src/java/org/apache/cassandra/cql3/ErrorCollector.java - cassandra - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you 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.apache.cassandra.cql3;

 import java.util.LinkedList;

 import org.antlr.runtime.BaseRecognizer;
 import org.antlr.runtime.Parser;
 import org.antlr.runtime.RecognitionException;
 import org.antlr.runtime.Token;
 import org.antlr.runtime.TokenStream;
 import org.apache.cassandra.exceptions.SyntaxException;

 /**
  * <code>ErrorListener</code> that collect and enhance the errors send by the CQL lexer and parser.
  */
 public final class ErrorCollector implements ErrorListener
 {
     /**
      * The offset of the first token of the snippet.
      */
     private static final int FIRST_TOKEN_OFFSET = 10;

     /**
      * The offset of the last token of the snippet.
      */
     private static final int LAST_TOKEN_OFFSET = 2;

     /**
      * The CQL query.
      */
     private final String query;

     /**
      * The error messages.
      */
     private final LinkedList<String> errorMsgs = new LinkedList<>();

     /**
      * Creates a new <code>ErrorCollector</code> instance to collect the syntax errors associated to the specified CQL
      * query.
      *
      * @param query the CQL query that will be parsed
      */
     public ErrorCollector(String query)
     {
         this.query = query;
     }

     /**
      * {@inheritDoc}
      */
     @Override
     public void syntaxError(BaseRecognizer recognizer, String[] tokenNames, RecognitionException e)
     {
         String hdr = recognizer.getErrorHeader(e);
         String msg = recognizer.getErrorMessage(e, tokenNames);

         StringBuilder builder = new StringBuilder().append(hdr)
                 .append(' ')
                 .append(msg);

         if (recognizer instanceof Parser)
             appendQuerySnippet((Parser) recognizer, builder);

         errorMsgs.add(builder.toString());
     }

     /**
      * {@inheritDoc}
      */
     @Override
     public void syntaxError(BaseRecognizer recognizer, String errorMsg)
     {
         errorMsgs.add(errorMsg);
     }

     /**
      * Throws the first syntax error found by the lexer or the parser if it exists.
      *
      * @throws SyntaxException the syntax error.
      */
     public void throwFirstSyntaxError() throws SyntaxException
     {
         if (!errorMsgs.isEmpty())
             throw new SyntaxException(errorMsgs.getFirst());
     }

     /**
      * Appends a query snippet to the message to help the user to understand the problem.
      *
      * @param parser the parser used to parse the query
      * @param builder the <code>StringBuilder</code> used to build the error message
      */
     private void appendQuerySnippet(Parser parser, StringBuilder builder)
     {
         TokenStream tokenStream = parser.getTokenStream();
         int index = tokenStream.index();
         int size = tokenStream.size();

         Token from = tokenStream.get(getSnippetFirstTokenIndex(index));
         Token to = tokenStream.get(getSnippetLastTokenIndex(index, size));
         Token offending = tokenStream.get(getOffendingTokenIndex(index, size));

         appendSnippet(builder, from, to, offending);
     }

     /**
      * Appends a query snippet to the message to help the user to understand the problem.
      *
      * @param from the first token to include within the snippet
      * @param to the last token to include within the snippet
      * @param offending the token which is responsible for the error
      */
     final void appendSnippet(StringBuilder builder,
                              Token from,
                              Token to,
                              Token offending)
     {
         if (!areTokensValid(from, to, offending))
             return;

         String[] lines = query.split("\n");

         boolean includeQueryStart = (from.getLine() == 1) && (from.getCharPositionInLine() == 0);
         boolean includeQueryEnd = (to.getLine() == lines.length)
                 && (getLastCharPositionInLine(to) == lines[lines.length - 1].length());

         builder.append(" (");

         if (!includeQueryStart)
             builder.append("...");

