scintilla/src/PositionCache.cxx

   1 // Scintilla source code edit control
   2 /** @file PositionCache.cxx
   3  ** Classes for caching layout information.
   4  **/
   5 // Copyright 1998-2007 by Neil Hodgson <neilh@scintilla.org>
   6 // The License.txt file describes the conditions under which this software may be distributed.
   7
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <stdio.h>
  11 #include <ctype.h>
  12
  13 #include <stdexcept>
  14 #include <string>
  15 #include <vector>
  16 #include <map>
  17 #include <algorithm>
  18
  19 #include "Platform.h"
  20
  21 #include "ILexer.h"
  22 #include "Scintilla.h"
  23
  24 #include "Position.h"
  25 #include "SplitVector.h"
  26 #include "Partitioning.h"
  27 #include "RunStyles.h"
  28 #include "ContractionState.h"
  29 #include "CellBuffer.h"
  30 #include "KeyMap.h"
  31 #include "Indicator.h"
  32 #include "XPM.h"
  33 #include "LineMarker.h"
  34 #include "Style.h"
  35 #include "ViewStyle.h"
  36 #include "CharClassify.h"
  37 #include "Decoration.h"
  38 #include "CaseFolder.h"
  39 #include "Document.h"
  40 #include "UniConversion.h"
  41 #include "Selection.h"
  42 #include "PositionCache.h"
  43
  44 #ifdef SCI_NAMESPACE
  45 using namespace Scintilla;
  46 #endif
  47
  48 LineLayout::LineLayout(int maxLineLength_) :
  49         lineStarts(0),
  50         lenLineStarts(0),
  51         lineNumber(-1),
  52         inCache(false),
  53         maxLineLength(-1),
  54         numCharsInLine(0),
  55         numCharsBeforeEOL(0),
  56         validity(llInvalid),
  57         xHighlightGuide(0),
  58         highlightColumn(0),
  59         containsCaret(false),
  60         edgeColumn(0),
  61         chars(0),
  62         styles(0),
  63         positions(0),
  64         hotspot(0,0),
  65         widthLine(wrapWidthInfinite),
  66         lines(1),
  67         wrapIndent(0) {
  68         bracePreviousStyles[0] = 0;
  69         bracePreviousStyles[1] = 0;
  70         Resize(maxLineLength_);
  71 }
  72
  73 LineLayout::~LineLayout() {
  74         Free();
  75 }
  76
  77 void LineLayout::Resize(int maxLineLength_) {
  78         if (maxLineLength_ > maxLineLength) {
  79                 Free();
  80                 chars = new char[maxLineLength_ + 1];
  81                 styles = new unsigned char[maxLineLength_ + 1];
  82                 // Extra position allocated as sometimes the Windows
  83                 // GetTextExtentExPoint API writes an extra element.
  84                 positions = new XYPOSITION[maxLineLength_ + 1 + 1];
  85                 maxLineLength = maxLineLength_;
  86         }
  87 }
  88
  89 void LineLayout::Free() {
  90         delete []chars;
  91         chars = 0;
  92         delete []styles;
  93         styles = 0;
  94         delete []positions;
  95         positions = 0;
  96         delete []lineStarts;
  97         lineStarts = 0;
  98 }
  99
 100 void LineLayout::Invalidate(validLevel validity_) {
 101         if (validity > validity_)
 102                 validity = validity_;
 103 }
 104
 105 int LineLayout::LineStart(int line) const {
 106         if (line <= 0) {
 107                 return 0;
 108         } else if ((line >= lines) || !lineStarts) {
 109                 return numCharsInLine;
 110         } else {
 111                 return lineStarts[line];
 112         }
 113 }
 114
 115 int LineLayout::LineLastVisible(int line) const {
 116         if (line < 0) {
 117                 return 0;
 118         } else if ((line >= lines-1) || !lineStarts) {
 119                 return numCharsBeforeEOL;
 120         } else {
 121                 return lineStarts[line+1];
 122         }
 123 }
 124
 125 Range LineLayout::SubLineRange(int subLine) const {
 126         return Range(LineStart(subLine), LineLastVisible(subLine));
 127 }
 128
 129 bool LineLayout::InLine(int offset, int line) const {
 130         return ((offset >= LineStart(line)) && (offset < LineStart(line + 1))) ||
 131                 ((offset == numCharsInLine) && (line == (lines-1)));
 132 }
 133
 134 void LineLayout::SetLineStart(int line, int start) {
 135         if ((line >= lenLineStarts) && (line != 0)) {
 136                 int newMaxLines = line + 20;
