Bind new support for tables

Binds functions added in
bytecodealliance/wasmtime#1654

Closes #5

Author: alexcrichton

table.go

@@ -1,15 +1,38 @@
 package wasmtime
 
-// #include <wasm.h>
+// #include <wasmtime.h>
 import "C"
-import "runtime"
+import (
+	"errors"
+	"runtime"
+)
 
 type Table struct {
 	_ptr     *C.wasm_table_t
 	_owner   interface{}
 	freelist *freeList
 }
 
+// Creates a new `Table` in the given `Store` with the specified `ty`.
+//
+// The `ty` must be a `funcref` table and `init` is the initial value for all
+// table slots, and is allowed to be `nil`.
+func NewTable(store *Store, ty *TableType, init *Func) (*Table, error) {
+	var init_ptr *C.wasm_func_t
+	if init != nil {
+		init_ptr = init.ptr()
+	}
+	var ptr *C.wasm_table_t
+	err := C.wasmtime_funcref_table_new(store.ptr(), ty.ptr(), init_ptr, &ptr)
+	runtime.KeepAlive(store)
+	runtime.KeepAlive(ty)
+	runtime.KeepAlive(init)
+	if err != nil {
+		return nil, mkError(err)
+	}
+	return mkTable(ptr, store.freelist, nil), nil
+}
+
 func mkTable(ptr *C.wasm_table_t, freelist *freeList, owner interface{}) *Table {
 	f := &Table{_ptr: ptr, _owner: owner, freelist: freelist}
 	if owner == nil {
@@ -35,12 +58,74 @@ func (t *Table) owner() interface{} {
 	return t
 }
 
+// Returns the size of this table in units of elements.
 func (t *Table) Size() uint32 {
 	ret := C.wasm_table_size(t.ptr())
 	runtime.KeepAlive(t)
 	return uint32(ret)
 }
 
+// Grows this funcref table by the number of units specified, using the
+// specified initializer value for new slots.
+//
+// Note that `init` is allowed to be `nil`.
+//
+// Returns an error if the table failed to grow, or the previous size of the
+// table if growth was successful.
+func (t *Table) Grow(delta uint32, init *Func) (uint32, error) {
+	var init_ptr *C.wasm_func_t
+	if init != nil {
+		init_ptr = init.ptr()
+	}
+	var prev C.uint32_t
+	err := C.wasmtime_funcref_table_grow(t.ptr(), C.uint32_t(delta), init_ptr, &prev)
+	runtime.KeepAlive(t)
+	runtime.KeepAlive(init)
+	if err == nil {
+		return uint32(prev), nil
+	} else {
+		return 0, mkError(err)
+	}
+}
+
+// Gets an item from this table from the specified index.
+//
+// Returns an error if the index is out of bounds, or returns a function (which
+// may be `nil`) if the index is in bounds corresponding to the entry at the
+// specified index.
+func (t *Table) Get(idx uint32) (*Func, error) {
+	var func_ptr *C.wasm_func_t
+	ok := C.wasmtime_funcref_table_get(t.ptr(), C.uint32_t(idx), &func_ptr)
+	runtime.KeepAlive(t)
+	if ok {
+		if func_ptr == nil {
+			return nil, nil
+		}
+		return mkFunc(func_ptr, t.freelist, nil), nil
+	} else {
+		return nil, errors.New("index out of bounds")
+	}
+}
+
+// Sets an item in this table at the specified index.
+//
+// Returns an error if the index is out of bounds.
+func (t *Table) Set(idx uint32, val *Func) error {
+	var func_ptr *C.wasm_func_t
+	if val != nil {
+		func_ptr = val.ptr()
+	}
+	err := C.wasmtime_funcref_table_set(t.ptr(), C.uint32_t(idx), func_ptr)
+	runtime.KeepAlive(t)
+	runtime.KeepAlive(val)
+	if err == nil {
+		return nil
+	} else {
+		return mkError(err)
+	}
+}
+
+// Returns the underlying type of this table
 func (t *Table) Type() *TableType {
 	ptr := C.wasm_table_type(t.ptr())
 	runtime.KeepAlive(t)

table_test.go

@@ -0,0 +1,88 @@
+package wasmtime
+
+import "testing"
+
+func TestTable(t *testing.T) {
+	store := NewStore(NewEngine())
+	ty := NewTableType(NewValType(KindFuncref), Limits{Min: 1, Max: 3})
+	table, err := NewTable(store, ty, nil)
+	if err != nil {
+		panic(err)
+	}
+	if table.Size() != 1 {
+		panic("wrong size")
+	}
+
+	f, err := table.Get(0)
+	if err != nil {
+		panic(err)
+	}
+	if f != nil {
+		panic("expected nil")
+	}
+	f, err = table.Get(1)
+	if err == nil {
+		panic("expected error")
+	}
+	if f != nil {
+		panic("expected nil")
+	}
+
+	err = table.Set(0, nil)
+	if err != nil {
+		panic(err)
+	}
+	err = table.Set(1, nil)
+	if err == nil {
+		panic("expected error")
+	}
+	err = table.Set(0, WrapFunc(store, func() {}))
+	if err != nil {
+		panic(nil)
+	}
+	f, err = table.Get(0)
+	if err != nil {
+		panic(err)
+	}
+	if f == nil {
+		panic("expected not nil")
+	}
+
+	prev_size, err := table.Grow(1, nil)
+	if err != nil {
+		panic(err)
+	}
+	if prev_size != 1 {
+		print(prev_size)
+		panic("bad prev")
+	}
+	f, err = table.Get(1)
+	if err != nil {
+		panic(err)
+	}
+	if f != nil {
+		panic("expected nil")
+	}
+
+	called := false
+	_, err = table.Grow(1, WrapFunc(store, func() {
+		called = true
+	}))
+	if err != nil {
+		panic(err)
+	}
+	f, err = table.Get(2)
+	if err != nil {
+		panic(err)
+	}
+	if called {
+		panic("called already?")
+	}
+	_, err = f.Call()
+	if err != nil {
+		panic(err)
+	}
+	if !called {
+		panic("should have called")
+	}
+}