org.sonar.plugins.php.api.cfg.ControlFlowGraph Maven / Gradle / Ivy

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/*
 * SonarQube PHP Plugin
 * Copyright (C) 2010-2024 SonarSource SA
 * mailto:info AT sonarsource DOT com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package org.sonar.plugins.php.api.cfg;

import java.util.Collections;
import java.util.EnumSet;
import java.util.Set;
import java.util.WeakHashMap;
import javax.annotation.CheckForNull;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.sonar.php.tree.impl.PHPTree;
import org.sonar.php.utils.Throwables;
import org.sonar.plugins.php.api.tree.ScriptTree;
import org.sonar.plugins.php.api.tree.Tree;
import org.sonar.plugins.php.api.tree.declaration.FunctionDeclarationTree;
import org.sonar.plugins.php.api.tree.declaration.MethodDeclarationTree;
import org.sonar.plugins.php.api.tree.expression.FunctionExpressionTree;
import org.sonar.plugins.php.api.tree.statement.BlockTree;
import org.sonar.plugins.php.api.tree.statement.CatchBlockTree;
import org.sonar.plugins.php.api.tree.statement.ForEachStatementTree;
import org.sonar.plugins.php.api.visitors.CheckContext;

/**
 * The Control Flow Graph
 * for a PHP script or for the body of a function.
 *
 * Each node of the graph represents a list of elements which are executed sequentially.
 * Each node has:
 * 

 * one ore more successor blocks,
 * zero or more predecessor blocks.
 * 
 * 
 * 
 * A Control Flow Graph has a single start node and a single end node.
 * The end node has no successor and no element.
 *
 * WARNING: This is an experimental API, it may change without notice.
 */
public class ControlFlowGraph {

  private static final Logger LOG = LoggerFactory.getLogger(ControlFlowGraph.class);

  public static final Set KINDS_WITH_CONTROL_FLOW = EnumSet.of(
    Tree.Kind.FUNCTION_DECLARATION,
    Tree.Kind.FUNCTION_EXPRESSION,
    Tree.Kind.METHOD_DECLARATION,
    Tree.Kind.SCRIPT);

  private final CfgBlock start;
  private final PhpCfgEndBlock end;
  private final Set blocks;

  // we use WeakHashMap for implementation to allow the trees to be garbage collected
  private static Set failedTrees = Collections.newSetFromMap(new WeakHashMap<>());

  ControlFlowGraph(Set blocks, CfgBlock start, PhpCfgEndBlock end) {
    this.start = start;
    this.end = end;
    this.blocks = blocks;
  }

  /**
   * WARNING: This is an experimental API, it may change without notice.
   */
  public static ControlFlowGraph build(BlockTree body) {
    return new ControlFlowGraphBuilder(body.statements()).getGraph();
  }

  /**
   * WARNING: This is an experimental API, it may change without notice.
   */
  static ControlFlowGraph build(ScriptTree scriptTree) {
    return new ControlFlowGraphBuilder(scriptTree.statements()).getGraph();
  }

  /**
   * WARNING: This is an experimental API, it may change without notice.
   */
  static ControlFlowGraph build(ForEachStatementTree statementTree) {
    return new ControlFlowGraphBuilder(statementTree.statements()).getGraph();
  }

  /**
   * WARNING: This is an experimental API, it may change without notice.
   */
  @CheckForNull
  public static ControlFlowGraph build(Tree tree, CheckContext context) {
    if (failedTrees.contains(tree)) {
      return null;
    }
    try {
      switch (tree.getKind()) {
        case FUNCTION_DECLARATION:
          return build(((FunctionDeclarationTree) tree).body());
        case FUNCTION_EXPRESSION:
          return build(((FunctionExpressionTree) tree).body());
        case METHOD_DECLARATION:
          Tree body = ((MethodDeclarationTree) tree).body();
          if (body.is(Tree.Kind.BLOCK)) {
            return build(((BlockTree) body));
          } else {
            return null;
          }
        case SCRIPT:
          return build(((ScriptTree) tree));
        case FOREACH_STATEMENT:
          return build((ForEachStatementTree) tree);
        case CATCH_BLOCK:
          return build(((CatchBlockTree) tree).block());
        default:
          throw new IllegalStateException("Unexpected tree kind " + tree.getKind());
      }
    } catch (Exception e) {
      LOG.warn("Failed to build control flow graph for file [{}] at line {} (activate debug logs for more details)", context.getPhpFile(), ((PHPTree) tree).getLine());
      LOG.debug(Throwables.getStackTraceAsString(e));
      failedTrees.add(tree);
    }

    return null;
  }

  public CfgBlock start() {
    return start;
  }

  public CfgBlock end() {
    return end;
  }

  /**
   * Includes start and end blocks
   */
  public Set blocks() {
    return blocks;
  }
}