1  /*
  2    Copyright (C) 2013 Yusuke Suzuki <utatane.tea@gmail.com>
  3  
  4    Redistribution and use in source and binary forms, with or without
  5    modification, are permitted provided that the following conditions are met:
  6  
  7      * Redistributions of source code must retain the above copyright
  8        notice, this list of conditions and the following disclaimer.
  9      * Redistributions in binary form must reproduce the above copyright
 10        notice, this list of conditions and the following disclaimer in the
 11        documentation and/or other materials provided with the distribution.
 12  
 13    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 'AS IS'
 14    AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 15    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 16    ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
 17    DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 18    (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 19    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 20    ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 21    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 22    THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 23  */
 24  
 25  (function () {
 26      'use strict';
 27  
 28      function isExpression(node) {
 29          if (node == null) { return false; }
 30          switch (node.type) {
 31              case 'ArrayExpression':
 32              case 'AssignmentExpression':
 33              case 'BinaryExpression':
 34              case 'CallExpression':
 35              case 'ConditionalExpression':
 36              case 'FunctionExpression':
 37              case 'Identifier':
 38              case 'Literal':
 39              case 'LogicalExpression':
 40              case 'MemberExpression':
 41              case 'NewExpression':
 42              case 'ObjectExpression':
 43              case 'SequenceExpression':
 44              case 'ThisExpression':
 45              case 'UnaryExpression':
 46              case 'UpdateExpression':
 47                  return true;
 48          }
 49          return false;
 50      }
 51  
 52      function isIterationStatement(node) {
 53          if (node == null) { return false; }
 54          switch (node.type) {
 55              case 'DoWhileStatement':
 56              case 'ForInStatement':
 57              case 'ForStatement':
 58              case 'WhileStatement':
 59                  return true;
 60          }
 61          return false;
 62      }
 63  
 64      function isStatement(node) {
 65          if (node == null) { return false; }
 66          switch (node.type) {
 67              case 'BlockStatement':
 68              case 'BreakStatement':
 69              case 'ContinueStatement':
 70              case 'DebuggerStatement':
 71              case 'DoWhileStatement':
 72              case 'EmptyStatement':
 73              case 'ExpressionStatement':
 74              case 'ForInStatement':
 75              case 'ForStatement':
 76              case 'IfStatement':
 77              case 'LabeledStatement':
 78              case 'ReturnStatement':
 79              case 'SwitchStatement':
 80              case 'ThrowStatement':
 81              case 'TryStatement':
 82              case 'VariableDeclaration':
 83              case 'WhileStatement':
 84              case 'WithStatement':
 85                  return true;
 86          }
 87          return false;
 88      }
 89  
 90      function isSourceElement(node) {
 91        return isStatement(node) || node != null && node.type === 'FunctionDeclaration';
 92      }
 93  
 94      function trailingStatement(node) {
 95          switch (node.type) {
 96          case 'IfStatement':
 97              if (node.alternate != null) {
 98                  return node.alternate;
 99              }
100              return node.consequent;
101  
102          case 'LabeledStatement':
103          case 'ForStatement':
104          case 'ForInStatement':
105          case 'WhileStatement':
106          case 'WithStatement':
107              return node.body;
108          }
109          return null;
110      }
111  
112      function isProblematicIfStatement(node) {
113          var current;
114  
115          if (node.type !== 'IfStatement') {
116              return false;
117          }
118          if (node.alternate == null) {
119              return false;
120          }
121          current = node.consequent;
122          do {
123              if (current.type === 'IfStatement') {
124                  if (current.alternate == null)  {
125                      return true;
126                  }
127              }
128              current = trailingStatement(current);
129          } while (current);
130  
131          return false;
132      }
133  
134      module.exports = {
135          isExpression: isExpression,
136          isStatement: isStatement,
137          isIterationStatement: isIterationStatement,
138          isSourceElement: isSourceElement,
139          isProblematicIfStatement: isProblematicIfStatement,
140  
141          trailingStatement: trailingStatement
142      };
143  }());
144  /* vim: set sw=4 ts=4 et tw=80 : */