callctx

Documentation

Overview

Package callctx defines a function call Context for static analysis.

A context is a map between local variables of a function and their instances. An element in the context is abstracted as a key-value store using the Key type and the Value type. The primary use for a context is to propagate local variables to other scopes through different forms of function calls using a substitution operation called Switch. A context Switch transforms context from the perspective of a caller to that of a callee.

This package is inspired by the builtin context package but for context-sensitive variable propagation.

Index

• func Deref(ctx Context, ptr, val store.Key) (store.Value, error)
• type Callee
• type Context
  • func Switch(parent Context, call *funcs.Instance) Context
  • func Toplevel() Context
• type Updater

Functions

func Deref

func Deref(ctx Context, ptr, val store.Key) (store.Value, error)

Types

type Callee

type Callee interface {
	CallerCtx() Context
	Call() *funcs.Instance
}

A Callee is a context created by a call, Call() returns the call instance.

type Context

type Context interface {
	Get(store.Key) store.Value
	Put(store.Key, store.Value)
	// contains filtered or unexported methods
}

A Context is map between local variables and their instances. Get and Put are the main functions to access the contents of the map.

func Switch

func Switch(parent Context, call *funcs.Instance) Context

Switch performs a context switch from parent (caller) to a new callee context. The switch matches up caller arguments in parent in the call ↔ translated in the callee as call parameters.

func Toplevel

func Toplevel() Context

Toplevel returns an empty context.

It is used for representing a top-level context at entry points of analysis.

type Updater

type Updater interface {
	PutObj(k store.Key, v ssa.Value)                 // Add Value.
	PutUniq(k store.Key, v store.ValueWrapper) error // Add pre-initialised Value.
}

Updater is an interface for a context that has the ability to modify the underlying storage which the instances point to.