 137                 int *newLineStarts = new int[newMaxLines];
 138                 for (int i = 0; i < newMaxLines; i++) {
 139                         if (i < lenLineStarts)
 140                                 newLineStarts[i] = lineStarts[i];
 141                         else
 142                                 newLineStarts[i] = 0;
 143                 }
 144                 delete []lineStarts;
 145                 lineStarts = newLineStarts;
 146                 lenLineStarts = newMaxLines;
 147         }
 148         lineStarts[line] = start;
 149 }
 150
 151 void LineLayout::SetBracesHighlight(Range rangeLine, const Position braces[],
 152                                     char bracesMatchStyle, int xHighlight, bool ignoreStyle) {
 153         if (!ignoreStyle && rangeLine.ContainsCharacter(braces[0])) {
 154                 int braceOffset = braces[0] - rangeLine.start;
 155                 if (braceOffset < numCharsInLine) {
 156                         bracePreviousStyles[0] = styles[braceOffset];
 157                         styles[braceOffset] = bracesMatchStyle;
 158                 }
 159         }
 160         if (!ignoreStyle && rangeLine.ContainsCharacter(braces[1])) {
 161                 int braceOffset = braces[1] - rangeLine.start;
 162                 if (braceOffset < numCharsInLine) {
 163                         bracePreviousStyles[1] = styles[braceOffset];
 164                         styles[braceOffset] = bracesMatchStyle;
 165                 }
 166         }
 167         if ((braces[0] >= rangeLine.start && braces[1] <= rangeLine.end) ||
 168                 (braces[1] >= rangeLine.start && braces[0] <= rangeLine.end)) {
 169                 xHighlightGuide = xHighlight;
 170         }
 171 }
 172
 173 void LineLayout::RestoreBracesHighlight(Range rangeLine, const Position braces[], bool ignoreStyle) {
 174         if (!ignoreStyle && rangeLine.ContainsCharacter(braces[0])) {
 175                 int braceOffset = braces[0] - rangeLine.start;
 176                 if (braceOffset < numCharsInLine) {
 177                         styles[braceOffset] = bracePreviousStyles[0];
 178                 }
 179         }
 180         if (!ignoreStyle && rangeLine.ContainsCharacter(braces[1])) {
 181                 int braceOffset = braces[1] - rangeLine.start;
 182                 if (braceOffset < numCharsInLine) {
 183                         styles[braceOffset] = bracePreviousStyles[1];
 184                 }
 185         }
 186         xHighlightGuide = 0;
 187 }
 188
 189 int LineLayout::FindBefore(XYPOSITION x, int lower, int upper) const {
 190         do {
 191                 int middle = (upper + lower + 1) / 2;   // Round high
 192                 XYPOSITION posMiddle = positions[middle];
 193                 if (x < posMiddle) {
 194                         upper = middle - 1;
 195                 } else {
 196                         lower = middle;
 197                 }
 198         } while (lower < upper);
 199         return lower;
 200 }
 201
 202
 203 int LineLayout::FindPositionFromX(XYPOSITION x, Range range, bool charPosition) const {
 204         int pos = FindBefore(x, range.start, range.end);
 205         while (pos < range.end) {
 206                 if (charPosition) {
 207                         if (x < (positions[pos + 1])) {
 208                                 return pos;
 209                         }
 210                 } else {
 211                         if (x < ((positions[pos] + positions[pos + 1]) / 2)) {
 212                                 return pos;
 213                         }
 214                 }
 215                 pos++;
 216         }
 217         return range.end;
 218 }
 219
 220 Point LineLayout::PointFromPosition(int posInLine, int lineHeight) const {
 221         Point pt;
 222         // In case of very long line put x at arbitrary large position
 223         if (posInLine > maxLineLength) {
 224                 pt.x = positions[maxLineLength] - positions[LineStart(lines)];
 225         }
 226
 227         for (int subLine = 0; subLine < lines; subLine++) {
 228                 const Range rangeSubLine = SubLineRange(subLine);
