1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 |
------------------------------------------------------------------------------ --- This library provides pretty printing combinators. --- The interface is that of --- [Daan Leijen's library](<http://www.cs.uu.nl/~daan/download/pprint/pprint.html) --- [linear-time, bounded implementation](http://www.cs.kent.ac.uk/pubs/2006/2381/index.html) --- by Olaf Chitil. --- Note that the implementation of `fill` and `fillBreak` is not linear-time bounded --- Support of ANSI escape codes for formatting and colorisation of documents --- in text terminals (see https://en.wikipedia.org/wiki/ANSI_escape_code) --- --- @author Sebastian Fischer, Bjoern Peemoeller, Jan Tikovsky --- @version September 2015 --- @category general ------------------------------------------------------------------------------ module Pretty ( -- pretty printer and document type Doc, pPrint, pretty, -- basic document combinators empty, isEmpty, text, linesep, line, linebreak, group, softline, softbreak, hardline, -- alignment combinators nest, hang, align, indent, -- composition combinators combine, (<>), (<+>), ($$), (<$+$>), (</>), (<$$>), (<//>), (<$!$>), -- list combinators compose, hsep, vsep, vsepBlank, fillSep, sep, hcat, vcat, fillCat, cat, punctuate, encloseSep, encloseSepSpaced, hEncloseSep, fillEncloseSep, fillEncloseSepSpaced, list, listSpaced, set, setSpaced, tupled, tupledSpaced, semiBraces, semiBracesSpaced, -- bracketing combinators enclose, squotes, dquotes, bquotes, parens, parensIf, angles, braces, brackets, -- fillers fill, fillBreak, -- primitive type documents char, string, int, float, -- character documents lparen, rparen, langle, rangle, lbrace, rbrace, lbracket, rbracket, squote, dquote, semi, colon, comma, space, dot, backslash, equals, larrow, rarrow, doubleArrow, doubleColon, bar, at, tilde, -- formatting combinators bold, faint, blinkSlow, blinkRapid, italic, underline, crossout, inverse, -- colorisation combinators black, red, green, yellow, blue, magenta, cyan, white, bgBlack, bgRed, bgGreen, bgYellow, bgBlue, bgMagenta, bgCyan, bgWhite ) where import qualified Dequeue as Q (Queue, cons, empty, matchHead, matchLast) infixl 5 $$, <$$>, </>, <//>, <$!$>, <$+$> infixl 6 <>, <+> --- Standard printing with a column length of 80. pPrint :: Doc -> String pPrint = pretty 80 --- The abstract data type Doc represents pretty documents. data Doc = Doc (Tokens -> Tokens) --- Extract the internal representation from a document. deDoc :: Doc -> Tokens -> Tokens deDoc (Doc d) = d --- The empty document --- @return an empty document empty :: Doc empty = Doc Empty --- Is the document empty? isEmpty :: Doc -> Bool isEmpty (Doc d) = isEmptyText (d EOD) where isEmptyText t = case t of Empty EOD -> True _ -> False --- The document `(text s)` contains the literal string `s`. --- The string shouldn't contain any newline ('\n') characters. --- If the string contains newline characters, --- the function `string` should be used. --- @param s - a string without newline (`'\n'`) characters --- @return a document which contains the literal string text :: String -> Doc text s = Doc (Text s) --- The document `(linesep s)` advances to the next line and indents --- to the current nesting level. Document `(linesep s)` --- behaves like `(text s)` if the line break is undone by `group`. --- @param s - a string --- @return a document which advances to the next line or behaves --- like `(text s)` linesep :: String -> Doc linesep = Doc . LineBreak . Just --- The document `hardline` advances to the next line and indents --- to the current nesting level. `hardline` cannot be undone by `group`. --- @return a document which advances to the next line hardline :: Doc hardline = Doc (LineBreak Nothing) --- The document `line` advances to the next line and indents to the current --- nesting level. Document `line` behaves like `(text " ")` if the line break --- is undone by `group`. --- @return a document which advances to the next line or behaves --- like `(text " ")` line :: Doc line = linesep " " --- The document `linebreak` advances to the next line and indents to --- the current nesting level. Document `linebreak` behaves like `(text "")` --- if the line break is undone by `group`. --- @return a document which advances to the next line or behaves like --- `(text "")` linebreak :: Doc linebreak = linesep "" --- The document `softline` behaves like `space` if the resulting output --- fits the page, otherwise it behaves like `line`. --- `softline = group line` --- @return a document which behaves like `space` or `line` softline :: Doc softline = group line --- The document `softbreak` behaves like `(text "")` if the resulting output --- fits the page, otherwise it behaves like `line`. --- `softbreak = group linebreak` --- @return a document which behaves like `(text "")` or `line` softbreak :: Doc softbreak = group linebreak --- The combinator `group` is used to specify alternative layouts. --- The document `(group x)` undoes all line breaks in document `x`. --- The resulting line is added to the current line if that fits the page. --- Otherwise, the document `x` is rendered without any changes. --- @param d - a document --- @return document d without line breaks if that fits the page. group :: Doc -> Doc group d = Doc (OpenGroup . deDoc d . CloseGroup) --- The document `(nest i d)` renders document `d` with the current --- indentation level increased by `i` (See also `hang`, --- `align` and `indent`). --- --- nest 2 (text "hello" $$ text "world") $$ text "!" --- --- outputs as: --- --- hello --- world --- ! --- --- @param i - an integer which increases the indentation level --- @param d - a document --- @return document d with an indentation level increased by i nest :: Int -> Doc -> Doc nest i d = Doc (OpenNest (Inc i) . deDoc d . CloseNest) --- The combinator `hang` implements hanging indentation. --- The document `(hang i d)` renders document `d` with a nesting level set --- to the current column plus `i`. The following example uses hanging --- indentation for some text: --- --- test = hang 4 --- (fillSep --- (map text --- (words "the hang combinator indents these words !"))) --- --- Which lays out on a page with a width of 20 characters as: --- --- the hang combinator --- indents these --- words ! --- --- The hang combinator is implemented as: --- --- hang i x = align (nest i x) --- --- @param i - an integer which increases the indentation level --- @param d - a document --- @return document d with an indentation level set to the current column plus i hang :: Int -> Doc -> Doc hang i x = align (nest i x) --- The document `(align d)` renders document `d with the nesting level --- set to the current