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Update F541 to use new f-string tokens
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dhruvmanila committed Sep 13, 2023
1 parent f1e192f commit 0cf830d
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Showing 3 changed files with 58 additions and 18 deletions.
1 change: 1 addition & 0 deletions crates/ruff/resources/test/fixtures/pyflakes/F541.py
Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@
""f""
''f""
(""f""r"")
f"{v:{f"0.2f"}}"

# To be fixed
# Error: f-string: single '}' is not allowed at line 41 column 8
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
use ruff_diagnostics::{AlwaysAutofixableViolation, Diagnostic, Edit, Fix};
use ruff_macros::{derive_message_formats, violation};
use ruff_python_ast::{Expr, PySourceType};
use ruff_python_parser::{lexer, AsMode, StringKind, Tok};
use ruff_python_parser::{lexer, AsMode, Tok};
use ruff_source_file::Locator;
use ruff_text_size::{Ranged, TextRange, TextSize};

Expand Down Expand Up @@ -47,31 +47,49 @@ impl AlwaysAutofixableViolation for FStringMissingPlaceholders {
}
}

/// Find f-strings that don't contain any formatted values in an [`FString`].
/// Return an iterator containing a two-element tuple for each f-string in the
/// given [`ExprFString`] expression. The first element of the tuple is the
/// f-string prefix range, and the second element is the entire f-string range.
///
/// For example,
///
/// ```python
/// f"example"
/// ```
///
/// would return `[(0..1, 0..10)]`.
///
/// This function assumes that the given expression is an [`ExprFString`]
/// without any placeholder expressions.
///
/// [`ExprFString`]: `ruff_python_ast::ExprFString`
fn find_useless_f_strings<'a>(
expr: &'a Expr,
locator: &'a Locator,
source_type: PySourceType,
) -> impl Iterator<Item = (TextRange, TextRange)> + 'a {
let contents = locator.slice(expr);
let mut current_f_string_start = TextSize::default();
lexer::lex_starts_at(contents, source_type.as_mode(), expr.start())
.flatten()
.filter_map(|(tok, range)| match tok {
Tok::String {
kind: StringKind::FString | StringKind::RawFString,
..
} => {
let first_char = locator.slice(TextRange::at(range.start(), TextSize::from(1)));
.filter_map(move |(tok, range)| match tok {
Tok::FStringStart => {
current_f_string_start = range.start();
None
}
Tok::FStringEnd => {
let first_char =
locator.slice(TextRange::at(current_f_string_start, TextSize::from(1)));
// f"..." => f_position = 0
// fr"..." => f_position = 0
// rf"..." => f_position = 1
let f_position = u32::from(!(first_char == "f" || first_char == "F"));
Some((
TextRange::at(
range.start() + TextSize::from(f_position),
current_f_string_start + TextSize::from(f_position),
TextSize::from(1),
),
range,
TextRange::new(current_f_string_start, range.end()),
))
}
_ => None,
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Original file line number Diff line number Diff line change
Expand Up @@ -332,7 +332,7 @@ F541.py:40:3: F541 [*] f-string without any placeholders
40 |+"" ""
41 41 | ''f""
42 42 | (""f""r"")
43 43 |
43 43 | f"{v:{f"0.2f"}}"

F541.py:41:3: F541 [*] f-string without any placeholders
|
Expand All @@ -341,6 +341,7 @@ F541.py:41:3: F541 [*] f-string without any placeholders
41 | ''f""
| ^^^ F541
42 | (""f""r"")
43 | f"{v:{f"0.2f"}}"
|
= help: Remove extraneous `f` prefix

Expand All @@ -351,17 +352,16 @@ F541.py:41:3: F541 [*] f-string without any placeholders
41 |-''f""
41 |+''""
42 42 | (""f""r"")
43 43 |
44 44 | # To be fixed
43 43 | f"{v:{f"0.2f"}}"
44 44 |

F541.py:42:4: F541 [*] f-string without any placeholders
|
40 | ""f""
41 | ''f""
42 | (""f""r"")
| ^^^ F541
43 |
44 | # To be fixed
43 | f"{v:{f"0.2f"}}"
|
= help: Remove extraneous `f` prefix

Expand All @@ -371,8 +371,29 @@ F541.py:42:4: F541 [*] f-string without any placeholders
41 41 | ''f""
42 |-(""f""r"")
42 |+("" ""r"")
43 43 |
44 44 | # To be fixed
45 45 | # Error: f-string: single '}' is not allowed at line 41 column 8
43 43 | f"{v:{f"0.2f"}}"
44 44 |
45 45 | # To be fixed

F541.py:43:7: F541 [*] f-string without any placeholders
|
41 | ''f""
42 | (""f""r"")
43 | f"{v:{f"0.2f"}}"
| ^^^^^^^ F541
44 |
45 | # To be fixed
|
= help: Remove extraneous `f` prefix

Fix
40 40 | ""f""
41 41 | ''f""
42 42 | (""f""r"")
43 |-f"{v:{f"0.2f"}}"
43 |+f"{v:{"0.2f"}}"
44 44 |
45 45 | # To be fixed
46 46 | # Error: f-string: single '}' is not allowed at line 41 column 8


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