ceph/src/boost/libs/proto/doc/reference/concepts/Domain.xml

   1 <?xml version="1.0" ?>
   2 <!--
   3   Copyright 2010 Eric Niebler
   4
   5   Distributed under the Boost
   6   Software License, Version 1.0. (See accompanying
   7   file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   8   -->
   9 <concept name="Domain" category="utility">
  10   <param name="Domain" role="domain-type" />
  11   <param name="Expr" role="expression-type" />
  12   <param name="Object" role="object-type" />
  13
  14   <models-sentence>
  15     The type <arg num="1" /> must be a model of <self/>. It also
  16     models Unary Polymorphic Function.
  17   </models-sentence>
  18
  19   <models-sentence>
  20     The type <arg num="2" /> must be a model of <conceptname>Expr</conceptname>
  21   </models-sentence>
  22
  23   <description>
  24     <para>
  25       A Domain creates an association between expressions and a so-called
  26       generator, which is a function that maps an expression in the default
  27       domain to an equivalent expression in this Domain. It also associates
  28       an expression with a grammar, to which all expressions within this
  29       Domain must conform.
  30     </para>
  31   </description>
  32
  33   <notation variables="d">
  34     <sample-value>
  35       <type name="Domain" />
  36     </sample-value>
  37   </notation>
  38
  39   <notation variables="e">
  40     <sample-value>
  41       <type name="Expr" />
  42     </sample-value>
  43   </notation>
  44
  45   <notation variables="o">
  46     <sample-value>
  47       <type name="Object" />
  48     </sample-value>
  49   </notation>
  50
  51   <associated-type name="proto_grammar">
  52     <get-member-type name="proto_grammar">
  53       <type name="Domain"/>
  54     </get-member-type>
  55     <description>
  56       <simpara>The grammar to which every expression in this Domain
  57         must conform.</simpara>
  58     </description>
  59   </associated-type>
  60
  61   <associated-type name="proto_generator">
  62     <get-member-type name="proto_generator">
  63       <type name="Domain"/>
  64     </get-member-type>
  65     <description>
  66       <simpara>
  67         A Unary Polymorphic Function that accepts expressions in the
  68         default domain and emits expressions in this Domain.
  69       </simpara>
  70     </description>
  71   </associated-type>
  72
  73   <associated-type name="proto_super_domain">
  74     <get-member-type name="proto_super_domain">
  75       <type name="Domain"/>
  76     </get-member-type>
  77     <description>
  78       <simpara>
  79         The Domain that is a super-domain of this domain, if
  80         any such domain exists. If not, it is some unspecified
  81         type.
  82       </simpara>
  83     </description>
  84   </associated-type>
  85
  86   <associated-type name="result_type">
  87     <get-member-type name="type">
  88       <apply-template name="boost::result_of">
  89         <type name="Domain(Expr)"/>
  90       </apply-template>
  91     </get-member-type>
  92     <description>
  93       <simpara>
  94         The type of the result of applying
  95         <computeroutput>proto_generator</computeroutput> to
  96         the specified expression type. The result is required to
  97         model <conceptname>Expr</conceptname>. The domain type
  98         associated with <computeroutput>result_type</computeroutput>
  99         (<computeroutput>result_type::proto_domain</computeroutput>)
 100         is required to be the same type as this Domain.
 101       </simpara>
 102     </description>
 103   </associated-type>
 104
 105   <associated-type name="as_expr_result_type">
 106     <get-member-type name="result_type">
 107       <apply-template name="Domain::as_expr">
 108         <type name="Object"/>
 109       </apply-template>
 110     </get-member-type>
 111     <description>
 112       <simpara>
 113         The result of converting some type to a Proto expression
 114         type in this domain. This is used, for instance, when
 115         calculating the type of a variable to hold a Proto
 116         expression.
 117         <computeroutput>as_expr_result_type</computeroutput>
 118         models
 119         <computeroutput><conceptname>Expr</conceptname></computeroutput>.
 120       </simpara>
 121     </description>
 122   </associated-type>
 123
 124   <associated-type name="as_child_result_type">
 125     <get-member-type name="result_type">
 126       <apply-template name="Domain::as_child">
 127         <type name="Object"/>
 128       </apply-template>
 129     </get-member-type>
 130     <description>
 131       <simpara>
 132         The result of converting some type to a Proto expression
 133         type in this domain. This is used, for instance, to
 134         compute the type of an object suitable for storage
 135         as a child in an expression tree.
 136         <computeroutput>as_child_result_type</computeroutput>
 137         models
 138         <computeroutput><conceptname>Expr</conceptname></computeroutput>.
 139       </simpara>
 140     </description>
 141   </associated-type>
 142
 143   <valid-expression name="Apply Generator">
 144     <apply-function name="d">
 145       <sample-value>
 146         <type name="Expr"/>
 147       </sample-value>
 148     </apply-function>
 149     <return-type>
 150       <require-same-type testable="yes">
 151         <type name="result_type"/>
 152       </require-same-type>
 153     </return-type>
 154     <semantics>
 155       The result of applying <computeroutput>proto_generator</computeroutput>
 156       to the specified expression.
 157     </semantics>
 158   </valid-expression>
 159
 160   <valid-expression name="As Expression">
 161     <apply-function name="Domain::as_expr&lt; Object &gt;()">
 162       <sample-value>
 163         <type name="Object"/>
 164       </sample-value>
 165     </apply-function>
 166     <return-type>
 167       <require-same-type testable="yes">
 168         <type name="as_expr_result_type"/>
 169       </require-same-type>
 170     </return-type>
 171     <semantics>
 172       The result of converting some object to a Proto expression
 173       in this domain. It returns a Proto expression object that
 174       is suitable for storage in a variable. It should return a
 175       new object, which may be a copy of the object passed in.
 176     </semantics>
 177   </valid-expression>
 178
 179   <valid-expression name="As Child">
 180     <apply-function name="Domain::as_child&lt; Object &gt;()">
 181       <sample-value>
 182         <type name="Object"/>
 183       </sample-value>
 184     </apply-function>
 185     <return-type>
 186       <require-same-type testable="yes">
 187         <type name="as_child_result_type"/>
 188       </require-same-type>
 189     </return-type>
 190     <semantics>
 191       The result of converting some object to a Proto expression
 192       in this domain. It returns an object suitable for storage
 193       as a child in an expression tree, which may simply be a
 194       reference to the object passed in.
 195     </semantics>
 196   </valid-expression>
 197
 198   <example-model>
 199     <type name="boost::proto::default_domain" />
 200   </example-model>
 201
 202 </concept>