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LexPython.cxx

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// Scintilla source code edit control
/** @file LexPython.cxx
 ** Lexer for Python.
 **/
// Copyright 1998-2002 by Neil Hodgson <neilh@scintilla.org>
// The License.txt file describes the conditions under which this software may be distributed.

#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <stdio.h>
#include <stdarg.h>

#include "Platform.h"

#include "PropSet.h"
#include "Accessor.h"
#include "StyleContext.h"
#include "KeyWords.h"
#include "Scintilla.h"
#include "SciLexer.h"

enum kwType { kwOther, kwClass, kwDef, kwImport };

static bool IsPyComment(Accessor &styler, int pos, int len) {
      return len > 0 && styler[pos] == '#';
}

static bool IsPyStringStart(int ch, int chNext, int chNext2) {
      if (ch == '\'' || ch == '"')
            return true;
      if (ch == 'u' || ch == 'U') {
            if (chNext == '"' || chNext == '\'')
                  return true;
            if ((chNext == 'r' || chNext == 'R') && (chNext2 == '"' || chNext2 == '\''))
                  return true;
      }
      if ((ch == 'r' || ch == 'R') && (chNext == '"' || chNext == '\''))
            return true;

      return false;
}

/* Return the state to use for the string starting at i; *nextIndex will be set to the first index following the quote(s) */
static int GetPyStringState(Accessor &styler, int i, unsigned int *nextIndex) {
      char ch = styler.SafeGetCharAt(i);
      char chNext = styler.SafeGetCharAt(i + 1);

      // Advance beyond r, u, or ur prefix, but bail if there are any unexpected chars
      if (ch == 'r' || ch == 'R') {
            i++;
            ch = styler.SafeGetCharAt(i);
            chNext = styler.SafeGetCharAt(i + 1);
      } else if (ch == 'u' || ch == 'U') {
            if (chNext == 'r' || chNext == 'R')
                  i += 2;
            else
                  i += 1;
            ch = styler.SafeGetCharAt(i);
            chNext = styler.SafeGetCharAt(i + 1);
      }

      if (ch != '"' && ch != '\'') {
            *nextIndex = i + 1;
            return SCE_P_DEFAULT;
      }

      if (ch == chNext && ch == styler.SafeGetCharAt(i + 2)) {
            *nextIndex = i + 3;

            if (ch == '"')
                  return SCE_P_TRIPLEDOUBLE;
            else
                  return SCE_P_TRIPLE;
      } else {
            *nextIndex = i + 1;

            if (ch == '"')
                  return SCE_P_STRING;
            else
                  return SCE_P_CHARACTER;
      }
}

static inline bool IsAWordChar(int ch) {
      return (ch < 0x80) && (isalnum(ch) || ch == '.' || ch == '_');
}

static inline bool IsAWordStart(int ch) {
      return (ch < 0x80) && (isalnum(ch) || ch == '_');
}

static void ColourisePyDoc(unsigned int startPos, int length, int initStyle,
                           WordList *keywordlists[], Accessor &styler) {

      int endPos = startPos + length;

      // Backtrack to previous line in case need to fix its tab whinging
      int lineCurrent = styler.GetLine(startPos);
      if (startPos > 0) {
            if (lineCurrent > 0) {
                  lineCurrent--;
                  startPos = styler.LineStart(lineCurrent);
                  if (startPos == 0)
                        initStyle = SCE_P_DEFAULT;
                  else
                        initStyle = styler.StyleAt(startPos - 1);
            }
      }

      WordList &keywords = *keywordlists[0];

      const int whingeLevel = styler.GetPropertyInt("tab.timmy.whinge.level");

      initStyle = initStyle & 31;
      if (initStyle == SCE_P_STRINGEOL) {
            initStyle = SCE_P_DEFAULT;
      }

      kwType kwLast = kwOther;
      int spaceFlags = 0;
      styler.IndentAmount(lineCurrent, &spaceFlags, IsPyComment);
      bool hexadecimal = false;

