diff options
Diffstat (limited to 'doc/html/proto/users_guide.html')
| -rw-r--r-- | doc/html/proto/users_guide.html | 116 |
1 files changed, 58 insertions, 58 deletions
diff --git a/doc/html/proto/users_guide.html b/doc/html/proto/users_guide.html index 635ee53e2b..b710fd2f60 100644 --- a/doc/html/proto/users_guide.html +++ b/doc/html/proto/users_guide.html @@ -833,7 +833,7 @@ <span class="identifier">i</span> <span class="special">+</span> <span class="number">1</span><span class="special">;</span> </pre> <p> - There is also a <code class="computeroutput"><a class="link" href="../boost/proto/lit_idp728253920.html" title="Function lit">proto::lit()</a></code> function for constructing + There is also a <code class="computeroutput"><a class="link" href="../boost/proto/lit_idp709996480.html" title="Function lit">proto::lit()</a></code> function for constructing a <code class="computeroutput"><a class="link" href="../boost/proto/literal.html" title="Struct template literal">proto::literal<></a></code> in-place. The above expression can simply be written as: </p> @@ -1020,7 +1020,7 @@ In the type computation above, <code class="computeroutput"><span class="identifier">proto</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">as_child</span><span class="special"><></span></code> is a metafunction that ensures its argument is a Proto expression type. If it isn't one already, it becomes a Proto terminal. We'll learn more about this metafunction, along - with <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp731140288.html" title="Function as_child">proto::as_child()</a></code>, its runtime counterpart, + with <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp712882848.html" title="Function as_child">proto::as_child()</a></code>, its runtime counterpart, <a class="link" href="users_guide.html#boost_proto.users_guide.front_end.customizing_expressions_in_your_domain.per_domain_as_child" title="Controlling How Child Expressions Are Captured">later</a>. For now, you can forget about it. </p></td></tr> @@ -1034,7 +1034,7 @@ <span class="identifier">proto</span><span class="special">::</span><span class="identifier">lit</span><span class="special">(</span><span class="number">1</span><span class="special">)(</span><span class="number">2</span><span class="special">)(</span><span class="number">3</span><span class="special">,</span><span class="number">4</span><span class="special">)(</span><span class="number">5</span><span class="special">,</span><span class="number">6</span><span class="special">,</span><span class="number">7</span><span class="special">,</span><span class="number">8</span><span class="special">);</span> </pre> <p> - That may look strange at first. It creates an integer terminal with <code class="computeroutput"><a class="link" href="../boost/proto/lit_idp728253920.html" title="Function lit">proto::lit()</a></code>, and then invokes it like + That may look strange at first. It creates an integer terminal with <code class="computeroutput"><a class="link" href="../boost/proto/lit_idp709996480.html" title="Function lit">proto::lit()</a></code>, and then invokes it like a function again and again. What does it mean? Who knows?! You get to decide when you define an evaluation context or a transform. But more on that later. @@ -1107,9 +1107,9 @@ <p> We could write a <code class="computeroutput"><span class="identifier">pow</span><span class="special">()</span></code> function using code like this, but it's verbose and error prone; it's too - easy to introduce subtle bugs by forgetting to call <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp731140288.html" title="Function as_child">proto::as_child()</a></code> + easy to introduce subtle bugs by forgetting to call <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp712882848.html" title="Function as_child">proto::as_child()</a></code> where necessary, resulting in code that seems to work but sometimes doesn't. - Proto provides a better way to construct expression nodes: <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp728389200.html" title="Function make_expr">proto::make_expr()</a></code>. + Proto provides a better way to construct expression nodes: <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp710131760.html" title="Function make_expr">proto::make_expr()</a></code>. </p> <h6> <a name="boost_proto.users_guide.front_end.making_lazy_functions.h1"></a> @@ -1117,7 +1117,7 @@ Functions Made Simple With <code class="literal">make_expr()</code></a> </h6> <p> - Proto provides a helper for building expression templates called <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp728389200.html" title="Function make_expr">proto::make_expr()</a></code>. We can concisely define + Proto provides a helper for building expression templates called <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp710131760.html" title="Function make_expr">proto::make_expr()</a></code>. We can concisely define the <code class="computeroutput"><span class="identifier">pow</span><span class="special">()</span></code> function with it as below. </p> @@ -1145,22 +1145,22 @@ <p> Subsequent template parameters to <code class="computeroutput"><span class="identifier">proto</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">make_expr</span><span class="special"><></span></code> represent child nodes. If a child type is not already a Proto expression, it is automatically made into a - terminal with <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp731140288.html" title="Function as_child">proto::as_child()</a></code>. + terminal