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887 lines
26 KiB
887 lines
26 KiB
/*
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** 2016-05-28
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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******************************************************************************
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**
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** This file contains the implementation of an SQLite virtual table for
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** reading CSV files.
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**
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** Usage:
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**
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** .load ./csv
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** CREATE VIRTUAL TABLE temp.csv USING csv(filename=FILENAME);
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** SELECT * FROM csv;
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**
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** The columns are named "c1", "c2", "c3", ... by default. But the
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** application can define its own CREATE TABLE statement as an additional
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** parameter. For example:
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**
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** CREATE VIRTUAL TABLE temp.csv2 USING csv(
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** filename = "../http.log",
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** schema = "CREATE TABLE x(date,ipaddr,url,referrer,userAgent)"
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** );
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**
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** Instead of specifying a file, the text of the CSV can be loaded using
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** the data= parameter.
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**
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** If the columns=N parameter is supplied, then the CSV file is assumed to have
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** N columns. If the columns parameter is omitted, the CSV file is opened
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** as soon as the virtual table is constructed and the first row of the CSV
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** is read in order to count the tables.
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**
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** Some extra debugging features (used for testing virtual tables) are available
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** if this module is compiled with -DSQLITE_TEST.
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*/
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#include "sqlite3ext.h"
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SQLITE_EXTENSION_INIT1
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#include <string.h>
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#include <stdlib.h>
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#include <assert.h>
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#include <stdarg.h>
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#include <ctype.h>
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#include <stdio.h>
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#ifndef SQLITE_OMIT_VIRTUALTABLE
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/*
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** A macro to hint to the compiler that a function should not be
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** inlined.
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*/
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#if defined(__GNUC__)
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# define CSV_NOINLINE __attribute__((noinline))
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#elif defined(_MSC_VER) && _MSC_VER>=1310
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# define CSV_NOINLINE __declspec(noinline)
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#else
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# define CSV_NOINLINE
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#endif
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/* Max size of the error message in a CsvReader */
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#define CSV_MXERR 200
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/* Size of the CsvReader input buffer */
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#define CSV_INBUFSZ 1024
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/* A context object used when read a CSV file. */
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typedef struct CsvReader CsvReader;
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struct CsvReader {
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FILE *in; /* Read the CSV text from this input stream */
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char *z; /* Accumulated text for a field */
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int n; /* Number of bytes in z */
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int nAlloc; /* Space allocated for z[] */
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int nLine; /* Current line number */
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int bNotFirst; /* True if prior text has been seen */
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int cTerm; /* Character that terminated the most recent field */
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size_t iIn; /* Next unread character in the input buffer */
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size_t nIn; /* Number of characters in the input buffer */
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char *zIn; /* The input buffer */
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char zErr[CSV_MXERR]; /* Error message */
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};
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/* Initialize a CsvReader object */
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static void csv_reader_init(CsvReader *p){
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p->in = 0;
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p->z = 0;
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p->n = 0;
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p->nAlloc = 0;
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p->nLine = 0;
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p->bNotFirst = 0;
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p->nIn = 0;
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p->zIn = 0;
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p->zErr[0] = 0;
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}
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/* Close and reset a CsvReader object */
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static void csv_reader_reset(CsvReader *p){
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if( p->in ){
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fclose(p->in);
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sqlite3_free(p->zIn);
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}
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sqlite3_free(p->z);
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csv_reader_init(p);
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}
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/* Report an error on a CsvReader */
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static void csv_errmsg(CsvReader *p, const char *zFormat, ...){
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va_list ap;
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va_start(ap, zFormat);
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sqlite3_vsnprintf(CSV_MXERR, p->zErr, zFormat, ap);
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va_end(ap);
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}
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/* Open the file associated with a CsvReader
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** Return the number of errors.