      // Python uses a different mask because bad indentation is marked by oring with 32
      StyleContext sc(startPos, endPos - startPos, initStyle, styler, 0x7f);

      for (; sc.More(); sc.Forward()) {

            if (sc.atLineStart) {
                  const char chBad = static_cast<char>(64);
                  const char chGood = static_cast<char>(0);
                  char chFlags = chGood;
                  if (whingeLevel == 1) {
                        chFlags = (spaceFlags & wsInconsistent) ? chBad : chGood;
                  } else if (whingeLevel == 2) {
                        chFlags = (spaceFlags & wsSpaceTab) ? chBad : chGood;
                  } else if (whingeLevel == 3) {
                        chFlags = (spaceFlags & wsSpace) ? chBad : chGood;
                  } else if (whingeLevel == 4) {
                        chFlags = (spaceFlags & wsTab) ? chBad : chGood;
                  }
                  sc.SetState(sc.state);
                  styler.SetFlags(chFlags, static_cast<char>(sc.state));
            }

            if (sc.atLineEnd) {
                  if ((sc.state == SCE_P_DEFAULT) ||
                          (sc.state == SCE_P_TRIPLE) ||
                          (sc.state == SCE_P_TRIPLEDOUBLE)) {
                        // Perform colourisation of white space and triple quoted strings at end of each line to allow
                        // tab marking to work inside white space and triple quoted strings
                        sc.SetState(sc.state);
                  }
                  lineCurrent++;
                  styler.IndentAmount(lineCurrent, &spaceFlags, IsPyComment);
                  if ((sc.state == SCE_P_STRING) || (sc.state == SCE_P_CHARACTER)) {
                        sc.ChangeState(SCE_P_STRINGEOL);
                        sc.ForwardSetState(SCE_P_DEFAULT);
                  }
                  if (!sc.More())
                        break;
            }

            bool needEOLCheck = false;

            // Check for a state end
            if (sc.state == SCE_P_OPERATOR) {
                  kwLast = kwOther;
                  sc.SetState(SCE_P_DEFAULT);
            } else if (sc.state == SCE_P_NUMBER) {
                  if (!IsAWordChar(sc.ch) &&
                          !(!hexadecimal && ((sc.ch == '+' || sc.ch == '-') && (sc.chPrev == 'e' || sc.chPrev == 'E')))) {
                        sc.SetState(SCE_P_DEFAULT);
                  }
            } else if (sc.state == SCE_P_IDENTIFIER) {
                  if ((sc.ch == '.') || (!IsAWordChar(sc.ch))) {
                        char s[100];
                        sc.GetCurrent(s, sizeof(s));
                        int style = SCE_P_IDENTIFIER;
                        if ((kwLast == kwImport) && (strcmp(s, "as") == 0)) {
                              style = SCE_P_WORD;
                        } else if (keywords.InList(s)) {
                              style = SCE_P_WORD;
                        } else if (kwLast == kwClass) {
                              style = SCE_P_CLASSNAME;
                        } else if (kwLast == kwDef) {
                              style = SCE_P_DEFNAME;
                        }
                        sc.ChangeState(style);
                        sc.SetState(SCE_P_DEFAULT);
                        if (style == SCE_P_WORD) {
                              if (0 == strcmp(s, "class"))
                                    kwLast = kwClass;
                              else if (0 == strcmp(s, "def"))
                                    kwLast = kwDef;
                              else if (0 == strcmp(s, "import"))
                                    kwLast = kwImport;
                              else
                                    kwLast = kwOther;
                        } else if (style == SCE_P_CLASSNAME) {
                              kwLast = kwOther;
                        } else if (style == SCE_P_DEFNAME) {
                              kwLast = kwOther;
                        }
                  }
            } else if ((sc.state == SCE_P_COMMENTLINE) || (sc.state == SCE_P_COMMENTBLOCK)) {
                  if (sc.ch == '\r' || sc.ch == '\n') {
                        sc.SetState(SCE_P_DEFAULT);
                  }
            } else if ((sc.state == SCE_P_STRING) || (sc.state == SCE_P_CHARACTER)) {
                  if (sc.ch == '\\') {
                        if ((sc.chNext == '\r') && (sc.GetRelative(2) == '\n')) {
                              sc.Forward();
                        }
                        sc.Forward();
                  } else if ((sc.state == SCE_P_STRING) && (sc.ch == '\"')) {
                        sc.ForwardSetState(SCE_P_DEFAULT);
                        needEOLCheck = true;
                  } else if ((sc.state == SCE_P_CHARACTER) && (sc.ch == '\'')) {
                        sc.ForwardSetState(SCE_P_DEFAULT);
                        needEOLCheck = true;
                  }
            } else if (sc.state == SCE_P_TRIPLE) {
                  if (sc.ch == '\\') {
                        sc.Forward();
                  } else if (sc.Match("\'\'\'")) {
                        sc.Forward();
                        sc.Forward();
                        sc.ForwardSetState(SCE_P_DEFAULT);
                        needEOLCheck = true;
                  }
            } else if (sc.state == SCE_P_TRIPLEDOUBLE) {
                  if (sc.ch == '\\') {
                        sc.Forward();
                  } else if (sc.Match("\"\"\"")) {
                        sc.Forward();
                        sc.Forward();
                        sc.ForwardSetState(SCE_P_DEFAULT);
                        needEOLCheck = true;
                  }
            }