column. It is used for example to implement `hang`. --- --- As an example, we will put a document right above another one, --- regardless of the current nesting level: --- --- x $$ y = align (x $$ y) --- test = text "hi" <+> (text "nice" $$ text "world") --- --- which will be layed out as: --- --- hi nice --- world --- --- @param d - a document --- @return document d with the nesting level set to the current column align :: Doc -> Doc align d = Doc (OpenNest Align . deDoc d . CloseNest) --- The document `(indent i d)` indents document `d` with `i` spaces. --- --- test = indent 4 (fillSep (map text --- (words "the indent combinator indents these words !"))) --- --- Which lays out with a page width of 20 as: --- --- the indent --- combinator --- indents these --- words ! --- --- @param i - an integer which increases the indentation level --- @param d - a document --- @return document d with an indentation level set to the current column --- plus i indent :: Int -> Doc -> Doc indent i d = hang i (spaces i <> d) --- The document `(combine c d1 d2)` combines document `d1` and `d2` with --- document `c` in between using `(<>)` with identity `empty`. --- Thus, the following equations hold. --- --- combine c d1 empty == d1 --- combine c empty d2 == d2 --- combine c d1 d2 == d1 <> c <> d2 if neither d1 nor d2 are empty --- --- @param c - the middle document --- @param d1 - the left document --- @param d2 - the right document --- @return concatenation of d1 and d2 with c in between unless one --- of the documents is empty combine :: Doc -> Doc -> Doc -> Doc combine c d1 d2 | isEmpty d1 = d2 | isEmpty d2 = d1 | otherwise = enclose d1 d2 c --- The document `(x <> y)` concatenates document `x` and document `y`. --- It is an associative operation having `empty` as a left and right unit. --- @param x - the first document --- @param y - the second document --- @return concatenation of x and y without seperator with identity empty (<>) :: Doc -> Doc -> Doc d1 <> d2 | isEmpty d1 = d2 | isEmpty d2 = d1 | otherwise = Doc (deDoc d1 . deDoc d2) --- The document `(x <+> y)` concatenates document `x` and `y` with a --- `space` in between with identity `empty`. --- @param x - the first document --- @param y - the second document --- @return concatenation of x and y with a space in between (<+>) :: Doc -> Doc -> Doc (<+>) = combine space --- The document `(x $$ y)` concatenates document x and y with a --- `line` in between with identity `empty`. --- @param x - the first document --- @param y - the second document --- @return concatenation of x and y with a line in between ($$) :: Doc -> Doc -> Doc ($$) = combine line --- The document `(x <$+$> y)` concatenates document `x` and `y` with a --- blank line in between with identity `empty`. --- @param x - the first document --- @param y - the second document --- @return concatenation of x and y with a blank line in between (<$+$>) :: Doc -> Doc -> Doc (<$+$>) = combine (line <> linebreak) --- The document `(x </> y)` concatenates document `x` and `y` with --- a `softline` in between with identity `empty`. --- This effectively puts `x` and `y` either next to each other --- (with a `space` in between) or underneath each other. --- @param x - the first document --- @param y - the second document --- @return concatenation of x and y with a softline in between (</>) :: Doc -> Doc -> Doc (</>) = combine softline --- The document `(x <$$> y)` concatenates document `x` and `y` with a --- `linebreak` in between with identity `empty`. --- @param x - the first document --- @param y - the second document --- @return concatenation of x and y with a linebreak in between (<$$>) :: Doc -> Doc -> Doc (<$$>) = combine linebreak --- The document `(x <//> y)` concatenates document `x` and `y` with a --- `softbreak` in between with identity `empty`. --- This effectively puts `x` and `y` either right next to each other --- or underneath each other. --- @param x - the first document --- @param y - the second document --- @return concatenation of x and y with a softbreak in between (<//>) :: Doc -> Doc -> Doc (<//>) = combine softbreak --- The document `(x <$!$> y)` concatenates document `x` and `y` with a --- `hardline` in between with identity `empty`. --- This effectively puts `x` and `y` underneath each other. --- @param x - the first document --- @param y - the second document --- @return concatenation of x and y with a hardline in between (<$!$>) :: Doc -> Doc -> Doc (<$!$>) = combine hardline --- The document `(compose f xs)` concatenates all documents `xs` --- with function `f`. --- Function `f` should be like `(<+>)`, `($$)` and so on. --- @param f - a combiner function --- @param xs - a list of documents --- @return concatenation of documents compose :: (Doc -> Doc -> Doc) -> [Doc] -> Doc compose _ [] = empty compose op ds@(_:_) = foldr1 op ds -- no seperator at the end --- The document `(hsep xs)` concatenates all documents `xs` --- horizontally with `(<+>)`. --- @param xs - a list of documents --- @return horizontal concatenation of documents hsep :: [Doc] -> Doc hsep = compose (<+>) --- The document `(vsep xs)` concatenates all documents `xs` vertically with --- `($$)`. If a group undoes the line breaks inserted by `vsep`, --- all documents are separated with a `space`. --- --- someText = map text (words ("text to lay out")) --- test = text "some" <+> vsep someText --- --- This is layed out as: --- --- some text --- to --- lay --- out --- --- The `align` combinator can be used to align the documents --- under their first element: --- --- test = text "some" <+> align (vsep someText) --- --- This is printed as: --- --- some text --- to --- lay --- out --- --- @param xs - a list of documents --- @return vertical concatenation of documents vsep :: [Doc] -> Doc vsep = compose ($$) --- The document `vsep xs` concatenates all documents `xs` vertically with --- `(<$+$>)`. If a group undoes the line breaks inserted by `vsepBlank`, --- all documents are separated with a `space`. --- @param xs - a list of documents --- @return vertical concatenation of documents vsepBlank :: [Doc] -> Doc vsepBlank = compose (<$+$>) --- The document `(fillSep xs)` concatenates documents `xs` horizontally with --- `(</>)` as long as its fits the page, than inserts a --- `line` and continues doing that for all documents in `xs`. --- `fillSep xs = foldr (</>) empty xs` --- @param xs - a list of documents --- @return horizontal concatenation of documents fillSep :: [Doc] -> Doc fillSep = compose (</>) --- The document `(sep xs)` concatenates all documents `xs` either horizontally --- with `(<+>)`, if it fits the page, or vertically --- with `($$)`. --- `sep xs = group (vsep xs)` --- @param xs - a list of documents --- @return