422 lines
16 KiB
C++
422 lines
16 KiB
C++
/******************************************************************
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* LexMarkdown.cxx
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*
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* A simple Markdown lexer for scintilla.
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*
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* Includes highlighting for some extra features from the
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* Pandoc implementation; strikeout, using '#.' as a default
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* ordered list item marker, and delimited code blocks.
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*
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* Limitations:
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*
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* Standard indented code blocks are not highlighted at all,
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* as it would conflict with other indentation schemes. Use
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* delimited code blocks for blanket highlighting of an
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* entire code block. Embedded HTML is not highlighted either.
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* Blanket HTML highlighting has issues, because some Markdown
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* implementations allow Markdown markup inside of the HTML. Also,
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* there is a following blank line issue that can't be ignored,
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* explained in the next paragraph. Embedded HTML and code
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* blocks would be better supported with language specific
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* highlighting.
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*
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* The highlighting aims to accurately reflect correct syntax,
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* but a few restrictions are relaxed. Delimited code blocks are
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* highlighted, even if the line following the code block is not blank.
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* Requiring a blank line after a block, breaks the highlighting
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* in certain cases, because of the way Scintilla ends up calling
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* the lexer.
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*
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* Written by Jon Strait - jstrait@moonloop.net
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*
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* The License.txt file describes the conditions under which this
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* software may be distributed.
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*
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*****************************************************************/
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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#include <stdarg.h>
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#include <assert.h>
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#include "ILexer.h"
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#include "Scintilla.h"
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#include "SciLexer.h"
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#include "WordList.h"
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#include "LexAccessor.h"
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#include "Accessor.h"
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#include "StyleContext.h"
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#include "CharacterSet.h"
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#include "LexerModule.h"
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#ifdef SCI_NAMESPACE
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using namespace Scintilla;
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#endif
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static inline bool IsNewline(const int ch) {
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return (ch == '\n' || ch == '\r');
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}
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// True if can follow ch down to the end with possibly trailing whitespace
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static bool FollowToLineEnd(const int ch, const int state, const unsigned int endPos, StyleContext &sc) {
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unsigned int i = 0;
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while (sc.GetRelative(++i) == ch)
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;
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// Skip over whitespace
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while (IsASpaceOrTab(sc.GetRelative(i)) && sc.currentPos + i < endPos)
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++i;
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if (IsNewline(sc.GetRelative(i)) || sc.currentPos + i == endPos) {
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sc.Forward(i);
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sc.ChangeState(state);
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sc.SetState(SCE_MARKDOWN_LINE_BEGIN);
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return true;
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}
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else return false;
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}
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// Set the state on text section from current to length characters,
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// then set the rest until the newline to default, except for any characters matching token
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static void SetStateAndZoom(const int state, const int length, const int token, StyleContext &sc) {
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sc.SetState(state);
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sc.Forward(length);
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sc.SetState(SCE_MARKDOWN_DEFAULT);
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sc.Forward();
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bool started = false;
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while (sc.More() && !IsNewline(sc.ch)) {
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if (sc.ch == token && !started) {
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sc.SetState(state);
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started = true;
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}
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else if (sc.ch != token) {
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sc.SetState(SCE_MARKDOWN_DEFAULT);
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started = false;
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}
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sc.Forward();
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}
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sc.SetState(SCE_MARKDOWN_LINE_BEGIN);
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}
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// Does the previous line have more than spaces and tabs?