            // State exit code may have moved on to end of line
            if (needEOLCheck && sc.atLineEnd) {
                  lineCurrent++;
                  styler.IndentAmount(lineCurrent, &spaceFlags, IsPyComment);
                  if (!sc.More())
                        break;
            }

            // Check for a new state starting character
            if (sc.state == SCE_P_DEFAULT) {
                  if (IsADigit(sc.ch) || (sc.ch == '.' && IsADigit(sc.chNext))) {
                        if (sc.ch == '0' && (sc.chNext == 'x' || sc.chNext == 'X')) {
                              hexadecimal = true;
                        } else {
                              hexadecimal = false;
                        }
                        sc.SetState(SCE_P_NUMBER);
                  } else if (isascii(sc.ch) && isoperator(static_cast<char>(sc.ch)) || sc.ch == '`') {
                        sc.SetState(SCE_P_OPERATOR);
                  } else if (sc.ch == '#') {
                        sc.SetState(sc.chNext == '#' ? SCE_P_COMMENTBLOCK : SCE_P_COMMENTLINE);
                  } else if (IsPyStringStart(sc.ch, sc.chNext, sc.GetRelative(2))) {
                        unsigned int nextIndex = 0;
                        sc.SetState(GetPyStringState(styler, sc.currentPos, &nextIndex));
                        while (nextIndex > (sc.currentPos + 1)) {
                              sc.Forward();
                        }
                  } else if (IsAWordStart(sc.ch)) {
                        sc.SetState(SCE_P_IDENTIFIER);
                  }
            }
      }
      sc.Complete();
}

static bool IsCommentLine(int line, Accessor &styler) {
      int pos = styler.LineStart(line);
      int eol_pos = styler.LineStart(line + 1) - 1;
      for (int i = pos; i < eol_pos; i++) {
            char ch = styler[i];
            if (ch == '#')
                  return true;
            else if (ch != ' ' && ch != '\t')
                  return false;
      }
      return false;
}

static bool IsQuoteLine(int line, Accessor &styler) {
      int style = styler.StyleAt(styler.LineStart(line)) & 31;
      return ((style == SCE_P_TRIPLE) || (style == SCE_P_TRIPLEDOUBLE));
}


static void FoldPyDoc(unsigned int startPos, int length, int /*initStyle - unused*/,
                      WordList *[], Accessor &styler) {
      const int maxPos = startPos + length;
      const int maxLines = styler.GetLine(maxPos - 1);             // Requested last line
      const int docLines = styler.GetLine(styler.Length() - 1);  // Available last line
      const bool foldComment = styler.GetPropertyInt("fold.comment.python") != 0;
      const bool foldQuotes = styler.GetPropertyInt("fold.quotes.python") != 0;

      // Backtrack to previous non-blank line so we can determine indent level
      // for any white space lines (needed esp. within triple quoted strings)
      // and so we can fix any preceding fold level (which is why we go back
      // at least one line in all cases)
      int spaceFlags = 0;
      int lineCurrent = styler.GetLine(startPos);
      int indentCurrent = styler.IndentAmount(lineCurrent, &spaceFlags, NULL);
      while (lineCurrent > 0) {
            lineCurrent--;
            indentCurrent = styler.IndentAmount(lineCurrent, &spaceFlags, NULL);
            if (!(indentCurrent & SC_FOLDLEVELWHITEFLAG) &&
                    (!IsCommentLine(lineCurrent, styler)) &&
                    (!IsQuoteLine(lineCurrent, styler)))
                  break;
      }
      int indentCurrentLevel = indentCurrent & SC_FOLDLEVELNUMBERMASK;

      // Set up initial loop state
      startPos = styler.LineStart(lineCurrent);
      int prev_state = SCE_P_DEFAULT & 31;
      if (lineCurrent >= 1)
            prev_state = styler.StyleAt(startPos - 1) & 31;
      int prevQuote = foldQuotes && ((prev_state == SCE_P_TRIPLE) || (prev_state == SCE_P_TRIPLEDOUBLE));
      int prevComment = 0;
      if (lineCurrent >= 1)
            prevComment = foldComment && IsCommentLine(lineCurrent - 1, styler);

