mingw/info/gdb/M2-Operators.html

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  12 Node:<a name="M2%20Operators">M2 Operators</a>,
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  18 <h5 class="subsubsection">Operators</h5>
  19
  20    <p>Operators must be defined on values of specific types.  For instance,
  21 <code>+</code> is defined on numbers, but not on structures.  Operators are
  22 often defined on groups of types.  For the purposes of Modula-2, the
  23 following definitions hold:
  24
  25      <ul>
  26
  27      <li><em>Integral types</em> consist of <code>INTEGER</code>, <code>CARDINAL</code>, and
  28 their subranges.
  29
  30      <li><em>Character types</em> consist of <code>CHAR</code> and its subranges.
  31
  32      <li><em>Floating-point types</em> consist of <code>REAL</code>.
  33
  34      <li><em>Pointer types</em> consist of anything declared as <code>POINTER TO
  35 </code><var>type</var><code></code>.
  36
  37      <li><em>Scalar types</em> consist of all of the above.
  38
  39      <li><em>Set types</em> consist of <code>SET</code> and <code>BITSET</code> types.
  40
  41      <li><em>Boolean types</em> consist of <code>BOOLEAN</code>.
  42 </ul>
  43
  44 <p>The following operators are supported, and appear in order of
  45 increasing precedence:
  46
  47      <dl>
  48 <dt><code>,</code>
  49      <dd>Function argument or array index separator.
  50
  51      <br><dt><code>:=</code>
  52      <dd>Assignment.  The value of <var>var</var> <code>:=</code> <var>value</var> is
  53 <var>value</var>.
  54
  55      <br><dt><code>&lt;</code>, <code>&gt;</code>
  56      <dd>Less than, greater than on integral, floating-point, or enumerated
  57 types.
  58
  59      <br><dt><code>&lt;=</code>, <code>&gt;=</code>
  60      <dd>Less than or equal to, greater than or equal to
  61 on integral, floating-point and enumerated types, or set inclusion on
  62 set types.  Same precedence as <code>&lt;</code>.
  63
  64      <br><dt><code>=</code>, <code>&lt;&gt;</code>, <code>#</code>
  65      <dd>Equality and two ways of expressing inequality, valid on scalar types.
  66 Same precedence as <code>&lt;</code>.  In GDB scripts, only <code>&lt;&gt;</code> is
  67 available for inequality, since <code>#</code> conflicts with the script
  68 comment character.
  69
  70      <br><dt><code>IN</code>
  71      <dd>Set membership.  Defined on set types and the types of their members.
  72 Same precedence as <code>&lt;</code>.
  73
  74      <br><dt><code>OR</code>
  75      <dd>Boolean disjunction.  Defined on boolean types.
  76
  77      <br><dt><code>AND</code>, <code>&amp;</code>
  78      <dd>Boolean conjunction.  Defined on boolean types.
  79
  80      <br><dt><code>@</code>
  81      <dd>The GDB "artificial array" operator (see <a href="Expressions.html#Expressions">Expressions</a>).
  82
  83      <br><dt><code>+</code>, <code>-</code>
  84      <dd>Addition and subtraction on integral and floating-point types, or union
  85 and difference on set types.
  86
  87      <br><dt><code>*</code>
  88      <dd>Multiplication on integral and floating-point types, or set intersection
  89 on set types.
  90
  91      <br><dt><code>/</code>
  92      <dd>Division on floating-point types, or symmetric set difference on set
  93 types.  Same precedence as <code>*</code>.
  94
  95      <br><dt><code>DIV</code>, <code>MOD</code>
  96      <dd>Integer division and remainder.  Defined on integral types.  Same
  97 precedence as <code>*</code>.
  98
  99      <br><dt><code>-</code>
 100      <dd>Negative. Defined on <code>INTEGER</code> and <code>REAL</code> data.
 101
 102      <br><dt><code>^</code>
 103      <dd>Pointer dereferencing.  Defined on pointer types.
 104
 105      <br><dt><code>NOT</code>
 106      <dd>Boolean negation.  Defined on boolean types.  Same precedence as
 107 <code>^</code>.
 108
 109      <br><dt><code>.</code>
 110      <dd><code>RECORD</code> field selector.  Defined on <code>RECORD</code> data.  Same
 111 precedence as <code>^</code>.
 112
 113      <br><dt><code>[]</code>
 114      <dd>Array indexing.  Defined on <code>ARRAY</code> data.  Same precedence as <code>^</code>.
 115
 116      <br><dt><code>()</code>
 117      <dd>Procedure argument list.  Defined on <code>PROCEDURE</code> objects.  Same precedence
 118 as <code>^</code>.
 119
 120      <br><dt><code>::</code>, <code>.</code>
 121      <dd>GDB and Modula-2 scope operators.
 122 </dl>
 123
 124    <blockquote>
 125 <em>Warning:</em> Sets and their operations are not yet supported, so GDB
 126 treats the use of the operator <code>IN</code>, or the use of operators
 127 <code>+</code>, <code>-</code>, <code>*</code>, <code>/</code>, <code>=</code>, , <code>&lt;&gt;</code>, <code>#</code>,
 128 <code>&lt;=</code>, and <code>&gt;=</code> on sets as an error.
 129 </blockquote>
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