horizontal concatenation of documents, if it fits the page, --- or vertical concatenation else sep :: [Doc] -> Doc sep = group . vsep --- The document `(hcat xs)` concatenates all documents `xs` horizontally --- with `(<>)`. --- @param xs - a list of documents --- @return horizontal concatenation of documents hcat :: [Doc] -> Doc hcat = compose (<>) --- The document `(vcat xs)` concatenates all documents `xs` vertically --- with `(<$$>)`. If a `group` undoes the line breaks inserted by `vcat`, --- all documents are directly concatenated. --- @param xs - a list of documents --- @return vertical concatenation of documents vcat :: [Doc] -> Doc vcat = compose (<$$>) --- The document `(fillCat xs)` concatenates documents `xs` horizontally --- with `(<//>)` as long as its fits the page, than inserts a `linebreak` --- and continues doing that for all documents in `xs`. --- `fillCat xs = foldr (<//>) empty xs` --- @param xs - a list of documents --- @return horizontal concatenation of documents fillCat :: [Doc] -> Doc fillCat = compose (<//>) --- The document `(cat xs)` concatenates all documents `xs` either horizontally --- with `(<>)`, if it fits the page, or vertically with --- `(<$$>)`. --- `cat xs = group (vcat xs)` --- @param xs - a list of documents --- @return horizontal concatenation of documents cat :: [Doc] -> Doc cat = group . vcat --- `(punctuate p xs)` concatenates all documents `xs` with document `p` except --- for the last document. --- --- someText = map text ["words","in","a","tuple"] --- test = parens (align (cat (punctuate comma someText))) --- --- This is layed out on a page width of 20 as: --- --- (words,in,a,tuple) --- --- But when the page width is 15, it is layed out as: --- --- (words, --- in, --- a, --- tuple) --- --- (If you want put the commas in front of their elements instead of at the --- end, you should use `tupled` or, in general, `encloseSep`.) --- @param p - a document as seperator --- @param xs - a list of documents --- @return concatenation of documents with p in between punctuate :: Doc -> [Doc] -> [Doc] punctuate d ds = go ds where go [] = [] go [x] = [x] go (x:xs@(_:_)) = (x <> d) : go xs --- The document `(encloseSep l r s xs)` concatenates the documents `xs` --- seperated by `s` and encloses the resulting document by `l` and `r`. --- The documents are rendered horizontally if that fits the page. Otherwise --- they are aligned vertically. All seperators are put in front of the --- elements. --- --- For example, the combinator `list` can be defined with `encloseSep`: --- --- list xs = encloseSep lbracket rbracket comma xs --- test = text "list" <+> (list (map int [10,200,3000])) --- --- Which is layed out with a page width of 20 as: --- --- list [10,200,3000] --- --- But when the page width is 15, it is layed out as: --- --- list [10 --- ,200 --- ,3000] --- --- @param l - left document --- @param r - right document --- @param s - a document as seperator --- @param xs - a list of documents --- @return concatenation of l, xs (with s in between) and r encloseSep :: Doc -> Doc -> Doc -> [Doc] -> Doc encloseSep l r _ [] = l <> r encloseSep l r s (d:ds) = align (enclose l r (cat (d : map (s <>) ds))) --- The document `(encloseSepSpaced l r s xs)` concatenates the documents `xs` --- seperated by `s` and encloses the resulting document by `l` and `r`. --- In addition, after each occurrence of `s`, after `l`, and before `r`, --- a `space` is inserted. --- The documents are rendered horizontally if that fits the page. Otherwise --- they are aligned vertically. All seperators are put in front of the --- elements. --- --- @param l - left document --- @param r - right document --- @param s - a document as seperator --- @param xs - a list of documents --- @return concatenation of l, xs (with s in between) and r encloseSepSpaced :: Doc -> Doc -> Doc -> [Doc] -> Doc encloseSepSpaced l r s = encloseSep (l <> space) (space <> r) (s <> space) --- The document `(hEncloseSep l r s xs)` concatenates the documents `xs` --- seperated by `s` and encloses the resulting document by `l` and `r`. --- --- The documents are rendered horizontally. --- @param l - left document --- @param r - right document --- @param s - a document as seperator --- @param xs - a list of documents --- @return concatenation of l, xs (with s in between) and r hEncloseSep :: Doc -> Doc -> Doc -> [Doc] -> Doc hEncloseSep l r _ [] = l <> r hEncloseSep l r s (d:ds) = align (enclose l r (hcat (d : map (s <>) ds))) --- The document `(fillEncloseSep l r s xs)` concatenates the documents `xs` --- seperated by `s` and encloses the resulting document by `l` and `r`. --- --- The documents are rendered horizontally if that fits the page. --- Otherwise they are aligned vertically. --- All seperators are put in front of the elements. --- @param l - left document --- @param r - right document --- @param s - a document as seperator --- @param xs - a list of documents --- @return concatenation of l, xs (with s in between) and r fillEncloseSep :: Doc -> Doc -> Doc -> [Doc] -> Doc fillEncloseSep l r _ [] = l <> r fillEncloseSep l r s (d:ds) = align (enclose l r (fillCat (d : map (s <>) ds))) --- The document `(fillEncloseSepSpaced l r s xs)` concatenates the documents --- `xs` seperated by `s` and encloses the resulting document by `l` and `r`. --- In addition, after each occurrence of `s`, after `l`, and before `r`, --- a `space` is inserted. --- --- The documents are rendered horizontally if that fits the page. --- Otherwise, they are aligned vertically. --- All seperators are put in front of the elements. --- @param l - left document --- @param r - right document --- @param s - a document as seperator --- @param xs - a list of documents --- @return concatenation of l, xs (with s in between) and r fillEncloseSepSpaced :: Doc -> Doc -> Doc -> [Doc] -> Doc fillEncloseSepSpaced l r s = fillEncloseSep (l <> space) (space <> r) (s <> space) --- The document `(list xs)` comma seperates the documents `xs` and encloses --- them in square brackets. The documents are rendered horizontally if --- that fits the page. Otherwise they are aligned vertically. --- All comma seperators are put in front of the elements. --- @param xs - a list of documents --- @return comma seperated documents xs and enclosed in square brackets list :: [Doc] -> Doc list = encloseSep lbracket rbracket comma --- Spaced version of `list` listSpaced :: [Doc] -> Doc listSpaced = encloseSepSpaced lbracket rbracket comma --- The document `(set xs)` comma seperates the documents `xs` and encloses --- them in braces. The documents are rendered horizontally if --- that fits the page. Otherwise they are aligned vertically. --- All comma seperators are put in front of the