with <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp712882848.html" title="Function as_child">proto::as_child()</a></code>. A type such as <code class="computeroutput"><span class="identifier">pow_fun</span><span class="special"><</span><span class="identifier">Exp</span><span class="special">></span></code> results in terminal that is held by value, whereas a type like <code class="computeroutput"><span class="identifier">Arg</span> <span class="keyword">const</span> <span class="special">&</span></code> (note the reference) indicates that the result should be held by reference. </p> <p> - In the function body is the runtime invocation of <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp728389200.html" title="Function make_expr">proto::make_expr()</a></code>. - It closely mirrors the return type calculation. <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp728389200.html" title="Function make_expr">proto::make_expr()</a></code> + In the function body is the runtime invocation of <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp710131760.html" title="Function make_expr">proto::make_expr()</a></code>. + It closely mirrors the return type calculation. <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp710131760.html" title="Function make_expr">proto::make_expr()</a></code> requires you to specify the node's tag type as a template parameter. The arguments to the function become the node's children. When a child should be stored by value, nothing special needs to be done. When a child should be stored by reference, you must use the <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">ref</span><span class="special">()</span></code> function to wrap the argument. </p> <p> - And that's it! <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp728389200.html" title="Function make_expr">proto::make_expr()</a></code> + And that's it! <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp710131760.html" title="Function make_expr">proto::make_expr()</a></code> is the lazy person's way to make a lazy funtion. </p> </div> @@ -1825,7 +1825,7 @@ <code class="literal">as_child</code> vs. <code class="literal">as_expr</code></a> </h6> <p> - Proto lets you independently customize the behavior of <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp731140288.html" title="Function as_child">proto::as_child()</a></code> and <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp731118320.html" title="Function as_expr">proto::as_expr()</a></code>. + Proto lets you independently customize the behavior of <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp712882848.html" title="Function as_child">proto::as_child()</a></code> and <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp712860880.html" title="Function as_expr">proto::as_expr()</a></code>. Both accept an object <code class="literal">x</code> and return a Proto expression by turning <code class="literal">x</code> it into a Proto terminal if necessary. Although similar, the two functions are used in different situations @@ -1834,7 +1834,7 @@ you want. </p> <p> - To wit: <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp731118320.html" title="Function as_expr">proto::as_expr()</a></code> is typically used by + To wit: <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp712860880.html" title="Function as_expr">proto::as_expr()</a></code> is typically used by <span class="emphasis"><em>you</em></span> to turn an object into a Proto expression that is to be held in a local variable, as so: </p> @@ -1846,11 +1846,11 @@ is guaranteed to be a valid Proto expression. If <code class="computeroutput"><span class="identifier">x</span></code> is a non-Proto object, it is turned into a terminal expression that holds <code class="computeroutput"><span class="identifier">x</span></code> <span class="emphasis"><em>by value</em></span>.<a href="#ftn.boost_proto.users_guide.front_end.customizing_expressions_in_your_domain.per_domain_as_child.f0" class="footnote" name="boost_proto.users_guide.front_end.customizing_expressions_in_your_domain.per_domain_as_child.f0"><sup class="footnote">[28]</sup></a> If <code class="computeroutput"><span class="identifier">x</span></code> is a - Proto object already, <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp731118320.html" title="Function as_expr">proto::as_expr()</a></code> + Proto object already, <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp712860880.html" title="Function as_expr">proto::as_expr()</a></code> returns it <span class="emphasis"><em>by value</em></span> unmodified. </p> <p> - In contrast, <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp731140288.html" title="Function as_child">proto::as_child()</a></code> + In contrast, <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp712882848.html" title="Function as_child">proto::as_child()</a></code> is used internally by Proto to pre-process objects before making them children of another expression. Since it's internal to Proto, you don't see it explicitly, but it's there behind the scenes in expressions like @@ -1860,12 +1860,12 @@ </pre> <p> In this case, Proto builds a plus node from the two children. Both are - pre-processed by passing them to <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp731140288.html" title="Function as_child">proto::as_child()</a></code> + pre-processed by passing them to <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp712882848.html" title="Function as_child">proto::as_child()</a></code> before making them children of the new node. If <code