SQLite

#include <stdlib.h>

/* Unsigned integer types */
typedef sqlite3_uint64 u64;
typedef unsigned int u32;
typedef unsigned char u8;

/* Objects */
typedef struct Json Json;
typedef struct JsonNode JsonNode;
typedef struct JsonParse JsonParse;

/* An instance of this object represents a JSON string
** under construction.  Really, this is a generic string accumulator
** that can be and is used to create strings other than JSON.
*/

struct Json {
  sqlite3_context *pCtx;   /* Function context - put error messages here */
  char *zBuf;              /* Append JSON content here */
  u64 nAlloc;              /* Bytes of storage available in zBuf[] */
  u64 nUsed;               /* Bytes of zBuf[] currently used */
  u8 bStatic;              /* True if zBuf is static space */
  u8 bErr;                 /* True if an error has been encountered */

/* Bit values for the JsonNode.jnFlag field
*/
#define JNODE_RAW     0x01         /* Content is raw, not JSON encoded */
#define JNODE_ESCAPE  0x02         /* Content is text with \ escapes */
#define JNODE_REMOVE  0x04         /* Do not output */
#define JNODE_REPLACE 0x08         /* Replace with JsonNode.iVal */
#define JNODE_APPEND  0x10         /* More ARRAY/OBJECT entries at u.iAppend */


/* A single node of parsed JSON
*/

struct JsonNode {
  u8 eType;              /* One of the JSON_ type values */
  u8 jnFlags;            /* JNODE flags */
  u8 iVal;               /* Replacement value when JNODE_REPLACE */
  u32 n;                 /* Bytes of content, or number of sub-nodes */
  union {
    const char *zJContent; /* JSON content */
    u32 iAppend;           /* Appended content */
  } u;
};

/* A completely parsed JSON string
*/

struct JsonParse {
  u32 nNode;         /* Number of slots of aNode[] used */
  u32 nAlloc;        /* Number of slots of aNode[] allocated */
  JsonNode *aNode;   /* Array of nodes containing the parse */
  const char *zJson; /* Original JSON string */
  u8 oom;            /* Set to true if out of memory */
};

/*
** Return the number of consecutive JsonNode slots need to represent
** the parsed JSON at pNode.  The minimum answer is 1.  For ARRAY and
** OBJECT types, the number might be larger.
**
** Appended elements are not counted.  The value returned is the number
** by which the JsonNode counter should increment in order to go to the
** next peer value.
*/
static u32 jsonSize(JsonNode *pNode){
  return pNode->eType>=JSON_ARRAY ? pNode->n+1 : 1;
}

/* Set the Json object to an empty string
*/

}

/*
** Convert the JsonNode pNode into a pure JSON string and
** append to pOut.  Subsubstructure is also included.  Return
** the number of JsonNode objects that are encoded.
*/
static void jsonRenderNode(
  JsonNode *pNode,               /* The node to render */
  Json *pOut,                    /* Write JSON here */
  sqlite3_value **aReplace       /* Replacement values */
){

  switch( pNode->eType ){
    case JSON_NULL: {
      jsonAppendRaw(pOut, "null", 4);
      break;
    }
    case JSON_TRUE: {
      jsonAppendRaw(pOut, "true", 4);
      break;
    }
    case JSON_FALSE: {
      jsonAppendRaw(pOut, "false", 5);
      break;
    }
    case JSON_STRING: {
      if( pNode->jnFlags & JNODE_RAW ){
        jsonAppendString(pOut, pNode->u.zJContent, pNode->n);
        break;
      }
      /* Fall through into the next case */
    }
    case JSON_REAL:
    case JSON_INT: {
      jsonAppendRaw(pOut, pNode->u.zJContent, pNode->n);
      break;
    }
    case JSON_ARRAY: {
      u32 j = 1;
      jsonAppendChar(pOut, '[');
      for(;;){
        while( j<=pNode->n ){
          if( pNode[j].jnFlags & (JNODE_REMOVE|JNODE_REPLACE) ){
            if( pNode[j].jnFlags & JNODE_REPLACE ){
              jsonAppendSeparator(pOut);
              jsonAppendValue(pOut, aReplace[pNode[j].iVal]);
            }

