// Scintilla source code edit control
/** @file LexCaml.cxx
 ** Lexer for Objective Caml.
 **/
// Copyright 2005-2009 by Robert Roessler <robertr@rftp.com>
// The License.txt file describes the conditions under which this software may be distributed.
/*	Release History
	20050204 Initial release.
	20050205 Quick compiler standards/"cleanliness" adjustment.
	20050206 Added cast for IsLeadByte().
	20050209 Changes to "external" build support.
	20050306 Fix for 1st-char-in-doc "corner" case.
	20050502 Fix for [harmless] one-past-the-end coloring.
	20050515 Refined numeric token recognition logic.
	20051125 Added 2nd "optional" keywords class.
	20051129 Support "magic" (read-only) comments for RCaml.
	20051204 Swtich to using StyleContext infrastructure.
	20090629 Add full Standard ML '97 support.
*/

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

#include <string>
#include <string_view>

#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"

#if defined(__clang__)
#pragma clang diagnostic ignored "-Wcomma"
#endif

//	Since the Microsoft __iscsym[f] funcs are not ANSI...
inline int  iscaml(int c) {return isalnum(c) || c == '_';}
inline int iscamlf(int c) {return isalpha(c) || c == '_';}

static const int baseT[24] = {
	0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,	/* A - L */
	0, 0, 8, 0, 0, 0, 0, 0, 0, 0, 0,16	/* M - X */
};

using namespace Lexilla;

static void ColouriseCamlDoc(
	Sci_PositionU startPos, Sci_Position length,
	int initStyle,
	WordList *keywordlists[],
	Accessor &styler)
{
	// initialize styler
	StyleContext sc(startPos, length, initStyle, styler);

	Sci_PositionU chToken = 0;
	int chBase = 0, chLit = 0;
	WordList& keywords  = *keywordlists[0];
	WordList& keywords2 = *keywordlists[1];
	WordList& keywords3 = *keywordlists[2];
	const bool isSML = keywords.InList("andalso");
	const int useMagic = styler.GetPropertyInt("lexer.caml.magic", 0);

	// set up [initial] state info (terminating states that shouldn't "bleed")
	const int state_ = sc.state & 0x0f;
	if (state_ <= SCE_CAML_CHAR
		|| (isSML && state_ == SCE_CAML_STRING))
		sc.state = SCE_CAML_DEFAULT;
	int nesting = (state_ >= SCE_CAML_COMMENT)? (state_ - SCE_CAML_COMMENT): 0;

	// foreach char in range...
	while (sc.More()) {
		// set up [per-char] state info
		int state2 = -1;				// (ASSUME no state change)
		Sci_Position chColor = sc.currentPos - 1;// (ASSUME standard coloring range)
		bool advance = true;			// (ASSUME scanner "eats" 1 char)

		// step state machine
		switch (sc.state & 0x0f) {
		case SCE_CAML_DEFAULT:
			chToken = sc.currentPos;	// save [possible] token start (JIC)
			// it's wide open; what do we have?
			if (iscamlf(sc.ch))
				state2 = SCE_CAML_IDENTIFIER;
			else if (!isSML && sc.Match('`') && iscamlf(sc.chNext))
				state2 = SCE_CAML_TAGNAME;
			else if (!isSML && sc.Match('#') && isdigit(sc.chNext))
				state2 = SCE_CAML_LINENUM;
			else if (isdigit(sc.ch)) {
				// it's a number, assume base 10
				state2 = SCE_CAML_NUMBER, chBase = 10;
				if (sc.Match('0')) {
					// there MAY be a base specified...
					const char* baseC = "bBoOxX";
					if (isSML) {
						if (sc.chNext == 'w')
							sc.Forward();	// (consume SML "word" indicator)
						baseC = "x";
					}
					// ... change to specified base AS REQUIRED
					if (strchr(baseC, sc.chNext))
						chBase = baseT[tolower(sc.chNext) - 'a'], sc.Forward();
				}
			} else if (!isSML && sc.Match('\''))	// (Caml char literal?)
				state2 = SCE_CAML_CHAR, chLit = 0;
			else if (isSML && sc.Match('#', '"'))	// (SML char literal?)
				state2 = SCE_CAML_CHAR, sc.Forward();
			else if (sc.Match('"'))
				state2 = SCE_CAML_STRING;
			else if (sc.Match('(', '*'))
				state2 = SCE_CAML_COMMENT, sc.Forward(), sc.ch = ' '; // (*)...
			else if (strchr("!?~"			/* Caml "prefix-symbol" */
					"=<>@^|&+-*/$%"			/* Caml "infix-symbol" */
					"()[]{};,:.#", sc.ch)	// Caml "bracket" or ;,:.#
											// SML "extra" ident chars
				|| (isSML && (sc.Match('\\') || sc.Match('`'))))
				state2 = SCE_CAML_OPERATOR;
			break;