 229                 if (posInLine >= rangeSubLine.start) {
 230                         pt.y = static_cast<XYPOSITION>(subLine*lineHeight);
 231                         if (posInLine <= rangeSubLine.end) {
 232                                 pt.x = positions[posInLine] - positions[rangeSubLine.start];
 233                                 if (rangeSubLine.start != 0)    // Wrapped lines may be indented
 234                                         pt.x += wrapIndent;
 235                         }
 236                 } else {
 237                         break;
 238                 }
 239         }
 240         return pt;
 241 }
 242
 243 int LineLayout::EndLineStyle() const {
 244         return styles[numCharsBeforeEOL > 0 ? numCharsBeforeEOL-1 : 0];
 245 }
 246
 247 LineLayoutCache::LineLayoutCache() :
 248         level(0),
 249         allInvalidated(false), styleClock(-1), useCount(0) {
 250         Allocate(0);
 251 }
 252
 253 LineLayoutCache::~LineLayoutCache() {
 254         Deallocate();
 255 }
 256
 257 void LineLayoutCache::Allocate(size_t length_) {
 258         PLATFORM_ASSERT(cache.empty());
 259         allInvalidated = false;
 260         cache.resize(length_);
 261 }
 262
 263 void LineLayoutCache::AllocateForLevel(int linesOnScreen, int linesInDoc) {
 264         PLATFORM_ASSERT(useCount == 0);
 265         size_t lengthForLevel = 0;
 266         if (level == llcCaret) {
 267                 lengthForLevel = 1;
 268         } else if (level == llcPage) {
 269                 lengthForLevel = linesOnScreen + 1;
 270         } else if (level == llcDocument) {
 271                 lengthForLevel = linesInDoc;
 272         }
 273         if (lengthForLevel > cache.size()) {
 274                 Deallocate();
 275                 Allocate(lengthForLevel);
 276         } else {
 277                 if (lengthForLevel < cache.size()) {
 278                         for (size_t i = lengthForLevel; i < cache.size(); i++) {
 279                                 delete cache[i];
 280                                 cache[i] = 0;
 281                         }
 282                 }
 283                 cache.resize(lengthForLevel);
 284         }
 285         PLATFORM_ASSERT(cache.size() == lengthForLevel);
 286 }
 287
 288 void LineLayoutCache::Deallocate() {
 289         PLATFORM_ASSERT(useCount == 0);
 290         for (size_t i = 0; i < cache.size(); i++)
 291                 delete cache[i];
 292         cache.clear();
 293 }
 294
 295 void LineLayoutCache::Invalidate(LineLayout::validLevel validity_) {
 296         if (!cache.empty() && !allInvalidated) {
 297                 for (size_t i = 0; i < cache.size(); i++) {
 298                         if (cache[i]) {
 299                                 cache[i]->Invalidate(validity_);
 300                         }
 301                 }
 302                 if (validity_ == LineLayout::llInvalid) {
 303                         allInvalidated = true;
 304                 }
 305         }
 306 }
 307
 308 void LineLayoutCache::SetLevel(int level_) {
 309         allInvalidated = false;
 310         if ((level_ != -1) && (level != level_)) {
 311                 level = level_;
 312                 Deallocate();
 313         }
 314 }
 315
 316 LineLayout *LineLayoutCache::Retrieve(int lineNumber, int lineCaret, int maxChars, int styleClock_,
 317                                       int linesOnScreen, int linesInDoc) {
 318         AllocateForLevel(linesOnScreen, linesInDoc);
 319         if (styleClock != styleClock_) {
 320                 Invalidate(LineLayout::llCheckTextAndStyle);
 321                 styleClock = styleClock_;
 322         }
 323         allInvalidated = false;
 324         int pos = -1;
 325         LineLayout *ret = 0;
 326         if (level == llcCaret) {
 327                 pos = 0;
 328         } else if (level == llcPage) {
 329                 if (lineNumber == lineCaret) {
 330                         pos = 0;
 331                 } else if (cache.size() > 1) {
 332                         pos = 1 + (lineNumber % (cache.size() - 1));
 333                 }
 334         } else if (level == llcDocument) {
 335                 pos = lineNumber;
 336         }
