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https://github.com/tursodatabase/libsql.git
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d3a156caf5
A common complain with libSQL is how to run extensions. The main mechanism, with a .so, has a lot of issues around how those .so are distributed. The most common extensions are the ones in the sqlean package. We can improve this experience by bundling them in our sqlite build. Not all SQLean extensions are kosher: some of them, like fileio, use the vfs. Others, are deemed too complex. The extensions included here are a subset that we deem important enough, and low risk enough, to just be a part of the main bundle.
116 lines
2.6 KiB
C
116 lines
2.6 KiB
C
// Copyright (c) 2014 Ross Bayer, MIT License
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// https://github.com/Rostepher/libstrcmp
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#include <assert.h>
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#include <ctype.h>
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#include <stdlib.h>
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#include <string.h>
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#include "fuzzy/common.h"
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/// Helper function that returns the numeric code for a given char as specified
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/// by the soundex algorithm.
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///
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/// @param c char to encode
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///
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/// @returns char representation of the number associated with the given char
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static char soundex_encode(const char c) {
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switch (tolower(c)) {
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case 'b':
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case 'f':
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case 'p':
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case 'v':
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return '1';
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case 'c':
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case 'g':
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case 'j':
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case 'k':
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case 'q':
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case 's':
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case 'x':
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case 'z':
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return '2';
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case 'd':
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case 't':
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return '3';
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case 'l':
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return '4';
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case 'm':
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case 'n':
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return '5';
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case 'r':
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return '6';
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default:
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break;
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}
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return '0';
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}
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/// Computes and returns the soundex representation of a given non NULL string.
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/// More information about the algorithm can be found here:
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/// https://en.wikipedia.org/wiki/Soundex
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///
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/// @param str non NULL string to encode
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///
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/// @returns soundex representation of str
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char* soundex(const char* str) {
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// string cannot be NULL
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assert(str != NULL);
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size_t str_len = strlen(str);
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// allocate space for final code and null terminator
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char* code = malloc(5 * sizeof(char));
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// temporary buffer to encode string
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char* buf = malloc((str_len + 1) * sizeof(char));
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// set first value to first char in str
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code[0] = toupper(str[0]);
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// number of digits in code
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unsigned d = 1;
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// encode all chars in str
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for (unsigned i = 0; i < str_len; i++) {
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buf[i] = soundex_encode(str[i]);
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}
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// add all viable chars to code
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for (unsigned i = 1; i < str_len && d < 4; i++) {
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// check if current char in buf is not the same as previous char
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// and that the current char is not '0'
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if (NOT_EQ(buf[i], buf[i - 1]) && NOT_EQ(buf[i], '0')) {
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// if digits separated by an 'h' or 'w' are the same, skip them
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if (i > 1 && EQ(buf[i], buf[i - 2]) && strchr("hw", str[i - 1])) {
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continue;
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}
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// add digit to the code
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code[d] = buf[i];
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// increment digit counter
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d++;
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}
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}
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// pad the end of code with '0' if too short
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while (d < 4) {
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code[d] = '0';
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d++;
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}
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// null terminate string
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code[d] = '\0';
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free(buf);
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return code;
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}
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