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| # include <cstdio>
# include <cstdlib>
# include <cstring>
# include <cstdarg>
# include <cctype>
const int MAX_TOKEN=30;
const char EOL='\n';
class token_db {
static token_db* db;
private:
int m_count;
char** m_table;
int m_seq;
token_db() : m_count(0), m_table(NULL), m_seq(0) {}
token_db(const token_db&);
~token_db() {}
public:
void install (int count, char** table) {
m_count = count;
m_table = table;
}
bool match_expected (char* key) {
if (!strcmp (key, m_table[m_seq]))
return true;
return false;
}
int get_seq() { return m_seq; }
void clear_seq() { m_seq = 0; }
void next_seq() { m_seq++; }
bool last_seq() { return (m_seq == m_count) ? true : false; }
bool lookup (char* key) {
for (int i = 0; i < m_count; i++)
if (!strcmp(key, m_table[i]))
return true;
return false;
}
static token_db* get_instance() {
if (db == NULL) {
db = new token_db();
}
return db;
}
};
token_db *token_db::db = NULL;
void fatal(char* fmt, ...)
{
va_list args;
va_start(args, fmt);
vfprintf(stderr, fmt, args);
exit (EXIT_FAILURE);
}
class buffer {
private:
char *m_buffer;
int m_size;
char *m_ptr;
char *m_eob;
public:
buffer(int size) : m_size(size) {
m_buffer = new char[size];
m_ptr = m_buffer;
m_eob = m_buffer + size;
}
~buffer() {
delete m_buffer;
}
void zero() { m_ptr = m_buffer; }
void put(char ch) {
*m_ptr++ = ch;
if (m_ptr == m_eob)
fatal("*** buffer overflow\n");
}
void put (char* s) {
while (*s != 0)
put(*s);
}
void flush() {
fwrite(m_buffer, sizeof(char), m_ptr - m_buffer, stdout);
zero();
}
void putfmt(char* fmt, ...)
{
va_list args;
va_start(args, fmt);
int length = vsnprintf(m_ptr, m_eob - m_ptr, fmt, args);
if (length == -1)
fatal("*** buffer overflow\n");
m_ptr += length;
}
};
char get_token (char* token, int max)
{
char ch;
while (max > 0) {
ch = fgetc(stdin);
switch (ch) {
case '>' : *token = 0;
case EOF : return ch;
default: *token++ = ch; max--;
}
}
fatal ("*** token buffer overflow\n");
}
void parse_input (char* token, bool filter, buffer* p_buf)
{
char ch;
char new_token[MAX_TOKEN];
bool match;
token_db* db = token_db::get_instance();
while (1) {
if ( (ch = fgetc(stdin)) == EOF) {
if (token != NULL)
fatal ("***got EOF while parsing %s\n", token);
return;
}
if (ch == '<') {
if (token != NULL) {
ch = fgetc(stdin);
if (ch != '/')
ungetc(ch, stdin);
else {
ch = get_token (new_token, MAX_TOKEN);
if (!strcmp (token, new_token)) {
if (filter == true) {
p_buf->putfmt("</%s>\n", token);
}
if (db->match_expected(new_token)) {
db->next_seq();
if (db->last_seq()) {
p_buf->flush();
db->clear_seq();
}
}
return;
} else
fatal("*** closing %s does not match opened %s\n",
new_token, token);
}
}
if ( get_token (new_token, MAX_TOKEN) == EOF)
fatal ("*** got EOF while parsing %s\n", token);
match = db->match_expected(new_token);
if (filter || match)
p_buf->putfmt("<%s>", new_token);
if (!match) {
p_buf->zero();
db->clear_seq();
} else
parse_input (new_token, (match) ? true : filter, p_buf);
} else {
if (filter == true)
p_buf->put(ch);
else if (db->get_seq() > 0 && isgraph(ch)) {
p_buf->zero();
db->clear_seq();
}
}
}
}
int main (int argc, char **argv)
{
buffer p_buf(512);
token_db* db = token_db::get_instance();
db->install (argc - 1, &argv[1]);
parse_input (NULL, false, &p_buf);
return EXIT_SUCCESS;
} |
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