elements. --- @param xs - a list of documents --- @return comma seperated documents xs and enclosed in braces set :: [Doc] -> Doc set = encloseSep lbrace rbrace comma --- Spaced version of `set` setSpaced :: [Doc] -> Doc setSpaced = encloseSepSpaced lbrace rbrace comma --- The document `(tupled xs)` comma seperates the documents `xs` and encloses --- them in parenthesis. The documents are rendered horizontally if that fits --- the page. Otherwise they are aligned vertically. --- All comma seperators are put in front of the elements. --- @param xs - a list of documents --- @return comma seperated documents xs and enclosed in parenthesis tupled :: [Doc] -> Doc tupled = encloseSep lparen rparen comma --- Spaced version of `tupled` tupledSpaced :: [Doc] -> Doc tupledSpaced = encloseSepSpaced lparen rparen comma --- The document `(semiBraces xs)` seperates the documents `xs` with semi colons --- and encloses them in braces. The documents are rendered horizontally --- if that fits the page. Otherwise they are aligned vertically. --- All semi colons are put in front of the elements. --- @param xs - a list of documents --- @return documents xs seperated with semi colons and enclosed in braces semiBraces :: [Doc] -> Doc semiBraces = encloseSep lbrace rbrace semi --- Spaced version of `semiBraces` semiBracesSpaced :: [Doc] -> Doc semiBracesSpaced = encloseSepSpaced lbrace rbrace semi --- The document `(enclose l r x)` encloses document `x` between --- documents `l` and `r` using `(<>)`. --- `enclose l r x = l <> x <> r` --- @param l - the left document --- @param r - the right document --- @param x - the middle document --- @return concatenation of l, x and r enclose :: Doc -> Doc -> Doc -> Doc enclose l r d = l <> d <> r --- Document `(squotes x)` encloses document `x` with single quotes `"'"`. --- @param x - a document --- @return document x enclosed by single quotes squotes :: Doc -> Doc squotes = enclose squote squote --- Document `(dquotes x)` encloses document `x` with double quotes. --- @param x - a document --- @return document x enclosed by double quotes dquotes :: Doc -> Doc dquotes = enclose dquote dquote --- Document `(bquotes x)` encloses document `x` with back quotes `"\`"`. --- @param x - a document --- @return document x enclosed by `\`` quotes bquotes :: Doc -> Doc bquotes = enclose bquote bquote --- Document `(parens x)` encloses document `x` in parenthesis, --- `"("` and `")"`. --- @param x - a document --- @return document x enclosed in parenthesis parens :: Doc -> Doc parens = enclose lparen rparen --- Document `(parensIf x)` encloses document `x` in parenthesis,`"("` and `")"`, --- iff the condition is true. --- @param x - a document --- @return document x enclosed in parenthesis iff the condition is true parensIf :: Bool -> Doc -> Doc parensIf b s = if b then parens s else s --- Document `(angles x)` encloses document `x` in angles, `"<"` and `">"`. --- @param x - a document --- @return document x enclosed in angles angles :: Doc -> Doc angles = enclose langle rangle --- Document `(braces x)` encloses document `x` in braces, `"{"` and `"}"`. --- @param x - a document --- @return document x enclosed in braces braces :: Doc -> Doc braces = enclose lbrace rbrace --- Document `(brackets x)` encloses document `x` in square brackets, --- `"["` and `"]"`. --- @param x - a document --- @return document x enclosed in square brackets brackets :: Doc -> Doc brackets = enclose lbracket rbracket --- The document `(char c)` contains the literal character `c`. --- The character should not be a newline (`\n`), --- the function `line` should be used for line breaks. --- @param c - a character (not `\n`) --- @return a document which contains the literal character c char :: Char -> Doc char c = text [c] --- The document `(string s)` concatenates all characters in `s` using --- `line` for newline characters and `char` for all other characters. --- It is used instead of `text` whenever the text contains newline characters. --- @param s - a string --- @return a document which contains the string s string :: String -> Doc string = hcat . map (\c -> if elem c ['\n','\r'] then line else char c) --- The document `(int i)` shows the literal integer `i` using `text`. --- @param i - an integer --- @return a document which contains the integer i int :: Int -> Doc int n = text (show n) --- The document `(float f)` shows the literal float `f` using `text`. --- @param f - a float --- @return a document which contains the float f float :: Float -> Doc float x = text (show x) --- The document `lparen` contains a left parenthesis, `"("`. --- @return a document which contains a left parenthesis lparen :: Doc lparen = char '(' --- The document `rparen` contains a right parenthesis, `")"`. --- @return a document which contains a right parenthesis rparen :: Doc rparen = char ')' --- The document `langle` contains a left angle, `"<"`. --- @return a document which contains a left angle langle :: Doc langle = char '<' --- The document `rangle` contains a right angle, `">"`. --- @return a document which contains a right angle rangle :: Doc rangle = char '>' --- The document `lbrace` contains a left brace, `"{"`. --- @return a document which contains a left brace lbrace :: Doc lbrace = char '{' --- The document `rbrace` contains a right brace, `"}"`. --- @return a document which contains a right brace rbrace :: Doc rbrace = char '}' --- The document `lbracket` contains a left square bracket, `"["`. --- @return a document which contains a left square bracket lbracket :: Doc lbracket = char '[' --- The document `rbracket` contains a right square bracket, `"]"`. --- @return a document which contains a right square bracket rbracket :: Doc rbracket = char ']' --- The document `squote` contains a single quote, `"'"`. --- @return a document which contains a single quote squote :: Doc squote = char '\'' --- The document `dquote` contains a double quote. --- @return a document which contains a double quote dquote :: Doc dquote = char '"' --- The document `dquote` contains a `'`'` quote. --- @return a document which contains a `'`'` quote bquote :: Doc bquote = char '`' --- The document `semi` contains a semi colon, `";"`. --- @return a document which contains a semi colon semi :: Doc semi = char ';' --- The document `colon` contains a colon, `":"`. --- @return a document which contains a colon colon :: Doc colon = char ':' --- The document `comma` contains a comma, `","`. --- @return a document which contains a comma comma :: Doc comma = char ',' --- The document `space` contains a single space, `" "`. --- --- x <+> y = x <> space <> y --- --- @return a document which contains a single space space :: Doc space = char ' ' --- The document `(spaces n)` contains `n` spaces, when `n` is greater than 0. --- Otherwise the document is empty. --- --- @return a document which contains n spaces or the empty document, --- if n <= 0 spaces :: Int -> Doc spaces n | n <= 0 = empty | otherwise = text $ replicate n ' ' --- The document `dot` contains a single dot, `"."