// Scintilla source code edit control
/** @file Lexr.cxx
 ** Lexer for R, S, SPlus Statistics Program (Heavily derived from CPP Lexer).
 **
 **/
// 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 <stdio.h>
#include <stdarg.h>
#include <assert.h>
#include <ctype.h>

#include "ILexer.h"
#include "Scintilla.h"
#include "SciLexer.h"

#include "WordList.h"
#include "LexAccessor.h"
#include "Accessor.h"
#include "StyleContext.h"
#include "CharacterSet.h"
#include "LexerModule.h"

#ifdef SCI_NAMESPACE
using namespace Scintilla;
#endif

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

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

static inline bool IsAnOperator(const int ch) {
    if (isascii(ch) && isalnum(ch))
        return false;
    // '.' left out as it is used to make up numbers
    if (ch == '-' || ch == '+' || ch == '!' || ch == '~' ||
            ch == '?' || ch == ':' || ch == '*' || ch == '/' ||
            ch == '^' || ch == '<' || ch == '>' || ch == '=' ||
            ch == '&' || ch == '|' || ch == '$' || ch == '(' ||
            ch == ')' || ch == '}' || ch == '{' || ch == '[' ||
        ch == ']')
        return true;
    return false;
}

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

    WordList &keywords   = *keywordlists[0];
    WordList &keywords2 = *keywordlists[1];
    WordList &keywords3 = *keywordlists[2];


    // Do not leak onto next line
    if (initStyle == SCE_R_INFIXEOL)
        initStyle = SCE_R_DEFAULT;


    StyleContext sc(startPos, length, initStyle, styler);

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

        if (sc.atLineStart && (sc.state == SCE_R_STRING)) {
            // Prevent SCE_R_STRINGEOL from leaking back to previous line
            sc.SetState(SCE_R_STRING);
        }

        // Determine if the current state should terminate.
        if (sc.state == SCE_R_OPERATOR) {
            sc.SetState(SCE_R_DEFAULT);
        } else if (sc.state == SCE_R_NUMBER) {
            if (!IsADigit(sc.ch) && !(sc.ch == '.' && IsADigit(sc.chNext))) {
                sc.SetState(SCE_R_DEFAULT);
            }
        } else if (sc.state == SCE_R_IDENTIFIER) {
            if (!IsAWordChar(sc.ch)) {
                char s[100];
                sc.GetCurrent(s, sizeof(s));
                if (keywords.InList(s)) {
                    sc.ChangeState(SCE_R_KWORD);
                } else if  (keywords2.InList(s)) {
                    sc.ChangeState(SCE_R_BASEKWORD);
                } else if  (keywords3.InList(s)) {
                    sc.ChangeState(SCE_R_OTHERKWORD);
                }
                sc.SetState(SCE_R_DEFAULT);
            }
        } else if (sc.state == SCE_R_COMMENT) {
            if (sc.ch == '\r' || sc.ch == '\n') {
                sc.SetState(SCE_R_DEFAULT);
            }
        } else if (sc.state == SCE_R_STRING) {
            if (sc.ch == '\\') {
                if (sc.chNext == '\"' || sc.chNext == '\'' || sc.chNext == '\\') {
                    sc.Forward();
                }
            } else if (sc.ch == '\"') {
                sc.ForwardSetState(SCE_R_DEFAULT);
            }
        } else if (sc.state == SCE_R_INFIX) {
            if (sc.ch == '%') {
                sc.ForwardSetState(SCE_R_DEFAULT);
            } else if (sc.atLineEnd) {
                sc.ChangeState(SCE_R_INFIXEOL);
                sc.ForwardSetState(SCE_R_DEFAULT);
            }
        }else if (sc.state == SCE_R_STRING2) {
            if (sc.ch == '\\') {
                if (sc.chNext == '\"' || sc.chNext == '\'' || sc.chNext == '\\') {
                    sc.Forward();
                }
            } else if (sc.ch == '\'') {
                sc.ForwardSetState(SCE_R_DEFAULT);
            }
        }

        // Determine if a new state should be entered.
        if (sc.state == SCE_R_DEFAULT) {
            if (IsADigit(sc.ch) || (sc.ch == '.' && IsADigit(sc.chNext))) {
                sc.SetState(SCE_R_NUMBER);
            } else if (IsAWordStart(sc.ch) ) {
                sc.SetState(SCE_R_IDENTIFIER);
            } else if (sc.Match('#')) {
                    sc.SetState(SCE_R_COMMENT);
            } else if (sc.ch == '\"') {
                sc.SetState(SCE_R_STRING);
            } else if (sc.ch == '%') {
                sc.SetState(SCE_R_INFIX);
            } else if (sc.ch == '\'') {
                sc.SetState(SCE_R_STRING2);
            } else if (IsAnOperator(sc.ch)) {
                sc.SetState(SCE_R_OPERATOR);
            }
        }
    }
    sc.Complete();
}

// Store both the current line's fold level and the next lines in the
// level store to make it easy to pick up with each increment
// and to make it possible to fiddle the current level for "} else {".
static void FoldRDoc(unsigned int startPos, int length, int, WordList *[],
                       Accessor &styler) {
    bool foldCompact = styler.GetPropertyInt("fold.compact", 1) != 0;
    bool foldAtElse = styler.GetPropertyInt("fold.at.else", 0) != 0;
    unsigned int endPos = startPos + length;
    int visibleChars = 0;
    int lineCurrent = styler.GetLine(startPos);
    int levelCurrent = SC_FOLDLEVELBASE;
    if (lineCurrent > 0)
        levelCurrent = styler.LevelAt(lineCurrent-1) >> 16;
    int levelMinCurrent = levelCurrent;
    int levelNext = levelCurrent;
    char chNext = styler[startPos];
    int styleNext = styler.StyleAt(startPos);
    for (unsigned int i = startPos; i < endPos; i++) {
        char ch = chNext;
        chNext = styler.SafeGetCharAt(i + 1);
        int style = styleNext;
        styleNext = styler.StyleAt(i + 1);
        bool atEOL = (ch == '\r' && chNext != '\n') || (ch == '\n');
        if (style == SCE_R_OPERATOR) {
            if (ch == '{') {
                // Measure the minimum before a '{' to allow
                // folding on "} else {"
                if (levelMinCurrent > levelNext) {
                    levelMinCurrent = levelNext;
                }
                levelNext++;
            } else if (ch == '}') {
                levelNext--;
            }
        }
        if (atEOL) {
            int levelUse = levelCurrent;
            if (foldAtElse) {
                levelUse = levelMinCurrent;
            }
            int lev = levelUse | levelNext << 16;
            if (visibleChars == 0 && foldCompact)
                lev |= SC_FOLDLEVELWHITEFLAG;
            if (levelUse < levelNext)
                lev |= SC_FOLDLEVELHEADERFLAG;
            if (lev != styler.LevelAt(lineCurrent)) {
                styler.SetLevel(lineCurrent, lev);
            }
            lineCurrent++;
            levelCurrent = levelNext;
            levelMinCurrent = levelCurrent;
            visibleChars = 0;
        }
        if (!isspacechar(ch))
            visibleChars++;
    }
}


static const char * const RWordLists[] = {
            "Language Keywords",
            "Base / Default package function",
            "Other Package Functions",
            "Unused",
            "Unused",
            0,
        };



LexerModule lmR(SCLEX_R, ColouriseRDoc, "r", FoldRDoc, RWordLists);
