mined2.c

操作系统源代码

  		do {
  			subs++;	/* Increment subs */
  			if ((textp = substitute(line, program,replacement))
								     == NIL_PTR)
  				return;	/* Line too long */
  		} while ((program->status & BEGIN_LINE) != BEGIN_LINE &&
			 (program->status & END_LINE) != END_LINE &&
					  line_check(program, textp, FORWARD));
  		/* Check to see if we can print the result */
  		if (page <= screenmax) {
  			set_cursor(0, page);
  			line_print(line);
  		}
  	}
  	if (page <= screenmax)
  		page++;
  	line = line->next;
  } while (line != tail && file == VALID && quit == FALSE);

  copy_string(mess_buf, (quit == TRUE) ? "(Aborted) " : "");
/* Fix the status line */
  if (subs == 0L && quit == FALSE)
  	error("Pattern not found.", NIL_PTR);
  else if (lines >= REPORT || quit == TRUE) {
  	build_string(mess_buf, "%s %D substitutions on %D lines.", mess_buf,
								   subs, lines);
  	status_line(mess_buf, NIL_PTR);
  }
  else if (file == NOT_VALID && subs >= REPORT)
  	status_line(num_out(subs), " substitutions.");
  else
  	clear_status();
  move_to (x, y);
}

/*
 * Substitute() replaces the match on this line by the substitute pattern
 * as indicated by the program. Every '&' in the replacement is replaced by 
 * the original match. A \ in the replacement escapes the next character.
 */
char *substitute(line, program, replacement)
LINE *line;
REGEX *program;
char *replacement;		/* Contains replacement pattern */
{
  register char *textp = text_buffer;
  register char *subp = replacement;
  char *linep = line->text;
  char *amp;

  modified = TRUE;

/* Copy part of line until the beginning of the match */
  while (linep != program->start_ptr)
  	*textp++ = *linep++;
  
/*
 * Replace the match by the substitution pattern. Each occurrence of '&' is
 * replaced by the original match. A \ escapes the next character.
 */
  while (*subp != '\0' && textp < &text_buffer[MAX_CHARS]) {
  	if (*subp == '&') {		/* Replace the original match */
  		amp = program->start_ptr;
  		while (amp < program->end_ptr && textp<&text_buffer[MAX_CHARS])
  			*textp++ = *amp++;
  		subp++;
  	}
  	else {
  		if (*subp == '\\' && *(subp + 1) != '\0')
  			subp++;
  		*textp++ = *subp++;
  	}
  }

/* Check for line length not exceeding MAX_CHARS */
  if (length_of(text_buffer) + length_of(program->end_ptr) >= MAX_CHARS) {
  	error("Substitution result: line too big", NIL_PTR);
  	return NIL_PTR;
  }

/* Append last part of line to the new build line */
  copy_string(textp, program->end_ptr);

/* Free old line and install new one */
  free_space(line->text);
  line->text = alloc(length_of(text_buffer) + 1);
  copy_string(line->text, text_buffer);

  return(line->text + (textp - text_buffer));
}

/*
 * Search() calls get_expression to fetch the expression. If this went well,
 * the function match() is called which returns the line with the next match.
 * If this line is the NIL_LINE, it means that a match could not be found.
 * Find_x() and find_y() display the right page on the screen, and return
 * the right coordinates for x and y. These coordinates are passed to move_to()
 */
void search(message, method)
char *message;
FLAG method;
{
  register REGEX *program;
  register LINE *match_line;

/* Get the expression */
  if ((program = get_expression(message)) == NIL_REG)
  	return;

  set_cursor(0, ymax);
  flush();
/* Find the match */
  if ((match_line = match(program, cur_text, method)) == NIL_LINE) {
  	if (quit == TRUE)
  		status_line("Aborted", NIL_PTR);
  	else
  		status_line("Pattern not found.", NIL_PTR);
  	return;
  }

  move(0, program->start_ptr, find_y(match_line));
  clear_status();
}

/*
 * find_y() checks if the matched line is on the current page.  If it is, it
 * returns the new y coordinate, else it displays the correct page with the
 * matched line in the middle and returns the new y value;
 */
int find_y(match_line)
LINE *match_line;
{
  register LINE *line;
  register int count = 0;

/* Check if match_line is on the same page as currently displayed. */
  for (line = top_line; line != match_line && line != bot_line->next;
  						      line = line->next)
  	count++;
  if (line != bot_line->next)
  	return count;

