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Added BOOST_PP_ENUM, BOOST_PP_ENUM_SHIFTED, BOOST_PP_FOR,

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BOOST_PP_EXPAND


[SVN r12368]
This commit is contained in:
Vesa Karvonen
2002-01-20 16:25:09 +00:00
parent 7653a0a42a
commit 73218bea71
9 changed files with 292 additions and 11 deletions
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14
doc/reference/while_8hpp.html
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@ -54,9 +54,9 @@ Iterates F(D,X) while C(D,X) is true.
<p>
<b>C</b> is the condition for iteration. It must expand to a decimal integer literal.
<p>
<b>F</b> is the iterated function. Note that if the state is a tuple, then F(D,X) usually expands to a tuple of the same number of elements.
<b>F</b> is the iterated macro. Note that if the state is a tuple, then F(D,X) usually expands to a tuple of the same number of elements.
<p>
<b>D</b> is the recursion depth and should only be used as a parameter to other functions implemented using <a class="el" href="while_8hpp.html#a0">BOOST_PP_WHILE</a>(). Such functions include <a class="el" href="add_8hpp.html#a0">BOOST_PP_ADD</a>() and other arithmetic operations. For each function implemented using <a class="el" href="while_8hpp.html#a0">BOOST_PP_WHILE</a>(), there is a version of the function, distinguished by the _D suffix (e.g. BOOST_PP_ADD_D()), that accepts an additional recursion depth as the first parameter. This technique is necessary to avoid recursively expanding the same macro again, which is not permitted by the C/C++ preprocessor.
<b>D</b> is the recursion depth and should only be used as a parameter to other macros implemented using <a class="el" href="while_8hpp.html#a0">BOOST_PP_WHILE</a>(). Such macros include <a class="el" href="add_8hpp.html#a0">BOOST_PP_ADD</a>() and other arithmetic operations. For each macro implemented using <a class="el" href="while_8hpp.html#a0">BOOST_PP_WHILE</a>(), there is a version of the macro, distinguished by the _D suffix (e.g. BOOST_PP_ADD_D()), that accepts an additional recursion depth as the first parameter. This technique is necessary to avoid recursively expanding the same macro again, which is not permitted by the C/C++ preprocessor.
<p>
NOTE: The value of the D parameter may exceed BOOST_PP_LIMIT_MAG.
<p>
@ -69,13 +69,13 @@ Here is a trivial example that simply counts down from N to 0 ultimately expandi
<p>
<pre><div class="fragment"><pre>
#define COUNT_DOWN(N) BOOST_PP_WHILE(COUNT_DOWN_C,COUNT_DOWN_F,N)
// Above is the function we are implementing using BOOST_PP_WHILE().
// Above is the macro we are implementing using BOOST_PP_WHILE().
#define COUNT_DOWN_C(D,N) N
// Above is the Condition. It expands to the current N.
// Above is the condition. It expands to the current N.
#define COUNT_DOWN_F(D,N) BOOST_PP_DEC(N)
// Above is the iteration Function. It decrements N.
// Above is the iteration macro. It decrements N.
COUNT_DOWN(50)
// The above expands to 0.
@ -85,7 +85,7 @@ For a more complex example, let's take a look at an implementation of <a class="
<p>
<pre><div class="fragment"><pre>
#define BOOST_PP_MUL(X,Y) BOOST_PP_MUL_D(0,X,Y)
// Since the function is implemented using WHILE, the actual implementation
// Since the macro is implemented using WHILE, the actual implementation
// takes a depth as a parameter so that it can be called inside a WHILE.
// The above easy-to-use version simply uses 0 as the depth and can not be
// called inside a WHILE.
@ -101,7 +101,7 @@ For a more complex example, let's take a look at an implementation of <a class="
// #2) The WHILE primitive is "invoked" directly. BOOST_PP_WHILE(D,...)
// can't be used because it would not be expanded by the C preprocessor.
//
// #3) ???_C is the condition and ???_F is the iteration function.
// #3) ???_C is the condition and ???_F is the iteration macro.
#define BOOST_PP_MUL_C(D,P)\
BOOST_PP_TUPLE_ELEM(3,2,P)