8000 Preallocate strings in a smarter way + add str.rmul by Jongy · Pull Request #913 · RustPython/RustPython · GitHub
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Preallocate strings in a smarter way + add str.rmul #913

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Merged
merged 4 commits into from
May 7, 2019
Merged

Preallocate strings in a smarter way + add str.rmul #913

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a118497
Preallocate cloned strings with the minimum expected length
Jongy May 2, 2019
f12268f
Implement str.__rmul__
Jongy May 2, 2019
d1730a5
Add basic string multiplication tests
Jongy May 3, 2019
857a701
Enable and extend strings/membership tests
Jongy May 3, 2019
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15 changes: 8 additions & 7 deletions tests/snippets/membership.py
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Original file line number Diff line number Diff line change
Expand Up @@ -12,9 +12,8 @@
assert "whatever" not in "foobar"

# test bytes
# TODO: uncomment this when bytes are implemented
# assert b"foo" in b"foobar"
# assert b"whatever" not in b"foobar"
assert b"foo" in b"foobar"
assert b"whatever" not in b"foobar"
assert b"1" < b"2"
assert b"1" <= b"2"
assert b"5" <= b"5"
Expand All @@ -32,18 +31,20 @@
assert 3 not in set([1, 2])

# test dicts
# TODO: test dicts when keys other than strings will be allowed
assert "a" in {"a": 0, "b": 0}
assert "c" not in {"a": 0, "b": 0}
assert 1 in {1: 5, 7: 12}
assert 5 not in {9: 10, 50: 100}
assert True in {True: 5}
assert False not in {True: 5}

# test iter
assert 3 in iter([1, 2, 3])
assert 3 not in iter([1, 2])

# test sequence
# TODO: uncomment this when ranges are usable
# assert 1 in range(0, 2)
# assert 3 not in range(0, 2)
assert 1 in range(0, 2)
assert 3 not in range(0, 2)

# test __contains__ in user objects
class MyNotContainingClass():
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9 changes: 9 additions & 0 deletions tests/snippets/strings.py
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Expand Up @@ -29,6 +29,14 @@

assert str(["a", "b", "can't"]) == "['a', 'b', \"can't\"]"

assert "xy" * 3 == "xyxyxy"
assert "x" * 0 == ""
assert "x" * -1 == ""

assert 3 * "xy" == "xyxyxy"
assert 0 * "x" == ""
assert -1 * "x" == ""

a = 'Hallo'
assert a.lower() == 'hallo'
assert a.upper() == 'HALLO'
Expand Down Expand Up @@ -94,6 +102,7 @@
]


# requires CPython 3.7, and the CI currently runs with 3.6
# assert c.isascii()
assert c.index('a') == 1
assert c.rindex('l') == 3
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16 changes: 13 additions & 3 deletions vm/src/obj/objstr.rs
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Expand Up @@ -183,7 +183,12 @@ impl PyString {
if objtype::isinstance(&val, &vm.ctx.int_type()) {
let value = &self.value;
let multiplier = objint::get_value(&val).to_i32().unwrap();
let mut result = String::new();
let capacity = if multiplier > 0 {
multiplier.to_usize().unwrap() * value.len()
} else {
0
};
let mut result = String::with_capacity(capacity);
for _x in 0..multiplier {
result.push_str(value.as_str());
}
Expand All @@ -193,6 +198,11 @@ impl PyString {
}
}

#[pymethod(name = "__rmul__")]
fn rmul(&self, val: PyObjectRef, vm: &VirtualMachine) -> PyResult<String> {
self.mul(val, vm)
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Downside with this simple impl is that the raised TypeError shows the values swapped (As per the order of __mul__, not __rmul__).

On the other hand, the shown message (still?) doesn't match the one given by CPython, so we can be less pedantic about it.

}

#[pymethod(name = "__str__")]
fn str(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyStringRef {
zelf
Expand All @@ -206,7 +216,7 @@ impl PyString {
} else {
'\''
};
let mut formatted = String::new();
let mut formatted = String::with_capacity(value.len());
formatted.push(quote_char);
for c in value.chars() {
if c == quote_char || c == '\\' {
Expand Down Expand Up @@ -799,7 +809,7 @@ impl PyString {
#[pymethod]
fn expandtabs(&self, tab_stop: OptionalArg<usize>, _vm: &VirtualMachine) -> String {
let tab_stop = tab_stop.into_option().unwrap_or(8 as usize);
let mut expanded_str = String::new();
let mut expanded_str = String::with_capacity(self.value.len());
let mut tab_size = tab_stop;
let mut col_count = 0 as usize;
for ch in self.value.chars() {
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