feat: add hex underscore fmt rule

crates/config/src/fmt.rs

@@ -19,6 +19,8 @@ pub struct FormatterConfig {
     pub quote_style: QuoteStyle,
     /// Style of underscores in number literals
     pub number_underscore: NumberUnderscore,
+    /// Style of underscores in hex literals
+    pub hex_underscore: HexUnderscore,
     /// Style of single line blocks in statements
     pub single_line_statement_blocks: SingleLineBlockStyle,
     /// Print space in state variable, function and modifier `override` attribute
@@ -44,16 +46,70 @@ pub enum IntTypes {
 }
 
 /// Style of underscores in number literals
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, Serialize, Deserialize)]
 #[serde(rename_all = "snake_case")]
 pub enum NumberUnderscore {
+    /// Use the underscores defined in the source code
+    #[default]
+    Preserve,
     /// Remove all underscores
     Remove,
     /// Add an underscore every thousand, if greater than 9999
     /// e.g. 1000 -> 1000 and 10000 -> 10_000
     Thousands,
+}
+
+impl NumberUnderscore {
+    /// Returns true if the option is `Preserve`
+    #[inline]
+    pub fn is_preserve(self) -> bool {
+        matches!(self, NumberUnderscore::Preserve)
+    }
+
+    /// Returns true if the option is `Remove`
+    #[inline]
+    pub fn is_remove(self) -> bool {
+        matches!(self, NumberUnderscore::Remove)
+    }
+
+    /// Returns true if the option is `Remove`
+    #[inline]
+    pub fn is_thousands(self) -> bool {
+        matches!(self, NumberUnderscore::Thousands)
+    }
+}
+
+/// Style of underscores in hex literals
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum HexUnderscore {
     /// Use the underscores defined in the source code
+    #[default]
     Preserve,
+    /// Remove all underscores
+    Remove,
+    /// Add underscore as separator between byte boundaries
+    Bytes,
+}
+
+impl HexUnderscore {
+    /// Returns true if the option is `Preserve`
+    #[inline]
+    pub fn is_preserve(self) -> bool {
+        matches!(self, HexUnderscore::Preserve)
+    }
+
+    /// Returns true if the option is `Remove`
+    #[inline]
+    pub fn is_remove(self) -> bool {
+        matches!(self, HexUnderscore::Remove)
+    }
+
+    /// Returns true if the option is `Remove`
+    #[inline]
+    pub fn is_bytes(self) -> bool {
+        matches!(self, HexUnderscore::Bytes)
+    }
 }
 
 /// Style of string quotes
@@ -114,6 +170,7 @@ impl Default for FormatterConfig {
             multiline_func_header: MultilineFuncHeaderStyle::AttributesFirst,
             quote_style: QuoteStyle::Double,
             number_underscore: NumberUnderscore::Preserve,
+            hex_underscore: HexUnderscore::Preserve,
             single_line_statement_blocks: SingleLineBlockStyle::Preserve,
             override_spacing: false,
             wrap_comments: false,

crates/fmt/src/formatter.rs

@@ -11,10 +11,10 @@ use crate::{
     solang_ext::{pt::*, *},
     string::{QuoteState, QuotedStringExt},
     visit::{Visitable, Visitor},
-    FormatterConfig, InlineConfig, IntTypes, NumberUnderscore,
+    FormatterConfig, InlineConfig, IntTypes,
 };
 use alloy_primitives::Address;
-use foundry_config::fmt::{MultilineFuncHeaderStyle, SingleLineBlockStyle};
+use foundry_config::fmt::{HexUnderscore, MultilineFuncHeaderStyle, SingleLineBlockStyle};
 use itertools::{Either, Itertools};
 use solang_parser::pt::ImportPath;
 use std::{fmt::Write, str::FromStr};
@@ -1304,7 +1304,7 @@ impl<'a, W: Write> Formatter<'a, W> {
         let config = self.config.number_underscore;
 
         // get source if we preserve underscores
-        let (value, fractional, exponent) = if matches!(config, NumberUnderscore::Preserve) {
+        let (value, fractional, exponent) = if config.is_preserve() {
             let source = &self.source[loc.start()..loc.end()];
             // Strip unit
             let (source, _) = source.split_once(' ').unwrap_or((source, ""));
@@ -1336,7 +1336,7 @@ impl<'a, W: Write> Formatter<'a, W> {
         exp = exp.trim().trim_start_matches('0');
 
         let add_underscores = |string: &str, reversed: bool| -> String {
-            if !matches!(config, NumberUnderscore::Thousands) || string.len() < 5 {
+            if !config.is_thousands() || string.len() < 5 {
                 return string.to_string()
             }
             if reversed {
@@ -1377,6 +1377,32 @@ impl<'a, W: Write> Formatter<'a, W> {
         self.write_unit(unit)
     }
 
