[tor-commits] [stem/master] Replacing get_entry with ControlLine class
atagar at torproject.org
atagar at torproject.org
Fri Nov 4 17:19:04 UTC 2011
commit 12064b7b9fc4799b50ff83cffbab55829c0e1046
Author: Damian Johnson <atagar at torproject.org>
Date: Fri Nov 4 10:16:28 2011 -0700
Replacing get_entry with ControlLine class
Making a string subclass to help with the parsing of controller output. Most
entries are space separated lists of elements, which this class has functions
to easily parse. For controller messages that don't follow this pattern we can
still treat it as a normal string.
Next is to add header documentation and tests.
---
stem/types.py | 303 ++++++++++++++++++++++++++++++++++++++++++---------------
1 files changed, 224 insertions(+), 79 deletions(-)
diff --git a/stem/types.py b/stem/types.py
index c149b3b..2e1ac91 100644
--- a/stem/types.py
+++ b/stem/types.py
@@ -19,9 +19,12 @@ Version - Tor versioning information.
import re
import socket
+import threading
from stem.util import log
+KEY_ARG = re.compile("^(\S+)=")
+
# Escape sequences from the 'esc_for_log' function of tor's 'common/util.c'.
CONTROL_ESCAPES = {r"\\": "\\", r"\"": "\"", r"\'": "'",
r"\r": "\r", r"\n": "\n", r"\t": "\t"}
@@ -186,8 +189,8 @@ class ControlMessage:
def __iter__(self):
"""
- Provides the content of the message (stripped of status codes and dividers)
- for each component of the message. Ie...
+ Provides ControlLine instances for the content of the message. This is
+ stripped of status codes and dividers, for instance...
250+info/names=
desc/id/* -- Router descriptors by ID.
@@ -203,7 +206,225 @@ class ControlMessage:
"""
for _, _, content in self._parsed_content:
- yield content
+ yield ControlLine(content)
+
+class ControlLine(str):
+ """
+ String subclass that represents a line of controller output. This behaves as
+ a normal string with additional methods for parsing and popping entries from
+ a space delimited series of elements like a stack.
+
+ None of these additional methods effect ourselves as a string (which is still
+ immutable). All methods are thread safe.
+ """
+
+ def __new__(self, value):
+ return str.__new__(self, value)
+
+ def __init__(self, value):
+ self._remainder = value
+ self._remainder_lock = threading.RLock()
+
+ def remainder(self):
+ """
+ Provides our unparsed content. This is an empty string after we've popped
+ all entries.
+
+ Returns:
+ str of the unparsed content
+ """
+
+ return self._remainder
+
+ def is_empty(self):
+ """
+ Checks if we have further content to pop or not.
+
+ Returns:
+ True if we have additional content, False otherwise
+ """
+
+ return self._remainder == ""
+
+ def is_next_quoted(self, escaped = False):
+ """
+ Checks if our next entry is a quoted value or not.
+
+ Arguments:
+ escaped (bool) - unescapes the CONTROL_ESCAPES escape sequences
+
+ Returns:
+ True if the next entry can be parsed as a quoted value, False otherwise
+ """
+
+ start_quote, end_quote = _get_quote_indeces(self._remainder, escaped)
+ return start_quote == 0 and end_quote != -1
+
+ def is_next_mapping(self, quoted = False, escaped = False):
+ """
+ Checks if our next entry is a KEY=VALUE mapping or not.
+
+ Arguments:
+ quoted (bool) - checks that the mapping is to a quoted value
+ escaped (bool) - unescapes the CONTROL_ESCAPES escape sequences
+
+ Returns:
+ True if the next entry can be parsed as a key=value mapping, False
+ otherwise
+ """
+
+ remainder = self._remainder # temp copy to avoid locking
+ key_match = KEY_ARG.match(remainder)
+
+ if key_match and quoted:
+ # checks that we have a quoted value and that it comes after the 'key='
+ start_quote, end_quote = _get_quote_indeces(remainder, escaped)
+ return start_quote == key_match.end() and end_quote != -1
+ elif key_match:
+ return True # we just needed to check for the key
+ else:
+ return False # doesn't start with a key
+
+ def pop(self, quoted = False, escaped = False):
+ """
+ Parses the next space separated entry, removing it and the space from our
+ remaining content. Examples...
