gecko/js/src/jskwgen.cpp

461 lines
13 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set sw=4 ts=8 et tw=80:
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is String Switch Generator for JavaScript Keywords,
* released 2005-12-09.
*
* The Initial Developer of the Original Code is
* Igor Bukanov.
* Portions created by the Initial Developer are Copyright (C) 2005-2006
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#include <stddef.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <ctype.h>
#include "jsversion.h"
const char * const keyword_list[] = {
#define JS_KEYWORD(keyword, type, op, version) #keyword,
#include "jskeyword.tbl"
#undef JS_KEYWORD
};
struct gen_opt {
FILE *output; /* output file for generated source */
unsigned use_if_threshold; /* max number of choices to generate
"if" selector instead of "switch" */
unsigned char_tail_test_threshold; /* max number of unprocessed columns
to use inlined char compare
for remaining chars and not generic
string compare code */
unsigned indent_level; /* current source identation level */
};
static unsigned column_to_compare;
static int
length_comparator(const void *a, const void *b)
{
const char *str1 = keyword_list[*(unsigned *)a];
const char *str2 = keyword_list[*(unsigned *)b];
return (int)strlen(str1) - (int)strlen(str2);
}
static int
column_comparator(const void *a, const void *b)
{
const char *str1 = keyword_list[*(unsigned *)a];
const char *str2 = keyword_list[*(unsigned *)b];
return (int)str1[column_to_compare] - (int)str2[column_to_compare];
}
static unsigned
count_different_lengths(unsigned indexes[], unsigned nelem)
{
unsigned nlength, current_length, i, l;
current_length = 0;
nlength = 0;
for (i = 0; i != nelem; ++i) {
l = (unsigned)strlen(keyword_list[indexes[i]]);
assert(l != 0);
if (current_length != l) {
++nlength;
current_length = l;
}
}
return nlength;
}
static void
find_char_span_and_count(unsigned indexes[], unsigned nelem, unsigned column,
unsigned *span_result, unsigned *count_result)
{
unsigned i, count;
unsigned char c, prev, minc, maxc;
assert(nelem != 0);
minc = maxc = prev = (unsigned char)keyword_list[indexes[0]][column];
count = 1;
for (i = 1; i != nelem; ++i) {
c = (unsigned char)keyword_list[indexes[i]][column];
if (prev != c) {
prev = c;
++count;
if (minc > c) {
minc = c;
} else if (maxc < c) {
maxc = c;
}
}
}
*span_result = maxc - minc + 1;
*count_result = count;
}
static unsigned
find_optimal_switch_column(struct gen_opt *opt,
unsigned indexes[], unsigned nelem,
unsigned columns[], unsigned unprocessed_columns,
int *use_if_result)
{
unsigned i;
unsigned span, min_span, min_span_index;
unsigned nchar, min_nchar, min_nchar_index;
assert(unprocessed_columns != 0);
i = 0;
min_nchar = min_span = (unsigned)-1;
min_nchar_index = min_span_index = 0;
do {
column_to_compare = columns[i];
qsort(indexes, nelem, sizeof(indexes[0]), column_comparator);
find_char_span_and_count(indexes, nelem, column_to_compare,
&span, &nchar);
assert(span != 0);
if (span == 1) {
assert(nchar == 1);
*use_if_result = 1;
return 1;
}
assert(nchar != 1);
if (min_span > span) {
min_span = span;
min_span_index = i;
}
if (min_nchar > nchar) {
min_nchar = nchar;
min_nchar_index = i;
}
} while (++i != unprocessed_columns);
if (min_nchar <= opt->use_if_threshold) {
*use_if_result = 1;
i = min_nchar_index;
} else {
*use_if_result = 0;
i = min_span_index;
}
/*
* Restore order corresponding to i if it was destroyed by
* subsequent sort.
*/
if (i != unprocessed_columns - 1) {
column_to_compare = columns[i];
qsort(indexes, nelem, sizeof(indexes[0]), column_comparator);
}
return i;
}
static void
p(struct gen_opt *opt, const char *format, ...)
{
va_list ap;
va_start(ap, format);
vfprintf(opt->output, format, ap);
va_end(ap);
}
/* Size for '\xxx' where xxx is octal escape */
#define MIN_QUOTED_CHAR_BUFFER 7
static char *
qchar(char c, char *quoted_buffer)
{
char *s;
s = quoted_buffer;
*s++ = '\'';
switch (c) {
case '\n': c = 'n'; goto one_char_escape;
case '\r': c = 'r'; goto one_char_escape;
case '\t': c = 't'; goto one_char_escape;
case '\f': c = 't'; goto one_char_escape;
case '\0': c = '0'; goto one_char_escape;
case '\'': goto one_char_escape;
one_char_escape:
*s++ = '\\';
break;
default:
if (!isprint(c)) {
*s++ = '\\';
*s++ = (char)('0' + (0x3 & (((unsigned char)c) >> 6)));
*s++ = (char)('0' + (0x7 & (((unsigned char)c) >> 3)));
c = (char)('0' + (0x7 & ((unsigned char)c)));
}
}
*s++ = c;
*s++ = '\'';
*s = '\0';
assert(s + 1 <= quoted_buffer + MIN_QUOTED_CHAR_BUFFER);
return quoted_buffer;
}
static void
nl(struct gen_opt *opt)
{
putc('\n', opt->output);
}
static void
indent(struct gen_opt *opt)
{
unsigned n = opt->indent_level;
while (n != 0) {
--n;
fputs(" ", opt->output);
}
}
static void
line(struct gen_opt *opt, const char *format, ...)
