Move NewContext function to engine package

Call order is now enforced when using the root `php` package by moving
the `NewContext` function in the `engine` package, as a method of the
`Engine` method receiver. Further clean-ups have been made to the code
as a result of this change.

context/context.c

@@ -92,6 +92,10 @@ void context_bind(engine_context *context, char *name, void *zvalptr) {
 	return NULL;
 }
 
+int context_write(engine_context *context, const char *str, unsigned int len) {
+	return contextWrite(context->parent, (void *) str, len);
+}
+
 void context_destroy(engine_context *context) {
 	php_request_shutdown((void *) 0);
 

context/context.go

@@ -81,15 +81,17 @@ func (c *Context) Eval(script string) error {
 	return nil
 }
 
-// Destroy tears down the current execution context along with any values binded
-// in.
+// Destroy tears down the current execution context along with any active value
+// bindings for that context.
 func (c *Context) Destroy() {
 	for _, v := range c.values {
 		v.Destroy()
 	}
 
-	C.context_destroy(c.context)
-	c = nil
+	if c.context != nil {
+		C.context_destroy(c.context)
+		c.context = nil
+	}
 }
 
 // New creates a new execution context, passing all script output into w. It
@@ -107,8 +109,8 @@ func New(w io.Writer) (*Context, error) {
 	return ctx, nil
 }
 
-//export context_write
-func context_write(ctxptr unsafe.Pointer, buffer unsafe.Pointer, length C.uint) C.int {
+//export contextWrite
+func contextWrite(ctxptr unsafe.Pointer, buffer unsafe.Pointer, length C.uint) C.int {
 	c := (*Context)(ctxptr)
 
 	written, err := c.writer.Write(C.GoBytes(buffer, C.int(length)))

context/context.h

@@ -11,13 +11,14 @@ typedef struct _engine_context {
 	#endif
 
 	void *parent; // Pointer to parent Go context, used for passing to callbacks.
-	int (*write)(void *parent, void *msg, unsigned int len);
+	int (*write)(struct _engine_context *context, const char *msg, unsigned int len);
 } engine_context;
 
 engine_context *context_new(void *parent);
 void context_exec(engine_context *context, char *filename);
 void context_eval(engine_context *context, char *script);
 void context_bind(engine_context *context, char *name, void *zvalptr);
+int context_write(engine_context *context, const char *str, unsigned int len);
 void context_destroy(engine_context *context);
 
 #endif

engine/engine.c

@@ -23,10 +23,10 @@ const char engine_ini_defaults[] =
 	"max_input_time = -1\n\0"
 ;
 
-static int engine_ub_write(const char *str, uint str_length TSRMLS_DC)  {
+static int engine_ub_write(const char *str, uint str_length TSRMLS_DC) {
 	engine_context *context = (engine_context *) SG(server_context);
 
-	int written = context->write(context->parent, (void *) str, str_length);
+	int written = context->write(context, str, str_length);
 	if (written != str_length) {
 		php_handle_aborted_connection();
 	}

engine/engine.go

@@ -16,18 +16,41 @@ import "C"
 
 import (
 	"fmt"
+	"io"
+
+	"github.com/deuill/go-php/context"
 )
 
 // Engine represents the core PHP engine bindings.
 type Engine struct {
-	engine *C.struct__php_engine
+	engine   *C.struct__php_engine
+	contexts []*context.Context
 }
 
-// Destroy shuts down and frees any resources related to the PHP engine
-// bindings.
+// NewContext creates a new execution context on which scripts can be executed
+// and variables can be binded. It corresponds to PHP's RINIT (request init)
+// phase.
+func (e *Engine) NewContext(w io.Writer) (*context.Context, error) {
+	c, err := context.New(w)
+	if err != nil {
+		return nil, err
+	}
+
+	e.contexts = append(e.contexts, c)
+
+	return c, nil
+}
+
+// Destroy shuts down and frees any resources related to the PHP engine bindings.
 func (e *Engine) Destroy() {
-	C.engine_shutdown(e.engine)
-	e = nil
+	for _, c := range e.contexts {
+		c.Destroy()
+	}
+
+	if e.engine != nil {
+		C.engine_shutdown(e.engine)
+		e.engine = nil
+	}
 }
 