`. --- @return a document which contains a single dot dot :: Doc dot = char '.' --- The document `backslash` contains a back slash, `"\\"`. --- @return a document which contains a back slash backslash :: Doc backslash = char '\\' --- The document `equals` contains an equal sign, `"="`. --- @return a document which contains an equal equals :: Doc equals = char '=' --- The document `larrow` contains a left arrow sign, `"<-"`. --- @return a document which contains a left arrow sign larrow :: Doc larrow = text "<-" --- The document `rarrow` contains a right arrow sign, `"->"`. --- @return a document which contains a right arrow sign rarrow :: Doc rarrow = text "->" --- The document `doubleArrow` contains an double arrow sign, `"=>"`. --- @return a document which contains an double arrow sign doubleArrow :: Doc doubleArrow = text "=>" --- The document `doubleColon` contains a double colon sign, `"::"`. --- @return a document which contains a double colon sign doubleColon :: Doc doubleColon = text "::" --- The document `bar` contains a vertical bar sign, `"|"`. --- @return a document which contains a vertical bar sign bar :: Doc bar = char '|' --- The document `at` contains an at sign, `"@"`. --- @return a document which contains an at sign at :: Doc at = char '@' --- The document `tilde` contains a tilde sign, `"~"`. --- @return a document which contains a tilde sign tilde :: Doc tilde = char '~' --- The document `(fill i d)` renders document `d`. It than appends --- `space`s until the width is equal to `i`. If the width of `d` is --- already larger, nothing is appended. This combinator is quite --- useful in practice to output a list of bindings. The following --- example demonstrates this. --- --- types = [("empty","Doc") --- ,("nest","Int -> Doc -> Doc") --- ,("linebreak","Doc")] --- --- ptype (name,tp) --- = fill 6 (text name) <+> text "::" <+> text tp --- --- test = text "let" <+> align (vcat (map ptype types)) --- --- Which is layed out as: --- --- let empty :: Doc --- nest :: Int -> Doc -> Doc --- linebreak :: Doc --- --- Note that `fill` is not guaranteed to be linear-time bounded since it has to --- compute the width of a document before pretty printing it fill :: Int -> Doc -> Doc fill i d = d <> fill' where w = width d fill' = if w >= i then empty else spaces (i - w) --- The document `(fillBreak i d)` first renders document `d`. It --- than appends `space`s until the width is equal to `i`. If the --- width of `d` is already larger than `i`, the nesting level is --- increased by `i` and a `line` is appended. When we redefine `ptype` --- in the previous example to use `fillBreak`, we get a useful --- variation of the previous output: --- --- ptype (name,tp) --- = fillBreak 6 (text name) <+> text "::" <+> text tp --- --- The output will now be: --- --- let empty :: Doc --- nest :: Int -> Doc -> Doc --- linebreak --- :: Doc --- --- Note that `fillBreak` is not guaranteed to be linear-time bounded since it --- has to compute the width of a document before pretty printing it fillBreak :: Int -> Doc -> Doc fillBreak i d = d <> fill' where w = width d fill' = if w >= i then nest i linebreak else spaces (i - w) --- Compute the width of a given document width :: Doc -> Int width (Doc d) = width' 0 (d EOD) where width' w EOD = w width' w (Empty ts) = width' w ts width' w (Text s ts) = width' (w + length s) ts width' w (LineBreak Nothing ts) = width' w ts width' w (LineBreak (Just s) ts) = width' (w + length s) ts width' w (OpenGroup ts) = width' w ts width' w (CloseGroup ts) = width' w ts width' w (OpenNest _ ts) = width' w ts width' w (CloseNest ts) = width' w ts width' w (OpenFormat _ ts) = width' w ts width' w (CloseFormat ts) = width' w ts -- ----------------------------------------------------------------------------- -- Formatting combinators -- ----------------------------------------------------------------------------- --- The document `(bold d)` displays document `d` with bold text --- @param d - a document --- @return document d displayed with bold text bold :: Doc -> Doc bold d = Doc (OpenFormat (SetIntensity Bold) . deDoc d . CloseFormat) --- The document `(faint d)` displays document `d` with faint text --- @param d - a document --- @return document d displayed with faint text faint :: Doc -> Doc faint d = Doc (OpenFormat (SetIntensity Faint) . deDoc d . CloseFormat) --- The document `(blinkSlow d)` displays document `d` with slowly blinking text --- (rarely supported) --- @param d - a document --- @return document d displayed with slowly blinking text blinkSlow :: Doc -> Doc blinkSlow d = Doc (OpenFormat (SetBlinkMode Slow) . deDoc d . CloseFormat) --- The document `(blinkRapid d)` displays document `d` with rapidly blinking --- text (rarely supported) --- @param d - a document --- @return document d displayed with rapidly blinking text blinkRapid :: Doc -> Doc blinkRapid d = Doc (OpenFormat (SetBlinkMode Rapid) . deDoc d . CloseFormat) --- The document `(italic d)` displays document `d` with italicized text --- (rarely supported) --- @param d - a document --- @return document d displayed with italicized text italic :: Doc -> Doc italic d = Doc (OpenFormat (SetItalicized True) . deDoc d . CloseFormat) --- The document `(underline d)` displays document `d` with underlined text --- @param d - a document --- @return document d displayed with underlined text underline :: Doc -> Doc underline d = Doc (OpenFormat (SetUnderlined True) . deDoc d . CloseFormat) --- The document `(crossout d)` displays document `d` with crossed out text --- @param d - a document --- @return document d displayed with crossed out text crossout :: Doc -> Doc crossout d = Doc (OpenFormat (SetCrossedout True) . deDoc d . CloseFormat) --- The document `(inverse d)` displays document `d` with inversed coloring, --- i.e. use text color of `d` as background color and background color of `d` --- as text color --- @param d - a document --- @return document d displayed with inversed coloring inverse :: Doc -> Doc inverse d = Doc (OpenFormat (InverseColoring True) . deDoc d . CloseFormat) -- ----------------------------------------------------------------------------- -- Colorisation combinators -- ----------------------------------------------------------------------------- -- foreground colors --- The document `(black d)` displays document `d` with black text color --- @param d - a document --- @return document d displayed