tsreaper commented on code in PR #21393: URL: https://github.com/apache/flink/pull/21393#discussion_r1086577308
########## flink-table/flink-table-code-splitter/src/main/java/org/apache/flink/table/codesplit/BlockStatementSplitter.java: ########## @@ -0,0 +1,326 @@ +/* + * 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.flink.table.codesplit; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.table.codesplit.JavaParser.BlockStatementContext; +import org.apache.flink.table.codesplit.JavaParser.StatementContext; + +import org.antlr.v4.runtime.CharStreams; +import org.antlr.v4.runtime.CommonTokenStream; +import org.antlr.v4.runtime.ParserRuleContext; +import org.antlr.v4.runtime.TokenStreamRewriter; +import org.antlr.v4.runtime.atn.PredictionMode; + +import java.util.ArrayList; +import java.util.Collections; +import java.util.HashMap; +import java.util.List; +import java.util.Map; +import java.util.Map.Entry; + +/** + * Extract statements from IFs, ELSEs and WILEs blocks making them smaller. + * + * <p>BlockStatementSplitter does not recognize if statement operates on local of class member + * variable. Because of that, code must be preprocessed by {@link DeclarationRewriter} which + * converts all local variables extracted as to member variables. + * + * <p><i>Before</i> + * + * <pre><code> + * while (counter > 0) { + * int localA = a + 1000; + * System.out.println(localA); + * if (a > 0) { + * b = a * 2; + * c = b * 2; + * System.out.println(b); + * } else { + * b = a * 3; + * System.out.println(b); + * } + * counter--; + * } + * + * </code></pre> + * + * <p><i>After</i> + * + * <pre><code> + * while (counter > 0) { + * myFun_whileBody0_0(int a); + * if (a > 0) { + * myFun_whileBody0_0_ifBody0(int a); + * } else { + * myFun_whileBody0_0_ifBody1(int a); + * } + * counter--; + * } + * </code></pre> + * + * <p>Where bodies of extracted "methods" are: + * + * <pre><code> + * myFun_whileBody0_0(int a) -> + * int localA = a + 1000; + * System.out.println(localA); + * </code></pre> + * + * <pre><code> + * myFun_whileBody0_0_ifBody0(int a) -> + * b = a * 2; + * c = b * 2; + * System.out.println(b); + * </code></pre> + * + * <pre><code> + * myFun_whileBody0_0_ifBody1(int a) -> + * b = a * 3; + * System.out.println(b); + * </code></pre> + */ +@Internal +public class BlockStatementSplitter { + + private final String code; + + private final String parameters; + + private BlockStatementVisitor visitor; + + /** + * Initialize new BlockStatementSplitter. + * + * @param code a code block that should be rewritten. + * @param parameters parameters definition that should be used for extracted methods. + */ + public BlockStatementSplitter(String code, String parameters) { + this.code = code; + this.parameters = parameters; + } + + /** + * This method extracts statements from IFs, ELSE's and WHILE blocks from block code used during + * initialization of this object. Every entry of returned map can be seen as new method nam (map + * key) and method's body. The block names will be prefixed with provided context. + * + * @param context prefix for extracted blocks. + * @return a map of block name to block statements mappings. The key can be interpreted as name + * of extracted block/method and corresponding List represents individual statements (block' + * lines) for this block. + */ + public Map<String, List<String>> extractBlocks(String context) { + + this.visitor = new BlockStatementVisitor(code, context, parameters); + JavaParser javaParser = new JavaParser(visitor.tokenStream); + javaParser.getInterpreter().setPredictionMode(PredictionMode.SLL); + visitor.visitStatement(javaParser.statement()); + return visitor.getAllBlocks(); + } + + /** + * Rewrite code block that was used for this object initialization. + * + * @return a map which key represent rewritten block name and value represents rewritten code + * block, including calls to extracted methods + */ + public Map<String, String> rewriteBlock() { + visitor.rewrite(); + Map<String, String> rewriteBlocks = new HashMap<>(); + rewriteBlocks.put(visitor.context, visitor.rewriter.getText()); + return rewriteBlocks; + } + + private static void mergeBlocks( + Map<String, List<String>> mergeA, Map<String, List<String>> mergeB) { + + for (Entry<String, List<String>> entry : mergeA.entrySet()) { + mergeB.merge( + entry.getKey(), + entry.getValue(), + (aBlocks, bBlocks) -> { + List<String> merge = new ArrayList<>(aBlocks.size() + bBlocks.size()); + merge.addAll(aBlocks); + merge.addAll(bBlocks); + return merge; + }); + } + } + + private static class BlockStatementVisitor extends JavaParserBaseVisitor<Void> { + + private final List<BlockStatementVisitor> children = new ArrayList<>(); + + private final List<ParserRuleContext> extractedSingleBlocks = new ArrayList<>(); + + private final String context; + + private final CommonTokenStream tokenStream; + + private final TokenStreamRewriter rewriter; + + private final String parameters; + + private int counter = 0; + + private BlockStatementVisitor(String code, String context, String parameters) { + this.tokenStream = new CommonTokenStream(new JavaLexer(CharStreams.fromString(code))); + this.rewriter = new TokenStreamRewriter(tokenStream); + this.context = context; + this.parameters = parameters; + } + + private BlockStatementVisitor( + TokenStreamRewriter rewriter, String context, String parameters) { + this.tokenStream = null; + this.rewriter = rewriter; + this.context = context; + this.parameters = parameters; + } + + @Override + public Void visitStatement(StatementContext ctx) { Review Comment: I understand. If it is difficult to refactor this part of code, at least add detailed comments showing that we're only grouping single statements on the same level, not merging different levels together. In `mergeBlocks` you should also assert that two maps do not have the same key. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@flink.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
