From 568cc9b7c9f2316c79a57a9b12183ecbe9242ea0 Mon Sep 17 00:00:00 2001
From: pmichaud <pmichaud@pobox.com>
Date: Mon, 12 Oct 2009 23:05:46 -0500
Subject: [PATCH] Allow PAST::Regex subrule nodes to have arguments to pass to
 the subrule. Implement simple backreferences.

---
 src/PAST/Compiler-Regex.pir  | 12 ++++-----
 src/Regex/Cursor.pir         | 47 ++++++++++++++++++++++++++++++++++++
 src/Regex/P6Regex/Actions.pm |  4 +++
 3 files changed, 57 insertions(+), 6 deletions(-)

diff --git a/src/PAST/Compiler-Regex.pir b/src/PAST/Compiler-Regex.pir
index 5172720..9c8ce49 100644
--- a/src/PAST/Compiler-Regex.pir
+++ b/src/PAST/Compiler-Regex.pir
@@ -810,9 +810,9 @@ Perform a subrule call.
     name = self.'as_post'($P0, 'rtype'=>'*')
     ops.'push'(name)
 
-    .local pmc subpast, subpost
-    subpast = node[0]
-    subpost = self.'as_post'(subpast, 'rtype'=>'*')
+    .local pmc cpost, posargs, namedargs, subpost
+    (cpost, posargs, namedargs) = self.'post_children'(node, 'signature'=>'v:')
+    subpost = shift posargs
 
     .local pmc negate
     .local string testop
@@ -822,11 +822,11 @@ Perform a subrule call.
     .local pmc subtype
     subtype = node.'subtype'()
 
-    ops.'push_pirop'('inline', name, subtype, negate, 'inline'=>"  # rx subrule %0 subtype=%1 negate=%2")
+    ops.'push_pirop'('inline', subpost, subtype, negate, 'inline'=>"  # rx subrule %0 subtype=%1 negate=%2")
 
     self.'!cursorop'(ops, '!cursor_pos', 0, pos)
-    ops.'push'(subpost)
-    ops.'push_pirop'('callmethod', subpost, cur, 'result'=>'$P10')
+    ops.'push'(cpost)
+    ops.'push_pirop'('callmethod', subpost, cur, posargs :flat, namedargs :flat, 'result'=>'$P10')
     ops.'push_pirop'(testop, '$P10', fail)
     if subtype == 'zerowidth' goto done
     ops.'push_pirop'('callmethod', '"pos"', '$P10', 'result'=>pos)
diff --git a/src/Regex/Cursor.pir b/src/Regex/Cursor.pir
index 1de5777..5d7e2dc 100644
--- a/src/Regex/Cursor.pir
+++ b/src/Regex/Cursor.pir
@@ -721,6 +721,53 @@ Perform any action associated with the current regex match.
 .end
 
 
+=item !BACKREF(name)
+
+Match the backreference given by C<name>.
+
+=cut
+
+.sub '!BACKREF' :method
+    .param string name
+    .local pmc cur
+    .local int pos, eos
+    .local string tgt
+    (cur, pos, tgt) = self.'!cursor_start'()
+
+    # search the cursor cstack for the latest occurrence of C<name>
+    .local pmc cstack
+    cstack = getattribute self, '@!cstack'
+    if null cstack goto pass
+    .local int cstack_it
+    cstack_it = elements cstack
+  cstack_loop:
+    dec cstack_it
+    unless cstack_it >= 0 goto pass
+    .local pmc subcur
+    subcur = cstack[cstack_it]
+    $P0 = getattribute subcur, '$!names'
+    if null $P0 goto cstack_loop
+    $S0 = $P0
+    if name != $S0 goto cstack_loop
+    # we found a matching subcursor, get the literal it matched
+  cstack_done:
+    .local int litlen
+    .local string litstr
+    $I1 = subcur.'pos'()
+    $I0 = subcur.'from'()
+    litlen = $I1 - $I0
+    litstr = substr tgt, $I0, litlen
+    # now test the literal against our target
+    $S0 = substr tgt, pos, litlen
+    unless $S0 == litstr goto fail
+    pos += litlen
+  pass:
+    cur.'!cursor_pass'(pos, '')
+  fail:
+    .return (cur)
+.end
+
+
 =back
 
 =head2 Vtable functions
diff --git a/src/Regex/P6Regex/Actions.pm b/src/Regex/P6Regex/Actions.pm
index de090dd..6f91e25 100644
--- a/src/Regex/P6Regex/Actions.pm
+++ b/src/Regex/P6Regex/Actions.pm
@@ -178,6 +178,10 @@ method metachar:sym<var>($/) {
             $past.name($name); 
         }
     }
+    else {
+        $past := PAST::Regex.new( '!BACKREF', $name, :pasttype('subrule'),
+                                  :subtype('method') );
+    }
     make $past;
 }