class="computeroutput"><span class="identifier">x</span></code> is not a Proto expression, it becomes one by being wrapped in a Proto - terminal that holds it <span class="emphasis"><em>by reference</em></span>. If <code class="computeroutput"><span class="identifier">x</span></code> is already a Proto expression, <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp731140288.html" title="Function as_child">proto::as_child()</a></code> returns it <span class="emphasis"><em>by + terminal that holds it <span class="emphasis"><em>by reference</em></span>. If <code class="computeroutput"><span class="identifier">x</span></code> is already a Proto expression, <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp712882848.html" title="Function as_child">proto::as_child()</a></code> returns it <span class="emphasis"><em>by reference</em></span> unmodified. Contrast this with the above description - for <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp731118320.html" title="Function as_expr">proto::as_expr()</a></code>. + for <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp712860880.html" title="Function as_expr">proto::as_expr()</a></code>. </p> <p> The table below summarizes the above description. @@ -1945,32 +1945,32 @@ <tr><td align="left" valign="top"><p> There is one important place where Proto uses both <code class="computeroutput"><span class="identifier">as_expr</span></code> <span class="emphasis"><em>and</em></span> <code class="computeroutput"><span class="identifier">as_child</span></code>: - <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp728389200.html" title="Function make_expr">proto::make_expr()</a></code>. The <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp728389200.html" title="Function make_expr">proto::make_expr()</a></code> function requires + <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp710131760.html" title="Function make_expr">proto::make_expr()</a></code>. The <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp710131760.html" title="Function make_expr">proto::make_expr()</a></code> function requires you to specify for each child whether it should be held by value or - by reference. Proto uses <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp731118320.html" title="Function as_expr">proto::as_expr()</a></code> - to pre-process the children to be held by value, and <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp731140288.html" title="Function as_child">proto::as_child()</a></code> for the ones to be + by reference. Proto uses <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp712860880.html" title="Function as_expr">proto::as_expr()</a></code> + to pre-process the children to be held by value, and <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp712882848.html" title="Function as_child">proto::as_child()</a></code> for the ones to be held by reference. </p></td></tr> </table></div> <p> - Now that you know what <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp731140288.html" title="Function as_child">proto::as_child()</a></code> - and <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp731118320.html" title="Function as_expr">proto::as_expr()</a></code> are, where they are + Now that you know what <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp712882848.html" title="Function as_child">proto::as_child()</a></code> + and <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp712860880.html" title="Function as_expr">proto::as_expr()</a></code> are, where they are used, and what they do by default, you may decide that one or both of these functions should have different behavior for your domain. For instance, - given the above description of <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp731140288.html" title="Function as_child">proto::as_child()</a></code>, + given the above description of <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp712882848.html" title="Function as_child">proto::as_child()</a></code>, the following code is always wrong: </p> <pre class="programlisting"><span class="identifier">proto</span><span class="special">::</span><span class="identifier">literal</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> <span class="identifier">i</span><span class="special">(</span><span class="number">0</span><span class="special">);</span> <span class="keyword">auto</span> <span class="identifier">l</span> <span class="special">=</span> <span class="identifier">i</span> <span class="special">+</span> <span class="number">42</span><span class="special">;</span> <span class="comment">// This is WRONG! Don't do this.</span> </pre> <p> - Why is this wrong? Because <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp731140288.html" title="Function as_child">proto::as_child()</a></code> + Why is this wrong? Because <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp712882848.html" title="Function as_child">proto::as_child()</a></code> will turn the integer literal 42 into a Proto terminal that holds a reference to a temporary integer initialized with 42. The lifetime of that temporary ends at the semicolon, guaranteeing that the local <code class="computeroutput"><span class="identifier">l</span></code> is left holding a dangling reference to a deceased integer. What to do? - One answer is to use <code class="computeroutput"><a class="link" href="../boost/proto/deep_copy_idp727047232.html" title="Function template deep_copy">proto::deep_copy()</a></code>. - Another is to customize the behavior of <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp731140288.html" title="Function