src/jexer/teditor/Line.java

   1 /*
   2  * Jexer - Java Text User Interface
   3  *
   4  * The MIT License (MIT)
   5  *
   6  * Copyright (C) 2019 Kevin Lamonte
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included in
  16  * all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  21  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  24  * DEALINGS IN THE SOFTWARE.
  25  *
  26  * @author Kevin Lamonte [kevin.lamonte@gmail.com]
  27  * @version 1
  28  */
  29 package jexer.teditor;
  30
  31 import java.util.ArrayList;
  32 import java.util.List;
  33
  34 import jexer.bits.CellAttributes;
  35 import jexer.bits.GraphicsChars;
  36 import jexer.bits.StringUtils;
  37
  38 /**
  39  * A Line represents a single line of text on the screen, as a collection of
  40  * words.
  41  */
  42 public class Line {
  43
  44     // ------------------------------------------------------------------------
  45     // Variables --------------------------------------------------------------
  46     // ------------------------------------------------------------------------
  47
  48     /**
  49      * The list of words.
  50      */
  51     private ArrayList<Word> words = new ArrayList<Word>();
  52
  53     /**
  54      * The default color for the TEditor class.
  55      */
  56     private CellAttributes defaultColor = null;
  57
  58     /**
  59      * The text highlighter to use.
  60      */
  61     private Highlighter highlighter = null;
  62
  63     /**
  64      * The current edition position on this line.
  65      */
  66     private int position = 0;
  67
  68     /**
  69      * The current editing position screen column number.
  70      */
  71     private int screenPosition = 0;
  72
  73     /**
  74      * The raw text of this line, what is passed to Word to determine
  75      * highlighting behavior.
  76      */
  77     private StringBuilder rawText;
  78
  79     // ------------------------------------------------------------------------
  80     // Constructors -----------------------------------------------------------
  81     // ------------------------------------------------------------------------
  82
  83     /**
  84      * Construct a new Line from an existing text string, and highlight
  85      * certain strings.
  86      *
  87      * @param str the text string
  88      * @param defaultColor the color for unhighlighted text
  89      * @param highlighter the highlighter to use
  90      */
  91     public Line(final String str, final CellAttributes defaultColor,
  92         final Highlighter highlighter) {
  93
  94         this.defaultColor = defaultColor;
  95         this.highlighter = highlighter;
  96
  97         this.rawText = new StringBuilder();
  98         int col = 0;
  99         for (int i = 0; i < str.length(); i++) {
 100             char ch = str.charAt(i);
 101             if (ch == '\t') {
 102                 // Expand tabs
 103                 int j = col % 8;
 104                 do {
 105                     rawText.append(' ');
 106                     j++;
 107                     col++;
 108                 } while ((j % 8) != 0);
 109                 continue;
 110             }
 111             if ((ch <= 0x20) || (ch == 0x7F)) {
 112                 // Replace all other C0 bytes with CP437 glyphs.
 113                 rawText.append(GraphicsChars.CP437[(int) ch]);
 114                 col++;
 115                 continue;
 116             }
 117
 118             rawText.append(ch);
 119             col++;
 120         }
 121
 122         scanLine();
 123     }
 124
 125     /**
 126      * Construct a new Line from an existing text string.
 127      *
 128      * @param str the text string
 129      * @param defaultColor the color for unhighlighted text
 130      */
 131     public Line(final String str, final CellAttributes defaultColor) {
 132         this(str, defaultColor, null);
 133     }
 134
 135     /**
 136      * Private constructor used by dup().
 137      */
 138     private Line() {
 139         // NOP
 140     }
 141
 142     // ------------------------------------------------------------------------
 143     // Line -------------------------------------------------------------------
 144     // ------------------------------------------------------------------------
 145
 146     /**
 147      * Create a duplicate instance.
 148      *
 149      * @return duplicate intance
 150      */
 151     public Line dup() {
 152         Line other = new Line();
 153         other.defaultColor = defaultColor;
 154         other.highlighter = highlighter;
 155         other.position = position;
 156         other.screenPosition = screenPosition;
 157         other.rawText = new StringBuilder(rawText);
 158         other.scanLine();
 159         return other;
 160     }
 161
 162     /**
 163      * Get a (shallow) copy of the words in this line.
 164      *
 165      * @return a copy of the word list
 166      */
 167     public List<Word> getWords() {
 168         return new ArrayList<Word>(words);
 169     }
 170
 171     /**
 172      * Get the current cursor position in the text.
 173      *
 174      * @return the cursor position
 175      */
 176     public int getRawCursor() {
 177         return position;
 178     }
 179
 180     /**
 181      * Get the current cursor position on screen.
