[librsvg] rsvg_handle_rust_has_sub(): Port to Rust.

[Federico Mena Quintero <federico src gnome org>]

commit 999497014457faa4aeefe8c860b1dcc0a0aff033
Author: Federico Mena Quintero <federico gnome org>
Date:   Wed Dec 19 13:24:15 2018 -0600

    rsvg_handle_rust_has_sub(): Port to Rust.

 librsvg/rsvg-handle.c        | 16 +++-------------
 rsvg_internals/src/handle.rs | 20 ++++++++++++++++++++
 rsvg_internals/src/lib.rs    |  1 +
 3 files changed, 24 insertions(+), 13 deletions(-)
---
diff --git a/librsvg/rsvg-handle.c b/librsvg/rsvg-handle.c
index 965de1ac..6242f2d0 100644
--- a/librsvg/rsvg-handle.c
+++ b/librsvg/rsvg-handle.c
@@ -178,6 +178,7 @@ extern gboolean rsvg_handle_rust_get_geometry_sub (RsvgHandle *handle,
                                                    RsvgRectangle *out_ink_rect,
                                                    RsvgRectangle *out_logical_rect,
                                                    const char *id);
+extern gboolean rsvg_handle_rust_has_sub(RsvgHandle *handle, const char *id);
 
 /* Implemented in rust/src/node.rs */
 /* Call this as node = rsvg_node_unref (node);  Then node will be NULL and you don't own it anymore! */
@@ -1253,27 +1254,16 @@ rsvg_handle_get_position_sub (RsvgHandle * handle, RsvgPositionData * position_d
  * Since: 2.22
  */
 gboolean
-rsvg_handle_has_sub (RsvgHandle * handle,
+rsvg_handle_has_sub (RsvgHandle *handle,
                      const char *id)
 {
-    RsvgNode *node;
-    gboolean has_sub;
-
     g_return_val_if_fail (RSVG_IS_HANDLE (handle), FALSE);
 
     if (!is_loaded (handle)) {
         return FALSE;
     }
 
-    if (G_UNLIKELY (!id || !id[0]))
-      return FALSE;
-
-    node = rsvg_handle_defs_lookup (handle, id);
-    has_sub = node != NULL;
-
-    node = rsvg_node_unref (node);
-
-    return has_sub;
+    return rsvg_handle_rust_has_sub (handle, id);
 }
 
 /**
diff --git a/rsvg_internals/src/handle.rs b/rsvg_internals/src/handle.rs
index fa743b0a..5b7c47f6 100644
--- a/rsvg_internals/src/handle.rs
+++ b/rsvg_internals/src/handle.rs
@@ -363,6 +363,10 @@ impl Handle {
             _ => unreachable!(), // we explicitly requested a with_fragment after all
         }
     }
+
+    fn has_sub(&mut self, handle: *const RsvgHandle, name: &str) -> bool {
+        self.defs_lookup(handle, name).is_ok()
+    }
 }
 
 enum DefsLookupErrorKind {
@@ -858,3 +862,19 @@ pub unsafe extern "C" fn rsvg_handle_rust_get_geometry_sub(
         }
     }
 }
+
+#[no_mangle]
+pub unsafe extern "C" fn rsvg_handle_rust_has_sub(
+    handle: *mut RsvgHandle,
+    id: *const libc::c_char,
+) -> glib_sys::gboolean {
+    if id.is_null() {
+        false.to_glib()
+    } else {
+        let id: String = from_glib_none(id);
+
+        let rhandle = get_rust_handle(handle);
+
+        rhandle.has_sub(handle, &id).to_glib()
+    }
+}
diff --git a/rsvg_internals/src/lib.rs b/rsvg_internals/src/lib.rs
index 78531f7d..e55b35a7 100644
--- a/rsvg_internals/src/lib.rs
+++ b/rsvg_internals/src/lib.rs
@@ -48,6 +48,7 @@ pub use handle::{
     rsvg_handle_rust_get_flags,
     rsvg_handle_rust_get_geometry_sub,
     rsvg_handle_rust_get_load_state,
+    rsvg_handle_rust_has_sub,
     rsvg_handle_rust_new,
     rsvg_handle_rust_read_stream_sync,
     rsvg_handle_rust_set_base_url,