Move Liftable to crate::abstract module

The `Liftable` trait is its own thing, it defines a trait to lift
miniscript, descriptors, and concrete policies to an abstract policy.

Move the `Liftable` and associated error type and impls to a new `lift`
module that lives under the recently created `crate::r#abstract` module.

Note we alse remove the `Semantic` and `Concrete` public
re-names/re-exports from `crate::policy` because we are transitioning
away from using the term "semantic", however to minimise the changes in
this patch we add a bunch of

  `use crate::policy::concrete::Policy as Concrete`

statements.

Author: tcharding

examples/htlc.rs

@@ -7,7 +7,8 @@ use std::str::FromStr;
 
 use miniscript::bitcoin::Network;
 use miniscript::descriptor::Wsh;
-use miniscript::policy::{Concrete, Liftable};
+use miniscript::policy::concrete::Policy as Concrete;
+use miniscript::r#abstract::Liftable;
 
 fn main() {
     // HTLC policy with 10:1 odds for happy (co-operative) case compared to uncooperative case.

examples/taproot.rs

@@ -8,7 +8,7 @@ use miniscript::bitcoin::key::{KeyPair, XOnlyPublicKey};
 use miniscript::bitcoin::secp256k1::rand;
 use miniscript::bitcoin::Network;
 use miniscript::descriptor::DescriptorType;
-use miniscript::policy::Concrete;
+use miniscript::policy::concrete::Policy as Concrete;
 use miniscript::{translate_hash_fail, Descriptor, Miniscript, Tap, TranslatePk, Translator};
 
 // Refer to https://github.com/sanket1729/adv_btc_workshop/blob/master/workshop.md#creating-a-taproot-descriptor

fuzz/fuzz_targets/compile_descriptor.rs

@@ -1,11 +1,11 @@
 use std::str::FromStr;
 
 use honggfuzz::fuzz;
+use miniscript::r#abstract::Liftable;
 use miniscript::{policy, Miniscript, Segwitv0};
-use policy::Liftable;
 
 type Script = Miniscript<String, Segwitv0>;
-type Policy = policy::Concrete<String>;
+type Policy = policy::concrete::Policy<String>;
 
 fn do_test(data: &[u8]) {
     let data_str = String::from_utf8_lossy(data);

fuzz/fuzz_targets/roundtrip_concrete.rs

@@ -4,7 +4,7 @@ use honggfuzz::fuzz;
 use miniscript::policy;
 use regex::Regex;
 
-type Policy = policy::Concrete<String>;
+type Policy = policy::concrete::Policy<String>;
 
 fn do_test(data: &[u8]) {
     let data_str = String::from_utf8_lossy(data);

fuzz/fuzz_targets/roundtrip_semantic.rs

@@ -3,7 +3,7 @@ use std::str::FromStr;
 use honggfuzz::fuzz;
 use miniscript::policy;
 
-type Policy = policy::Semantic<String>;
+type Policy = policy::r#abstract::Policy<String>;
 
 fn do_test(data: &[u8]) {
     let data_str = String::from_utf8_lossy(data);

src/abstract/lift.rs

@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: CC0-1.0
+
+//! WIP - TODO: Describe this module.
+
+pub use self::lift::{LiftError, Liftable};
+
+mod lift;

src/abstract/mod.rs

@@ -18,8 +18,9 @@ use crate::expression::{self, FromTree};
 use crate::miniscript::context::{ScriptContext, ScriptContextError};
 use crate::miniscript::satisfy::{Placeholder, Satisfaction, Witness};
 use crate::plan::AssetProvider;
-use crate::policy::{r#abstract, Liftable};
+use crate::policy::r#abstract;
 use crate::prelude::*;
+use crate::r#abstract::Liftable;
 use crate::util::{varint_len, witness_to_scriptsig};
 use crate::{
     BareCtx, Error, ForEachKey, Miniscript, MiniscriptKey, Satisfier, ToPublicKey, TranslateErr,

src/descriptor/bare.rs

@@ -1154,7 +1154,6 @@ mod test {
     use serde_test::{assert_tokens, Token};
 
     use super::*;
-    use crate::prelude::*;
 
     #[test]
     fn parse_descriptor_key_errors() {

src/descriptor/key.rs

@@ -16,8 +16,9 @@ use crate::expression::{self, FromTree};
 use crate::miniscript::context::{ScriptContext, ScriptContextError};
 use crate::miniscript::satisfy::{Placeholder, Satisfaction, Witness};
 use crate::plan::AssetProvider;
-use crate::policy::{r#abstract, Liftable};
+use crate::policy::r#abstract;
 use crate::prelude::*;
+use crate::r#abstract::Liftable;
 use crate::util::varint_len;
 use crate::{
     Error, ForEachKey, Miniscript, MiniscriptKey, Satisfier, Segwitv0, ToPublicKey, TranslateErr,