1 | // |
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2 | // Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo |
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3 | // |
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4 | // The contents of this file are covered under the licence agreement in the |
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5 | // file "LICENCE" distributed with Cforall. |
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6 | // |
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7 | // Node.hpp -- |
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8 | // |
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9 | // Author : Thierry Delisle |
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10 | // Created On : Wed May 8 10:27:04 2019 |
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11 | // Last Modified By : Aaron B. Moss |
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12 | // Last Modified On : Wed May 8 11:00:00 2019 |
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13 | // Update Count : 2 |
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14 | // |
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15 | |
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16 | #pragma once |
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17 | |
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18 | #include <cassert> |
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19 | #include <iosfwd> |
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20 | |
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21 | namespace ast { |
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22 | |
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23 | class Visitor; |
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24 | |
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25 | /// Base class for all AST nodes. |
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26 | /// Keeps both strong and weak reference counts. |
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27 | class Node { |
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28 | public: |
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29 | // override defaults to ensure assignment doesn't |
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30 | // change/share reference counts |
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31 | Node() = default; |
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32 | Node(const Node&) : strong_ref(0), weak_ref(0) {} |
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33 | Node(Node&&) : strong_ref(0), weak_ref(0) {} |
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34 | Node& operator= (const Node&) = delete; |
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35 | Node& operator= (Node&&) = delete; |
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36 | virtual ~Node() = default; |
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37 | |
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38 | virtual Node* accept( Visitor& v ) = 0; |
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39 | |
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40 | /// Types of node references |
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41 | enum class ref_type { |
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42 | strong, |
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43 | weak |
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44 | }; |
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45 | |
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46 | inline void increment(ref_type ref) const { |
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47 | switch (ref) { |
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48 | case ref_type::strong: strong_ref++; break; |
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49 | case ref_type::weak : weak_ref ++; break; |
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50 | } |
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51 | } |
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52 | |
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53 | inline void decrement(ref_type ref) const { |
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54 | switch (ref) { |
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55 | case ref_type::strong: strong_ref--; break; |
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56 | case ref_type::weak : weak_ref --; break; |
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57 | } |
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58 | |
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59 | if(!strong_ref && !weak_ref) { |
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60 | delete this; |
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61 | } |
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62 | } |
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63 | |
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64 | template<typename node_t> |
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65 | friend auto mutate(const node_t * node); |
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66 | |
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67 | private: |
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68 | /// Make a copy of this node; should be overridden in subclass with more precise return type |
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69 | virtual Node* clone() const = 0; |
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70 | |
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71 | mutable size_t strong_ref = 0; |
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72 | mutable size_t weak_ref = 0; |
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73 | }; |
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74 | |
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75 | // Mutate a node, non-member function to avoid static type |
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76 | // problems and be able to use auto return |
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77 | template<typename node_t> |
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78 | auto mutate(const node_t * node) { |
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79 | assertf( |
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80 | node->strong_count >= 1, |
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81 | "Error: attempting to mutate a node that appears to have been linked" |
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82 | ); |
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83 | if (node->strong_count == 1) { |
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84 | return const_cast<node_t *>(node); |
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85 | } |
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86 | |
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87 | assertf( |
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88 | node->weak_count == 0, |
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89 | "Error: mutating node with weak references to it will invalided some references" |
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90 | ); |
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91 | return node->clone(); |
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92 | } |
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93 | |
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94 | std::ostream& operator<< ( std::ostream& out, const Node* node ); |
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95 | |
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96 | // Base class for the smart pointer types |
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97 | // should never really be used. |
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98 | template< typename node_t, enum Node::ref_type ref_t> |
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99 | class ptr_base { |
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100 | public: |
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101 | ptr_base() : node(nullptr) {} |
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102 | ptr_base( node_t * n ) : node(n) { if( !node ) node->increment(ref_t); } |
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103 | ~ptr_base() { if( node ) node->decrement(ref_t); } |
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104 | |
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105 | template< enum Node::ref_type o_ref_t > |
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106 | ptr_base( const ptr_base<node_t, o_ref_t> & o ) : node(o.node) { |
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107 | if( !node ) return; |
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108 | node->increment(ref_t); |
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109 | } |
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110 | |
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111 | template< enum Node::ref_type o_ref_t > |
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112 | ptr_base( ptr_base<node_t, o_ref_t> && o ) : node(o.node) { |
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113 | if( node ) node->increment(ref_t); |
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114 | } |
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115 | |
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116 | template< enum Node::ref_type o_ref_t > |
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117 | ptr_base & operator=( const ptr_base<node_t, o_ref_t> & o ) { |
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118 | assign(o.node); |
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119 | return *this; |
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120 | } |
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121 | |
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122 | template< enum Node::ref_type o_ref_t > |
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123 | ptr_base & operator=( ptr_base<node_t, o_ref_t> && o ) { |
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124 | if(o.node == node) return *this; |
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125 | assign(o.node); |
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126 | return *this; |
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127 | } |
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128 | |
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129 | const node_t * get() const { return node; } |
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130 | const node_t * operator->() const { return node; } |
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131 | const node_t & operator* () const { return *node; } |
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132 | explicit operator bool() const { return node; } |
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133 | operator const node_t * const() const { return node; } |
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134 | |
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135 | template<typename o_node_t> |
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136 | const o_node_t * as() const { return dynamic_cast<o_node_t *>(node); } |
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137 | |
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138 | using ptr = const node_t *; |
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139 | |
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140 | private: |
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141 | void assign(node_t * other ) { |
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142 | if( other ) other->increment(ref_t); |
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143 | if( node ) node ->decrement(ref_t); |
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144 | node = other; |
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145 | } |
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146 | |
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147 | protected: |
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148 | node_t * node; |
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149 | }; |
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150 | |
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151 | /// Owning pointer to node |
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152 | template< typename node_t > |
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153 | using ptr = ptr_base< node_t, Node::ref_type::strong >; |
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154 | |
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155 | /// Observing pointer to node |
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156 | template< typename node_t > |
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157 | using readonly = ptr_base< node_t, Node::ref_type::weak >; |
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158 | } |
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159 | |
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160 | // Local Variables: // |
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161 | // tab-width: 4 // |
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162 | // mode: c++ // |
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163 | // compile-command: "make install" // |
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164 | // End: // |
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