+
+ >>> line = ControlLine('"We're all mad here." says the grinning cat.')
+ >>> print line.pop(True)
+ "We're all mad here."
+ >>> print line.pop()
+ "says"
+ >>> print line.remainder()
+ "the grinning cat."
+
+ >>> line = ControlLine('"this has a \\\" and \\\\ in it" foo=bar more_data')
+ >>> print line.pop(True, True)
+ "this has a \" and \\ in it"
+
+ Arguments:
+ quoted (bool) - parses the next entry as a quoted value, removing the
+ quotes
+ escaped (bool) - unescapes the CONTROL_ESCAPES escape sequences
+
+ Returns:
+ str of the next space separated entry
+
+ Raises:
+ ValueError if quoted is True without the value being quoted
+ IndexError if we don't have any remaining content left to parse
+ """
+
+ try:
+ self._remainder_lock.acquire()
+ next_entry, remainder = _parse_entry(self._remainder, quoted, escaped)
+ self._remainder = remainder
+ return next_entry
+ finally:
+ self._remainder_lock.release()
+
+ def pop_mapping(self, quoted = False, escaped = False):
+ """
+ Parses the next space separated entry as a KEY=VALUE mapping, removing it
+ and the space from our remaining content.
+
+ Arguments:
+ quoted (bool) - parses the value as being quoted, removing the quotes
+ escaped (bool) - unescapes the CONTROL_ESCAPES escape sequences
+
+ Returns:
+ tuple of the form (key, value)
+
+ Raises:
+ ValueError if this isn't a KEY=VALUE mapping or if quoted is True without
+ the value being quoted
+ """
+
+ try:
+ self._remainder_lock.acquire()
+ key_match = KEY_ARG.match(self._remainder)
+
+ if not key_match:
+ raise ValueError("the next entry isn't a KEY=VALUE mapping: " + self._remainder)
+
+ # parse off the key
+ key = key_match.groups()[0]
+ remainder = self._remainder[key_match.end():]
+
+ next_entry, remainder = _parse_entry(remainder, quoted, escaped)
+ self._remainder = remainder
+ return (key, next_entry)
+ finally:
+ self._remainder_lock.release()
+
+def _parse_entry(line, quoted, escaped):
+ """
+ Parses the next entry from the given space separated content.
+
+ Arguments:
+ line (str) - content to be parsed
+ quoted (bool) - parses the next entry as a quoted value, removing the
+ quotes
+ escaped (bool) - unescapes the CONTROL_ESCAPES escape sequences
+
+ Returns:
+ tuple of the form (entry, remainder)
+
+ Raises:
+ ValueError if quoted is True without the next value being quoted
+ IndexError if there's nothing to parse from the line
+ """
+
+ if line == "":
+ raise IndexError("no remaining content to parse")
+
+ next_entry, remainder = "", line
+
+ if quoted:
+ # validate and parse the quoted value
+ start_quote, end_quote = _get_quote_indeces(remainder, escaped)
+
+ if start_quote != 0 or end_quote == -1:
+ raise ValueError("the next entry isn't a quoted value: " + line)
+
+ next_entry, remainder = remainder[1 : end_quote], remainder[end_quote + 1:]
+ else:
+ # non-quoted value, just need to check if there's more data afterward
+ if " " in remainder: next_entry, remainder = remainder.split(" ", 1)
+ else: next_entry, remainder = remainder, ""
+
+ if escaped:
+ for esc_sequence, replacement in CONTROL_ESCAPES.items():
+ next_entry = next_entry.replace(esc_sequence, replacement)
+
+ return (next_entry, remainder.lstrip())
+
+def _get_quote_indeces(line, escaped):
+ """
+ Provides the indices of the next two quotes in the given content.