/* Display new page, with match_line in center. */
  if ((line = proceed(match_line, -(screenmax >> 1))) == header) {
  /* Can't display in the middle. Make first line of file top_line */
  	count = 0;
  	for (line = header->next; line != match_line; line = line->next)
  		count++;
  	line = header->next;
  }
  else	/* New page is displayed. Set cursor to middle of page */
  	count = screenmax >> 1;

/* Reset pointers and redraw the screen */
  reset(line, 0);
  RD();

  return count;
}

/* Opcodes for characters */
#define	NORMAL		0x0200
#define DOT		0x0400
#define EOLN		0x0800
#define STAR		0x1000
#define BRACKET		0x2000
#define NEGATE		0x0100
#define DONE		0x4000

/* Mask for opcodes and characters */
#define LOW_BYTE	0x00FF
#define HIGH_BYTE	0xFF00

/* Previous is the contents of the previous address (ptr) points to */
#define previous(ptr)		(*((ptr) - 1))

/* Buffer to store outcome of compilation */
int exp_buffer[BLOCK_SIZE];

/* Errors often used */
char *too_long = "Regular expression too long";

/*
 * Reg_error() is called by compile() is something went wrong. It set the
 * status of the structure to error, and assigns the error field of the union.
 */
#define reg_error(str)	program->status = REG_ERROR, \
  					program->result.err_mess = (str)
/*
 * Finished() is called when everything went right during compilation. It
 * allocates space for the expression, and copies the expression buffer into
 * this field.
 */
void finished(program, last_exp)
register REGEX *program;
int *last_exp;
{
  register int length = (last_exp - exp_buffer) * sizeof(int);

/* Allocate space */
  program->result.expression = (int *) alloc(length);
/* Copy expression. (expression consists of ints!) */
  bcopy(exp_buffer, program->result.expression, length);
}

/*
 * Compile compiles the pattern into a more comprehensible form and returns a 
 * REGEX structure. If something went wrong, the status field of the structure
 * is set to REG_ERROR and an error message is set into the err_mess field of
 * the union. If all went well the expression is saved and the expression
 * pointer is set to the saved (and compiled) expression.
 */
void compile(pattern, program)
register char *pattern;			/* Pointer to pattern */
REGEX *program;
{
  register int *expression = exp_buffer;
  int *prev_char;			/* Pointer to previous compiled atom */
  int *acct_field;		/* Pointer to last BRACKET start */
  FLAG negate;			/* Negate flag for BRACKET */
  char low_char;			/* Index for chars in BRACKET */
  char c;

/* Check for begin of line */
  if (*pattern == '^') {
  	program->status = BEGIN_LINE;
  	pattern++;
  }
  else {
  	program->status = 0;
/* If the first character is a '*' we have to assign it here. */
  	if (*pattern == '*') {
  		*expression++ = '*' + NORMAL;
  		pattern++;
  	}
  }

