::ensure_property_number(string name)
{
    SrsJsonAny* prop = get_property(name);
    
    if (!prop) {
        return NULL;
    }
    
    if (!prop->is_number()) {
        return NULL;
    }
    
    return prop;
}

SrsJsonAny* SrsJsonObject::ensure_property_boolean(string name)
{
    SrsJsonAny* prop = get_property(name);
    
    if (!prop) {
        return NULL;
    }
    
    if (!prop->is_boolean()) {
        return NULL;
    }
    
    return prop;
}

SrsJsonAny* SrsJsonObject::ensure_property_object(string name)
{
    SrsJsonAny* prop = get_property(name);
    
    if (!prop) {
        return NULL;
    }
    
    if (!prop->is_object()) {
        return NULL;
    }
    
    return prop;
}

SrsJsonAny* SrsJsonObject::ensure_property_array(string name)
{
    SrsJsonAny* prop = get_property(name);
    
    if (!prop) {
        return NULL;
    }
    
    if (!prop->is_array()) {
        return NULL;
    }
    
    return prop;
}

SrsJsonArray::SrsJsonArray()
{
    marker = SRS_JSON_Array;
}

SrsJsonArray::~SrsJsonArray()
{
    std::vector<SrsJsonAny*>::iterator it;
    for (it = properties.begin(); it != properties.end(); ++it) {
        SrsJsonAny* item = *it;
        srs_freep(item);
    }
    properties.clear();
}

int SrsJsonArray::count()
{
    return (int)properties.size();
}

SrsJsonAny* SrsJsonArray::at(int index)
{
    srs_assert(index < count());
    SrsJsonAny* elem = properties[index];
    return elem;
}

void SrsJsonArray::add(SrsJsonAny* value)
{
    properties.push_back(value);
}

void SrsJsonArray::append(SrsJsonAny* value)
{
    add(value);
}

string SrsJsonArray::dumps()
{
    stringstream ss;
    
    ss << SRS_JARRAY_START;
    
    for (int i = 0; i < (int)properties.size(); i++) {
        SrsJsonAny* any = properties[i];
        
        ss << any->dumps();
        
        if (i < (int)properties.size() - 1) {
            ss << SRS_JFIELD_CONT;
        }
    }
    
    ss << SRS_JARRAY_END;
    
    return ss.str();
}

SrsAmf0Any* SrsJsonArray::to_amf0()
{
    SrsAmf0StrictArray* arr = SrsAmf0Any::strict_array();
    
    for (int i = 0; i < (int)properties.size(); i++) {
        SrsJsonAny* any = properties[i];
        
        arr->append(any->to_amf0());
    }
    
    return arr;
}

#ifdef SRS_JSON_USE_NXJSON

////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////
/*
 * Copyright (c) 2013 Yaroslav Stavnichiy <yarosla@gmail.com>
 *
 * This file is part of NXJSON.
 *
 * NXJSON is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation, either version 3
 * of the License, or (at your option) any later version.
 *
 * NXJSON is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with NXJSON. If not, see <http://www.gnu.org/licenses/>.
 */

// this file can be #included in your code
#ifndef NXJSON_C
#define NXJSON_C

#ifdef  __cplusplus
extern "C" {
#endif
    
    
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
    
    //#include "nxjson.h"
    
    // redefine NX_JSON_CALLOC & NX_JSON_FREE to use custom allocator
#ifndef NX_JSON_CALLOC
#define NX_JSON_CALLOC() calloc(1, sizeof(nx_json))
#define NX_JSON_FREE(json) free((void*)(json))
#endif
    
    // redefine NX_JSON_REPORT_ERROR to use custom error reporting
#ifndef NX_JSON_REPORT_ERROR
#define NX_JSON_REPORT_ERROR(msg, p) srs_warn("NXJSON PARSE ERROR (%d): " msg " at %s", __LINE__, p)
#endif
    
#define IS_WHITESPACE(c) ((unsigned char)(c)<=(unsigned char)' ')
    
    static const nx_json dummy={ NX_JSON_NULL };
    
    static nx_json* create_json(nx_json_type type, const char* key, nx_json* parent) {
        nx_json* js=(nx_json*)NX_JSON_CALLOC();
        memset(js, 0, sizeof(nx_json));
        assert(js);
        js->type=type;
        js->key=key;
        if (!parent->last_child) {
            parent->child=parent->last_child=js;
        }
        else {
            parent->last_child->next=js;
            parent->last_child=js;
        }
        parent->length++;
        return js;
    }
    
    void nx_json_free(const nx_json* js) {
        nx_json* p=js->child;
        nx_json* p1;
        while (p) {
            p1=p->next;
            nx_json_free(p);
            p=p1;
        }
        NX_JSON_FREE(js);
    }
    
