/*

 * Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.tools.javac.parser;

import com.sun.tools.javac.code.Preview;

import com.sun.tools.javac.code.Source;

import com.sun.tools.javac.code.Source.Feature;

import com.sun.tools.javac.parser.Tokens.Comment.CommentStyle;

import com.sun.tools.javac.resources.CompilerProperties.Errors;

import com.sun.tools.javac.util.*;

import com.sun.tools.javac.util.JCDiagnostic.DiagnosticFlag;

import java.nio.CharBuffer;

import static com.sun.tools.javac.parser.Tokens.*;

import static com.sun.tools.javac.util.LayoutCharacters.*;

/** The lexical analyzer maps an input stream consisting of

 *  ASCII characters and Unicode escapes into a token sequence.

 *

 *  <p><b>This is NOT part of any supported API.

 *  If you write code that depends on this, you do so at your own risk.

 *  This code and its internal interfaces are subject to change or

 *  deletion without notice.</b>

 */

public class JavaTokenizer {

    private static final boolean scannerDebug = false;

    /** The source language setting.

     */

    private Source source;

    /** The preview language setting. */

    private Preview preview;

    /** The log to be used for error reporting.

     */

    private final Log log;

    /** The token factory. */

    private final Tokens tokens;

    /** The token kind, set by nextToken().

     */

    protected TokenKind tk;

    /** The token's radix, set by nextToken().

     */

    protected int radix;

    /** The token's name, set by nextToken().

     */

    protected Name name;

    /** The position where a lexical error occurred;

     */

    protected int errPos = Position.NOPOS;

    /** The Unicode reader (low-level stream reader).

     */

    protected UnicodeReader reader;

    protected ScannerFactory fac;

    private static final boolean hexFloatsWork = hexFloatsWork();

    private static boolean hexFloatsWork() {

        try {

            Float.valueOf("0x1.0p1");

            return true;

        } catch (NumberFormatException ex) {

            return false;

        }

    }

    /**

     * Create a scanner from the input array.  This method might

     * modify the array.  To avoid copying the input array, ensure

     * that {@code inputLength < input.length} or

     * {@code input[input.length -1]} is a white space character.

     *

     * @param fac the factory which created this Scanner

     * @param buf the input, might be modified

     * Must be positive and less than or equal to input.length.

     */

    protected JavaTokenizer(ScannerFactory fac, CharBuffer buf) {

        this(fac, new UnicodeReader(fac, buf));

    }

    protected JavaTokenizer(ScannerFactory fac, char[] buf, int inputLength) {

        this(fac, new UnicodeReader(fac, buf, inputLength));

    }

    protected JavaTokenizer(ScannerFactory fac, UnicodeReader reader) {

        this.fac = fac;

        this.log = fac.log;

        this.tokens = fac.tokens;

        this.source = fac.source;

        this.preview = fac.preview;

        this.reader = reader;

    }

    protected void checkSourceLevel(int pos, Feature feature) {

        if (preview.isPreview(feature) && !preview.isEnabled()) {

            //preview feature without --preview flag, error

            lexError(DiagnosticFlag.SOURCE_LEVEL, pos, preview.disabledError(feature));

        } else if (!feature.allowedInSource(source)) {

            //incompatible source level, error

            lexError(DiagnosticFlag.SOURCE_LEVEL, pos, feature.error(source.name));

        } else if (preview.isPreview(feature)) {

            //use of preview feature, warn

            preview.warnPreview(pos, feature);

        }

    }

    /** Report an error at the given position using the provided arguments.

     */

    protected void lexError(int pos, JCDiagnostic.Error key) {

        log.error(pos, key);

        tk = TokenKind.ERROR;

        errPos = pos;

    }

    protected void lexError(DiagnosticFlag flags, int pos, JCDiagnostic.Error key) {

        log.error(flags, pos, key);

        tk = TokenKind.ERROR;

        errPos = pos;

    }

    /** Read next character in character or string literal and copy into sbuf.

