[gobject-introspection/ebassi/property-default-value: 2/2] Add an optional attribute for the property default value

[Emmanuele Bassi <ebassi src gnome org>]

commit a954af996da01f210983b94d4844bad95a419296
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Tue Aug 30 23:45:50 2022 +0100

    Add an optional attribute for the property default value
    
    The default-value attribute for a property element is fundamentally
    meant for documentation generators.
    
    We only care about the GIR data, as the conversion from the default
    value to a string is lossy by definition, and may very well not
    roundtrip.

 docs/gir-1.2.rnc                       |  2 +
 giscanner/ast.py                       |  1 +
 giscanner/gdumpparser.py               |  7 ++-
 giscanner/girparser.py                 |  1 +
 giscanner/girwriter.py                 |  2 +
 tests/scanner/Regress-1.0-expected.gir | 87 +++++++++++++++++++++++++---------
 6 files changed, 75 insertions(+), 25 deletions(-)
---
diff --git a/docs/gir-1.2.rnc b/docs/gir-1.2.rnc
index 10c6927c2..706cbea3d 100644
--- a/docs/gir-1.2.rnc
+++ b/docs/gir-1.2.rnc
@@ -350,6 +350,8 @@ grammar {
       attribute setter { xsd:string }?,
       ## The getter function for this property
       attribute getter { xsd:string }?,
+      ## The default value of the property, as a string; if missing, the default value is zero for integer 
types, and null for pointer types
+      attribute default-value { xsd:string }?,
       # Define the transfer of ownership of the property element
       TransferOwnership?,
 
diff --git a/giscanner/ast.py b/giscanner/ast.py
index 2cfd81fca..dac326cb7 100644
--- a/giscanner/ast.py
+++ b/giscanner/ast.py
@@ -1304,6 +1304,7 @@ class Property(Node):
             self.transfer = transfer
         self.setter = None
         self.getter = None
+        self.default_value = None
         self.parent = None  # A Class or Interface
 
 
diff --git a/giscanner/gdumpparser.py b/giscanner/gdumpparser.py
index 1a0794d42..21fbadf40 100644
--- a/giscanner/gdumpparser.py
+++ b/giscanner/gdumpparser.py
@@ -414,10 +414,13 @@ different --identifier-prefix.""" % (xmlnode.attrib['name'], self._namespace.ide
             writable = (flags & G_PARAM_WRITABLE) != 0
             construct = (flags & G_PARAM_CONSTRUCT) != 0
             construct_only = (flags & G_PARAM_CONSTRUCT_ONLY) != 0
-            node.properties.append(ast.Property(
+            default_value = pspec.attrib['default-value']
+            prop = ast.Property(
                 pspec.attrib['name'],
                 ast.Type.create_from_gtype_name(ctype),
-                readable, writable, construct, construct_only))
+                readable, writable, construct, construct_only)
+            prop.default_value = default_value
+            node.properties.append(prop)
         node.properties = node.properties
 