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*/
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static int csv_reader_open(
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CsvReader *p, /* The reader to open */
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const char *zFilename, /* Read from this filename */
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const char *zData /* ... or use this data */
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){
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if( zFilename ){
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p->zIn = sqlite3_malloc( CSV_INBUFSZ );
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if( p->zIn==0 ){
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csv_errmsg(p, "out of memory");
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return 1;
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}
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p->in = fopen(zFilename, "rb");
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if( p->in==0 ){
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csv_reader_reset(p);
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csv_errmsg(p, "cannot open '%s' for reading", zFilename);
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return 1;
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}
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}else{
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assert( p->in==0 );
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p->zIn = (char*)zData;
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p->nIn = strlen(zData);
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}
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return 0;
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}
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/* The input buffer has overflowed. Refill the input buffer, then
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** return the next character
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*/
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static CSV_NOINLINE int csv_getc_refill(CsvReader *p){
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size_t got;
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assert( p->iIn>=p->nIn ); /* Only called on an empty input buffer */
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assert( p->in!=0 ); /* Only called if reading froma file */
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got = fread(p->zIn, 1, CSV_INBUFSZ, p->in);
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if( got==0 ) return EOF;
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p->nIn = got;
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p->iIn = 1;
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return p->zIn[0];
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}
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/* Return the next character of input. Return EOF at end of input. */
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static int csv_getc(CsvReader *p){
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if( p->iIn >= p->nIn ){
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if( p->in!=0 ) return csv_getc_refill(p);
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return EOF;
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}
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return ((unsigned char*)p->zIn)[p->iIn++];
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}
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/* Increase the size of p->z and append character c to the end.
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** Return 0 on success and non-zero if there is an OOM error */
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static CSV_NOINLINE int csv_resize_and_append(CsvReader *p, char c){
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char *zNew;
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int nNew = p->nAlloc*2 + 100;
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zNew = sqlite3_realloc64(p->z, nNew);
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if( zNew ){
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p->z = zNew;
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p->nAlloc = nNew;
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p->z[p->n++] = c;
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return 0;
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}else{
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csv_errmsg(p, "out of memory");
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return 1;
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}
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}
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/* Append a single character to the CsvReader.z[] array.
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** Return 0 on success and non-zero if there is an OOM error */
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static int csv_append(CsvReader *p, char c){
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if( p->n>=p->nAlloc-1 ) return csv_resize_and_append(p, c);
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p->z[p->n++] = c;
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return 0;
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}
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/* Read a single field of CSV text. Compatible with rfc4180 and extended
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** with the option of having a separator other than ",".
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**
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** + Input comes from p->in.
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** + Store results in p->z of length p->n. Space to hold p->z comes
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** from sqlite3_malloc64().
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** + Keep track of the line number in p->nLine.
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** + Store the character that terminates the field in p->cTerm. Store
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** EOF on end-of-file.
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**
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** Return "" at EOF. Return 0 on an OOM error.
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*/
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static char *csv_read_one_field(CsvReader *p){
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int c;
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p->n = 0;
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c = csv_getc(p);
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if( c==EOF ){
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p->cTerm = EOF;
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return "";
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}
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if( c=='"' ){
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int pc, ppc;
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int startLine = p->nLine;
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pc = ppc = 0;
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while( 1 ){
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c = csv_getc(p);
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if( c<='"' || pc=='"' ){
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if( c=='\n' ) p->nLine++;
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if( c=='"' ){
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if( pc=='"' ){
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pc = 0;
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continue;
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}
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}
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if( (c==',' && pc=='"')
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|| (c=='\n' && pc=='"')
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|| (c=='\n' && pc=='\r' && ppc=='"')
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|| (c==EOF && pc=='"')
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){
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do{ p->n--; }while( p->z[p->n]!='"' );
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p->cTerm = (char)c;
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break;
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}
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if( pc=='"' && c!='\r' ){
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csv_errmsg(p, "line %d: unescaped %c character", p->nLine, '"');
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break;
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}
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if( c==EOF ){
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csv_errmsg(p, "line %d: unterminated %c-quoted field\n",
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startLine, '"');
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p->cTerm = (char)c;
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break;
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}
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}
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if( csv_append(p, (char)c) ) return 0;