 337         if (pos >= 0) {
 338                 PLATFORM_ASSERT(useCount == 0);
 339                 if (!cache.empty() && (pos < static_cast<int>(cache.size()))) {
 340                         if (cache[pos]) {
 341                                 if ((cache[pos]->lineNumber != lineNumber) ||
 342                                         (cache[pos]->maxLineLength < maxChars)) {
 343                                         delete cache[pos];
 344                                         cache[pos] = 0;
 345                                 }
 346                         }
 347                         if (!cache[pos]) {
 348                                 cache[pos] = new LineLayout(maxChars);
 349                         }
 350                         cache[pos]->lineNumber = lineNumber;
 351                         cache[pos]->inCache = true;
 352                         ret = cache[pos];
 353                         useCount++;
 354                 }
 355         }
 356
 357         if (!ret) {
 358                 ret = new LineLayout(maxChars);
 359                 ret->lineNumber = lineNumber;
 360         }
 361
 362         return ret;
 363 }
 364
 365 void LineLayoutCache::Dispose(LineLayout *ll) {
 366         allInvalidated = false;
 367         if (ll) {
 368                 if (!ll->inCache) {
 369                         delete ll;
 370                 } else {
 371                         useCount--;
 372                 }
 373         }
 374 }
 375
 376 // Simply pack the (maximum 4) character bytes into an int
 377 static inline int KeyFromString(const char *charBytes, size_t len) {
 378         PLATFORM_ASSERT(len <= 4);
 379         int k=0;
 380         for (size_t i=0; i<len && charBytes[i]; i++) {
 381                 k = k * 0x100;
 382                 k += static_cast<unsigned char>(charBytes[i]);
 383         }
 384         return k;
 385 }
 386
 387 SpecialRepresentations::SpecialRepresentations() {
 388         std::fill(startByteHasReprs, startByteHasReprs+0x100, 0);
 389 }
 390
 391 void SpecialRepresentations::SetRepresentation(const char *charBytes, const char *value) {
 392         MapRepresentation::iterator it = mapReprs.find(KeyFromString(charBytes, UTF8MaxBytes));
 393         if (it == mapReprs.end()) {
 394                 // New entry so increment for first byte
 395                 startByteHasReprs[static_cast<unsigned char>(charBytes[0])]++;
 396         }
 397         mapReprs[KeyFromString(charBytes, UTF8MaxBytes)] = Representation(value);
 398 }
 399
 400 void SpecialRepresentations::ClearRepresentation(const char *charBytes) {
 401         MapRepresentation::iterator it = mapReprs.find(KeyFromString(charBytes, UTF8MaxBytes));
 402         if (it != mapReprs.end()) {
 403                 mapReprs.erase(it);
 404                 startByteHasReprs[static_cast<unsigned char>(charBytes[0])]--;
 405         }
 406 }
 407
 408 const Representation *SpecialRepresentations::RepresentationFromCharacter(const char *charBytes, size_t len) const {
 409         PLATFORM_ASSERT(len <= 4);
 410         if (!startByteHasReprs[static_cast<unsigned char>(charBytes[0])])
 411                 return 0;
 412         MapRepresentation::const_iterator it = mapReprs.find(KeyFromString(charBytes, len));
 413         if (it != mapReprs.end()) {
 414                 return &(it->second);
 415         }
 416         return 0;
 417 }
 418
 419 bool SpecialRepresentations::Contains(const char *charBytes, size_t len) const {
 420         PLATFORM_ASSERT(len <= 4);
 421         if (!startByteHasReprs[static_cast<unsigned char>(charBytes[0])])
 422                 return false;
 423         MapRepresentation::const_iterator it = mapReprs.find(KeyFromString(charBytes, len));
 424         return it != mapReprs.end();
 425 }
 426
 427 void SpecialRepresentations::Clear() {
 428         mapReprs.clear();
 429         std::fill(startByteHasReprs, startByteHasReprs+0x100, 0);
 430 }
 431
 432 void BreakFinder::Insert(int val) {
 433         if (val > nextBreak) {
 434                 const std::vector<int>::iterator it = std::lower_bound(selAndEdge.begin(), selAndEdge.end(), val);
 435                 if (it == selAndEdge.end()) {