     def _introspect_signals(self, node, xmlnode):
diff --git a/giscanner/girparser.py b/giscanner/girparser.py
index edaaa9921..5fc228990 100644
--- a/giscanner/girparser.py
+++ b/giscanner/girparser.py
@@ -609,6 +609,7 @@ class GIRParser(object):
                             node.attrib.get('transfer-ownership'))
         prop.setter = node.attrib.get('setter')
         prop.getter = node.attrib.get('getter')
+        prop.default_value = node.attrib.get('default-value')
         prop.parent = parent
         self._parse_generic_attribs(node, prop)
         return prop
diff --git a/giscanner/girwriter.py b/giscanner/girwriter.py
index 9ff10d317..a3b3bc3ef 100644
--- a/giscanner/girwriter.py
+++ b/giscanner/girwriter.py
@@ -560,6 +560,8 @@ class GIRWriter(XMLWriter):
             attrs.append(('setter', prop.setter))
         if prop.getter:
             attrs.append(('getter', prop.getter))
+        if prop.default_value:
+            attrs.append(('default-value', prop.default_value))
         with self.tagcontext('property', attrs):
             self._write_generic(prop)
             self._write_type(prop.type)
diff --git a/tests/scanner/Regress-1.0-expected.gir b/tests/scanner/Regress-1.0-expected.gir
index 99d682713..0b5b4735b 100644
--- a/tests/scanner/Regress-1.0-expected.gir
+++ b/tests/scanner/Regress-1.0-expected.gir
@@ -1088,7 +1088,8 @@ regress_annotation_object_watch_full().</doc>
       <property name="function-property"
                 writable="1"
                 construct="1"
-                transfer-ownership="none">
+                transfer-ownership="none"
+                default-value="NULL">
         <type name="AnnotationCallback" c:type="gpointer"/>
       </property>
       <property name="string-property"
@@ -1097,7 +1098,8 @@ regress_annotation_object_watch_full().</doc>
                 deprecated-version="1.2"
                 writable="1"
                 construct="1"
-                transfer-ownership="none">
+                transfer-ownership="none"
+                default-value="NULL">
         <doc xml:space="preserve"
              filename="annotation.c"
              line="156">This is a property which is a string</doc>
@@ -1108,7 +1110,8 @@ regress_annotation_object_watch_full().</doc>
                 version="1.2"
                 writable="1"
                 construct="1"
-                transfer-ownership="none">
+                transfer-ownership="none"
+                default-value="NULL">
         <doc xml:space="preserve"
              filename="annotation.c"
              line="181">This is a property annotation intentionally indented with a mix
@@ -2144,13 +2147,15 @@ uses a C sugar return type.</doc>
                 introspectable="0"
                 writable="1"
                 construct-only="1"
-                transfer-ownership="none">
+                transfer-ownership="none"
+                default-value="NULL">
         <type/>
       </property>
       <property name="string"
                 writable="1"
                 construct="1"
-                transfer-ownership="none">
+                transfer-ownership="none"
+                default-value="NULL">
         <type name="utf8" c:type="gchar*"/>
       </property>
       <field name="parent_instance">
@@ -3912,7 +3917,8 @@ use it should be.</doc>
       <property name="number"
                 writable="1"
                 construct="1"
-                transfer-ownership="none">
+                transfer-ownership="none"
+                default-value="0">
         <type name="gint" c:type="gint"/>
       </property>
       <glib:signal name="interface-signal" when="last">
@@ -4834,30 +4840,47 @@ raise an error.</doc>
       <property name="bare"
                 writable="1"
                 transfer-ownership="none"
-                setter="set_bare">
+                setter="set_bare"
+                default-value="NULL">
         <type name="GObject.Object"/>
       </property>
-      <property name="boxed" writable="1" transfer-ownership="none">
+      <property name="boxed"
+                writable="1"
+                transfer-ownership="none"
+                default-value="NULL">
         <type name="TestBoxed"/>
       </property>
       <property name="byte-array"
                 writable="1"
                 construct="1"
-                transfer-ownership="none">
+                transfer-ownership="none"
+                default-value="NULL">
         <array name="GLib.ByteArray">
           <type name="guint8" c:type="guint8"/>
         </array>
       </property>
-      <property name="double" writable="1" transfer-ownership="none">
+      <property name="double"
+                writable="1"
+                transfer-ownership="none"
+                default-value="1.000000">
         <type name="gdouble" c:type="gdouble"/>
       </property>
-      <property name="float" writable="1" transfer-ownership="none">
+      <property name="float"
+                writable="1"
+                transfer-ownership="none"
+                default-value="1.000000">
         <type name="gfloat" c:type="gfloat"/>
       </property>
-      <property name="gtype" writable="1" transfer-ownership="none">
+      <property name="gtype"
+                writable="1"
+                transfer-ownership="none"
+                default-value="NULL">
         <type name="GType" c:type="GType"/>
       </property>
-      <property name="hash-table" writable="1" transfer-ownership="container">
+      <property name="hash-table"
+                writable="1"
+                transfer-ownership="container"
+                default-value="NULL">
         <type name="GLib.HashTable">
           <type name="utf8"/>
           <type name="gint8"/>
@@ -4865,21 +4888,31 @@ raise an error.</doc>
       </property>
       <property name="hash-table-old"
                 writable="1"
-                transfer-ownership="container">
+                transfer-ownership="container"
+                default-value="NULL">
         <type name="GLib.HashTable">
           <type name="utf8"/>
           <type name="gint8"/>
         </type>
       </property>
-      <property name="int" writable="1" transfer-ownership="none">
+      <property name="int"
+                writable="1"
+                transfer-ownership="none"
+                default-value="0">
         <type name="gint" c:type="gint"/>
       </property>
-      <property name="list" writable="1" transfer-ownership="none">
+      <property name="list"
+                writable="1"
+                transfer-ownership="none"
+                default-value="NULL">
         <type name="GLib.List" c:type="gpointer">
           <type name="utf8"/>
         </type>
       </property>
-      <property name="list-old" writable="1" transfer-ownership="none">
+      <property name="list-old"
+                writable="1"
+                transfer-ownership="none"
+                default-value="NULL">
         <type name="GLib.List" c:type="gpointer">
           <type name="utf8"/>
         </type>
@@ -4887,10 +4920,14 @@ raise an error.</doc>
       <property name="name-conflict"
                 writable="1"
                 construct="1"
-                transfer-ownership="none">
+                transfer-ownership="none"
+                default-value="42">
         <type name="gint" c:type="gint"/>
       </property>
-      <property name="pptrarray" writable="1" transfer-ownership="none">
+      <property name="pptrarray"
+                writable="1"
+                transfer-ownership="none"
+                default-value="NULL">
         <array name="GLib.PtrArray" c:type="gpointer">
           <type name="utf8"/>
         </array>
@@ -4899,13 +4936,15 @@ raise an error.</doc>
                 writable="1"
                 transfer-ownership="none"
                 setter="set_string"
-                getter="get_string">
+                getter="get_string"
+                default-value="NULL">
         <type name="utf8" c:type="gchar*"/>
       </property>
       <property name="write-only"
                 readable="0"
                 writable="1"
-                transfer-ownership="none">
+                transfer-ownership="none"
+                default-value="FALSE">
         <type name="gboolean" c:type="gboolean"/>
       </property>
       <field name="parent_instance">
@@ -5709,7 +5748,8 @@ the introspection client langage.</doc>
       <property name="boolean"
                 writable="1"
                 construct="1"
-                transfer-ownership="none">
+                transfer-ownership="none"
+                default-value="TRUE">
         <type name="gboolean" c:type="gboolean"/>
       </property>
       <field name="parent_instance">
@@ -5789,7 +5829,8 @@ the introspection client langage.</doc>
                 writable="1"
                 transfer-ownership="none"
                 setter="set_testbool"
-                getter="get_testbool">
+                getter="get_testbool"
+                default-value="TRUE">
         <type name="gboolean" c:type="gboolean"/>
       </property>
       <field name="parent_instance">