SQLite

** Return negative for a syntax error.  Special cases:  return -2 if the
** first non-whitespace character is '}' and return -3 if the first
** non-whitespace character is ']'.
*/
static int jsonParseValue(JsonParse *pParse, u32 i){
  char c;
  u32 j;
  int iThis;
  int x;
  while( isspace(pParse->zJson[i]) ){ i++; }
  if( (c = pParse->zJson[i])==0 ) return 0;
  if( c=='{' ){
    /* Parse object */
    iThis = jsonParseAddNode(pParse, JSON_OBJECT, 0, 0);
    if( iThis<0 ) return -1;
    for(j=i+1;;j++){
      while( isspace(pParse->zJson[j]) ){ j++; }
      x = jsonParseValue(pParse, j);
      if( x<0 ){
        if( x==(-2) && pParse->nNode==(u32)iThis+1 ) return j+1;
        return -1;
      }
      if( pParse->oom ) return -1;
      if( pParse->aNode[pParse->nNode-1].eType!=JSON_STRING ) return -1;
      j = x;
      while( isspace(pParse->zJson[j]) ){ j++; }
      if( pParse->zJson[j]!=':' ) return -1;
      j++;
      x = jsonParseValue(pParse, j);
      if( x<0 ) return -1;
      j = x;
      while( isspace(pParse->zJson[j]) ){ j++; }
      c = pParse->zJson[j];
      if( c==',' ) continue;
      if( c!='}' ) return -1;
      break;
    }
    pParse->aNode[iThis].n = pParse->nNode - (u32)iThis - 1;
    return j+1;
  }else if( c=='[' ){
    /* Parse array */
    iThis = jsonParseAddNode(pParse, JSON_ARRAY, 0, 0);
    if( iThis<0 ) return -1;
    for(j=i+1;;j++){
      while( isspace(pParse->zJson[j]) ){ j++; }
      x = jsonParseValue(pParse, j);
      if( x<0 ){
        if( x==(-3) && pParse->nNode==(u32)iThis+1 ) return j+1;
        return -1;
      }
      j = x;
      while( isspace(pParse->zJson[j]) ){ j++; }
      c = pParse->zJson[j];
      if( c==',' ) continue;
      if( c!=']' ) return -1;
      break;
    }
    pParse->aNode[iThis].n = pParse->nNode - (u32)iThis - 1;
    return j+1;
  }else if( c=='"' ){
    /* Parse string */
    u8 jnFlags = 0;
    j = i+1;
    for(;;){
      c = pParse->zJson[j];

/*
** Parse a complete JSON string.  Return 0 on success or non-zero if there
** are any errors.  If an error occurs, free all memory associated with
** pParse.
**
** pParse is uninitialized when this routine is called.
*/
static int jsonParse(
  JsonParse *pParse,           /* Initialize and fill this JsonParse object */
  sqlite3_context *pCtx,       /* Report errors here */
  const char *zJson            /* Input JSON text to be parsed */
){
  int i;
  if( zJson==0 ) return 1;
  memset(pParse, 0, sizeof(*pParse));
  pParse->zJson = zJson;
  i = jsonParseValue(pParse, 0);
  if( i>0 ){
    while( isspace(zJson[i]) ) i++;
    if( zJson[i] ) i = -1;
  }
  if( i<0 ){
    if( pParse->oom && pCtx!=0 ) sqlite3_result_error_nomem(pCtx);
    jsonParseReset(pParse);
    return 1;
  }
  return 0;
}

/* Mark node i of pParse as being a child of iParent.  Call recursively

*/
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, nKey;
  const char *zKey;
  JsonNode *pRoot = &pParse->aNode[iRoot];
  if( zPath[0]==0 ) return pRoot;
  if( zPath[0]=='.' ){
    if( pRoot->eType!=JSON_OBJECT ) return 0;
    zPath++;
    if( zPath[0]=='"' ){