as_child">proto::as_child()</a></code> + One answer is to use <code class="computeroutput"><a class="link" href="../boost/proto/deep_copy_idp708789792.html" title="Function template deep_copy">proto::deep_copy()</a></code>. + Another is to customize the behavior of <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp712882848.html" title="Function as_child">proto::as_child()</a></code> for your domain. Read on for the details. </p> <h6> @@ -2019,7 +2019,7 @@ </h6> <p> Although less common, Proto also lets you customize the behavior of - <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp731118320.html" title="Function as_expr">proto::as_expr()</a></code> on a per-domain basis. + <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp712860880.html" title="Function as_expr">proto::as_expr()</a></code> on a per-domain basis. The technique is identical to that for <code class="literal">as_child</code>. See below: </p> @@ -2049,7 +2049,7 @@ <p> Let's look again at the problem described above involving the C++11 <code class="computeroutput"><span class="keyword">auto</span></code> keyword and the default - behavior of <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp731140288.html" title="Function as_child">proto::as_child()</a></code>. + behavior of <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp712882848.html" title="Function as_child">proto::as_child()</a></code>. </p> <pre class="programlisting"><span class="identifier">proto</span><span class="special">::</span><span class="identifier">literal</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> <span class="identifier">i</span><span class="special">(</span><span class="number">0</span><span class="special">);</span> <span class="keyword">auto</span> <span class="identifier">l</span> <span class="special">=</span> <span class="identifier">i</span> <span class="special">+</span> <span class="number">42</span><span class="special">;</span> <span class="comment">// This is WRONG! Don't do this.</span> @@ -2059,7 +2059,7 @@ to hold the value 42. The local <code class="computeroutput"><span class="identifier">l</span></code> will be left holding a dangling reference to it after its lifetime is over. What if we want Proto to make expressions safe to store this way - in local variables? We can do so very easily by making <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp731140288.html" title="Function as_child">proto::as_child()</a></code> behave just like <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp731118320.html" title="Function as_expr">proto::as_expr()</a></code>. The following code + in local variables? We can do so very easily by making <code class="computeroutput"><a class="link" href="../boost/proto/as_child_idp712882848.html" title="Function as_child">proto::as_child()</a></code> behave just like <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp712860880.html" title="Function as_expr">proto::as_expr()</a></code>. The following code achieves this: </p> <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">E</span> <span class="special">></span> @@ -2782,7 +2782,7 @@ </h6> <p> There is no simpler expression than a terminal, and no more basic operation - than extracting its value. As we've already seen, that is what <code class="computeroutput"><a class="link" href="../boost/proto/value_idp731209856.html" title="Function value">proto::value()</a></code> is for. + than extracting its value. As we've already seen, that is what <code class="computeroutput"><a class="link" href="../boost/proto/value_idp712952416.html" title="Function value">proto::value()</a></code> is for. </p> <pre class="programlisting"><span class="identifier">proto</span><span class="special">::</span><span class="identifier">terminal</span><span class="special"><</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">ostream</span> <span class="special">&</span> <span class="special">>::</span><span class="identifier">type</span> <span class="identifier">cout_</span> <span class="special">=</span> <span class="special">{</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special">};</span> @@ -2793,7 +2793,7 @@ <span class="identifier">assert</span><span class="special">(</span> <span class="special">&</span><span class="identifier">sout</span> <span class="special">==</span> <span class="special">&</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">);</span> </pre> <p> - To compute the return type of the <code class="computeroutput"><a class="link" href="../boost/proto/value_idp731209856.html" title="Function value">proto::value()</a></code> + To compute the return type of the <code class="computeroutput"><a class="link" href="../boost/proto/value_idp712952416.html" title="Function value">proto::value()</a></code> function, you can use <code class="computeroutput"><a class="link" href="../boost/proto/result_of/value.html" title="Struct template value">proto::result_of::value<></a></code>. When the parameter to <code class="computeroutput"><a class="link" href="../boost/proto/result_of/value.html" title="Struct template value">proto::result_of::value<></a></code> is a non-reference type, the result type of the metafunction is the type @@ -2925,7 +2925,7 @@ <p> Each non-terminal node in an expression tree corresponds to an operator in an expression, and the children correspond to the operands, or arguments - of the operator. To access them, you can use the <code class="computeroutput"><a class="link" href="../boost/proto/child_c_idp731190800.html" title="Function child_c">proto::child_c()</a></code> + of