feat(writer): Implement TomlInteger

crates/toml_writer/src/integer.rs

@@ -0,0 +1,194 @@
+use core::fmt::{self, Display};
+
+/// Describes how a TOML integer should be formatted.
+#[derive(Copy, Clone, Debug)]
+pub struct TomlIntegerFormat {
+    radix: Radix,
+}
+
+impl TomlIntegerFormat {
+    /// Creates a new integer format (decimal).
+    pub fn new() -> Self {
+        Self {
+            radix: Radix::Decimal,
+        }
+    }
+
+    /// Sets the format to decimal.
+    pub fn as_decimal(mut self) -> Self {
+        self.radix = Radix::Decimal;
+        self
+    }
+
+    /// Sets the format to hexadecimal with all characters in uppercase.
+    pub fn as_hex_upper(mut self) -> Self {
+        self.radix = Radix::Hexadecimal {
+            case: HexCase::Upper,
+        };
+        self
+    }
+
+    /// Sets the format to hexadecimal with all characters in lowercase.
+    pub fn as_hex_lower(mut self) -> Self {
+        self.radix = Radix::Hexadecimal {
+            case: HexCase::Lower,
+        };
+        self
+    }
+
+    /// Sets the format to octal.
+    pub fn as_octal(mut self) -> Self {
+        self.radix = Radix::Octal;
+        self
+    }
+
+    /// Sets the format to binary.
+    pub fn as_binary(mut self) -> Self {
+        self.radix = Radix::Binary;
+        self
+    }
+
+    /// Formats `value` as a TOML integer.
+    ///
+    /// Returns `None` if the value cannot be formatted
+    /// (e.g. value is negative and the radix is not decimal).
+    pub fn format<N: PartialOrd<i32>>(self, value: N) -> Option<TomlInteger<N>>
+    where
+        TomlInteger<N>: crate::WriteTomlValue,
+    {
+        match self.radix {
+            Radix::Decimal => (),
+            Radix::Hexadecimal { .. } | Radix::Octal | Radix::Binary => {
+                if value < 0 {
+                    return None;
+                }
+            }
+        }
+
+        Some(TomlInteger {
+            value,
+            format: self,
+        })
+    }
+}
+
+impl Default for TomlIntegerFormat {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+/// Helper struct for formatting TOML integers.
+///
+/// This may be constructed by calling [`TomlIntegerFormat::format()`].
+#[derive(Copy, Clone, Debug)]
+pub struct TomlInteger<N> {
+    value: N,
+    format: TomlIntegerFormat,
+}
+
+impl crate::WriteTomlValue for TomlInteger<u8> {
+    fn write_toml_value<W: crate::TomlWrite + ?Sized>(&self, writer: &mut W) -> fmt::Result {
+        write_toml_value(self.value, &self.format, writer)
+    }
+}
+
+impl crate::WriteTomlValue for TomlInteger<i8> {
+    fn write_toml_value<W: crate::TomlWrite + ?Sized>(&self, writer: &mut W) -> fmt::Result {
+        write_toml_value(self.value, &self.format, writer)
+    }
+}
+
+impl crate::WriteTomlValue for TomlInteger<u16> {
+    fn write_toml_value<W: crate::TomlWrite + ?Sized>(&self, writer: &mut W) -> fmt::Result {
+        write_toml_value(self.value, &self.format, writer)
+    }
+}
+
+impl crate::WriteTomlValue for TomlInteger<i16> {
+    fn write_toml_value<W: crate::TomlWrite + ?Sized>(&self, writer: &mut W) -> fmt::Result {
+        write_toml_value(self.value, &self.format, writer)
+    }
+}
+
+impl crate::WriteTomlValue for TomlInteger<u32> {
+    fn write_toml_value<W: crate::TomlWrite + ?Sized>(&self, writer: &mut W) -> fmt::Result {
+        write_toml_value(self.value, &self.format, writer)
+    }
+}
+
+impl crate::WriteTomlValue for TomlInteger<i32> {
+    fn write_toml_value<W: crate::TomlWrite + ?Sized>(&self, writer: &mut W) -> fmt::Result {
+        write_toml_value(self.value, &self.format, writer)
+    }
+}
+
+impl crate::WriteTomlValue for TomlInteger<u64> {
+    fn write_toml_value<W: crate::TomlWrite + ?Sized>(&self, writer: &mut W) -> fmt::Result {
+        write_toml_value(self.value, &self.format, writer)
+    }
+}
+
+impl crate::WriteTomlValue for TomlInteger<i64> {
+    fn write_toml_value<W: crate::TomlWrite + ?Sized>(&self, writer: &mut W) -> fmt::Result {
+        write_toml_value(self.value, &self.format, writer)
+    }
+}
+
+impl crate::WriteTomlValue for TomlInteger<u128> {
+    fn write_toml_value<W: crate::TomlWrite + ?Sized>(&self, writer: &mut W) -> fmt::Result {
+        write_toml_value(self.value, &self.format, writer)
+    }
+}
+
+impl crate::WriteTomlValue for TomlInteger<i128> {
+    fn write_toml_value<W: crate::TomlWrite + ?Sized>(&self, writer: &mut W) -> fmt::Result {
+        write_toml_value(self.value, &self.format, writer)
+    }
+}
+
+impl crate::WriteTomlValue for TomlInteger<usize> {
+    fn write_toml_value<W: crate::TomlWrite + ?Sized>(&self, writer: &mut W) -> fmt::Result {
+        write_toml_value(self.value, &self.format, writer)
+    }
+}
+
+impl crate::WriteTomlValue for TomlInteger<isize> {
+    fn write_toml_value<W: crate::TomlWrite + ?Sized>(&self, writer: &mut W) -> fmt::Result {
+        write_toml_value(self.value, &self.format, writer)
+    }
+}
+
+#[derive(Copy, Clone, Debug)]
+enum Radix {
+    Decimal,
+    Hexadecimal { case: HexCase },
+    Octal,
+    Binary,
+}
+
+#[derive(Copy, Clone, Debug)]
+enum HexCase {
+    Upper,
+    Lower,
+}
+
+fn write_toml_value<
+    N: Display + fmt::UpperHex + fmt::LowerHex + fmt::Octal + fmt::Binary,
+    W: crate::TomlWrite + ?Sized,
+>(
+    value: N,
+    format: &TomlIntegerFormat,
+    writer: &mut W,
+) -> fmt::Result {
+    match format.radix {
+        Radix::Decimal => write!(writer, "{value}")?,
+        Radix::Hexadecimal { case } => match case {
+            HexCase::Upper => write!(writer, "0x{value:X}")?,
+            HexCase::Lower => write!(writer, "0x{value:x}")?,
+        },
+        Radix::Octal => write!(writer, "0o{value:o}")?,
+        Radix::Binary => write!(writer, "0b{value:b}")?,
+    }
+    Ok(())
+}

