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Diffstat (limited to 'erts/doc/src')
| -rw-r--r-- | erts/doc/src/match_spec.xml | 75 |
1 files changed, 38 insertions, 37 deletions
diff --git a/erts/doc/src/match_spec.xml b/erts/doc/src/match_spec.xml index 3944f24f84..ca73d78b8d 100644 --- a/erts/doc/src/match_spec.xml +++ b/erts/doc/src/match_spec.xml @@ -528,7 +528,7 @@ </section> <section> - <title>ETS Examples</title> + <title>Tracing Examples</title> <p>Match an argument list of three where the first and third arguments are equal:</p> <code type="none"><![CDATA[ @@ -585,42 +585,6 @@ parameter list with a single variable is a special case. In all other cases the <c><![CDATA[MatchHead]]></c> has to be a <em>proper</em> list. </p> - <p>Match all objects in an ets table where the first element is - the atom 'strider' and the tuple arity is 3 and return the whole - object.</p> - <code type="none"><![CDATA[ -[{{strider,'_','_'}, - [], - ['$_']}] - ]]></code> - <p>Match all objects in an ets table with arity > 1 and the first - element is 'gandalf', return element 2.</p> - <code type="none"><![CDATA[ -[{'$1', - [{'==', gandalf, {element, 1, '$1'}},{'>=',{size, '$1'},2}], - [{element,2,'$1'}]}] - ]]></code> - <p>In the above example, if the first element had been the key, - it's much more efficient to match that key in the <c><![CDATA[MatchHead]]></c> - part than in the <c><![CDATA[MatchConditions]]></c> part. The search space of - the tables is restricted with regards to the <c><![CDATA[MatchHead]]></c> so - that only objects with the matching key are searched. - </p> - <p>Match tuples of 3 elements where the second element is either - 'merry' or 'pippin', return the whole objects.</p> - <code type="none"><![CDATA[ -[{{'_',merry,'_'}, - [], - ['$_']}, - {{'_',pippin,'_'}, - [], - ['$_']}] - ]]></code> - <p>The function <c><![CDATA[ets:test_ms/2]]></c> can be useful for testing - complicated ets matches.</p> - </section> - <section> - <title>Tracing Examples</title> <p>Only generate trace message if trace control word is set to 1:</p> <code type="none"><![CDATA[ [{'_', @@ -658,5 +622,42 @@ {'_',[],[]}] ]]></code> </section> + + <section> + <title>ETS Examples</title> + <p>Match all objects in an ets table where the first element is + the atom 'strider' and the tuple arity is 3 and return the whole + object.</p> + <code type="none"><![CDATA[ +[{{strider,'_','_'}, + [], + ['$_']}] + ]]></code> + <p>Match all objects in an ets table with arity > 1 and the first + element is 'gandalf', return element 2.</p> + <code type="none"><![CDATA[ +[{'$1', + [{'==', gandalf, {element, 1, '$1'}},{'>=',{size, '$1'},2}], + [{element,2,'$1'}]}] + ]]></code> + <p>In the above example, if the first element had been the key, + it's much more efficient to match that key in the <c><![CDATA[MatchHead]]></c> + part than in the <c><![CDATA[MatchConditions]]></c> part. The search space of + the tables is restricted with regards to the <c><![CDATA[MatchHead]]></c> so + that only objects with the matching key are searched. + </p> + <p>Match tuples of 3 elements where the second element is either + 'merry' or 'pippin', return the whole objects.</p> + <code type="none"><![CDATA[ +[{{'_',merry,'_'}, + [], + ['$_']}, + {{'_',pippin,'_'}, + [], + ['$_']}] + ]]></code> + <p>The function <c><![CDATA[ets:test_ms/2]]></c> can be useful for testing + complicated ets matches.</p> + </section> </chapter> |