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ppc = pc;
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pc = c;
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}
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}else{
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/* If this is the first field being parsed and it begins with the
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** UTF-8 BOM (0xEF BB BF) then skip the BOM */
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if( (c&0xff)==0xef && p->bNotFirst==0 ){
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csv_append(p, (char)c);
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c = csv_getc(p);
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if( (c&0xff)==0xbb ){
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csv_append(p, (char)c);
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c = csv_getc(p);
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if( (c&0xff)==0xbf ){
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p->bNotFirst = 1;
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p->n = 0;
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return csv_read_one_field(p);
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}
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}
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}
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while( c>',' || (c!=EOF && c!=',' && c!='\n') ){
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if( csv_append(p, (char)c) ) return 0;
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c = csv_getc(p);
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}
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if( c=='\n' ){
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p->nLine++;
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if( p->n>0 && p->z[p->n-1]=='\r' ) p->n--;
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}
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p->cTerm = (char)c;
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}
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if( p->z ) p->z[p->n] = 0;
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p->bNotFirst = 1;
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return p->z;
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}
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/* Forward references to the various virtual table methods implemented
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** in this file. */
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static int csvtabCreate(sqlite3*, void*, int, const char*const*,
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sqlite3_vtab**,char**);
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static int csvtabConnect(sqlite3*, void*, int, const char*const*,
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sqlite3_vtab**,char**);
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static int csvtabBestIndex(sqlite3_vtab*,sqlite3_index_info*);
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static int csvtabDisconnect(sqlite3_vtab*);
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static int csvtabOpen(sqlite3_vtab*, sqlite3_vtab_cursor**);
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static int csvtabClose(sqlite3_vtab_cursor*);
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static int csvtabFilter(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
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int argc, sqlite3_value **argv);
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static int csvtabNext(sqlite3_vtab_cursor*);
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static int csvtabEof(sqlite3_vtab_cursor*);
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static int csvtabColumn(sqlite3_vtab_cursor*,sqlite3_context*,int);
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static int csvtabRowid(sqlite3_vtab_cursor*,sqlite3_int64*);
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/* An instance of the CSV virtual table */
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typedef struct CsvTable {
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sqlite3_vtab base; /* Base class. Must be first */
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char *zFilename; /* Name of the CSV file */
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char *zData; /* Raw CSV data in lieu of zFilename */
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long iStart; /* Offset to start of data in zFilename */
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int nCol; /* Number of columns in the CSV file */
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unsigned int tstFlags; /* Bit values used for testing */
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} CsvTable;
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/* Allowed values for tstFlags */
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#define CSVTEST_FIDX 0x0001 /* Pretend that constrained searchs cost less*/
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/* A cursor for the CSV virtual table */
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typedef struct CsvCursor {
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sqlite3_vtab_cursor base; /* Base class. Must be first */
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CsvReader rdr; /* The CsvReader object */
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char **azVal; /* Value of the current row */
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int *aLen; /* Length of each entry */
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sqlite3_int64 iRowid; /* The current rowid. Negative for EOF */
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} CsvCursor;
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/* Transfer error message text from a reader into a CsvTable */
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static void csv_xfer_error(CsvTable *pTab, CsvReader *pRdr){
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sqlite3_free(pTab->base.zErrMsg);
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pTab->base.zErrMsg = sqlite3_mprintf("%s", pRdr->zErr);
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}
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/*
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** This method is the destructor fo a CsvTable object.
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*/
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static int csvtabDisconnect(sqlite3_vtab *pVtab){
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CsvTable *p = (CsvTable*)pVtab;
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sqlite3_free(p->zFilename);
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sqlite3_free(p->zData);
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sqlite3_free(p);
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return SQLITE_OK;
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}
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/* Skip leading whitespace. Return a pointer to the first non-whitespace
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** character, or to the zero terminator if the string has only whitespace */
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static const char *csv_skip_whitespace(const char *z){
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while( isspace((unsigned char)z[0]) ) z++;
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return z;
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}
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/* Remove trailing whitespace from the end of string z[] */
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static void csv_trim_whitespace(char *z){
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size_t n = strlen(z);
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while( n>0 && isspace((unsigned char)z[n]) ) n--;
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z[n] = 0;
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}
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/* Dequote the string */
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static void csv_dequote(char *z){
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int j;
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char cQuote = z[0];
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size_t i, n;
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if( cQuote!='\'' && cQuote!='"' ) return;
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n = strlen(z);
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if( n<2 || z[n-1]!=z[0] ) return;
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for(i=1, j=0; i<n-1; i++){
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if( z[i]==cQuote && z[i+1]==cQuote ) i++;
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z[j++] = z[i];
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}
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z[j] = 0;
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}
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/* Check to see if the string is of the form: "TAG = VALUE" with optional
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** whitespace before and around tokens. If it is, return a pointer to the
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** first character of VALUE. If it is not, return NULL.
