init

src/device.c

@@ -0,0 +1,28 @@
+#include "device.h"
+#include <string.h>
+
+static void pressPwrMethod(Device_t *device) {
+    device->state.methods.pressPwr(device);
+}
+
+static void pressStrInputMethod(Device_t *device) {
+    device->state.methods.pressStrInput(device);
+}
+
+static void pressLockMethod(Device_t *device) {
+    device->state.methods.pressLock(device);
+}
+
+void initDevice(Device_t* device) {
+    *device = (Device_t){
+        .state = NULL,
+        .entered_string = "frogs",
+        .entered_string_len = 6,
+        .methods = (DeviceInterface_t){
+            .pressPwr = &pressPwrMethod, 
+            .pressStrInput = &pressStrInputMethod, 
+            .pressLock = &pressLockMethod, 
+        },
+    };
+}
+

src/device.h

@@ -0,0 +1,57 @@
+#pragma once
+// lets assume we have some app with 4 states, 3 differnet input that change the state
+// states : [locked, unlocked, off, debug] 
+// change actions : lock, str_input, power button
+//
+//      pwr     ┌──────────┐    pwr    
+// ┌─────┴┬────►│off state │◄────┴┐    
+// │      │     └────┬─────┘      │    
+// │      │          │            │    
+// │      │    ┌─────┘            │    
+// │      │    ├ pwr              │    
+// │      │    ▼                  │    
+// │   ┌──┴─────┐  str=pwd   ┌────┴───┐
+// │   │lock    ├─────┴─────►│unlock  │
+// │   │state   │            │state   │
+// │   └──────┬─┘◄───┬───────┴──┬─────┘
+// │     ^    │     lck         │      
+// │ lck ┤    ├ str=dbg         ├ str=dbg      
+// │     │    │                 │      
+// │     │    │                 │      
+// │     │    ▼                 │      
+// │   ┌─┴──────┐               │      
+// └───┤debug   │◄──────────────┘      
+//     │        │                      
+//     └────────┘                      
+
+typedef struct Device_s Device_t;
+
+
+typedef struct DeviceInterface_s{
+    // all the actions that change the state
+    // normally there wouldnt be any args
+    // but as we dont have a protected keyword
+    // we have to pass in the device to change 
+    // the state
+    void (*pressPwr)(Device_t*);
+    void (*pressStrInput)(Device_t*);
+    void (*pressLock)(Device_t*);
+}DeviceInterface_t;
+
+typedef struct DeviceState_s{
+    const char* state_name;
+    Device_t* device;
+    DeviceInterface_t methods;
+}DeviceState_t;
+
+struct Device_s{
+    // in theroy this is also the flyweight pattern
+    DeviceState_t state;
+    char* entered_string;
+    int entered_string_len;
+
+    DeviceInterface_t methods;
+};
+
+
+void initDevice(Device_t* device);

src/main.c

@@ -0,0 +1,22 @@
+#include "states/state.h"
+#include "device.h"
+
+int main() {
+    Device_t device;
+    initDevice(&device);
+    // sets the device to off on start up
+    setOffState(&device);
+
+    // turn on the device
+    device.methods.pressPwr(&device);
+
+    // send the current string
+    device.methods.pressStrInput(&device);
+    
+    // send in the right string
+    device.entered_string = "pwd";
+    device.methods.pressStrInput(&device);
+
+    return 0;
+}
+

src/states/debug_state.c

@@ -0,0 +1,33 @@
+#include <stdio.h>
+
+#include "state.h"
+#include "../device.h"
+
+const char debug_state_name[] = __FILE_NAME__;
+
+static void pressPwrMethod(Device_t *device) {
+    printf("turning off device\n");
+    setOffState(device);
+}
+
+static void pressStrInputMethod(Device_t *device) {
+    printf("nothing happens\n");
+}
+
+static void pressLockMethod(Device_t *device) {
+    printf("locking device\n");
+    setOffState(device);
+}
+
+void setDebugState(Device_t *device) {
+    device->state = (DeviceState_t){
+        .state_name = debug_state_name,
+        .device = device,
+        .methods = (DeviceInterface_t){
+            .pressPwr = &pressPwrMethod,
+            .pressStrInput = &pressStrInputMethod,
+            .pressLock = &pressLockMethod,
+        },
+    };
+}
+

