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#ifndef lint
static char *RCSid = "$Id: stack.c,v 1.13 1993/05/10 06:06:43 anders Exp anders $";
#endif
/*
* The Regina Rexx Interpreter
* Copyright (C) 1992-1994 Anders Christensen <anders@pvv.unit.no>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/* Consept of implementation:
* In this description, the stack is described as growing upwards
* The stack has two pointers to the ends of a double-linked list,
* which contains entries consisting of just a pointer to the text (in
* a struct streng) in addition to pointers to next and previous
* entry. Last box' next, and first box' prev is both NIL. The text
* pointer points to the text of that line in the stack.
* If the text pointer is NIL, then that box in the stack-structure is
* just symbolizing a stack buffer mark. The integer variable
* 'buffers' contains the current number of buffermarks in the stack.
* A buffer is the lines between two buffermarks. The first buffer mark
* (for buffer 0) is not marked, but is implicit the bottom of the
* stack. The last buffer is the lines between the uppermost
* buffermark and the top of the stack.
* Initialy all lines are put in buffer 0. When a new buffer is
* created, lines pushed lifo is put on top of that buffer, and lines
* queued fifo are put in the bottom of that buffer (i.e. not in the
* bottom of buffer 0.) Lines pushed on the stack are 'eaten' and
* there must not be any referances to them in other parts of the
* program after they have been pushed.
* When reading lines from the stack, and all lines in the current
* buffer has been read, the buffer-mark will be removed, and lines
* are read from the buffer underneath. Lines read from the stack must
* be free'ed by the routine that popped them from the stack.
* When the whole stack is empty, lines are read from standard input.
* Buffer 0 is contains the lines between the bottom of the stack, and
* the first buffermark on the stack, the first buffer, is the lines
* between buffermark 1 and buffer mark 2.
* When creating a buffer, the value returned will be the number of
* buffermarks in the stack after the new buffermark is created.
* When destroying buffers, the parameter given will equal the number
* of the lowest buffermark to be destroyed (i.e dropbuf 4) will leave
* 3 buffermarks on the stack).
* Possible extentions:
* o A new 'hard-buffer', that is not removed when a line is popped
* from it while it is empty
*/
#include "rexx.h"
#include <stdio.h>
#include <assert.h>
#include <ctype.h>
/*
* Hide the definition of the stack from the rest of the program
*/
typedef struct stacklinestruct *stacklineptr ;
typedef struct stacklinestruct
{
stacklineptr next, prev ;
streng *contents ;
} stackline ;
/*
* Pointers to first and last line in the stack.
*/
static stacklineptr lastline=NULL ;
static stacklineptr firstline=NULL ;
/*
* The number of buffermarks in the stack
*/
static int buffers=0 ;
/*
* Pointers to first and last entry in the temporary stack
*/
static stacklineptr firstbox=NULL, lastbox=NULL ;
/*
* This routines accumulates stackentries, but without pushing them
* on the actual stack, used when stacking the output of an external
* command. If such a command also reads from the stack, the output
* can not be flushed to the stack before the command has finished
* reading (else, the command might read its own output.)
*
* Parameter is the streng to stack.
*/
void tmp_stack( streng *value, int is_fifo )
{
stacklineptr ptr=NULL ;
assert( ((lastbox)&&(firstbox)) || ((!lastbox)&&(!firstbox)) ) ;
assert( (value) && (Str_max(value) >= Str_len(value)) ) ;
#if OLD_OPTIONS
if (currlevel->u.options.flushstack)
#else
if ( get_options_flag( currlevel, EXT_FLUSHSTACK ) )
#endif
{
if (is_fifo)
stack_fifo( value ) ;
else
stack_lifo( value ) ;
}
else
{
ptr = Malloc( sizeof(struct stacklinestruct) ) ;
ptr->contents = value ;
ptr->next = NULL ;
ptr->prev = lastbox ;
if (firstbox)
lastbox->next = ptr ;
else
firstbox = ptr ;
lastbox = ptr ;
}
}
/*
* Flushes the content of the temporary stack created by (possibly
* multiple) calls to tmp_stack().
*
* If parameter is true, lines are stacked fifo, which requires their
* order to be reversed first.
*/
void flush_stack( int is_fifo )
{
stacklineptr ptr=NULL, tptr=NULL ;
if (firstbox==NULL)
{
/* nothing in temporary stack to flush */
assert(lastbox==NULL) ;
return ;
}
/* stack it either fifo or lifo */
if (is_fifo)
{
/* if fifo, temporary stack must be reversed first */
/* travelling in 'prev' direction, since stack is reversed */
for (ptr=firstbox; ptr; ptr=ptr->prev )
{
tptr = ptr->prev ;
ptr->prev = ptr->next ;
ptr->next = tptr ;
}
/* temporary stack now in right order, link to top of real stack */
firstbox->next = firstline ;
if (firstline)
firstline->prev = firstbox ;
else
lastline = firstbox ;
firstline = lastbox ;
}
else
{
/* everything is in right order, just link them together */
firstbox->prev = lastline ;
if (lastline)
lastline->next = firstbox ;
else
firstline = firstbox ;
lastline = lastbox ;
}
/* reset the pointers, to signify that temporary stack is empty */
lastbox = firstbox = NULL ;
}
/*
* Pushes 'line' onto the REXX stack, lifo, and sets 'lastline' to
* point to the new line. The line is put on top of the current
* buffer.