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*/
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static const char *csv_parameter(const char *zTag, int nTag, const char *z){
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z = csv_skip_whitespace(z);
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if( strncmp(zTag, z, nTag)!=0 ) return 0;
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z = csv_skip_whitespace(z+nTag);
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if( z[0]!='=' ) return 0;
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return csv_skip_whitespace(z+1);
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}
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/* Decode a parameter that requires a dequoted string.
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**
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** Return 1 if the parameter is seen, or 0 if not. 1 is returned
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** even if there is an error. If an error occurs, then an error message
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** is left in p->zErr. If there are no errors, p->zErr[0]==0.
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*/
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static int csv_string_parameter(
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CsvReader *p, /* Leave the error message here, if there is one */
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const char *zParam, /* Parameter we are checking for */
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const char *zArg, /* Raw text of the virtual table argment */
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char **pzVal /* Write the dequoted string value here */
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){
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const char *zValue;
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zValue = csv_parameter(zParam,(int)strlen(zParam),zArg);
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if( zValue==0 ) return 0;
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p->zErr[0] = 0;
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if( *pzVal ){
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csv_errmsg(p, "more than one '%s' parameter", zParam);
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return 1;
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}
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*pzVal = sqlite3_mprintf("%s", zValue);
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if( *pzVal==0 ){
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csv_errmsg(p, "out of memory");
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return 1;
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}
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csv_trim_whitespace(*pzVal);
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csv_dequote(*pzVal);
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return 1;
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}
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|
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/* Return 0 if the argument is false and 1 if it is true. Return -1 if
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** we cannot really tell.
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*/
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static int csv_boolean(const char *z){
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if( sqlite3_stricmp("yes",z)==0
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|| sqlite3_stricmp("on",z)==0
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|| sqlite3_stricmp("true",z)==0
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|| (z[0]=='1' && z[1]==0)
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){
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return 1;
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}
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if( sqlite3_stricmp("no",z)==0
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|| sqlite3_stricmp("off",z)==0
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|| sqlite3_stricmp("false",z)==0
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|| (z[0]=='0' && z[1]==0)
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){
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return 0;
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}
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return -1;
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}
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/*
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** Parameters:
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** filename=FILENAME Name of file containing CSV content
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** data=TEXT Direct CSV content.
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** schema=SCHEMA Alternative CSV schema.
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|
** header=YES|NO First row of CSV defines the names of
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|
** columns if "yes". Default "no".
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|
** columns=N Assume the CSV file contains N columns.
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|
**
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|
** Only available if compiled with SQLITE_TEST:
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|
**
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|
** testflags=N Bitmask of test flags. Optional
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|
**
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|
