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# quoting.py
"""Various helpers for string quoting/unquoting."""
import urllib, re
from skytools.psycopgwrapper import QuotedString
__all__ = [
"quote_literal", "quote_copy", "quote_bytea_raw",
"quote_bytea_literal", "quote_bytea_copy", "quote_statement",
"quote_ident", "quote_fqident", "quote_json",
"db_urlencode", "db_urldecode", "unescape", "unescape_copy"
]
#
# SQL quoting
#
def quote_literal(s):
"""Quote a literal value for SQL.
Surronds it with single-quotes.
"""
if s == None:
return "null"
s = QuotedString(str(s))
return str(s)
def quote_copy(s):
"""Quoting for copy command."""
if s == None:
return "\\N"
s = str(s)
s = s.replace("\\", "\\\\")
s = s.replace("\t", "\\t")
s = s.replace("\n", "\\n")
s = s.replace("\r", "\\r")
return s
def quote_bytea_raw(s):
"""Quoting for bytea parser."""
if s == None:
return None
return s.replace("\\", "\\\\").replace("\0", "\\000")
def quote_bytea_literal(s):
"""Quote bytea for regular SQL."""
return quote_literal(quote_bytea_raw(s))
def quote_bytea_copy(s):
"""Quote bytea for COPY."""
return quote_copy(quote_bytea_raw(s))
def quote_statement(sql, dict):
"""Quote whole statement.
Data values are taken from dict.
"""
xdict = {}
for k, v in dict.items():
xdict[k] = quote_literal(v)
return sql % xdict
# reserved keywords
_ident_kwmap = {
"all":1, "analyse":1, "analyze":1, "and":1, "any":1, "array":1, "as":1,
"asc":1, "asymmetric":1, "both":1, "case":1, "cast":1, "check":1, "collate":1,
"column":1, "constraint":1, "create":1, "current_date":1, "current_role":1,
"current_time":1, "current_timestamp":1, "current_user":1, "default":1,
"deferrable":1, "desc":1, "distinct":1, "do":1, "else":1, "end":1, "except":1,
"false":1, "for":1, "foreign":1, "from":1, "grant":1, "group":1, "having":1,
"in":1, "initially":1, "intersect":1, "into":1, "leading":1, "limit":1,
"localtime":1, "localtimestamp":1, "new":1, "not":1, "null":1, "off":1,
"offset":1, "old":1, "on":1, "only":1, "or":1, "order":1, "placing":1,
"primary":1, "references":1, "returning":1, "select":1, "session_user":1,
"some":1, "symmetric":1, "table":1, "then":1, "to":1, "trailing":1, "true":1,
"union":1, "unique":1, "user":1, "using":1, "when":1, "where":1,
}
_ident_bad = re.compile(r"[^a-z0-9_]")
def quote_ident(s):
"""Quote SQL identifier.
If is checked against weird symbols and keywords.
"""
if _ident_bad.search(s) or s in _ident_kwmap:
s = '"%s"' % s.replace('"', '""')
return s
def quote_fqident(s):
"""Quote fully qualified SQL identifier.
The '.' is taken as namespace separator and
all parts are quoted separately
"""
return '.'.join(map(quote_ident, s.split('.')))
#
# quoting for JSON strings
#
_jsre = re.compile(r'[\x00-\x1F\\/"]')
_jsmap = { "\b": "\\b", "\f": "\\f", "\n": "\\n", "\r": "\\r",
"\t": "\\t", "\\": "\\\\", '"': '\\"',
"/": "\\/", # to avoid html attacks
}
def _json_quote_char(m):
c = m.group(0)
try:
return _jsmap[c]
except KeyError:
return r"\u%04x" % ord(c)
def quote_json(s):
"""JSON style quoting."""
if s is None:
return "null"
return '"%s"' % _jsre.sub(_json_quote_char, s)
#
# Database specific urlencode and urldecode.
#
def db_urlencode(dict):
"""Database specific urlencode.
Encode None as key without '='. That means that in "foo&bar=",
foo is NULL and bar is empty string.
"""
elem_list = []
for k, v in dict.items():
if v is None:
elem = urllib.quote_plus(str(k))
else:
elem = urllib.quote_plus(str(k)) + '=' + urllib.quote_plus(str(v))
elem_list.append(elem)
return '&'.join(elem_list)
def db_urldecode(qs):
"""Database specific urldecode.
Decode key without '=' as None.
This also does not support one key several times.
"""
res = {}
for elem in qs.split('&'):
if not elem:
continue
pair = elem.split('=', 1)
name = urllib.unquote_plus(pair[0])
if len(pair) == 1:
res[name] = None
else:
res[name] = urllib.unquote_plus(pair[1])
return res
#
# Remove C-like backslash escapes
#
_esc_re = r"\\([0-7][0-7][0-7]|.)"
_esc_rc = re.compile(_esc_re)
_esc_map = {
't': '\t',
'n': '\n',
'r': '\r',
'a': '\a',
'b': '\b',
"'": "'",
'"': '"',
'\\': '\\',
}
def _sub_unescape(m):
v = m.group(1)
if len(v) == 1:
return _esc_map[v]
else:
return chr(int(v, 8))
def unescape(val):
"""Removes C-style escapes from string."""
return _esc_rc.sub(_sub_unescape, val)
def unescape_copy(val):
"""Removes C-style escapes, also converts "\N" to None."""
if val == r"\N":
return None
return unescape(val)
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