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Merged
merged 1 commit into from
Dec 24, 2019
Merged

Add str.format_map method #1639

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62 changes: 61 additions & 1 deletion tests/snippets/strings.py
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
from testutils import assert_raises
from testutils import assert_raises, AssertRaises

assert "".__eq__(1) == NotImplemented
assert "a" == 'a'
Expand Down Expand Up @@ -338,3 +338,63 @@ def try_mutate_str():
assert "1a".islower()
assert "가나다a".islower()
assert "가나다A".isupper()

# test str.format_map()
#
# The following tests were performed in Python 3.7.5:
# Python 3.7.5 (default, Dec 19 2019, 17:11:32)
# [GCC 5.4.0 20160609] on linux

# >>> '{x} {y}'.format_map({'x': 1, 'y': 2})
# '1 2'
assert '{x} {y}'.format_map({'x': 1, 'y': 2}) == '1 2'

# >>> '{x:04d}'.format_map({'x': 1})
# '0001'
assert '{x:04d}'.format_map({'x': 1}) == '0001'

# >>> '{x} {y}'.format_map('foo')
# Traceback (most recent call last):
# File "<stdin>", line 1, in <module>
# TypeError: string indices must be integers
with AssertRaises(TypeError, None):
'{x} {y}'.format_map('foo')

# >>> '{x} {y}'.format_map(['foo'])
# Traceback (most recent call last):
# File "<stdin>", line 1, in <module>
# TypeError: list indices must be integers or slices, not str
with AssertRaises(TypeError, None):
'{x} {y}'.format_map(['foo'])

# >>> '{x} {y}'.format_map()
# Traceback (most recent call last):
# File "<stdin>", line 1, in <module>
# TypeError: format_map() takes exactly one argument (0 given)
with AssertRaises(TypeError, msg='TypeError: format_map() takes exactly one argument (0 given)'):
'{x} {y}'.format_map(),

# >>> '{x} {y}'.format_map('foo', 'bar')
# Traceback (most recent call last):
# File "<stdin>", line 1, in <module>
# TypeError: format_map() takes exactly one argument (2 given)
with AssertRaises(TypeError, msg='TypeError: format_map() takes exactly one argument (2 given)'):
'{x} {y}'.format_map('foo', 'bar')

# >>> '{x} {y}'.format_map({'x': 1})
# Traceback (most recent call last):
# File "<stdin>", line 1, in <module>
# KeyError: 'y'
with AssertRaises(KeyError, msg="KeyError: 'y'"):
'{x} {y}'.format_map({'x': 1})

# >>> '{x} {y}'.format_map({'x': 1, 'z': 2})
# Traceback (most recent call last):
# File "<stdin>", line 1, in <module>
# KeyError: 'y'
with AssertRaises(KeyError, msg="KeyError: 'y'"):
'{x} {y}'.format_map({'x': 1, 'z': 2})

# >>> '{{literal}}'.format_map('foo')
# '{literal}'
assert '{{literal}}'.format_map('foo') == '{literal}'
51 changes: 51 additions & 0 deletions vm/src/obj/objstr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -651,6 +651,32 @@ impl PyString {
}
}

/// S.format_map(mapping) -> str
///
/// Return a formatted version of S, using substitutions from mapping.
/// The substitutions are identified by braces ('{' and '}').
#[pymethod]
fn format_map(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
if args.args.len() != 2 {
return Err(vm.new_type_error(format!(
"format_map() takes exactly one argument ({} given)",
args.args.len() - 1
)));
}

let zelf = &args.args[0];
let format_string_text = get_value(zelf);
match FormatString::from_str(format_string_text.as_str()) {
Ok(format_string) => perform_format_map(vm, &format_string, &args.args[1]),
Err(err) => match err {
FormatParseError::UnmatchedBracket => {
Err(vm.new_value_error("expected '}' before end of string".to_string()))
}
_ => Err(vm.new_value_error("Unexpected error parsing format string".to_string())),
},
}
}

/// Return a titlecased version of the string where words start with an
/// uppercase character and the remaining characters are lowercase.
#[pymethod]
Expand Down Expand Up @@ -1590,6 +1616,31 @@ fn perform_format(
Ok(vm.ctx.new_str(final_string))
}

fn perform_format_map(
vm: &VirtualMachine,
format_string: &FormatString,
dict: &PyObjectRef,
) -> PyResult {
let mut final_string = String::new();
for part in &format_string.format_parts {
let result_string: String = match part {
FormatPart::AutoSpec(_) | FormatPart::IndexSpec(_, _) => {
return Err(
vm.new_value_error("Format string contains positional fields".to_string())
);
}
FormatPart::KeywordSpec(keyword, format_spec) => {
let argument = dict.get_item(keyword, &vm)?;
let result = call_object_format(vm, argument.clone(), &format_spec)?;
get_value(&result)
}
FormatPart::Literal(literal) => literal.clone(),
};
final_string.push_str(&result_string);
}
Ok(vm.ctx.new_str(final_string))
}

impl PySliceableSequence for String {
type Sliced = String;

Expand Down