** If schema= is omitted, then the columns are named "c0", "c1", "c2",
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|
** and so forth. If columns=N is omitted, then the file is opened and
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|
** the number of columns in the first row is counted to determine the
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** column count. If header=YES, then the first row is skipped.
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*/
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|
static int csvtabConnect(
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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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CsvTable *pNew = 0; /* The CsvTable object to construct */
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int bHeader = -1; /* header= flags. -1 means not seen yet */
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|
int rc = SQLITE_OK; /* Result code from this routine */
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|
int i, j; /* Loop counters */
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#ifdef SQLITE_TEST
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int tstFlags = 0; /* Value for testflags=N parameter */
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|
#endif
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int nCol = -99; /* Value of the columns= parameter */
|
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CsvReader sRdr; /* A CSV file reader used to store an error
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|
** message and/or to count the number of columns */
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|
static const char *azParam[] = {
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"filename", "data", "schema",
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};
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|
char *azPValue[3]; /* Parameter values */
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|
# define CSV_FILENAME (azPValue[0])
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# define CSV_DATA (azPValue[1])
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# define CSV_SCHEMA (azPValue[2])
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|
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assert( sizeof(azPValue)==sizeof(azParam) );
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memset(&sRdr, 0, sizeof(sRdr));
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memset(azPValue, 0, sizeof(azPValue));
|
|
for(i=3; i<argc; i++){
|
|
const char *z = argv[i];
|
|
const char *zValue;
|
|
for(j=0; j<sizeof(azParam)/sizeof(azParam[0]); j++){
|
|
if( csv_string_parameter(&sRdr, azParam[j], z, &azPValue[j]) ) break;
|
|
}
|
|
if( j<sizeof(azParam)/sizeof(azParam[0]) ){
|
|
if( sRdr.zErr[0] ) goto csvtab_connect_error;
|
|
}else
|
|
if( (zValue = csv_parameter("header",6,z))!=0 ){
|
|
int x;
|
|
if( bHeader>=0 ){
|
|
csv_errmsg(&sRdr, "more than one 'header' parameter");
|
|
goto csvtab_connect_error;
|
|
}
|
|
x = csv_boolean(zValue);
|
|
if( x==1 ){
|
|
bHeader = 1;
|
|
}else if( x==0 ){
|
|
bHeader = 0;
|
|
}else{
|
|
csv_errmsg(&sRdr, "unrecognized argument to 'header': %s", zValue);
|
|
goto csvtab_connect_error;
|
|
}
|
|
}else
|
|
#ifdef SQLITE_TEST
|
|
if( (zValue = csv_parameter("testflags",9,z))!=0 ){
|
|
tstFlags = (unsigned int)atoi(zValue);
|
|
}else
|
|
#endif
|
|
if( (zValue = csv_parameter("columns",7,z))!=0 ){
|
|
if( nCol>0 ){
|
|
csv_errmsg(&sRdr, "more than one 'columns' parameter");
|
|
goto csvtab_connect_error;
|
|
}
|
|
nCol = atoi(zValue);
|
|
if( nCol<=0 ){
|
|
csv_errmsg(&sRdr, "must have at least one column");
|
|
goto csvtab_connect_error;
|
|
}
|
|
}else
|
|
{
|
|
csv_errmsg(&sRdr, "unrecognized parameter '%s'", z);
|
|
goto csvtab_connect_error;
|
|
}
|
|
}
|
|
if( (CSV_FILENAME==0)==(CSV_DATA==0) ){
|
|
csv_errmsg(&sRdr, "must either filename= or data= but not both");
|
|
goto csvtab_connect_error;
|
|
}
|
|
if( nCol<=0 && csv_reader_open(&sRdr, CSV_FILENAME, CSV_DATA) ){
|
|
goto csvtab_connect_error;
|
|
}
|
|
pNew = sqlite3_malloc( sizeof(*pNew) );
|
|
*ppVtab = (sqlite3_vtab*)pNew;
|
|
if( pNew==0 ) goto csvtab_connect_oom;
|
|
memset(pNew, 0, sizeof(*pNew));
|
|
if( nCol>0 ){
|
|
pNew->nCol = nCol;
|
|
}else{
|
|
do{
|
|
const char *z = csv_read_one_field(&sRdr);
|
|
if( z==0 ) goto csvtab_connect_oom;
|
|
pNew->nCol++;
|
|
}while( sRdr.cTerm==',' );
|
|
}
|
|
pNew->zFilename = CSV_FILENAME; CSV_FILENAME = 0;
|
|
pNew->zData = CSV_DATA; CSV_DATA = 0;
|
|
#ifdef SQLITE_TEST
|
|
pNew->tstFlags = tstFlags;
|
|
#endif
|
|
pNew->iStart = bHeader==1 ? ftell(sRdr.in) : 0;
|
|
csv_reader_reset(&sRdr);
|
|
if( CSV_SCHEMA==0 ){
|
|
char *zSep = "";
|
|
CSV_SCHEMA = sqlite3_mprintf("CREATE TABLE x(");
|
|
if( CSV_SCHEMA==0 ) goto csvtab_connect_oom;
|
|
for(i=0; i<pNew->nCol; i++){
|
|
CSV_SCHEMA = sqlite3_mprintf("%z%sc%d TEXT",CSV_SCHEMA, zSep, i);
|
|
zSep = ",";
|
|
}
|
|
CSV_SCHEMA = sqlite3_mprintf("%z);", CSV_SCHEMA);
|
|
}
|
|
rc = sqlite3_declare_vtab(db, CSV_SCHEMA);
|
|
if( rc ) goto csvtab_connect_error;
|
|
for(i=0; i<sizeof(azPValue)/sizeof(azPValue[0]); i++){
|
|
sqlite3_free(azPValue[i]);
|
|
}
|
|
return SQLITE_OK;
|
|
|
|
csvtab_connect_oom:
|
|
rc = SQLITE_NOMEM;
|
|
csv_errmsg(&sRdr, "out of memory");
|
|
|
|
csvtab_connect_error:
|
|
if( pNew ) csvtabDisconnect(&pNew->base);
|
|
for(i=0; i<sizeof(azPValue)/sizeof(azPValue[0]); i++){
|
|
sqlite3_free(azPValue[i]);
|
|
}
|
|
if( sRdr.zErr[0] ){
|
|
sqlite3_free(*pzErr);
|
|
*pzErr = sqlite3_mprintf("%s", sRdr.zErr);
|
|
}
|
|
csv_reader_reset(&sRdr);
|
|
if( rc==SQLITE_OK ) rc = SQLITE_ERROR;
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Reset the current row content held by a CsvCursor.
