Backport linecache for Python 2.6 and up.

Author: rbtcollins

linecache2/__init__.py

@@ -0,0 +1,260 @@
+"""Cache lines from files.
+
+This is intended to read lines from modules imported -- hence if a filename
+is not found, it will look down the module search path for a file by
+that name.
+"""
+
+import io
+import sys
+import os
+import tokenize
+
+__all__ = ["getline", "clearcache", "checkcache"]
+
+def getline(filename, lineno, module_globals=None):
+    lines = getlines(filename, module_globals)
+    if 1 <= lineno <= len(lines):
+        return lines[lineno-1]
+    else:
+        return ''
+
+
+# The cache
+
+cache = {} # The cache
+
+
+def clearcache():
+    """Clear the cache entirely."""
+
+    global cache
+    cache = {}
+
+
+def getlines(filename, module_globals=None):
+    """Get the lines for a file from the cache.
+    Update the cache if it doesn't contain an entry for this file already."""
+
+    if filename in cache:
+        return cache[filename][2]
+    else:
+        return updatecache(filename, module_globals)
+
+
+def checkcache(filename=None):
+    """Discard cache entries that are out of date.
+    (This is not checked upon each call!)"""
+
+    if filename is None:
+        filenames = list(cache.keys())
+    else:
+        if filename in cache:
+            filenames = [filename]
+        else:
+            return
+
+    for filename in filenames:
+        size, mtime, lines, fullname = cache[filename]
+        if mtime is None:
+            continue   # no-op for files loaded via a __loader__
+        try:
+            stat = os.stat(fullname)
+        except OSError:
+            del cache[filename]
+            continue
+        if size != stat.st_size or mtime != stat.st_mtime:
+            del cache[filename]
+
+
+def updatecache(filename, module_globals=None):
+    """Update a cache entry and return its list of lines.
+    If something's wrong, print a message, discard the cache entry,
+    and return an empty list."""
+
+    if filename in cache:
+        del cache[filename]
+    if not filename or (filename.startswith('<') and filename.endswith('>')):
+        return []
+
+    fullname = filename
+    try:
+        stat = os.stat(fullname)
+    except OSError:
+        basename = filename
+
+        # Try for a __loader__, if available
+        if module_globals and '__loader__' in module_globals:
+            name = module_globals.get('__name__')
+            loader = module_globals['__loader__']
+            get_source = getattr(loader, 'get_source', None)
+
+            if name and get_source:
+                try:
+                    data = get_source(name)
+                except (ImportError, OSError):
+                    pass
+                else:
+                    if data is None:
+                        # No luck, the PEP302 loader cannot find the source
+                        # for this module.
+                        return []
+                    cache[filename] = (
+                        len(data), None,
+                        [line+'\n' for line in data.splitlines()], fullname
+                    )
+                    return cache[filename][2]
+
+        # Try looking through the module search path, which is only useful
+        # when handling a relative filename.
+        if os.path.isabs(filename):
+            return []
+
+        for dirname in sys.path:
+            try:
+                fullname = os.path.join(dirname, basename)
+            except (TypeError, AttributeError):
+                # Not sufficiently string-like to do anything useful with.
+                continue
+            try:
+                stat = os.stat(fullname)
+                break
+            except OSError:
+                pass
+        else:
+            return []
+    try:
+        with _tokenize_open(fullname) as fp:
+            lines = fp.readlines()
+    except OSError:
+        return []
+    if lines and not lines[-1].endswith('\n'):
+        lines[-1] += '\n'
+    size, mtime = stat.st_size, stat.st_mtime
+    cache[filename] = size, mtime, lines, fullname
+    return lines
+
+#### ---- avoiding having a tokenize2 backport for now ----
+from codecs import lookup, BOM_UTF8
+import re
+cookie_re = re.compile(r'^[ \t\f]*#.*coding[:=][ \t]*([-\w.]+)'.encode('utf8'))
+blank_re = re.compile(r'^[ \t\f]*(?:[#\r\n]|$)'.encode('utf8'))
+
+
+def _tokenize_open(filename):
+    """Open a file in read only mode using the encoding detected by
+    detect_encoding().
+    """
+    buffer = io.open(filename, 'rb')
+    encoding, lines = _detect_encoding(buffer.readline)
+    buffer.seek(0)
+    text = io.TextIOWrapper(buffer, encoding, line_buffering=True)
