py: Allow lexer to raise exceptions during construction.

This patch refactors the error handling in the lexer, to simplify it (ie
reduce code size).

A long time ago, when the lexer/parser/compiler were first written, the
lexer and parser were designed so they didn't use exceptions (ie nlr) to
report errors but rather returned an error code.  Over time that has
gradually changed, the parser in particular has more and more ways of
raising exceptions.  Also, the lexer never really handled all errors without
raising, eg there were some memory errors which could raise an exception
(and in these rare cases one would get a fatal nlr-not-handled fault).

This patch accepts the fact that the lexer can raise exceptions in some
cases and allows it to raise exceptions to handle all its errors, which are
for the most part just out-of-memory errors during construction of the
lexer.  This makes the lexer a bit simpler, and also the persistent code
stuff is simplified.

What this means for users of the lexer is that calls to it must be wrapped
in a nlr handler.  But all uses of the lexer already have such an nlr
handler for the parser (and compiler) so that doesn't put any extra burden
on the callers.

extmod/vfs_reader.c

@@ -27,7 +27,7 @@
 #include <stdio.h>
 #include <string.h>
 
-#include "py/nlr.h"
+#include "py/runtime.h"
 #include "py/stream.h"
 #include "py/reader.h"
 #include "extmod/vfs.h"
@@ -69,30 +69,19 @@ STATIC void mp_reader_vfs_close(void *data) {
     m_del_obj(mp_reader_vfs_t, reader);
 }
 
-int mp_reader_new_file(mp_reader_t *reader, const char *filename) {
+void mp_reader_new_file(mp_reader_t *reader, const char *filename) {
-    mp_reader_vfs_t *rf = m_new_obj_maybe(mp_reader_vfs_t);
+    mp_reader_vfs_t *rf = m_new_obj(mp_reader_vfs_t);
-    if (rf == NULL) {
+    mp_obj_t arg = mp_obj_new_str(filename, strlen(filename), false);
-        return MP_ENOMEM;
+    rf->file = mp_vfs_open(1, &arg, (mp_map_t*)&mp_const_empty_map);
-    }
+    int errcode;
-    // TODO we really should just let this function raise a uPy exception
+    rf->len = mp_stream_rw(rf->file, rf->buf, sizeof(rf->buf), &errcode, MP_STREAM_RW_READ | MP_STREAM_RW_ONCE);
-    nlr_buf_t nlr;
+    if (errcode != 0) {
-    if (nlr_push(&nlr) == 0) {
+        mp_raise_OSError(errcode);
-        mp_obj_t arg = mp_obj_new_str(filename, strlen(filename), false);
-        rf->file = mp_vfs_open(1, &arg, (mp_map_t*)&mp_const_empty_map);
-        int errcode;
-        rf->len = mp_stream_rw(rf->file, rf->buf, sizeof(rf->buf), &errcode, MP_STREAM_RW_READ | MP_STREAM_RW_ONCE);
-        nlr_pop();
-        if (errcode != 0) {
-            return errcode;
-        }
-    } else {
-        return MP_ENOENT; // assume error was "file not found"
     }
     rf->pos = 0;
     reader->data = rf;
     reader->readbyte = mp_reader_vfs_readbyte;
     reader->close = mp_reader_vfs_close;
-    return 0; // success
 }
 
 #endif // MICROPY_READER_VFS

py/builtinevex.c

@@ -136,9 +136,6 @@ STATIC mp_obj_t eval_exec_helper(size_t n_args, const mp_obj_t *args, mp_parse_i
     mp_lexer_t *lex;
     if (MICROPY_PY_BUILTINS_EXECFILE && parse_input_kind == MP_PARSE_SINGLE_INPUT) {
         lex = mp_lexer_new_from_file(str);
-        if (lex == NULL) {
-            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError, "could not open file '%s'", str));
-        }
         parse_input_kind = MP_PARSE_FILE_INPUT;
     } else {
         lex = mp_lexer_new_from_str_len(MP_QSTR__lt_string_gt_, str, str_len, 0);

py/builtinimport.c

@@ -131,18 +131,7 @@ STATIC mp_import_stat_t find_file(const char *file_str, uint file_len, vstr_t *d
 }
 
