Library import 16 (#2433)

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1 files changed, 194 insertions, 0 deletions

diff --git a/contrib/tools/python3/Lib/linecache.py b/contrib/tools/python3/Lib/linecache.py
new file mode 100644
index 0000000000..b164e727c6
--- /dev/null
+++ b/contrib/tools/python3/Lib/linecache.py
@@ -0,0 +1,194 @@
+"""Cache lines from Python source 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 functools
+import sys
+import os
+import tokenize
+
+__all__ = ["getline", "clearcache", "checkcache", "lazycache"]
+
+
+# The cache. Maps filenames to either a thunk which will provide source code,
+# or a tuple (size, mtime, lines, fullname) once loaded.
+cache = {}
+
+
+def clearcache():
+    """Clear the cache entirely."""
+    cache.clear()
+
+
+def getline(filename, lineno, module_globals=None):
+    """Get a line for a Python source file from the cache.
+    Update the cache if it doesn't contain an entry for this file already."""
+
+    lines = getlines(filename, module_globals)
+    if 1 <= lineno <= len(lines):
+        return lines[lineno - 1]
+    return ''
+
+
+def getlines(filename, module_globals=None):
+    """Get the lines for a Python source file from the cache.
+    Update the cache if it doesn't contain an entry for this file already."""
+
+    if filename in cache:
+        entry = cache[filename]
+        if len(entry) != 1:
+            return cache[filename][2]
+
+    try:
+        return updatecache(filename, module_globals)
+    except MemoryError:
+        clearcache()
+        return []
+
+
+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+    """Discard cache entries that are out of date.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())
+    elif filename in cache:
+        filenames = [filename]
+    else:
+        return
+
+    for filename in filenames:
+        entry = cache[filename]
+        if len(entry) == 1:
+            # lazy cache entry, leave it lazy.
+            continue
+        size, mtime, lines, fullname = entry
+        if mtime is None:
+            continue   # no-op for files loaded via a __loader__
+        try:
+            stat = os.stat(fullname)
+        except OSError:
+            cache.pop(filename, None)
+            continue
+        if size != stat.st_size or mtime != stat.st_mtime:
+            cache.pop(filename, None)
+
+
+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:
+        if len(cache[filename]) != 1:
+            cache.pop(filename, None)
+    if not filename or (filename.startswith('<') and filename.endswith('>')):
+        return []
+
+    if not os.path.isabs(filename):
+        # Do not read builtin code from the filesystem.
+        import __res
+
+        key = __res.py_src_key(filename)
+        if data := __res.resfs_read(key):
+            assert data is not None, filename
+            data = data.decode('UTF-8')
+            lines = [line + '\n' for line in data.splitlines()]
+            cache[filename] = (len(data), None, lines, filename)
+            return cache[filename][2]
+
+    fullname = filename
+    try:
+        stat = os.stat(fullname)
+    except OSError:
+        basename = filename
+
+        # Realise a lazy loader based lookup if there is one
+        # otherwise try to lookup right now.
+        if lazycache(filename, module_globals):
+            try:
+                data = cache[filename][0]()
+            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, UnicodeDecodeError, SyntaxError):
+        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
+
+
+def lazycache(filename, module_globals):
+    """Seed the cache for filename with module_globals.
+
+    The module loader will be asked for the source only when getlines is
+    called, not immediately.
+
+    If there is an entry in the cache already, it is not altered.
+
+    :return: True if a lazy load is registered in the cache,
+        otherwise False. To register such a load a module loader with a
+        get_source method must be found, the filename must be a cacheable
+        filename, and the filename must not be already cached.
+    """
+    if filename in cache:
+        if len(cache[filename]) == 1:
+            return True
+        else:
+            return False
+    if not filename or (filename.startswith('<') and filename.endswith('>')):
+        return False
+    # Try for a __loader__, if available
+    if module_globals and '__name__' in module_globals:
+        name = module_globals['__name__']
+        if (loader := module_globals.get('__loader__')) is None:
+            if spec := module_globals.get('__spec__'):
+                try:
+                    loader = spec.loader
+                except AttributeError:
+                    pass
+        get_source = getattr(loader, 'get_source', None)
+
+        if name and get_source:
+            get_lines = functools.partial(get_source, name)
+            cache[filename] = (get_lines,)
+            return True
+    return False