ParseXS: refactor: add Node::INPUT_line fields

This is #7 of a small series of commits to refactor INPUT keyword
handling.

The main job of parsing an INPUT line is to extract any information on
that line and use it to update the associated Param object (which was
likely created earlier when the XSUB's signature was parsed).

This commit makes that information also be stored in new fields in the
INPUT_line object. These new fields aren't currently used for anything,
but they could in principle become useful if options for deparsing or
exporting were added to ParseXS.

Author: iabyn

dist/ExtUtils-ParseXS/lib/ExtUtils/ParseXS/Node.pm

@@ -2294,11 +2294,35 @@ package ExtUtils::ParseXS::Node::INPUT_line;
 # Handle one line from an INPUT keyword block
 
 BEGIN { $build_subclass->('keyline', # parent
-    'param', # the param object associated with this INPUT line.
+    'param',   # The Param object associated with this INPUT line.
+
+               # The parsed components of this INPUT line:
+    'type',    #   char *
+    'is_addr', #           &
+    'name',    #            foo
+    'init_op', #                =
+    'init',    #                   SvIv($arg)
 )};
 
 
-# Parse one line from an INPUT block
+# Parse one line in an INPUT block. This method does two main things:
+#
+# It parses the line and stores its components in the fields of the
+# INPUT_line object (which aren't further used for parsing or code
+# generation)
+#
+# It also uses those values to create/update the Param object
+# associated with this variable. For example with
+#
+#    void
+#    foo(a = 0)
+#       int a
+#
+# a Param object will already have been created with the name 'a' and
+# default value '0' when the signature was parsed. Parsing the 'int a'
+# line will set the INPUT_line object's fields to (type => 'int',
+# name => 'a'), while the Param object will have its type field set to
+# 'int'. The INPUT_line object also stores a ref to the Param object.
 #
 
 sub parse {
@@ -2366,7 +2390,6 @@ sub parse {
     my ExtUtils::ParseXS::Node::Param $param
                 = $pxs->{xsub_sig}{names}{$var_name};
 
-
     if (defined $param) {
         # The var appeared in the signature too.
 
@@ -2424,7 +2447,7 @@ sub parse {
     my $no_init = $param->{no_init}; # may have had OUT in signature
 
     if (!$no_init && defined $init_op) {
-        # Emit the init code based on overridden $var_init, which was
+        # Use the init code based on overridden $var_init, which was
         # preceded by /[=;+]/ which has been extracted into $init_op
 
         if (    $init_op =~ /^[=;]$/
@@ -2458,6 +2481,18 @@ sub parse {
         $no_init = 1 if $is_alien;
     }
 
+    # Save the basic information parsed from this line
+
+    $self->{type}    = $var_type,
+    $self->{is_addr} = !!$var_addr,
+    $self->{name}    = $var_name,
+    $self->{init_op} = $init_op,
+    $self->{init}    = $var_init,
+
+    $self->{param}   = $param;
+
+    # and also update the param object using that information
+
     %$param = (
         %$param,
         type    => $var_type,
@@ -2470,8 +2505,6 @@ sub parse {
         is_addr => !!$var_addr,
     );
 
-    $self->{param} = $param;
-
     $param->check($pxs)
         or return;
 }