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static bool HasPrevLineContent(StyleContext &sc) {
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int i = 0;
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// Go back to the previous newline
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while ((--i + (int)sc.currentPos) >= 0 && !IsNewline(sc.GetRelative(i)))
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;
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while ((--i + (int)sc.currentPos) >= 0) {
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if (IsNewline(sc.GetRelative(i)))
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break;
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if (!IsASpaceOrTab(sc.GetRelative(i)))
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return true;
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}
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return false;
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}
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static bool AtTermStart(StyleContext &sc) {
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return sc.currentPos == 0 || isspacechar(sc.chPrev);
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}
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static bool IsValidHrule(const unsigned int endPos, StyleContext &sc) {
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int count = 1;
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unsigned int i = 0;
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for (;;) {
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++i;
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int c = sc.GetRelative(i);
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if (c == sc.ch)
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++count;
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// hit a terminating character
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else if (!IsASpaceOrTab(c) || sc.currentPos + i == endPos) {
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// Are we a valid HRULE
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if ((IsNewline(c) || sc.currentPos + i == endPos) &&
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count >= 3 && !HasPrevLineContent(sc)) {
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sc.SetState(SCE_MARKDOWN_HRULE);
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sc.Forward(i);
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sc.SetState(SCE_MARKDOWN_LINE_BEGIN);
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return true;
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}
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else {
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sc.SetState(SCE_MARKDOWN_DEFAULT);
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return false;
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}
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}
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}
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}
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static void ColorizeMarkdownDoc(unsigned int startPos, int length, int initStyle,
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WordList **, Accessor &styler) {
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unsigned int endPos = startPos + length;
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int precharCount = 0;
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// Don't advance on a new loop iteration and retry at the same position.
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// Useful in the corner case of having to start at the beginning file position
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// in the default state.
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bool freezeCursor = false;
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StyleContext sc(startPos, length, initStyle, styler);
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while (sc.More()) {
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// Skip past escaped characters
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if (sc.ch == '\\') {
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sc.Forward();
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continue;
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}
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// A blockquotes resets the line semantics
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if (sc.state == SCE_MARKDOWN_BLOCKQUOTE)
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sc.SetState(SCE_MARKDOWN_LINE_BEGIN);
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// Conditional state-based actions
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if (sc.state == SCE_MARKDOWN_CODE2) {
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if (sc.Match("``") && sc.GetRelative(-2) != ' ') {
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sc.Forward(2);
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sc.SetState(SCE_MARKDOWN_DEFAULT);
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}
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}
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else if (sc.state == SCE_MARKDOWN_CODE) {
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if (sc.ch == '`' && sc.chPrev != ' ')
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sc.ForwardSetState(SCE_MARKDOWN_DEFAULT);
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}
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/* De-activated because it gets in the way of other valid indentation
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* schemes, for example multiple paragraphs inside a list item.
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// Code block
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else if (sc.state == SCE_MARKDOWN_CODEBK) {
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bool d = true;
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if (IsNewline(sc.ch)) {
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if (sc.chNext != '\t') {
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for (int c = 1; c < 5; ++c) {
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if (sc.GetRelative(c) != ' ')
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d = false;
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}
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}
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}
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else if (sc.atLineStart) {
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if (sc.ch != '\t' ) {
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for (int i = 0; i < 4; ++i) {
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if (sc.GetRelative(i) != ' ')
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d = false;
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}
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}
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}
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if (!d)
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sc.SetState(SCE_MARKDOWN_LINE_BEGIN);
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}
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*/
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// Strong
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else if (sc.state == SCE_MARKDOWN_STRONG1) {
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if (sc.Match("**") && sc.chPrev != ' ') {
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sc.Forward(2);
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sc.SetState(SCE_MARKDOWN_DEFAULT);
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}
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}
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else if (sc.state == SCE_MARKDOWN_STRONG2) {
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if (sc.Match("__") && sc.chPrev != ' ') {
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sc.Forward(2);
