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Alternative way of writing (part of) the arithmetic lexical analyzer

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- committed separately to make it easier to swap back if desired.

This version avoids open coding is_name() and isdigit() - measurements
show it is perhaps fractionally faster (though the difference is so small
as to probably be statistically insignifigant - if I were a statician
I might understand that) and just a little larger than the previous version.
This commit is contained in:
kre 2017-03-20 11:31:00 +00:00
parent cc8e58edf3
commit 4d6f79f52d
1 changed files with 32 additions and 29 deletions
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61
bin/sh/arith_token.c
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@ -1,4 +1,4 @@
/* $NetBSD: arith_token.c,v 1.1 2017/03/20 11:26:07 kre Exp $ */
/* $NetBSD: arith_token.c,v 1.2 2017/03/20 11:31:00 kre Exp $ */
/*-
* Copyright (c) 2002
@ -39,7 +39,7 @@
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: arith_token.c,v 1.1 2017/03/20 11:26:07 kre Exp $");
__RCSID("$NetBSD: arith_token.c,v 1.2 2017/03/20 11:31:00 kre Exp $");
#endif /* not lint */
#include <inttypes.h>
@ -79,7 +79,36 @@ arith_token(void)
for (;;) {
token = *buf;
switch (token) {
if (isdigit(token)) {
/*
* Numbers all start with a digit, and nothing
* else does, the number ends wherever
* strtoimax() stops...
*/
a_t_val.val = strtoimax(buf, &end, 0);
arith_buf = end;
return ARITH_NUM;
} else if (is_name(token) {
/*
* Variable names all start with an alpha (or '_')
* and nothing else does. They continue for the
* longest unbroken sequence of alphanumerics ( + _ )
*/
p = buf;
while (buf++, is_in_name(*buf))
;
a_t_val.name = stalloc(buf - p + 1);
memcpy(a_t_val.name, p, buf - p);
a_t_val.name[buf - p] = '\0';
arith_buf = buf;
return ARITH_VAR;
} else switch (token) {
/*
* everything else must be some kind of
* operator, white space, or an error.
*/
case ' ':
case '\t':
case '\n':
@ -91,32 +120,6 @@ arith_token(void)
token, token);
/* NOTREACHED */
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
a_t_val.val = strtoimax(buf, &end, 0);
arith_buf = end;
return ARITH_NUM;
case 'A': case 'B': case 'C': case 'D': case 'E':
case 'F': case 'G': case 'H': case 'I': case 'J':
case 'K': case 'L': case 'M': case 'N': case 'O':
case 'P': case 'Q': case 'R': case 'S': case 'T':
case 'U': case 'V': case 'W': case 'X': case 'Y': case 'Z':
case 'a': case 'b': case 'c': case 'd': case 'e':
case 'f': case 'g': case 'h': case 'i': case 'j':
case 'k': case 'l': case 'm': case 'n': case 'o':
case 'p': case 'q': case 'r': case 's': case 't':
case 'u': case 'v': case 'w': case 'x': case 'y': case 'z':
case '_':
p = buf;
while (buf++, is_in_name(*buf))
;
a_t_val.name = stalloc(buf - p + 1);
memcpy(a_t_val.name, p, buf - p);
a_t_val.name[buf - p] = '\0';
arith_buf = buf;
return ARITH_VAR;
case '=':
token = ARITH_ASS;
checkeq: