Crate essential_constraint_vm

The essential constraint checking implementation.

Checking Predicates

The primary entrypoint for this crate is the check_predicate function which allows for checking a contract of constraints associated with a single predicate against some provided solution data and state slot mutations in parallel.

Checking Individual Constraints

Functions are also exposed for checking constraints individually.

• The exec_bytecode, exec_bytecode_iter and exec_ops functions allow for executing the constraint and returning the resulting Stack.
• The eval_bytecode, eval_bytecode_iter and eval_ops functions are similar to their exec_* counterparts, but expect the top of the Stack to contain a single boolean value indicating whether the constraint was satisfied (0 for false, 1 for true) and returns this value.

Performing a Single Operation

The step_op function (and related step_op_* functions) are exposed to allow for applying a single operation to the given stack. This can be useful in the case of integrating constraint operations in a downstream VM (e.g. the essential state read VM).

Understanding the Assembly

The essential-constraint-asm crate is re-exported as the asm module. See this module’s documentation for information about the expected behaviour of individual operations.

Re-exports

• pub use essential_types as types;

Modules

• asm
  Assembly for checking constraints.
• error
  The types of errors that might occur throughout constraint checking.

Structs

• Access
  All necessary solution data and state access required to check an individual predicate.
• BytecodeMapped
  A memory efficient representation of a sequence of operations parsed from bytecode.
• BytecodeMappedLazy
  A type wrapper around BytecodeMapped that lazily constructs the map from the given bytecode as operations are accessed.
• BytecodeMappedSlice
  A slice into a BytecodeMapped instance.
• Memory
  Memory for temporary storage of words.
• Repeat
  A stack of repeat counters.
• SolutionAccess
  All necessary solution data access required to check an individual predicate.
• Stack
  The VM’s Stack, i.e. a Vec of Words updated during each step of execution.
• StateSlots
  The pre and post mutation state slot values for the predicate being solved.

Enums

• ProgramControlFlow
  Update the program to a new position or halt it.

Traits

• OpAccess
  Types that provide access to operations.

Functions

• check_predicate
  Check whether the constraints of a single predicate are met for the given solution data and state slot mutations. All constraints are checked in parallel.
• eval
  Evaluate the operations of a single constraint and return its boolean result.
• eval_bytecode
  Evaluate the bytecode of a single constraint and return its boolean result.
• eval_bytecode_iter
  Evaluate the bytecode of a single constraint and return its boolean result.
• eval_ops
  Evaluate the operations of a single constraint and return its boolean result.
• exec
  Execute the operations of a constraint and return the resulting stack.
• exec_bytecode
  Execute the bytecode of a constraint and return the resulting stack.
• exec_bytecode_iter
  Execute the bytecode of a constraint and return the resulting stack.
• exec_ops
  Execute the operations of a constraint and return the resulting stack.
• mut_keys
  A helper for collecting all mutable keys that are proposed for mutation for the predicate at the given index.
• mut_keys_set
  Get the contract of mutable keys for this predicate.
• mut_keys_slices
  Get the mutable keys as slices
• step_on_temporary
  Step forward constraint checking by the given temporary operation.
• step_on_total_control_flow
  Step forward constraint checking by the given total control flow operation.
• step_op
  Step forward constraint checking by the given operation.
• step_op_access
  Step forward constraint checking by the given access operation.
• step_op_alu
  Step forward constraint checking by the given ALU operation.
• step_op_crypto
  Step forward constraint checking by the given crypto operation.
• step_op_pred
  Step forward constraint checking by the given predicate operation.
• step_op_stack
  Step forward constraint checking by the given stack operation.
• transient_data
  Create a transient data map from the solution.

Type Aliases

• CheckResult
  Shorthand for a Result where the error type is a CheckError.
• ConstraintResult
  Shorthand for a Result where the error type is a ConstraintError.
• OpResult
  Shorthand for a Result where the error type is an OpError.
• StackResult
  Shorthand for a Result where the error type is a StackError.
• StateSlotSlice
  The state slots declared within the predicate.
• TransientData
  Transient data map.