*/
void stack_lifo( streng *line )
{
stacklineptr newbox=NULL ;
newbox = (stacklineptr)Malloc(sizeof(stackline)) ;
if (lastline)
{
lastline->next = newbox ;
newbox->prev = lastline ;
}
else
{
newbox->prev = NULL ;
firstline = newbox ;
}
if (!line)
buffers++ ;
newbox->next = NULL ;
newbox->contents = line ;
lastline = newbox ;
}
/*
* Puts 'line' on the REXX stack, fifo. This routine is similar to
* stack_lifo but the differences are big enough to have a separate
* routine. The line is put in the bottom of the current buffer,
* that is just above the uppermost buffer mark, or at the bottom
* of the stack, if there are no buffer marks.
*/
void stack_fifo( streng *line )
{
stacklineptr newbox=NULL, ptr=NULL ;
if (!line)
buffers++ ;
/* Bug: inserts into bottom of stack, not bottom of current buffer */
newbox = (stacklineptr)Malloc(sizeof(stackline)) ;
newbox->prev = newbox->next = NULL ;
newbox->contents = line ;
for (ptr=lastline;(ptr)&&(ptr->contents);ptr=ptr->prev) ;
if (ptr)
{
newbox->prev = ptr ;
newbox->next = ptr->next ;
if (ptr->next)
ptr->next->prev = newbox ;
else
lastline = newbox ;
ptr->next = newbox ;
}
else
{
newbox->next = firstline ;
firstline = newbox ;
if (newbox->next)
newbox->next->prev = newbox ;
if (!lastline)
lastline = newbox ;
}
}
/*
* Removes one (or several) buffers from the stack. The number of
* buffers to remove is decided by 'number', which is the number of
* buffers to remain on the stack. The global variable buffer
* contains the number of buffermarks currently in the stack.
*
* When number==2, buffer 0 (the implisit), and buffer 1 (the first
* buffer created by the user) are the only that remain. All lines
* from buffermark 2 (inclusive) and above are removed. Remember
* that buffer N is the lines following the N'th buffermark, until
* end-of-stack or another buffermark is reached.
*
* If number is less than zero, then abs(number) buffers is removed
* from the top of the stack (or until the stack is empty).
* If the number is zero, the stack is emptied. If a buffer with a
* number that is higher than the current buffer is spesified,
* errorcode is retured.
*/
int drop_buffer( int number )
{
stacklineptr ptr=NULL, nptr=NULL ;
if (number<0)
number = (buffers + number + 1) ;
assert(buffers>=0) ;
for (ptr=lastline; (ptr) && (number<=buffers); ptr=nptr)
{
nptr = ptr->prev ;
if (ptr->contents)
Free_string(ptr->contents) ;
else
buffers-- ;
Free(ptr) ;
if (nptr)
nptr->next = NULL ;
}
if (!(lastline=ptr))
firstline = NULL ;
if (buffers<0)
buffers = 0 ;
return buffers ;
}
/*
* Fetches a line from the top of the stack. If the current buffer
* does not contain any lines, it is removed and the second current
* buffer is search for a line etc. If there isn't any lines in the
* stack, a line is read from the standard input.
*/
streng *popline( void )
{
extern sysinfo systeminfo ;
streng *contents=NULL ;
stacklineptr line=NULL ;
if ((line=lastline))
{
contents = line->contents ;
lastline = line->prev ;
if (!line->prev)
firstline = NULL ;
else
line->prev->next = NULL ;
Free(line) ;
if (!contents)
{
buffers-- ;
contents = popline() ;
}
}
else
{
int rc = HOOK_GO_ON ;
if (systeminfo->hooks & HOOK_MASK(HOOK_PULL))
rc = hookup( HOOK_PULL, &contents ) ;
if (rc==HOOK_GO_ON)
contents = readkbdline() ;
assert( contents ) ;
}
return contents ;
}
/*
* Counts the lines in the stack.
*/
int lines_in_stack( void )
{
stacklineptr ptr=NULL ;
int lines=0 ;
ptr = firstline ;
for (lines=0;ptr;ptr=ptr->next)
if (ptr->contents)
lines++ ;
return lines ;
}
/*
* Returns boolean expression: is the stack empty?
*/
int stack_empty( void )
{
stacklineptr ptr=NULL ;
for (ptr=firstline;ptr;ptr=ptr->next)
if (ptr->contents)
return 0 ;
return 1 ;
}
#ifdef TRACEMEM
/*
* Marks all chunks of dynamic allocated memory that are allocated
* to the stack subsystem.
*/
void mark_stack( void )
{
stacklineptr ptr=NULL ;
for (ptr=firstline;ptr;ptr=ptr->next)
{
markmemory(ptr,TRC_STACKBOX) ;
if (ptr->contents)
markmemory(ptr->contents,TRC_STACKLINE) ;
}
}
#endif
/*
* Creates a new buffer, by putting a buffer mark at the top of the
* stack. (This could be implemented as {push_line(NULL)} and a
* special test for (line==NULL) in push_line())
*/
int make_buffer( void )
{
stack_lifo( NULL ) ;
return buffers ;
}
/*
* Dumps the contents of the stack to standard error. Buffer marks are
* indicated in the printout.
*/
void type_buffer( void )
{
stacklineptr ptr=NULL ;
char *cptr=NULL, *stop=NULL ;
int counter=0 ;
fprintf(stddump,"==> Lines: %d\n", lines_in_stack()) ;
fprintf(stddump,"==> Buffer: %d\n", counter=buffers) ;
for (ptr=lastline; ptr; ptr=ptr->prev)
{
if (ptr->contents)
{
putc( '"', stddump ) ;
stop = Str_end(ptr->contents) ;
for (cptr=ptr->contents->value; cptr<stop; cptr++)
putc( (isprint(*cptr) ? (*cptr) : '?'), stddump ) ;
putc( '"', stddump ) ;
putc( 0x0a, stddump ) ;
}
else
fprintf(stddump,"==> Buffer: %d\n",--counter) ; }
fprintf(stddump,"==> End of Stack\n") ;
fflush(stddump) ;
}
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