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/* M. Beeson for Windows Mathpert */
/* located terms, and prototypes and specifications
   of functions for managing them */
/*
1.28.95 Original date
1.30.95 last modified
5.8.13 made cons an exported function
*/

/*_________________________________________________________________*/
typedef struct il
   { int data;  /* can be negative, but must have enough room to
                    store an arbitrary arity; this would only cause
                    trouble on arities over 32K */
     unsigned short functor;
     struct il *next;
   } pathlist;

pathlist * cons(int x, unsigned short y, pathlist *tail);
/* stick one item on the front of a list */
pathlist * copy_pathlist(pathlist *);
/*__________________________________________________________________*/
/* Linked lists of rectangles: */
/* We don't use the Windows RECT structure because we want the
components to be longs, even under Win16.  When a large term is
displayed, it is first computed how to display it without
line-breaking, on an infinitely wide screen; and for this longs
are needed, as otherwise we get overflow e.g. on (2x+3)^99
   The structure BIGRECT is defined in bigrect.h
*/


typedef struct rl { BIGRECT rect;
                    struct rl *next;
                    struct rl *prev;
                    int wl;     /* y-coord of the line's water level, in pixel coords */
                  } rectlist;   /* doubly linked list of rectangles with waterlevels */

/* The following typedef for 'located term' will be used for
terms whose location on the screen is tracked for hit-testing,
to support selection of a formula from the screen.
*/

typedef union largtag larg;
/*  using larg * below instead of void * makes it possible to
inspect lterms in the Borland debugger.
*/

typedef struct lt
   { BIGRECT r;  /* screen rectangle in window pixel coordinates */
                 /* coordinates can be negative or off-screen    */
                 /* This is the smallest rectangle enclosing the
                    WHOLE term, even for broken terms            */
     unsigned short symbol;
     unsigned short arity;
     unsigned short info;
     block block;      /* original papyrus-coordinate height, width, water level, and bra */
     larg *args;   /* pointer to array of children (lterms except in atomic case) */
     pathlist *path;  /* path to this term from some term of which it is a subterm.
                        Just which term depends on the use at hand */
     rectlist *linelist;   /* in the case of a broken term, points to
                       a linked list of rectangles for the different lines,
                       including the first line. Must be NULL for an
                       unbroken term. */
   } lterm;

union largtag
   { lterm t;
     long i;
     double d;
     bignum b;
   };

/* Macros for accessing the parts of an lterm: */

#define LARG(N,F)    (((lterm *)(F).args)[N])
#define LARGPTR(t)   ((lterm *) ((t).args))
#define LINES(F)     ((BIGRECT *)(LARGPTR(F) + F.arity))
#define LARGREP(t,n,newarg)   ((lterm *) ((t).args))[n] = newarg

/*_________________________________________________________________*/
/* linked lists of lterms:  */
typedef struct ll { lterm data;
                    struct ll *next;
                  } ltermlist;


/* stick one item on the head of a list */

/*_________________________________________________________________*/
void locate_term(term bt, BIGRECT *r, lterm *ans);
/* convert a bblocked term bt into a located term that
fits in rectangle r, if possible. Break lines to
the width of r (except matrices) and if the result is
too long, the rectangles in *ans will not all be
contained in r; too bad. */

/*_________________________________________________________________*/
int lbreak(lterm *t);
/*  Redefine the rectangles in t so it fits on the papyrus */
/*_________________________________________________________________*/
void set_paper(BIGRECT *r);
/* tell lbreak what the window rectangle is, so it knows where
to start a new line when a line must be broken */
void get_paper(BIGRECT *r);
/* retrieve a copy of the rectangle set in set_paper */
term extract_bterm(lterm t);
/* extract a bblocked term from an lterm */
void wdisplay_lterm(unsigned long hdc, lterm, unsigned long);
/* display an lterm on the given hdc, writing each
subterm in its own rectangle.  Use a static global
in the file for the hdc and don't pass it to each
recursive call.  Use the specified color.  */
void ldisplay(lterm);
/* using the colors set up by wdisplay_lterm */
void shift(lterm *, long, long);
/* Move the rectangles by the specified amounts in x and y directions */
int paren_displacement(lterm t);
void lastrow(lterm, BIGRECT *, int*);
/* in bdisplay.c, but also used in printdlg.c */
term abstract(lterm);
/* discard display info to produce an ordinary term */
int lcontainseq(lterm);
int linterval_as_and(lterm);
int lequals(lterm,lterm);
void strip_parens(lterm *);
void move_lterm_up(lterm *, int);
lterm located_subrange(lterm t, int j, int m);