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Module StackState

module StackState: sig .. end
Definition and utility functions for stack state manipulation.

Types

type locals
The type of locals: integer-index type information. Elements are of Attribute.verification_type_info type.
type stack
The type of operand stacks. Elements are of Attribute.verification_type_info type.
type t = {
   locals :locals; (*type information for the locals.*)
   stack :stack; (*type information for the operand stack.*)
}
The type of stack states.

Exception

type error =
| Unsupported_instruction of string
| Empty_stack
| Invalid_local_index of Utils.u2 * int
| Invalid_stack_top of Attribute.verification_type_info * Attribute.verification_type_info
| Invalid_local_contents of Utils.u2 * Attribute.verification_type_info
* Attribute.verification_type_info
| Invalid_local_contents_placeholder of Utils.u2 * Attribute.verification_type_info
| Reference_waited of Attribute.verification_type_info
| Reference_waited_placeholder_found
| Array_waited
| Category1_waited
| Category2_waited
| Different_stack_sizes of int * int
| Invalid_primitive_array_type
| Empty_frame_list
| Different_frames of Utils.u2 
exception Exception of error
val string_of_error : error -> string

Construction

val make_empty : unit -> t
Returns an empty state (no local, and no operand on stack).
val make_of_parameters : (Name.for_class * bool) option ->
       Descriptor.for_parameter list -> t
make_of_parameters cn p returns the state describing the stack at the beginning of a method. cn is the enclosing class for the method if it is an instance method (the boolean indicating whether the method is a constructor), None being used for static methods. p is the list of parameters of the method.
val make_of_method : Name.for_class -> Method.t -> t
make_of_method cn m returns the state describing the stack at the beginning for the method m in the class cn.

Access and modification

val locals_size : t -> int
Returns the size of the locals for the passed state.
val stack_size : t -> int
Returns the size of the operand stack for the passed state.
val equal : t -> t -> bool
Equality over stack states.
val push : Attribute.verification_type_info -> stack -> stack
push v s returns a stack similar to s with v pushed on its top.
val top : stack -> Attribute.verification_type_info
top s returns the top element of s. Raises Exception if s is empty.
val pop : stack -> stack
pop s returns s without its top element. Raises Exception if s is empty.
val pop_if : Attribute.verification_type_info -> stack -> stack
pop_if v s returns s without its top element if this element is equal to v, raising Exception otherwise. Raises Exception if s is empty.
val pop_if_category1 : stack -> Attribute.verification_type_info * stack
pop_if_category1 s returns a couple with the top element, and s without its top element. Raises Exception if s is empty, or if its top element is not a category 1 element.
val empty : unit -> stack
Returns an empty stack.
val only_exception : Name.for_class -> stack
Returns a stack containing only the passed element.

Operations

val update : Name.for_class -> Utils.u2 -> Instruction.t -> t -> t
update cn ofs i st returns the state st updated according to the instruction i located at offset ofs (in class cn). Raises Exception if the passed state is not compatible with the instruction, or if the instruction is unsupported (jsr, jsr_w, ret, or wide ret).
type 'a unifier = 'a -> 'a -> 'a
The type of unifiers, that is functions that return an element that generalizes the passed ones.
type instance = [ `Array_type of Descriptor.array_type
       | `Class_or_interface of Name.for_class ]
Type abbreviation, used to represent any Java instance.
val make_array_unifier : Name.for_class unifier ->
       Descriptor.array_type -> Descriptor.array_type -> instance
Builds an array unifier from a class unifier that is used to unify array elements.
val make_unifier : Name.for_class unifier -> instance unifier
Builds a unifier from a class unifier.
val unify_to_java_lang_Object : instance unifier
A unifier that returns java.lang.Object when passed classes are different.
val unify_to_closest_common_parent : ClassLoader.t ->
       (Name.for_class * Name.for_class option) list ->
       instance unifier
A unifier that returns the closest common parent of the passed classes. The class loader is used to load the parents of the passed classes. The passed list is a (class, parent) association list overriding the class loader.
val unify_to_parent_list : (Name.for_class * Name.for_class option) list ->
       instance unifier
A unifier that returns the closest common parent of the passed classes, using the passed list as a (class, parent) association list.
val unify : instance unifier ->
       t -> t -> t
unify u st1 st2 returns a state that generalizes st1 and st2.
val encode : ?optimize:bool ->
       (Utils.u2 * t) list -> Attribute.stack_map_frame list
Encodes the passed list of (offset, state) couples into attribute values. Raises Exception if the passed list is empty, or contains different frames at the same offset.