Lookahead, positive and negative.

Raku · Oct 3, 2012 · 2d70bfa · 2d70bfa
1 parent 94286df
commit 2d70bfa
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diff --git a/src/QRegex/P5Regex/Actions.nqp b/src/QRegex/P5Regex/Actions.nqp
@@ -178,7 +178,35 @@ class QRegex::P5Regex::Actions is HLL::Actions {
                     QAST::SVal.new( :value(~$<number> - 1) ) ) );
         }
     }
+
+    method p5assertion:sym<=>($/) {
+        if $<nibbler> {
+            make QAST::Regex.new(
+                :rxtype<subrule>, :subtype<zerowidth>, :node($/),
+                QAST::Node.new(
+                    QAST::SVal.new( :value('before') ),
+                    qbuildsub($<nibbler>.ast, :anon(1), :addself(1))
+                ));
+        }
+        else {
+            make 0;
+        }
+    }
 
+    method p5assertion:sym<!>($/) {
+        if $<nibbler> {
+            make QAST::Regex.new(
+                :rxtype<subrule>, :subtype<zerowidth>, :negate(1), :node($/),
+                QAST::Node.new(
+                    QAST::SVal.new( :value('before') ),
+                    qbuildsub($<nibbler>.ast, :anon(1), :addself(1))
+                ));
+        }
+        else {
+            make 0;
+        }
+    }
+
     method p5mods($/) {
         for nqp::split('', ~$<on>) {
             %*RX{$_} := 1;

diff --git a/src/QRegex/P5Regex/Grammar.nqp b/src/QRegex/P5Regex/Grammar.nqp
@@ -88,6 +88,9 @@ grammar QRegex::P5Regex::Grammar is HLL::Grammar {
 
     proto token p5assertion { <...> }
 
+    token p5assertion:sym<=> { <sym> [ <?before ')'> | <nibbler> ] }
+    token p5assertion:sym<!> { <sym> [ <?before ')'> | <nibbler> ] }
+
     token p5mod  { <[imox]>* }
     token p5mods { <on=p5mod> [ '-' <off=p5mod> ]? }
     token p5assertion:sym<mod> {