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/* |
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** Copyright (c) 2019 D. Richard Hipp |
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** |
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** This program is free software; you can redistribute it and/or |
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** modify it under the terms of the Simplified BSD License (also |
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** known as the "2-Clause License" or "FreeBSD License".) |
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** |
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** This program is distributed in the hope that it will be useful, |
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** but without any warranty; without even the implied warranty of |
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** merchantability or fitness for a particular purpose. |
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** |
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** Author contact information: |
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** [email protected] |
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** http://www.hwaci.com/drh/ |
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** |
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******************************************************************************* |
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** |
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** This module implements SQL interfaces to the delta logic. The code |
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** here is adapted from the ext/misc/fossildelta.c extension in SQLite. |
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*/ |
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#include "config.h" |
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#include "deltafunc.h" |
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/* |
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** SQL functions: delta_create(X,Y) |
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** |
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** Return a delta that will transform X into Y. |
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*/ |
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static void deltaCreateFunc( |
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sqlite3_context *context, |
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int argc, |
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sqlite3_value **argv |
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){ |
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const char *aOrig; int nOrig; /* old blob */ |
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const char *aNew; int nNew; /* new blob */ |
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char *aOut; int nOut; /* output delta */ |
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assert( argc==2 ); |
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if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return; |
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if( sqlite3_value_type(argv[1])==SQLITE_NULL ) return; |
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nOrig = sqlite3_value_bytes(argv[0]); |
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aOrig = (const char*)sqlite3_value_blob(argv[0]); |
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nNew = sqlite3_value_bytes(argv[1]); |
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aNew = (const char*)sqlite3_value_blob(argv[1]); |
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aOut = sqlite3_malloc64(nNew+70); |
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if( aOut==0 ){ |
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sqlite3_result_error_nomem(context); |
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}else{ |
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nOut = delta_create(aOrig, nOrig, aNew, nNew, aOut); |
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if( nOut<0 ){ |
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sqlite3_free(aOut); |
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sqlite3_result_error(context, "cannot create fossil delta", -1); |
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}else{ |
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sqlite3_result_blob(context, aOut, nOut, sqlite3_free); |
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} |
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} |
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} |
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/* |
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** SQL functions: delta_apply(X,D) |
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** |
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** Return the result of applying delta D to input X. |
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*/ |
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static void deltaApplyFunc( |
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sqlite3_context *context, |
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int argc, |
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sqlite3_value **argv |
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){ |
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const char *aOrig; int nOrig; /* The X input */ |
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const char *aDelta; int nDelta; /* The input delta (D) */ |
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char *aOut; int nOut, nOut2; /* The output */ |
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assert( argc==2 ); |
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if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return; |
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if( sqlite3_value_type(argv[1])==SQLITE_NULL ) return; |
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nOrig = sqlite3_value_bytes(argv[0]); |