          }else{
            jsonAppendSeparator(pOut);
            jsonRenderNode(&pNode[j], pOut, aReplace);
          }
          j += jsonSize(&pNode[j]);
        }
        if( (pNode->jnFlags & JNODE_APPEND)==0 ) break;
        pNode = &pNode[pNode->u.iAppend];
        j = 1;
      }
      jsonAppendChar(pOut, ']');
      break;
    }
    case JSON_OBJECT: {
      u32 j = 1;
      jsonAppendChar(pOut, '{');
      for(;;){
        while( j<=pNode->n ){
          if( (pNode[j+1].jnFlags & JNODE_REMOVE)==0 ){


            jsonAppendSeparator(pOut);
            jsonRenderNode(&pNode[j], pOut, aReplace);
            jsonAppendChar(pOut, ':');
            if( pNode[j+1].jnFlags & JNODE_REPLACE ){
              jsonAppendValue(pOut, aReplace[pNode[j+1].iVal]);

            }else{
              jsonRenderNode(&pNode[j+1], pOut, aReplace);
            }
          }
          j += 1 + jsonSize(&pNode[j+1]);
        }
        if( (pNode->jnFlags & JNODE_APPEND)==0 ) break;
        pNode = &pNode[pNode->u.iAppend];
        j = 1;
      }
      jsonAppendChar(pOut, '}');
      break;
    }
  }

}

/*
** Make the JsonNode the return value of the function.
*/
static void jsonReturn(
  JsonNode *pNode,            /* Node to return */

      break;
    }
    case JSON_FALSE: {
      sqlite3_result_int(pCtx, 0);
      break;
    }
    case JSON_REAL: {
      double r = strtod(pNode->u.zJContent, 0);
      sqlite3_result_double(pCtx, r);
      break;
    }
    case JSON_INT: {
      sqlite3_int64 i = 0;
      const char *z = pNode->u.zJContent;
      if( z[0]=='-' ){ z++; }
      while( z[0]>='0' && z[0]<='9' ){ i = i*10 + *(z++) - '0'; }
      if( pNode->u.zJContent[0]=='-' ){ i = -i; }
      sqlite3_result_int64(pCtx, i);
      break;
    }
    case JSON_STRING: {
      if( pNode->jnFlags & JNODE_RAW ){
        sqlite3_result_text(pCtx, pNode->u.zJContent, pNode->n,
                            SQLITE_TRANSIENT);
      }else if( (pNode->jnFlags & JNODE_ESCAPE)==0 ){
        /* JSON formatted without any backslash-escapes */
        sqlite3_result_text(pCtx, pNode->u.zJContent+1, pNode->n-2,
                            SQLITE_TRANSIENT);
      }else{
        /* Translate JSON formatted string into raw text */
        u32 i;
        u32 n = pNode->n;
        const char *z = pNode->u.zJContent;
        char *zOut;
        u32 j;
        zOut = sqlite3_malloc( n+1 );
        if( zOut==0 ){
          sqlite3_result_error_nomem(pCtx);
          break;
        }

    pParse->aNode = pNew;
  }
  p = &pParse->aNode[pParse->nNode];
  p->eType = (u8)eType;
  p->jnFlags = 0;
  p->iVal = 0;
  p->n = n;
  p->u.zJContent = zContent;
  return pParse->nNode++;
}

/*
** Parse a single JSON value which begins at pParse->zJson[i].  Return the
** index of the first character past the end of the value parsed.
**

    pParse->nNode = 0;
    pParse->nAlloc = 0;
    return 1;
  }
  return 0;
}

/* forward declaration */
static JsonNode *jsonLookupAppend(JsonParse*,const char*,int*);