 #if MICROPY_ENABLE_COMPILER
-STATIC void do_load_from_lexer(mp_obj_t module_obj, mp_lexer_t *lex, const char *fname) {
+STATIC void do_load_from_lexer(mp_obj_t module_obj, mp_lexer_t *lex) {
-
-    if (lex == NULL) {
-        // we verified the file exists using stat, but lexer could still fail
-        if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            mp_raise_msg(&mp_type_ImportError, "module not found");
-        } else {
-            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ImportError,
-                "no module named '%s'", fname));
-        }
-    }
-
     #if MICROPY_PY___FILE__
     qstr source_name = lex->source_name;
     mp_store_attr(module_obj, MP_QSTR___file__, MP_OBJ_NEW_QSTR(source_name));
@@ -207,7 +196,7 @@ STATIC void do_load(mp_obj_t module_obj, vstr_t *file) {
     // found the filename in the list of frozen files, then load and execute it.
     #if MICROPY_MODULE_FROZEN_STR
     if (frozen_type == MP_FROZEN_STR) {
-        do_load_from_lexer(module_obj, modref, file_str);
+        do_load_from_lexer(module_obj, modref);
         return;
     }
     #endif
@@ -235,7 +224,7 @@ STATIC void do_load(mp_obj_t module_obj, vstr_t *file) {
     #if MICROPY_ENABLE_COMPILER
     {
         mp_lexer_t *lex = mp_lexer_new_from_file(file_str);
-        do_load_from_lexer(module_obj, lex, file_str);
+        do_load_from_lexer(module_obj, lex);
         return;
     }
     #endif

py/lexer.c

@@ -699,13 +699,7 @@ void mp_lexer_to_next(mp_lexer_t *lex) {
 }
 
 mp_lexer_t *mp_lexer_new(qstr src_name, mp_reader_t reader) {
-    mp_lexer_t *lex = m_new_obj_maybe(mp_lexer_t);
+    mp_lexer_t *lex = m_new_obj(mp_lexer_t);
-
-    // check for memory allocation error
-    if (lex == NULL) {
-        reader.close(reader.data);
-        return NULL;
-    }
 
     lex->source_name = src_name;
     lex->reader = reader;
@@ -715,16 +709,9 @@ mp_lexer_t *mp_lexer_new(qstr src_name, mp_reader_t reader) {
     lex->nested_bracket_level = 0;
     lex->alloc_indent_level = MICROPY_ALLOC_LEXER_INDENT_INIT;
     lex->num_indent_level = 1;
-    lex->indent_level = m_new_maybe(uint16_t, lex->alloc_indent_level);
+    lex->indent_level = m_new(uint16_t, lex->alloc_indent_level);
     vstr_init(&lex->vstr, 32);
 
-    // check for memory allocation error
-    // note: vstr_init above may fail on malloc, but so may mp_lexer_to_next below
-    if (lex->indent_level == NULL) {
-        mp_lexer_free(lex);
-        return NULL;
-    }
-
     // store sentinel for first indentation level
     lex->indent_level[0] = 0;
 
@@ -764,9 +751,7 @@ mp_lexer_t *mp_lexer_new(qstr src_name, mp_reader_t reader) {
 
 mp_lexer_t *mp_lexer_new_from_str_len(qstr src_name, const char *str, size_t len, size_t free_len) {
     mp_reader_t reader;
-    if (!mp_reader_new_mem(&reader, (const byte*)str, len, free_len)) {
+    mp_reader_new_mem(&reader, (const byte*)str, len, free_len);
-        return NULL;
-    }
     return mp_lexer_new(src_name, reader);
 }
 
@@ -774,10 +759,7 @@ mp_lexer_t *mp_lexer_new_from_str_len(qstr src_name, const char *str, size_t len
 
 mp_lexer_t *mp_lexer_new_from_file(const char *filename) {
     mp_reader_t reader;
-    int ret = mp_reader_new_file(&reader, filename);
+    mp_reader_new_file(&reader, filename);
-    if (ret != 0) {
-        return NULL;
-    }
     return mp_lexer_new(qstr_from_str(filename), reader);
 }
 
@@ -785,10 +767,7 @@ mp_lexer_t *mp_lexer_new_from_file(const char *filename) {
 
 mp_lexer_t *mp_lexer_new_from_fd(qstr filename, int fd, bool close_fd) {
     mp_reader_t reader;
-    int ret = mp_reader_new_file_from_fd(&reader, fd, close_fd);
+    mp_reader_new_file_from_fd(&reader, fd, close_fd);
-    if (ret != 0) {
-        return NULL;
-    }
     return mp_lexer_new(filename, reader);
 }
 

