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wc: goto considered harmful

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* src/wc.c: Do not include assure.h.  Replace the only
use of ‘assure’ with ‘unreachable’ which is good enough.
(wc, main): Remove labels and gotos.  This doesn’t affect
performance in any way I can measure, and makes the code
a bit easier to follow.
This commit is contained in:
Paul Eggert
2023-09-23 17:07:33 -07:00
parent 6b8b1f9e77
commit f40c6b5cf2
1 changed files with 55 additions and 47 deletions
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102
src/wc.c
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@@ -25,7 +25,6 @@
#include <sys/types.h>
#include <uchar.h>
#include <assure.h>
#include <argmatch.h>
#include <argv-iter.h>
#include <fadvise.h>
@@ -497,37 +496,46 @@ wc (int fd, char const *file_x, struct fstatus *fstatus, off_t current_pos)
if (linepos > linelength)
linelength = linepos;
linepos = 0;
goto mb_word_separator;
in_word = false;
break;
case '\t':
linepos += 8 - (linepos % 8);
goto mb_word_separator;
in_word = false;
break;
case ' ':
linepos++;
FALLTHROUGH;
case '\v':
mb_word_separator:
in_word = false;
break;
default:
/* c32width can be expensive on macOS for example,
so avoid if not needed. */
default:;
bool in_word2;
if (single_byte)
linepos += wc_isprint[wide_char];
else if (print_linelength)
{
int width = c32width (wide_char);
if (width > 0)
linepos += width;
linepos += wc_isprint[wide_char];
in_word2 = !wc_isspace[wide_char];
}
else
{
/* c32width can be expensive on macOS for example,
so avoid if not needed. */
if (print_linelength)
{
int width = c32width (wide_char);
if (width > 0)
linepos += width;
}
in_word2 = !iswnbspace (wide_char);
}
if (single_byte ? wc_isspace[wide_char]
: c32isspace (wide_char) || iswnbspace (wide_char))
goto mb_word_separator;
/* Count words by counting word starts, i.e., each
white space character (or the start of input)
followed by non white space. */
words += !in_word;
in_word = true;
words += !in_word & in_word2;
in_word = in_word2;
break;
}
@@ -567,23 +575,26 @@ wc (int fd, char const *file_x, struct fstatus *fstatus, off_t current_pos)
if (linepos > linelength)
linelength = linepos;
linepos = 0;
goto word_separator;
in_word = false;
break;
case '\t':
linepos += 8 - (linepos % 8);
goto word_separator;
in_word = false;
break;
case ' ':
linepos++;
FALLTHROUGH;
case '\v':
word_separator:
in_word = false;
break;
default:
linepos += wc_isprint[c];
if (wc_isspace[c])
goto word_separator;
words += !in_word;
in_word = true;
bool in_word2 = !wc_isspace[c];
words += !in_word & in_word2;
in_word = in_word2;
break;
}
}
@@ -711,7 +722,6 @@ compute_number_width (idx_t nfiles, struct fstatus const *fstatus)
int
main (int argc, char **argv)
{
bool ok;
int optc;
idx_t nfiles;
char **files;
@@ -858,29 +868,12 @@ main (int argc, char **argv)
else
number_width = compute_number_width (nfiles, fstatus);
ok = true;
for (int i = 0; /* */; i++)
bool ok = true;
enum argv_iter_err ai_err;
char *file_name;
for (int i = 0; (file_name = argv_iter (ai, &ai_err)); i++)
{
bool skip_file = false;
enum argv_iter_err ai_err;
char *file_name = argv_iter (ai, &ai_err);
if (!file_name)
{
switch (ai_err)
{
case AI_ERR_EOF:
goto argv_iter_done;
case AI_ERR_READ:
error (0, errno, _("%s: read error"),
quotef (files_from));
ok = false;
goto argv_iter_done;
case AI_ERR_MEM:
xalloc_die ();
default:
affirm (!"unexpected error code from argv_iter");
}
}
if (files_from && STREQ (files_from, "-") && STREQ (file_name, "-"))
{
/* Give a better diagnostic in an unusual case:
@@ -918,7 +911,22 @@ main (int argc, char **argv)
if (! nfiles)
fstatus[0].failed = 1;
}
argv_iter_done:
switch (ai_err)
{
case AI_ERR_EOF:
break;
case AI_ERR_READ:
error (0, errno, _("%s: read error"), quotef (files_from));
ok = false;
break;
case AI_ERR_MEM:
xalloc_die ();
default:
unreachable ();
}
/* No arguments on the command line is fine. That means read from stdin.
However, no arguments on the --files0-from input stream is an error