      }
      if( (pRoot->jnFlags & JNODE_APPEND)==0 ) break;
      iRoot += pRoot->u.iAppend;
      pRoot = &pParse->aNode[iRoot];
      j = 1;
    }
    if( pApnd ){
      u32 iStart, iLabel;
      JsonNode *pNode;
      iStart = jsonParseAddNode(pParse, JSON_OBJECT, 2, 0);


      iLabel = jsonParseAddNode(pParse, JSON_STRING, i, zPath);

      zPath += i;
      pNode = jsonLookupAppend(pParse, zPath, pApnd);
      if( pParse->oom ) return 0;
      if( pNode ){
        pRoot = &pParse->aNode[iRoot];
        pRoot->u.iAppend = iStart - iRoot;
        pRoot->jnFlags |= JNODE_APPEND;
        pParse->aNode[iLabel].jnFlags |= JNODE_RAW;
      }
      return pNode;
    }
  }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( j<=pRoot->n && (i>0 || (pRoot[j].jnFlags & JNODE_REMOVE)!=0) ){
        if( (pRoot[j].jnFlags & JNODE_REMOVE)==0 ) i--;
        j += jsonNodeSize(&pRoot[j]);

      }
      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 ){
      u32 iStart;
      JsonNode *pNode;
      iStart = jsonParseAddNode(pParse, JSON_ARRAY, 1, 0);
      pNode = jsonLookupAppend(pParse, zPath, pApnd);
      if( pParse->oom ) return 0;
      if( pNode ){
        pRoot = &pParse->aNode[iRoot];
        pRoot->u.iAppend = iStart - iRoot;
        pRoot->jnFlags |= JNODE_APPEND;
      }
      return pNode;
    }
  }
  return 0;
}

/*
** Append content to pParse that will complete zPath.  Return a pointer
** to the inserted node, or return NULL if the append fails.
*/
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;

  }else{
    return 0;
  }
  if( pParse->oom ) return 0;
  return jsonLookup(pParse, pParse->nNode-1, zPath, pApnd);
}

/*
** Report the wrong number of arguments for json_insert(), json_replace()
** or json_set().
*/
static void jsonWrongNumArgs(
  sqlite3_context *pCtx,
  const char *zFuncName
){
  char *zMsg = sqlite3_mprintf("json_%s() needs an odd number of arguments",
                               zFuncName);
  sqlite3_result_error(pCtx, zMsg, -1);
  sqlite3_free(zMsg);     
}

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

#ifdef SQLITE_DEBUG
/*
** The json_parse(JSON) function returns a string which describes
** a parse of the JSON provided.  Or it returns NULL if JSON is not
** well-formed.
*/
static void jsonParseFunc(
  sqlite3_context *ctx,
  int argc,
  sqlite3_value **argv
){
  JsonString s;       /* Output string - not real JSON */
  JsonParse x;        /* The parse */
  u32 i;
  char zBuf[100];

  assert( argc==1 );
  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
  jsonInit(&s, ctx);
  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);
    }
  }
  jsonParseReset(&x);
  jsonResult(&s);
}

/*
** The json_test1(JSON) function parses and rebuilds the JSON string.
*/
static void jsonTest1Func(
  sqlite3_context *ctx,
  int argc,
  sqlite3_value **argv
){
  JsonParse x;  /* The parse */
  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
  jsonReturn(x.aNode, ctx, 0);
  jsonParseReset(&x);
}

/*
** The json_nodecount(JSON) function returns the number of nodes in the
** input JSON string.
*/
static void jsonNodeCountFunc(
  sqlite3_context *ctx,
  int argc,
  sqlite3_value **argv
){
  JsonParse x;  /* The parse */
  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
  sqlite3_result_int64(ctx, (sqlite3_int64)x.nNode);
  jsonParseReset(&x);
}
#endif /* SQLITE_DEBUG */

/****************************************************************************
** SQL function implementations
****************************************************************************/

/*
** Implementation of the json_array(VALUE,...) function.  Return a JSON
** array that contains all values given in arguments.  Or if any argument
** is a BLOB, throw an error.
*/
static void jsonArrayFunc(
  sqlite3_context *ctx,
  int argc,
  sqlite3_value **argv
){
  int i;
  JsonString jx;

  jsonInit(&jx, ctx);
  jsonAppendChar(&jx, '[');
  for(i=0; i<argc; i++){
    jsonAppendSeparator(&jx);
    jsonAppendValue(&jx, argv[i]);
  }
  jsonAppendChar(&jx, ']');
  jsonResult(&jx);
}