		case SCE_CAML_IDENTIFIER:
			// [try to] interpret as [additional] identifier char
			if (!(iscaml(sc.ch) || sc.Match('\''))) {
				const Sci_Position n = sc.currentPos - chToken;
				if (n < 24) {
					// length is believable as keyword, [re-]construct token
					char t[24];
					for (Sci_Position i = -n; i < 0; i++)
						t[n + i] = static_cast<char>(sc.GetRelative(i));
					t[n] = '\0';
					// special-case "_" token as KEYWORD
					if ((n == 1 && sc.chPrev == '_') || keywords.InList(t))
						sc.ChangeState(SCE_CAML_KEYWORD);
					else if (keywords2.InList(t))
						sc.ChangeState(SCE_CAML_KEYWORD2);
					else if (keywords3.InList(t))
						sc.ChangeState(SCE_CAML_KEYWORD3);
				}
				state2 = SCE_CAML_DEFAULT, advance = false;
			}
			break;

		case SCE_CAML_TAGNAME:
			// [try to] interpret as [additional] tagname char
			if (!(iscaml(sc.ch) || sc.Match('\'')))
				state2 = SCE_CAML_DEFAULT, advance = false;
			break;

		/*case SCE_CAML_KEYWORD:
		case SCE_CAML_KEYWORD2:
		case SCE_CAML_KEYWORD3:
			// [try to] interpret as [additional] keyword char
			if (!iscaml(ch))
				state2 = SCE_CAML_DEFAULT, advance = false;
			break;*/

		case SCE_CAML_LINENUM:
			// [try to] interpret as [additional] linenum directive char
			if (!isdigit(sc.ch))
				state2 = SCE_CAML_DEFAULT, advance = false;
			break;

		case SCE_CAML_OPERATOR: {
			// [try to] interpret as [additional] operator char
			const char* o = 0;
			if (iscaml(sc.ch) || isspace(sc.ch)			// ident or whitespace
				|| (o = strchr(")]};,\'\"#", sc.ch),o)	// "termination" chars
				|| (!isSML && sc.Match('`'))			// Caml extra term char
				|| (!strchr("!$%&*+-./:<=>?@^|~", sc.ch)// "operator" chars
														// SML extra ident chars
					&& !(isSML && (sc.Match('\\') || sc.Match('`'))))) {
				// check for INCLUSIVE termination
				if (o && strchr(")]};,", sc.ch)) {
					if ((sc.Match(')') && sc.chPrev == '(')
						|| (sc.Match(']') && sc.chPrev == '['))
						// special-case "()" and "[]" tokens as KEYWORDS
						sc.ChangeState(SCE_CAML_KEYWORD);
					chColor++;
				} else
					advance = false;
				state2 = SCE_CAML_DEFAULT;
			}
			break;
		}

		case SCE_CAML_NUMBER:
			// [try to] interpret as [additional] numeric literal char
			if ((!isSML && sc.Match('_')) || IsADigit(sc.ch, chBase))
				break;
			// how about an integer suffix?
			if (!isSML && (sc.Match('l') || sc.Match('L') || sc.Match('n'))
				&& (sc.chPrev == '_' || IsADigit(sc.chPrev, chBase)))
				break;
			// or a floating-point literal?
			if (chBase == 10) {
				// with a decimal point?
				if (sc.Match('.')
					&& ((!isSML && sc.chPrev == '_')
						|| IsADigit(sc.chPrev, chBase)))
					break;
				// with an exponent? (I)
				if ((sc.Match('e') || sc.Match('E'))
					&& ((!isSML && (sc.chPrev == '.' || sc.chPrev == '_'))
						|| IsADigit(sc.chPrev, chBase)))
					break;
				// with an exponent? (II)
				if (((!isSML && (sc.Match('+') || sc.Match('-')))
						|| (isSML && sc.Match('~')))
					&& (sc.chPrev == 'e' || sc.chPrev == 'E'))
					break;
			}
			// it looks like we have run out of number
			state2 = SCE_CAML_DEFAULT, advance = false;
			break;

