Add as_slice method for all string nodes (#9111)

This PR adds a `as_slice` method to all the string nodes which returns
all the parts of the nodes as a slice. This will be useful in the next
PR to split the string formatting to use this method to extract the
_single node_ or _implicitly concanated nodes_.

crates/ruff_linter/src/checkers/ast/analyze/expression.rs

@@ -1277,7 +1277,7 @@ pub(crate) fn expression(expr: &Expr, checker: &mut Checker) {
         }
         Expr::StringLiteral(ast::ExprStringLiteral { value, .. }) => {
             if checker.enabled(Rule::UnicodeKindPrefix) {
-                for string_part in value.parts() {
+                for string_part in value {
                     pyupgrade::rules::unicode_kind_prefix(checker, string_part);
                 }
             }

crates/ruff_linter/src/rules/flake8_bandit/rules/hardcoded_sql_expression.rs

@@ -57,7 +57,7 @@ impl Violation for HardcodedSQLExpression {
 /// becomes `foobar {x}baz`.
 fn concatenated_f_string(expr: &ast::ExprFString, locator: &Locator) -> String {
     expr.value
-        .parts()
+        .iter()
         .filter_map(|part| {
             raw_contents(locator.slice(part)).map(|s| s.escape_default().to_string())
         })

crates/ruff_linter/src/rules/flake8_pytest_style/rules/helpers.rs

@@ -56,7 +56,7 @@ pub(super) fn is_empty_or_null_string(expr: &Expr) -> bool {
         Expr::StringLiteral(ast::ExprStringLiteral { value, .. }) => value.is_empty(),
         Expr::NoneLiteral(_) => true,
         Expr::FString(ast::ExprFString { value, .. }) => {
-            value.parts().all(|f_string_part| match f_string_part {
+            value.iter().all(|f_string_part| match f_string_part {
                 ast::FStringPart::Literal(literal) => literal.is_empty(),
                 ast::FStringPart::FString(f_string) => f_string
                     .elements

crates/ruff_linter/src/rules/pylint/rules/assert_on_string_literal.rs

@@ -70,7 +70,7 @@ pub(crate) fn assert_on_string_literal(checker: &mut Checker, test: &Expr) {
             ));
         }
         Expr::FString(ast::ExprFString { value, .. }) => {
-            let kind = if value.parts().all(|f_string_part| match f_string_part {
+            let kind = if value.iter().all(|f_string_part| match f_string_part {
                 ast::FStringPart::Literal(literal) => literal.is_empty(),
                 ast::FStringPart::FString(f_string) => {
                     f_string.elements.iter().all(|element| match element {
@@ -82,7 +82,7 @@ pub(crate) fn assert_on_string_literal(checker: &mut Checker, test: &Expr) {
                 }
             }) {
                 Kind::Empty
-            } else if value.parts().any(|f_string_part| match f_string_part {
+            } else if value.iter().any(|f_string_part| match f_string_part {
                 ast::FStringPart::Literal(literal) => !literal.is_empty(),
                 ast::FStringPart::FString(f_string) => {
                     f_string.elements.iter().any(|element| match element {

crates/ruff_linter/src/rules/tryceratops/rules/raise_vanilla_args.rs

@@ -90,7 +90,7 @@ pub(crate) fn raise_vanilla_args(checker: &mut Checker, expr: &Expr) {
 fn contains_message(expr: &Expr) -> bool {
     match expr {
         Expr::FString(ast::ExprFString { value, .. }) => {
-            for f_string_part in value.parts() {
+            for f_string_part in value {
                 match f_string_part {
                     ast::FStringPart::Literal(literal) => {
                         if literal.chars().any(char::is_whitespace) {

crates/ruff_python_ast/src/comparable.rs

@@ -583,10 +583,10 @@ impl<'a> From<ast::LiteralExpressionRef<'a>> for ComparableLiteral<'a> {
                 value, ..
             }) => Self::Bool(value),
             ast::LiteralExpressionRef::StringLiteral(ast::ExprStringLiteral { value, .. }) => {
-                Self::Str(value.parts().map(Into::into).collect())
+                Self::Str(value.iter().map(Into::into).collect())
             }
             ast::LiteralExpressionRef::BytesLiteral(ast::ExprBytesLiteral { value, .. }) => {
-                Self::Bytes(value.parts().map(Into::into).collect())
+                Self::Bytes(value.iter().map(Into::into).collect())
             }
             ast::LiteralExpressionRef::NumberLiteral(ast::ExprNumberLiteral { value, .. }) => {
                 Self::Number(value.into())
@@ -1012,17 +1012,17 @@ impl<'a> From<&'a ast::Expr> for ComparableExpr<'a> {
             }),
             ast::Expr::FString(ast::ExprFString { value, range: _ }) => {
                 Self::FString(ExprFString {
-                    parts: value.parts().map(Into::into).collect(),
+                    parts: value.iter().map(Into::into).collect(),
                 })
             }
             ast::Expr::StringLiteral(ast::ExprStringLiteral { value, range: _ }) => {
                 Self::StringLiteral(ExprStringLiteral {
-                    parts: value.parts().map(Into::into).collect(),
+                    parts: value.iter().map(Into::into).collect(),
                 })
             }
             ast::Expr::BytesLiteral(ast::ExprBytesLiteral { value, range: _ }) => {
                 Self::BytesLiteral(ExprBytesLiteral {
-                    parts: value.parts().map(Into::into).collect(),
+                    parts: value.iter().map(Into::into).collect(),
                 })
             }
             ast::Expr::NumberLiteral(ast::ExprNumberLiteral { value, range: _ }) => {