     */

    private void scanLitChar(int pos) {

        if (reader.ch == '\\') {

            if (reader.peekChar() == '\\' && !reader.isUnicode()) {

                reader.skipChar();

                reader.putChar('\\', true);

            } else {

                reader.scanChar();

                switch (reader.ch) {

                case '0': case '1': case '2': case '3':

                case '4': case '5': case '6': case '7':

                    char leadch = reader.ch;

                    int oct = reader.digit(pos, 8);

                    reader.scanChar();

                    if ('0' <= reader.ch && reader.ch <= '7') {

                        oct = oct * 8 + reader.digit(pos, 8);

                        reader.scanChar();

                        if (leadch <= '3' && '0' <= reader.ch && reader.ch <= '7') {

                            oct = oct * 8 + reader.digit(pos, 8);

                            reader.scanChar();

                        }

                    }

                    reader.putChar((char)oct);

                    break;

                case 'b':

                    reader.putChar('\b', true); break;

                case 't':

                    reader.putChar('\t', true); break;

                case 'n':

                    reader.putChar('\n', true); break;

                case 'f':

                    reader.putChar('\f', true); break;

                case 'r':

                    reader.putChar('\r', true); break;

                case '\'':

                    reader.putChar('\'', true); break;

                case '\"':

                    reader.putChar('\"', true); break;

                case '\\':

                    reader.putChar('\\', true); break;

                default:

                    lexError(reader.bp, Errors.IllegalEscChar);

                }

            }

        } else if (reader.bp != reader.buflen) {

            reader.putChar(true);

        }

    }

    private void scanDigits(int pos, int digitRadix) {

        char saveCh;

        int savePos;

        do {

            if (reader.ch != '_') {

                reader.putChar(false);

            }

            saveCh = reader.ch;

            savePos = reader.bp;

            reader.scanChar();

        } while (reader.digit(pos, digitRadix) >= 0 || reader.ch == '_');

        if (saveCh == '_')

            lexError(savePos, Errors.IllegalUnderscore);

    }

    /** Read fractional part of hexadecimal floating point number.

     */

    private void scanHexExponentAndSuffix(int pos) {

        if (reader.ch == 'p' || reader.ch == 'P') {

            reader.putChar(true);

            skipIllegalUnderscores();

            if (reader.ch == '+' || reader.ch == '-') {

                reader.putChar(true);

            }

            skipIllegalUnderscores();

            if (reader.digit(pos, 10) >= 0) {

                scanDigits(pos, 10);

                if (!hexFloatsWork)

                    lexError(pos, Errors.UnsupportedCrossFpLit);

            } else

                lexError(pos, Errors.MalformedFpLit);

        } else {

            lexError(pos, Errors.MalformedFpLit);

        }

        if (reader.ch == 'f' || reader.ch == 'F') {

            reader.putChar(true);

            tk = TokenKind.FLOATLITERAL;

            radix = 16;

        } else {

            if (reader.ch == 'd' || reader.ch == 'D') {

                reader.putChar(true);

            }

            tk = TokenKind.DOUBLELITERAL;

            radix = 16;

        }

    }

    /** Read fractional part of floating point number.

     */

    private void scanFraction(int pos) {

        skipIllegalUnderscores();

        if (reader.digit(pos, 10) >= 0) {

            scanDigits(pos, 10);

        }

        int sp1 = reader.sp;

        if (reader.ch == 'e' || reader.ch == 'E') {

            reader.putChar(true);

            skipIllegalUnderscores();

            if (reader.ch == '+' || reader.ch == '-') {

                reader.putChar(true);

            }

            skipIllegalUnderscores();

            if (reader.digit(pos, 10) >= 0) {

                scanDigits(pos, 10);

                return;

            }

            lexError(pos, Errors.MalformedFpLit);

            reader.sp = sp1;

        }

    }

    /** Read fractional part and 'd' or 'f' suffix of floating point number.

