Add _PyUnicodeWriter_WriteSubstring() function
Write a function to enable more optimizations:
* If the substring is the whole string and overallocation is disabled, just
keep a reference to the string, don't copy characters
* Avoid a call to the expensive _PyUnicode_FindMaxChar() function when
possible
diff --git a/Include/unicodeobject.h b/Include/unicodeobject.h
index a70585c..0917307 100644
--- a/Include/unicodeobject.h
+++ b/Include/unicodeobject.h
@@ -940,6 +940,15 @@
PyObject *str /* Unicode string */
);
+/* Append a substring of a Unicode string.
+ Return 0 on success, raise an exception and return -1 on error. */
+PyAPI_FUNC(int)
+_PyUnicodeWriter_WriteSubstring(_PyUnicodeWriter *writer,
+ PyObject *str, /* Unicode string */
+ Py_ssize_t start,
+ Py_ssize_t end
+ );
+
/* Append a latin1-encoded byte string.
Return 0 on success, raise an exception and return -1 on error. */
PyAPI_FUNC(int)
diff --git a/Lib/test/test_format.py b/Lib/test/test_format.py
index bc56fbc..bbce970 100644
--- a/Lib/test/test_format.py
+++ b/Lib/test/test_format.py
@@ -324,6 +324,9 @@
self.assertIs("{0:1s}".format(text), text)
self.assertIs("{0:5s}".format(text), text)
+ self.assertIs(text % (), text)
+ self.assertIs(text.format(), text)
+
def test_main():
support.run_unittest(FormatTest)
diff --git a/Objects/stringlib/unicode_format.h b/Objects/stringlib/unicode_format.h
index e9be516..2f58946 100644
--- a/Objects/stringlib/unicode_format.h
+++ b/Objects/stringlib/unicode_format.h
@@ -869,25 +869,19 @@
SubString literal;
SubString field_name;
SubString format_spec;
- Py_UCS4 conversion, maxchar;
- Py_ssize_t sublen;
- int err;
+ Py_UCS4 conversion;
MarkupIterator_init(&iter, input->str, input->start, input->end);
while ((result = MarkupIterator_next(&iter, &literal, &field_present,
&field_name, &format_spec,
&conversion,
&format_spec_needs_expanding)) == 2) {
- sublen = literal.end - literal.start;
- if (sublen) {
- maxchar = _PyUnicode_FindMaxChar(literal.str,
- literal.start, literal.end);
- err = _PyUnicodeWriter_Prepare(writer, sublen, maxchar);
- if (err == -1)
+ if (literal.end != literal.start) {
+ if (!field_present && iter.str.start == iter.str.end)
+ writer->overallocate = 0;
+ if (_PyUnicodeWriter_WriteSubstring(writer, literal.str,
+ literal.start, literal.end) < 0)
return 0;
- _PyUnicode_FastCopyCharacters(writer->buffer, writer->pos,
- literal.str, literal.start, sublen);
- writer->pos += sublen;
}
if (field_present) {
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 23e57f0..a926e37 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -12791,6 +12791,41 @@
}
int
+_PyUnicodeWriter_WriteSubstring(_PyUnicodeWriter *writer, PyObject *str,
+ Py_ssize_t start, Py_ssize_t end)
+{
+ Py_UCS4 maxchar;
+ Py_ssize_t len;
+
+ if (PyUnicode_READY(str) == -1)
+ return -1;
+
+ assert(0 <= start);
+ assert(end <= PyUnicode_GET_LENGTH(str));
+ assert(start <= end);
+
+ if (end == 0)
+ return 0;
+
+ if (start == 0 && end == PyUnicode_GET_LENGTH(str))
+ return _PyUnicodeWriter_WriteStr(writer, str);
+
+ if (PyUnicode_MAX_CHAR_VALUE(str) > writer->maxchar)
+ maxchar = _PyUnicode_FindMaxChar(str, start, end);
+ else
+ maxchar = writer->maxchar;
+ len = end - start;
+
+ if (_PyUnicodeWriter_Prepare(writer, len, maxchar) < 0)
+ return -1;
+
+ _PyUnicode_FastCopyCharacters(writer->buffer, writer->pos,
+ str, start, len);
+ writer->pos += len;
+ return 0;
+}
+
+int
_PyUnicodeWriter_WriteCstr(_PyUnicodeWriter *writer, const char *str, Py_ssize_t len)
{
Py_UCS4 maxchar;
@@ -13963,7 +13998,7 @@
while (--ctx.fmtcnt >= 0) {
if (PyUnicode_READ(ctx.fmtkind, ctx.fmtdata, ctx.fmtpos) != '%') {
- Py_ssize_t nonfmtpos, sublen;
+ Py_ssize_t nonfmtpos;
Py_UCS4 maxchar;
nonfmtpos = ctx.fmtpos++;
@@ -13976,15 +14011,10 @@
ctx.fmtpos--;
ctx.writer.overallocate = 0;
}
- sublen = ctx.fmtpos - nonfmtpos;
- maxchar = _PyUnicode_FindMaxChar(ctx.fmtstr,
- nonfmtpos, nonfmtpos + sublen);
- if (_PyUnicodeWriter_Prepare(&ctx.writer, sublen, maxchar) == -1)
- goto onError;
- _PyUnicode_FastCopyCharacters(ctx.writer.buffer, ctx.writer.pos,
- ctx.fmtstr, nonfmtpos, sublen);
- ctx.writer.pos += sublen;
+ if (_PyUnicodeWriter_WriteSubstring(&ctx.writer, ctx.fmtstr,
+ nonfmtpos, ctx.fmtpos) < 0)
+ goto onError;
}
else {
ctx.fmtpos++;