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sc.SetState(SCE_MARKDOWN_DEFAULT);
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}
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}
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// Emphasis
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else if (sc.state == SCE_MARKDOWN_EM1) {
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if (sc.ch == '*' && sc.chPrev != ' ')
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sc.ForwardSetState(SCE_MARKDOWN_DEFAULT);
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}
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else if (sc.state == SCE_MARKDOWN_EM2) {
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if (sc.ch == '_' && sc.chPrev != ' ')
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sc.ForwardSetState(SCE_MARKDOWN_DEFAULT);
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}
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else if (sc.state == SCE_MARKDOWN_CODEBK) {
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if (sc.atLineStart && sc.Match("~~~")) {
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int i = 1;
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while (!IsNewline(sc.GetRelative(i)) && sc.currentPos + i < endPos)
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i++;
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sc.Forward(i);
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sc.SetState(SCE_MARKDOWN_DEFAULT);
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}
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}
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else if (sc.state == SCE_MARKDOWN_STRIKEOUT) {
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if (sc.Match("~~") && sc.chPrev != ' ') {
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sc.Forward(2);
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sc.SetState(SCE_MARKDOWN_DEFAULT);
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}
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}
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else if (sc.state == SCE_MARKDOWN_LINE_BEGIN) {
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// Header
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if (sc.Match("######"))
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SetStateAndZoom(SCE_MARKDOWN_HEADER6, 6, '#', sc);
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else if (sc.Match("#####"))
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SetStateAndZoom(SCE_MARKDOWN_HEADER5, 5, '#', sc);
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else if (sc.Match("####"))
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SetStateAndZoom(SCE_MARKDOWN_HEADER4, 4, '#', sc);
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else if (sc.Match("###"))
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SetStateAndZoom(SCE_MARKDOWN_HEADER3, 3, '#', sc);
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else if (sc.Match("##"))
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SetStateAndZoom(SCE_MARKDOWN_HEADER2, 2, '#', sc);
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else if (sc.Match("#")) {
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// Catch the special case of an unordered list
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if (sc.chNext == '.' && IsASpaceOrTab(sc.GetRelative(2))) {
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precharCount = 0;
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sc.SetState(SCE_MARKDOWN_PRECHAR);
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}
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else
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SetStateAndZoom(SCE_MARKDOWN_HEADER1, 1, '#', sc);
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}
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// Code block
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else if (sc.Match("~~~")) {
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if (!HasPrevLineContent(sc))
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sc.SetState(SCE_MARKDOWN_CODEBK);
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else
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sc.SetState(SCE_MARKDOWN_DEFAULT);
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}
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else if (sc.ch == '=') {
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if (HasPrevLineContent(sc) && FollowToLineEnd('=', SCE_MARKDOWN_HEADER1, endPos, sc))
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;
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else
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sc.SetState(SCE_MARKDOWN_DEFAULT);
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}
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else if (sc.ch == '-') {
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if (HasPrevLineContent(sc) && FollowToLineEnd('-', SCE_MARKDOWN_HEADER2, endPos, sc))
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;
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else {
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precharCount = 0;
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sc.SetState(SCE_MARKDOWN_PRECHAR);
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}
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}
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else if (IsNewline(sc.ch))
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sc.SetState(SCE_MARKDOWN_LINE_BEGIN);
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else {
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precharCount = 0;
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sc.SetState(SCE_MARKDOWN_PRECHAR);
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}
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}
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// The header lasts until the newline
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else if (sc.state == SCE_MARKDOWN_HEADER1 || sc.state == SCE_MARKDOWN_HEADER2 ||
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sc.state == SCE_MARKDOWN_HEADER3 || sc.state == SCE_MARKDOWN_HEADER4 ||
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sc.state == SCE_MARKDOWN_HEADER5 || sc.state == SCE_MARKDOWN_HEADER6) {
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if (IsNewline(sc.ch))
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sc.SetState(SCE_MARKDOWN_LINE_BEGIN);
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}
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// New state only within the initial whitespace
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if (sc.state == SCE_MARKDOWN_PRECHAR) {
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// Blockquote
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if (sc.ch == '>' && precharCount < 5)
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sc.SetState(SCE_MARKDOWN_BLOCKQUOTE);
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/*
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// Begin of code block
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else if (!HasPrevLineContent(sc) && (sc.chPrev == '\t' || precharCount >= 4))
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sc.SetState(SCE_MARKDOWN_CODEBK);
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*/
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// HRule - Total of three or more hyphens, asterisks, or underscores
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// on a line by themselves
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else if ((sc.ch == '-' || sc.ch == '*' || sc.ch == '_') && IsValidHrule(endPos, sc))
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;
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// Unordered list
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else if ((sc.ch == '-' || sc.ch == '*' || sc.ch == '+') && IsASpaceOrTab(sc.chNext)) {
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sc.SetState(SCE_MARKDOWN_ULIST_ITEM);
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sc.ForwardSetState(SCE_MARKDOWN_DEFAULT);