    static int unicode_to_utf8(unsigned int codepoint, char* p, char** endp) {
        // code from http://stackoverflow.com/a/4609989/697313
        if (codepoint<0x80) *p++=codepoint;
        else if (codepoint<0x800) *p++=192+codepoint/64, *p++=128+codepoint%64;
        else if (codepoint-0xd800u<0x800) return 0; // surrogate must have been treated earlier
        else if (codepoint<0x10000) *p++=224+codepoint/4096, *p++=128+codepoint/64%64, *p++=128+codepoint%64;
        else if (codepoint<0x110000) *p++=240+codepoint/262144, *p++=128+codepoint/4096%64, *p++=128+codepoint/64%64, *p++=128+codepoint%64;
        else return 0; // error
        *endp=p;
        return 1;
    }
    
    nx_json_unicode_encoder nx_json_unicode_to_utf8=unicode_to_utf8;
    
    static inline int hex_val(char c) {
        if (c>='0' && c<='9') return c-'0';
        if (c>='a' && c<='f') return c-'a'+10;
        if (c>='A' && c<='F') return c-'A'+10;
        return -1;
    }
    
    static char* unescape_string(char* s, char** end, nx_json_unicode_encoder encoder) {
        char* p=s;
        char* d=s;
        char c;
        while ((c=*p++)) {
            if (c=='"') {
                *d='\0';
                *end=p;
                return s;
            }
            else if (c=='\\') {
                switch (*p) {
                    case '\\':
                    case '/':
                    case '"':
                        *d++=*p++;
                        break;
                    case 'b':
                        *d++='\b'; p++;
                        break;
                    case 'f':
                        *d++='\f'; p++;
                        break;
                    case 'n':
                        *d++='\n'; p++;
                        break;
                    case 'r':
                        *d++='\r'; p++;
                        break;
                    case 't':
                        *d++='\t'; p++;
                        break;
                    case 'u': { // unicode
                        if (!encoder) {
                            // leave untouched
                            *d++=c;
                            break;
                        }
                        char* ps=p-1;
                        int h1, h2, h3, h4;
                        if ((h1=hex_val(p[1]))<0 || (h2=hex_val(p[2]))<0 || (h3=hex_val(p[3]))<0 || (h4=hex_val(p[4]))<0) {
                            NX_JSON_REPORT_ERROR("invalid unicode escape", p-1);
                            return 0;
                        }
                        unsigned int codepoint=h1<<12|h2<<8|h3<<4|h4;
                        if ((codepoint & 0xfc00)==0xd800) { // high surrogate; need one more unicode to succeed
                            p+=6;
                            if (p[-1]!='\\' || *p!='u' || (h1=hex_val(p[1]))<0 || (h2=hex_val(p[2]))<0 || (h3=hex_val(p[3]))<0 || (h4=hex_val(p[4]))<0) {
                                NX_JSON_REPORT_ERROR("invalid unicode surrogate", ps);
                                return 0;
                            }
                            unsigned int codepoint2=h1<<12|h2<<8|h3<<4|h4;
                            if ((codepoint2 & 0xfc00)!=0xdc00) {
                                NX_JSON_REPORT_ERROR("invalid unicode surrogate", ps);
                                return 0;
                            }
                            codepoint=0x10000+((codepoint-0xd800)<<10)+(codepoint2-0xdc00);
                        }
                        if (!encoder(codepoint, d, &d)) {
                            NX_JSON_REPORT_ERROR("invalid codepoint", ps);
                            return 0;
                        }
                        p+=5;
                        break;
                    }
                    default: {
                        // leave untouched
                        *d++=c;
                        break;
                    }
                }
            }
            else {
                *d++=c;
            }
        }
        NX_JSON_REPORT_ERROR("no closing quote for string", s);
        return 0;
    }
    
    static char* skip_block_comment(char* p) {
        // assume p[-2]=='/' && p[-1]=='*'
        char* ps=p-2;
        if (!*p) {
            NX_JSON_REPORT_ERROR("endless comment", ps);
            return 0;
        }
    REPEAT:
        p=strchr(p+1, '/');
        if (!p) {
            NX_JSON_REPORT_ERROR("endless comment", ps);
            return 0;
        }
        if (p[-1]!='*') goto REPEAT;
        return p+1;
    }
    
    static char* parse_key(const char** key, char* p, nx_json_unicode_encoder encoder) {
        // on '}' return with *p=='}'
        char c;
        while ((c=*p++)) {
            if (c=='"') {
                *key=unescape_string(p, &p, encoder);
                if (!*key) return 0; // propagate error
                while (*p && IS_WHITESPACE(*p)) p++;
                if (*p==':') return p+1;
                NX_JSON_REPORT_ERROR("unexpected chars", p);
                return 0;
            }
            else if (IS_WHITESPACE(c) || c==',') {
                // continue
            }
            else if (c=='}') {
                return p-1;
            }
            else if (c=='/') {
                if (*p=='/') { // line comment
                    char* ps=p-1;
                    p=strchr(p+1, '\n');
                    if (!p) {
                        NX_JSON_REPORT_ERROR("endless comment", ps);
                        return 0; // error
                    }
                    p++;
                }
                else if (*p=='*') { // block comment
                    p=skip_block_comment(p+1);
                    if (!p) return 0;
                }
                else {
                    NX_JSON_REPORT_ERROR("unexpected chars", p-1);
                    return 0; // error
                }
            }
            else {
                NX_JSON_REPORT_ERROR("unexpected chars", p-1);
                return 0; // error
            }
        }
        NX_JSON_REPORT_ERROR("unexpected chars", p-1);
        return 0; // error
    }
    
