Author: Justin Peel <[email protected]>
Branch: faster-str-decode-escape
Changeset: r52927:6f5ea64c8b8d
Date: 2012-02-27 07:55 -0700
http://bitbucket.org/pypy/pypy/changeset/6f5ea64c8b8d/
Log: Try to speed up string's decode escape by using a string builder and
appending unescaped text in slices
diff --git a/pypy/interpreter/pyparser/parsestring.py
b/pypy/interpreter/pyparser/parsestring.py
--- a/pypy/interpreter/pyparser/parsestring.py
+++ b/pypy/interpreter/pyparser/parsestring.py
@@ -115,21 +115,24 @@
the string is UTF-8 encoded and should be re-encoded in the
specified encoding.
"""
- lis = []
+ from pypy.rlib.rstring import StringBuilder
+ builder = StringBuilder(len(s))
ps = 0
end = len(s)
- while ps < end:
- if s[ps] != '\\':
- # note that the C code has a label here.
- # the logic is the same.
+ while 1:
+ ps2 = ps
+ while ps < end and s[ps] != '\\':
if recode_encoding and ord(s[ps]) & 0x80:
w, ps = decode_utf8(space, s, ps, end, recode_encoding)
- # Append bytes to output buffer.
- lis.append(w)
+ builder.append(w)
+ ps2 = ps
else:
- lis.append(s[ps])
ps += 1
- continue
+ if ps > ps2:
+ builder.append_slice(s, ps2, ps)
+ if ps == end:
+ break
+
ps += 1
if ps == end:
raise_app_valueerror(space, 'Trailing \\ in string')
@@ -140,25 +143,25 @@
if ch == '\n':
pass
elif ch == '\\':
- lis.append('\\')
+ builder.append('\\')
elif ch == "'":
- lis.append("'")
+ builder.append("'")
elif ch == '"':
- lis.append('"')
+ builder.append('"')
elif ch == 'b':
- lis.append("\010")
+ builder.append("\010")
elif ch == 'f':
- lis.append('\014') # FF
+ builder.append('\014') # FF
elif ch == 't':
- lis.append('\t')
+ builder.append('\t')
elif ch == 'n':
- lis.append('\n')
+ builder.append('\n')
elif ch == 'r':
- lis.append('\r')
+ builder.append('\r')
elif ch == 'v':
- lis.append('\013') # VT
+ builder.append('\013') # VT
elif ch == 'a':
- lis.append('\007') # BEL, not classic C
+ builder.append('\007') # BEL, not classic C
elif ch in '01234567':
# Look for up to two more octal digits
span = ps
@@ -168,13 +171,13 @@
# emulate a strange wrap-around behavior of CPython:
# \400 is the same as \000 because 0400 == 256
num = int(octal, 8) & 0xFF
- lis.append(chr(num))
+ builder.append(chr(num))
ps = span
elif ch == 'x':
if ps+2 <= end and isxdigit(s[ps]) and isxdigit(s[ps + 1]):
hexa = s[ps : ps + 2]
num = int(hexa, 16)
- lis.append(chr(num))
+ builder.append(chr(num))
ps += 2
else:
raise_app_valueerror(space, 'invalid \\x escape')
@@ -184,13 +187,13 @@
# this was not an escape, so the backslash
# has to be added, and we start over in
# non-escape mode.
- lis.append('\\')
+ builder.append('\\')
ps -= 1
assert ps >= 0
continue
# an arbitry number of unescaped UTF-8 bytes may follow.
- buf = ''.join(lis)
+ buf = builder.build()
return buf
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