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aOrig = (const char*)sqlite3_value_blob(argv[0]); |
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nDelta = sqlite3_value_bytes(argv[1]); |
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aDelta = (const char*)sqlite3_value_blob(argv[1]); |
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/* Figure out the size of the output */ |
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nOut = delta_output_size(aDelta, nDelta); |
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if( nOut<0 ){ |
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sqlite3_result_error(context, "corrupt fossil delta", -1); |
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return; |
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} |
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aOut = sqlite3_malloc64((sqlite3_int64)nOut+1); |
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if( aOut==0 ){ |
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sqlite3_result_error_nomem(context); |
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}else{ |
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nOut2 = delta_apply(aOrig, nOrig, aDelta, nDelta, aOut); |
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if( nOut2!=nOut ){ |
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sqlite3_free(aOut); |
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sqlite3_result_error(context, "corrupt fossil delta", -1); |
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}else{ |
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sqlite3_result_blob(context, aOut, nOut, sqlite3_free); |
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} |
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} |
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} |
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/* |
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** SQL functions: delta_output_size(D) |
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** |
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** Return the size of the output that results from applying delta D. |
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*/ |
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static void deltaOutputSizeFunc( |
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sqlite3_context *context, |
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int argc, |
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sqlite3_value **argv |
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){ |
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const char *aDelta; int nDelta; /* The input delta (D) */ |
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int nOut; /* Size of output */ |
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assert( argc==1 ); |
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if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return; |
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nDelta = sqlite3_value_bytes(argv[0]); |
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aDelta = (const char*)sqlite3_value_blob(argv[0]); |
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/* Figure out the size of the output */ |
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nOut = delta_output_size(aDelta, nDelta); |
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if( nOut<0 ){ |
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sqlite3_result_error(context, "corrupt fossil delta", -1); |
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return; |
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}else{ |
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sqlite3_result_int(context, nOut); |
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} |
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} |
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/***************************************************************************** |
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** Table-valued SQL function: delta_parse(DELTA) |
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** |
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** Schema: |
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** |
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** CREATE TABLE delta_parse( |
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** op TEXT, |
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** a1 INT, |
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** a2 ANY, |
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** delta HIDDEN BLOB |
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** ); |
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** |
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** Given an input DELTA, this function parses the delta and returns |
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** rows for each entry in the delta. The op column has one of the |
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** values SIZE, COPY, INSERT, CHECKSUM, ERROR. |
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** |
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** Assuming no errors, the first row has op='SIZE'. a1 is the size of |
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** the output in bytes and a2 is NULL. |
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** |
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** After the initial SIZE row, there are zero or more 'COPY' and/or 'INSERT' |
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** rows. A COPY row means content is copied from the source into the |
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** output. Column a1 is the number of bytes to copy and a2 is the offset |
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** into source from which to begin copying. An INSERT row means to |
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** insert text into the output stream. Column a1 is the number of bytes |
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** to insert and column is a BLOB that contains the text to be inserted. |