+
+ Arguments:
+ line (str) - content to be parsed
+ escaped (bool) - unescapes the CONTROL_ESCAPES escape sequences
+
+ Returns:
+ tuple of two ints, indices being -1 if a quote doesn't exist
+ """
+
+ indices, quote_index = [], -1
+
+ for _ in range(2):
+ quote_index = line.find("\"", quote_index + 1)
+
+ # if we have escapes then we need to skip any r'\"' entries
+ if escaped:
+ # skip check if index is -1 (no match) or 0 (first character)
+ while quote_index >= 1 and line[quote_index - 1] == "\\":
+ quote_index = line.find("\"", quote_index + 1)
+
+ indices.append(quote_index)
+
+ return tuple(indices)
class Version:
"""
@@ -286,79 +507,3 @@ class Version:
# TODO: version requirements will probably be moved to another module later
REQ_GETINFO_CONFIG_TEXT = Version("0.2.2.7-alpha")
-# TODO: trying this out temporarily to see if it's generally helpful or another
-# parser function would be a better fit
-def get_entry(line, mapping = False, quoted = False, escaped = False):
- """
- Parses a space separated series of entries, providing back a tuple with the
- first entry in the string and the remainder (dropping the space between).
-
- This is meant to be a helper function for stem to parse tor's control
- protocol lines rather than being used directly by this library's users.
-
- Example:
- get_entry('hello there random person') =>
- (None, "hello", "there random person")
- get_entry('version="0.1.2.3"', True, True) =>
- ("version", "0.1.2.3", "")
- get_entry('"this has a \" and \\ in it" foo=bar more_data', False, True, True) =>
- (None, 'this has a " and \ in it', "foo=bar more_data")
-
- Arguments:
- line (str) - string with a space separated series of entries
- mapping (bool) - parses the next entry as a KEY=VALUE entry, if False then
- the 'key' attribute of the returned tuple is None
- quoted (bool) - parses the next entry as a quoted value, removing the
- quotes
- escaped (bool) - unescapes the CONTROL_ESCAPES escape sequences
-
- Returns:
- tuple of the form (key, value, remainder)
-
- Raises:
- ValueError if 'mapping' is True without a '=' or 'quoted' is True without
- the value being quoted
- """
-
- # Start by splitting apart the 'key=everything else' portion. The key
- # shouldn't have any spaces in it.
-
- if mapping:
- key_match = re.match("^(\S+)=", line)
-
- if key_match:
- key = key_match.groups()[0]
- remainder = line[key_match.end():]
- else:
- raise ValueError("mapping doesn't contain a '=': " + line)
- else: key, remainder = None, line
-
- if quoted:
- # Check that we have a starting quote.
- if not remainder.startswith("\""):
- raise ValueError("quoted value doesn't have a leading quote: " + line)
-
- # Finds the ending quote. If we have escapes then we need to skip any '\"'
- # entries.
- end_quote = remainder.find("\"", 1)
-
- if escaped:
- while end_quote != -1 and remainder[end_quote - 1] == "\\":
- end_quote = remainder.find("\"", end_quote + 1)
-
- # Check that we have an ending quote.
- if end_quote == -1:
- raise ValueError("quoted value doesn't have an ending quote: " + line)
-
- value, remainder = remainder[1:end_quote], remainder[end_quote + 1:]
- else:
- # Non-quoted value. Just need to check if there's more data afterward.
- if " " in remainder: value, remainder = remainder.split(" ", 1)
- else: value, remainder = remainder, ""
-
- if escaped:
- for esc_sequence, replacement in CONTROL_ESCAPES.items():
- value = value.replace(esc_sequence, replacement)
-
- return (key, value, remainder.lstrip())
-
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