     */

    private void scanFractionAndSuffix(int pos) {

        radix = 10;

        scanFraction(pos);

        if (reader.ch == 'f' || reader.ch == 'F') {

            reader.putChar(true);

            tk = TokenKind.FLOATLITERAL;

        } else {

            if (reader.ch == 'd' || reader.ch == 'D') {

                reader.putChar(true);

            }

            tk = TokenKind.DOUBLELITERAL;

        }

    }

    /** Read fractional part and 'd' or 'f' suffix of floating point number.

     */

    private void scanHexFractionAndSuffix(int pos, boolean seendigit) {

        radix = 16;

        Assert.check(reader.ch == '.');

        reader.putChar(true);

        skipIllegalUnderscores();

        if (reader.digit(pos, 16) >= 0) {

            seendigit = true;

            scanDigits(pos, 16);

        }

        if (!seendigit)

            lexError(pos, Errors.InvalidHexNumber);

        else

            scanHexExponentAndSuffix(pos);

    }

    private void skipIllegalUnderscores() {

        if (reader.ch == '_') {

            lexError(reader.bp, Errors.IllegalUnderscore);

            while (reader.ch == '_')

                reader.scanChar();

        }

    }

    /** Read a number.

     *  @param radix  The radix of the number; one of 2, 8, 10, 16.

     */

    private void scanNumber(int pos, int radix) {

        // for octal, allow base-10 digit in case it's a float literal

        this.radix = radix;

        int digitRadix = (radix == 8 ? 10 : radix);

        int firstDigit = reader.digit(pos, Math.max(10, digitRadix));

        boolean seendigit = firstDigit >= 0;

        boolean seenValidDigit = firstDigit >= 0 && firstDigit < digitRadix;

        if (seendigit) {

            scanDigits(pos, digitRadix);

        }

        if (radix == 16 && reader.ch == '.') {

            scanHexFractionAndSuffix(pos, seendigit);

        } else if (seendigit && radix == 16 && (reader.ch == 'p' || reader.ch == 'P')) {

            scanHexExponentAndSuffix(pos);

        } else if (digitRadix == 10 && reader.ch == '.') {

            reader.putChar(true);

            scanFractionAndSuffix(pos);

        } else if (digitRadix == 10 &&

                   (reader.ch == 'e' || reader.ch == 'E' ||

                    reader.ch == 'f' || reader.ch == 'F' ||

                    reader.ch == 'd' || reader.ch == 'D')) {

            scanFractionAndSuffix(pos);

        } else {

            if (!seenValidDigit) {

                switch (radix) {

                case 2:

                    lexError(pos, Errors.InvalidBinaryNumber);

                    break;

                case 16:

                    lexError(pos, Errors.InvalidHexNumber);

                    break;

                }

            }

            if (reader.ch == 'l' || reader.ch == 'L') {

                reader.scanChar();

                tk = TokenKind.LONGLITERAL;

            } else {

                tk = TokenKind.INTLITERAL;

            }

        }

    }

    /** Read an identifier.

     */

    private void scanIdent() {

        boolean isJavaIdentifierPart;

        char high;

        reader.putChar(true);

        do {

            switch (reader.ch) {

            case 'A': case 'B': case 'C': case 'D': case 'E':

            case 'F': case 'G': case 'H': case 'I': case 'J':

            case 'K': case 'L': case 'M': case 'N': case 'O':

            case 'P': case 'Q': case 'R': case 'S': case 'T':

            case 'U': case 'V': case 'W': case 'X': case 'Y':

            case 'Z':

            case 'a': case 'b': case 'c': case 'd': case 'e':

            case 'f': case 'g': case 'h': case 'i': case 'j':

            case 'k': case 'l': case 'm': case 'n': case 'o':

            case 'p': case 'q': case 'r': case 's': case 't':

            case 'u': case 'v': case 'w': case 'x': case 'y':

            case 'z':

            case '$': case '_':

            case '0': case '1': case '2': case '3': case '4':

            case '5': case '6': case '7': case '8': case '9':

                break;

            case '\u0000': case '\u0001': case '\u0002': case '\u0003':

            case '\u0004': case '\u0005': case '\u0006': case '\u0007':

            case '\u0008': case '\u000E': case '\u000F': case '\u0010':

            case '\u0011': case '\u0012': case '\u0013': case '\u0014':

            case '\u0015': case '\u0016': case '\u0017':

            case '\u0018': case '\u0019': case '\u001B':

            case '\u007F':

                reader.scanChar();

                continue;

            case '\u001A': // EOI is also a legal identifier part

                if (reader.bp >= reader.buflen) {

                    name = reader.name();

                    tk = tokens.lookupKind(name);

                    return;