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}
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// Ordered list
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else if (IsADigit(sc.ch)) {
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int digitCount = 0;
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while (IsADigit(sc.GetRelative(++digitCount)))
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;
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if (sc.GetRelative(digitCount) == '.' &&
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IsASpaceOrTab(sc.GetRelative(digitCount + 1))) {
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sc.SetState(SCE_MARKDOWN_OLIST_ITEM);
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sc.Forward(digitCount + 1);
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sc.SetState(SCE_MARKDOWN_DEFAULT);
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}
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}
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// Alternate Ordered list
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else if (sc.ch == '#' && sc.chNext == '.' && IsASpaceOrTab(sc.GetRelative(2))) {
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sc.SetState(SCE_MARKDOWN_OLIST_ITEM);
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sc.Forward(2);
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sc.SetState(SCE_MARKDOWN_DEFAULT);
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}
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else if (sc.ch != ' ' || precharCount > 2)
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sc.SetState(SCE_MARKDOWN_DEFAULT);
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else
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++precharCount;
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}
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// New state anywhere in doc
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if (sc.state == SCE_MARKDOWN_DEFAULT) {
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if (sc.atLineStart && sc.ch == '#') {
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sc.SetState(SCE_MARKDOWN_LINE_BEGIN);
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freezeCursor = true;
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}
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// Links and Images
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if (sc.Match("![") || sc.ch == '[') {
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int i = 0, j = 0, k = 0;
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int len = endPos - sc.currentPos;
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while (i < len && (sc.GetRelative(++i) != ']' || sc.GetRelative(i - 1) == '\\'))
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;
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if (sc.GetRelative(i) == ']') {
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j = i;
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if (sc.GetRelative(++i) == '(') {
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while (i < len && (sc.GetRelative(++i) != ')' || sc.GetRelative(i - 1) == '\\'))
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;
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if (sc.GetRelative(i) == ')')
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k = i;
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}
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else if (sc.GetRelative(i) == '[' || sc.GetRelative(++i) == '[') {
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while (i < len && (sc.GetRelative(++i) != ']' || sc.GetRelative(i - 1) == '\\'))
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;
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if (sc.GetRelative(i) == ']')
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k = i;
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}
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}
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// At least a link text
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if (j) {
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sc.SetState(SCE_MARKDOWN_LINK);
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sc.Forward(j);
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// Also has a URL or reference portion
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if (k)
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sc.Forward(k - j);
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sc.ForwardSetState(SCE_MARKDOWN_DEFAULT);
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}
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}
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// Code - also a special case for alternate inside spacing
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if (sc.Match("``") && sc.GetRelative(3) != ' ' && AtTermStart(sc)) {
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sc.SetState(SCE_MARKDOWN_CODE2);
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sc.Forward();
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}
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else if (sc.ch == '`' && sc.chNext != ' ' && AtTermStart(sc)) {
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sc.SetState(SCE_MARKDOWN_CODE);
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}
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// Strong
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else if (sc.Match("**") && sc.GetRelative(2) != ' ' && AtTermStart(sc)) {
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sc.SetState(SCE_MARKDOWN_STRONG1);
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sc.Forward();
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}
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else if (sc.Match("__") && sc.GetRelative(2) != ' ' && AtTermStart(sc)) {
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sc.SetState(SCE_MARKDOWN_STRONG2);
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sc.Forward();
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}
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// Emphasis
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else if (sc.ch == '*' && sc.chNext != ' ' && AtTermStart(sc)) {
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sc.SetState(SCE_MARKDOWN_EM1);
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}
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else if (sc.ch == '_' && sc.chNext != ' ' && AtTermStart(sc)) {
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sc.SetState(SCE_MARKDOWN_EM2);
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}
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// Strikeout
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else if (sc.Match("~~") && sc.GetRelative(2) != ' ' && AtTermStart(sc)) {
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sc.SetState(SCE_MARKDOWN_STRIKEOUT);
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sc.Forward();
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}
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// Beginning of line
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else if (IsNewline(sc.ch)) {
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sc.SetState(SCE_MARKDOWN_LINE_BEGIN);
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}
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}
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// Advance if not holding back the cursor for this iteration.
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if (!freezeCursor)
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sc.Forward();
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freezeCursor = false;
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}
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sc.Complete();
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}
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LexerModule lmMarkdown(SCLEX_MARKDOWN, ColorizeMarkdownDoc, "markdown");
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