RegExpSupport/src/org/intellij/lang/regexp/psi/impl/RegExpCharImpl.java

/*
 * Copyright 2006 Sascha Weinreuter
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.intellij.lang.regexp.psi.impl;

import com.intellij.lang.ASTNode;
import com.intellij.psi.StringEscapesTokenTypes;
import com.intellij.psi.TokenType;
import com.intellij.psi.tree.IElementType;
import com.intellij.psi.tree.TokenSet;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import org.intellij.lang.regexp.RegExpTT;
import org.intellij.lang.regexp.psi.RegExpChar;
import org.intellij.lang.regexp.psi.RegExpElementVisitor;

public class RegExpCharImpl extends RegExpElementImpl implements RegExpChar {
    private static final TokenSet OCT_CHARS = TokenSet.create(RegExpTT.OCT_CHAR, RegExpTT.BAD_OCT_VALUE);
    private static final TokenSet HEX_CHARS = TokenSet.create(RegExpTT.HEX_CHAR, RegExpTT.BAD_HEX_VALUE);
    private static final TokenSet UNICODE_CHARS = TokenSet.create(RegExpTT.HEX_CHAR, StringEscapesTokenTypes.INVALID_UNICODE_ESCAPE_TOKEN);

    public RegExpCharImpl(ASTNode astNode) {
        super(astNode);
    }

    @NotNull
    public Type getType() {
        final ASTNode child = getNode().getFirstChildNode();
        assert child != null;
        final IElementType t = child.getElementType();
        if (OCT_CHARS.contains(t)) {
            return Type.OCT;
        } else if (HEX_CHARS.contains(t)) {
            return Type.HEX;
        } else if (UNICODE_CHARS.contains(t)) {
            return Type.UNICODE;
        } else if (t == TokenType.ERROR_ELEMENT) {
            return Type.INVALID;
        } else {
            return Type.CHAR;
        }
    }

    @Nullable
    public Character getValue() {
      final String s = getUnescapedText();
      if (s.equals("\\") && getType() == Type.CHAR) {
        return '\\';
      }
      // special case for valid octal escaped sequences (see RUBY-12161)
      if (s.startsWith("\\") && s.length() > 1) {
        final ASTNode child = getNode().getFirstChildNode();
        assert child != null;
        final IElementType t = child.getElementType();
        if (t == RegExpTT.OCT_CHAR) {
          try {
            return (char) Integer.parseInt(s.substring(1), 8);
          }
          catch (NumberFormatException e) {
            // do nothing
          }
        } else {
          char nextChar = s.charAt(1);
          if (Character.isDigit(nextChar) && nextChar != '0') {
            Character character = parseNumber(0, s, 10, s.length() - 1, true);
            if (character != null) {
              return character;
            }
          }
        }
      }
      return unescapeChar(s);
    }

    @Nullable
    static Character unescapeChar(String s) {
        assert s.length() > 0;

        boolean escaped = false;
        for (int idx = 0; idx < s.length(); idx++) {
            char ch = s.charAt(idx);
            if (!escaped) {
                if (ch == '\\') {
                    escaped = true;
                } else {
                    return ch;
                }
            } else {
                switch (ch) {
                    case'n':
                        return '\n';
                    case'r':
                        return '\r';
                    case't':
                        return '\t';
                    case'a':
                        return '\u0007';
                    case'e':
                        return '\u001b';
                    case'f':
                        return '\f';
                    case 'b':
                        return '\b';
                    case'c':
                        return (char)(ch ^ 64);
                    case'x':
                        return parseNumber(idx, s, 16, 2, true);
                    case'u':
                        return parseNumber(idx, s, 16, 4, true);
                    case'0':
                        return parseNumber(idx, s, 8, 3, false);
                    default:
                        if (Character.isLetter(ch)) {
                            return null;
                        }
                        return ch;
                }
            }
        }

        return null;
    }

    static Character parseNumber(int idx, String s, int radix, int len, boolean strict) {
        final int start = idx + 1;
        final int end = start + len;
        try {
            int sum = 0;
            int i;
            for (i = start; i < end && i < s.length(); i++) {
                sum *= radix;
                sum += Integer.valueOf(s.substring(i, i + 1), radix);
            }
            if (i-start == 0) return null;
            return i-start < len && strict ? null : (char)sum;
        } catch (NumberFormatException e1) {
            return null;
        }
    }

    public void accept(RegExpElementVisitor visitor) {
        visitor.visitRegExpChar(this);
    }
}