Pure C command pattern

command_pattern.c

#include "command_pattern.h"

/** private **/

static int executorRun(ExecutorPtr executor)
{
	return executor->command->run(executor->command, executor->invoker);
}

static Executor executionContextInit(InvokerPtr invoker, CommandPtr command)
{
	Executor excecutor = EXECUTOR_INVALID;
	if (invoker && command)
	{
		executor.run = ExecutorRun;
		executor.invoker = invoker;
		executor.command = command;
	}
	return excecutor;
}

/** public **/

/* invoker */

Executor invokerCallExecutionContextInit(InvokerPtr invoker, CommandPtr command)
{
	return (invoker && commandIsValid(command))
			? invoker->executionContextInit(invoker, command)
			: EXECUTOR_INVALID
}

/* command */

Command commandCreateDefault(CallbackCommandRun commandRun)
{
	Command command = COMMAND_INVALID;
	if (commandRun)
	{
		command.run = commandRun;
	}
	return command;
}

int commandIsValid(CommandPtr command)
{
	return command && command->run;
}

/* executor */

int executorIsValid(ExecutorPtr executor)
{
	return executor
			&& excecutor->run != EXECUTOR_INVALID.run
			&& excecutor->invoker != EXECUTOR_INVALID.invoker
			&& excecutor->command != EXECUTOR_INVALID.command;
}

/* global */

const Executor EXECUTOR_INVALID = { 0, 0, 0 };
const Command COMMAND_INVALID = { 0 };
const Invoker INVOKER_DEFAULT = { executionContextInit };

command_pattern.h

#ifndef PURE_C_COMMAND_PATTERN
#define PURE_C_COMMAND_PATTERN

struct Invoker;
typedef struct Invoker Invoker;
typedef Invoker* InvokerPtr;

struct Command;
typedef struct Command Command;
typedef Command* CommandPtr;

struct Executor;
typedef struct Executor Executor;
typedef Executor* ExecutorPtr;

typedef Executor(*CallbackExecutionContextInit)(InvokerPtr, CommandPtr);
typedef int(*CallbackCommandRun)(CommandPtr, InvokerPtr);
typedef int(*CallbackExecutorRun)(ExecutorPtr);

/* invoker */

struct Invoker
{
	CallbackExecutionContextInit executionContextInit;
};
Executor invokerCallExecutionContextInit(InvokerPtr invoker, CommandPtr command);

/* command */

struct Command
{
	CallbackCommandRun run;
};
Command commandCreateDefault(CallbackCommandRun commandRun);
int commandIsValid(CommandPtr command);

/* executor */

struct Executor
{
	CallbackExecutorRun run;
	InvokerPtr invoker;
	CommandPtr command;
};
int executorIsValid(ExecutorPtr executor);

/* global */

extern const Invoker INVOKER_DEFAULT;
extern const Command COMMAND_INVALID;
extern const Executor EXECUTOR_INVALID;

#endif /* PURE_C_COMMAND_PATTERN */