path: root/5.19.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#define MAXTOKEN	100
#define OUTLEN		1000
#define MAXBUFF		100

enum { NAME, PARENS, BRACKETS };
enum { NO, YES };

void err(char *s);

int gettoken(void);
int peaktoken(void);
char tokentype;
char token[MAXTOKEN];
char prevtoken;
char out[OUTLEN];

char buff[MAXBUFF];
static size_t top;


void err(char *s)
{
	printf("fatal error: %s\n", s);
	exit(1);
}

int gettoken(void)
{
	char c, *p = token;
	char getch(void);
	void ungetch(char);

	if (prevtoken == YES) {
		prevtoken = NO;
		return tokentype;
	}

	while(isblank(c = getch()))
		;

	if (c == '/') { /* ignore comments */
		if ((c = getch()) == '/') {
			while ((c = getch()) != '\n')
				;
		} else if (c == '*') {
			while (getch() != '*' || (c = getch()) != '/')
				if (c == '*')
					ungetch('*');
			return gettoken();
		} else {
			ungetch(c);
			c = '/';
		}
	}

	if (c == '(') {
		if ((c = getch()) == ')') {
			strcpy(token, "()");
			return tokentype = PARENS;
		} else {
			ungetch(c);
			return tokentype = '(';
		}
	} else if (c == '[') {
		for (*p++ = '['; (*p++ = getch()) != ']';)
			;
		*p = '\0';
		return tokentype = BRACKETS;
	} else if (isalpha(c)) {
		for (*p++ = c; isalnum(c = getch());)
			*p++ = c;
		*p = '\0';
		ungetch(c);
		return tokentype = NAME;
	} else {
		return tokentype = c;
	}
}

void ungetch(char c)
{
	if (top < MAXBUFF)
		buff[top++] = c;
	else
		err("buff: stack overflow");
}

char getch(void)
{
	return (top > 0) ? buff[--top] : getchar();
}

int peaktoken()
{
	char type;

	type = gettoken();
	prevtoken = YES;
	return type;
}

int main(void)
{
	int err;
	char type;
	char temp[OUTLEN + MAXTOKEN];

	while (gettoken() != EOF) {
		err = 0;
		strcpy(out, token);
		while ((type = gettoken()) != '\n') {
			if (type == PARENS || type == BRACKETS ) {
				strcat(out, token);
			} else if (type == '*') {
				if ((type = peaktoken()) == PARENS ||
					type == BRACKETS)
					sprintf(temp, "(*%s)", out);
				else
					sprintf(temp, "*%s", out);
				strcpy(out, temp);
			} else if (type == NAME) {
				sprintf(temp, "%s %s", token, out);
				out[0] = '\0'; /* rust sisters btfo */
				strncat(out, temp, OUTLEN - 1);
			} else {
				err = 1;
				printf("err: invalid input at %s\n", token);
				while ((type = gettoken()) != '\n')
					;
				ungetch('\n');
			}
		}

		if (!err)
			printf("%s\n", out);
	}

	return 0;
}