+    /// Write and hex literals according to the configuration.
+    fn write_hex_literal(&mut self, lit: &HexLiteral) -> Result<()> {
+        let HexLiteral { loc, hex } = lit;
+        match self.config.hex_underscore {
+            HexUnderscore::Remove => self.write_quoted_str(*loc, Some("hex"), hex),
+            HexUnderscore::Preserve => {
+                let quote = &self.source[loc.start()..loc.end()].trim_start_matches("hex");
+                // source is always quoted so we remove the quotes first so we can adhere to the
+                // configured quoting style
+                let hex = &quote[1..quote.len() - 1];
+                self.write_quoted_str(*loc, Some("hex"), hex)
+            }
+            HexUnderscore::Bytes => {
+                // split all bytes
+                let hex = hex
+                    .chars()
+                    .chunks(2)
+                    .into_iter()
+                    .map(|chunk| chunk.collect::<String>())
+                    .collect::<Vec<_>>()
+                    .join("_");
+                self.write_quoted_str(*loc, Some("hex"), &hex)
+            }
+        }
+    }
+
     /// Write built-in unit.
     fn write_unit(&mut self, unit: &mut Option<Identifier>) -> Result<()> {
         if let Some(unit) = unit {
@@ -2061,8 +2087,8 @@ impl<'a, W: Write> Visitor for Formatter<'a, W> {
                 }
             }
             Expression::HexLiteral(vals) => {
-                for HexLiteral { loc, hex } in vals {
-                    self.write_quoted_str(*loc, Some("hex"), hex)?;
+                for val in vals {
+                    self.write_hex_literal(val)?;
                 }
             }
             Expression::AddressLiteral(loc, val) => {

crates/fmt/testdata/HexUnderscore/bytes.fmt.sol

@@ -0,0 +1,10 @@
+// config: hex_underscore = "bytes"
+contract HexLiteral {
+    function test() external {
+        hex"01_23_00_00";
+        hex"01_23_00_00";
+        hex"01_23_00_00";
+        hex"";
+        hex"60_01_60_02_53";
+    }
+}

crates/fmt/testdata/HexUnderscore/fmt.sol

@@ -0,0 +1,9 @@
+contract HexLiteral {
+    function test() external {
+        hex"0123_0000";
+        hex"01230000";
+        hex"0123_00_00";
+        hex"";
+        hex"6001_6002_53";
+    }
+}

crates/fmt/testdata/HexUnderscore/original.sol

@@ -0,0 +1,9 @@
+contract HexLiteral {
+    function test() external {
+       hex"0123_0000";
+       hex"01230000";
+       hex"0123_00_00";
+       hex"";
+       hex"6001_6002_53";
+    }
+}

crates/fmt/testdata/HexUnderscore/preserve.fmt.sol

@@ -0,0 +1,10 @@
+// config: hex_underscore = "preserve"
+contract HexLiteral {
+    function test() external {
+        hex"0123_0000";
+        hex"01230000";
+        hex"0123_00_00";
+        hex"";
+        hex"6001_6002_53";
+    }
+}

crates/fmt/testdata/HexUnderscore/remove.fmt.sol

@@ -0,0 +1,10 @@
+// config: hex_underscore = "remove"
+contract HexLiteral {
+    function test() external {
+        hex"01230000";
+        hex"01230000";
+        hex"01230000";
+        hex"";
+        hex"6001600253";
+    }
+}

crates/fmt/testdata/NumberLiteralUnderscore/preserve.fmt.sol

@@ -0,0 +1,26 @@
+// config: number_underscore = "preserve"
+contract NumberLiteral {
+    function test() external {
+        1;
+        123_000;
+        1_2e345_678;
+        -1;
+        2e-10;
+        0.1;
+        1.3;
+        2.5e1;
+        1.23454;
+        1.2e34_5_678;
+        134411.2e34_5_678;
+        13431.134112e34_135_678;
+        13431.0134112;
+        13431.134112e-139_3141340;
+        134411.2e34_5_6780;
+        13431.134112e34_135_6780;
+        0.134112;
+        1.0;
+        13431.134112e-139_3141340;
+        123e456;
+        1_000;
+    }
+}

crates/fmt/tests/formatter.rs

@@ -193,6 +193,7 @@ test_directories! {
     IntTypes,
     InlineDisable,
     NumberLiteralUnderscore,
+    HexUnderscore,
     FunctionCall,
     TrailingComma,
     PragmaDirective,