    static char* parse_value(nx_json* parent, const char* key, char* p, nx_json_unicode_encoder encoder) {
        nx_json* js;
        while (1) {
            switch (*p) {
                case '\0':
                    NX_JSON_REPORT_ERROR("unexpected end of text", p);
                    return 0; // error
                case ' ': case '\t': case '\n': case '\r':
                case ',':
                    // skip
                    p++;
                    break;
                case '{':
                    js=create_json(NX_JSON_OBJECT, key, parent);
                    p++;
                    while (1) {
                        const char* new_key;
                        p=parse_key(&new_key, p, encoder);
                        if (!p) return 0; // error
                        if (*p=='}') return p+1; // end of object
                        p=parse_value(js, new_key, p, encoder);
                        if (!p) return 0; // error
                    }
                case '[':
                    js=create_json(NX_JSON_ARRAY, key, parent);
                    p++;
                    while (1) {
                        p=parse_value(js, 0, p, encoder);
                        if (!p) return 0; // error
                        if (*p==']') return p+1; // end of array
                    }
                case ']':
                    return p;
                case '"':
                    p++;
                    js=create_json(NX_JSON_STRING, key, parent);
                    js->text_value=unescape_string(p, &p, encoder);
                    if (!js->text_value) return 0; // propagate error
                    return p;
                case '-': case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9':
                {
                    js=create_json(NX_JSON_INTEGER, key, parent);
                    char* pe;
                    js->int_value=strtol(p, &pe, 0);
                    if (pe==p) {
                        NX_JSON_REPORT_ERROR("invalid number", p);
                        return 0; // error
                    }
                    if (*pe=='.' || *pe=='e' || *pe=='E') { // double value
                        js->type=NX_JSON_DOUBLE;
                        js->dbl_value=strtod(p, &pe);
                        if (pe==p) {
                            NX_JSON_REPORT_ERROR("invalid number", p);
                            return 0; // error
                        }
                    }
                    else {
                        js->dbl_value=js->int_value;
                    }
                    return pe;
                }
                case 't':
                    if (!strncmp(p, "true", 4)) {
                        js=create_json(NX_JSON_BOOL, key, parent);
                        js->int_value=1;
                        return p+4;
                    }
                    NX_JSON_REPORT_ERROR("unexpected chars", p);
                    return 0; // error
                case 'f':
                    if (!strncmp(p, "false", 5)) {
                        js=create_json(NX_JSON_BOOL, key, parent);
                        js->int_value=0;
                        return p+5;
                    }
                    NX_JSON_REPORT_ERROR("unexpected chars", p);
                    return 0; // error
                case 'n':
                    if (!strncmp(p, "null", 4)) {
                        create_json(NX_JSON_NULL, key, parent);
                        return p+4;
                    }
                    NX_JSON_REPORT_ERROR("unexpected chars", p);
                    return 0; // error
                case '/': // comment
                    if (p[1]=='/') { // line comment
                        char* ps=p;
                        p=strchr(p+2, '\n');
                        if (!p) {
                            NX_JSON_REPORT_ERROR("endless comment", ps);
                            return 0; // error
                        }
                        p++;
                    }
                    else if (p[1]=='*') { // block comment
                        p=skip_block_comment(p+2);
                        if (!p) return 0;
                    }
                    else {
                        NX_JSON_REPORT_ERROR("unexpected chars", p);
                        return 0; // error
                    }
                    break;
                default:
                    NX_JSON_REPORT_ERROR("unexpected chars", p);
                    return 0; // error
            }
        }
    }
    
    const nx_json* nx_json_parse_utf8(char* text) {
        return nx_json_parse(text, unicode_to_utf8);
    }
    
    const nx_json* nx_json_parse(char* text, nx_json_unicode_encoder encoder) {
        nx_json js;
        memset(&js, 0, sizeof(nx_json));
        if (!parse_value(&js, 0, text, encoder)) {
            if (js.child) nx_json_free(js.child);
            return 0;
        }
        return js.child;
    }
    
    const nx_json* nx_json_get(const nx_json* json, const char* key) {
        if (!json || !key) return &dummy; // never return null
        nx_json* js;
        for (js=json->child; js; js=js->next) {
            if (js->key && !strcmp(js->key, key)) return js;
        }
        return &dummy; // never return null
    }
    
    const nx_json* nx_json_item(const nx_json* json, int idx) {
        if (!json) return &dummy; // never return null
        nx_json* js;
        for (js=json->child; js; js=js->next) {
            if (!idx--) return js;
        }
        return &dummy; // never return null
    }
    
    
#ifdef  __cplusplus
}
#endif

#endif  /* NXJSON_C */

////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////

#endif