crates/ruff_python_ast/src/helpers.rs

@@ -1326,7 +1326,7 @@ impl Truthiness {
             Expr::NoneLiteral(_) => Self::Falsey,
             Expr::EllipsisLiteral(_) => Self::Truthy,
             Expr::FString(ast::ExprFString { value, .. }) => {
-                if value.parts().all(|part| match part {
+                if value.iter().all(|part| match part {
                     ast::FStringPart::Literal(string_literal) => string_literal.is_empty(),
                     ast::FStringPart::FString(f_string) => f_string.elements.is_empty(),
                 }) {

crates/ruff_python_ast/src/node.rs

@@ -2742,7 +2742,7 @@ impl AstNode for ast::ExprFString {
     {
         let ast::ExprFString { value, range: _ } = self;
 
-        for f_string_part in value.parts() {
+        for f_string_part in value {
             match f_string_part {
                 ast::FStringPart::Literal(string_literal) => {
                     visitor.visit_string_literal(string_literal);
@@ -2788,7 +2788,7 @@ impl AstNode for ast::ExprStringLiteral {
     {
         let ast::ExprStringLiteral { value, range: _ } = self;
 
-        for string_literal in value.parts() {
+        for string_literal in value {
             visitor.visit_string_literal(string_literal);
         }
     }
@@ -2827,7 +2827,7 @@ impl AstNode for ast::ExprBytesLiteral {
     {
         let ast::ExprBytesLiteral { value, range: _ } = self;
 
-        for bytes_literal in value.parts() {
+        for bytes_literal in value {
             visitor.visit_bytes_literal(bytes_literal);
         }
     }

crates/ruff_python_ast/src/nodes.rs

@@ -4,8 +4,8 @@ use std::cell::OnceCell;
 use std::fmt;
 use std::fmt::Debug;
 use std::ops::Deref;
+use std::slice::{Iter, IterMut};
 
-use itertools::Either::{Left, Right};
 use itertools::Itertools;
 
 use ruff_text_size::{Ranged, TextRange, TextSize};
@@ -1051,23 +1051,33 @@ impl FStringValue {
         matches!(self.inner, FStringValueInner::Concatenated(_))
     }
 
-    /// Returns an iterator over all the [`FStringPart`]s contained in this value.
-    pub fn parts(&self) -> impl Iterator<Item = &FStringPart> {
+    /// Returns a slice of all the [`FStringPart`]s contained in this value.
+    pub fn as_slice(&self) -> &[FStringPart] {
         match &self.inner {
-            FStringValueInner::Single(part) => Left(std::iter::once(part)),
-            FStringValueInner::Concatenated(parts) => Right(parts.iter()),
+            FStringValueInner::Single(part) => std::slice::from_ref(part),
+            FStringValueInner::Concatenated(parts) => parts,
         }
     }
 
-    /// Returns an iterator over all the [`FStringPart`]s contained in this value
-    /// that allows modification.
-    pub(crate) fn parts_mut(&mut self) -> impl Iterator<Item = &mut FStringPart> {
+    /// Returns a mutable slice of all the [`FStringPart`]s contained in this value.
+    fn as_mut_slice(&mut self) -> &mut [FStringPart] {
         match &mut self.inner {
-            FStringValueInner::Single(part) => Left(std::iter::once(part)),
-            FStringValueInner::Concatenated(parts) => Right(parts.iter_mut()),
+            FStringValueInner::Single(part) => std::slice::from_mut(part),
+            FStringValueInner::Concatenated(parts) => parts,
         }
     }
 