/*
** json_array_length(JSON)
** json_array_length(JSON, PATH)
**
** Return the number of elements in the top-level JSON array.  
** Return 0 if the input is not a well-formed JSON array.
*/
static void jsonArrayLengthFunc(
  sqlite3_context *ctx,
  int argc,
  sqlite3_value **argv
){
  JsonParse x;          /* The parse */
  sqlite3_int64 n = 0;
  u32 i;
  const char *zPath;

  if( argc==2 ){
    zPath = (const char*)sqlite3_value_text(argv[1]);
    if( zPath==0 ) return;
    if( zPath[0]!='$' ) return;
    zPath++;
  }else{
    zPath = 0;
  }
  if( jsonParse(&x, ctx, (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 += jsonNodeSize(&pNode[i]);
        }
      }
    }
    jsonParseReset(&x);
  }
  if( !x.oom ) sqlite3_result_int64(ctx, n);
}

/*
** json_extract(JSON, PATH)
**
** Return the element described by PATH.  Return NULL if JSON is not
** valid JSON or if there is no PATH element or if PATH is malformed.
*/
static void jsonExtractFunc(
  sqlite3_context *ctx,
  int argc,
  sqlite3_value **argv
){
  JsonParse x;          /* The parse */
  JsonNode *pNode;
  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, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
  pNode = jsonLookup(&x, 0, zPath, 0);
  if( pNode ){
    jsonReturn(pNode, ctx, 0);
  }
  jsonParseReset(&x);
}

/*
** Implementation of the json_object(NAME,VALUE,...) function.  Return a JSON
** object that contains all name/value given in arguments.  Or if any name
** is not a string or if any value is a BLOB, throw an error.
*/
static void jsonObjectFunc(
  sqlite3_context *ctx,
  int argc,
  sqlite3_value **argv
){
  int i;
  JsonString jx;
  const char *z;
  u32 n;

  if( argc&1 ){
    sqlite3_result_error(ctx, "json_object() requires an even number "
                                  "of arguments", -1);
    return;
  }
  jsonInit(&jx, ctx);
  jsonAppendChar(&jx, '{');
  for(i=0; i<argc; i+=2){
    if( sqlite3_value_type(argv[i])!=SQLITE_TEXT ){
      sqlite3_result_error(ctx, "json_object() labels must be TEXT", -1);
      jsonZero(&jx);
      return;
    }
    jsonAppendSeparator(&jx);
    z = (const char*)sqlite3_value_text(argv[i]);
    n = (u32)sqlite3_value_bytes(argv[i]);
    jsonAppendString(&jx, z, n);

** json_remove(JSON, PATH, ...)
**
** Remove the named elements from JSON and return the result.  Ill-formed
** PATH arguments are silently ignored.  If JSON is ill-formed, then NULL
** is returned.
*/
static void jsonRemoveFunc(
  sqlite3_context *ctx,
  int argc,
  sqlite3_value **argv
){
  JsonParse x;          /* The parse */
  JsonNode *pNode;
  const char *zPath;
  u32 i;

  if( argc<1 ) return;
  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
  if( x.nNode ){
    for(i=1; i<(u32)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, ctx, 0);
    }
  }
  jsonParseReset(&x);
}

/*
** json_replace(JSON, PATH, VALUE, ...)
**
** Replace the value at PATH with VALUE.  If PATH does not already exist,
** this routine is a no-op.  If JSON is ill-formed, return NULL.
*/
static void jsonReplaceFunc(
  sqlite3_context *ctx,
  int argc,
  sqlite3_value **argv
){
  JsonParse x;          /* The parse */
  JsonNode *pNode;
  const char *zPath;
  u32 i;

  if( argc<1 ) return;
  if( (argc&1)==0 ) {

    jsonWrongNumArgs(ctx, "replace");
    return;
  }
  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
  if( x.nNode ){
    for(i=1; i<(u32)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(ctx, argv[x.aNode[0].iVal]);
    }else{
      jsonReturn(x.aNode, ctx, argv);
    }
  }
  jsonParseReset(&x);
}

