input.c

pl0编译器

/*
 *	Parse a makefile
 */


#include "h.h"


struct name		namehead;
struct name *		firstname;

char 			str1[LZ];		/*  General store  */
char			str2[LZ];


/*
 *	Intern a name.  Return a pointer to the name struct
 */
struct name *
newname(name)
char *			name;
{
	register struct name *	rp;
	register struct name *	rrp;


	for
	(
		rp = namehead.n_next, rrp = &namehead;
		rp;
		rp = rp->n_next, rrp = rrp->n_next
	)
		if (strcmp(name, rp->n_name) == 0)
			return rp;

	if ((rp = (struct name *)malloc(sizeof (struct name)))
				== (struct name *)0)
		fatal("No memory for name");
	rrp->n_next = rp;
	rp->n_next = (struct name *)0;

	if ((rp->n_name = strdup(name)) == NULL)
		fatal("No memory for name '%s'",name);

	rp->n_line = (struct line *)0;
	rp->n_time = (time_t)0;
	rp->n_flag = 0;

	return rp;
}


/*
 *	Add a dependant to the end of the supplied list of dependants.
 *	Return the new head pointer for that list.
 */
struct depend *
newdep(np, dp)
struct name *		np;
struct depend *		dp;
{
	register struct depend *	rp;
	register struct depend *	rrp;


	if ((rp = (struct depend *)malloc(sizeof (struct depend)))
				== (struct depend *)0)
		fatal("No memory for dependant");
	rp->d_next = (struct depend *)0;
	rp->d_name = np;

	if (dp == (struct depend *)0)
		return rp;

	for (rrp = dp; rrp->d_next; rrp = rrp->d_next)
		;

	rrp->d_next = rp;

	return dp;
}


/*
 *	Add a command to the end of the supplied list of commands.
 *	Return the new head pointer for that list.
 */
struct cmd *
newcmd(str, cp)
char *			str;
struct cmd *		cp;
{
	register struct cmd *	rp;
	register struct cmd *	rrp;
	register char *		rcp;


	if (rcp = strrchr(str, '\n'))
		*rcp = '\0';		/*  Loose newline  */

	while (isspace(*str))
		str++;

	if (*str == '\0')		/*  If nothing left, the exit  */
		return NULL;

	if ((rp = (struct cmd *)malloc(sizeof (struct cmd)))
				== (struct cmd *)0)
		fatal("No memory for command");
	rp->c_next = (struct cmd *)0;

	if ((rp->c_cmd = strdup(str)) == NULL)
		fatal("No memory for command '%s'",str);

	if (cp == (struct cmd *)0)
		return rp;

	for (rrp = cp; rrp->c_next; rrp = rrp->c_next)
		;

	rrp->c_next = rp;

	return cp;
}


/*
 *	Add a new 'line' of stuff to a target.  This check to see
 *	if commands already exist for the target.  If flag is set,
 *	the line is a double colon target.
 *
 *	Kludges:
 *	i)  If the new name begins with a '.', and there are no dependents,
 *	    then the target must cease to be a target.  This is for .SUFFIXES.
 *	ii) If the new name begins with a '.', with no dependents and has
 *	    commands, then replace the current commands.  This is for
 *	    redefining commands for a default rule.
 *	Neither of these free the space used by dependents or commands,
 *	since they could be used by another target.
 */
void
newline(np, dp, cp, flag)
struct name *		np;
struct depend *		dp;
struct cmd *		cp;
{
	bool			hascmds = FALSE;  /*  Target has commands  */
	register struct line *	rp;
	register struct line *	rrp;


	/* Handle the .SUFFIXES case */
	if (np->n_name[0] == '.' && !dp && !cp)
	{
		for (rp = np->n_line; rp; rp = rrp)
		{
			rrp = rp->l_next;
			free(rp);
		}
		np->n_line = (struct line *)0;
		np->n_flag &= ~N_TARG;
		return;
	}

