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, 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 ]). 38:- use_module(library(option)). 39:- use_module(library(error)). 40:- use_module(library(lists)).

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. */

72format_paragraph(Text, Options) :- 73 words(Text, Words), 74 format_lines(Words, 1, Options). 75 76format_lines([], _, _). 77format_lines(Words, LineNo, Options) :- 78 line_width(LineNo, Width, Options), 79 skip_spaces(Words, Words1), 80 take_words(Words1, 0, Width, Line0, HasBR, Words2), 81 skip_trailing_spaces(Line0, Line), 82 skip_spaces(Words2, Words3), 83 ( Words3 == [] 84 -> align_last_line(Options, OptionsLast), 85 format_line(Line, Width, LineNo, OptionsLast) 86 ; HasBR == true 87 -> align_last_line(Options, OptionsLast), 88 format_line(Line, Width, LineNo, OptionsLast), 89 LineNo1 is LineNo + 1, 90 format_lines(Words3, LineNo1, Options) 91 ; format_line(Line, Width, LineNo, Options), 92 LineNo1 is LineNo + 1, 93 format_lines(Words3, LineNo1, Options) 94 ). 95 96take_words([br(_)|T], _, _, [], true, T) :- 97 !. 98take_words([H|T0], X, W, [H|T], BR, Rest) :- 99 element_length(H, Len), 100 X1 is X+Len, 101 ( X1 =< W 102 -> true 103 ; X == 0 % take at least one word 104 ), 105 !, 106 take_words(T0, X1, W, T, BR, Rest). 107take_words(Rest, _, _, [], false, Rest). 108 109:- public 110 trim_spaces/2. 111 112trim_spaces(Line0, Line) :- 113 skip_spaces(Line0, Line1), 114 skip_trailing_spaces(Line1, Line). 115 116skip_spaces([b(_,_)|T0], T) :- 117 !, 118 skip_spaces(T0, T). 119skip_spaces(L, L). 120 121skip_trailing_spaces(L, []) :- 122 skip_spaces(L, []), 123 !. 124skip_trailing_spaces([H|T0], [H|T]) :- 125 skip_trailing_spaces(T0, T). 126 127align_last_line(Options0, Options) :- 128 select_option(text_align(justify), Options0, Options1), 129 !, 130 Options = [text_align(left)|Options1]. 131align_last_line(Options, Options).

136format_line(Line, Width, LineNo, Options) :- 137 option(pad(Char), Options), 138 option(margin_right(MR), Options), 139 MR > 0, 140 !, 141 must_be(oneof([' ']), Char), % For now 142 format_line_(Line, Width, LineNo, Options), 143 forall(between(1, MR, _), put_char(' ')). 144format_line(Line, Width, LineNo, Options) :- 145 format_line_(Line, Width, LineNo, Options). 146 147format_line_(Line, Width, LineNo, Options) :- 148 float_right(Line, Line1, Right), 149 !, 150 trim_spaces(Line1, Line2), % TBD: Alignment with floats 151 trim_spaces(Right, Right2), 152 space_dim(Line2, _, WL), 153 space_dim(Right2, _, WR), 154 append(Line2, [b(0,Space)|Right2], Line3), 155 Space is Width - WL - WR, 156 emit_indent(LineNo, Options), 157 emit_line(Line3). 158format_line_(Line, Width, LineNo, Options) :- 159 option(text_align(justify), Options), 160 !, 161 justify(Line, Width), 162 emit_indent(LineNo, Options), 163 emit_line(Line). 164format_line_(Line, Width, LineNo, Options) :- 165 option(text_align(right), Options), 166 !, 167 flush_right(Line, Width, LineR), 168 emit_indent(LineNo, Options), 169 emit_line(LineR). 170format_line_(Line, Width, LineNo, Options) :- 171 option(text_align(center), Options), 172 option(pad(Pad), Options, _), 173 !, 174 center(Line, Width, Pad, LineR), 175 emit_indent(LineNo, Options), 176 emit_line(LineR). 177format_line_(Line, Width, LineNo, Options) :- 178 option(pad(_Char), Options), 179 !, 180 pad(Line, Width, Padded), 181 emit_indent(LineNo, Options), 182 emit_line(Padded). 183format_line_(Line, _Width, LineNo, Options) :- 184 emit_indent(LineNo, Options), 185 emit_line(Line). 186 187justify(Line, Width) :- 188 space_dim(Line, Spaces, W0), 189 Spread is Width - W0, 190 length(Spaces, SPC), 191 SPC > 0, 192 Spread > 0, 193 spread(Spread, SPC, Spaces), 194 !, 195 debug(format(justify), 'Justified ~d spaces over ~d gaps: ~p', 196 [Spread, SPC, Spaces]). 197justify(_, _). 198 199flush_right(Line, Width, [b(0,Spaces)|Line]) :- 200 space_dim(Line, _Spaces, W0), 201 Spaces is Width - W0. 202 203center(Line, Width, Pad, [b(0,Left)|Padded]) :- 204 space_dim(Line, _Spaces, W0), 205 Spaces is Width - W0, 206 Left is Spaces//2, 207 ( atom(Pad), 208 Right is Spaces - Left, 209 Right > 0 210 -> append(Line, [b(0,Right)], Padded) 211 ; Padded = Line 212 ). 213 214pad(Line, Width, Padded) :- 215 space_dim(Line, _Spaces, W0), 216 Spaces is Width - W0, 217 append(Line, [b(0,Spaces)], Padded).

