Builds on #57. Swap Value::Object's payload from Rc<BTreeMap<Value, Value>>
to Rc<Object> and migrate all call sites to the Object API.
as_object / as_object_mut keep their names but return &Object / &mut Object.
The mutable accessor handles Rc::make_mut internally, so callers no longer
do it themselves. Object grows into_value() and From<Object> for Value.
Value's serializer now delegates to Object::serialize, dropping a duplicate
non-string-key stringification path.
RVM IterationState::Object is rewritten around ObjectCursor: O(log n)
steps over a shared Rc<Object>, no eager pair snapshot. Snapshot
independence is preserved by Rc copy-on-write; setup_next_iteration
advances the cursor inline and advance() becomes a no-op for this variant.
A new iteration_state_object_is_snapshot_independent_of_source test
covers CoW against a mutated alias.
Value::Set still wraps Rc<BTreeSet<Value>>; the matching Set abstraction
and its swap ship in follow-up PRs.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Encode VM stack/context/register lifecycle invariants as
debug_assert!s. Zero cost in release; surfaces violations during
debug-mode tests and CI.
Invariants covered:
- reset_execution_state postcondition: all stacks empty, registers
resized to base and Undefined, rule_cache reset, pc/executed
counters zeroed, builtins_cache cleared, execution_state Ready.
- Per-opcode invariant check (assert_vm_invariants) invoked at the
top of run_stackless_loop and jump_to iterations: state is
Ready/Running, registers non-empty, rule_cache sized to program,
execution stack bounded by a debug-only sanity ceiling
(DEBUG_MAX_EXECUTION_STACK_DEPTH = 4096; not a production limit).
- resume() precondition: execution_state is Suspended.
- execute_suspendable_entry precondition: clean state (callers reset
immediately before).
- Rule finalize: call_rule_stack pop matches the finalized rule_index.
- IterationState::advance: Single iterator not advanced past
consumption, Array index not at usize::MAX before saturating_add.
All assertions are gated by #[cfg(debug_assertions)] (directly or via
debug_assert!) so release builds are unaffected.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
The Rego VM was designed around Rego's semantics, but Azure Policy needs
a few things Rego doesn't: host-supplied context alongside input/data,
undefined-to-null coercion for missing fields, skip-undefined collection
behavior for wildcard aliases, and non-vacuous iteration over non-array
values.
This commit adds five new instructions to bridge those gaps:
LoadContext / LoadMetadata — give programs access to host-supplied
evaluation context and cached program metadata at runtime.
ArrayPushDefined — like ArrayPush but silently drops undefined values,
so wildcard alias collection (field[*].property) excludes absent
nested properties instead of leaking undefined entries into the array.
ReturnUndefinedIfNotTrue — early return with Undefined when a guard
condition isn't satisfied, without tripping a VM assertion failure.
This models "condition doesn't match" cleanly.
CoalesceUndefinedToNull — turns Undefined into Null in-place so that
downstream builtins see null rather than short-circuiting on undefined.
The loop engine also gains an Azure Policy mode: when the source language
is "azure_policy", an Every loop over a non-array value (scalars, null,
objects) iterates once over a virtual Null element instead of being
vacuously true. This matches how field[*] behaves on non-array fields
in Azure Policy — the condition body runs once against Null, which
typically evaluates to false.
On the plumbing side: the VM gets a context field with set_context(),
metadata is cached as a Value on program load, and map_limit_error is
inlined into memory_check since it had only one call site.
Four new YAML test suites (~880 lines) cover the new instructions and
context/metadata loading, along with instruction parser, display, and
assembly listing support for everything added here.
Lints are added (deny) at crate level.
In each offending file, the failing lints are explicitly allowed.
Each file will be fixed in subsequent PRs.
Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>
* feat!: add Rego Virtual Machine (RVM) implementation
This commit introduces a register-based virtual machine for executing Rego
policies with bytecode-style instructions. Unlike the existing tree-walking
interpreter, the RVM compiles policies into instruction sequences that operate
on virtual registers, offering better performance and optimization potential.
Core Components:
Instruction Set Architecture:
- Define instruction types for data operations, control flow, and builtins
- Implement instruction parameter encoding and display formatting
- Add instruction parser with comprehensive test coverage
Virtual Machine Engine:
- Register-based execution model with program counter management
- Loop execution supporting iterators, comprehensions, and quantifiers
- Function call handling with argument evaluation and context management
- Rule evaluation with default value resolution and virtual data support
- Arithmetic and comparison operation implementations
Program Representation:
- Program listing builder with instruction sequencing
- Rule tree construction for organizing policy rules
- Binary and JSON serialization for compiled programs
- Recompilation support for program modification
Testing Infrastructure:
- Extensive YAML test suites covering all VM features
- Rust unit tests for VM execution and instruction parsing
- Test suites for loops, comprehensions, builtins, and control flow
BREAKING CHANGE: Introduces new VM execution path alongside interpreter
Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>
* docs: add detailed RVM architecture references
Introduce architecture.md explaining program artifacts, serialization, and runtime subsystems.
Document the full opcode catalog in instruction-set.md, including operands, parameter tables, and outcomes.
Walk through execution flow, stacks, and operational guidance in vm-runtime.md, tying the runtime to the new architecture docs.
Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>
---------
Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>
Anand Krishnamoorthi