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** |
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** The last row of a well-formed delta will have an op value of 'CHECKSUM'. |
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** The a1 column will be the value of the checksum and a2 will be NULL. |
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** |
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** If the input delta is not well-formed, then a row with an op value |
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** of 'ERROR' is returned. The a1 value of the ERROR row is the offset |
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** into the delta where the error was encountered and a2 is NULL. |
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*/ |
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typedef struct deltaparsevtab_vtab deltaparsevtab_vtab; |
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typedef struct deltaparsevtab_cursor deltaparsevtab_cursor; |
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struct deltaparsevtab_vtab { |
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sqlite3_vtab base; /* Base class - must be first */ |
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/* No additional information needed */ |
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}; |
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struct deltaparsevtab_cursor { |
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sqlite3_vtab_cursor base; /* Base class - must be first */ |
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char *aDelta; /* The delta being parsed */ |
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int nDelta; /* Number of bytes in the delta */ |
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int iCursor; /* Current cursor location */ |
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int eOp; /* Name of current operator */ |
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unsigned int a1, a2; /* Arguments to current operator */ |
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int iNext; /* Next cursor value */ |
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}; |
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/* Operator names: |
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*/ |
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static const char *const azOp[] = { |
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"SIZE", "COPY", "INSERT", "CHECKSUM", "ERROR", "EOF" |
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}; |
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#define DELTAPARSE_OP_SIZE 0 |
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#define DELTAPARSE_OP_COPY 1 |
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#define DELTAPARSE_OP_INSERT 2 |
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#define DELTAPARSE_OP_CHECKSUM 3 |
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#define DELTAPARSE_OP_ERROR 4 |
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#define DELTAPARSE_OP_EOF 5 |
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/* |
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** Read bytes from *pz and convert them into a positive integer. When |
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** finished, leave *pz pointing to the first character past the end of |
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** the integer. The *pLen parameter holds the length of the string |
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** in *pz and is decremented once for each character in the integer. |
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*/ |
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static unsigned int deltaGetInt(const char **pz, int *pLen){ |
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static const signed char zValue[] = { |
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, |
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-1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, |
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25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, -1, -1, -1, -1, 36, |
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-1, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, |
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52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, -1, -1, -1, 63, -1, |
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}; |
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unsigned int v = 0; |
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int c; |
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unsigned char *z = (unsigned char*)*pz; |
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unsigned char *zStart = z; |
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while( (c = zValue[0x7f&*(z++)])>=0 ){ |
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v = (v<<6) + c; |
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} |
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z--; |
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*pLen -= z - zStart; |
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*pz = (char*)z; |
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return v; |
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} |
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/* |
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** The deltaparsevtabConnect() method is invoked to create a new |
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** deltaparse virtual table. |
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** |
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** Think of this routine as the constructor for deltaparsevtab_vtab objects. |
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** |
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** All this routine needs to do is: |
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** |
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** (1) Allocate the deltaparsevtab_vtab object and initialize all fields. |
