1/* Part of SWI-Prolog 2 3 Author: Jan Wielemaker 4 E-mail: J.Wielemaker@vu.nl 5 WWW: http://www.swi-prolog.org 6 Copyright (c) 2018-2020, CWI Amsterdam 7 All rights reserved. 8 9 Redistribution and use in source and binary forms, with or without 10 modification, are permitted provided that the following conditions 11 are met: 12 13 1. Redistributions of source code must retain the above copyright 14 notice, this list of conditions and the following disclaimer. 15 16 2. Redistributions in binary form must reproduce the above copyright 17 notice, this list of conditions and the following disclaimer in 18 the documentation and/or other materials provided with the 19 distribution. 20 21 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 29 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 31 ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 32 POSSIBILITY OF SUCH DAMAGE. 33*/ 34 35:- module(text_format, 36 [ format_paragraph/2, % +Text, +Options 37 trim_line/2 % +LineIn, -Line 38 ]). 39:- autoload(library(ansi_term),[ansi_format/3]). 40:- autoload(library(debug),[debug/3]). 41:- autoload(library(error),[must_be/2,type_error/2]). 42:- autoload(library(lists),[append/3,member/2,selectchk/3]). 43:- autoload(library(option),[select_option/3,option/2,option/3]).

Print formatted text to a terminal

This module is the core of the plain text rendering module, providing format_paragraph/2 which formats a plain text block, respecting left and right margins, text alignment, ANSI style elements, etc. */

75format_paragraph(Text, Options) :- 76 words(Text, Words), 77 format_lines(Words, 1, Options). 78 79format_lines([], _, _). 80format_lines(Words, LineNo, Options) :- 81 line_width(LineNo, Width, Options), 82 skip_spaces(Words, Words1), 83 take_words(Words1, 0, Width, Line0, HasBR, Words2), 84 skip_trailing_spaces(Line0, Line), 85 skip_spaces(Words2, Words3), 86 ( Words3 == [] 87 -> align_last_line(Options, OptionsLast), 88 format_line(Line, Width, LineNo, OptionsLast) 89 ; HasBR == true 90 -> align_last_line(Options, OptionsLast), 91 format_line(Line, Width, LineNo, OptionsLast), 92 LineNo1 is LineNo + 1, 93 format_lines(Words3, LineNo1, Options) 94 ; format_line(Line, Width, LineNo, Options), 95 LineNo1 is LineNo + 1, 96 format_lines(Words3, LineNo1, Options) 97 ). 98 99take_words([br(_)|T], _, _, [], true, T) :- 100 !. 101take_words([H|T0], X, W, [H|T], BR, Rest) :- 102 element_length(H, Len), 103 X1 is X+Len, 104 ( X1 =< W 105 -> true 106 ; X == 0 % take at least one word 107 ), 108 !, 109 take_words(T0, X1, W, T, BR, Rest). 110take_words(Rest, _, _, [], false, Rest).

116trim_line(Line0, Line) :- 117 skip_spaces(Line0, Line1), 118 skip_trailing_spaces(Line1, Line). 119 120skip_spaces([b(_,_)|T0], T) :- 121 !, 122 skip_spaces(T0, T). 123skip_spaces(L, L). 124 125skip_trailing_spaces(L, []) :- 126 skip_spaces(L, []), 127 !. 128skip_trailing_spaces([H|T0], [H|T]) :- 129 skip_trailing_spaces(T0, T). 130 131align_last_line(Options0, Options) :- 132 select_option(text_align(justify), Options0, Options1), 133 !, 134 Options = [text_align(left)|Options1]. 135align_last_line(Options, Options).

140format_line(Line, Width, LineNo, Options) :- 141 option(pad(Char), Options), 142 option(margin_right(MR), Options), 143 MR > 0, 144 !, 145 must_be(oneof([' ']), Char), % For now 146 format_line_(Line, Width, LineNo, Options), 147 forall(between(1, MR, _), put_char(' ')). 148format_line(Line, Width, LineNo, Options) :- 149 format_line_(Line, Width, LineNo, Options). 150 151format_line_(Line, Width, LineNo, Options) :- 152 float_right(Line, Line1, Right), 153 !, 154 trim_line(Line1, Line2), % TBD: Alignment with floats 155 trim_line(Right, Right2), 156 space_dim(Line2, _, WL), 157 space_dim(Right2, _, WR), 158 append(Line2, [b(0,Space)|Right2], Line3), 159 Space is Width - WL - WR, 160 emit_indent(LineNo, Options), 161 emit_line(Line3). 162format_line_(Line, Width, LineNo, Options) :- 163 option(text_align(justify), Options), 164 !, 165 justify(Line, Width), 166 emit_indent(LineNo, Options), 167 emit_line(Line). 168format_line_(Line, Width, LineNo, Options) :- 169 option(text_align(right), Options), 170 !, 171 flush_right(Line, Width, LineR), 172 emit_indent(LineNo, Options), 173 emit_line(LineR). 174format_line_(Line, Width, LineNo, Options) :- 175 option(text_align(center), Options), 176 option(pad(Pad), Options, _), 177 !, 178 center(Line, Width, Pad, LineR), 179 emit_indent(LineNo, Options), 180 emit_line(LineR). 181format_line_(Line, Width, LineNo, Options) :- 182 option(pad(_Char), Options), 183 !, 184 pad(Line, Width, Padded), 185 emit_indent(LineNo, Options), 186 emit_line(Padded). 187format_line_(Line, _Width, LineNo, Options) :- 188 emit_indent(LineNo, Options), 189 emit_line(Line). 190 191justify(Line, Width) :- 192 space_dim(Line, Spaces, W0), 193 Spread is Width - W0, 194 length(Spaces, SPC), 195 SPC > 0, 196 Spread > 0, 197 spread(Spread, SPC, Spaces), 198 !, 199 debug(format(justify), 'Justified ~d spaces over ~d gaps: ~p', 200 [Spread, SPC, Spaces]). 201justify(_, _). 202 203flush_right(Line, Width, [b(0,Spaces)|Line]) :- 204 space_dim(Line, _Spaces, W0), 205 Spaces is Width - W0. 206 207center(Line, Width, Pad, [b(0,Left)|Padded]) :- 208 space_dim(Line, _Spaces, W0), 209 Spaces is Width - W0, 210 Left is Spaces//2, 211 ( atom(Pad), 212 Right is Spaces - Left, 213 Right > 0 214 -> append(Line, [b(0,Right)], Padded) 215 ; Padded = Line 216 ). 217 218pad(Line, Width, Padded) :- 219 space_dim(Line, _Spaces, W0), 220 Spaces is Width - W0, 221 append(Line, [b(0,Spaces)], Padded).