 // New initializes a PHP engine instance on which contexts can be executed. It
@@ -38,5 +61,5 @@ func New() (*Engine, error) {
 		return nil, fmt.Errorf("PHP engine failed to initialize")
 	}
 
-	return &Engine{engine: ptr}, nil
+	return &Engine{engine: ptr, contexts: make([]*context.Context, 0)}, nil
 }

php.go

@@ -8,9 +8,6 @@
 package php
 
 import (
-	"io"
-
-	"github.com/deuill/go-php/context"
 	"github.com/deuill/go-php/engine"
 )
 
@@ -19,10 +16,3 @@ import (
 func New() (*engine.Engine, error) {
 	return engine.New()
 }
-
-// NewContext creates a new execution context on which scripts can be executed
-// and variables can be binded. It corresponds to PHP's RINIT (request init
-// phase and *must* be preceeded by a call to `php.New()`.
-func NewContext(w io.Writer) (*context.Context, error) {
-	return context.New(w)
-}

php_test.go

@@ -49,12 +49,10 @@ func TestNewEngineContext(t *testing.T) {
 
 	defer e.Destroy()
 
-	ctx, err := NewContext(os.Stdout)
+	_, err = e.NewContext(os.Stdout)
 	if err != nil {
 		t.Errorf("NewContext(): %s", err)
 	}
-
-	defer ctx.Destroy()
 }
 
 var execTests = []struct {
@@ -68,10 +66,9 @@ func TestContextExec(t *testing.T) {
 	var w MockWriter
 
 	e, _ := New()
-	ctx, _ := NewContext(&w)
+	ctx, _ := e.NewContext(&w)
 
 	defer e.Destroy()
-	defer ctx.Destroy()
 
 	for _, tt := range execTests {
 		file := path.Join(testDir, tt.file)
@@ -94,16 +91,16 @@ var evalTests = []struct {
 }{
 	{"echo 'Hello World';", "Hello World"},
 	{"$i = 10; $d = 20; echo $i + $d;", "30"},
+	{"notascript{}!!*", ""},
 }
 
 func TestContextEval(t *testing.T) {
 	var w MockWriter
 
 	e, _ := New()
-	ctx, _ := NewContext(&w)
+	ctx, _ := e.NewContext(&w)
 
 	defer e.Destroy()
-	defer ctx.Destroy()
 
 	for _, tt := range evalTests {
 		if err := ctx.Eval(tt.script); err != nil {
@@ -135,10 +132,9 @@ func TestContextBind(t *testing.T) {
 	var w MockWriter
 
 	e, _ := New()
-	ctx, _ := NewContext(&w)
+	ctx, _ := e.NewContext(&w)
 
 	defer e.Destroy()
-	defer ctx.Destroy()
 
 	for i, tt := range bindTests {
 		if err := ctx.Bind(strconv.FormatInt(int64(i), 10), tt.value); err != nil {

value/value.go

@@ -36,20 +36,22 @@ func (v *Value) Ptr() unsafe.Pointer {
 // Destroy removes all active references to the internal PHP value and frees
 // any resources used.
 func (v *Value) Destroy() {
-	C.value_destroy(v.value)
-	v = nil
+	if v.value != nil {
+		C.value_destroy(v.value)
+		v.value = nil
+	}
 }
 
 // New creates a PHP value representtion of a Go value val. Available bindings
 // for Go to PHP types are:
 //
-//	int -> integer
-//	float64 -> double
-//	bool -> boolean
-//	string -> string
-//	slice -> indexed array
+//	int             -> integer
+//	float64         -> double
+//	bool            -> boolean
+//	string          -> string
+//	slice           -> indexed array
 //	map[int|string] -> associative array
-//	struct -> object
+//	struct          -> object
 //
 // Bindings for functions and method receivers to PHP functions and classes are
 // only available in the engine scope, and must be predeclared before context