libxl: IDL: autogenerate functions to produce JSON from libxl data structures.

Two functions are provided. TYPE_gen_json exposes an interface which is
compatible with the YAGL generator infrastructure. TYPE_to_string uses this to
produce a pretty printed string.

The TYPE_gen_json functions are defined in a new header libxl_json.h which is
not exposed via libxl.h due to the use of YAGL datatypes to avoid poluting the
namespace us libxl users which don't use the library themselves.  If a libxl
user is interested in integrating at the YAGL level then it should #include
this file itself.

Also update testidl to generate a random version of each IDL datastructure and
convert it to JSON. Unfortunately this requires a libxl_ctx and therefore the
test must be run on a Xen system now.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson.citrix.com>
Committed-by: Ian Jackson <ian.jackson.citrix.com>

1 files changed, 96 insertions, 6 deletions

diff --git a/tools/libxl/gentypes.py b/tools/libxl/gentypes.py
index ecf5f152c4..e82b70673b 100644
--- a/tools/libxl/gentypes.py
+++ b/tools/libxl/gentypes.py
@@ -29,7 +29,6 @@ def libxl_C_instance_of(ty, instancename):
 
 def libxl_C_type_define(ty, indent = ""):
     s = ""
-
     if isinstance(ty, libxltypes.Enumeration):
         if ty.comment is not None:
             s += format_comment(0, ty.comment)
@@ -76,7 +75,6 @@ def libxl_C_type_define(ty, indent = ""):
     return s.replace("\n", "\n%s" % indent)
 
 def libxl_C_type_destroy(ty, v, indent = "    ", parent = None):
-
     s = ""
     if isinstance(ty, libxltypes.KeyedUnion):
         if parent is None:
@@ -100,6 +98,60 @@ def libxl_C_type_destroy(ty, v, indent = "    ", parent = None):
         s = indent + s
     return s.replace("\n", "\n%s" % indent).rstrip(indent)
 
+def libxl_C_type_gen_json(ty, v, indent = "    ", parent = None):
+    s = ""
+    if parent is None:
+        s += "yajl_gen_status s;\n"
+    if isinstance(ty, libxltypes.Enumeration):
+        s += "s = libxl__yajl_gen_enum(hand, %s_to_string(%s));\n" % (ty.typename, ty.pass_arg(v, parent is None))
+        s += "if (s != yajl_gen_status_ok)\n"
+        s += "    goto out;\n"
+    elif isinstance(ty, libxltypes.KeyedUnion):
+        if parent is None:
+            raise Exception("KeyedUnion type must have a parent")
+        s += "switch (%s) {\n" % (parent + ty.keyvar_name)
+        for f in ty.fields:
+            (nparent,fexpr) = ty.member(v, f, parent is None)
+            s += "case %s:\n" % f.enumname
+            s += libxl_C_type_gen_json(f.type, fexpr, indent + "    ", nparent)
+            s += "    break;\n"
+        s += "}\n"
+    elif isinstance(ty, libxltypes.Struct) and (parent is None or ty.json_fn is None):
+        s += "s = yajl_gen_map_open(hand);\n"
+        s += "if (s != yajl_gen_status_ok)\n"
+        s += "    goto out;\n"
+        for f in [f for f in ty.fields if not f.const]:
+            (nparent,fexpr) = ty.member(v, f, parent is None)
+            s += "s = yajl_gen_string(hand, (const unsigned char *)\"%s\", sizeof(\"%s\")-1);\n" % (f.name, f.name)
+            s += "if (s != yajl_gen_status_ok)\n"
+            s += "    goto out;\n"
+            s += libxl_C_type_gen_json(f.type, fexpr, "", nparent)
+        s += "s = yajl_gen_map_close(hand);\n"
+        s += "if (s != yajl_gen_status_ok)\n"
+        s += "    goto out;\n"
+    else:
+        if ty.json_fn is not None:
+            s += "s = %s(hand, %s);\n" % (ty.json_fn, ty.pass_arg(v, parent is None))
+            s += "if (s != yajl_gen_status_ok)\n"
+            s += "    goto out;\n"
+
+    if parent is None:
+        s += "out:\n"
+        s += "return s;\n"
+
+    if s != "":
+        s = indent + s
+    return s.replace("\n", "\n%s" % indent).rstrip(indent)
+
+def libxl_C_type_to_json(ty, v, indent = "    "):
+    s = ""
+    gen = "(libxl__gen_json_callback)&%s_gen_json" % ty.typename
+    s += "return libxl__object_to_json(ctx, \"%s\", %s, (void *)%s);\n" % (ty.typename, gen, ty.pass_arg(v, passby=libxltypes.PASS_BY_REFERENCE))
+
+    if s != "":
+        s = indent + s
+    return s.replace("\n", "\n%s" % indent).rstrip(indent)
+
 def libxl_C_enum_to_string(ty, e, indent = "    "):
     s = ""
     s += "switch(%s) {\n" % e
@@ -138,13 +190,13 @@ def libxl_C_enum_from_string(ty, str, e, indent = "    "):
 