/*
** Search along zPath to find the node specified.  Return a pointer
** to that node, or NULL if zPath is malformed or if there is no such
** node.
**
** If pApnd!=0, then try to append new nodes to complete zPath if it is
** possible to do so and if no existing node corresponds to zPath.  If
** new nodes are appended *pApnd is set to 1.
*/
static JsonNode *jsonLookup(
  JsonParse *pParse,      /* The JSON to search */
  u32 iRoot,              /* Begin the search at this node */
  const char *zPath,      /* The path to search */
  int *pApnd              /* Append nodes to complete path if not NULL */
){
  u32 i, j, k;
  JsonNode *pRoot = &pParse->aNode[iRoot];
  if( zPath[0]==0 ) return pRoot;
  if( zPath[0]=='.' ){
    if( pRoot->eType!=JSON_OBJECT ) return 0;
    zPath++;
    for(i=0; isalnum(zPath[i]); i++){}
    if( i==0 ) return 0;
    j = 1;
    for(;;){
      while( j<=pRoot->n ){
        if( pRoot[j].n==i+2
         && strncmp(&pRoot[j].u.zJContent[1],zPath,i)==0
        ){
          return jsonLookup(pParse, iRoot+j+1, &zPath[i], pApnd);
        }
        j++;
        j += jsonSize(&pRoot[j]);
      }
      if( (pRoot->jnFlags & JNODE_APPEND)==0 ) break;
      iRoot += pRoot->u.iAppend;
      pRoot = &pParse->aNode[iRoot];
      j = 1;
    }
    if( pApnd ){
      k = jsonParseAddNode(pParse, JSON_OBJECT, 2, 0);
      pRoot->u.iAppend = k - iRoot;
      pRoot->jnFlags |= JNODE_APPEND;
      k = jsonParseAddNode(pParse, JSON_STRING, i, zPath);
      if( !pParse->oom ) pParse->aNode[k].jnFlags |= JNODE_RAW;
      zPath += i;
      return jsonLookupAppend(pParse, zPath, pApnd);
    }
  }else if( zPath[0]=='[' && isdigit(zPath[1]) ){
    if( pRoot->eType!=JSON_ARRAY ) return 0;
    i = 0;
    zPath++;
    while( isdigit(zPath[0]) ){
      i = i + zPath[0] - '0';
      zPath++;
    }
    if( zPath[0]!=']' ) return 0;
    zPath++;
    j = 1;
    for(;;){
      while( i>0 && j<=pRoot->n ){
        j += jsonSize(&pRoot[j]);
        i--;
      }
      if( (pRoot->jnFlags & JNODE_APPEND)==0 ) break;
      iRoot += pRoot->u.iAppend;
      pRoot = &pParse->aNode[iRoot];
      j = 1;
    }
    if( j<=pRoot->n ){
      return jsonLookup(pParse, iRoot+j, zPath, pApnd);
    }
    if( i==0 && pApnd ){
      k = jsonParseAddNode(pParse, JSON_ARRAY, 1, 0);
      pRoot->u.iAppend = k - iRoot;
      pRoot->jnFlags |= JNODE_APPEND;
      return jsonLookupAppend(pParse, zPath, pApnd);
    }
  }
  return 0;
}

/*
** Append content to pParse that will complete zPath.
*/
static JsonNode *jsonLookupAppend(
  JsonParse *pParse,     /* Append content to the JSON parse */
  const char *zPath,     /* Description of content to append */
  int *pApnd             /* Set this flag to 1 */
){
  *pApnd = 1;
  if( zPath[0]==0 ){
    jsonParseAddNode(pParse, JSON_NULL, 0, 0);
    return pParse->oom ? 0 : &pParse->aNode[pParse->nNode-1];
  }
  if( zPath[0]=='.' ){
    jsonParseAddNode(pParse, JSON_OBJECT, 0, 0);
  }else if( strncmp(zPath,"[0]",3)==0 ){
    jsonParseAddNode(pParse, JSON_ARRAY, 0, 0);
  }else{
    return 0;
  }
  if( pParse->oom ) return 0;
  return jsonLookup(pParse, pParse->nNode-1, zPath, pApnd);
}


