refactor!: Seal trait AIR

The pubic trait `AIR` used to be implementable downstream. This was
never intended. Now, by sealing the trait, downstream dependencies
cannot implement the trait.

triton-air/src/lib.rs

@@ -12,6 +12,10 @@ pub mod cross_table_argument;
 pub mod table;
 pub mod table_column;
 
+mod private {
+    pub trait Seal {}
+}
+
 /// The degree of the AIR after the degree lowering step.
 ///
 /// Using substitution and the introduction of new variables, the degree of the AIR as specified
@@ -28,7 +32,17 @@ pub mod table_column;
 /// The degree lowering happens in Triton VM's build script, `build.rs`.
 pub const TARGET_DEGREE: isize = 4;
 
-pub trait AIR {
+/// The main trait for the [tables]' Arithmetic Intermediate Representation.
+///
+/// This is a _sealed_ trait. It is not intended (or possible) to implement this
+/// trait outside the crate defining it.
+///
+/// [tables]: table::TableId
+///
+/// ### Object safety
+///
+/// This trait is _not_ object safe.
+pub trait AIR: private::Seal {
     type MainColumn: MasterMainColumn + EnumCount;
     type AuxColumn: MasterAuxColumn + EnumCount;
 

triton-air/src/table/cascade.rs

@@ -25,6 +25,8 @@ use crate::AIR;
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub struct CascadeTable;
 
+impl crate::private::Seal for CascadeTable {}
+
 impl AIR for CascadeTable {
     type MainColumn = crate::table_column::CascadeMainColumn;
     type AuxColumn = crate::table_column::CascadeAuxColumn;

triton-air/src/table/hash.rs

@@ -39,6 +39,8 @@ pub type PermutationTrace = [[BFieldElement; tip5::STATE_SIZE]; PERMUTATION_TRAC
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub struct HashTable;
 
+impl crate::private::Seal for HashTable {}
+
 type MainColumn = <HashTable as AIR>::MainColumn;
 type AuxColumn = <HashTable as AIR>::AuxColumn;
 

triton-air/src/table/jump_stack.rs

@@ -34,6 +34,8 @@ use crate::AIR;
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub struct JumpStackTable;
 
+impl crate::private::Seal for JumpStackTable {}
+
 impl AIR for JumpStackTable {
     type MainColumn = crate::table_column::JumpStackMainColumn;
     type AuxColumn = crate::table_column::JumpStackAuxColumn;

triton-air/src/table/lookup.rs

@@ -33,6 +33,8 @@ use crate::AIR;
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub struct LookupTable;
 
+impl crate::private::Seal for LookupTable {}
+
 impl AIR for LookupTable {
     type MainColumn = LookupMainColumn;
     type AuxColumn = LookupAuxColumn;

triton-air/src/table/op_stack.rs

@@ -27,6 +27,8 @@ pub const PADDING_VALUE: BFieldElement = BFieldElement::new(2);
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub struct OpStackTable;
 
+impl crate::private::Seal for OpStackTable {}
+
 impl AIR for OpStackTable {
     type MainColumn = crate::table_column::OpStackMainColumn;
     type AuxColumn = crate::table_column::OpStackAuxColumn;

triton-air/src/table/processor.rs

@@ -40,6 +40,8 @@ pub const NUM_HELPER_VARIABLE_REGISTERS: usize = 6;
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub struct ProcessorTable;
 
+impl crate::private::Seal for ProcessorTable {}
+
 type MainColumn = <ProcessorTable as AIR>::MainColumn;
 type AuxColumn = <ProcessorTable as AIR>::AuxColumn;
 

triton-air/src/table/program.rs

@@ -21,6 +21,8 @@ use crate::AIR;
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub struct ProgramTable;
 
+impl crate::private::Seal for ProgramTable {}
+
 impl AIR for ProgramTable {
     type MainColumn = crate::table_column::ProgramMainColumn;
     type AuxColumn = crate::table_column::ProgramAuxColumn;

triton-air/src/table/ram.rs

@@ -25,6 +25,8 @@ pub const PADDING_INDICATOR: BFieldElement = BFieldElement::new(2);
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub struct RamTable;
 
+impl crate::private::Seal for RamTable {}
+
 impl AIR for RamTable {
     type MainColumn = crate::table_column::RamMainColumn;
     type AuxColumn = crate::table_column::RamAuxColumn;

triton-air/src/table/u32.rs

@@ -22,6 +22,8 @@ use crate::AIR;
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub struct U32Table;
 
+impl crate::private::Seal for U32Table {}
+
 impl AIR for U32Table {
     type MainColumn = crate::table_column::U32MainColumn;
     type AuxColumn = crate::table_column::U32AuxColumn;