org.apache.hadoop.hive.ql.parse.ParseDriver Maven / Gradle / Ivy
/**
* 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.hadoop.hive.ql.parse;
import java.util.ArrayList;
import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.CharStream;
import org.antlr.runtime.NoViableAltException;
import org.antlr.runtime.RecognitionException;
import org.antlr.runtime.Token;
import org.antlr.runtime.TokenRewriteStream;
import org.antlr.runtime.TokenStream;
import org.antlr.runtime.tree.CommonTree;
import org.antlr.runtime.tree.CommonTreeAdaptor;
import org.antlr.runtime.tree.TreeAdaptor;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.ql.Context;
/**
* ParseDriver.
*
*/
public class ParseDriver {
private static final Log LOG = LogFactory.getLog("hive.ql.parse.ParseDriver");
/**
* ANTLRNoCaseStringStream.
*
*/
//This class provides and implementation for a case insensitive token checker
//for the lexical analysis part of antlr. By converting the token stream into
//upper case at the time when lexical rules are checked, this class ensures that the
//lexical rules need to just match the token with upper case letters as opposed to
//combination of upper case and lower case characteres. This is purely used for matching lexical
//rules. The actual token text is stored in the same way as the user input without
//actually converting it into an upper case. The token values are generated by the consume()
//function of the super class ANTLRStringStream. The LA() function is the lookahead funtion
//and is purely used for matching lexical rules. This also means that the grammar will only
//accept capitalized tokens in case it is run from other tools like antlrworks which
//do not have the ANTLRNoCaseStringStream implementation.
public class ANTLRNoCaseStringStream extends ANTLRStringStream {
public ANTLRNoCaseStringStream(String input) {
super(input);
}
@Override
public int LA(int i) {
int returnChar = super.LA(i);
if (returnChar == CharStream.EOF) {
return returnChar;
} else if (returnChar == 0) {
return returnChar;
}
return Character.toUpperCase((char) returnChar);
}
}
/**
* HiveLexerX.
*
*/
public class HiveLexerX extends HiveLexer {
private final ArrayList errors;
public HiveLexerX() {
super();
errors = new ArrayList();
}
public HiveLexerX(CharStream input) {
super(input);
errors = new ArrayList();
}
@Override
public void displayRecognitionError(String[] tokenNames,
RecognitionException e) {
errors.add(new ParseError(this, e, tokenNames));
}
@Override
public String getErrorMessage(RecognitionException e, String[] tokenNames) {
String msg = null;
if (e instanceof NoViableAltException) {
@SuppressWarnings("unused")
NoViableAltException nvae = (NoViableAltException) e;
// for development, can add
// "decision=<<"+nvae.grammarDecisionDescription+">>"
// and "(decision="+nvae.decisionNumber+") and
// "state "+nvae.stateNumber
msg = "character " + getCharErrorDisplay(e.c) + " not supported here";
} else {
msg = super.getErrorMessage(e, tokenNames);
}
return msg;
}
public ArrayList getErrors() {
return errors;
}
}
/**
* Tree adaptor for making antlr return ASTNodes instead of CommonTree nodes
* so that the graph walking algorithms and the rules framework defined in
* ql.lib can be used with the AST Nodes.
*/
public static final TreeAdaptor adaptor = new CommonTreeAdaptor() {
/**
* Creates an ASTNode for the given token. The ASTNode is a wrapper around
* antlr's CommonTree class that implements the Node interface.
*
* @param payload
* The token.
* @return Object (which is actually an ASTNode) for the token.
*/
@Override
public Object create(Token payload) {
return new ASTNode(payload);
}
@Override
public Object dupNode(Object t) {
return create(((CommonTree)t).token);
};
@Override
public Object errorNode(TokenStream input, Token start, Token stop, RecognitionException e) {
return new ASTErrorNode(input, start, stop, e);
};
};
public ASTNode parse(String command) throws ParseException {
return parse(command, null);
}
public ASTNode parse(String command, Context ctx)
throws ParseException {
return parse(command, ctx, true);
}
/**
* Parses a command, optionally assigning the parser's token stream to the
* given context.
*
* @param command
* command to parse
*
* @param ctx
* context with which to associate this parser's token stream, or
* null if either no context is available or the context already has
* an existing stream
*
* @return parsed AST
*/
public ASTNode parse(String command, Context ctx, boolean setTokenRewriteStream)
throws ParseException {
LOG.info("Parsing command: " + command);
HiveLexerX lexer = new HiveLexerX(new ANTLRNoCaseStringStream(command));
TokenRewriteStream tokens = new TokenRewriteStream(lexer);
if (ctx != null) {
if ( setTokenRewriteStream) {
ctx.setTokenRewriteStream(tokens);
}
lexer.setHiveConf(ctx.getConf());
}
HiveParser parser = new HiveParser(tokens);
parser.setTreeAdaptor(adaptor);
HiveParser.statement_return r = null;
try {
r = parser.statement();
} catch (RecognitionException e) {
e.printStackTrace();
throw new ParseException(parser.errors);
}
if (lexer.getErrors().size() == 0 && parser.errors.size() == 0) {
LOG.info("Parse Completed");
} else if (lexer.getErrors().size() != 0) {
throw new ParseException(lexer.getErrors());
} else {
throw new ParseException(parser.errors);
}
ASTNode tree = (ASTNode) r.getTree();
tree.setUnknownTokenBoundaries();
return tree;
}
/*
* parse a String as a Select List. This allows table functions to be passed expression Strings
* that are translated in
* the context they define at invocation time. Currently used by NPath to allow users to specify
* what output they want.
* NPath allows expressions n 'tpath' a column that represents the matched set of rows. This
* column doesn't exist in
* the input schema and hence the Result Expression cannot be analyzed by the regular Hive
* translation process.
*/
public ASTNode parseSelect(String command, Context ctx) throws ParseException {
LOG.info("Parsing command: " + command);
HiveLexerX lexer = new HiveLexerX(new ANTLRNoCaseStringStream(command));
TokenRewriteStream tokens = new TokenRewriteStream(lexer);
if (ctx != null) {
ctx.setTokenRewriteStream(tokens);
}
HiveParser parser = new HiveParser(tokens);
parser.setTreeAdaptor(adaptor);
HiveParser_SelectClauseParser.selectClause_return r = null;
try {
r = parser.selectClause();
} catch (RecognitionException e) {
e.printStackTrace();
throw new ParseException(parser.errors);
}
if (lexer.getErrors().size() == 0 && parser.errors.size() == 0) {
LOG.info("Parse Completed");
} else if (lexer.getErrors().size() != 0) {
throw new ParseException(lexer.getErrors());
} else {
throw new ParseException(parser.errors);
}
return (ASTNode) r.getTree();
}
}