+    text.mode = 'r'
+    return text
+
+
+def _get_normal_name(orig_enc):
+    """Imitates get_normal_name in tokenizer.c."""
+    # Only care about the first 12 characters.
+    enc = orig_enc[:12].lower().replace("_", "-")
+    if enc == "utf-8" or enc.startswith("utf-8-"):
+        return "utf-8"
+    if enc in ("latin-1", "iso-8859-1", "iso-latin-1") or \
+       enc.startswith(("latin-1-", "iso-8859-1-", "iso-latin-1-")):
+        return "iso-8859-1"
+    return orig_enc
+
+
+def _detect_encoding(readline):
+    """
+    The detect_encoding() function is used to detect the encoding that should
+    be used to decode a Python source file.  It requires one argument, readline,
+    in the same way as the tokenize() generator.
+
+    It will call readline a maximum of twice, and return the encoding used
+    (as a string) and a list of any lines (left as bytes) it has read in.
+
+    It detects the encoding from the presence of a utf-8 bom or an encoding
+    cookie as specified in pep-0263.  If both a bom and a cookie are present,
+    but disagree, a SyntaxError will be raised.  If the encoding cookie is an
+    invalid charset, raise a SyntaxError.  Note that if a utf-8 bom is found,
+    'utf-8-sig' is returned.
+
+    If no encoding is specified, then the default of 'utf-8' will be returned.
+    """
+    try:
+        filename = readline.__self__.name
+    except AttributeError:
+        filename = None
+    bom_found = False
+    encoding = None
+    default = 'utf-8'
+    def read_or_stop():
+        try:
+            return readline()
+        except StopIteration:
+            return b''
+
+    def find_cookie(line):
+        try:
+            # Decode as UTF-8. Either the line is an encoding declaration,
+            # in which case it should be pure ASCII, or it must be UTF-8
+            # per default encoding.
+            line_string = line.decode('utf-8')
+        except UnicodeDecodeError:
+            msg = "invalid or missing encoding declaration"
+            if filename is not None:
+                msg = '{0} for {1!r}'.format(msg, filename)
+            raise SyntaxError(msg)
+
+        match = cookie_re.match(line)
+        if not match:
+            return None
+        encoding = _get_normal_name(match.group(1).decode('utf-8'))
+        try:
+            codec = lookup(encoding)
+        except LookupError:
+            # This behaviour mimics the Python interpreter
+            if filename is None:
+                msg = "unknown encoding: " + encoding
+            else:
+                msg = "unknown encoding for {!r}: {}".format(filename,
+                        encoding)
+            raise SyntaxError(msg)
+
+        if bom_found:
+            if encoding != 'utf-8':
+                # This behaviour mimics the Python interpreter
+                if filename is None:
+                    msg = 'encoding problem: utf-8'
+                else:
+                    msg = 'encoding problem for {!r}: utf-8'.format(filename)
+                raise SyntaxError(msg)
+            encoding += '-sig'
+        return encoding
+
+    first = read_or_stop()
+    if first.startswith(BOM_UTF8):
+        bom_found = True
+        first = first[3:]
+        default = 'utf-8-sig'
+    if not first:
+        return default, []
+
+    encoding = find_cookie(first)
+    if encoding:
+        return encoding, [first]
+    if not blank_re.match(first):
+        return default, [first]
+
+    second = read_or_stop()
+    if not second:
+        return default, [first]
+
+    encoding = find_cookie(second)
+    if encoding:
+        return encoding, [first, second]
+
+    return default, [first, second]
+
+

linecache2/tests/__init__.py

@@ -0,0 +1,58 @@
+# line 1
+'A module docstring.'
+
+import sys, inspect
+# line 5
+
+# line 7
+def spam(a, b, c, d=3, e=4, f=5, *g, **h):
+    eggs(b + d, c + f)
+
+# line 11
+def eggs(x, y):
+    "A docstring."
+    global fr, st
+    fr = inspect.currentframe()
+    st = inspect.stack()
+    p = x
+    q = y / 0
+
+# line 20
+class StupidGit:
+    """A longer,
+
+    indented
+
+    docstring."""
+# line 27
+
+    def abuse(self, a, b, c):
+        """Another
+
+\tdocstring
+
+        containing
+
+\ttabs
+\t
+        """
+        self.argue(a, b, c)
+# line 40
+    def argue(self, a, b, c):
+        try:
+            spam(a, b, c)
+        except:
+            self.ex = sys.exc_info()
+            self.tr = inspect.trace()
+
+# line 48
+class MalodorousPervert(StupidGit):
+    pass
+
+Tit = MalodorousPervert
+
+class ParrotDroppings:
+    pass
+
+class FesteringGob(MalodorousPervert, ParrotDroppings):
+    pass