/****************************************************************************
** SQL functions used for testing and debugging
****************************************************************************/

#ifdef SQLITE_DEBUG
/*

  assert( argc==1 );
  if( jsonParse(&x, (const char*)sqlite3_value_text(argv[0])) ) return;
  jsonInit(&s, context);
  for(i=0; i<x.nNode; i++){
    sqlite3_snprintf(sizeof(zBuf), zBuf, "node %3u: %7s n=%d\n",
                     i, jsonType[x.aNode[i].eType], x.aNode[i].n);
    jsonAppend(&s, zBuf);
    if( x.aNode[i].u.zJContent!=0 ){
      jsonAppendRaw(&s, "    text: ", 10);
      jsonAppendRaw(&s, x.aNode[i].u.zJContent, x.aNode[i].n);
      jsonAppendRaw(&s, "\n", 1);
    }
  }
  sqlite3_free(x.aNode);
  jsonResult(&s);
}

    zPath++;
  }else{
    zPath = 0;
  }
  if( jsonParse(&x, (const char*)sqlite3_value_text(argv[0]))==0 ){
    if( x.nNode ){
      JsonNode *pNode = x.aNode;
      if( zPath ) pNode = jsonLookup(&x, 0, zPath, 0);
      if( pNode->eType==JSON_ARRAY ){
        assert( (pNode->jnFlags & JNODE_APPEND)==0 );
        for(i=1; i<=pNode->n; n++){
          i += jsonSize(&pNode[i]);
        }
      }
    }
    sqlite3_free(x.aNode);
  }

  const char *zPath;
  assert( argc==2 );
  zPath = (const char*)sqlite3_value_text(argv[1]);
  if( zPath==0 ) return;
  if( zPath[0]!='$' ) return;
  zPath++;
  if( jsonParse(&x, (const char*)sqlite3_value_text(argv[0])) ) return;
  pNode = jsonLookup(&x, 0, zPath, 0);
  if( pNode ){
    jsonReturn(pNode, context, 0);
  }
  sqlite3_free(x.aNode);
}

/*

  if( argc<1 ) return;
  if( jsonParse(&x, (const char*)sqlite3_value_text(argv[0])) ) return;
  if( x.nNode ){
    for(i=1; i<argc; i++){
      zPath = (const char*)sqlite3_value_text(argv[i]);
      if( zPath==0 ) continue;
      if( zPath[0]!='$' ) continue;
      pNode = jsonLookup(&x, 0, &zPath[1], 0);
      if( pNode ) pNode->jnFlags |= JNODE_REMOVE;
    }
    if( (x.aNode[0].jnFlags & JNODE_REMOVE)==0 ){
      jsonReturn(x.aNode, context, 0);
    }
  }
  sqlite3_free(x.aNode);

  }
  if( jsonParse(&x, (const char*)sqlite3_value_text(argv[0])) ) return;
  if( x.nNode ){
    for(i=1; i<argc; i+=2){
      zPath = (const char*)sqlite3_value_text(argv[i]);
      if( zPath==0 ) continue;
      if( zPath[0]!='$' ) continue;
      pNode = jsonLookup(&x, 0, &zPath[1], 0);
      if( pNode ){
        pNode->jnFlags |= JNODE_REPLACE;
        pNode->iVal = i+1;
      }
    }
    if( x.aNode[0].jnFlags & JNODE_REPLACE ){
      sqlite3_result_value(context, argv[x.aNode[0].iVal]);
    }else{
      jsonReturn(x.aNode, context, argv);
    }
  }
  sqlite3_free(x.aNode);
}
/*
** json_set(JSON, PATH, VALUE, ...)
**
** Set the value at PATH to VALUE.  Create the PATH if it does not already
** exist.  Overwrite existing values that do exist.
** If JSON is ill-formed, return NULL.
**
** json_insert(JSON, PATH, VALUE, ...)
**
** Create PATH and initialize it to VALUE.  If PATH already exists, this
** routine is a no-op.  If JSON is ill-formed, return NULL.
*/
static void jsonSetFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  JsonParse x;          /* The parse */
  JsonNode *pNode;
  const char *zPath;
  u32 i;
  int bApnd;
  int bIsSet = *(int*)sqlite3_user_data(context);

