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/*
* 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.drill.exec.record.metadata.schema.parser;
import org.antlr.v4.runtime.BaseErrorListener;
import org.antlr.v4.runtime.CharStreams;
import org.antlr.v4.runtime.CodePointCharStream;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.RecognitionException;
import org.antlr.v4.runtime.Recognizer;
import org.apache.drill.exec.record.metadata.ColumnMetadata;
import org.apache.drill.exec.record.metadata.TupleMetadata;
public class SchemaExprParser {
/**
* Parses string definition of the schema and converts it
* into {@link TupleMetadata} instance.
*
* @param schema schema definition
* @return metadata description of the schema
*/
public static TupleMetadata parseSchema(String schema) {
SchemaVisitor visitor = new SchemaVisitor();
return visitor.visit(initParser(schema).schema());
}
/**
* Parses string definition of the column and converts it
* into {@link ColumnMetadata} instance.
*
* @param column column definition
* @return metadata description of the column
*/
public static ColumnMetadata parseColumn(String column) {
SchemaVisitor.ColumnVisitor visitor = new SchemaVisitor.ColumnVisitor();
return visitor.visit(initParser(column).column());
}
private static SchemaParser initParser(String value) {
CodePointCharStream stream = CharStreams.fromString(value);
UpperCaseCharStream upperCaseStream = new UpperCaseCharStream(stream);
SchemaLexer lexer = new SchemaLexer(upperCaseStream);
lexer.removeErrorListeners();
lexer.addErrorListener(ErrorListener.INSTANCE);
CommonTokenStream tokens = new CommonTokenStream(lexer);
SchemaParser parser = new SchemaParser(tokens);
parser.removeErrorListeners();
parser.addErrorListener(ErrorListener.INSTANCE);
return parser;
}
/**
* Custom error listener that converts all syntax errors into {@link SchemaParsingException}.
*/
private static class ErrorListener extends BaseErrorListener {
static final ErrorListener INSTANCE = new ErrorListener();
@Override
public void syntaxError(Recognizer<?, ?> recognizer, Object offendingSymbol, int line,
int charPositionInLine, String msg, RecognitionException e) {
StringBuilder builder = new StringBuilder();
builder.append("Line [").append(line).append("]");
builder.append(", position [").append(charPositionInLine).append("]");
if (offendingSymbol != null) {
builder.append(", offending symbol ").append(offendingSymbol);
}
if (msg != null) {
builder.append(": ").append(msg);
}
throw new SchemaParsingException(builder.toString());
}
}
}
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