  for (; ;) {
  	switch (c = *pattern++) {
  	case '.' :
  		*expression++ = DOT;
  		break;
  	case '$' :
  		/*
  		 * Only means EOLN if it is the last char of the pattern
  		 */
  		if (*pattern == '\0') {
  			*expression++ = EOLN | DONE;
  			program->status |= END_LINE;
  			finished(program, expression);
  			return;
  		}
  		else
  			*expression++ = NORMAL + '$';
  		break;
  	case '\0' :
  		*expression++ = DONE;
  		finished(program, expression);
  		return;
  	case '\\' :
  		/* If last char, it must! mean a normal '\' */
  		if (*pattern == '\0')
  			*expression++ = NORMAL + '\\';
  		else
  			*expression++ = NORMAL + *pattern++;
  		break;
  	case '*' :
  		/*
  		 * If the previous expression was a [] find out the
  		 * begin of the list, and adjust the opcode.
  		 */
  		prev_char = expression - 1;
  		if (*prev_char & BRACKET)
  			*(expression - (*acct_field & LOW_BYTE))|= STAR;
  		else
  			*prev_char |= STAR;
  		break;
  	case '[' :
  		/*
  		 * First field in expression gives information about
  		 * the list.
  		 * The opcode consists of BRACKET and if necessary
  		 * NEGATE to indicate that the list should be negated
  		 * and/or STAR to indicate a number of sequence of this 
  		 * list.
  		 * The lower byte contains the length of the list.
  		 */
  		acct_field = expression++;
  		if (*pattern == '^') {	/* List must be negated */
  			pattern++;
  			negate = TRUE;
  		}
  		else
  			negate = FALSE;
  		while (*pattern != ']') {
  			if (*pattern == '\0') {
  				reg_error("Missing ]");
  				return;
  			}
  			if (*pattern == '\\')
  				pattern++;
  			*expression++ = *pattern++;
  			if (*pattern == '-') {
  						/* Make list of chars */
  				low_char = previous(pattern);
  				pattern++;	/* Skip '-' */
  				if (low_char++ > *pattern) {
  					reg_error("Bad range in [a-z]");
  					return;
  				}
  				/* Build list */
  				while (low_char <= *pattern)
  					*expression++ = low_char++;
  				pattern++;
  			}
  			if (expression >= &exp_buffer[BLOCK_SIZE]) {
  				reg_error(too_long);
  				return;
  			}
  		}
  		pattern++;			/* Skip ']' */
  		/* Assign length of list in acct field */
  		if ((*acct_field = (expression - acct_field)) == 1) {
  			reg_error("Empty []");
  			return;
  		}
  		/* Assign negate and bracket field */
  		*acct_field |= BRACKET;
  		if (negate == TRUE)
  			*acct_field |= NEGATE;
  		/*
  		 * Add BRACKET to opcode of last char in field because
  		 * a '*' may be following the list.
  		 */
  		previous(expression) |= BRACKET;
  		break;
  	default :
  		*expression++ = c + NORMAL;
  	}
  	if (expression == &exp_buffer[BLOCK_SIZE]) {
  		reg_error(too_long);
  		return;
  	}
  }
  /* NOTREACHED */
}

/*
 * Match gets as argument the program, pointer to place in current line to 
 * start from and the method to search for (either FORWARD or REVERSE).
 * Match() will look through the whole file until a match is found.
 * NIL_LINE is returned if no match could be found.
 */
LINE *match(program, string, method)
REGEX *program;
char *string;
register FLAG method;
{
  register LINE *line = cur_line;
  char old_char;				/* For saving chars */

/* Corrupted program */
  if (program->status == REG_ERROR)
  	return NIL_LINE;

/* Check part of text first */
  if (!(program->status & BEGIN_LINE)) {
  	if (method == FORWARD) {
  		if (line_check(program, string + 1, method) == MATCH)
  			return cur_line;	/* Match found */
  	}
  	else if (!(program->status & END_LINE)) {
  		old_char = *string;	/* Save char and */
  		*string = '\n';		/* Assign '\n' for line_check */
  		if (line_check(program, line->text, method) == MATCH) {
  			*string = old_char; /* Restore char */
  			return cur_line;    /* Found match */
  		}
  		*string = old_char;	/* No match, but restore char */
  	}
  }

/* No match in last (or first) part of line. Check out rest of file */
  do {
  	line = (method == FORWARD) ? line->next : line->prev;
  	if (line->text == NIL_PTR)	/* Header/tail */
  		continue;
  	if (line_check(program, line->text, method) == MATCH)
  		return line;
  } while (line != cur_line && quit == FALSE);

/* No match found. */
  return NIL_LINE;
}

/*
 * Line_check() checks the line (or rather string) for a match. Method
 * indicates FORWARD or REVERSE search. It scans through the whole string
 * until a match is found, or the end of the string is reached.
 */
int line_check(program, string, method)
register REGEX *program;
char *string;
FLAG method;
{
  register char *textp = string;

/* Assign start_ptr field. We might find a match right away! */
  program->start_ptr = textp;

/* If the match must be anchored, just check the string. */
  if (program->status & BEGIN_LINE)
  	return check_string(program, string, NIL_INT);
  
  if (method == REVERSE) {
  	/* First move to the end of the string */
  	for (textp = string; *textp != '\n'; textp++)
  		;
  	/* Start checking string until the begin of the string is met */
  	while (textp >= string) {
  		program->start_ptr = textp;
  		if (check_string(program, textp--, NIL_INT))
  			return MATCH;
  	}
  }
  else {
  	/* Move through the string until the end of is found */
	while (quit == FALSE && *textp != '\0') {
  		program->start_ptr = textp;
  		if (check_string(program, textp, NIL_INT))
  			return MATCH;
		if (*textp == '\n')
			break;
		textp++;
  	}
  }