with black text color black :: Doc -> Doc black d = Doc (OpenFormat (SetForeground Black) . deDoc d . CloseFormat) --- The document `(red d)` displays document `d` with red text color --- @param d - a document --- @return document d displayed with red text color red :: Doc -> Doc red d = Doc (OpenFormat (SetForeground Red) . deDoc d . CloseFormat) --- The document `(green d)` displays document `d` with green text color --- @param d - a document --- @return document d displayed with green text color green :: Doc -> Doc green d = Doc (OpenFormat (SetForeground Green) . deDoc d . CloseFormat) --- The document `(yellow d)` displays document `d` with yellow text color --- @param d - a document --- @return document d displayed with yellow text color yellow :: Doc -> Doc yellow d = Doc (OpenFormat (SetForeground Yellow) . deDoc d . CloseFormat) --- The document `(blue d)` displays document `d` with blue text color --- @param d - a document --- @return document d displayed with blue text color blue :: Doc -> Doc blue d = Doc (OpenFormat (SetForeground Blue) . deDoc d . CloseFormat) --- The document `(magenta d)` displays document `d` with magenta text color --- @param d - a document --- @return document d displayed with magenta text color magenta :: Doc -> Doc magenta d = Doc (OpenFormat (SetForeground Magenta) . deDoc d . CloseFormat) --- The document `(cyan d)` displays document `d` with cyan text color --- @param d - a document --- @return document d displayed with cyan text color cyan :: Doc -> Doc cyan d = Doc (OpenFormat (SetForeground Cyan) . deDoc d . CloseFormat) --- The document `(white d)` displays document `d` with white text color --- @param d - a document --- @return document d displayed with white text color white :: Doc -> Doc white d = Doc (OpenFormat (SetForeground White) . deDoc d . CloseFormat) -- background colors --- The document `(bgBlack d)` displays document `d` with black background color --- @param d - a document --- @return document d displayed with black background color bgBlack :: Doc -> Doc bgBlack d = Doc (OpenFormat (SetBackground Black) . deDoc d . CloseFormat) --- The document `(bgRed d)` displays document `d` with red background color --- @param d - a document --- @return document d displayed with red background color bgRed :: Doc -> Doc bgRed d = Doc (OpenFormat (SetBackground Red) . deDoc d . CloseFormat) --- The document `(bgGreen d)` displays document `d` with green background color --- @param d - a document --- @return document d displayed with green background color bgGreen :: Doc -> Doc bgGreen d = Doc (OpenFormat (SetBackground Green) . deDoc d . CloseFormat) --- The document `(bgYellow d)` displays document `d` with yellow background --- color --- @param d - a document --- @return document d displayed with yellow background color bgYellow :: Doc -> Doc bgYellow d = Doc (OpenFormat (SetBackground Yellow) . deDoc d . CloseFormat) --- The document `(bgBlue d)` displays document `d` with blue background color --- @param d - a document --- @return document d displayed with blue background color bgBlue :: Doc -> Doc bgBlue d = Doc (OpenFormat (SetBackground Blue) . deDoc d . CloseFormat) --- The document `(bgMagenta d)` displays document `d` with magenta background --- color --- @param d - a document --- @return document d displayed with magenta background color bgMagenta :: Doc -> Doc bgMagenta d = Doc (OpenFormat (SetBackground Magenta) . deDoc d . CloseFormat) --- The document `(bgCyan d)` displays document `d` with cyan background color --- @param d - a document --- @return document d displayed with cyan background color bgCyan :: Doc -> Doc bgCyan d = Doc (OpenFormat (SetBackground Cyan) . deDoc d . CloseFormat) --- The document `(bgWhite d)` displays document `d` with white background color --- @param d - a document --- @return document d displayed with white background color bgWhite :: Doc -> Doc bgWhite d = Doc (OpenFormat (SetBackground White) . deDoc d . CloseFormat) -- ----------------------------------------------------------------------------- -- Implementation -- ----------------------------------------------------------------------------- type Horizontal = Bool type Remaining = Int type Width = Int type Position = Int type StartPosition = Position type EndPosition = Position type Out = Remaining -> Margins -> FormatHistory -> String -- Type of a `group output function`: Takes information whether group content -- should be formatted horizontally or vertically and a continuation to output -- parts of the document which come after the group type OutGroupPrefix = Horizontal -> Out -> Out type Margins = [Int] -- A nesting is either an alignment or a relative indentation data Nesting = Align | Inc Int -- text colorisation data Color = Black | Red | Green | Yellow | Blue | Magenta | Cyan | White | Default -- console intensity data Intensity = Faint | Normal | Bold -- support of blinking text data BlinkMode = Off | Slow | Rapid -- text formatting statement data FormatStm = SetForeground Color | SetBackground Color | SetIntensity Intensity | SetBlinkMode BlinkMode | SetItalicized Bool | SetUnderlined Bool | SetCrossedout Bool | InverseColoring Bool type FormatHistory = [FormatStm] resetFormat :: FormatHistory -> (FormatStm, FormatHistory) resetFormat [] = error "Pretty.resetFormat2: illegal format history" resetFormat (stm:stms) = case stm of SetForeground _ -> (SetForeground (prevFGColor stms), stms) SetBackground _ -> (SetBackground (prevBGColor stms), stms) SetIntensity _ -> (SetIntensity (prevIntensity stms), stms) SetBlinkMode _ -> (SetBlinkMode (prevBlinkMode stms), stms) SetItalicized b -> (SetItalicized (not b), stms) SetUnderlined b -> (SetUnderlined (not b), stms) SetCrossedout b -> (SetCrossedout (not b), stms) InverseColoring b -> (InverseColoring (not b), stms) -- Find previous foreground color in history prevFGColor :: FormatHistory -> Color prevFGColor history = case history of [] -> Default (SetForeground c : _ ) -> c (_ : hs) -> prevFGColor hs -- Find previous background color in history prevBGColor :: FormatHistory -> Color prevBGColor history = case history of [] -> Default (SetBackground c : _ ) -> c (_ : hs) -> prevBGColor hs -- Find previous text intensity in history prevIntensity :: FormatHistory -> Intensity prevIntensity history = case history of [] -> Normal (SetIntensity i : _ ) -> i (_ : hs) -> prevIntensity hs -- Find previous blinking mode in history prevBlinkMode :: FormatHistory -> BlinkMode prevBlinkMode history = case history of [] -> Off (SetBlinkMode b : _ ) -> b (_ : hs) -> prevBlinkMode hs applyFormat :: FormatStm -> String applyFormat (SetForeground c) = txtMode (colorMode c) applyFormat (SetBackground c) = txtMode (colorMode