feat: provide constants for compression methods

src/compression.rs

@@ -10,7 +10,7 @@ use std::fmt;
 ///
 /// When creating ZIP files, you may choose the method to use with
 /// [`zip::write::FileOptions::compression_method`]
-#[derive(Copy, Clone, PartialEq, Debug)]
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub enum CompressionMethod {
     /// Store the file as is
     Stored,
@@ -25,18 +25,53 @@ pub enum CompressionMethod {
     #[cfg(feature = "bzip2")]
     Bzip2,
     /// Unsupported compression method
-    #[deprecated(
+    #[deprecated(since = "0.5.7", note = "use the constants instead")]
-        since = "0.5.7",
-        note = "implementation details are being removed from the public API"
-    )]
     Unsupported(u16),
 }
-
+#[allow(deprecated, missing_docs)]
+/// All compression methods defined for the ZIP format
+impl CompressionMethod {
+    pub const STORE: Self = Self::Stored;
+    pub const SHRINK: Self = Self::Unsupported(1);
+    pub const REDUCE_1: Self = Self::Unsupported(2);
+    pub const REDUCE_2: Self = Self::Unsupported(3);
+    pub const REDUCE_3: Self = Self::Unsupported(4);
+    pub const REDUCE_4: Self = Self::Unsupported(5);
+    pub const IMPLODE: Self = Self::Unsupported(6);
+    #[cfg(any(
+        feature = "deflate",
+        feature = "deflate-miniz",
+        feature = "deflate-zlib"
+    ))]
+    pub const DEFLATE: Self = Self::Deflated;
+    #[cfg(not(any(
+        feature = "deflate",
+        feature = "deflate-miniz",
+        feature = "deflate-zlib"
+    )))]
+    pub const DEFLATE: Self = Self::Unsupported(8);
+    pub const DEFLATE64: Self = Self::Unsupported(9);
+    pub const PKWARE_IMPLODE: Self = Self::Unsupported(10);
+    #[cfg(feature = "bzip2")]
+    pub const BZIP2: Self = Self::Bzip2;
+    #[cfg(not(feature = "bzip2"))]
+    pub const BZIP2: Self = Self::Unsupported(12);
+    pub const LZMA: Self = Self::Unsupported(14);
+    pub const IBM_ZOS_CMPSC: Self = Self::Unsupported(16);
+    pub const IBM_TERSE: Self = Self::Unsupported(18);
+    pub const ZSTD_DEPRECATED: Self = Self::Unsupported(20);
+    pub const ZSTD: Self = Self::Unsupported(93);
+    pub const MP3: Self = Self::Unsupported(94);
+    pub const XZ: Self = Self::Unsupported(95);
+    pub const JPEG: Self = Self::Unsupported(96);
+    pub const WAVPACK: Self = Self::Unsupported(97);
+    pub const PPMD: Self = Self::Unsupported(98);
+}
 impl CompressionMethod {
     /// Converts an u16 to its corresponding CompressionMethod
     #[deprecated(
         since = "0.5.7",
-        note = "implementation details are being removed from the public API"
+        note = "use a constant to construct a compression method"
     )]
     pub fn from_u16(val: u16) -> CompressionMethod {
         #[allow(deprecated)]
@@ -58,7 +93,7 @@ impl CompressionMethod {
     /// Converts a CompressionMethod to a u16
     #[deprecated(
         since = "0.5.7",
-        note = "implementation details are being removed from the public API"
+        note = "to match on other compression methods, use a constant"
     )]
     pub fn to_u16(self) -> u16 {
         #[allow(deprecated)]