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** |
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** (2) Tell SQLite (via the sqlite3_declare_vtab() interface) what the |
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** result set of queries against the virtual table will look like. |
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*/ |
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static int deltaparsevtabConnect( |
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sqlite3 *db, |
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void *pAux, |
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int argc, const char *const*argv, |
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sqlite3_vtab **ppVtab, |
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char **pzErr |
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){ |
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deltaparsevtab_vtab *pNew; |
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int rc; |
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rc = sqlite3_declare_vtab(db, |
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"CREATE TABLE x(op,a1,a2,delta HIDDEN)" |
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); |
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/* For convenience, define symbolic names for the index to each column. */ |
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#define DELTAPARSEVTAB_OP 0 |
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#define DELTAPARSEVTAB_A1 1 |
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#define DELTAPARSEVTAB_A2 2 |
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#define DELTAPARSEVTAB_DELTA 3 |
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if( rc==SQLITE_OK ){ |
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pNew = sqlite3_malloc64( sizeof(*pNew) ); |
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*ppVtab = (sqlite3_vtab*)pNew; |
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if( pNew==0 ) return SQLITE_NOMEM; |
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memset(pNew, 0, sizeof(*pNew)); |
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sqlite3_vtab_config(db, SQLITE_VTAB_INNOCUOUS); |
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} |
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return rc; |
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} |
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260
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|
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261
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/* |
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262
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** This method is the destructor for deltaparsevtab_vtab objects. |
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263
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*/ |
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264
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static int deltaparsevtabDisconnect(sqlite3_vtab *pVtab){ |
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deltaparsevtab_vtab *p = (deltaparsevtab_vtab*)pVtab; |
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266
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sqlite3_free(p); |
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267
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return SQLITE_OK; |
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} |
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269
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|
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270
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/* |
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271
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** Constructor for a new deltaparsevtab_cursor object. |
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*/ |
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static int deltaparsevtabOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){ |
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deltaparsevtab_cursor *pCur; |
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pCur = sqlite3_malloc( sizeof(*pCur) ); |
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if( pCur==0 ) return SQLITE_NOMEM; |
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memset(pCur, 0, sizeof(*pCur)); |
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278
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*ppCursor = &pCur->base; |
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279
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return SQLITE_OK; |
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280
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} |
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281
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|
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282
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/* |
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283
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** Destructor for a deltaparsevtab_cursor. |
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284
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*/ |
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285
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static int deltaparsevtabClose(sqlite3_vtab_cursor *cur){ |
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286
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deltaparsevtab_cursor *pCur = (deltaparsevtab_cursor*)cur; |
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287
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sqlite3_free(pCur->aDelta); |
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288
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sqlite3_free(pCur); |
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289
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return SQLITE_OK; |
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290
