[project @ 2002-04-24 16:31:37 by simonmar]
[packages/base.git] / Text / Html / BlockTable.hs
1 -----------------------------------------------------------------------------
2 -- |
3 -- Module : Text.Html.BlockTable
4 -- Copyright : (c) Andy Gill, and the Oregon Graduate Institute of
5 -- Science and Technology, 1999-2001
6 -- License : BSD-style (see the file libraries/core/LICENSE)
7 --
8 -- Maintainer : Andy Gill <andy@galconn.com>
9 -- Stability : experimental
10 -- Portability : portable
11 --
12 -- $Id: BlockTable.hs,v 1.2 2002/04/24 16:31:46 simonmar Exp $
13 --
14 -- An Html combinator library
15 --
16 -----------------------------------------------------------------------------
17
18 module Text.Html.BlockTable (
19
20 -- Datatypes:
21
22 BlockTable, -- abstract
23
24 -- Contruction Functions:
25
26 single,
27 above,
28 beside,
29
30 -- Investigation Functions:
31
32 getMatrix,
33 showsTable,
34 showTable,
35
36 ) where
37
38 import Prelude
39
40 infixr 4 `beside`
41 infixr 3 `above`
42
43 -- These combinators can be used to build formated 2D tables.
44 -- The specific target useage is for HTML table generation.
45
46 {-
47 Examples of use:
48
49 > table1 :: BlockTable String
50 > table1 = single "Hello" +-----+
51 |Hello|
52 This is a 1x1 cell +-----+
53 Note: single has type
54
55 single :: a -> BlockTable a
56
57 So the cells can contain anything.
58
59 > table2 :: BlockTable String
60 > table2 = single "World" +-----+
61 |World|
62 +-----+
63
64
65 > table3 :: BlockTable String
66 > table3 = table1 %-% table2 +-----%-----+
67 |Hello%World|
68 % is used to indicate +-----%-----+
69 the join edge between
70 the two Tables.
71
72 > table4 :: BlockTable String
73 > table4 = table3 %/% table2 +-----+-----+
74 |Hello|World|
75 Notice the padding on the %%%%%%%%%%%%%
76 smaller (bottom) cell to |World |
77 force the table to be a +-----------+
78 rectangle.
79
80 > table5 :: BlockTable String
81 > table5 = table1 %-% table4 +-----%-----+-----+
82 |Hello%Hello|World|
83 Notice the padding on the | %-----+-----+
84 leftmost cell, again to | %World |
85 force the table to be a +-----%-----------+
86 rectangle.
87
88 Now the table can be rendered with processTable, for example:
89 Main> processTable table5
90 [[("Hello",(1,2)),
91 ("Hello",(1,1)),
92 ("World",(1,1))],
93 [("World",(2,1))]] :: [[([Char],(Int,Int))]]
94 Main>
95 -}
96
97 -- ---------------------------------------------------------------------------
98 -- Contruction Functions
99
100 -- Perhaps one day I'll write the Show instance
101 -- to show boxes aka the above ascii renditions.
102
103 instance (Show a) => Show (BlockTable a) where
104 showsPrec p = showsTable
105
106 type TableI a = [[(a,(Int,Int))]] -> [[(a,(Int,Int))]]
107
108 data BlockTable a = Table (Int -> Int -> TableI a) Int Int
109
110
111 -- You can create a (1x1) table entry
112
113 single :: a -> BlockTable a
114 single a = Table (\ x y z -> [(a,(x+1,y+1))] : z) 1 1
115
116
117 -- You can compose tables, horizonally and vertically
118
119 above :: BlockTable a -> BlockTable a -> BlockTable a
120 beside :: BlockTable a -> BlockTable a -> BlockTable a
121
122 t1 `above` t2 = trans (combine (trans t1) (trans t2) (.))
123
124 t1 `beside` t2 = combine t1 t2 (\ lst1 lst2 r ->
125 let
126 -- Note this depends on the fact that
127 -- that the result has the same number
128 -- of lines as the y dimention; one list
129 -- per line. This is not true in general
130 -- but is always true for these combinators.
131 -- I should assert this!
132 -- I should even prove this.
133 beside (x:xs) (y:ys) = (x ++ y) : beside xs ys
134 beside (x:xs) [] = x : xs ++ r
135 beside [] (y:ys) = y : ys ++ r
136 beside [] [] = r
137 in
138 beside (lst1 []) (lst2 []))
139
140 -- trans flips (transposes) over the x and y axis of
141 -- the table. It is only used internally, and typically
142 -- in pairs, ie. (flip ... munge ... (un)flip).
143
144 trans :: BlockTable a -> BlockTable a
145 trans (Table f1 x1 y1) = Table (flip f1) y1 x1
146
147 combine :: BlockTable a
148 -> BlockTable b
149 -> (TableI a -> TableI b -> TableI c)
150 -> BlockTable c
151 combine (Table f1 x1 y1) (Table f2 x2 y2) comb = Table new_fn (x1+x2) max_y
152 where
153 max_y = max y1 y2
154 new_fn x y =
155 case compare y1 y2 of
156 EQ -> comb (f1 0 y) (f2 x y)
157 GT -> comb (f1 0 y) (f2 x (y + y1 - y2))
158 LT -> comb (f1 0 (y + y2 - y1)) (f2 x y)
159
160 -- ---------------------------------------------------------------------------
161 -- Investigation Functions
162
163 -- This is the other thing you can do with a Table;
164 -- turn it into a 2D list, tagged with the (x,y)
165 -- sizes of each cell in the table.
166
167 getMatrix :: BlockTable a -> [[(a,(Int,Int))]]
168 getMatrix (Table r _ _) = r 0 0 []
169
170 -- You can also look at a table
171
172 showsTable :: (Show a) => BlockTable a -> ShowS
173 showsTable table = shows (getMatrix table)
174
175 showTable :: (Show a) => BlockTable a -> String
176 showTable table = showsTable table ""