 436                         selAndEdge.push_back(val);
 437                 } else if (*it != val) {
 438                         selAndEdge.insert(it, 1, val);
 439                 }
 440         }
 441 }
 442
 443 BreakFinder::BreakFinder(const LineLayout *ll_, const Selection *psel, Range lineRange_, int posLineStart_,
 444         int xStart, bool breakForSelection, const Document *pdoc_, const SpecialRepresentations *preprs_, const ViewStyle *pvsDraw) :
 445         ll(ll_),
 446         lineRange(lineRange_),
 447         posLineStart(posLineStart_),
 448         nextBreak(lineRange_.start),
 449         saeCurrentPos(0),
 450         saeNext(0),
 451         subBreak(-1),
 452         pdoc(pdoc_),
 453         encodingFamily(pdoc_->CodePageFamily()),
 454         preprs(preprs_) {
 455
 456         // Search for first visible break
 457         // First find the first visible character
 458         if (xStart > 0.0f)
 459                 nextBreak = ll->FindBefore(static_cast<XYPOSITION>(xStart), lineRange.start, lineRange.end);
 460         // Now back to a style break
 461         while ((nextBreak > lineRange.start) && (ll->styles[nextBreak] == ll->styles[nextBreak - 1])) {
 462                 nextBreak--;
 463         }
 464
 465         if (breakForSelection) {
 466                 SelectionPosition posStart(posLineStart);
 467                 SelectionPosition posEnd(posLineStart + lineRange.end);
 468                 SelectionSegment segmentLine(posStart, posEnd);
 469                 for (size_t r=0; r<psel->Count(); r++) {
 470                         SelectionSegment portion = psel->Range(r).Intersect(segmentLine);
 471                         if (!(portion.start == portion.end)) {
 472                                 if (portion.start.IsValid())
 473                                         Insert(portion.start.Position() - posLineStart);
 474                                 if (portion.end.IsValid())
 475                                         Insert(portion.end.Position() - posLineStart);
 476                         }
 477                 }
 478         }
 479         if (pvsDraw && pvsDraw->indicatorsSetFore > 0) {
 480                 for (Decoration *deco = pdoc->decorations.root; deco; deco = deco->next) {
 481                         if (pvsDraw->indicators[deco->indicator].OverridesTextFore()) {
 482                                 int startPos = deco->rs.EndRun(posLineStart);
 483                                 while (startPos < (posLineStart + lineRange.end)) {
 484                                         Insert(startPos - posLineStart);
 485                                         startPos = deco->rs.EndRun(startPos);
 486                                 }
 487                         }
 488                 }
 489         }
 490         Insert(ll->edgeColumn);
 491         Insert(lineRange.end);
 492         saeNext = (!selAndEdge.empty()) ? selAndEdge[0] : -1;
 493 }
 494
 495 BreakFinder::~BreakFinder() {
 496 }
 497
 498 TextSegment BreakFinder::Next() {
 499         if (subBreak == -1) {
 500                 int prev = nextBreak;
 501                 while (nextBreak < lineRange.end) {
 502                         int charWidth = 1;
 503                         if (encodingFamily == efUnicode)
 504                                 charWidth = UTF8DrawBytes(reinterpret_cast<unsigned char *>(ll->chars) + nextBreak, lineRange.end - nextBreak);
 505                         else if (encodingFamily == efDBCS)
 506                                 charWidth = pdoc->IsDBCSLeadByte(ll->chars[nextBreak]) ? 2 : 1;
 507                         const Representation *repr = preprs->RepresentationFromCharacter(ll->chars + nextBreak, charWidth);
 508                         if (((nextBreak > 0) && (ll->styles[nextBreak] != ll->styles[nextBreak - 1])) ||
 509                                         repr ||
 510                                         (nextBreak == saeNext)) {
 511                                 while ((nextBreak >= saeNext) && (saeNext < lineRange.end)) {
 512                                         saeCurrentPos++;
 513                                         saeNext = (saeCurrentPos < selAndEdge.size()) ? selAndEdge[saeCurrentPos] : lineRange.end;
