116 lines
2.6 KiB
C
116 lines
2.6 KiB
C
#include <stdio.h>
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#include <string.h>
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#include <assert.h>
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int flush_lnbuff(void);
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int getch_lnbuff(void);
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void ignoreln_lnbuff(void);
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/* find: prints lines containing pattern, returns number of matching lines
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* gracefully handle line overflow
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* compile with -O3 */
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int find(const char *pattern, char lineno_flag, char except_flag)
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{
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extern long lineno;
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int c, found = 0;
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const char * const pstart = pattern;
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while ((c = getch_lnbuff()) != EOF) {
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if (c == *pattern) {
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pattern++;
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continue;
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}
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char match = !*pattern - (c == '\n');
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match *= except_flag ? -1 : 1;
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if (match < 0 && except_flag) // no match
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ignoreln_lnbuff();
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else if (match > 0) { // match
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found++;
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if (lineno_flag)
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printf("%ld:", lineno);
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flush_lnbuff();
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}
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pattern = pstart;
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}
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return found;
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}
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/* ------------------------ line buffer ---------------------- */
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#define LNBUFF_LEN 1024
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/* the line buffer lenght must be a power of two */
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static_assert(!(LNBUFF_LEN % 2), "Line buffer length is not a power of two!");
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long lineno;
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/* line_buffer: global overflowing line buffer */
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struct {
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char self[LNBUFF_LEN];
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unsigned len;
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char newline;
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} lnbuff = {.len=0, .newline=1};
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/* LNBUFF_I: current index in line buffer */
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#define LNBUFF_I (lnbuff.len & (LNBUFF_LEN - 1))
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/* getch_lnbuff: getchar and add it to buffer */
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int getch_lnbuff()
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{
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int c = getchar();
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if (lnbuff.newline) {
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lnbuff.len = 0;
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lnbuff.newline = 0;
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lineno++;
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}
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if (c == EOF || c == '\n') // new line
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lnbuff.newline = 1;
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else {
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lnbuff.self[LNBUFF_I] = c;
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lnbuff.len++;
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}
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return c;
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}
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/* flush_lnbuff: print contents of line buffer, return length */
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int flush_lnbuff()
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{
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int i;
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/* handle overflowing chars */
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if (lnbuff.len > LNBUFF_LEN) {
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for (i = LNBUFF_LEN; i < lnbuff.len; i++)
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putchar('.');
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for (i = LNBUFF_I; i < LNBUFF_LEN; i++)
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putchar(lnbuff.self[i]);
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}
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/* handle rest of chars */
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for (i = 0; i < LNBUFF_I; i++)
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putchar(lnbuff.self[i]);
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/* print unbuffered part of line */
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if (!lnbuff.newline)
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while ((i = getchar()) != EOF && i != '\n')
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putchar(i);
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putchar('\n');
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lnbuff.newline = 1;
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return lnbuff.len;
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}
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/* ignoreln_lnbuff: ignore line of input */
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void ignoreln_lnbuff()
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{
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int c;
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if (lnbuff.newline)
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return;
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while ((c = getchar()) != EOF && c != '\n')
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;
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lnbuff.newline = 1;
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}
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