/*
** 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 *ctx,
  int argc,
  sqlite3_value **argv
){
  JsonParse x;          /* The parse */
  JsonNode *pNode;
  const char *zPath;
  u32 i;
  int bApnd;
  int bIsSet = *(int*)sqlite3_user_data(ctx);

  if( argc<1 ) return;
  if( (argc&1)==0 ) {
    jsonWrongNumArgs(ctx, bIsSet ? "set" : "insert");

    return;
  }
  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
  if( x.nNode ){
    for(i=1; i<(u32)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( x.oom ){
        sqlite3_result_error_nomem(ctx);
        goto jsonSetDone;
      }else if( pNode && (bApnd || bIsSet) ){
        pNode->jnFlags |= JNODE_REPLACE;
        pNode->iVal = i+1;
      }
    }
    if( x.aNode[0].jnFlags & JNODE_REPLACE ){
      sqlite3_result_value(ctx, argv[x.aNode[0].iVal]);
    }else{
      jsonReturn(x.aNode, ctx, argv);
    }
  }
jsonSetDone:
  jsonParseReset(&x);
}

/*
** json_type(JSON)
** json_type(JSON, PATH)
**
** Return the top-level "type" of a JSON string.  Return NULL if the
** input is not a well-formed JSON string.
*/
static void jsonTypeFunc(
  sqlite3_context *ctx,
  int argc,
  sqlite3_value **argv
){
  JsonParse x;          /* The parse */
  const char *zPath;

  if( argc==2 ){
    zPath = (const char*)sqlite3_value_text(argv[1]);
    if( zPath==0 ) return;
    if( zPath[0]!='$' ) return;
    zPath++;
  }else{
    zPath = 0;
  }
  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
  if( x.nNode ){
    JsonNode *pNode = x.aNode;
    if( zPath ) pNode = jsonLookup(&x, 0, zPath, 0);
    if( pNode ){
      sqlite3_result_text(ctx, jsonType[pNode->eType], -1, SQLITE_STATIC);
    }
  }
  jsonParseReset(&x);
}

/*
** json_valid(JSON)
**
** Return 1 if JSON is a valid JSON string.  Return 0 otherwise.
*/
static void jsonValidFunc(
  sqlite3_context *ctx,
  int argc,
  sqlite3_value **argv
){
  JsonParse x;          /* The parse */
  int rc = 0;

  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0]))==0 
   && x.nNode>0
  ){
    rc = 1;
  }
  jsonParseReset(&x);
  sqlite3_result_int(ctx, rc);
}

/****************************************************************************
** The json_each virtual table
****************************************************************************/
typedef struct JsonEachCursor JsonEachCursor;
struct JsonEachCursor {

    zPath = (const char*)sqlite3_value_text(argv[1]);
    if( zPath==0 || zPath[0]!='$' ) return SQLITE_OK;
  }
  n = sqlite3_value_bytes(argv[0]);
  p->zJson = sqlite3_malloc64( n+1 );
  if( p->zJson==0 ) return SQLITE_NOMEM;
  memcpy(p->zJson, z, (size_t)n+1);
  if( jsonParse(&p->sParse, 0, p->zJson) 
   || (p->bRecursive && jsonParseFindParents(&p->sParse))
  ){
    jsonEachCursorReset(p);
  }else{
    JsonNode *pNode;
    if( idxNum==3 ){
      p->bRecursive = 0;

    if( p->eType>=JSON_ARRAY ){
      p->i++;
      p->iEnd = p->i + pNode->n;
    }else{
      p->iEnd = p->i+1;
    }
  }
  return p->sParse.oom ? SQLITE_NOMEM : SQLITE_OK;
}

/* The methods of the json_each virtual table */
static sqlite3_module jsonEachModule = {
  0,                         /* iVersion */
  0,                         /* xCreate */
  jsonEachConnect,           /* xConnect */

    { "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          },
    { "json_valid",           1, 0,   jsonValidFunc         },

#if SQLITE_DEBUG
    /* DEBUG and TESTING functions */
    { "json_parse",           1, 0,   jsonParseFunc         },
    { "json_test1",           1, 0,   jsonTest1Func         },
    { "json_nodecount",       1, 0,   jsonNodeCountFunc     },
#endif