the operator. To access them, you can use the <code class="computeroutput"><a class="link" href="../boost/proto/child_c_idp712933360.html" title="Function child_c">proto::child_c()</a></code> function template, as demonstrated below: </p> <pre class="programlisting"><span class="identifier">proto</span><span class="special">::</span><span class="identifier">terminal</span><span class="special"><</span><span class="keyword">int</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">i</span> <span class="special">=</span> <span class="special">{</span><span class="number">42</span><span class="special">};</span> @@ -3091,11 +3091,11 @@ <p> Most operators in C++ are unary or binary, so accessing the only operand, or the left and right operands, are very common operations. For this reason, - Proto provides the <code class="computeroutput"><a class="link" href="../boost/proto/child_idp731162304.html" title="Function child">proto::child()</a></code>, - <code class="computeroutput"><a class="link" href="../boost/proto/left_idp731222320.html" title="Function left">proto::left()</a></code>, and <code class="computeroutput"><a class="link" href="../boost/proto/right_idp731236800.html" title="Function right">proto::right()</a></code> - functions. <code class="computeroutput"><a class="link" href="../boost/proto/child_idp731162304.html" title="Function child">proto::child()</a></code> and <code class="computeroutput"><a class="link" href="../boost/proto/left_idp731222320.html" title="Function left">proto::left()</a></code> + Proto provides the <code class="computeroutput"><a class="link" href="../boost/proto/child_idp712904864.html" title="Function child">proto::child()</a></code>, + <code class="computeroutput"><a class="link" href="../boost/proto/left_idp712964880.html" title="Function left">proto::left()</a></code>, and <code class="computeroutput"><a class="link" href="../boost/proto/right_idp712979360.html" title="Function right">proto::right()</a></code> + functions. <code class="computeroutput"><a class="link" href="../boost/proto/child_idp712904864.html" title="Function child">proto::child()</a></code> and <code class="computeroutput"><a class="link" href="../boost/proto/left_idp712964880.html" title="Function left">proto::left()</a></code> are synonymous with <code class="computeroutput"><span class="identifier">proto</span><span class="special">::</span><span class="identifier">child_c</span><span class="special"><</span><span class="number">0</span><span class="special">>()</span></code>, - and <code class="computeroutput"><a class="link" href="../boost/proto/right_idp731236800.html" title="Function right">proto::right()</a></code> is synonymous with <code class="computeroutput"><span class="identifier">proto</span><span class="special">::</span><span class="identifier">child_c</span><span class="special"><</span><span class="number">1</span><span class="special">>()</span></code>. + and <code class="computeroutput"><a class="link" href="../boost/proto/right_idp712979360.html" title="Function right">proto::right()</a></code> is synonymous with <code class="computeroutput"><span class="identifier">proto</span><span class="special">::</span><span class="identifier">child_c</span><span class="special"><</span><span class="number">1</span><span class="special">>()</span></code>. </p> <p> There are also <code class="computeroutput"><a class="link" href="../boost/proto/result_of/child.html" title="Struct template child">proto::result_of::child<></a></code>, @@ -3130,7 +3130,7 @@ all intermediate nodes and the terminals are held <span class="emphasis"><em>by value</em></span>. That way, you can safely assign the expression template to a local variable or return it from a function without worrying about dangling references. - You can do this with <code class="computeroutput"><a class="link" href="../boost/proto/deep_copy_idp727047232.html" title="Function template deep_copy">proto::deep_copy()</a></code> + You can do this with <code class="computeroutput"><a class="link" href="../boost/proto/deep_copy_idp708789792.html" title="Function template deep_copy">proto::deep_copy()</a></code> as fo llows: </p> <pre class="programlisting"><span class="comment">// OK, "ex" has no dangling references</span> @@ -3165,7 +3165,7 @@ <th align="left">Note</th> </tr> <tr><td align="left" valign="top"><p> - <code class="computeroutput"><a class="link" href="../boost/proto/deep_copy_idp727047232.html" title="Function template deep_copy">proto::deep_copy()</a></code> makes no exception for + <code class="computeroutput"><a class="link" href="../boost/proto/deep_copy_idp708789792.html" title="Function template deep_copy">proto::deep_copy()</a></code> makes no exception for arrays, which it stores by value. That can potentially cause a large amount of data to be copied. </p></td></tr> @@ -3178,7 +3178,7 @@ </h4></div></div></div> <p> Proto provides a utility for pretty-printing expression trees that comes - in very handy when you're trying to debug your EDSL. It's called <code class="computeroutput"><a class="link" href="../boost/proto/display_expr_idp726944752.html" title="Function display_expr">proto::display_expr()</a></code>, and you pass it the expression + in very handy when you're trying to debug your EDSL. It's called <code class="computeroutput"><a class="link" href="../boost/proto/display_expr_idp708687312.html" title="Function display_expr">proto::display_expr()</a></code>, and you pass it the expression to print and optionally, an <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ostream</span></code> to