         String toLine = lines[lineIndex(to)];
         int toEnd = getLastCharPositionInLine(to);
         lines[lineIndex(to)] = toEnd >= toLine.length() ? toLine : toLine.substring(0, toEnd);
         lines[lineIndex(offending)] = highlightToken(lines[lineIndex(offending)], offending);
         lines[lineIndex(from)] = lines[lineIndex(from)].substring(from.getCharPositionInLine());

         for (int i = lineIndex(from), m = lineIndex(to); i <= m; i++)
             builder.append(lines[i]);

         if (!includeQueryEnd)
             builder.append("...");

         builder.append(")");
     }

     /**
      * Checks if the specified tokens are valid.
      *
      * @param tokens the tokens to check
      * @return <code>true</code> if all the specified tokens are valid ones,
      * <code>false</code> otherwise.
      */
     private static boolean areTokensValid(Token... tokens)
     {
         for (Token token : tokens)
         {
             if (!isTokenValid(token))
                 return false;
         }
         return true;
     }

     /**
      * Checks that the specified token is valid.
      *
      * @param token the token to check
      * @return <code>true</code> if it is considered as valid, <code>false</code> otherwise.
      */
     private static boolean isTokenValid(Token token)
     {
         return token.getLine() > 0 && token.getCharPositionInLine() >= 0;
     }

     /**
      * Returns the index of the offending token. <p>In the case where the offending token is an extra
      * character at the end, the index returned by the <code>TokenStream</code> might be after the last token.
      * To avoid that problem we need to make sure that the index of the offending token is a valid index
      * (one for which a token exist).</p>
      *
      * @param index the token index returned by the <code>TokenStream</code>
      * @param size the <code>TokenStream</code> size
      * @return the valid index of the offending token
      */
     private static int getOffendingTokenIndex(int index, int size)
     {
         return Math.min(index, size - 1);
     }

     /**
      * Puts the specified token within square brackets.
      *
      * @param line the line containing the token
      * @param token the token to put within square brackets
      */
     private static String highlightToken(String line, Token token)
     {
         String newLine = insertChar(line, getLastCharPositionInLine(token), ']');
         return insertChar(newLine, token.getCharPositionInLine(), '[');
     }

     /**
      * Returns the index of the last character relative to the beginning of the line 0..n-1
      *
      * @param token the token
      * @return the index of the last character relative to the beginning of the line 0..n-1
      */
     private static int getLastCharPositionInLine(Token token)
     {
         return token.getCharPositionInLine() + getLength(token);
     }

     /**
      * Return the token length.
      *
      * @param token the token
      * @return the token length
      */
     private static int getLength(Token token)
     {
         return token.getText().length();
     }

     /**
      * Inserts a character at a given position within a <code>String</code>.
      *
      * @param s the <code>String</code> in which the character must be inserted
      * @param index the position where the character must be inserted
      * @param c the character to insert
      * @return the modified <code>String</code>
      */
     private static String insertChar(String s, int index, char c)
     {
         return new StringBuilder().append(s.substring(0, index))
                 .append(c)
                 .append(s.substring(index))
                 .toString();
     }

     /**
      * Returns the index of the line number on which this token was matched; index=0..n-1
      *
      * @param token the token
      * @return the index of the line number on which this token was matched; index=0..n-1
      */
     private static int lineIndex(Token token)
     {
         return token.getLine() - 1;
     }

     /**
      * Returns the index of the last token which is part of the snippet.
      *
      * @param index the index of the token causing the error
      * @param size the total number of tokens
      * @return the index of the last token which is part of the snippet.
      */
     private static int getSnippetLastTokenIndex(int index, int size)
     {
         return Math.min(size - 1, index + LAST_TOKEN_OFFSET);
     }