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} |
|
291
|
|
|
292
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|
|
293
|
/* |
|
294
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** Advance a deltaparsevtab_cursor to its next row of output. |
|
295
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*/ |
|
296
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static int deltaparsevtabNext(sqlite3_vtab_cursor *cur){ |
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297
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deltaparsevtab_cursor *pCur = (deltaparsevtab_cursor*)cur; |
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298
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const char *z; |
|
299
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int i = 0; |
|
300
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301
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pCur->iCursor = pCur->iNext; |
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302
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if( pCur->iCursor >= pCur->nDelta ){ |
|
303
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pCur->eOp = DELTAPARSE_OP_ERROR; |
|
304
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pCur->iNext = pCur->nDelta; |
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305
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return SQLITE_OK; |
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306
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} |
|
307
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z = pCur->aDelta + pCur->iCursor; |
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308
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pCur->a1 = deltaGetInt(&z, &i); |
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309
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switch( z[0] ){ |
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310
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case '@': { |
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311
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z++; |
|
312
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if( pCur->iNext>=pCur->nDelta ){ |
|
313
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pCur->eOp = DELTAPARSE_OP_ERROR; |
|
314
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pCur->iNext = pCur->nDelta; |
|
315
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break; |
|
316
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} |
|
317
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pCur->a2 = deltaGetInt(&z, &i); |
|
318
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pCur->eOp = DELTAPARSE_OP_COPY; |
|
319
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pCur->iNext = (int)(&z[1] - pCur->aDelta); |
|
320
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break; |
|
321
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} |
|
322
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case ':': { |
|
323
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z++; |
|
324
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pCur->a2 = (unsigned int)(z - pCur->aDelta); |
|
325
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pCur->eOp = DELTAPARSE_OP_INSERT; |
|
326
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pCur->iNext = (int)(&z[pCur->a1] - pCur->aDelta); |
|
327
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break; |
|
328
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} |
|
329
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case ';': { |
|
330
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pCur->eOp = DELTAPARSE_OP_CHECKSUM; |
|
331
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pCur->iNext = pCur->nDelta; |
|
332
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break; |
|
333
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} |
|
334
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default: { |
|
335
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if( pCur->iNext==pCur->nDelta ){ |
|
336
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pCur->eOp = DELTAPARSE_OP_EOF; |
|
337
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}else{ |
|
338
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pCur->eOp = DELTAPARSE_OP_ERROR; |
|
339
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pCur->iNext = pCur->nDelta; |
|
340
|
} |
|
341
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break; |
|
342
|
} |
|
343
|
} |
|
344
|
return SQLITE_OK; |
|
345
|
} |
|
346
|
|
|
347
|
/* |
|
348
|
** Return values of columns for the row at which the deltaparsevtab_cursor |
|
349
|
** is currently pointing. |
|
350
|
*/ |
|
351
|
static int deltaparsevtabColumn( |
|
352
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sqlite3_vtab_cursor *cur, /* The cursor */ |
|
353
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sqlite3_context *ctx, /* First argument to sqlite3_result_...() */ |
|
354
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int i /* Which column to return */ |
|
355
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){ |
|
356
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deltaparsevtab_cursor *pCur = (deltaparsevtab_cursor*)cur; |
|
357
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switch( i ){ |
|
358
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case DELTAPARSEVTAB_OP: { |
|
359
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sqlite3_result_text(ctx, azOp[pCur->eOp], -1, SQLITE_STATIC); |
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360
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break; |
|
361
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} |
|
362
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case DELTAPARSEVTAB_A1: { |
|
363
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sqlite3_result_int(ctx, pCur->a1); |
|
364
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break; |
|
365
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} |
|
366
|
case DELTAPARSEVTAB_A2: { |
|
367
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if( pCur->eOp==DELTAPARSE_OP_COPY ){ |