c + 10) applyFormat (SetIntensity i) = txtMode (intensityMode i) applyFormat (SetBlinkMode b) = txtMode (blinkMode b) applyFormat (SetItalicized b) = txtMode (if b then 3 else 23) applyFormat (SetUnderlined b) = txtMode (if b then 4 else 24) applyFormat (SetCrossedout b) = txtMode (if b then 9 else 29) applyFormat (InverseColoring b) = txtMode (if b then 7 else 27) -- Text mode txtMode :: Int -> String txtMode m = csiCmd ++ show m ++ "m" where csiCmd :: String csiCmd = '\ESC' : '[' : "" -- Color mode colorMode :: Color -> Int colorMode c = case c of Black -> 30 Red -> 31 Green -> 32 Yellow -> 33 Blue -> 34 Magenta -> 35 Cyan -> 36 White -> 37 Default -> 39 -- Intensity mode intensityMode :: Intensity -> Int intensityMode i = case i of Faint -> 2 Normal -> 22 Bold -> 1 -- Blink mode blinkMode :: BlinkMode -> Int blinkMode b = case b of Off -> 25 Slow -> 5 Rapid -> 6 -- Token sequence. Note that the data type linearizes a document so that -- a fragment is usually followed by a remaining document. data Tokens = EOD -- end of document | Empty Tokens -- empty document | Text String Tokens -- string | LineBreak (Maybe String) Tokens -- linebreak that will be replaced by the -- separator if the linebreak is undone | OpenGroup Tokens -- Beginning of a group | CloseGroup Tokens -- End of a group | OpenNest Nesting Tokens -- Beginning of a nesting | CloseNest Tokens -- End of a nesting | OpenFormat FormatStm Tokens -- Beginning of a formatting statement | CloseFormat Tokens -- End of a formatting statement applyNesting :: Nesting -> Width -> Remaining -> Margins -> Margins applyNesting Align w r ms = (w - r) : ms applyNesting (Inc i) _ _ ms = case ms of m:_ -> (m + i) : ms _ -> error "Pretty.applyNesting: empty margin list" unApplyNesting :: Margins -> Margins unApplyNesting [] = error "Pretty.unApplyNesting: empty margin list" unApplyNesting (_:ms) = ms addSpaces :: Int -> Tokens -> String addSpaces m ts = case ts of LineBreak _ _ -> "" EOD -> "" Empty ts' -> addSpaces m ts' OpenGroup ts' -> addSpaces m ts' CloseGroup ts' -> addSpaces m ts' OpenNest _ ts' -> addSpaces m ts' CloseNest ts' -> addSpaces m ts' OpenFormat _ ts' -> addSpaces m ts' CloseFormat ts' -> addSpaces m ts' Text _ _ -> replicate m ' ' -- Normalise a token sequence using the following rewriting rules: -- -- CloseGroup (Text s ts) => Text s (CloseGroup ts) -- OpenGroup (Text s ts) => Text s (OpenGroup ts) -- OpenGroup (CloseGroup ts) => ts -- -- Rewriting moves `Text` tokens in and out of groups. The set of `lines` -- "belonging" to each group, i.e., the set of layouts, is left unchanged. normalise :: Tokens -> Tokens normalise = go id where go co EOD = co EOD go co (Empty ts) = go co ts -- there should be no deferred opening brackets go co (OpenGroup ts) = go (co . open) ts go co (CloseGroup ts) = go (co . CloseGroup) ts go co (LineBreak ms ts) = (co . LineBreak ms . go id) ts go co (Text s ts) = Text s (go co ts) go co (OpenNest n ts) = OpenNest n (go co ts) go co (CloseNest ts) = CloseNest (go co ts) go co (OpenFormat f ts) = OpenFormat f (go co ts) go co (CloseFormat ts) = CloseFormat (go co ts) open t = case t of CloseGroup ts -> ts _ -> OpenGroup t -- Transform a document into a group-closed document by normalising its token -- sequence. -- A document is called group-closed, if between the end of every `group` and -- the next `text` document there is always a `line` document. doc2Tokens :: Doc -> Tokens doc2Tokens (Doc d) = normalise (d EOD) --- `(pretty w d)` pretty prints document `d` with a page width of `w` characters --- @param w - width of page --- @param d - a document --- @return pretty printed document pretty :: Width -> Doc -> String pretty w d = noGroup (doc2Tokens d) w 1 w [0] [] -- Compute number of visible ASCII characters length :: String -> Int length = Prelude.length . filter isVisible where isVisible c = ord c `notElem` ([5, 6, 7] ++ [16 .. 31]) -- Basic pretty printing algorithm: -- -- 1. Determine for each group in the document its width, i.e. the space it -- requires for printing if it was printed horizontally, all in one line. -- 2. Traverse document tree and keep track of remaining free space in current -- output line. -- At the start of a group compare remaining space with width of the group: -- If the width is smaller or equal, the group is formatted horizontally, -- otherwise vertically. -- Determine widths of all groups and produce actual layout by traversing token -- sequence a single time using continuations: -- At the start of each group construct a `group output function` which receives -- formate information and information about the remaining space at the -- beginning of the group. -- Since groups can be nested we don't want to update a width value for each -- surrounding group when processing a token. Instead we introduce an absolute -- measure of a token's position: The width of a group is the difference between -- the position of its `CloseGroup` token and the position of its `OpenGroup` token. -- When traversing the document only the `group output function` of the -- innermost group is extended. All the other `group output function`s are -- passed on unchanged. When we come across a `CloseGroup` token we merge the -- function for the innermost group with the function for the next inner group. -- noGroup is used when there is currently no deferred group noGroup :: Tokens -> Width -> Position -> Out noGroup EOD _ _ _ _ _ = "" -- should not occur: noGroup (Empty ts) w p r ms fs = noGroup ts w p r ms fs noGroup (Text t ts) w p r ms fs = t ++ noGroup ts w (p + l) (r - l) ms fs where l = length t noGroup (LineBreak _ ts) w p _ ms fs = case ms of [] -> error "Pretty.noGroup: illegal line" m:_ -> '\n' : addSpaces m ts ++ noGroup ts w (p + 1) (w - m) ms fs noGroup (OpenGroup ts) w p r ms fs = oneGroup ts w p (p + r) (\_ c -> c) r ms fs noGroup (CloseGroup ts) w p r ms fs = noGroup ts w p r ms fs -- may have been pruned noGroup (OpenNest n ts) w p r ms fs = noGroup ts w p r (applyNesting n w r ms) fs noGroup (CloseNest ts) w p r ms fs = noGroup ts w p r (unApplyNesting ms) fs noGroup (OpenFormat f ts) w p r ms fs = applyFormat f ++ noGroup ts w p r ms (f:fs) noGroup (CloseFormat ts) w p r ms fs = applyFormat f ++ noGroup ts w p r ms ofs where (f, ofs) = resetFormat fs -- oneGroup is used when there is one deferred group -- Whenever the tokens `Text` or `LineBreak` are processed, -- i.e. the current position is increased, -- pruneOne checks whether whether the group still fits the line -- Furthermore the `group output function` is extended with the current token oneGroup :: Tokens -> Width -> Position -> EndPosition -> OutGroupPrefix -> Out oneGroup EOD _ _ _ _ = error "Pretty.oneGroup: EOD" -- should not occur: oneGroup (Empty ts) w p e outGrpPre = oneGroup ts w p e outGrpPre oneGroup (Text s ts) w p e outGrpPre = pruneOne ts w (p + l) e (\h cont -> outGrpPre h (outText cont)) where l = length s outText cont r ms fs = s ++ cont (r - l) ms fs oneGroup (LineBreak Nothing ts) w p _ outGrpPre = outGrpPre False (outLine (noGroup ts w p)) where outLine _ _ [] _ = error "Pretty.oneGroup.outLine: empty margins" outLine cont _ ms@(m:_) fs = '\n' : addSpaces m ts ++ cont (w - m) ms fs oneGroup (LineBreak (Just s) ts) w p e outGrpPre = pruneOne ts w (p + l) e (\h cont -> outGrpPre h (outLine h cont)) where l = length s outLine _ _ _ [] _ = error "Pretty.oneGroup.outLine: empty margins" outLine h cont r ms@(m:_) fs = if h then s ++ cont (r - l) ms fs else '\n' : addSpaces m ts ++ cont (w - m) ms fs oneGroup (OpenGroup ts) w p e outGrpPre = multiGroup ts w p e outGrpPre Q.empty p (\_ cont -> cont) oneGroup (CloseGroup ts) w p e outGrpPre = outGrpPre (p <= e) (noGroup ts w p) oneGroup (OpenNest n ts) w p e outGrpPre = oneGroup ts w p e (\h cont -> outGrpPre h (\r ms fs -> cont r (applyNesting n w r ms) fs)) oneGroup (CloseNest ts) w p e outGrpPre = oneGroup ts w p e (\h cont -> outGrpPre h (\r ms fs -> cont r (unApplyNesting ms) fs)) oneGroup (OpenFormat f ts) w p e outGrpPre = oneGroup ts w p e (\h cont -> outGrpPre h (outFormat cont)) where outFormat cont r ms fs = applyFormat f ++ cont r ms (f:fs) oneGroup (CloseFormat ts) w p e outGrpPre = oneGroup ts w p e (\h cont -> outGrpPre h (outUnformat cont)) where outUnformat cont r ms fs = applyFormat f ++ cont r ms ofs where (f, ofs) = resetFormat fs -- multiGroup is used when there are at least two deferred groups -- Whenever the tokens `Text` or `LineBreak` are processed, i.e. the current position -- is increased, pruneMulti checks whether whether the outermost group still -- fits the line. -- Furthermore the `group output function` of the innermost group is extended -- with the current token. -- When we come across a `OpenGroup` token during traversal of the token sequence, -- the current innermost `group output function` is added to the queue. -- Reaching a `CloseGroup` token it is checked whether the queue still contains a -- deferred `group output function`: If the queue is empty, there is only one -- group left, otherwise there are at least two groups left. -- In both cases the function for the innermost group is merged with the -- function for the next inner group multiGroup :: Tokens -> Width -> Position -> EndPosition -> OutGroupPrefix -> Q.Queue (StartPosition, OutGroupPrefix) -> StartPosition -> OutGroupPrefix -> Out multiGroup EOD _ _ _ _ _ _ _ = error "Pretty.multiGroup: EOD" -- should not occur: multiGroup (Empty ts) w p e outGrpPreOuter qs s outGrpPreInner = multiGroup ts w p e outGrpPreOuter qs s outGrpPreInner multiGroup (Text t ts) w p e outGrpPreOuter qs s outGrpPreInner = pruneMulti ts w (p+l) e outGrpPreOuter qs s (\h cont -> outGrpPreInner h (outText cont)) where l = length t outText cont r ms fs = t ++ cont (r-l) ms fs multiGroup (LineBreak Nothing ts) w p _ outGrpPreOuter qs _ outGrpPreInner = pruneAll outGrpPreOuter qs where pruneAll outGrpPreOuter' qs' = outGrpPreOuter' False (\r -> (case Q.matchLast qs' of Nothing -> outGrpPreInner False (outLine (noGroup ts w p)) Just ((_,outGrpPre),qss) -> pruneAll outGrpPre qss) r) outLine _ _ [] _ = error "Pretty.oneGroup.outLine: empty margins" outLine cont _ ms@(m:_) fs = '\n' : addSpaces m ts ++ cont (w - m) ms fs multiGroup (LineBreak (Just s) ts) w p e outGrpPreOuter qs si outGrpPreInner = pruneMulti ts w (p + l) e outGrpPreOuter qs si (\h cont -> outGrpPreInner h (outLine h cont)) where l = length s outLine _ _ _ [] _ = error "Pretty.multiGroup.outLine: empty margins" outLine h cont r ms@(m:_) fs = if h then s ++ cont (r-l) ms fs else '\n': addSpaces m ts ++ cont (w-m) ms fs multiGroup (OpenGroup ts) w p e outGrpPreOuter qs si outGrpPreInner = multiGroup ts w p e outGrpPreOuter (Q.cons (si,outGrpPreInner) qs) p (\_ cont -> cont) multiGroup (CloseGroup ts) w p e outGrpPreOuter qs si outGrpPreInner = case Q.matchHead qs of Nothing -> oneGroup ts w p e (\h cont -> outGrpPreOuter h (\ri -> outGrpPreInner (p<=si+ri) cont ri)) Just ((s,outGrpPre),qs') -> multiGroup ts w p e outGrpPreOuter qs' s (\h cont -> outGrpPre h (\ri -> outGrpPreInner (p<=si+ri) cont ri)) multiGroup (OpenNest n ts) w p e outGrpPreOuter qs si outGrpPreInner = multiGroup ts w p e outGrpPreOuter qs si (\h cont -> outGrpPreInner h (\r ms fs -> cont r (applyNesting n w r ms) fs)) multiGroup (CloseNest ts) w p e outGrpPreOuter qs si outGrpPreInner = multiGroup ts w p e outGrpPreOuter qs si (\h cont -> outGrpPreInner h (\r ms fs -> cont r (unApplyNesting ms) fs)) multiGroup (OpenFormat f ts) w p e outGrpPreOuter qs si outGrpPreInner = multiGroup ts w p e outGrpPreOuter qs si (\h cont -> outGrpPreInner h (outFormat cont)) where outFormat cont r ms fs = applyFormat f ++ cont r ms (f:fs) multiGroup (CloseFormat ts) w p e outGrpPreOuter qs si outGrpPreInner = multiGroup ts w p e outGrpPreOuter qs si (\h cont -> outGrpPreInner h (outUnformat cont)) where outUnformat cont r ms fs = applyFormat f ++ cont r ms ofs where (f, ofs) = resetFormat fs -- pruneOne checks whether the outermost group (in this case there is only one -- group) still fits in the current line. If it doesn't fit, it applies the -- corresponding `group output function` (the group is formatted vertically) -- and continues processing the token sequence pruneOne :: Tokens -> Width -> Position -> EndPosition -> OutGroupPrefix -> Out pruneOne ts w p e outGrpPre | p <= e = oneGroup ts w p e outGrpPre | otherwise = outGrpPre False (noGroup ts w p) -- pruneMulti checks whether the outermost group (in this case there are at -- least two groups) still fits in the current line. If it doesn't fit, it -- applies the corresponding `group output function` (the last queue entry) and -- continues checking whether the next outermost group fits pruneMulti :: Tokens -> Width -> Position -> EndPosition -> OutGroupPrefix -> Q.Queue (StartPosition, OutGroupPrefix) -> StartPosition -> OutGroupPrefix -> Out pruneMulti ts w p e outGrpPreOuter qs si outGrpPreInner | p <= e = multiGroup ts w p e outGrpPreOuter qs si outGrpPreInner | otherwise = outGrpPreOuter False (\r -> (case Q.matchLast qs of Nothing -> pruneOne ts w p (si+r) outGrpPreInner Just ((s,outGrpPre),qs') -> pruneMulti ts w p (s+r) outGrpPre qs' si outGrpPreInner) r) -------------------------------------------------------------------------------- -- Debugging -------------------------------------------------------------------------------- -- inspect the token sequence of a document inspect :: Doc -> Tokens inspect (Doc d) = normalise (d EOD) |