      // Process all characters to end of requested range or end of any triple quote
      // or comment that hangs over the end of the range.  Cap processing in all cases
      // to end of document (in case of unclosed quote or comment at end).
      while ((lineCurrent <= docLines) && ((lineCurrent <= maxLines) || prevQuote || prevComment)) {

            // Gather info
            int lev = indentCurrent;
            int lineNext = lineCurrent + 1;
            int indentNext = indentCurrent;
            int quote = false;
            if (lineNext <= docLines) {
                  // Information about next line is only available if not at end of document
                  indentNext = styler.IndentAmount(lineNext, &spaceFlags, NULL);
                  int style = styler.StyleAt(styler.LineStart(lineNext)) & 31;
                  quote = foldQuotes && ((style == SCE_P_TRIPLE) || (style == SCE_P_TRIPLEDOUBLE));
            }
            const int quote_start = (quote && !prevQuote);
            const int quote_continue = (quote && prevQuote);
            const int comment = foldComment && IsCommentLine(lineCurrent, styler);
            const int comment_start = (comment && !prevComment && (lineNext <= docLines) &&
                                       IsCommentLine(lineNext, styler) && (lev > SC_FOLDLEVELBASE));
            const int comment_continue = (comment && prevComment);
            if ((!quote || !prevQuote) && !comment)
                  indentCurrentLevel = indentCurrent & SC_FOLDLEVELNUMBERMASK;
            if (quote)
                  indentNext = indentCurrentLevel;
            if (indentNext & SC_FOLDLEVELWHITEFLAG)
                  indentNext = SC_FOLDLEVELWHITEFLAG | indentCurrentLevel;

            if (quote_start) {
                  // Place fold point at start of triple quoted string
                  lev |= SC_FOLDLEVELHEADERFLAG;
            } else if (quote_continue || prevQuote) {
                  // Add level to rest of lines in the string
                  lev = lev + 1;
            } else if (comment_start) {
                  // Place fold point at start of a block of comments
                  lev |= SC_FOLDLEVELHEADERFLAG;
            } else if (comment_continue) {
                  // Add level to rest of lines in the block
                  lev = lev + 1;
            }

            // Skip past any blank lines for next indent level info; we skip also
            // comments (all comments, not just those starting in column 0)
            // which effectively folds them into surrounding code rather
            // than screwing up folding.

            while (!quote &&
                    (lineNext < docLines) &&
                    ((indentNext & SC_FOLDLEVELWHITEFLAG) ||
                     (lineNext <= docLines && IsCommentLine(lineNext, styler)))) {

                  lineNext++;
                  indentNext = styler.IndentAmount(lineNext, &spaceFlags, NULL);
            }

            const int levelAfterComments = indentNext & SC_FOLDLEVELNUMBERMASK;
            const int levelBeforeComments = Platform::Maximum(indentCurrentLevel,levelAfterComments);

            // Now set all the indent levels on the lines we skipped
            // Do this from end to start.  Once we encounter one line
            // which is indented more than the line after the end of
            // the comment-block, use the level of the block before

            int skipLine = lineNext;
            int skipLevel = levelAfterComments;

            while (--skipLine > lineCurrent) {
                  int skipLineIndent = styler.IndentAmount(skipLine, &spaceFlags, NULL);

                  if ((skipLineIndent & SC_FOLDLEVELNUMBERMASK) > levelAfterComments)
                        skipLevel = levelBeforeComments;

                  int whiteFlag = skipLineIndent & SC_FOLDLEVELWHITEFLAG;

                  styler.SetLevel(skipLine, skipLevel | whiteFlag);
            }

            // Set fold header on non-quote/non-comment line
            if (!quote && !comment && !(indentCurrent & SC_FOLDLEVELWHITEFLAG) ) {
                  if ((indentCurrent & SC_FOLDLEVELNUMBERMASK) < (indentNext & SC_FOLDLEVELNUMBERMASK))
                        lev |= SC_FOLDLEVELHEADERFLAG;
            }

            // Keep track of triple quote and block comment state of previous line
            prevQuote = quote;
            prevComment = comment_start || comment_continue;

            // Set fold level for this line and move to next line
            styler.SetLevel(lineCurrent, lev);
            indentCurrent = indentNext;
            lineCurrent = lineNext;
      }

      // NOTE: Cannot set level of last line here because indentCurrent doesn't have
      // header flag set; the loop above is crafted to take care of this case!
      //styler.SetLevel(lineCurrent, indentCurrent);
}

static const char * const pythonWordListDesc[] = {
      "Keywords",
      0
};

LexerModule lmPython(SCLEX_PYTHON, ColourisePyDoc, "python", FoldPyDoc,
                               pythonWordListDesc);

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