  if( argc<1 ) return;
  if( (argc&1)==0 ) {
    sqlite3_result_error(context,
                         "json_set() needs an odd number of arguments", -1);
    return;
  }
  if( jsonParse(&x, (const char*)sqlite3_value_text(argv[0])) ) return;
  if( x.nNode ){
    for(i=1; i<argc; i+=2){
      zPath = (const char*)sqlite3_value_text(argv[i]);
      if( zPath==0 ) continue;
      if( zPath[0]!='$' ) continue;
      bApnd = 0;
      pNode = jsonLookup(&x, 0, &zPath[1], &bApnd);
      if( pNode && (bApnd || bIsSet) ){
        pNode->jnFlags |= JNODE_REPLACE;
        pNode->iVal = i+1;
      }
    }
    if( x.aNode[0].jnFlags & JNODE_REPLACE ){
      sqlite3_result_value(context, argv[x.aNode[0].iVal]);
    }else{
      jsonReturn(x.aNode, context, argv);
    }
  }

    zPath++;
  }else{
    zPath = 0;
  }
  if( jsonParse(&x, (const char*)sqlite3_value_text(argv[0])) ) return;
  if( x.nNode ){
    JsonNode *pNode = x.aNode;
    if( zPath ) pNode = jsonLookup(&x, 0, zPath, 0);
    sqlite3_result_text(context, jsonType[pNode->eType], -1, SQLITE_STATIC);
  }
  sqlite3_free(x.aNode);
}

#ifdef _WIN32
__declspec(dllexport)
#endif
int sqlite3_json_init(
  sqlite3 *db, 
  char **pzErrMsg, 
  const sqlite3_api_routines *pApi
){
  int rc = SQLITE_OK;
  int i;
  static const struct {
     const char *zName;
     int nArg;
     int flag;
     void (*xFunc)(sqlite3_context*,int,sqlite3_value**);
  } aFunc[] = {
    { "json_array",          -1, 0,   jsonArrayFunc         },
    { "json_array_length",    1, 0,   jsonArrayLengthFunc   },
    { "json_array_length",    2, 0,   jsonArrayLengthFunc   },
    { "json_extract",         2, 0,   jsonExtractFunc       },
    { "json_insert",         -1, 0,   jsonSetFunc           },
    { "json_object",         -1, 0,   jsonObjectFunc        },
    { "json_remove",         -1, 0,   jsonRemoveFunc        },
    { "json_replace",        -1, 0,   jsonReplaceFunc       },
    { "json_set",            -1, 1,   jsonSetFunc           },
    { "json_type",            1, 0,   jsonTypeFunc          },
    { "json_type",            2, 0,   jsonTypeFunc          },

#if SQLITE_DEBUG
    /* DEBUG and TESTING functions */
    { "json_parse",           1, 0,   jsonParseFunc         },
    { "json_test1",           1, 0,   jsonTest1Func         },
    { "json_nodecount",       1, 0,   jsonNodeCountFunc     },
#endif
  };
  SQLITE_EXTENSION_INIT2(pApi);
  (void)pzErrMsg;  /* Unused parameter */
  for(i=0; i<sizeof(aFunc)/sizeof(aFunc[0]) && rc==SQLITE_OK; i++){
    rc = sqlite3_create_function(db, aFunc[i].zName, aFunc[i].nArg,
                                 SQLITE_UTF8 | SQLITE_DETERMINISTIC, 
                                 (void*)&aFunc[i].flag,
                                 aFunc[i].xFunc, 0, 0);
  }
  return rc;
}