From 800957576505f3a8c12ef5106d40819d24148009 Mon Sep 17 00:00:00 2001
From: Nathan Fisher <nfisher.sr@gmail.com>
Date: Fri, 5 Jan 2024 19:05:34 -0500
Subject: [PATCH] Add `SemVer` struct and related impl's

---
 src/error.rs  | 13 +++++++-
 src/lib.rs    |  5 ++-
 src/semver.rs | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 103 insertions(+), 2 deletions(-)

diff --git a/src/error.rs b/src/error.rs
index 793738f..fd08412 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -1,8 +1,13 @@
-use std::{fmt, num::TryFromIntError};
+use std::{
+    fmt,
+    num::{ParseIntError, TryFromIntError},
+};
 
 #[derive(Debug, PartialEq)]
 pub enum Error {
     FromUint,
+    Range,
+    ParseInt,
     ParsePreRelease,
     ParseSemver,
     TryFromInt,
@@ -21,3 +26,9 @@ impl From<TryFromIntError> for Error {
         Self::TryFromInt
     }
 }
+
+impl From<ParseIntError> for Error {
+    fn from(_value: ParseIntError) -> Self {
+        Self::ParseInt
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 6ff5fc2..7069b1e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,7 @@
 mod error;
 mod prerelease;
+mod semver;
 
-pub use {error::Error, prerelease::PreRelease};
+pub use {error::Error, prerelease::PreRelease, semver::SemVer};
+
+pub static MAX_U12: u16 = 4096;
diff --git a/src/semver.rs b/src/semver.rs
index e69de29..c39809f 100644
--- a/src/semver.rs
+++ b/src/semver.rs
@@ -0,0 +1,87 @@
+use {
+    crate::{Error, PreRelease, MAX_U12},
+    serde::{Deserialize, Serialize},
+    std::{cmp::Ordering, fmt, str::FromStr},
+};
+
+#[derive(Clone, Copy, Debug, Deserialize, Serialize)]
+pub struct SemVer {
+    pub major: u16,
+    pub minor: u16,
+    pub patch: u16,
+    pub pre: PreRelease,
+}
+
+impl fmt::Display for SemVer {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}.{}.{}", self.major, self.minor, self.patch)?;
+        match self.pre {
+            PreRelease::None => Ok(()),
+            p => write!(f, "_{p}"),
+        }
+    }
+}
+
+impl FromStr for SemVer {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let (s, pre) = match s.split_once('_') {
+            Some((a, b)) => (a, b.parse::<PreRelease>()?),
+            None => (s, PreRelease::None),
+        };
+        let split = s.split('.').collect::<Vec<_>>();
+        match split.len() {
+            3 => {
+                let major = split.first().unwrap().parse::<u16>()?;
+                let minor = split.get(1).unwrap().parse::<u16>()?;
+                let patch = split.get(2).unwrap().parse::<u16>()?;
+                if major > MAX_U12 || minor > MAX_U12 || patch > MAX_U12 {
+                    return Err(Error::Range);
+                }
+                Ok(Self {
+                    major,
+                    minor,
+                    patch,
+                    pre,
+                })
+            }
+            _ => Err(Error::ParseSemver),
+        }
+    }
+}
+
+impl From<SemVer> for u64 {
+    fn from(value: SemVer) -> Self {
+        let major = u64::from(value.major) << 52;
+        let minor = u64::from(value.minor) << 40;
+        let patch = u64::from(value.patch) << 28;
+        let pre = u64::from(u16::from(value.pre));
+        major | minor | patch | pre
+    }
+}
+
+impl PartialEq for SemVer {
+    fn eq(&self, other: &Self) -> bool {
+        self.major == other.major
+            && self.minor == other.minor
+            && self.patch == other.patch
+            && self.pre == other.pre
+    }
+}
+
+impl Eq for SemVer {}
+
+impl Ord for SemVer {
+    fn cmp(&self, other: &Self) -> Ordering {
+        let a = u64::from(*self);
+        let b = u64::from(*other);
+        a.cmp(&b)
+    }
+}
+
+impl PartialOrd for SemVer {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}