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Diffstat (limited to 'docs/index.html')
| -rw-r--r-- | docs/index.html | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/docs/index.html b/docs/index.html index 4cd0d91..6da6a15 100644 --- a/docs/index.html +++ b/docs/index.html @@ -103,6 +103,7 @@ href="http://weitz.de/regex-coach/">The Regex Coach</a>. <li><a href="#*optimize-char-classes*"><code>*optimize-char-classes*</code></a> <li><a href="#*allow-quoting*"><code>*allow-quoting*</code></a> <li><a href="#*allow-named-registers*"><code>*allow-named-registers*</code></a> + <li><a href="#*look-ahead-for-suffix*"><code>*look-ahead-for-suffix*</code></a> </ol> <li><a href="#misc">Miscellaneous</a> <ol> @@ -1391,6 +1392,31 @@ to which value <code>*ALLOW-NAMED-REGISTERS*</code> is bound at that time.</blockquote> </blockquote> +<p><br>[Special variable] +<br><a class=none name="*look-ahead-for-suffix*"><b>*look-ahead-for-suffix*</b></a> + +<blockquote><br>Given a regular expression which has a constant +suffix, such as <code>(a|b)+x</code> whose constant suffix +is <code>x</code>, the scanners created +by <a href="#create-scanner"><code>CREATE-SCANNER</code></a> will +attempt to optimize by searching for the position of the suffix prior +to performing the full match. In many cases, this is an optimization, +especially when backtracking is involved on small strings. However, in +other cases, such as incremental parsing of a very large string, this +can cause a degradation in performance, because the entire string is +searched for the suffix before an otherwise easy prefix match failure +can occur. The variable <code>*LOOK-AHEAD-FOR-SUFFIX*</code>, whose +default is <code>T</code>, can be used to selectively control this +behavior. +<p> +Note: Due to the nature of <a href="http://www.lispworks.com/documentation/HyperSpec/Body/s_ld_tim.htm"><code>LOAD-TIME-VALUE</code></a> and the <a +href="#compiler-macro">compiler macro for <code>SCAN</code> and other functions</a>, some +scanners might be created in a <a +href="http://www.lispworks.com/documentation/HyperSpec/Body/26_glo_n.htm#null_lexical_environment">null +lexical environment</a> at load time or at compile time so be careful +to which value <code>*LOOK-AHEAD-FOR-SUFFIX*</code> is bound at that +time.</blockquote> + <h4><a name="misc" class=none>Miscellaneous</a></h4> <p><br>[Function] |