     /**
      * Returns the index of the first token which is part of the snippet.
      *
      * @param index the index of the token causing the error
      * @return the index of the first token which is part of the snippet.
      */
     private static int getSnippetFirstTokenIndex(int index)
     {
         return Math.max(0, index - FIRST_TOKEN_OFFSET);
     }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you 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.apache.cassandra.cql3;

	import java.util.LinkedList;

	import org.antlr.runtime.BaseRecognizer;
	import org.antlr.runtime.Parser;
	import org.antlr.runtime.RecognitionException;
	import org.antlr.runtime.Token;
	import org.antlr.runtime.TokenStream;
	import org.apache.cassandra.exceptions.SyntaxException;

	/**
	* <code>ErrorListener</code> that collect and enhance the errors send by the CQL lexer and parser.
	*/
	public final class ErrorCollector implements ErrorListener
	{
	/**
	* The offset of the first token of the snippet.
	*/
	private static final int FIRST_TOKEN_OFFSET = 10;

	/**
	* The offset of the last token of the snippet.
	*/
	private static final int LAST_TOKEN_OFFSET = 2;

	/**
	* The CQL query.
	*/
	private final String query;

	/**
	* The error messages.
	*/
	private final LinkedList<String> errorMsgs = new LinkedList<>();

	/**
	* Creates a new <code>ErrorCollector</code> instance to collect the syntax errors associated to the specified CQL
	* query.
	*
	* @param query the CQL query that will be parsed
	*/
	public ErrorCollector(String query)
	{
	this.query = query;
	}

	/**
	* {@inheritDoc}
	*/
	@Override
	public void syntaxError(BaseRecognizer recognizer, String[] tokenNames, RecognitionException e)
	{
	String hdr = recognizer.getErrorHeader(e);
	String msg = recognizer.getErrorMessage(e, tokenNames);

	StringBuilder builder = new StringBuilder().append(hdr)
	.append(' ')
	.append(msg);

	if (recognizer instanceof Parser)
	appendQuerySnippet((Parser) recognizer, builder);

	errorMsgs.add(builder.toString());
	}

	/**
	* {@inheritDoc}
	*/
	@Override
	public void syntaxError(BaseRecognizer recognizer, String errorMsg)
	{
	errorMsgs.add(errorMsg);
	}

	/**
	* Throws the first syntax error found by the lexer or the parser if it exists.
	*
	* @throws SyntaxException the syntax error.
	*/
	public void throwFirstSyntaxError() throws SyntaxException
	{
	if (!errorMsgs.isEmpty())
	throw new SyntaxException(errorMsgs.getFirst());
	}

	/**
	* Appends a query snippet to the message to help the user to understand the problem.
	*
	* @param parser the parser used to parse the query
	* @param builder the <code>StringBuilder</code> used to build the error message
	*/
	private void appendQuerySnippet(Parser parser, StringBuilder builder)
	{
	TokenStream tokenStream = parser.getTokenStream();
	int index = tokenStream.index();
	int size = tokenStream.size();

	Token from = tokenStream.get(getSnippetFirstTokenIndex(index));
	Token to = tokenStream.get(getSnippetLastTokenIndex(index, size));
	Token offending = tokenStream.get(getOffendingTokenIndex(index, size));

	appendSnippet(builder, from, to, offending);
	}

	/**
	* Appends a query snippet to the message to help the user to understand the problem.
	*
	* @param from the first token to include within the snippet
	* @param to the last token to include within the snippet
	* @param offending the token which is responsible for the error
	*/
	final void appendSnippet(StringBuilder builder,
	Token from,
	Token to,
	Token offending)
	{
	if (!areTokensValid(from, to, offending))
	return;

	String[] lines = query.split("\n");

	boolean includeQueryStart = (from.getLine() == 1) && (from.getCharPositionInLine() == 0);
	boolean includeQueryEnd = (to.getLine() == lines.length)
	&& (getLastCharPositionInLine(to) == lines[lines.length - 1].length());

	builder.append(" (");

	if (!includeQueryStart)
	builder.append("...");