+    /// Returns an iterator over all the [`FStringPart`]s contained in this value.
+    pub fn iter(&self) -> Iter<FStringPart> {
+        self.as_slice().iter()
+    }
+
+    /// Returns an iterator over all the [`FStringPart`]s contained in this value
+    /// that allows modification.
+    pub(crate) fn iter_mut(&mut self) -> IterMut<FStringPart> {
+        self.as_mut_slice().iter_mut()
+    }
+
     /// Returns an iterator over the [`StringLiteral`] parts contained in this value.
     ///
     /// Note that this doesn't nest into the f-string parts. For example,
@@ -1078,7 +1088,7 @@ impl FStringValue {
     ///
     /// Here, the string literal parts returned would be `"foo"` and `"baz"`.
     pub fn literals(&self) -> impl Iterator<Item = &StringLiteral> {
-        self.parts().filter_map(|part| part.as_literal())
+        self.iter().filter_map(|part| part.as_literal())
     }
 
     /// Returns an iterator over the [`FString`] parts contained in this value.
@@ -1091,7 +1101,7 @@ impl FStringValue {
     ///
     /// Here, the f-string parts returned would be `f"bar {x}"` and `f"qux"`.
     pub fn f_strings(&self) -> impl Iterator<Item = &FString> {
-        self.parts().filter_map(|part| part.as_f_string())
+        self.iter().filter_map(|part| part.as_f_string())
     }
 
     /// Returns an iterator over all the [`FStringElement`] contained in this value.
@@ -1110,6 +1120,15 @@ impl FStringValue {
     }
 }
 
+impl<'a> IntoIterator for &'a FStringValue {
+    type Item = &'a FStringPart;
+    type IntoIter = Iter<'a, FStringPart>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
+    }
+}
+
 /// An internal representation of [`FStringValue`].
 #[derive(Clone, Debug, PartialEq)]
 enum FStringValueInner {
@@ -1238,26 +1257,36 @@ impl StringLiteralValue {
     /// For an implicitly concatenated string, it returns `true` only if the first
     /// string literal is a unicode string.
     pub fn is_unicode(&self) -> bool {
-        self.parts().next().map_or(false, |part| part.unicode)
+        self.iter().next().map_or(false, |part| part.unicode)
     }
 
-    /// Returns an iterator over all the [`StringLiteral`] parts contained in this value.
-    pub fn parts(&self) -> impl Iterator<Item = &StringLiteral> {
+    /// Returns a slice of all the [`StringLiteral`] parts contained in this value.
+    pub fn as_slice(&self) -> &[StringLiteral] {
         match &self.inner {
-            StringLiteralValueInner::Single(value) => Left(std::iter::once(value)),
-            StringLiteralValueInner::Concatenated(value) => Right(value.strings.iter()),
+            StringLiteralValueInner::Single(value) => std::slice::from_ref(value),
+            StringLiteralValueInner::Concatenated(value) => value.strings.as_slice(),
         }
     }
 
-    /// Returns an iterator over all the [`StringLiteral`] parts contained in this value
-    /// that allows modification.
-    pub(crate) fn parts_mut(&mut self) -> impl Iterator<Item = &mut StringLiteral> {
+    /// Returns a mutable slice of all the [`StringLiteral`] parts contained in this value.
+    fn as_mut_slice(&mut self) -> &mut [StringLiteral] {
         match &mut self.inner {
-            StringLiteralValueInner::Single(value) => Left(std::iter::once(value)),
-            StringLiteralValueInner::Concatenated(value) => Right(value.strings.iter_mut()),
+            StringLiteralValueInner::Single(value) => std::slice::from_mut(value),
+            StringLiteralValueInner::Concatenated(value) => value.strings.as_mut_slice(),
         }
     }
 
+    /// Returns an iterator over all the [`StringLiteral`] parts contained in this value.
+    pub fn iter(&self) -> Iter<StringLiteral> {
+        self.as_slice().iter()
+    }
+
+    /// Returns an iterator over all the [`StringLiteral`] parts contained in this value
+    /// that allows modification.
+    pub(crate) fn iter_mut(&mut self) -> IterMut<StringLiteral> {
+        self.as_mut_slice().iter_mut()
+    }
+
     /// Returns `true` if the string literal value is empty.
     pub fn is_empty(&self) -> bool {
         self.len() == 0
@@ -1266,12 +1295,12 @@ impl StringLiteralValue {
     /// Returns the total length of the string literal value, in bytes, not
     /// [`char`]s or graphemes.
     pub fn len(&self) -> usize {
-        self.parts().fold(0, |acc, part| acc + part.value.len())
+        self.iter().fold(0, |acc, part| acc + part.value.len())
     }
 
     /// Returns an iterator over the [`char`]s of each string literal part.
     pub fn chars(&self) -> impl Iterator<Item = char> + '_ {
-        self.parts().flat_map(|part| part.value.chars())
+        self.iter().flat_map(|part| part.value.chars())
     }
 
