initial attempt at labels/goto. limitations: can't goto into/from a b…

…lock if the block declares lexicals; can't forward goto (will aim at fixing this soon)
Raku · May 12, 2012 · c98f22b · c98f22b
1 parent 17cc549
commit c98f22b
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Showing 3 changed files with 95 additions and 2 deletions.
diff --git a/src/NQP/Actions.pm b/src/NQP/Actions.pm
@@ -126,6 +126,30 @@ class NQP::Actions is HLL::Actions {
         make $past;
     }
 
+    method label($/) {
+        my $name := 'VNDUNVD84VN'~$<identifier>;
+        my $BLOCK := $*W.cur_lexpad();
+        if $BLOCK.symbol($name) {
+            $/.CURSOR.panic("Redeclaration of symbol ", $name);
+        }
+        $BLOCK.symbol($name, :scope('label') );
+        my $past := PAST::Label.new( :node($/), :name($name) );
+        make $past;
+    }
+
+    method goto($/) {
+        my $origname := $<identifier>;
+        my $name := 'VNDUNVD84VN'~$origname;
+        unless $*W.is_scope($name, 'label') {
+            $/.CURSOR.panic("missing label (no forward gotos) ", $origname);
+        }
+        my $past := PAST::Op.new(
+            :pasttype('goto'),
+            PAST::Label.new( :node($/), :name($name) )
+        );
+        make $past;
+    }
+
     method statement($/, $key?) {
         my $past;
         if $<EXPR> {
@@ -150,6 +174,15 @@ class NQP::Actions is HLL::Actions {
             }
         }
         elsif $<statement_control> { $past := $<statement_control>.ast; }
+        elsif $<label> {
+            $past := PAST::Stmts.new(
+                $<label>.ast,
+                $<statement>.ast
+            );
+        }
+        elsif $<goto> {
+            $past := $<goto>.ast;
+        }
         else { $past := 0; }
         make $past;
     }

diff --git a/src/NQP/Grammar.pm b/src/NQP/Grammar.pm
@@ -122,9 +122,20 @@ grammar NQP::Grammar is HLL::Grammar {
         | [<statement><.eat_terminator> ]*
     }
 
+    token label {
+        <identifier> ':' <?before \s> <.ws>
+    }
+
+    # not a real Perl 6 goto, so not a real &goto
+    token goto {
+        'goto' <?before \s> <.ws> <identifier>
+    }
+
     token statement {
         <!before <[\])}]> | $ >
         [
+        | <goto>
+        | <label> <statement>
         | <statement_control>
         | <EXPR> <.ws>
             [

diff --git a/src/PAST/NQP.pir b/src/PAST/NQP.pir
@@ -8,12 +8,63 @@
     base = get_hll_global ['PAST'], 'Node'
     p6meta.'new_class'('PAST::Want', 'parent'=>base)
     p6meta.'new_class'('PAST::QAST', 'parent'=>base)
+    p6meta.'new_class'('PAST::Label', 'parent'=>base)
 
     # add the nqp:: opcode map
     .const 'Sub' nqpmap = 'nqpmap'
     base.'map_add'('nqp', nqpmap)
 .end
 
+=head2 PAST::Label
+
+A C<PAST::Label> node stores the name of a label. It
+translates directly to a POST::Label.
+
+=cut 
+
+=item as_post(PAST::Label)
+
+Create the POST::Label.
+
+=cut
+
+.namespace ['PAST';'Compiler']
+
+.sub 'as_post' :method :multi(_, ['PAST';'Label'])
+    .param pmc node
+    .param pmc options         :slurpy :named
+
+    .local pmc label
+    .local string name
+    $P0 = get_hll_global ['POST'], 'Label'
+    name = node.'name'()
+    label = $P0.'new'('result'=>name)
+
+    .return (label)
+.end
+
+=item goto(PAST::Op)
+
+implement the goto pasttype
+
+=cut
+
+.sub 'goto' :method :multi(_, ['PAST';'Op'])
+    .param pmc node
+    .param pmc options         :slurpy :named
+
+    .local pmc lpast, ops, label
+    .local string name
+    lpast = node[0]
+    name = lpast.'name'()
+    $P0 = get_hll_global ['POST'], 'Ops'
+    ops = $P0.'new'('node'=>node)
+    $P0 = get_hll_global ['POST'], 'Label'
+    label = $P0.'new'('result'=>name)
+    ops.'push_pirop'('goto', label)
+
+    .return (ops)
+.end
 
 =head2 PAST::Want
 
@@ -37,8 +88,6 @@ Select a single past child based on rtype.
 
 =cut
 
-.namespace ['PAST';'Compiler']
-
 .sub 'as_post' :method :multi(_, ['PAST';'Want'])
     .param pmc node
     .param pmc options         :slurpy :named