                }

                reader.scanChar();

                continue;

            default:

                if (reader.ch < '\u0080') {

                    // all ASCII range chars already handled, above

                    isJavaIdentifierPart = false;

                } else {

                    if (Character.isIdentifierIgnorable(reader.ch)) {

                        reader.scanChar();

                        continue;

                    } else {

                        int codePoint = reader.peekSurrogates();

                        if (codePoint >= 0) {

                            if (isJavaIdentifierPart = Character.isJavaIdentifierPart(codePoint)) {

                                reader.putChar(true);

                            }

                        } else {

                            isJavaIdentifierPart = Character.isJavaIdentifierPart(reader.ch);

                        }

                    }

                }

                if (!isJavaIdentifierPart) {

                    name = reader.name();

                    tk = tokens.lookupKind(name);

                    return;

                }

            }

            reader.putChar(true);

        } while (true);

    }

    /** Return true if reader.ch can be part of an operator.

     */

    private boolean isSpecial(char ch) {

        switch (ch) {

        case '!': case '%': case '&': case '*': case '?':

        case '+': case '-': case ':': case '<': case '=':

        case '>': case '^': case '|': case '~':

        case '@':

            return true;

        default:

            return false;

        }

    }

    /** Read longest possible sequence of special characters and convert

     *  to token.

     */

    private void scanOperator() {

        while (true) {

            reader.putChar(false);

            Name newname = reader.name();

            TokenKind tk1 = tokens.lookupKind(newname);

            if (tk1 == TokenKind.IDENTIFIER) {

                reader.sp--;

                break;

            }

            tk = tk1;

            reader.scanChar();

            if (!isSpecial(reader.ch)) break;

        }

    }

    /** Read token.

     */

    public Token readToken() {

        reader.sp = 0;

        name = null;

        radix = 0;

        int pos = 0;

        int endPos = 0;

        List<Comment> comments = null;

        try {

            loop: while (true) {

                pos = reader.bp;

                switch (reader.ch) {

                case ' ': // (Spec 3.6)

                case '\t': // (Spec 3.6)

                case FF: // (Spec 3.6)

                    do {

                        reader.scanChar();

                    } while (reader.ch == ' ' || reader.ch == '\t' || reader.ch == FF);

                    processWhiteSpace(pos, reader.bp);

                    break;

                case LF: // (Spec 3.4)

                    reader.scanChar();

                    processLineTerminator(pos, reader.bp);

                    break;

                case CR: // (Spec 3.4)

                    reader.scanChar();

                    if (reader.ch == LF) {

                        reader.scanChar();

                    }

                    processLineTerminator(pos, reader.bp);

                    break;

                case 'A': case 'B': case 'C': case 'D': case 'E':

                case 'F': case 'G': case 'H': case 'I': case 'J':

                case 'K': case 'L': case 'M': case 'N': case 'O':

                case 'P': case 'Q': case 'R': case 'S': case 'T':

                case 'U': case 'V': case 'W': case 'X': case 'Y':

                case 'Z':

                case 'a': case 'b': case 'c': case 'd': case 'e':

                case 'f': case 'g': case 'h': case 'i': case 'j':

                case 'k': case 'l': case 'm': case 'n': case 'o':

                case 'p': case 'q': case 'r': case 's': case 't':

                case 'u': case 'v': case 'w': case 'x': case 'y':

                case 'z':

                case '$': case '_':

                    scanIdent();

                    break loop;