	String toLine = lines[lineIndex(to)];
	int toEnd = getLastCharPositionInLine(to);
	lines[lineIndex(to)] = toEnd >= toLine.length() ? toLine : toLine.substring(0, toEnd);
	lines[lineIndex(offending)] = highlightToken(lines[lineIndex(offending)], offending);
	lines[lineIndex(from)] = lines[lineIndex(from)].substring(from.getCharPositionInLine());

	for (int i = lineIndex(from), m = lineIndex(to); i <= m; i++)
	builder.append(lines[i]);

	if (!includeQueryEnd)
	builder.append("...");

	builder.append(")");
	}

	/**
	* Checks if the specified tokens are valid.
	*
	* @param tokens the tokens to check
	* @return <code>true</code> if all the specified tokens are valid ones,
	* <code>false</code> otherwise.
	*/
	private static boolean areTokensValid(Token... tokens)
	{
	for (Token token : tokens)
	{
	if (!isTokenValid(token))
	return false;
	}
	return true;
	}

	/**
	* Checks that the specified token is valid.
	*
	* @param token the token to check
	* @return <code>true</code> if it is considered as valid, <code>false</code> otherwise.
	*/
	private static boolean isTokenValid(Token token)
	{
	return token.getLine() > 0 && token.getCharPositionInLine() >= 0;
	}

	/**
	* Returns the index of the offending token. <p>In the case where the offending token is an extra
	* character at the end, the index returned by the <code>TokenStream</code> might be after the last token.
	* To avoid that problem we need to make sure that the index of the offending token is a valid index
	* (one for which a token exist).</p>
	*
	* @param index the token index returned by the <code>TokenStream</code>
	* @param size the <code>TokenStream</code> size
	* @return the valid index of the offending token
	*/
	private static int getOffendingTokenIndex(int index, int size)
	{
	return Math.min(index, size - 1);
	}

	/**
	* Puts the specified token within square brackets.
	*
	* @param line the line containing the token
	* @param token the token to put within square brackets
	*/
	private static String highlightToken(String line, Token token)
	{
	String newLine = insertChar(line, getLastCharPositionInLine(token), ']');
	return insertChar(newLine, token.getCharPositionInLine(), '[');
	}

	/**
	* Returns the index of the last character relative to the beginning of the line 0..n-1
	*
	* @param token the token
	* @return the index of the last character relative to the beginning of the line 0..n-1
	*/
	private static int getLastCharPositionInLine(Token token)
	{
	return token.getCharPositionInLine() + getLength(token);
	}

	/**
	* Return the token length.
	*
	* @param token the token
	* @return the token length
	*/
	private static int getLength(Token token)
	{
	return token.getText().length();
	}

	/**
	* Inserts a character at a given position within a <code>String</code>.
	*
	* @param s the <code>String</code> in which the character must be inserted
	* @param index the position where the character must be inserted
	* @param c the character to insert
	* @return the modified <code>String</code>
	*/
	private static String insertChar(String s, int index, char c)
	{
	return new StringBuilder().append(s.substring(0, index))
	.append(c)
	.append(s.substring(index))
	.toString();
	}

	/**
	* Returns the index of the line number on which this token was matched; index=0..n-1
	*
	* @param token the token
	* @return the index of the line number on which this token was matched; index=0..n-1
	*/
	private static int lineIndex(Token token)
	{
	return token.getLine() - 1;
	}

	/**
	* Returns the index of the last token which is part of the snippet.
	*
	* @param index the index of the token causing the error
	* @param size the total number of tokens
	* @return the index of the last token which is part of the snippet.
	*/
	private static int getSnippetLastTokenIndex(int index, int size)
	{
	return Math.min(size - 1, index + LAST_TOKEN_OFFSET);
	}

	/**
	* Returns the index of the first token which is part of the snippet.
	*
	* @param index the index of the token causing the error
	* @return the index of the first token which is part of the snippet.
	*/
	private static int getSnippetFirstTokenIndex(int index)
	{
	return Math.max(0, index - FIRST_TOKEN_OFFSET);
	}
	}