src/states/lock_state.c

@@ -0,0 +1,45 @@
+#include <stdio.h>
+#include <string.h>
+
+#include "state.h"
+#include "../device.h"
+
+const char lock_state_name[] = __FILE_NAME__;
+
+static void pressPwrMethod(Device_t *device) {
+    printf("turning off device\n");
+    setOffState(device);
+}
+
+static void pressStrInputMethod(Device_t *device) {
+    if (strcmp(device->entered_string, "dbg") == 0) {
+        printf("entering debug state\n");
+        setDebugState(device);
+        return;
+    }
+    if (strcmp(device->entered_string, "pwd") == 0) {
+        printf("entering unlock state\n");
+        setUnlockState(device);
+        return;
+    }
+
+    printf("unknown string %s\n", device->entered_string);
+
+}
+
+static void pressLockMethod(Device_t *device) {
+    printf("nothing happens\n");
+}
+
+void setLockState(Device_t *device) {
+    device->state = (DeviceState_t){
+        .state_name = lock_state_name,
+        .device = device,
+        .methods = (DeviceInterface_t){
+            .pressPwr = &pressPwrMethod,
+            .pressStrInput = &pressStrInputMethod,
+            .pressLock = &pressLockMethod,
+        },
+    };
+}
+

src/states/off_state.c

@@ -0,0 +1,31 @@
+#include "state.h"
+#include "../device.h"
+#include <stdio.h>
+
+const char off_state_name[] = __FILE_NAME__;
+
+static void pressPwrMethod(Device_t *device) {
+    printf("turning on device\n");
+    setLockState(device);
+}
+
+static void pressStrInputMethod(Device_t *device) {
+    printf("nothing happens\n");
+}
+
+static void pressLockMethod(Device_t *device) {
+    printf("nothing happens\n");
+}
+
+void setOffState(Device_t *device) {
+    device->state = (DeviceState_t){
+        .state_name = off_state_name,
+        .device = device,
+        .methods = (DeviceInterface_t){
+            .pressPwr = &pressPwrMethod,
+            .pressStrInput = &pressStrInputMethod,
+            .pressLock = &pressLockMethod,
+        },
+    };
+}
+

src/states/state.h

@@ -0,0 +1,7 @@
+#pragma once
+#include "../device.h"
+
+void setLockState(Device_t *device);
+void setUnlockState(Device_t *device);
+void setDebugState(Device_t *device);
+void setOffState(Device_t *device);

src/states/unlock_state.c

@@ -0,0 +1,37 @@
+#include "state.h"
+#include "../device.h"
+#include <stdio.h>
+#include <string.h>
+
+const char name[] = __FILE_NAME__;
+
+static void pressPwrMethod(Device_t *device) {
+    printf("turning off device\n");
+    setOffState(device);     
+}
+
+static void pressStrInputMethod(Device_t *device) {
+    if (strcmp(device->entered_string, "dbg") == 0) {
+        printf("entering debug state\n");
+        setDebugState(device);
+    }
+    printf("unknown string %s\n", device->entered_string);
+}
+
+static void pressLockMethod(Device_t *device) {
+    printf("locking device\n");
+    setLockState(device);
+}
+
+void setUnlockState(Device_t *device) {
+    device->state = (DeviceState_t){
+        .state_name = name,
+        .device = device,
+        .methods = (DeviceInterface_t){
+            .pressPwr = &pressPwrMethod,
+            .pressStrInput = &pressStrInputMethod,
+            .pressLock = &pressLockMethod,
+        },
+    };
+}
+