1 files changed, 82 insertions, 0 deletions
diff --git a/openpgp/src/types/compression_level.rs b/openpgp/src/types/compression_level.rs
new file mode 100644
index 00000000..7ac32d31
--- /dev/null
+++ b/openpgp/src/types/compression_level.rs
@@ -0,0 +1,82 @@
+//! Common code for the compression writers.
+
+use crate::{
+    Error,
+    Result,
+};
+
+/// Compression level.
+///
+/// This value is used by the encoders to tune their compression
+/// strategy.  The level is restricted to levels commonly used by
+/// compression libraries, `0` to `9`, where `0` means no compression,
+/// `1` means fastest compression, `6` being a good default, and
+/// meaning `9` best compression.
+#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct CompressionLevel(u8);
+
+impl Default for CompressionLevel {
+    fn default() -> Self {
+        Self(6)
+    }
+}
+
+impl CompressionLevel {
+    /// Creates a new compression level.
+    ///
+    /// `level` must be in range `0..10`, where `0` means no
+    /// compression, `1` means fastest compression, `6` being a good
+    /// default, and meaning `9` best compression.
+    pub fn new(level: u8) -> Result<CompressionLevel> {
+        if level < 10 {
+            Ok(Self(level))
+        } else {
+            Err(Error::InvalidArgument(
+                format!("compression level out of range: {}", level)).into())
+        }
+    }
+
+    /// No compression.
+    pub fn none() -> CompressionLevel {
+        Self(0)
+    }
+
+    /// Fastest compression.
+    pub fn fastest() -> CompressionLevel {
+        Self(1)
+    }
+    /// Best compression.
+    pub fn best() -> CompressionLevel {
+        Self(9)
+    }
+}
+
+#[cfg(feature = "compression-deflate")]
+mod into_deflate_compression {
+    use flate2::Compression;
+    use super::*;
+
+    impl From<CompressionLevel> for Compression {
+        fn from(l: CompressionLevel) -> Self {
+            Compression::new(l.0 as u32)
+        }
+    }
+}
+
+#[cfg(feature = "compression-bzip2")]
+mod into_bzip2_compression {
+    use bzip2::Compression;
+    use super::*;
+
+    impl From<CompressionLevel> for Compression {
+        fn from(l: CompressionLevel) -> Self {
+            if l <= CompressionLevel::fastest() {
+                Compression::Fastest
+            } else if l <= CompressionLevel::default() {
+                Compression::Default
+            } else {
+                Compression::Best
+            }
+        }
+    }
+}