     /// Returns the concatenated string value as a [`str`].
@@ -1286,6 +1315,15 @@ impl StringLiteralValue {
     }
 }
 
+impl<'a> IntoIterator for &'a StringLiteralValue {
+    type Item = &'a StringLiteral;
+    type IntoIter = Iter<'a, StringLiteral>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
+    }
+}
+
 impl PartialEq<str> for StringLiteralValue {
     fn eq(&self, other: &str) -> bool {
         if self.len() != other.len() {
@@ -1457,37 +1495,55 @@ impl BytesLiteralValue {
         matches!(self.inner, BytesLiteralValueInner::Concatenated(_))
     }
 
-    /// Returns an iterator over all the [`BytesLiteral`] parts contained in this value.
-    pub fn parts(&self) -> impl Iterator<Item = &BytesLiteral> {
+    /// Returns a slice of all the [`BytesLiteral`] parts contained in this value.
+    pub fn as_slice(&self) -> &[BytesLiteral] {
         match &self.inner {
-            BytesLiteralValueInner::Single(value) => Left(std::iter::once(value)),
-            BytesLiteralValueInner::Concatenated(values) => Right(values.iter()),
+            BytesLiteralValueInner::Single(value) => std::slice::from_ref(value),
+            BytesLiteralValueInner::Concatenated(value) => value.as_slice(),
         }
     }
 
-    /// Returns an iterator over all the [`BytesLiteral`] parts contained in this value
-    /// that allows modification.
-    pub(crate) fn parts_mut(&mut self) -> impl Iterator<Item = &mut BytesLiteral> {
+    /// Returns a mutable slice of all the [`BytesLiteral`] parts contained in this value.
+    fn as_mut_slice(&mut self) -> &mut [BytesLiteral] {
         match &mut self.inner {
-            BytesLiteralValueInner::Single(value) => Left(std::iter::once(value)),
-            BytesLiteralValueInner::Concatenated(values) => Right(values.iter_mut()),
+            BytesLiteralValueInner::Single(value) => std::slice::from_mut(value),
+            BytesLiteralValueInner::Concatenated(value) => value.as_mut_slice(),
         }
     }
 
+    /// Returns an iterator over all the [`BytesLiteral`] parts contained in this value.
+    pub fn iter(&self) -> Iter<BytesLiteral> {
+        self.as_slice().iter()
+    }
+
+    /// Returns an iterator over all the [`BytesLiteral`] parts contained in this value
+    /// that allows modification.
+    pub(crate) fn iter_mut(&mut self) -> IterMut<BytesLiteral> {
+        self.as_mut_slice().iter_mut()
+    }
+
     /// Returns `true` if the concatenated bytes has a length of zero.
     pub fn is_empty(&self) -> bool {
-        self.parts().all(|part| part.is_empty())
+        self.iter().all(|part| part.is_empty())
     }
 
     /// Returns the length of the concatenated bytes.
     pub fn len(&self) -> usize {
-        self.parts().map(|part| part.len()).sum()
+        self.iter().map(|part| part.len()).sum()
     }
 
     /// Returns an iterator over the bytes of the concatenated bytes.
     fn bytes(&self) -> impl Iterator<Item = u8> + '_ {
-        self.parts()
-            .flat_map(|part| part.as_slice().iter().copied())
+        self.iter().flat_map(|part| part.as_slice().iter().copied())
+    }
+}
+
+impl<'a> IntoIterator for &'a BytesLiteralValue {
+    type Item = &'a BytesLiteral;
+    type IntoIter = Iter<'a, BytesLiteral>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
     }
 }
 

crates/ruff_python_ast/src/visitor.rs

@@ -477,7 +477,7 @@ pub fn walk_expr<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, expr: &'a Expr) {
             visitor.visit_arguments(arguments);
         }
         Expr::FString(ast::ExprFString { value, .. }) => {
-            for part in value.parts() {
+            for part in value {
                 match part {
                     FStringPart::Literal(string_literal) => {
                         visitor.visit_string_literal(string_literal);
@@ -487,12 +487,12 @@ pub fn walk_expr<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, expr: &'a Expr) {
             }
         }
         Expr::StringLiteral(ast::ExprStringLiteral { value, .. }) => {
-            for string_literal in value.parts() {
+            for string_literal in value {
                 visitor.visit_string_literal(string_literal);
             }
         }
         Expr::BytesLiteral(ast::ExprBytesLiteral { value, .. }) => {
-            for bytes_literal in value.parts() {
+            for bytes_literal in value {
                 visitor.visit_bytes_literal(bytes_literal);
             }
         }