1 extern queue	squeue;			// the three queues on which ranges reside
2 extern queue	bfqueue;
3 extern queue	ufqueue;
4 
5 extern double minfull;
6 
7 extern double coltol;
8 
9 int anymore();
10 
11 // The following is used in some calls to range::enqueue(int = 0).
12 #define ANDBLOCK 1
13 
14 class page;
15 
16 enum { DRAFT = 0, FINAL = 1 };
17 
18 // The mergestream currpage->stage serves as a staging area for page makeup:
19 // when primed, it contains a minimal acceptable chunk of input ranges.
20 // The page must either take or leave everything that's on stage.
21 class mergestream : public queue {
22 	page	*currpage;		// current page that's accepting stuff
23   public:
24 	mergestream(page *cp)	{ currpage = cp; unblock(); }
25 	void	unblock();
26 	int	prime();		// stage next legal chunk
27 	void	pend();			// process pending chunk on stage
28 };
29 
30 // The multicol currpage->twocol is the two-column piece of the page to which
31 // two-column ranges are currently being added.
32 // The page sets htavail to indicate how tall it is allowed to become.
33 // All ranges on definite must be placed when the multicol is printed.
34 // Each of these definite ranges also resides on one of column[0] and [1],
35 // which represent the current best guess about how to divide definite
36 // between the two columns.
37 class multicol : public range {
38 	page	*currpage;		// current page that's accepting stuff
39 	stream	definite;		// definitely on page
40 	stream	scratch;		// for trial compositions
41 	stream	column[2];		// left (0) and right (1) columns
42 	int	leftblocked;		// OK to add to left column?
43 	int	htavail;		// max possible ht, set by page::tryout()
44 	int	prevhtavail;		// max 2-colht last time we added something
45 	friend	class page;
46 public:
47 	multicol(page *cp)	{ currpage = cp;
48 				leftblocked = 0;
49 				htavail = 0;
50 				prevhtavail = -1;
51 				setgoal(NOGOAL); }
52 					// the two-column piece behaves as part
53 					// of the stream of single-column input.
54 	int	numcol()	{ return 1; }
55 	int	nonempty()	{ return definite.more(); }
56 	void	choosecol(range *, int);// add first arg to one or other column
57 	void	choosecol(stream*, int);// add *all ranges on first arg*
58 					// to one or other column
59 					// NOT the same as a mapcar of the
60 					// preceding function over the ranges
61 					// on the first argument!
62 	void	compose(int);		// divide into two columns
63 	void	tryout();		// decide which column gets stage contents
64 	void	stretch(int);		// justify both columns to given height
65 	int	print(int curv, int col);
66 	int	height();		// an upper bound on actual height
67 	int	rawht()		{ return max(column[0].rawht(), column[1].rawht()); }
68 	void	reheight(int *cv, int *mv)
69 				{ *cv += height(); *mv = max(*mv, *cv); }
70 	void	dump();
71 	int	isvbox()	{ return nonempty(); }	// during trimspace()
72 };
73 
74 // These sentinel ranges are used to separate the ranges on twocol::definite
75 // into the chunks in which they came from the staging area.
76 // Thus, they preserve the results of the computation that was done to prime
77 // page::stage.
78 class sentrange : public range {
79   public:
80 	sentrange()		{ }
81 	int	numcol()	{ return 2; }
82 	int	issentinel()	{ return 1; }
83 };
84 
85 class page {
86 	int	pagesize;		// allowed maximum height
87 	int	prevncol;		// was last item tried 1- or 2-column?
88 	int	vsince;			// how many vboxes from "current" BS
89 					// (to avoid putting a single line on
90 					// a page with a very large floatable)
91 	stream	definite;		// definitely on page, in input order
92 	stream	scratch;		// playground in which to alter page
93 	void	cmdproc();		// process any of several commands
94 	void	parmproc();		// process any of several parameters
95 	void	tryout();		// see whether current stage contents fit
96 	void	compose(int);		// float and trim current page contents
97 	void	makescratch(int);	// fill scratch area
98 	void	commit();		// accept the items on stage
99 	void	welsh();		// reject the items on stage
100 	void	adddef(range *r);	// add to one of the definite queues
101 					// (definite or twocol->definite)
102   public:
103 	mergestream *stage;
104 	friend	class mergestream;
105 	multicol *twocol;
106 	friend class multicol;
107 	page(int p)	{ pagesize = p;
108 			prevncol = 1;
109 			vsince = 0;
110 			stage = new mergestream(this);
111 			twocol = new multicol(this); }
112 	~page()	{ definite.freeall(); scratch.freeall(); }
113 	void	fill();
114 	int	blank()	{ return !definite.more() && !twocol->definite.more();}
115 	void	print();
116 };
117 
118 // functions in page.c
119 int main(int, char **);