|
|
*/
|
|
static void csvtabCursorRowReset(CsvCursor *pCur){
|
|
CsvTable *pTab = (CsvTable*)pCur->base.pVtab;
|
|
int i;
|
|
for(i=0; i<pTab->nCol; i++){
|
|
sqlite3_free(pCur->azVal[i]);
|
|
pCur->azVal[i] = 0;
|
|
pCur->aLen[i] = 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
** The xConnect and xCreate methods do the same thing, but they must be
|
|
** different so that the virtual table is not an eponymous virtual table.
|
|
*/
|
|
static int csvtabCreate(
|
|
sqlite3 *db,
|
|
void *pAux,
|
|
int argc, const char *const*argv,
|
|
sqlite3_vtab **ppVtab,
|
|
char **pzErr
|
|
){
|
|
return csvtabConnect(db, pAux, argc, argv, ppVtab, pzErr);
|
|
}
|
|
|
|
/*
|
|
** Destructor for a CsvCursor.
|
|
*/
|
|
static int csvtabClose(sqlite3_vtab_cursor *cur){
|
|
CsvCursor *pCur = (CsvCursor*)cur;
|
|
csvtabCursorRowReset(pCur);
|
|
csv_reader_reset(&pCur->rdr);
|
|
sqlite3_free(cur);
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/*
|
|
** Constructor for a new CsvTable cursor object.
|
|
*/
|
|
static int csvtabOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
|
|
CsvTable *pTab = (CsvTable*)p;
|
|
CsvCursor *pCur;
|
|
size_t nByte;
|
|
nByte = sizeof(*pCur) + (sizeof(char*)+sizeof(int))*pTab->nCol;
|
|
pCur = sqlite3_malloc64( nByte );
|
|
if( pCur==0 ) return SQLITE_NOMEM;
|
|
memset(pCur, 0, nByte);
|
|
pCur->azVal = (char**)&pCur[1];
|
|
pCur->aLen = (int*)&pCur->azVal[pTab->nCol];
|
|
*ppCursor = &pCur->base;
|
|
if( csv_reader_open(&pCur->rdr, pTab->zFilename, pTab->zData) ){
|
|
csv_xfer_error(pTab, &pCur->rdr);
|
|
return SQLITE_ERROR;
|
|
}
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
|
|
/*
|
|
** Advance a CsvCursor to its next row of input.
|
|
** Set the EOF marker if we reach the end of input.
|
|
*/
|
|
static int csvtabNext(sqlite3_vtab_cursor *cur){
|
|
CsvCursor *pCur = (CsvCursor*)cur;
|
|
CsvTable *pTab = (CsvTable*)cur->pVtab;
|
|
int i = 0;
|
|
char *z;
|
|
do{
|
|
z = csv_read_one_field(&pCur->rdr);
|
|
if( z==0 ){
|
|
csv_xfer_error(pTab, &pCur->rdr);
|
|
break;
|
|
}
|
|
if( i<pTab->nCol ){
|
|
if( pCur->aLen[i] < pCur->rdr.n+1 ){
|
|
char *zNew = sqlite3_realloc64(pCur->azVal[i], pCur->rdr.n+1);
|
|
if( zNew==0 ){
|
|
csv_errmsg(&pCur->rdr, "out of memory");
|
|
csv_xfer_error(pTab, &pCur->rdr);
|
|
break;
|
|
}
|
|
pCur->azVal[i] = zNew;
|
|
pCur->aLen[i] = pCur->rdr.n+1;
|
|
}
|
|
memcpy(pCur->azVal[i], z, pCur->rdr.n+1);
|
|
i++;
|
|
}
|
|
}while( pCur->rdr.cTerm==',' );
|
|
if( z==0 || (pCur->rdr.cTerm==EOF && i<pTab->nCol) ){
|
|
pCur->iRowid = -1;
|
|
}else{
|
|
pCur->iRowid++;
|
|
while( i<pTab->nCol ){
|
|
sqlite3_free(pCur->azVal[i]);
|
|
pCur->azVal[i] = 0;
|
|
pCur->aLen[i] = 0;
|
|
i++;