 514                                 }
 515                                 if ((nextBreak > prev) || repr) {
 516                                         // Have a segment to report
 517                                         if (nextBreak == prev) {
 518                                                 nextBreak += charWidth;
 519                                         } else {
 520                                                 repr = 0;       // Optimize -> should remember repr
 521                                         }
 522                                         if ((nextBreak - prev) < lengthStartSubdivision) {
 523                                                 return TextSegment(prev, nextBreak - prev, repr);
 524                                         } else {
 525                                                 break;
 526                                         }
 527                                 }
 528                         }
 529                         nextBreak += charWidth;
 530                 }
 531                 if ((nextBreak - prev) < lengthStartSubdivision) {
 532                         return TextSegment(prev, nextBreak - prev);
 533                 }
 534                 subBreak = prev;
 535         }
 536         // Splitting up a long run from prev to nextBreak in lots of approximately lengthEachSubdivision.
 537         // For very long runs add extra breaks after spaces or if no spaces before low punctuation.
 538         int startSegment = subBreak;
 539         if ((nextBreak - subBreak) <= lengthEachSubdivision) {
 540                 subBreak = -1;
 541                 return TextSegment(startSegment, nextBreak - startSegment);
 542         } else {
 543                 subBreak += pdoc->SafeSegment(ll->chars + subBreak, nextBreak-subBreak, lengthEachSubdivision);
 544                 if (subBreak >= nextBreak) {
 545                         subBreak = -1;
 546                         return TextSegment(startSegment, nextBreak - startSegment);
 547                 } else {
 548                         return TextSegment(startSegment, subBreak - startSegment);
 549                 }
 550         }
 551 }
 552
 553 bool BreakFinder::More() const {
 554         return (subBreak >= 0) || (nextBreak < lineRange.end);
 555 }
 556
 557 PositionCacheEntry::PositionCacheEntry() :
 558         styleNumber(0), len(0), clock(0), positions(0) {
 559 }
 560
 561 void PositionCacheEntry::Set(unsigned int styleNumber_, const char *s_,
 562         unsigned int len_, XYPOSITION *positions_, unsigned int clock_) {
 563         Clear();
 564         styleNumber = styleNumber_;
 565         len = len_;
 566         clock = clock_;
 567         if (s_ && positions_) {
 568                 positions = new XYPOSITION[len + (len / 4) + 1];
 569                 for (unsigned int i=0; i<len; i++) {
 570                         positions[i] = positions_[i];
 571                 }
 572                 memcpy(reinterpret_cast<char *>(reinterpret_cast<void *>(positions + len)), s_, len);
 573         }
 574 }
 575
 576 PositionCacheEntry::~PositionCacheEntry() {
 577         Clear();
 578 }
 579
 580 void PositionCacheEntry::Clear() {
 581         delete []positions;
 582         positions = 0;
 583         styleNumber = 0;
 584         len = 0;
 585         clock = 0;
 586 }
 587
 588 bool PositionCacheEntry::Retrieve(unsigned int styleNumber_, const char *s_,
 589         unsigned int len_, XYPOSITION *positions_) const {
 590         if ((styleNumber == styleNumber_) && (len == len_) &&
 591                 (memcmp(reinterpret_cast<char *>(reinterpret_cast<void *>(positions + len)), s_, len)== 0)) {
 592                 for (unsigned int i=0; i<len; i++) {
 593                         positions_[i] = positions[i];
 594                 }
 595                 return true;
 596         } else {
 597                 return false;
 598         }
 599 }
 600
 601 unsigned int PositionCacheEntry::Hash(unsigned int styleNumber_, const char *s, unsigned int len_) {
 602         unsigned int ret = s[0] << 7;
 603         for (unsigned int i=0; i<len_; i++) {
 604                 ret *= 1000003;