	/* This loop must happen since rrp is used later. */
	for
	(
		rp = np->n_line, rrp = (struct line *)0;
		rp;
		rrp = rp, rp = rp->l_next
	)
		if (rp->l_cmd)
			hascmds = TRUE;

	if (hascmds && cp && !(np->n_flag & N_DOUBLE))
		/* Handle the implicit rules redefinition case */
		if (np->n_name[0] == '.' && dp == (struct depend *)0)
		{
			np->n_line->l_cmd = cp;
			return;
		}
		else
			error("Commands defined twice for target %s", np->n_name);
	if (np->n_flag & N_TARG)
		if (!(np->n_flag & N_DOUBLE) != !flag)		/* like xor */
			error("Inconsistent rules for target %s", np->n_name);

	if ((rp = (struct line *)malloc(sizeof (struct line)))
				== (struct line *)0)
		fatal("No memory for line");
	rp->l_next = (struct line *)0;
	rp->l_dep = dp;
	rp->l_cmd = cp;

	if (rrp)
		rrp->l_next = rp;
	else
		np->n_line = rp;

	np->n_flag |= N_TARG;
	if (flag)
		np->n_flag |= N_DOUBLE;
}


/*
 *	Parse input from the makefile, and construct a tree structure
 *	of it.
 */
void input(FILE *fd)
{
  char *			p;		/*  General  */
  char *			q;
  struct name *		np;
  struct depend *		dp;
  struct cmd *		cp;
  bool			dbl;
  
  
  if (getline(str1, fd))	/*  Read the first line  */
    return;
  
  for(;;)
    {
      if (*str1 == '\t')	/*  Rules without targets  */
	error("Rules not allowed here");
      
      p = str1;
      
      while (isspace(*p))	/*  Find first target  */
	p++;
      
      while (((q = strchr(p, '=')) != (char *)0) &&
	     (p != q) && (q[-1] == '\\'))	/*  Find value */
	{
	  register char *		a;
	  
	  a = q - 1;	/*  Del \ chr; move rest back  */
	  p = q;
	  while(*a++ = *q++)
	    ;
	}
      
      if (q != (char *)0)
	{
	  register char *		a;
	  
	  *q++ = '\0';		/*  Separate name and val  */
	  while (isspace(*q))
	    q++;
	  if (p = strrchr(q, '\n'))
	    *p = '\0';
	  
	  p = str1;
	  if ((a = gettok(&p)) == (char *)0)
	    error("No macro name");
	  
	  setmacro(a, q);
	  
	  if (getline(str1, fd))
	    return;
	  continue;
	}
      
      expand(str1);
      p = str1;
      
      while (((q = strchr(p, ':')) != (char *)0) &&
	     (p != q) && (q[-1] == '\\'))	/*  Find dependents  */
	{
	  register char *		a;
	  
	  a = q - 1;	/*  Del \ chr; move rest back  */
	  p = q;
	  while(*a++ = *q++)
	    ;
	}
      
      if (q == (char *)0)
	error("No targets provided");
      
      *q++ = '\0';	/*  Separate targets and dependents  */
      
      if (*q == ':')		/* Double colon */
	{
	  dbl = 1;
	  q++;
	}
      else
	dbl = 0;
      
      for (dp = (struct depend *)0; ((p = gettok(&q)) != (char *)0);)
	/*  get list of dep's */
	{
	  np = newname(p);		/*  Intern name  */
	  dp = newdep(np, dp);		/*  Add to dep list */
	}
      
      *((q = str1) + strlen(str1) + 1) = '\0';
      /*  Need two nulls for gettok (Remember separation)  */
      
      cp = (struct cmd *)0;
      if (getline(str2, fd) == FALSE)		/*  Get commands  */
	{
	  while (*str2 == '\t')
	    {
	      cp = newcmd(&str2[0], cp);
	      if (getline(str2, fd))
		break;
	    }
	}
      
      while ((p = gettok(&q)) != (char *)0)	/* Get list of targ's */
	{
	  np = newname(p);		/*  Intern name  */
	  newline(np, dp, cp, dbl);
	  if (!firstname && p[0] != '.')
	    firstname = np;
	}
      
      if (feof(fd))				/*  EOF?  */
	return;
      
      strcpy(str1, str2);
    }
}