  return NO_MATCH;
}

/*
 * Check() checks of a match can be found in the given string. Whenever a STAR
 * is found during matching, then the begin position of the string is marked
 * and the maximum number of matches is performed. Then the function star()
 * is called which starts to finish the match from this position of the string
 * (and expression). Check() return MATCH for a match, NO_MATCH is the string 
 * couldn't be matched or REG_ERROR for an illegal opcode in expression.
 */
int check_string(program, string, expression)
REGEX *program;
register char *string;
int *expression;
{
  register int opcode;		/* Holds opcode of next expr. atom */
  char c;				/* Char that must be matched */
  char *mark;			/* For marking position */
  int star_fl;			/* A star has been born */

  if (expression == NIL_INT)
  	expression = program->result.expression;

/* Loop until end of string or end of expression */
  while (quit == FALSE && !(*expression & DONE) &&
					   *string != '\0' && *string != '\n') {
  	c = *expression & LOW_BYTE;	  /* Extract match char */
  	opcode = *expression & HIGH_BYTE; /* Extract opcode */
  	if (star_fl = (opcode & STAR)) {  /* Check star occurrence */
  		opcode &= ~STAR;	  /* Strip opcode */
  		mark = string;		  /* Mark current position */
  	}
  	expression++;		/* Increment expr. */
  	switch (opcode) {
  	case NORMAL :
  		if (star_fl)
  			while (*string++ == c)	/* Skip all matches */
  				;
  		else if (*string++ != c)
  			return NO_MATCH;
  		break;
  	case DOT :
  		string++;
  		if (star_fl)			/* Skip to eoln */
  			while (*string != '\0' && *string++ != '\n')
  				;
  		break;
  	case NEGATE | BRACKET:
  	case BRACKET :
  		if (star_fl)
  			while (in_list(expression, *string++, c, opcode)
								       == MATCH)
  				;
  		else if (in_list(expression, *string++, c, opcode) == NO_MATCH)
  			return NO_MATCH;
  		expression += c - 1;	/* Add length of list */
  		break;
  	default :
  		panic("Corrupted program in check_string()");
  	}
  	if (star_fl) 
  		return star(program, mark, string, expression);
  }
  if (*expression & DONE) {
  	program->end_ptr = string;	/* Match ends here */
  	/*
  	 * We might have found a match. The last thing to do is check
  	 * whether a '$' was given at the end of the expression, or
  	 * the match was found on a null string. (E.g. [a-z]* always
  	 * matches) unless a ^ or $ was included in the pattern.
  	 */
  	if ((*expression & EOLN) && *string != '\n' && *string != '\0')
  		return NO_MATCH;
	if (string == program->start_ptr && !(program->status & BEGIN_LINE)
					 && !(*expression & EOLN))
  		return NO_MATCH;
  	return MATCH;
  }
  return NO_MATCH;
}

/*
 * Star() calls check_string() to find out the longest match possible.
 * It searches backwards until the (in check_string()) marked position
 * is reached, or a match is found.
 */
int star(program, end_position, string, expression)
REGEX *program;
register char *end_position;
register char *string;
int *expression;
{
  do {
  	string--;
  	if (check_string(program, string, expression))
  		return MATCH;
  } while (string != end_position);

  return NO_MATCH;
}

/*
 * In_list() checks if the given character is in the list of []. If it is
 * it returns MATCH. if it isn't it returns NO_MATCH. These returns values
 * are reversed when the NEGATE field in the opcode is present.
 */
int in_list(list, c, list_length, opcode)
register int *list;
char c;
register int list_length;
int opcode;
{
  if (c == '\0' || c == '\n')	/* End of string, never matches */
  	return NO_MATCH;
  while (list_length-- > 1) {	/* > 1, don't check acct_field */
  	if ((*list & LOW_BYTE) == c)
  		return (opcode & NEGATE) ? NO_MATCH : MATCH;
  	list++;
  }
  return (opcode & NEGATE) ? MATCH : NO_MATCH;
}

/*
 * Dummy_line() adds an empty line at the end of the file. This is sometimes
 * useful in combination with the EF and DN command in combination with the
 * Yank command set.
 */
void dummy_line()
{
	(void) line_insert(tail->prev, "\n", 1);
	tail->prev->shift_count = DUMMY;
	if (last_y != screenmax) {
		last_y++;
		bot_line = bot_line->next;
	}
}