Merge pull request #114 from pfalcon/streams-bootstrap

Define buffer and stream protocols, and other starting bits of io.* framework, with io.FileIO-like implementation for Unix

4 files changed, 99 insertions, 0 deletions

diff --git a/py/obj.h b/py/obj.h
index f8bc790121..a3af7f556b 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -84,6 +84,41 @@ typedef struct _mp_method_t {
     mp_const_obj_t fun;
 } mp_method_t;
 
+// Buffer protocol
+typedef struct _buffer_info_t {
+    // if we'd bother to support various versions of structure
+    // (with different number of fields), we can distinguish
+    // them with ver = sizeof(struct). Cons: overkill for *micro*?
+    //int ver; // ?
+
+    void *buf;
+    machine_int_t len;
+
+    // Rationale: have array.array and have SIMD operations on them
+    // Cons: users can pass item size to processing functions themselves,
+    // though that's not "plug&play"
+    // int itemsize;
+
+    // Rationale: to load arbitrary-sized sprites directly to LCD
+    // Cons: a bit adhoc usecase
+    // int stride;
+} buffer_info_t;
+#define BUFFER_READ  (1)
+#define BUFFER_WRITE (2)
+#define BUFFER_RW (BUFFER_READ | BUFFER_WRITE)
+typedef struct _mp_buffer_p_t {
+    machine_int_t (*get_buffer)(mp_obj_t obj, buffer_info_t *bufinfo, int flags);
+} mp_buffer_p_t;
+
+// Stream protocol
+typedef struct _mp_stream_p_t {
+    // On error, functions should return -1 and fill in *errcode (values are
+    // implementation-dependent, but will be exposed to user, e.g. via exception).
+    machine_int_t (*read)(mp_obj_t obj, void *buf, machine_uint_t size, int *errcode);
+    machine_int_t (*write)(mp_obj_t obj, const void *buf, machine_uint_t size, int *errcode);
+    // add seek() ?
+} mp_stream_p_t;
+
 struct _mp_obj_type_t {
     mp_obj_base_t base;
     const char *name;
@@ -98,6 +133,12 @@ struct _mp_obj_type_t {
     mp_fun_1_t getiter;
     mp_fun_1_t iternext;
 
+    // Alternatively, pointer(s) to interfaces to save space
+    // in mp_obj_type_t at the expense of extra pointer and extra dereference
+    // when actually used.
+    mp_buffer_p_t buffer_p;
+    mp_stream_p_t stream_p;
+
     const mp_method_t *methods;
 
     /*
diff --git a/py/py.mk b/py/py.mk
index 0502dc0ffd..be32bc5fb3 100644
--- a/py/py.mk
+++ b/py/py.mk
@@ -68,6 +68,7 @@ PY_O_BASENAME = \
 	objstr.o \
 	objtuple.o \
 	objtype.o \
+	stream.o \
 	builtin.o \
 	builtinimport.o \
 	vm.o \
diff --git a/py/stream.c b/py/stream.c
new file mode 100644
index 0000000000..82a5aac10b
--- /dev/null
+++ b/py/stream.c
@@ -0,0 +1,55 @@
+#include <string.h>
+
+#include "nlr.h"
+#include "misc.h"
+#include "mpconfig.h"
+#include "mpqstr.h"
+#include "obj.h"
+#include "stream.h"
+
+// This file defines generic Python stream read/write methods which
+// dispatch to the underlying stream interface of an object.
+
+static mp_obj_t stream_read(mp_obj_t self_in, mp_obj_t arg) {
+    struct _mp_obj_base_t *o = (struct _mp_obj_base_t *)self_in;
+    if (o->type->stream_p.read == NULL) {
+        // CPython: io.UnsupportedOperation, OSError subclass
+        nlr_jump(mp_obj_new_exception_msg(MP_QSTR_OSError, "Operation not supported"));
+    }
+
+    machine_int_t sz = mp_obj_get_int(arg);
+    // +1 because so far we mark end of string with \0
+    char *buf = m_new(char, sz + 1);
+    int error;
+    machine_int_t out_sz = o->type->stream_p.read(self_in, buf, sz, &error);
+    if (out_sz == -1) {
+        nlr_jump(mp_obj_new_exception_msg_1_arg(MP_QSTR_OSError, "[Errno %d]", (const char *)error));
+    } else {
+        buf[out_sz] = 0;
+        return mp_obj_new_str(qstr_from_str_take(buf, /*out_sz,*/ sz + 1));
+    }
+}
+
+static mp_obj_t stream_write(mp_obj_t self_in, mp_obj_t arg) {
+    struct _mp_obj_base_t *o = (struct _mp_obj_base_t *)self_in;
+    if (o->type->stream_p.write == NULL) {
+        // CPython: io.UnsupportedOperation, OSError subclass
+        nlr_jump(mp_obj_new_exception_msg(MP_QSTR_OSError, "Operation not supported"));
+    }
+
+    const char *buf = qstr_str(mp_obj_get_qstr(arg));
+    machine_int_t sz = strlen(buf);
+    int error;
+    machine_int_t out_sz = o->type->stream_p.write(self_in, buf, sz, &error);
+    if (out_sz == -1) {
+        nlr_jump(mp_obj_new_exception_msg_1_arg(MP_QSTR_OSError, "[Errno %d]", (const char *)error));
+    } else {
+        // http://docs.python.org/3/library/io.html#io.RawIOBase.write
+        // "None is returned if the raw stream is set not to block and no single byte could be readily written to it."
+        // Do they mean that instead of 0 they return None?
+        return MP_OBJ_NEW_SMALL_INT(out_sz);
+    }
+}
+
+MP_DEFINE_CONST_FUN_OBJ_2(mp_stream_read_obj, stream_read);
+MP_DEFINE_CONST_FUN_OBJ_2(mp_stream_write_obj, stream_write);
diff --git a/py/stream.h b/py/stream.h
new file mode 100644
index 0000000000..8a579b7621
--- /dev/null
+++ b/py/stream.h
@@ -0,0 +1,2 @@
+extern const mp_obj_fun_native_t mp_stream_read_obj;
+extern const mp_obj_fun_native_t mp_stream_write_obj;