		case SCE_CAML_CHAR:
			if (!isSML) {
				// [try to] interpret as [additional] char literal char
				if (sc.Match('\\')) {
					chLit = 1;	// (definitely IS a char literal)
					if (sc.chPrev == '\\')
						sc.ch = ' ';	// (...\\')
				// should we be terminating - one way or another?
				} else if ((sc.Match('\'') && sc.chPrev != '\\')
					|| sc.atLineEnd) {
					state2 = SCE_CAML_DEFAULT;
					if (sc.Match('\''))
						chColor++;
					else
						sc.ChangeState(SCE_CAML_IDENTIFIER);
				// ... maybe a char literal, maybe not
				} else if (chLit < 1 && sc.currentPos - chToken >= 2)
					sc.ChangeState(SCE_CAML_IDENTIFIER), advance = false;
				break;
			}/* else
				// fall through for SML char literal (handle like string) */
			// Falls through.

		case SCE_CAML_STRING:
			// [try to] interpret as [additional] [SML char/] string literal char
			if (isSML && sc.Match('\\') && sc.chPrev != '\\' && isspace(sc.chNext))
				state2 = SCE_CAML_WHITE;
			else if (sc.Match('\\') && sc.chPrev == '\\')
				sc.ch = ' ';	// (...\\")
			// should we be terminating - one way or another?
			else if ((sc.Match('"') && sc.chPrev != '\\')
				|| (isSML && sc.atLineEnd)) {
				state2 = SCE_CAML_DEFAULT;
				if (sc.Match('"'))
					chColor++;
			}
			break;

		case SCE_CAML_WHITE:
			// [try to] interpret as [additional] SML embedded whitespace char
			if (sc.Match('\\')) {
				// style this puppy NOW...
				state2 = SCE_CAML_STRING, sc.ch = ' ' /* (...\") */, chColor++,
					styler.ColourTo(chColor, SCE_CAML_WHITE), styler.Flush();
				// ... then backtrack to determine original SML literal type
				Sci_Position p = chColor - 2;
				for (; p >= 0 && styler.StyleAt(p) == SCE_CAML_WHITE; p--) ;
				if (p >= 0)
					state2 = static_cast<int>(styler.StyleAt(p));
				// take care of state change NOW
				sc.ChangeState(state2), state2 = -1;
			}
			break;

		case SCE_CAML_COMMENT:
		case SCE_CAML_COMMENT1:
		case SCE_CAML_COMMENT2:
		case SCE_CAML_COMMENT3:
			// we're IN a comment - does this start a NESTED comment?
			if (sc.Match('(', '*'))
				state2 = sc.state + 1, chToken = sc.currentPos,
					sc.Forward(), sc.ch = ' ' /* (*)... */, nesting++;
			// [try to] interpret as [additional] comment char
			else if (sc.Match(')') && sc.chPrev == '*') {
				if (nesting)
					state2 = (sc.state & 0x0f) - 1, chToken = 0, nesting--;
				else
					state2 = SCE_CAML_DEFAULT;
				chColor++;
			// enable "magic" (read-only) comment AS REQUIRED
			} else if (useMagic && sc.currentPos - chToken == 4
				&& sc.Match('c') && sc.chPrev == 'r' && sc.GetRelative(-2) == '@')
				sc.state |= 0x10;	// (switch to read-only comment style)
			break;
		}

		// handle state change and char coloring AS REQUIRED
		if (state2 >= 0)
			styler.ColourTo(chColor, sc.state), sc.ChangeState(state2);
		// move to next char UNLESS re-scanning current char
		if (advance)
			sc.Forward();
	}

	// do any required terminal char coloring (JIC)
	sc.Complete();
}

static
void FoldCamlDoc(
	Sci_PositionU, Sci_Position,
	int,
	WordList *[],
	Accessor &)
{
}

static const char * const camlWordListDesc[] = {
	"Keywords",		// primary Objective Caml keywords
	"Keywords2",	// "optional" keywords (typically from Pervasives)
	"Keywords3",	// "optional" keywords (typically typenames)
	0
};

LexerModule lmCaml(SCLEX_CAML, ColouriseCamlDoc, "caml", FoldCamlDoc, camlWordListDesc);