1 files changed, 126 insertions, 0 deletions
diff --git a/tools/python/xen/xend/Args.py b/tools/python/xen/xend/Args.py
new file mode 100644
index 0000000000..527e841d3d
--- /dev/null
+++ b/tools/python/xen/xend/Args.py
@@ -0,0 +1,126 @@
+import sxp
+
+class ArgError(StandardError):
+    pass
+
+class Args:
+    """Argument encoding support for HTTP.
+    """
+    
+    def __init__(self, paramspec, keyspec):
+        self.arg_ord = []
+        self.arg_dict = {}
+        self.key_ord = []
+        self.key_dict = {}
+        for (name, type) in paramspec:
+                self.arg_ord.append(name)
+                self.arg_dict[name] = type
+        for (name, type) in keyspec:
+                self.key_ord.append(name)
+                self.key_dict[name] = type
+
+    def get_args(self, d, xargs=None):
+        args = {}
+        keys = {}
+        params = []
+        if xargs:
+            self.split_args(xargs, args, keys)
+        self.split_args(d, args, keys)
+        for a in self.arg_ord:
+            if a in args:
+                params.append(args[a])
+            else:
+                raise ArgError('Missing parameter: %s' % a)
+        return (params, keys)
+
+    def split_args(self, d, args, keys):
+        for (k, v) in d.items():
+            if k in self.arg_dict:
+                type = self.arg_dict[k]
+                val = self.coerce(type, v)
+                args[k] = val
+            elif k in self.key_dict:
+                type = self.key_dict[k]
+                val = self.coerce(type, v)
+                keys[k] = val
+            else:
+                raise ArgError('Invalid parameter: %s' % k)
+
+    def get_form_args(self, f, xargs=None):
+        d = {}
+        for (k, v) in f.items():
+            n = len(v)
+            if ((k not in self.arg_dict) and
+                (k not in self.key_dict)):
+                continue
+            if n == 0:
+                continue
+            elif n == 1:
+                d[k] = v[0]
+            else:
+                raise ArgError('Too many values for %s' % k)
+        return self.get_args(d, xargs=xargs)
+
+    def coerce(self, type, v):
+        try:
+            if type == 'int':
+                return int(v)
+            if type == 'str':
+                return str(v)
+            if type == 'sxpr':
+                return self.sxpr(v)
+        except ArgError:
+            raise
+        except StandardError, ex:
+            raise ArgError(str(ex))
+
+    def sxpr(self, v):
+        if instanceof(v, types.ListType):
+            return v
+        if instanceof(v, types.File) or hasattr(v, 'readline'):
+            return sxpr_file(v)
+        if instanceof(v, types.StringType):
+            return sxpr_file(StringIO(v))
+        return str(v)
+
+    def sxpr_file(self, fin):
+        try:
+            vals = sxp.parse(fin)
+        except:
+            raise ArgError('Coercion to sxpr failed')
+        if len(vals) == 1:
+            return vals[0]
+        else:
+            raise ArgError('Too many sxprs')
+
+    def call_with_args(self, fn, args, xargs=None):
+        (params, keys) = self.get_args(args, xargs=xargs)
+        fn(*params, **keys)
+
+    def call_with_form_args(self, fn, fargs, xargs=None):
+        (params, keys) = self.get_form_args(fargs, xargs=xargs)
+        fn(*params, **keys)
+
+class ArgFn(Args):
+    """Represent a remote HTTP operation as a function.
+    Used on the client.
+    """
+
+    def __init__(self, fn, paramspec, keyspec={}):
+        Args.__init__(self, paramspec, keyspec)
+        self.fn = fn
+
+    def __call__(self, fargs, xargs=None):
+        return self.call_with_args(self.fn, fargs, xargs=xargs)
+    
+class FormFn(Args):
+    """Represent an operation as a function over a form.
+    Used in the HTTP server.
+    """
+
+    def __init__(self, fn, paramspec, keyspec={}):
+        Args.__init__(self, paramspec, keyspec)
+        self.fn = fn
+
+    def __call__(self, fargs, xargs=None):
+        return self.call_with_form_args(self.fn, fargs, xargs=xargs)