[ONOS-3878, 3876, 3879] Yang Parser Manager with Stack and Error Validation
Change-Id: I10e68bd676eca4d576de1234fbb67026c7b49939
diff --git a/src/main/java/org/onosproject/yangutils/parser/impl/YangUtilsParserManager.java b/src/main/java/org/onosproject/yangutils/parser/impl/YangUtilsParserManager.java
new file mode 100644
index 0000000..0878191
--- /dev/null
+++ b/src/main/java/org/onosproject/yangutils/parser/impl/YangUtilsParserManager.java
@@ -0,0 +1,110 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.onosproject.yangutils.parser.impl;
+
+import org.antlr.v4.runtime.ANTLRFileStream;
+import org.antlr.v4.runtime.ANTLRInputStream;
+import org.antlr.v4.runtime.CommonTokenStream;
+import org.antlr.v4.runtime.tree.ParseTree;
+import org.antlr.v4.runtime.tree.ParseTreeWalker;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.parser.YangUtilsParser;
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangLexer;
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.parserutils.ParseTreeErrorListener;
+
+import java.io.IOException;
+
+/**
+ * Manages file parsing, parse tree creation and data model tree creation
+ * corresponding to an input YANG file.
+ */
+public class YangUtilsParserManager implements YangUtilsParser {
+
+ @Override
+ public YangNode getDataModel(String yangFile) throws IOException, ParserException {
+
+ /**
+ * Create a char stream that reads from YANG file. Throws an exception
+ * in case input YANG file is either null or non existent.
+ */
+ ANTLRInputStream input = null;
+ try {
+ input = new ANTLRFileStream(yangFile);
+ } catch (IOException e) {
+ e.printStackTrace();
+ throw e;
+ }
+
+ // Create a lexer that feeds off of input char stream.
+ GeneratedYangLexer lexer = new GeneratedYangLexer(input);
+
+ // Create a buffer of tokens pulled from the lexer.
+ CommonTokenStream tokens = new CommonTokenStream(lexer);
+
+ // Create a parser that feeds off the tokens buffer.
+ GeneratedYangParser parser = new GeneratedYangParser(tokens);
+
+ // Remove console error listener.
+ parser.removeErrorListeners();
+
+ // Create instance of customized error listener.
+ ParseTreeErrorListener parseTreeErrorListener = new ParseTreeErrorListener();
+
+ // Add customized error listener to catch errors during parsing.
+ parser.addErrorListener(parseTreeErrorListener);
+
+ // Begin parsing YANG file and generate parse tree.
+ ParseTree tree = parser.yangfile();
+
+ /**
+ * Throws an parser Exception if exception flag is set i.e. exception has
+ * occurred during parsing.
+ */
+ if (parseTreeErrorListener.isExceptionFlag()) {
+ // Get the exception occurred during parsing.
+ ParserException parserException = parseTreeErrorListener.getParserException();
+ parserException.setFileName(yangFile);
+ throw parserException;
+ }
+
+ // Create a walker to walk the parse tree.
+ ParseTreeWalker walker = new ParseTreeWalker();
+
+ // Create a listener implementation class object.
+ TreeWalkListener treeWalker = new TreeWalkListener();
+
+ /**
+ * Walk parse tree, provide call backs to methods in listener and
+ * build data model tree.
+ */
+ walker.walk(treeWalker, tree);
+
+ // Throws an parser exception which has occurred during listener walk.
+ if (treeWalker.getErrorInformation().isErrorFlag()) {
+ // Create object of listener exception
+ ParserException listenerException = new ParserException();
+ listenerException.setMsg(treeWalker.getErrorInformation().getErrorMsg());
+ listenerException.setFileName(yangFile);
+ throw listenerException;
+ }
+
+ // Returns the Root Node of the constructed data model tree.
+ return treeWalker.getRootNode();
+ }
+}
diff --git a/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerValidation.java b/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerValidation.java
new file mode 100644
index 0000000..6ecded3
--- /dev/null
+++ b/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerValidation.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.onosproject.yangutils.parser.impl.parserutils;
+
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/**
+ * Its a utility to carry out listener validation.
+ */
+public final class ListenerValidation {
+
+ /**
+ * Creates a new belongto listener.
+ */
+ private ListenerValidation() {
+ }
+
+ /**
+ * Checks if error is set or parsed data stack is empty.
+ *
+ * @param listener Listener's object.
+ * @param errNode parsable node for which validation needs to be done.
+ * @return validation result.
+ */
+ public static boolean preValidation(TreeWalkListener listener, String errNode) {
+
+ // Check whether error found while walking YANG file, if yes return true.
+ if (listener.getErrorInformation().isErrorFlag()) {
+ return true;
+ }
+
+ // If stack is empty it indicates error condition
+ if (listener.getParsedDataStack().empty()) {
+ listener.getErrorInformation().setErrorFlag(true);
+ listener.getErrorInformation().setErrorMsg("Parsable stack empty at" + errNode + "entry");
+ return true;
+ }
+ return false;
+ }
+}
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diff --git a/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ParseTreeErrorListener.java b/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ParseTreeErrorListener.java
new file mode 100644
index 0000000..d3926df
--- /dev/null
+++ b/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ParseTreeErrorListener.java
@@ -0,0 +1,65 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.onosproject.yangutils.parser.impl.parserutils;
+
+import org.antlr.v4.runtime.BaseErrorListener;
+import org.antlr.v4.runtime.RecognitionException;
+import org.antlr.v4.runtime.Recognizer;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+
+/**
+ * By default, ANTLR sends all errors to standard error, this is changed by
+ * providing this new implementation of interface ANTLRErrorListener. The
+ * interface has a syntaxError() method that applies to both lexer and
+ * parser.
+ */
+public class ParseTreeErrorListener extends BaseErrorListener {
+
+ // Exception of type parser exceptions are catched during parsing.
+ private ParserException parserException = new ParserException();
+
+ // Flag to indicate presence of exception.
+ private boolean exceptionFlag = false;
+
+ /**
+ * Returns the status of exception flag.
+ *
+ * @return flag which contains the status of exception.
+ */
+ public boolean isExceptionFlag() {
+ return exceptionFlag;
+ }
+
+ /**
+ * Returns the parser exception object populated with line, character
+ * position and message.
+ *
+ * @return object of parser exception.
+ */
+ public ParserException getParserException() {
+ return parserException;
+ }
+
+ @Override
+ public void syntaxError(Recognizer<?, ?> recognizer, Object offendingSymbol, int line, int charPositionInLine,
+ String msg, RecognitionException e) {
+ parserException.setLine(line);
+ parserException.setCharPosition(charPositionInLine);
+ parserException.setMsg(msg);
+ exceptionFlag = true;
+ }
+}
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