mklatinkbd.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

/*
 * Parse /lib/keyboard to create latin1.h table for kernel.
 * mklatinkbd -r prints an array of integers rather than a Rune string literal.
 */

#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ctype.h>

int rflag;

enum {
	MAXLD = 2,	/* latin1.c assumes this is 2 */
};

char *head = ""
"/*\n"
" * This is automatically generated by %s from /lib/keyboard\n"
" * Edit /lib/keyboard instead.\n"
" */\n";

/*
 * latin1.c assumes that strlen(ld) is at most 2.
 * It also assumes that latintab[i].ld can be a prefix of latintab[j].ld
 * only when j < i.  We ensure this by sorting the output by prefix length.
 * The so array is indexed by the character value.
 */

typedef struct Trie	Trie;
struct Trie {
	int n; /* of characters r */
	char seq[MAXLD+1];
	Rune r[256];
	Trie *link[256];
};

Trie *root;

Trie*
mktrie(char *seq)
{
	uchar *q;
	Trie **tp;

	if(root == nil) {
		root = malloc(sizeof *root);
		memset(root, 0, sizeof *root);
	}

	assert(seq[0] != '\0');

	tp = &root;
	for(q=(uchar*)seq; *(q+1) != '\0'; q++) {
		tp = &(*tp)->link[*q];
		if(*tp == nil) {
			*tp = malloc(sizeof(**tp));
			assert(*tp != nil);
			memset(*tp, 0, sizeof(**tp));
			strcpy((*tp)->seq, seq);
			(*tp)->seq[q+1-(uchar*)seq] = '\0';
		}
	}

	assert(*tp != nil);
	return *tp;
}

/* add character sequence s meaning rune r */
void
insert(char *s, Rune r)
{
	uchar lastc;
	int len;
	Trie *t;

	len = strlen(s);
	lastc = (uchar)s[len-1];

	t = mktrie(s);
	if(t->r[lastc]) {
		fprint(2, "warning: table duplicate: %s is %C and %C\n", s, t->r[lastc], r);
		return;
	}
	t->r[lastc] = r;
	t->n++;
}

void
cprintchar(Biobuf *b, int c)
{
	/* print a byte c safe for a C string. */
	switch(c) {
	case '\'':
	case '\"':
	case '\\':
		Bprint(b, "\\%c", c);
		break;
	case '\t':
		Bprint(b, "\\t");
		break;
	default:
		if(isascii(c) && isprint(c))
			Bprint(b, "%c", c);
		else
			Bprint(b, "\\x%.2x", c);
		break;
	}
}

void
cprints(Biobuf *b, char *p)
{
	while(*p != '\0')
		cprintchar(b, *p++);
}


void
printtrie(Biobuf *b, Trie *t)
{
	int i;

	for(i=0; i<256; i++)
		if(t->link[i])
			printtrie(b, t->link[i]);

	if(t->n > 0) {
		Bprint(b, "\t\"");
		cprints(b, t->seq);
		Bprint(b, "\", \"");
		for(i=0; i<256; i++)
			if(t->r[i])
				cprintchar(b, i);
		Bprint(b, "\",\t");
		if(rflag) {
			Bprint(b, "{");
			for(i=0; i<256; i++)
				if(t->r[i])
					Bprint(b, " 0x%.4ux,", t->r[i]);
			Bprint(b, " }");
		} else {
			Bprint(b, "L\"");
			for(i=0; i<256; i++)
				if(t->r[i])
					Bprint(b, "%C", t->r[i]);
			Bprint(b, "\"");
		}
		Bprint(b, ",\n");
	}	
}

void
readfile(char *fname)
{
	Biobuf *b;
	char *line, *p;
	char *seq;
	int inseq;
	int lineno;
	Rune r;

	if((b = Bopen(fname, OREAD)) == 0) {
		fprint(2, "cannot open \"%s\": %r\n", fname);
		exits("open");
	}

	lineno = 0;
	while((line = Brdline(b, '\n')) != 0) {
		lineno++;
		if(line[0] == '#')
			continue;

		r = strtol(line, nil, 16);
		p = strchr(line, ' ');
		if(r == 0 || p != line+4 || p[0] != ' ' || p[1] != ' ') {
			fprint(2, "%s:%d: cannot parse line\n", fname, lineno);
			continue;
		}

		p = line+6;
/*	00AE  Or rO       ®	registered trade mark sign	*/
		for(inseq=1, seq=p; (uchar)*p < Runeself; p++) {
			if(*p == '\0' || isspace(*p)) {
				if(inseq && p-seq >= 2) {
					*p = '\0';
					inseq = 0;
					insert(seq, r);
					*p = ' ';
				}
				if(*p == '\0')
					break;
			} else {
				if(!inseq) {
					seq = p;
					inseq = 1;
				}
			}
		}
	}
}

void
usage(void)
{
	fprint(2, "usage: mklatinkbd [-r] [/lib/keyboard]\n");
	exits("usage");
}

void
main(int argc, char **argv)
{
	Biobuf bout;

	ARGBEGIN{
	case 'r':	/* print rune values */
		rflag = 1;
		break;
	default:
		usage();
	}ARGEND

	if(argc > 1)
		usage();

	readfile(argc == 1 ? argv[0] : "/fd/0");

	Binit(&bout, 1, OWRITE);
	if(root)
		printtrie(&bout, root);
	exits(0);
}