Select builtins hint #1: enter scope (#35)

vm/src/hint_processor/builtin_hint_processor/bootloader/mod.rs

@@ -4,6 +4,7 @@ mod fact_topologies;
 pub(crate) mod inner_select_builtins;
 mod program_hash;
 mod program_loader;
+pub(crate) mod select_builtins;
 pub(crate) mod simple_bootloader_hints;
 pub(crate) mod types;
 pub(crate) mod vars;

vm/src/hint_processor/builtin_hint_processor/bootloader/select_builtins.rs

@@ -0,0 +1,72 @@
+use num_traits::ToPrimitive;
+use std::any::Any;
+use std::collections::HashMap;
+
+use crate::hint_processor::builtin_hint_processor::bootloader::vars;
+use crate::hint_processor::builtin_hint_processor::hint_utils::get_integer_from_var_name;
+use crate::hint_processor::hint_processor_definition::HintReference;
+use crate::serde::deserialize_program::ApTracking;
+use crate::types::errors::math_errors::MathError;
+use crate::types::exec_scope::ExecutionScopes;
+use crate::vm::errors::hint_errors::HintError;
+use crate::vm::vm_core::VirtualMachine;
+
+/// Implements
+/// %{ vm_enter_scope({'n_selected_builtins': ids.n_selected_builtins}) %}
+pub fn select_builtins_enter_scope(
+    vm: &mut VirtualMachine,
+    exec_scopes: &mut ExecutionScopes,
+    ids_data: &HashMap<String, HintReference>,
+    ap_tracking: &ApTracking,
+) -> Result<(), HintError> {
+    let n_selected_builtins =
+        get_integer_from_var_name(vars::N_SELECTED_BUILTINS, vm, ids_data, ap_tracking)?
+            .into_owned();
+    let n_selected_builtins =
+        n_selected_builtins
+            .to_usize()
+            .ok_or(MathError::Felt252ToUsizeConversion(Box::new(
+                n_selected_builtins,
+            )))?;
+
+    exec_scopes.enter_scope(HashMap::from([(
+        vars::N_SELECTED_BUILTINS.to_string(),
+        Box::new(n_selected_builtins) as Box<dyn Any>,
+    )]));
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::hint_processor::hint_processor_definition::HintReference;
+    use crate::types::exec_scope::ExecutionScopes;
+    use crate::utils::test_utils::*;
+    use crate::vm::vm_core::VirtualMachine;
+
+    use super::*;
+
+    #[test]
+    fn test_select_builtins_enter_scope() {
+        let mut vm = vm!();
+        // Set n_selected_builtins to 7
+        vm.run_context.fp = 1;
+        vm.segments = segments![((1, 0), 7)];
+        let ids_data = ids_data![vars::N_SELECTED_BUILTINS];
+        let n_selected_builtins = 7usize;
+
+        let ap_tracking = ApTracking::default();
+        let mut exec_scopes = ExecutionScopes::new();
+
+        select_builtins_enter_scope(&mut vm, &mut exec_scopes, &ids_data, &ap_tracking)
+            .expect("Hint failed unexpectedly");
+
+        // Check that we entered a new scope
+        assert_eq!(exec_scopes.data.len(), 2);
+        assert_eq!(exec_scopes.data[1].len(), 1);
+
+        let n_selected_builtins_var: usize = exec_scopes.get(vars::N_SELECTED_BUILTINS).unwrap();
+
+        assert_eq!(n_selected_builtins_var, n_selected_builtins);
+    }
+}

vm/src/hint_processor/builtin_hint_processor/builtin_hint_processor_definition.rs

@@ -33,6 +33,7 @@ use crate::hint_processor::builtin_hint_processor::bootloader::execute_task_hint
     write_return_builtins_hint,
 };
 use crate::hint_processor::builtin_hint_processor::bootloader::inner_select_builtins::select_builtin;
+use crate::hint_processor::builtin_hint_processor::bootloader::select_builtins::select_builtins_enter_scope;
 use crate::hint_processor::builtin_hint_processor::bootloader::simple_bootloader_hints::{
     divide_num_by_2, prepare_task_range_checks, set_ap_to_zero, set_current_task,
     set_tasks_variable,
@@ -921,6 +922,12 @@ impl HintProcessorLogic for BuiltinHintProcessor {
             hint_code::INNER_SELECT_BUILTINS_SELECT_BUILTIN => {
                 select_builtin(vm, exec_scopes, &hint_data.ids_data, &hint_data.ap_tracking)
             }
+            hint_code::SELECT_BUILTINS_ENTER_SCOPE => select_builtins_enter_scope(
+                vm,
+                exec_scopes,
+                &hint_data.ids_data,
+                &hint_data.ap_tracking,
+            ),
             #[cfg(feature = "skip_next_instruction_hint")]
             hint_code::SKIP_NEXT_INSTRUCTION => skip_next_instruction(vm),
             #[cfg(feature = "print")]

vm/src/hint_processor/builtin_hint_processor/hint_code.rs

@@ -1627,3 +1627,6 @@ ids.select_builtin = int(
   n_selected_builtins > 0 and memory[ids.selected_encodings] == memory[ids.all_encodings])
 if ids.select_builtin:
   n_selected_builtins = n_selected_builtins - 1";
+
+pub const SELECT_BUILTINS_ENTER_SCOPE: &str =
+    "vm_enter_scope({'n_selected_builtins': ids.n_selected_builtins})";