libwren-sys 0.1.0

FFI bindings for the wren embedded programming language
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130

#include <stdio.h>
#include <string.h>

#include "foreign_class.h"

static int finalized = 0;

static void apiFinalized(WrenVM* vm)
{
  wrenSetSlotDouble(vm, 0, finalized);
}

static void counterAllocate(WrenVM* vm)
{
  double* value = (double*)wrenSetSlotNewForeign(vm, 0, 0, sizeof(double));
  *value = 0;
}

static void counterIncrement(WrenVM* vm)
{
  double* value = (double*)wrenGetSlotForeign(vm, 0);
  double increment = wrenGetSlotDouble(vm, 1);

  *value += increment;
}

static void counterValue(WrenVM* vm)
{
  double value = *(double*)wrenGetSlotForeign(vm, 0);
  wrenSetSlotDouble(vm, 0, value);
}

static void pointAllocate(WrenVM* vm)
{
  double* coordinates = (double*)wrenSetSlotNewForeign(vm, 0, 0, sizeof(double[3]));

  // This gets called by both constructors, so sniff the slot count to see
  // which one was invoked.
  if (wrenGetSlotCount(vm) == 1)
  {
    coordinates[0] = 0.0;
    coordinates[1] = 0.0;
    coordinates[2] = 0.0;
  }
  else
  {
    coordinates[0] = wrenGetSlotDouble(vm, 1);
    coordinates[1] = wrenGetSlotDouble(vm, 2);
    coordinates[2] = wrenGetSlotDouble(vm, 3);
  }
}

static void pointTranslate(WrenVM* vm)
{
  double* coordinates = (double*)wrenGetSlotForeign(vm, 0);
  coordinates[0] += wrenGetSlotDouble(vm, 1);
  coordinates[1] += wrenGetSlotDouble(vm, 2);
  coordinates[2] += wrenGetSlotDouble(vm, 3);
}

static void pointToString(WrenVM* vm)
{
  double* coordinates = (double*)wrenGetSlotForeign(vm, 0);
  char result[100];
  sprintf(result, "(%g, %g, %g)",
      coordinates[0], coordinates[1], coordinates[2]);
  wrenSetSlotString(vm, 0, result);
}

static void resourceAllocate(WrenVM* vm)
{
  int* value = (int*)wrenSetSlotNewForeign(vm, 0, 0, sizeof(int));
  *value = 123;
}

static void resourceFinalize(void* data)
{
  // Make sure we get the right data back.
  int* value = (int*)data;
  if (*value != 123) exit(1);

  finalized++;
}

static void badClassAllocate(WrenVM* vm)
{
  wrenEnsureSlots(vm, 1);
  wrenSetSlotString(vm, 0, "Something went wrong");
  wrenAbortFiber(vm, 0);
}

WrenForeignMethodFn foreignClassBindMethod(const char* signature)
{
  if (strcmp(signature, "static ForeignClass.finalized") == 0) return apiFinalized;
  if (strcmp(signature, "Counter.increment(_)") == 0) return counterIncrement;
  if (strcmp(signature, "Counter.value") == 0) return counterValue;
  if (strcmp(signature, "Point.translate(_,_,_)") == 0) return pointTranslate;
  if (strcmp(signature, "Point.toString") == 0) return pointToString;

  return NULL;
}

void foreignClassBindClass(
    const char* className, WrenForeignClassMethods* methods)
{
  if (strcmp(className, "Counter") == 0)
  {
    methods->allocate = counterAllocate;
    return;
  }

  if (strcmp(className, "Point") == 0)
  {
    methods->allocate = pointAllocate;
    return;
  }

  if (strcmp(className, "Resource") == 0)
  {
    methods->allocate = resourceAllocate;
    methods->finalize = resourceFinalize;
    return;
  }

  if (strcmp(className, "BadClass") == 0)
  {
    methods->allocate = badClassAllocate;
    return;
  }
}