|
|
}
|
|
}
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/*
|
|
** Return values of columns for the row at which the CsvCursor
|
|
** is currently pointing.
|
|
*/
|
|
static int csvtabColumn(
|
|
sqlite3_vtab_cursor *cur, /* The cursor */
|
|
sqlite3_context *ctx, /* First argument to sqlite3_result_...() */
|
|
int i /* Which column to return */
|
|
){
|
|
CsvCursor *pCur = (CsvCursor*)cur;
|
|
CsvTable *pTab = (CsvTable*)cur->pVtab;
|
|
if( i>=0 && i<pTab->nCol && pCur->azVal[i]!=0 ){
|
|
sqlite3_result_text(ctx, pCur->azVal[i], -1, SQLITE_STATIC);
|
|
}
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/*
|
|
** Return the rowid for the current row.
|
|
*/
|
|
static int csvtabRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
|
|
CsvCursor *pCur = (CsvCursor*)cur;
|
|
*pRowid = pCur->iRowid;
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/*
|
|
** Return TRUE if the cursor has been moved off of the last
|
|
** row of output.
|
|
*/
|
|
static int csvtabEof(sqlite3_vtab_cursor *cur){
|
|
CsvCursor *pCur = (CsvCursor*)cur;
|
|
return pCur->iRowid<0;
|
|
}
|
|
|
|
/*
|
|
** Only a full table scan is supported. So xFilter simply rewinds to
|
|
** the beginning.
|
|
*/
|
|
static int csvtabFilter(
|
|
sqlite3_vtab_cursor *pVtabCursor,
|
|
int idxNum, const char *idxStr,
|
|
int argc, sqlite3_value **argv
|
|
){
|
|
CsvCursor *pCur = (CsvCursor*)pVtabCursor;
|
|
CsvTable *pTab = (CsvTable*)pVtabCursor->pVtab;
|
|
pCur->iRowid = 0;
|
|
if( pCur->rdr.in==0 ){
|
|
assert( pCur->rdr.zIn==pTab->zData );
|
|
assert( pTab->iStart>=0 );
|
|
assert( (size_t)pTab->iStart<=pCur->rdr.nIn );
|
|
pCur->rdr.iIn = pTab->iStart;
|
|
}else{
|
|
fseek(pCur->rdr.in, pTab->iStart, SEEK_SET);
|
|
pCur->rdr.iIn = 0;
|
|
pCur->rdr.nIn = 0;
|
|
}
|
|
return csvtabNext(pVtabCursor);
|
|
}
|
|
|
|
/*
|
|
** Only a forward full table scan is supported. xBestIndex is mostly
|
|
** a no-op. If CSVTEST_FIDX is set, then the presence of equality
|
|
** constraints lowers the estimated cost, which is fiction, but is useful
|
|
** for testing certain kinds of virtual table behavior.
|
|
*/
|
|
static int csvtabBestIndex(
|
|
sqlite3_vtab *tab,
|
|
sqlite3_index_info *pIdxInfo
|
|
){
|
|
pIdxInfo->estimatedCost = 1000000;
|
|
#ifdef SQLITE_TEST
|
|
if( (((CsvTable*)tab)->tstFlags & CSVTEST_FIDX)!=0 ){
|
|
/* The usual (and sensible) case is to always do a full table scan.