 182      *
 183      * @return the cursor position
 184      */
 185     public int getCursor() {
 186         return screenPosition;
 187     }
 188
 189     /**
 190      * Set the current cursor position.
 191      *
 192      * @param cursor the new cursor position
 193      */
 194     public void setCursor(final int cursor) {
 195         if ((cursor < 0)
 196             || ((cursor >= getDisplayLength())
 197                 && (getDisplayLength() > 0))
 198         ) {
 199             throw new IndexOutOfBoundsException("Max length is " +
 200                 getDisplayLength() + ", requested position " + cursor);
 201         }
 202         screenPosition = cursor;
 203         position = screenToTextPosition(screenPosition);
 204     }
 205
 206     /**
 207      * Get the character at the current cursor position in the text.
 208      *
 209      * @return the character, or -1 if the cursor is at the end of the line
 210      */
 211     public int getChar() {
 212         if (position == rawText.length()) {
 213             return -1;
 214         }
 215         return rawText.codePointAt(position);
 216     }
 217
 218     /**
 219      * Get the on-screen display length.
 220      *
 221      * @return the number of cells needed to display this line
 222      */
 223     public int getDisplayLength() {
 224         int n = StringUtils.width(rawText.toString());
 225
 226         if (n > 0) {
 227             // If we have any visible characters, add one to the display so
 228             // that the position is immediately after the data.
 229             return n + 1;
 230         }
 231         return n;
 232     }
 233
 234     /**
 235      * Get the raw string that matches this line.
 236      *
 237      * @return the string
 238      */
 239     public String getRawString() {
 240         return rawText.toString();
 241     }
 242
 243     /**
 244      * Get the raw length of this line.
 245      *
 246      * @return the length of this line in characters, which may be different
 247      * from the number of cells needed to display it
 248      */
 249     public int length() {
 250         return rawText.length();
 251     }
 252
 253     /**
 254      * Scan rawText and make words out of it.  Note package private access.
 255      */
 256     void scanLine() {
 257         words.clear();
 258         Word word = new Word(this.defaultColor, this.highlighter);
 259         words.add(word);
 260         for (int i = 0; i < rawText.length();) {
 261             int ch = rawText.codePointAt(i);
 262             i += Character.charCount(ch);
 263             Word newWord = word.addChar(ch);
 264             if (newWord != word) {
 265                 words.add(newWord);
 266                 word = newWord;
 267             }
 268         }
 269         for (Word w: words) {
 270             w.applyHighlight();
 271         }
 272     }
 273
 274     /**
 275      * Decrement the cursor by one.  If at the first column, do nothing.
 276      *
 277      * @return true if the cursor position changed
 278      */
 279     public boolean left() {
 280         if (position == 0) {
 281             return false;
 282         }
 283         screenPosition -= StringUtils.width(rawText.codePointBefore(position));
 284         position -= Character.charCount(rawText.codePointBefore(position));
 285         return true;
 286     }
 287
 288     /**
 289      * Increment the cursor by one.  If at the last column, do nothing.
 290      *
 291      * @return true if the cursor position changed
 292      */
 293     public boolean right() {
 294         if (getDisplayLength() == 0) {
 295             return false;
 296         }
 297         if (screenPosition == getDisplayLength() - 1) {
 298             return false;
 299         }
 300         if (position < rawText.length()) {
 301             screenPosition += StringUtils.width(rawText.codePointAt(position));
 302             position += Character.charCount(rawText.codePointAt(position));
 303         }
 304         assert (position <= rawText.length());
 305         return true;
 306     }
 307
 308     /**
 309      * Go to the first column of this line.
 310      *
 311      * @return true if the cursor position changed
 312      */
 313     public boolean home() {
 314         if (position > 0) {
 315             position = 0;
 316             screenPosition = 0;
 317             return true;
 318         }
 319         return false;
 320     }
 321
 322     /**
 323      * Go to the last column of this line.
 324      *
 325      * @return true if the cursor position changed
 326      */
 327     public boolean end() {
 328         if (screenPosition != getDisplayLength() - 1) {
 329             position = rawText.length();
 330             screenPosition = StringUtils.width(rawText.toString());
 331             return true;
 332         }
 333         return false;
 334     }
 335
 336     /**
 337      * Delete the character under the cursor.
 338      */
 339     public void del() {
 340         assert (words.size() > 0);
 341
 342         if (screenPosition < getDisplayLength()) {
 343             int n = Character.charCount(rawText.codePointAt(position));
 344             for (int i = 0; i < n; i++) {
 345                 rawText.deleteCharAt(position);
 346             }
 347         }
 348
 349         // Re-scan the line to determine the new word boundaries.