which to send the output. Consider: </p> @@ -3195,7 +3195,7 @@ , terminal(42) )</pre> <p> - In order to call <code class="computeroutput"><a class="link" href="../boost/proto/display_expr_idp726944752.html" title="Function display_expr">proto::display_expr()</a></code>, + In order to call <code class="computeroutput"><a class="link" href="../boost/proto/display_expr_idp708687312.html" title="Function display_expr">proto::display_expr()</a></code>, all the terminals in the expression must be Streamable (that is, they can be written to a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ostream</span></code>). In addition, the tag types must all be Streamable as well. Here is an example that includes a custom @@ -4109,8 +4109,8 @@ <span class="special">+</span> <span class="number">2</span> <span class="special">+</span> <span class="number">3</span> <span class="special">+</span> <span class="number">4</span></code> does not describe a flat sequence of terminals --- it describes a binary tree. We can treat it as a flat - sequence of terminals, however, using Proto's <code class="computeroutput"><a class="link" href="../boost/proto/flatten_idp728095472.html" title="Function flatten">proto::flatten()</a></code> - function. <code class="computeroutput"><a class="link" href="../boost/proto/flatten_idp728095472.html" title="Function flatten">proto::flatten()</a></code> returns a view which makes + sequence of terminals, however, using Proto's <code class="computeroutput"><a class="link" href="../boost/proto/flatten_idp709838032.html" title="Function flatten">proto::flatten()</a></code> + function. <code class="computeroutput"><a class="link" href="../boost/proto/flatten_idp709838032.html" title="Function flatten">proto::flatten()</a></code> returns a view which makes a tree appear as a flat Fusion sequence. If the top-most node has a tag type <code class="computeroutput"><span class="identifier">T</span></code>, then the elements of the flattened sequence are the child nodes that do <span class="emphasis"><em>not</em></span> @@ -5145,8 +5145,8 @@ expression ::= term (('+' term) | ('-' term))* <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> A <span class="emphasis"><em>context</em></span> is like a function object that you pass - along with an expression to the <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp727214672.html" title="Function eval">proto::eval()</a></code> - function. It associates behaviors with node types. <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp727214672.html" title="Function eval">proto::eval()</a></code> + along with an expression to the <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp708957232.html" title="Function eval">proto::eval()</a></code> + function. It associates behaviors with node types. <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp708957232.html" title="Function eval">proto::eval()</a></code> walks the expression and invokes your context at each node. </li> <li class="listitem"> @@ -5186,13 +5186,13 @@ expression ::= term (('+' term) | ('-' term))* </dl></div> <p> Once you have constructed a Proto expression tree, either by using Proto's - operator overloads or with <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp728389200.html" title="Function make_expr">proto::make_expr()</a></code> + operator overloads or with <code class="computeroutput"><a class="link" href="../boost/proto/make_expr_idp710131760.html" title="Function make_expr">proto::make_expr()</a></code> and friends, you probably want to actually <span class="emphasis"><em>do</em></span> something with it. The simplest option is to use <code class="computeroutput"><span class="identifier">proto</span><span class="special">::</span><span class="identifier">eval</span><span class="special">()</span></code>, a generic expression evaluator. To use - <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp727214672.html" title="Function eval">proto::eval()</a></code>, you'll need to define - a <span class="emphasis"><em>context</em></span> that tells <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp727214672.html" title="Function eval">proto::eval()</a></code> + <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp708957232.html" title="Function eval">proto::eval()</a></code>, you'll need to define + a <span class="emphasis"><em>context</em></span> that tells <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp708957232.html" title="Function eval">proto::eval()</a></code> how each node should be evaluated. This section goes through the nuts and - bolts of using <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp727214672.html" title="Function eval">proto::eval()</a></code>, defining evaluation contexts, + bolts of using <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp708957232.html" title="Function eval">proto::eval()</a></code>, defining evaluation contexts, and using the contexts that Proto provides. </p> <div class="note"><table border="0" summary="Note"> @@ -5263,11 +5263,11 @@ expression ::= term (('+' term) | ('-' term))* <span class="special">}</span> </pre> <p> - Given an expression and an evaluation context, using <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp727214672.html" title="Function eval">proto::eval()</a></code> - is quite simple. Simply pass the expression and the context to <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp727214672.html" title="Function eval">proto::eval()</a></code> and it does the rest + Given an expression and an evaluation context, using <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp708957232.html" title="Function eval">proto::eval()</a></code> + is quite simple. Simply pass the expression and the context to <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp708957232.html" title="Function eval">proto::eval()</a></code> and it does the rest and returns the result. You can use the <code class="computeroutput"><span class="identifier">eval</span><span class="special"><></span></code> metafunction in the <code class="computeroutput"><span class="identifier">proto</span><span class="special">::</span><span class="identifier">result_of</span></code> namespace to compute the - return type of <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp727214672.html" title="Function eval">proto::eval()</a></code>. The following demonstrates - a use of <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp727214672.html" title="Function eval">proto::eval()</a></code>: + return type of <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp708957232.html" title="Function eval">proto::eval()</a></code>. The following demonstrates + a use of <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp708957232.html" title="Function eval">proto::eval()</a></code>: </p> <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Expr</span><span class="special">></span> <span class="keyword">typename</span> <span class="identifier">proto</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">eval</span><span class="special"><</span><span class="identifier">Expr</span> <span class="keyword">const</span><span class="special">,</span> <span class="identifier">MyContext</span><span class="special">>::</span><span class="identifier">type</span> @@ -5281,9 +5281,9 @@ expression ::= term (('+' term) | ('-' term))* <span class="special">}</span> </pre> <p> - What <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp727214672.html" title="Function eval">proto::eval()</a></code> does is also very simple. + What <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp708957232.html" title="Function eval">proto::eval()</a></code> does is also very simple. It defers most of the work to the context itself. Here essentially is - the implementation of <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp727214672.html" title="Function eval">proto::eval()</a></code>: + the implementation of <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp708957232.html" title="Function eval">proto::eval()</a></code>: </p> <pre class="programlisting"><span class="comment">// eval() dispatches to a nested "eval<>" function</span> <span class="comment">// object within the Context:</span> @@ -5296,7 +5296,7 @@ expression ::= term (('+' term) | ('-' term))* <span class="special">}</span> </pre> <p> - Really, <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp727214672.html" title="Function eval">proto::eval()</a></code> is nothing more than + Really, <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp708957232.html" title="Function eval">proto::eval()</a></code> is nothing more than a thin wrapper that dispatches to the appropriate handler within the context class. In the next section, we'll see how to implement a context class from scratch. @@ -5308,7 +5308,7 @@ expression ::= term (('+' term) | ('-' term))* an Evaluation Context</a> </h5></div></div></div> <p> - As we saw in the previous section, there is really not much to the <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp727214672.html" title="Function eval">proto::eval()</a></code> function. Rather, all + As we saw in the previous section, there is really not much to the <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp708957232.html" title="Function eval">proto::eval()</a></code> function. Rather, all the interesting expression evaluation goes on within a context class. This section shows how to implement one from scratch. </p> @@ -5414,7 +5414,7 @@ expression ::= term (('+' term) | ('-' term))* <span class="special">};</span> </pre> <p> - Now we can use <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp727214672.html" title="Function eval">proto::eval()</a></code> with the context class + Now we can use <code class="computeroutput"><a class="link" href="../boost/proto/eval_idp708957232.html" title="Function eval">proto::eval()</a></code> with the context class above to evaluate calculator expressions as follows: </p> <pre class="programlisting"><span class="comment">// Evaluate an expression with a calculator_context</span> @@ -11034,7 +11034,7 @@ minus( <div class="footnotes"> <br><hr style="width:100; text-align:left;margin-left: 0"> <div id="ftn.boost_proto.users_guide.front_end.customizing_expressions_in_your_domain.per_domain_as_child.f0" class="footnote"><p><a href="#boost_proto.users_guide.front_end.customizing_expressions_in_your_domain.per_domain_as_child.f0" class="para"><sup class="para">[28] </sup></a> - It's not always possible to hold something by value. By default, <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp731118320.html" title="Function as_expr">proto::as_expr()</a></code> makes an exception + It's not always possible to hold something by value. By default, <code class="computeroutput"><a class="link" href="../boost/proto/as_expr_idp712860880.html" title="Function as_expr">proto::as_expr()</a></code> makes an exception for functions, abstract types, and iostreams (types derived from <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ios_base</span></code>). These objects are held by reference. All others are held by value, even arrays. </p></div> |