safe_numerics/doc/boostbook/safe_range.xml

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<!DOCTYPE section PUBLIC "-//Boost//DTD BoostBook XML V1.1//EN"
"http://www.boost.org/tools/boostbook/dtd/boostbook.dtd">
<section id="safe_numerics.safe_range">
  <title>safe_signed_range&lt;MIN, MAX, PP, EP&gt; and
  safe_unsigned_range&lt;MIN, MAX, PP, EP&gt;</title>

  <?dbhtml stop-chunking?>

  <section>
    <title>Description</title>

    <para>This type holds a signed or unsigned integer in the closed range
    [MIN, MAX]. A <code>safe_signed_range&lt;MIN, MAX, PP, EP&gt;</code> or
    <code>safe_unsigned_range&lt;MIN, MAX, PP, EP&gt;</code> can be used
    anywhere an arithmetic type is permitted. Any expression which uses either
    of these types is guaranteed to return an arithmetically correct value or
    to trap in some way.</para>
  </section>

  <section>
    <title>Notation</title>

    <informaltable>
      <tgroup cols="2">
        <colspec align="left" colwidth="1*"/>

        <colspec align="left" colwidth="8*"/>

        <thead>
          <row>
            <entry align="left">Symbol</entry>

            <entry align="left">Description</entry>
          </row>
        </thead>

        <tbody>
          <row>
            <entry><code>MIN, MAX</code></entry>

            <entry>Minimum and maximum values that the range can
            represent.</entry>
          </row>
        </tbody>
      </tgroup>
    </informaltable>
  </section>

  <section>
    <title>Associated Types</title>

    <informaltable>
      <tgroup cols="2">
        <colspec align="left" colwidth="1*"/>

        <colspec align="left" colwidth="8*"/>

        <tbody>
          <row>
            <entry><code>PP</code></entry>

            <entry>Promotion Policy. A type which specifies the result type of
            an expression using safe types.</entry>
          </row>

          <row>
            <entry><code>EP</code></entry>

            <entry>Exception Policy. A type containing members which are
            called when a correct result cannot be returned</entry>
          </row>
        </tbody>
      </tgroup>
    </informaltable>
  </section>

  <section>
    <title>Template Parameters</title>

    <informaltable>
      <tgroup cols="3">
        <colspec align="left" colwidth="1*"/>

        <colspec align="left" colwidth="2*"/>

        <colspec align="left" colwidth="6*"/>

        <thead>
          <row>
            <entry align="left">Parameter</entry>

            <entry align="left">Requirements</entry>

            <entry>Description</entry>
          </row>
        </thead>

        <tbody>
          <row>
            <entry><code>MIN</code></entry>

            <entry>must be a non-negative literal</entry>

            <entry>The minimum non-negative integer value that this type may
            hold</entry>
          </row>

          <row>
            <entry><code>MAX</code></entry>

            <entry>must be a non-negative literal</entry>

            <entry>The maximum non-negative integer value that this type may
            hold</entry>
          </row>

          <row>
            <entry/>

            <entry>MIN &lt;= MAX</entry>

            <entry>must be a valid closed range</entry>
          </row>

          <row>
            <entry><code>PP</code></entry>

            <entry><link linkend="safe_numerics.numeric"><link
            linkend="safe_numerics.promotion_policy">PromotionPolicy&lt;PP&gt;</link></link></entry>

            <entry><para>Default value is <link
            linkend="safe_numerics.promotion_policies.native"><code>boost::numeric::native</code></link></para></entry>
          </row>

          <row>
            <entry><code>EP</code></entry>

            <entry><link linkend="safe_numerics.numeric"><link
            linkend="safe_numerics.exception_policy">Exception
            Policy&lt;EP&gt;</link></link></entry>

            <entry><para>Default value is <link
            linkend="safe_numerics.exception_policies.default_exception_policy"><code>boost::numeric::default_exception_policy</code></link></para></entry>
          </row>
        </tbody>
      </tgroup>
    </informaltable>
  </section>

  <section>
    <title>Model of</title>

    <para><link linkend="safe_numerics.numeric">Integer</link></para>

    <para><link
    linkend="safe_numerics.safe_numeric_concept">SafeNumeric</link></para>
  </section>

  <section>
    <title>Valid Expressions</title>

    <para>Implements all expressions and only those expressions defined by the
    <link linkend="safe_numerics.safe_numeric_concept">SafeNumeric</link> type
    requirements. Thus, the result type of such an expression will be another
    safe type. The actual type of the result of such an expression will depend
    upon the specific promotion policy template parameter.</para>
  </section>

  <section>
    <title>Example of use</title>

    <programlisting>#include &lt;boost/numeric/safe_numerics/safe_range.hpp&gt;

void f(){
    using namespace boost::numeric;
    safe_unsigned_range&lt;7, 24&gt; i
    // since the range is included in [0,255], the underlying type of i 
    // will be an unsigned char.
    i = 0;  // throws out_of_range exception
    i = 9;  // ok
    i *= 9; // throws out_of_range exception
    i = -1; // throws out_of_range exception
    std::uint8_t j = 4;
    auto k = i + j;

    // the range of i is [7, 24] and the range of j is [0,255]
    // if either or both types are safe types, the result is a safe type
    // determined by promotion policy.  With the default native promotion policy
    // k will be safe&lt;unsigned int&gt;
    static_assert(std::is_same&lt;decltype(k), safe&lt;unsigned int&gt;);
  }</programlisting>
  </section>

  <section>
    <title>Header</title>

    <para><filename><ulink url="../../include/safe_range.hpp">#include
    &lt;boost/numeric/safe_numerics/safe_range.hpp&gt;</ulink></filename></para>
  </section>
</section>