// Copyright 2014 Google Inc. All rights reserved.
//
// 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 com.google.devtools.build.lib.syntax;

import com.google.devtools.build.lib.syntax.DictionaryLiteral.DictionaryEntryLiteral;
import com.google.devtools.build.lib.syntax.IfStatement.ConditionalStatements;

import java.util.List;
import java.util.Map;

/**
 * A visitor for visiting the nodes in the syntax tree left to right, top to
 * bottom.
 */
public class SyntaxTreeVisitor {

  public void visit(ASTNode node) {
    // dispatch to the node specific method
    node.accept(this);
  }

  public void visitAll(List<? extends ASTNode> nodes) {
    for (ASTNode node : nodes) {
      visit(node);
    }
  }

  // node specific visit methods
  public void visit(Argument.Passed node) {
    visit(node.getValue());
  }

  public void visit(BuildFileAST node) {
    visitAll(node.getStatements());
    visitAll(node.getComments());
  }

  public void visit(BinaryOperatorExpression node) {
    visit(node.getLhs());
    visit(node.getRhs());
  }

  public void visit(FuncallExpression node) {
    visit(node.getFunction());
    visitAll(node.getArguments());
  }

  public void visit(Ident node) {
  }

  public void visit(ListComprehension node) {
    visit(node.getElementExpression());
    for (Map.Entry<LValue, Expression> list : node.getLists()) {
      visit(list.getKey().getExpression());
      visit(list.getValue());
    }
  }

  public void accept(DictComprehension node) {
    visit(node.getKeyExpression());
    visit(node.getValueExpression());
    visit(node.getLoopVar().getExpression());
    visit(node.getListExpression());
  }

  public void visit(ListLiteral node) {
    visitAll(node.getElements());
  }

  public void visit(IntegerLiteral node) {
  }

  public void visit(StringLiteral node) {
  }

  public void visit(AssignmentStatement node) {
    visit(node.getLValue().getExpression());
    visit(node.getExpression());
  }

  public void visit(ExpressionStatement node) {
    visit(node.getExpression());
  }

  public void visit(IfStatement node) {
    for (ConditionalStatements stmt : node.getThenBlocks()) {
      visit(stmt);
    }
    for (Statement stmt : node.getElseBlock()) {
      visit(stmt);
    }
  }

  public void visit(ConditionalStatements node) {
    visit(node.getCondition());
    for (Statement stmt : node.getStmts()) {
      visit(stmt);
    }
  }

  public void visit(FunctionDefStatement node) {
    visit(node.getIdent());
    List<Expression> defaults = node.getArgs().getDefaultValues();
    if (defaults != null) {
      for (Expression expr : defaults) {
        visit(expr);
      }
    }
    for (Statement stmt : node.getStatements()) {
      visit(stmt);
    }
  }

  public void visit(DictionaryLiteral node) {
    for (DictionaryEntryLiteral entry : node.getEntries()) {
      visit(entry);
    }
  }

  public void visit(DictionaryEntryLiteral node) {
    visit(node.getKey());
    visit(node.getValue());
  }

  public void visit(NotExpression node) {
    visit(node.getExpression());
  }

  public void visit(Comment node) {
  }

  public void visit(ConditionalExpression node) {
    visit(node.getThenCase());
    visit(node.getCondition());
    if (node.getElseCase() != null) {
      visit(node.getElseCase());
    }
  }
}