|
|
** The code in this branch only runs when testflags=1. This code
|
|
** generates an artifical and unrealistic plan which is useful
|
|
** for testing virtual table logic but is not helpful to real applications.
|
|
**
|
|
** Any ==, LIKE, or GLOB constraint is marked as usable by the virtual
|
|
** table (even though it is not) and the cost of running the virtual table
|
|
** is reduced from 1 million to just 10. The constraints are *not* marked
|
|
** as omittable, however, so the query planner should still generate a
|
|
** plan that gives a correct answer, even if they plan is not optimal.
|
|
*/
|
|
int i;
|
|
int nConst = 0;
|
|
for(i=0; i<pIdxInfo->nConstraint; i++){
|
|
unsigned char op;
|
|
if( pIdxInfo->aConstraint[i].usable==0 ) continue;
|
|
op = pIdxInfo->aConstraint[i].op;
|
|
if( op==SQLITE_INDEX_CONSTRAINT_EQ
|
|
|| op==SQLITE_INDEX_CONSTRAINT_LIKE
|
|
|| op==SQLITE_INDEX_CONSTRAINT_GLOB
|
|
){
|
|
pIdxInfo->estimatedCost = 10;
|
|
pIdxInfo->aConstraintUsage[nConst].argvIndex = nConst+1;
|
|
nConst++;
|
|
}
|
|
}
|
|
}
|
|
#endif
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
|
|
static sqlite3_module CsvModule = {
|
|
0, /* iVersion */
|
|
csvtabCreate, /* xCreate */
|
|
csvtabConnect, /* xConnect */
|
|
csvtabBestIndex, /* xBestIndex */
|
|
csvtabDisconnect, /* xDisconnect */
|
|
csvtabDisconnect, /* xDestroy */
|
|
csvtabOpen, /* xOpen - open a cursor */
|
|
csvtabClose, /* xClose - close a cursor */
|
|
csvtabFilter, /* xFilter - configure scan constraints */
|
|
csvtabNext, /* xNext - advance a cursor */
|
|
csvtabEof, /* xEof - check for end of scan */
|
|
csvtabColumn, /* xColumn - read data */
|
|
csvtabRowid, /* xRowid - read data */
|
|
0, /* xUpdate */
|
|
0, /* xBegin */
|
|
0, /* xSync */
|
|
0, /* xCommit */
|
|
0, /* xRollback */
|
|
0, /* xFindMethod */
|
|
0, /* xRename */
|
|
};
|
|
|
|
#ifdef SQLITE_TEST
|
|
/*
|
|
** For virtual table testing, make a version of the CSV virtual table
|
|
** available that has an xUpdate function. But the xUpdate always returns
|
|
** SQLITE_READONLY since the CSV file is not really writable.
|
|
*/
|
|
static int csvtabUpdate(sqlite3_vtab *p,int n,sqlite3_value**v,sqlite3_int64*x){
|
|
return SQLITE_READONLY;
|
|
}
|
|
static sqlite3_module CsvModuleFauxWrite = {
|
|
0, /* iVersion */
|
|
csvtabCreate, /* xCreate */
|
|
csvtabConnect, /* xConnect */
|
|
csvtabBestIndex, /* xBestIndex */
|
|
csvtabDisconnect, /* xDisconnect */
|
|
csvtabDisconnect, /* xDestroy */
|
|
csvtabOpen, /* xOpen - open a cursor */
|
|
csvtabClose, /* xClose - close a cursor */
|
|
csvtabFilter, /* xFilter - configure scan constraints */
|
|
csvtabNext, /* xNext - advance a cursor */
|
|
csvtabEof, /* xEof - check for end of scan */
|
|
csvtabColumn, /* xColumn - read data */
|
|
csvtabRowid, /* xRowid - read data */
|
|
csvtabUpdate, /* xUpdate */
|
|
0, /* xBegin */
|
|
0, /* xSync */
|
|
0, /* xCommit */
|
|
0, /* xRollback */
|
|
0, /* xFindMethod */
|
|
0, /* xRename */
|
|
};
|
|
#endif /* SQLITE_TEST */
|
|
|
|
#endif /* !defined(SQLITE_OMIT_VIRTUALTABLE) */
|
|
|
|
|
|
#ifdef _WIN32
|
|
__declspec(dllexport)
|
|
#endif
|
|
/*
|
|
** This routine is called when the extension is loaded. The new
|
|
** CSV virtual table module is registered with the calling database
|
|
** connection.
|
|
*/
|
|
int sqlite3_csv_init(
|
|
sqlite3 *db,
|
|
char **pzErrMsg,
|
|
const sqlite3_api_routines *pApi
|
|
){
|
|
#ifndef SQLITE_OMIT_VIRTUALTABLE
|
|
int rc;
|
|
SQLITE_EXTENSION_INIT2(pApi);
|
|
rc = sqlite3_create_module(db, "csv", &CsvModule, 0);
|
|
#ifdef SQLITE_TEST
|
|
if( rc==SQLITE_OK ){
|
|
rc = sqlite3_create_module(db, "csv_wr", &CsvModuleFauxWrite, 0);
|
|
}
|
|
#endif
|
|
return rc;
|
|
#else
|
|
return SQLITE_OK;
|
|
#endif
|
|
}
|
|
|