refactor: move proof pieces used by ProofExprs and ProofPlans to …

…`proof_gadgets` (#433)

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# Rationale for this change
Bitwise verification, sign checks, range checks, subset checks,
uniqueness checks etc are building blocks of `ProofExpr`s and
`ProofPlan`s but are not themselves either. Hence we would like to put
them in a separate `proof_gadgets` directory.
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# What changes are included in this PR?
Move bitwise verification, sign checks & range checks to `proof_gadgets`
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# Are these changes tested?
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Existing tests do pass

crates/proof-of-sql/src/sql/mod.rs

@@ -3,4 +3,5 @@ pub mod parse;
 pub mod postprocessing;
 pub mod proof;
 pub mod proof_exprs;
+pub mod proof_gadgets;
 pub mod proof_plans;

crates/proof-of-sql/src/sql/proof_exprs/inequality_expr.rs

@@ -1,8 +1,7 @@
 use super::{
-    prover_evaluate_equals_zero, prover_evaluate_or, prover_evaluate_sign,
-    result_evaluate_equals_zero, result_evaluate_or, result_evaluate_sign,
-    scale_and_add_subtract_eval, scale_and_subtract, verifier_evaluate_equals_zero,
-    verifier_evaluate_or, verifier_evaluate_sign, DynProofExpr, ProofExpr,
+    prover_evaluate_equals_zero, prover_evaluate_or, result_evaluate_equals_zero,
+    result_evaluate_or, scale_and_add_subtract_eval, scale_and_subtract,
+    verifier_evaluate_equals_zero, verifier_evaluate_or, DynProofExpr, ProofExpr,
 };
 use crate::{
     base::{
@@ -11,7 +10,10 @@ use crate::{
         proof::ProofError,
         scalar::Scalar,
     },
-    sql::proof::{FinalRoundBuilder, VerificationBuilder},
+    sql::{
+        proof::{FinalRoundBuilder, VerificationBuilder},
+        proof_gadgets::{prover_evaluate_sign, result_evaluate_sign, verifier_evaluate_sign},
+    },
     utils::log,
 };
 use alloc::boxed::Box;

crates/proof-of-sql/src/sql/proof_exprs/mod.rs

@@ -20,11 +20,6 @@ use multiply_expr::MultiplyExpr;
 #[cfg(all(test, feature = "blitzar"))]
 mod multiply_expr_test;
 
-mod bitwise_verification;
-use bitwise_verification::{verify_constant_abs_decomposition, verify_constant_sign_decomposition};
-#[cfg(test)]
-mod bitwise_verification_test;
-
 mod dyn_proof_expr;
 pub(crate) use dyn_proof_expr::DynProofExpr;
 
@@ -69,11 +64,6 @@ use equals_expr::{
 #[cfg(all(test, feature = "blitzar"))]
 mod equals_expr_test;
 
-mod sign_expr;
-use sign_expr::{prover_evaluate_sign, result_evaluate_sign, verifier_evaluate_sign};
-#[cfg(all(test, feature = "blitzar"))]
-mod sign_expr_test;
-
 mod table_expr;
 pub(crate) use table_expr::TableExpr;
 

crates/proof-of-sql/src/sql/proof_gadgets/mod.rs

@@ -0,0 +1,12 @@
+//! This module contains shared proof logic for multiple `ProofExpr` / `ProofPlan` implementations.
+mod bitwise_verification;
+use bitwise_verification::{verify_constant_abs_decomposition, verify_constant_sign_decomposition};
+#[cfg(test)]
+mod bitwise_verification_test;
+mod sign_expr;
+pub(crate) use sign_expr::{prover_evaluate_sign, result_evaluate_sign, verifier_evaluate_sign};
+pub mod range_check;
+#[cfg(all(test, feature = "blitzar"))]
+pub mod range_check_test;
+#[cfg(all(test, feature = "blitzar"))]
+mod sign_expr_test;

crates/proof-of-sql/src/sql/proof_plans/range_check.rs → crates/proof-of-sql/src/sql/proof_gadgets/range_check.rs

@@ -403,12 +403,10 @@ where
 
 #[cfg(test)]
 mod tests {
+    use super::*;
     use crate::{
         base::scalar::{Curve25519Scalar as S, Scalar},
-        sql::{
-            proof::FinalRoundBuilder,
-            proof_plans::range_check::{decompose_scalar_to_words, get_logarithmic_derivative},
-        },
+        sql::proof::FinalRoundBuilder,
     };
     use bumpalo::Bump;
     use num_traits::Inv;

crates/proof-of-sql/src/sql/proof_plans/range_check_test_plan.rs → crates/proof-of-sql/src/sql/proof_gadgets/range_check_test.rs

@@ -92,15 +92,13 @@ impl ProofPlan for RangeCheckTestPlan {
 
 #[cfg(all(test, feature = "blitzar"))]
 mod tests {
-
+    use super::*;
     use crate::{
         base::database::{
             owned_table_utility::{owned_table, scalar},
             ColumnRef, ColumnType, OwnedTableTestAccessor,
         },
-        sql::{
-            proof::VerifiableQueryResult, proof_plans::range_check_test_plan::RangeCheckTestPlan,
-        },
+        sql::proof::VerifiableQueryResult,
     };
     use blitzar::proof::InnerProductProof;
 

crates/proof-of-sql/src/sql/proof_plans/mod.rs

@@ -50,7 +50,3 @@ pub use dyn_proof_plan::DynProofPlan;
 
 #[cfg(test)]
 mod demo_mock_plan;
-
-pub mod range_check;
-#[cfg(all(test, feature = "blitzar"))]
-pub mod range_check_test_plan;