 605                 ret ^= s[i];
 606         }
 607         ret *= 1000003;
 608         ret ^= len_;
 609         ret *= 1000003;
 610         ret ^= styleNumber_;
 611         return ret;
 612 }
 613
 614 bool PositionCacheEntry::NewerThan(const PositionCacheEntry &other) const {
 615         return clock > other.clock;
 616 }
 617
 618 void PositionCacheEntry::ResetClock() {
 619         if (clock > 0) {
 620                 clock = 1;
 621         }
 622 }
 623
 624 PositionCache::PositionCache() {
 625         clock = 1;
 626         pces.resize(0x400);
 627         allClear = true;
 628 }
 629
 630 PositionCache::~PositionCache() {
 631         Clear();
 632 }
 633
 634 void PositionCache::Clear() {
 635         if (!allClear) {
 636                 for (size_t i=0; i<pces.size(); i++) {
 637                         pces[i].Clear();
 638                 }
 639         }
 640         clock = 1;
 641         allClear = true;
 642 }
 643
 644 void PositionCache::SetSize(size_t size_) {
 645         Clear();
 646         pces.resize(size_);
 647 }
 648
 649 void PositionCache::MeasureWidths(Surface *surface, const ViewStyle &vstyle, unsigned int styleNumber,
 650         const char *s, unsigned int len, XYPOSITION *positions, Document *pdoc) {
 651
 652         allClear = false;
 653         size_t probe = pces.size();     // Out of bounds
 654         if ((!pces.empty()) && (len < 30)) {
 655                 // Only store short strings in the cache so it doesn't churn with
 656                 // long comments with only a single comment.
 657
 658                 // Two way associative: try two probe positions.
 659                 unsigned int hashValue = PositionCacheEntry::Hash(styleNumber, s, len);
 660                 probe = hashValue % pces.size();
 661                 if (pces[probe].Retrieve(styleNumber, s, len, positions)) {
 662                         return;
 663                 }
 664                 unsigned int probe2 = (hashValue * 37) % pces.size();
 665                 if (pces[probe2].Retrieve(styleNumber, s, len, positions)) {
 666                         return;
 667                 }
 668                 // Not found. Choose the oldest of the two slots to replace
 669                 if (pces[probe].NewerThan(pces[probe2])) {
 670                         probe = probe2;
 671                 }
 672         }
 673         if (len > BreakFinder::lengthStartSubdivision) {
 674                 // Break up into segments
 675                 unsigned int startSegment = 0;
 676                 XYPOSITION xStartSegment = 0;
 677                 while (startSegment < len) {
 678                         unsigned int lenSegment = pdoc->SafeSegment(s + startSegment, len - startSegment, BreakFinder::lengthEachSubdivision);
 679                         FontAlias fontStyle = vstyle.styles[styleNumber].font;
 680                         surface->MeasureWidths(fontStyle, s + startSegment, lenSegment, positions + startSegment);
 681                         for (unsigned int inSeg = 0; inSeg < lenSegment; inSeg++) {
 682                                 positions[startSegment + inSeg] += xStartSegment;
 683                         }
 684                         xStartSegment = positions[startSegment + lenSegment - 1];
 685                         startSegment += lenSegment;
 686                 }
 687         } else {
 688                 FontAlias fontStyle = vstyle.styles[styleNumber].font;
 689                 surface->MeasureWidths(fontStyle, s, len, positions);
 690         }
 691         if (probe < pces.size()) {
 692                 // Store into cache
 693                 clock++;
 694                 if (clock > 60000) {
 695                         // Since there are only 16 bits for the clock, wrap it round and
 696                         // reset all cache entries so none get stuck with a high clock.
 697                         for (size_t i=0; i<pces.size(); i++) {
 698                                 pces[i].ResetClock();
 699                         }
 700                         clock = 2;
 701                 }
 702                 pces[probe].Set(styleNumber, s, len, positions, clock);
 703         }
 704 }