|
368
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sqlite3_result_int(ctx, pCur->a2); |
|
369
|
}else if( pCur->eOp==DELTAPARSE_OP_INSERT ){ |
|
370
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if( pCur->a2 + pCur->a1 > pCur->nDelta ){ |
|
371
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sqlite3_result_zeroblob(ctx, pCur->a1); |
|
372
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}else{ |
|
373
|
sqlite3_result_blob(ctx, pCur->aDelta+pCur->a2, pCur->a1, |
|
374
|
SQLITE_TRANSIENT); |
|
375
|
} |
|
376
|
} |
|
377
|
break; |
|
378
|
} |
|
379
|
case DELTAPARSEVTAB_DELTA: { |
|
380
|
sqlite3_result_blob(ctx, pCur->aDelta, pCur->nDelta, SQLITE_TRANSIENT); |
|
381
|
break; |
|
382
|
} |
|
383
|
} |
|
384
|
return SQLITE_OK; |
|
385
|
} |
|
386
|
|
|
387
|
/* |
|
388
|
** Return the rowid for the current row. In this implementation, the |
|
389
|
** rowid is the same as the output value. |
|
390
|
*/ |
|
391
|
static int deltaparsevtabRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){ |
|
392
|
deltaparsevtab_cursor *pCur = (deltaparsevtab_cursor*)cur; |
|
393
|
*pRowid = pCur->iCursor; |
|
394
|
return SQLITE_OK; |
|
395
|
} |
|
396
|
|
|
397
|
/* |
|
398
|
** Return TRUE if the cursor has been moved off of the last |
|
399
|
** row of output. |
|
400
|
*/ |
|
401
|
static int deltaparsevtabEof(sqlite3_vtab_cursor *cur){ |
|
402
|
deltaparsevtab_cursor *pCur = (deltaparsevtab_cursor*)cur; |
|
403
|
return pCur->eOp==DELTAPARSE_OP_EOF || pCur->iCursor>=pCur->nDelta; |
|
404
|
} |
|
405
|
|
|
406
|
/* |
|
407
|
** This method is called to "rewind" the deltaparsevtab_cursor object back |
|
408
|
** to the first row of output. This method is always called at least |
|
409
|
** once prior to any call to deltaparsevtabColumn() or deltaparsevtabRowid() or |
|
410
|
** deltaparsevtabEof(). |
|
411
|
*/ |
|
412
|
static int deltaparsevtabFilter( |
|
413
|
sqlite3_vtab_cursor *pVtabCursor, |
|
414
|
int idxNum, const char *idxStr, |
|
415
|
int argc, sqlite3_value **argv |
|
416
|
){ |
|
417
|
deltaparsevtab_cursor *pCur = (deltaparsevtab_cursor *)pVtabCursor; |
|
418
|
const char *a; |
|
419
|
int i = 0; |
|
420
|
pCur->eOp = DELTAPARSE_OP_ERROR; |
|
421
|
if( idxNum!=1 ){ |
|
422
|
return SQLITE_OK; |
|
423
|
} |
|
424
|
pCur->nDelta = sqlite3_value_bytes(argv[0]); |
|
425
|
a = (const char*)sqlite3_value_blob(argv[0]); |
|
426
|
if( pCur->nDelta==0 || a==0 ){ |
|
427
|
return SQLITE_OK; |
|
428
|
} |
|
429
|
pCur->aDelta = sqlite3_malloc64( pCur->nDelta+1 ); |
|
430
|
if( pCur->aDelta==0 ){ |
|
431
|
pCur->nDelta = 0; |
|
432
|
return SQLITE_NOMEM; |
|
433
|
} |
|
434
|
memcpy(pCur->aDelta, a, pCur->nDelta); |
|
435
|
pCur->aDelta[pCur->nDelta] = 0; |
|
436
|
a = pCur->aDelta; |
|
437
|
pCur->eOp = DELTAPARSE_OP_SIZE; |
|
438
|
pCur->a1 = deltaGetInt(&a, &i); |
|
439
|
if( a[0]!='\n' ){ |
|
440
|
pCur->eOp = DELTAPARSE_OP_ERROR; |
|
441
|
pCur->a1 = pCur->a2 = 0; |
|
442
|
pCur->iNext = pCur->nDelta; |
|
443
|
return SQLITE_OK; |
|
444
|
} |
|
445
|
a++; |
|
446
|
pCur->iNext = (unsigned int)(a - pCur->aDelta); |
|
447
|
return SQLITE_OK; |
|
448
|
} |
|
449
|
|
|
450
|
/* |
|
451
|
** SQLite will invoke this method one or more times while planning a query |
|
452
|
** that uses the virtual table. This routine needs to create |
|
453
|
** a query plan for each invocation and compute an estimated cost for that |
|
454
|
** plan. |
|
455
|
*/ |
|
456
|
static int deltaparsevtabBestIndex( |
|
457
|
sqlite3_vtab *tab, |
|
458
|
sqlite3_index_info *pIdxInfo |
|
459
|
){ |
|
460
|
int i; |
|
461
|
for(i=0; i<pIdxInfo->nConstraint; i++){ |
|
462
|
if( pIdxInfo->aConstraint[i].iColumn != DELTAPARSEVTAB_DELTA ) continue; |
|
463
|
if( pIdxInfo->aConstraint[i].usable==0 ) continue; |
|
464
|
if( pIdxInfo->aConstraint[i].op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue; |
|
465
|
pIdxInfo->aConstraintUsage[i].argvIndex = 1; |
|
466
|
pIdxInfo->aConstraintUsage[i].omit = 1; |
|
467
|
pIdxInfo->estimatedCost = (double)1; |
|
468
|
pIdxInfo->estimatedRows = 10; |
|
469
|
pIdxInfo->idxNum = 1; |
|
470
|
return SQLITE_OK; |
|
471
|
} |
|
472
|
pIdxInfo->idxNum = 0; |
|
473
|
pIdxInfo->estimatedCost = (double)0x7fffffff; |
|
474
|
pIdxInfo->estimatedRows = 0x7fffffff; |
|
475
|
return SQLITE_CONSTRAINT; |
|
476
|
} |
|
477
|
|
|
478
|
/* |
|
479
|
** This following structure defines all the methods for the |
|
480
|
** virtual table. |
|
481
|
*/ |
|
482
|
static sqlite3_module deltaparsevtabModule = { |
|
483
|
/* iVersion */ 0, |
|
484
|
/* xCreate */ 0, |
|
485
|
/* xConnect */ deltaparsevtabConnect, |
|
486
|
/* xBestIndex */ deltaparsevtabBestIndex, |
|
487
|
/* xDisconnect */ deltaparsevtabDisconnect, |
|
488
|
/* xDestroy */ 0, |
|
489
|
/* xOpen */ deltaparsevtabOpen, |
|
490
|
/* xClose */ deltaparsevtabClose, |
|
491
|
/* xFilter */ deltaparsevtabFilter, |
|
492
|
/* xNext */ deltaparsevtabNext, |
|
493
|
/* xEof */ deltaparsevtabEof, |
|
494
|
/* xColumn */ deltaparsevtabColumn, |
|
495
|
/* xRowid */ deltaparsevtabRowid, |
|
496
|
/* xUpdate */ 0, |
|
497
|
/* xBegin */ 0, |
|
498
|
/* xSync */ 0, |
|
499
|
/* xCommit */ 0, |
|
500
|
/* xRollback */ 0, |
|
501
|
/* xFindMethod */ 0, |
|
502
|
/* xRename */ 0, |
|
503
|
/* xSavepoint */ 0, |
|
504
|
/* xRelease */ 0, |
|
505
|
/* xRollbackTo */ 0, |
|
506
|
/* xShadowName */ 0, |
|
507
|
/* xIntegrity */ 0 |
|
508
|
}; |
|
509
|
|
|
510
|
/* |
|
511
|
** Invoke this routine to register the various delta functions. |
|
512
|
*/ |
|
513
|
int deltafunc_init(sqlite3 *db){ |
|
514
|
int rc = SQLITE_OK; |
|
515
|
rc = sqlite3_create_function(db, "delta_create", 2, SQLITE_UTF8, 0, |
|
516
|
deltaCreateFunc, 0, 0); |
|
517
|
if( rc==SQLITE_OK ){ |
|
518
|
rc = sqlite3_create_function(db, "delta_apply", 2, SQLITE_UTF8, 0, |
|
519
|
deltaApplyFunc, 0, 0); |
|
520
|
} |
|
521
|
if( rc==SQLITE_OK ){ |
|
522
|
rc = sqlite3_create_function(db, "delta_output_size", 1, SQLITE_UTF8, 0, |
|
523
|
deltaOutputSizeFunc, 0, 0); |
|
524
|
} |
|
525
|
if( rc==SQLITE_OK ){ |
|
526
|
rc = sqlite3_create_module(db, "delta_parse", &deltaparsevtabModule, 0); |
|
527
|
} |
|
528
|
return rc; |
|
529
|
} |
|
530
|
|