First iteration of circuits naming convention

book/src/anchoredkeys.md

@@ -6,6 +6,8 @@ type AnchoredKey = (Origin, Key)
 type Key = String
 ```
 
+FIXME: This description is incorrect.  We don't have *gadget ID*.  And we don't think of *origin* as a triple, we just see it as a single value that encodes the *pod ID* or SELF.
+
 An *origin* is a triple consisting of a numeric identifier called the *origin ID*, a string called the *origin name* (omitted in the backend) and another numeric identifier called the *gadget ID*, which identifies the means by which the value corresponding to a given key is produced.
 
 The origin ID is defined to be 0 for 'no origin' and 1 for 'self origin', otherwise it is the content ID[^content-id] of the POD to which it refers. The origin name is not cryptographically significant and is merely a convenience for the frontend.
@@ -19,4 +21,4 @@ The gadget ID takes on the values in the following table:
 | 2         | `MainPOD` gadget: The key-value pair was produced in the construction of a `MainPOD`.     |
 
 For example, a gadget ID of 1 implies that the key-value pair in question was produced in the process of constructing a `SignedPOD`.
-[^content-id]: <font color="red">TODO</font> Refer to this when it is documented.
+[^content-id]: <font color="red">TODO</font> Refer to this when it is documented.

src/backends/plonky2/circuits/common.rs

@@ -579,10 +579,22 @@ pub struct CustomPredicateVerifyEntryTarget {
     pub custom_predicate_table_index: Target,
     pub custom_predicate: CustomPredicateEntryTarget,
     pub args: Vec<ValueTarget>,
-    pub query: CustomPredicateVerifyQueryTarget,
+    pub op_args: Vec<StatementTarget>,
 }
 
 impl CustomPredicateVerifyEntryTarget {
+    pub fn new_virtual(params: &Params, builder: &mut CircuitBuilder) -> Self {
+        CustomPredicateVerifyEntryTarget {
+            custom_predicate_table_index: builder.add_virtual_target(),
+            custom_predicate: builder.add_virtual_custom_predicate_entry(params),
+            args: (0..params.max_custom_predicate_wildcards)
+                .map(|_| builder.add_virtual_value())
+                .collect(),
+            op_args: (0..params.max_operation_args)
+                .map(|_| builder.add_virtual_statement(params))
+                .collect(),
+        }
+    }
     pub fn set_targets(
         &self,
         pw: &mut PartialWitness<F>,
@@ -606,7 +618,7 @@ impl CustomPredicateVerifyEntryTarget {
             arg_target.set_targets(pw, &Value::from(arg.raw()))?;
         }
         let pad_op_arg = Statement(Predicate::Native(NativePredicate::None), vec![]);
-        for (op_arg_target, op_arg) in self.query.op_args.iter().zip_eq(
+        for (op_arg_target, op_arg) in self.op_args.iter().zip_eq(
             cpv.op_args
                 .iter()
                 .chain(iter::repeat(&pad_op_arg))