{
va_list ap;
indent(opt);
va_start(ap, format);
vfprintf(opt->output, format, ap);
va_end(ap);
nl(opt);
}
static void
generate_letter_switch_r(struct gen_opt *opt,
unsigned indexes[], unsigned nelem,
unsigned columns[], unsigned unprocessed_columns)
{
char qbuf[MIN_QUOTED_CHAR_BUFFER];
assert(nelem != 0);
if (nelem == 1) {
unsigned kw_index = indexes[0];
const char *keyword = keyword_list[kw_index];
if (unprocessed_columns == 0) {
line(opt, "JSKW_GOT_MATCH(%u) /* %s */", kw_index, keyword);
} else if (unprocessed_columns > opt->char_tail_test_threshold) {
line(opt, "JSKW_TEST_GUESS(%u) /* %s */", kw_index, keyword);
} else {
unsigned i, column;
indent(opt); p(opt, "if (");
for (i = 0; i != unprocessed_columns; ++i) {
column = columns[i];
qchar(keyword[column], qbuf);
p(opt, "%sJSKW_AT(%u)==%s", (i == 0) ? "" : " && ",
column, qbuf);
}
p(opt, ") {"); nl(opt);
++opt->indent_level;
line(opt, "JSKW_GOT_MATCH(%u) /* %s */", kw_index, keyword);
--opt->indent_level;
line(opt, "}");
line(opt, "JSKW_NO_MATCH()");
}
} else {
unsigned optimal_column_index, optimal_column;
unsigned i;
int use_if;
char current;
assert(unprocessed_columns != 0);
optimal_column_index = find_optimal_switch_column(opt, indexes, nelem,
columns,
unprocessed_columns,
&use_if);
optimal_column = columns[optimal_column_index];
columns[optimal_column_index] = columns[unprocessed_columns - 1];
if (!use_if)
line(opt, "switch (JSKW_AT(%u)) {", optimal_column);
current = keyword_list[indexes[0]][optimal_column];
for (i = 0; i != nelem;) {
unsigned same_char_begin = i;
char next = current;
for (++i; i != nelem; ++i) {
next = keyword_list[indexes[i]][optimal_column];
if (next != current)
break;
}
qchar(current, qbuf);
if (use_if) {
line(opt, "if (JSKW_AT(%u) == %s) {", optimal_column, qbuf);
} else {
line(opt, " case %s:", qbuf);
}
++opt->indent_level;
generate_letter_switch_r(opt, indexes + same_char_begin,
i - same_char_begin,
columns, unprocessed_columns - 1);
--opt->indent_level;
if (use_if) {
line(opt, "}");
}
current = next;
}
if (!use_if) {
line(opt, "}");
}
columns[optimal_column_index] = optimal_column;
line(opt, "JSKW_NO_MATCH()");
}
}
static void
generate_letter_switch(struct gen_opt *opt,
unsigned indexes[], unsigned nelem,
unsigned current_length)
{
unsigned *columns;
unsigned i;
columns = (unsigned *) malloc(sizeof(columns[0]) * current_length);
if (!columns) {
perror("malloc");
exit(EXIT_FAILURE);
}
for (i = 0; i != current_length; ++i) {
columns[i] = i;
}
generate_letter_switch_r(opt, indexes, nelem, columns, current_length);
free(columns);
}
static void
generate_switch(struct gen_opt *opt)
{
unsigned *indexes;
unsigned nlength;
unsigned i, current;
int use_if;
unsigned nelem;
nelem = sizeof(keyword_list)/sizeof(keyword_list[0]);
line(opt, "/*");
line(opt, " * Generating switch for the list of %u entries:", nelem);
for (i = 0; i != nelem; ++i) {
line(opt, " * %s", keyword_list[i]);
}
line(opt, " */");
indexes = (unsigned *) malloc(sizeof(indexes[0]) * nelem);
if (!indexes) {
perror("malloc");
exit(EXIT_FAILURE);
}
for (i = 0; i != nelem; ++i)
indexes[i] = i;
qsort(indexes, nelem, sizeof(indexes[i]), length_comparator);
nlength = count_different_lengths(indexes, nelem);
use_if = (nlength <= opt->use_if_threshold);
if (!use_if)
line(opt, "switch (JSKW_LENGTH()) {");
current = (unsigned)strlen(keyword_list[indexes[0]]);
for (i = 0; i != nelem;) {
unsigned same_length_begin = i;
unsigned next = current;
for (++i; i != nelem; ++i) {
next = (unsigned)strlen(keyword_list[indexes[i]]);
if (next != current)
break;
}
if (use_if) {
line(opt, "if (JSKW_LENGTH() == %u) {", current);
} else {
line(opt, " case %u:", current);
}
++opt->indent_level;
generate_letter_switch(opt, indexes + same_length_begin,
i - same_length_begin,
current);
--opt->indent_level;
if (use_if) {
line(opt, "}");
}
current = next;
}
if (!use_if)
line(opt, "}");
line(opt, "JSKW_NO_MATCH()");
free(indexes);
}
int main(int argc, char **argv)
{
struct gen_opt opt;
if (argc < 2) {
opt.output = stdout;
} else {
opt.output = fopen(argv[1], "w");
if (!opt.output) {
perror("fopen");
exit(EXIT_FAILURE);
}
}
opt.indent_level = 1;
opt.use_if_threshold = 3;
opt.char_tail_test_threshold = 4;
generate_switch(&opt);
if (opt.output != stdout) {
if (fclose(opt.output)) {
perror("fclose");
exit(EXIT_FAILURE);
}
}
return EXIT_SUCCESS;
}