crates/toml_writer/src/lib.rs

@@ -59,11 +59,14 @@
 #[cfg(feature = "alloc")]
 extern crate alloc;
 
+mod integer;
 mod key;
 mod string;
 mod value;
 mod write;
 
+pub use integer::TomlInteger;
+pub use integer::TomlIntegerFormat;
 #[cfg(feature = "alloc")]
 pub use key::ToTomlKey;
 pub use key::WriteTomlKey;

crates/toml_writer/tests/integer.rs

@@ -0,0 +1,99 @@
+#![cfg(feature = "alloc")]
+
+use snapbox::prelude::*;
+use snapbox::str;
+
+use toml_writer::ToTomlValue;
+use toml_writer::TomlInteger;
+use toml_writer::TomlIntegerFormat;
+use toml_writer::WriteTomlValue;
+
+#[track_caller]
+fn t<N: Copy + core::fmt::Debug + PartialOrd<i32>>(value: N, expected: impl IntoData)
+where
+    TomlInteger<N>: WriteTomlValue,
+{
+    let results = IntegerResults {
+        value,
+        decimal: TomlIntegerFormat::new()
+            .as_decimal()
+            .format(value)
+            .map(|i| i.to_toml_value()),
+        hex_upper: TomlIntegerFormat::new()
+            .as_hex_upper()
+            .format(value)
+            .map(|i| i.to_toml_value()),
+        hex_lower: TomlIntegerFormat::new()
+            .as_hex_lower()
+            .format(value)
+            .map(|i| i.to_toml_value()),
+        octal: TomlIntegerFormat::new()
+            .as_octal()
+            .format(value)
+            .map(|i| i.to_toml_value()),
+        binary: TomlIntegerFormat::new()
+            .as_binary()
+            .format(value)
+            .map(|i| i.to_toml_value()),
+    };
+    snapbox::assert_data_eq!(results.to_debug(), expected.raw());
+}
+
+#[derive(Debug)]
+#[allow(dead_code)]
+struct IntegerResults<N: core::fmt::Debug> {
+    value: N,
+    decimal: Option<String>,
+    hex_upper: Option<String>,
+    hex_lower: Option<String>,
+    octal: Option<String>,
+    binary: Option<String>,
+}
+
+#[test]
+fn positive() {
+    t(
+        42,
+        str![[r#"
+IntegerResults {
+    value: 42,
+    decimal: Some(
+        "42",
+    ),
+    hex_upper: Some(
+        "0x2A",
+    ),
+    hex_lower: Some(
+        "0x2a",
+    ),
+    octal: Some(
+        "0o52",
+    ),
+    binary: Some(
+        "0b101010",
+    ),
+}
+
+"#]],
+    );
+}
+
+#[test]
+fn negative() {
+    t(
+        -42,
+        str![[r#"
+IntegerResults {
+    value: -42,
+    decimal: Some(
+        "-42",
+    ),
+    hex_upper: None,
+    hex_lower: None,
+    octal: None,
+    binary: None,
+}
+
+"#]],
+    );
+}