py/persistentcode.c

@@ -225,18 +225,13 @@ mp_raw_code_t *mp_raw_code_load(mp_reader_t *reader) {
 
 mp_raw_code_t *mp_raw_code_load_mem(const byte *buf, size_t len) {
     mp_reader_t reader;
-    if (!mp_reader_new_mem(&reader, buf, len, 0)) {
+    mp_reader_new_mem(&reader, buf, len, 0);
-        m_malloc_fail(BYTES_PER_WORD); // we need to raise a MemoryError
-    }
     return mp_raw_code_load(&reader);
 }
 
 mp_raw_code_t *mp_raw_code_load_file(const char *filename) {
     mp_reader_t reader;
-    int ret = mp_reader_new_file(&reader, filename);
+    mp_reader_new_file(&reader, filename);
-    if (ret != 0) {
-        mp_raise_OSError(ret);
-    }
     return mp_raw_code_load(&reader);
 }
 

py/reader.c

@@ -27,6 +27,7 @@
 #include <stdio.h>
 #include <assert.h>
 
+#include "py/runtime.h"
 #include "py/mperrno.h"
 #include "py/reader.h"
 
@@ -54,11 +55,8 @@ STATIC void mp_reader_mem_close(void *data) {
     m_del_obj(mp_reader_mem_t, reader);
 }
 
-bool mp_reader_new_mem(mp_reader_t *reader, const byte *buf, size_t len, size_t free_len) {
+void mp_reader_new_mem(mp_reader_t *reader, const byte *buf, size_t len, size_t free_len) {
-    mp_reader_mem_t *rm = m_new_obj_maybe(mp_reader_mem_t);
+    mp_reader_mem_t *rm = m_new_obj(mp_reader_mem_t);
-    if (rm == NULL) {
-        return false;
-    }
     rm->free_len = free_len;
     rm->beg = buf;
     rm->cur = buf;
@@ -66,7 +64,6 @@ bool mp_reader_new_mem(mp_reader_t *reader, const byte *buf, size_t len, size_t
     reader->data = rm;
     reader->readbyte = mp_reader_mem_readbyte;
     reader->close = mp_reader_mem_close;
-    return true;
 }
 
 #if MICROPY_READER_POSIX
@@ -110,14 +107,8 @@ STATIC void mp_reader_posix_close(void *data) {
     m_del_obj(mp_reader_posix_t, reader);
 }
 
-int mp_reader_new_file_from_fd(mp_reader_t *reader, int fd, bool close_fd) {
+void mp_reader_new_file_from_fd(mp_reader_t *reader, int fd, bool close_fd) {
-    mp_reader_posix_t *rp = m_new_obj_maybe(mp_reader_posix_t);
+    mp_reader_posix_t *rp = m_new_obj(mp_reader_posix_t);
-    if (rp == NULL) {
-        if (close_fd) {
-            close(fd);
-        }
-        return MP_ENOMEM;
-    }
     rp->close_fd = close_fd;
     rp->fd = fd;
     int n = read(rp->fd, rp->buf, sizeof(rp->buf));
@@ -125,22 +116,21 @@ int mp_reader_new_file_from_fd(mp_reader_t *reader, int fd, bool close_fd) {
         if (close_fd) {
             close(fd);
         }
-        return errno;
+        mp_raise_OSError(errno);
     }
     rp->len = n;
     rp->pos = 0;
     reader->data = rp;
     reader->readbyte = mp_reader_posix_readbyte;
     reader->close = mp_reader_posix_close;
-    return 0; // success
 }
 
-int mp_reader_new_file(mp_reader_t *reader, const char *filename) {
+void mp_reader_new_file(mp_reader_t *reader, const char *filename) {
     int fd = open(filename, O_RDONLY, 0644);
     if (fd < 0) {
-        return errno;
+        mp_raise_OSError(errno);
     }
-    return mp_reader_new_file_from_fd(reader, fd, true);
+    mp_reader_new_file_from_fd(reader, fd, true);
 }
 
 #endif

py/reader.h

@@ -39,8 +39,8 @@ typedef struct _mp_reader_t {
     void (*close)(void *data);
 } mp_reader_t;
 
-bool mp_reader_new_mem(mp_reader_t *reader, const byte *buf, size_t len, size_t free_len);
+void mp_reader_new_mem(mp_reader_t *reader, const byte *buf, size_t len, size_t free_len);
-int mp_reader_new_file(mp_reader_t *reader, const char *filename);
+void mp_reader_new_file(mp_reader_t *reader, const char *filename);
-int mp_reader_new_file_from_fd(mp_reader_t *reader, int fd, bool close_fd);
+void mp_reader_new_file_from_fd(mp_reader_t *reader, int fd, bool close_fd);
 
 #endif // MICROPY_INCLUDED_PY_READER_H