228float_right(Line0, Line, Right) :- 229 member(w(_,_,Attrs), Line0), 230 memberchk(float(right), Attrs), 231 !, 232 do_float_right(Line0, Line, Right). 233 234do_float_right([], [], []). 235do_float_right([H0|T0], T, [H|R]) :- 236 float_right_word(H0, H), 237 !, 238 float_right_space(T0, T, R). 239do_float_right([H|T0], [H|T], R) :- 240 do_float_right(T0, T, R). 241 242float_right_word(w(W,L,A0), w(W,L,A)) :- 243 selectchk(float(right), A0, A). 244 245float_right_space([S|T0], T, [S|R]) :- 246 S = b(_,_), 247 !, 248 float_right_space(T0, T, R). 249float_right_space(Line, Line, []).

254space_dim(Line, Spaces, Width) :- 255 space_dim(Line, Spaces, 0, Width). 256 257space_dim([], [], Width, Width). 258space_dim([b(L,Var)|T0], [Var|T], W0, W) :- 259 !, 260 W1 is W0+L, 261 space_dim(T0, T, W1, W). 262space_dim([H|T0], T, W0, W) :- 263 word_length(H, L), 264 !, 265 W1 is W0+L, 266 space_dim(T0, T, W1, W).

273spread(Spread, SPC, Spaces) :- 274 spread_spc(SPC, Spread, Spaces). 275 276spread_spc(Cnt, Spread, [H|T]) :- 277 Cnt > 0, 278 !, 279 H is round(Spread/Cnt), 280 Cnt1 is Cnt - 1, 281 Spread1 is Spread-H, 282 spread_spc(Cnt1, Spread1, T). 283spread_spc(_, _, []).

288emit_line([]). 289emit_line([H|T]) :- 290 ( emit_line_element(H) 291 -> true 292 ; type_error(line_element, H) 293 ), 294 emit_line(T). 295 296emit_line_element(w(W,_, Attrs)) :- 297 ( Attrs = [] 298 -> write(W) 299 ; ansi_format(Attrs, '~w', [W]) 300 ). 301emit_line_element(b(Len, Extra)) :- 302 ( var(Extra) 303 -> Extra = 0 304 ; true 305 ), 306 Spaces is Len+Extra, 307 forall(between(1, Spaces, _), put_char(' ')). 308 309emit_indent(1, Options) :- 310 !, 311 option(margin_left(Indent), Options, 0), 312 option(hang(Hang), Options, 0), 313 ( option(bullet(BulletSpec), Options) 314 -> bullet_text(BulletSpec, Bullet), 315 atom_length(Bullet, BLen), 316 TheIndent is Indent+Hang-1-BLen, 317 emit_indent(TheIndent), 318 format('~w ', [Bullet]) 319 ; TheIndent is Indent+Hang, 320 emit_indent(TheIndent) 321 ). 322emit_indent(_, Options) :- 323 option(margin_left(Indent), Options, 0), 324 nl, 325 emit_indent(Indent). 326 327emit_indent(N) :- 328 forall(between(1, N, _), 329 put_char(' ')). 330 331line_width(1, Width, Options) :- 332 !, 333 option(width(Right), Options, 72), 334 option(margin_left(Indent), Options, 0), 335 option(margin_right(RightMargin), Options, 0), 336 option(hang(Hang), Options, 0), 337 Width is Right - (Indent+Hang) - RightMargin. 338line_width(_, Width, Options) :- 339 option(width(Right), Options, 72), 340 option(margin_left(Indent), Options, 0), 341 option(margin_right(RightMargin), Options, 0), 342 Width is Right - Indent - RightMargin.

348words(Text, Words) :- 349 string(Text), 350 !, 351 split_string(Text, " \n\t\r", " \n\t\r", Words0), 352 phrase(word_spaces(Words0), Words). 353words(Words, Words) :- 354 is_list(Words), 355 !. 356 357word_spaces([]) --> 358 []. 359word_spaces([""]) --> 360 !. 361word_spaces([H|T]) --> 362 { string_length(H, Len) }, 363 [ w(H, Len, []) ], 364 ( {T==[]} 365 -> [] 366 ; [b(1,_)], 367 word_spaces(T) 368 ). 369 370word_length(w(_,Len,_), Len). 371 372element_length(w(_,Len,_), Len). 373element_length(b(Len,_), Len). 374 375bullet_text(I, Bullet) :- 376 integer(I), 377 !, 378 format(string(Bullet), '~d.', [I]). 379bullet_text(Bullet, Bullet)