224float_right(Line0, Line, Right) :- 225 member(w(_,_,Attrs), Line0), 226 memberchk(float(right), Attrs), 227 !, 228 do_float_right(Line0, Line, Right). 229 230do_float_right([], [], []). 231do_float_right([H0|T0], T, [H|R]) :- 232 float_right_word(H0, H), 233 !, 234 float_right_space(T0, T, R). 235do_float_right([H|T0], [H|T], R) :- 236 do_float_right(T0, T, R). 237 238float_right_word(w(W,L,A0), w(W,L,A)) :- 239 selectchk(float(right), A0, A). 240 241float_right_space([S|T0], T, [S|R]) :- 242 S = b(_,_), 243 !, 244 float_right_space(T0, T, R). 245float_right_space(Line, Line, []).

250space_dim(Line, Spaces, Width) :- 251 space_dim(Line, Spaces, 0, Width). 252 253space_dim([], [], Width, Width). 254space_dim([b(L,Var)|T0], [Var|T], W0, W) :- 255 !, 256 W1 is W0+L, 257 space_dim(T0, T, W1, W). 258space_dim([H|T0], T, W0, W) :- 259 word_length(H, L), 260 !, 261 W1 is W0+L, 262 space_dim(T0, T, W1, W).

269spread(Spread, SPC, Spaces) :- 270 spread_spc(SPC, Spread, Spaces). 271 272spread_spc(Cnt, Spread, [H|T]) :- 273 Cnt > 0, 274 !, 275 H is round(Spread/Cnt), 276 Cnt1 is Cnt - 1, 277 Spread1 is Spread-H, 278 spread_spc(Cnt1, Spread1, T). 279spread_spc(_, _, []).

284emit_line([]). 285emit_line([H|T]) :- 286 ( emit_line_element(H) 287 -> true 288 ; type_error(line_element, H) 289 ), 290 emit_line(T). 291 292emit_line_element(w(W,_, Attrs)) :- 293 ( Attrs = [] 294 -> write(W) 295 ; ansi_format(Attrs, '~w', [W]) 296 ). 297emit_line_element(b(Len, Extra)) :- 298 ( var(Extra) 299 -> Extra = 0 300 ; true 301 ), 302 Spaces is Len+Extra, 303 forall(between(1, Spaces, _), put_char(' ')). 304 305emit_indent(1, Options) :- 306 !, 307 option(margin_left(Indent), Options, 0), 308 option(hang(Hang), Options, 0), 309 ( option(bullet(BulletSpec), Options) 310 -> bullet_text(BulletSpec, Bullet), 311 atom_length(Bullet, BLen), 312 TheIndent is Indent+Hang-1-BLen, 313 emit_indent(TheIndent), 314 format('~w ', [Bullet]) 315 ; TheIndent is Indent+Hang, 316 emit_indent(TheIndent) 317 ). 318emit_indent(_, Options) :- 319 option(margin_left(Indent), Options, 0), 320 nl, 321 emit_indent(Indent). 322 323emit_indent(N) :- 324 forall(between(1, N, _), 325 put_char(' ')). 326 327line_width(1, Width, Options) :- 328 !, 329 option(width(Right), Options, 72), 330 option(margin_left(Indent), Options, 0), 331 option(margin_right(RightMargin), Options, 0), 332 option(hang(Hang), Options, 0), 333 Width is Right - (Indent+Hang) - RightMargin. 334line_width(_, Width, Options) :- 335 option(width(Right), Options, 72), 336 option(margin_left(Indent), Options, 0), 337 option(margin_right(RightMargin), Options, 0), 338 Width is Right - Indent - RightMargin.

344words(Text, Words) :- 345 string(Text), 346 !, 347 split_string(Text, " \n\t\r", " \n\t\r", Words0), 348 phrase(word_spaces(Words0), Words). 349words(Words, Words) :- 350 is_list(Words), 351 !. 352 353word_spaces([]) --> 354 []. 355word_spaces([""]) --> 356 !. 357word_spaces([H|T]) --> 358 { string_length(H, Len) }, 359 [ w(H, Len, []) ], 360 ( {T==[]} 361 -> [] 362 ; [b(1,_)], 363 word_spaces(T) 364 ). 365 366word_length(w(_,Len,_), Len). 367 368element_length(w(_,Len,_), Len). 369element_length(b(Len,_), Len). 370 371bullet_text(I, Bullet) :- 372 integer(I), 373 !, 374 format(string(Bullet), '~d.', [I]). 375bullet_text(Bullet, Bullet)