Mercurial > hg
view mercurial/diffhelpers.c @ 29375:fcaf20175b1b
demandimport: delay loading for "from a import b" with absolute_import
Before this patch, "from a import b" doesn't delay loading module "b",
if absolute_import is enabled, even though "from . import b" does.
For example:
- it is assumed that extension X has "from P import M" for module M
under package P with absolute_import feature
- if importing module M is already delayed before loading extension
X, loading module M in extension X is delayed until actually
referring
util, cmdutil, scmutil or so of Mercurial itself should be
imported by "from . import M" style before loading extension X
- otherwise, module M is loaded immediately at loading extension X,
even if extension X itself isn't used at that "hg" command invocation
Some minor modules (e.g. filemerge or so) of Mercurial itself
aren't imported by "from . import M" style before loading
extension X. And of course, external libraries aren't, too.
This might cause startup performance problem of hg command, because
many bundled extensions already enable absolute_import feature.
To delay loading module for "from a import b" with absolute_import
feature, this patch does below in "from a (or .a) import b" with
absolute_import case:
1. import root module of "name" by system built-in __import__
(referred as _origimport)
2. recurse down the module chain for hierarchical "name"
This logic can be shared with non absolute_import
case. Therefore, this patch also centralizes it into chainmodules().
3. and fall through to process elements in "fromlist" for the leaf
module of "name"
Processing elements in "fromlist" is executed in the code path
after "if _pypy: .... else: ..." clause. Therefore, this patch
replaces "if _pypy:" with "elif _pypy:" to share it.
At 4f1144c3c72b introducing original "work around" for "from a import
b" case, elements in "fromlist" were imported with "level=level". But
"level" might be grater than 1 (e.g. level=2 in "from .. import b"
case) at demandimport() invocation, and importing direct sub-module in
"fromlist" with level grater than 1 causes unexpected result.
IMHO, this seems main reason of "errors for unknown reason" described
in 4f1144c3c72b, and we don't have to worry about it, because this
issue was already fixed by 78d05778907b.
This is reason why this patch removes "errors for unknown reasons"
comment.
author | FUJIWARA Katsunori <foozy@lares.dti.ne.jp> |
---|---|
date | Sun, 19 Jun 2016 02:17:33 +0900 |
parents | f1c127df7c4f |
children | 2f51f4c535d2 |
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line source
/* * diffhelpers.c - helper routines for mpatch * * Copyright 2007 Chris Mason <chris.mason@oracle.com> * * This software may be used and distributed according to the terms * of the GNU General Public License v2, incorporated herein by reference. */ #include <Python.h> #include <stdlib.h> #include <string.h> #include "util.h" static char diffhelpers_doc[] = "Efficient diff parsing"; static PyObject *diffhelpers_Error; /* fixup the last lines of a and b when the patch has no newline at eof */ static void _fix_newline(PyObject *hunk, PyObject *a, PyObject *b) { Py_ssize_t hunksz = PyList_Size(hunk); PyObject *s = PyList_GET_ITEM(hunk, hunksz-1); char *l = PyBytes_AsString(s); Py_ssize_t alen = PyList_Size(a); Py_ssize_t blen = PyList_Size(b); char c = l[0]; PyObject *hline; Py_ssize_t sz = PyBytes_GET_SIZE(s); if (sz > 1 && l[sz-2] == '\r') /* tolerate CRLF in last line */ sz -= 1; hline = PyBytes_FromStringAndSize(l, sz-1); if (!hline) { return; } if (c == ' ' || c == '+') { PyObject *rline = PyBytes_FromStringAndSize(l + 1, sz - 2); PyList_SetItem(b, blen-1, rline); } if (c == ' ' || c == '-') { Py_INCREF(hline); PyList_SetItem(a, alen-1, hline); } PyList_SetItem(hunk, hunksz-1, hline); } /* python callable form of _fix_newline */ static PyObject * fix_newline(PyObject *self, PyObject *args) { PyObject *hunk, *a, *b; if (!PyArg_ParseTuple(args, "OOO", &hunk, &a, &b)) return NULL; _fix_newline(hunk, a, b); return Py_BuildValue("l", 0); } #if (PY_VERSION_HEX < 0x02050000) static const char *addlines_format = "OOiiOO"; #else static const char *addlines_format = "OOnnOO"; #endif /* * read lines from fp into the hunk. The hunk is parsed into two arrays * a and b. a gets the old state of the text, b gets the new state * The control char from the hunk is saved when inserting into a, but not b * (for performance while deleting files) */ static PyObject * addlines(PyObject *self, PyObject *args) { PyObject *fp, *hunk, *a, *b, *x; Py_ssize_t i; Py_ssize_t lena, lenb; Py_ssize_t num; Py_ssize_t todoa, todob; char *s, c; PyObject *l; if (!PyArg_ParseTuple(args, addlines_format, &fp, &hunk, &lena, &lenb, &a, &b)) return NULL; while (1) { todoa = lena - PyList_Size(a); todob = lenb - PyList_Size(b); num = todoa > todob ? todoa : todob; if (num == 0) break; for (i = 0; i < num; i++) { x = PyFile_GetLine(fp, 0); s = PyBytes_AsString(x); c = *s; if (strcmp(s, "\\ No newline at end of file\n") == 0) { _fix_newline(hunk, a, b); continue; } if (c == '\n') { /* Some patches may be missing the control char * on empty lines. Supply a leading space. */ Py_DECREF(x); x = PyBytes_FromString(" \n"); } PyList_Append(hunk, x); if (c == '+') { l = PyBytes_FromString(s + 1); PyList_Append(b, l); Py_DECREF(l); } else if (c == '-') { PyList_Append(a, x); } else { l = PyBytes_FromString(s + 1); PyList_Append(b, l); Py_DECREF(l); PyList_Append(a, x); } Py_DECREF(x); } } return Py_BuildValue("l", 0); } /* * compare the lines in a with the lines in b. a is assumed to have * a control char at the start of each line, this char is ignored in the * compare */ static PyObject * testhunk(PyObject *self, PyObject *args) { PyObject *a, *b; long bstart; Py_ssize_t alen, blen; Py_ssize_t i; char *sa, *sb; if (!PyArg_ParseTuple(args, "OOl", &a, &b, &bstart)) return NULL; alen = PyList_Size(a); blen = PyList_Size(b); if (alen > blen - bstart || bstart < 0) { return Py_BuildValue("l", -1); } for (i = 0; i < alen; i++) { sa = PyBytes_AsString(PyList_GET_ITEM(a, i)); sb = PyBytes_AsString(PyList_GET_ITEM(b, i + bstart)); if (strcmp(sa + 1, sb) != 0) return Py_BuildValue("l", -1); } return Py_BuildValue("l", 0); } static PyMethodDef methods[] = { {"addlines", addlines, METH_VARARGS, "add lines to a hunk\n"}, {"fix_newline", fix_newline, METH_VARARGS, "fixup newline counters\n"}, {"testhunk", testhunk, METH_VARARGS, "test lines in a hunk\n"}, {NULL, NULL} }; #ifdef IS_PY3K static struct PyModuleDef diffhelpers_module = { PyModuleDef_HEAD_INIT, "diffhelpers", diffhelpers_doc, -1, methods }; PyMODINIT_FUNC PyInit_diffhelpers(void) { PyObject *m; m = PyModule_Create(&diffhelpers_module); if (m == NULL) return NULL; diffhelpers_Error = PyErr_NewException("diffhelpers.diffhelpersError", NULL, NULL); Py_INCREF(diffhelpers_Error); PyModule_AddObject(m, "diffhelpersError", diffhelpers_Error); return m; } #else PyMODINIT_FUNC initdiffhelpers(void) { Py_InitModule3("diffhelpers", methods, diffhelpers_doc); diffhelpers_Error = PyErr_NewException("diffhelpers.diffhelpersError", NULL, NULL); } #endif