 350         scanLine();
 351     }
 352
 353     /**
 354      * Delete the character immediately preceeding the cursor.
 355      *
 356      * @param tabSize the tab stop size
 357      * @param backspaceUnindents If true, backspace at an indent level goes
 358      * back a full indent level.  If false, backspace always goes back one
 359      * column.
 360      */
 361     public void backspace(final int tabSize, final boolean backspaceUnindents) {
 362         if ((backspaceUnindents == true)
 363             && (tabSize > 0)
 364             && (screenPosition > 0)
 365             && (rawText.charAt(position - 1) == ' ')
 366             && ((screenPosition % tabSize) == 0)
 367         ) {
 368             boolean doBackTab = true;
 369             for (int i = 0; i < position; i++) {
 370                 if (rawText.charAt(i) != ' ') {
 371                     doBackTab = false;
 372                     break;
 373                 }
 374             }
 375             if (doBackTab) {
 376                 backTab(tabSize);
 377                 return;
 378             }
 379         }
 380
 381         if (left()) {
 382             del();
 383         }
 384     }
 385
 386     /**
 387      * Insert a character at the cursor.
 388      *
 389      * @param ch the character to insert
 390      */
 391     public void addChar(final int ch) {
 392         if (screenPosition < getDisplayLength() - 1) {
 393             rawText.insert(position, Character.toChars(ch));
 394         } else {
 395             rawText.append(Character.toChars(ch));
 396         }
 397         position += Character.charCount(ch);
 398         screenPosition += StringUtils.width(ch);
 399         scanLine();
 400     }
 401
 402     /**
 403      * Replace a character at the cursor.
 404      *
 405      * @param ch the character to replace
 406      */
 407     public void replaceChar(final int ch) {
 408         if (screenPosition < getDisplayLength() - 1) {
 409             // Replace character
 410             String oldText = rawText.toString();
 411             rawText = new StringBuilder(oldText.substring(0, position));
 412             rawText.append(Character.toChars(ch));
 413             rawText.append(oldText.substring(position + 1));
 414             screenPosition += StringUtils.width(rawText.codePointAt(position));
 415             position += Character.charCount(ch);
 416         } else {
 417             rawText.append(Character.toChars(ch));
 418             position += Character.charCount(ch);
 419             screenPosition += StringUtils.width(ch);
 420         }
 421         scanLine();
 422     }
 423
 424     /**
 425      * Determine string position from screen position.
 426      *
 427      * @param screenPosition the position on screen
 428      * @return the equivalent position in text
 429      */
 430     private int screenToTextPosition(final int screenPosition) {
 431         if (screenPosition == 0) {
 432             return 0;
 433         }
 434
 435         int n = 0;
 436         for (int i = 0; i < rawText.length(); i++) {
 437             n += StringUtils.width(rawText.codePointAt(i));
 438             if (n >= screenPosition) {
 439                 return i + 1;
 440             }
 441         }
 442         // screenPosition exceeds the available text length.
 443         throw new IndexOutOfBoundsException("screenPosition " + screenPosition +
 444             " exceeds available text length " + rawText.length());
 445     }
 446
 447     /**
 448      * Trim trailing whitespace from line, repositioning cursor if needed.
 449      */
 450     public void trimRight() {
 451         if (rawText.length() == 0) {
 452             return;
 453         }
 454         if (!Character.isWhitespace(rawText.charAt(rawText.length() - 1))) {
 455             return;
 456         }
 457         while ((rawText.length() > 0)
 458             && Character.isWhitespace(rawText.charAt(rawText.length() - 1))
 459         ) {
 460             rawText.deleteCharAt(rawText.length() - 1);
 461         }
 462         if (position >= rawText.length()) {
 463             end();
 464         }
 465         scanLine();
 466     }
 467
 468     /**
 469      * Handle the tab character.
 470      *
 471      * @param tabSize the tab stop size
 472      */
 473     public void tab(final int tabSize) {
 474         if (tabSize > 0) {
 475             do {
 476                 addChar(' ');
 477             } while ((screenPosition % tabSize) != 0);
 478         }
 479     }
 480
 481     /**
 482      * Handle the backtab (shift-tab) character.
 483      *
 484      * @param tabSize the tab stop size
 485      */
 486     public void backTab(final int tabSize) {
 487         if ((tabSize > 0) && (screenPosition > 0)
 488             && (rawText.charAt(position - 1) == ' ')
 489         ) {
 490             do {
 491                 backspace(tabSize, false);
 492             } while (((screenPosition % tabSize) != 0)
 493                 && (screenPosition > 0)
 494                 && (rawText.charAt(position - 1) == ' '));
 495         }
 496     }
 497
 498 }