 
 if __name__ == '__main__':
-    if len(sys.argv) != 4:
-        print >>sys.stderr, "Usage: gentypes.py <idl> <header> <implementation>"
+    if len(sys.argv) != 5:
+        print >>sys.stderr, "Usage: gentypes.py <idl> <header> <header-json> <implementation>"
         sys.exit(1)
 
-    (_, idl, header, impl) = sys.argv
+    (_, idl, header, header_json, impl) = sys.argv
 
-    (_,types) = libxltypes.parse(idl)
+    (builtins,types) = libxltypes.parse(idl)
 
     print "outputting libxl type definitions to %s" % header
 
@@ -167,6 +219,8 @@ if __name__ == '__main__':
         f.write(libxl_C_type_define(ty) + ";\n")
         if ty.destructor_fn is not None:
             f.write("void %s(%s);\n" % (ty.destructor_fn, ty.make_arg("p")))
+        if ty.json_fn is not None:
+            f.write("char *%s_to_json(libxl_ctx *ctx, %s);\n" % (ty.typename, ty.make_arg("p")))
         if isinstance(ty, libxltypes.Enumeration):
             f.write("const char *%s_to_string(%s);\n" % (ty.typename, ty.make_arg("p")))
             f.write("int %s_from_string(const char *s, %s);\n" % (ty.typename, ty.make_arg("e", passby=libxltypes.PASS_BY_REFERENCE)))
@@ -176,6 +230,30 @@ if __name__ == '__main__':
     f.write("""#endif /* %s */\n""" % (header_define))
     f.close()
 
+    print "outputting libxl JSON definitions to %s" % header_json
+
+    f = open(header_json, "w")
+
+    header_json_define = header_json.upper().replace('.','_')
+    f.write("""#ifndef %s
+#define %s
+
+/*
+ * DO NOT EDIT.
+ *
+ * This file is autogenerated by
+ * "%s"
+ */
+
+""" % (header_json_define, header_json_define, " ".join(sys.argv)))
+
+    for ty in [ty for ty in types+builtins if ty.json_fn is not None]:
+        f.write("yajl_gen_status %s_gen_json(yajl_gen hand, %s);\n" % (ty.typename, ty.make_arg("p", passby=libxltypes.PASS_BY_REFERENCE)))
+
+    f.write("\n")
+    f.write("""#endif /* %s */\n""" % header_json_define)
+    f.close()
+
     print "outputting libxl type implementations to %s" % impl
 
     f = open(impl, "w")
@@ -222,5 +300,17 @@ if __name__ == '__main__':
         f.write("}\n")
         f.write("\n")
 
+    for ty in [t for t in types if t.json_fn is not None]:
+        f.write("yajl_gen_status %s_gen_json(yajl_gen hand, %s)\n" % (ty.typename, ty.make_arg("p", passby=libxltypes.PASS_BY_REFERENCE)))
+        f.write("{\n")
+        f.write(libxl_C_type_gen_json(ty, "p"))
+        f.write("}\n")
+        f.write("\n")
+
+        f.write("char *%s_to_json(libxl_ctx *ctx, %s)\n" % (ty.typename, ty.make_arg("p")))
+        f.write("{\n")
+        f.write(libxl_C_type_to_json(ty, "p"))
+        f.write("}\n")
+        f.write("\n")
 
     f.close()