Make functions const where possible

src/aes.rs

@@ -45,7 +45,7 @@ pub struct AesReader<R> {
 }
 
 impl<R: Read> AesReader<R> {
-    pub fn new(reader: R, aes_mode: AesMode, compressed_size: u64) -> AesReader<R> {
+    pub const fn new(reader: R, aes_mode: AesMode, compressed_size: u64) -> AesReader<R> {
         let data_length = compressed_size
             - (PWD_VERIFY_LENGTH + AUTH_CODE_LENGTH + aes_mode.salt_length()) as u64;
 

src/compression.rs

@@ -100,7 +100,7 @@ impl CompressionMethod {
         since = "0.5.7",
         note = "use a constant to construct a compression method"
     )]
-    pub fn from_u16(val: u16) -> CompressionMethod {
+    pub const fn from_u16(val: u16) -> CompressionMethod {
         #[allow(deprecated)]
         match val {
             0 => CompressionMethod::Stored,
@@ -128,7 +128,7 @@ impl CompressionMethod {
         since = "0.5.7",
         note = "to match on other compression methods, use a constant"
     )]
-    pub fn to_u16(self) -> u16 {
+    pub const fn to_u16(self) -> u16 {
         #[allow(deprecated)]
         match self {
             CompressionMethod::Stored => 0,

src/read.rs

@@ -107,7 +107,7 @@ impl<'a> CryptoReader<'a> {
     }
 
     /// Returns `true` if the data is encrypted using AE2.
-    pub fn is_ae2_encrypted(&self) -> bool {
+    pub const fn is_ae2_encrypted(&self) -> bool {
         #[cfg(feature = "aes-crypto")]
         return matches!(
             self,
@@ -692,7 +692,7 @@ impl<R: Read + Seek> ZipArchive<R> {
     }
 }
 
-fn unsupported_zip_error<T>(detail: &'static str) -> ZipResult<T> {
+const fn unsupported_zip_error<T>(detail: &'static str) -> ZipResult<T> {
     Err(ZipError::UnsupportedArchive(detail))
 }
 

src/read/stream.rs

@@ -15,7 +15,7 @@ pub struct ZipStreamReader<R>(R);
 
 impl<R> ZipStreamReader<R> {
     /// Create a new ZipStreamReader
-    pub fn new(reader: R) -> Self {
+    pub const fn new(reader: R) -> Self {
         Self(reader)
     }
 }
@@ -204,7 +204,7 @@ impl ZipStreamFileMetadata {
     }
 
     /// Get unix mode for the file
-    pub fn unix_mode(&self) -> Option<u32> {
+    pub const fn unix_mode(&self) -> Option<u32> {
         self.0.unix_mode()
     }
 }

src/types.rs

@@ -63,7 +63,7 @@ pub enum System {
 }
 
 impl System {
-    pub fn from_u8(system: u8) -> System {
+    pub const fn from_u8(system: u8) -> System {
         use self::System::*;
 
         match system {
@@ -161,7 +161,7 @@ impl Default for DateTime {
 
 impl DateTime {
     /// Converts an msdos (u16, u16) pair to a DateTime object
-    pub fn from_msdos(datepart: u16, timepart: u16) -> DateTime {
+    pub const fn from_msdos(datepart: u16, timepart: u16) -> DateTime {
         let seconds = (timepart & 0b0000000000011111) << 1;
         let minutes = (timepart & 0b0000011111100000) >> 5;
         let hours = (timepart & 0b1111100000000000) >> 11;
@@ -239,12 +239,12 @@ impl DateTime {
     }
 
     /// Gets the time portion of this datetime in the msdos representation
-    pub fn timepart(&self) -> u16 {
+    pub const fn timepart(&self) -> u16 {
         ((self.second as u16) >> 1) | ((self.minute as u16) << 5) | ((self.hour as u16) << 11)
     }
 
     /// Gets the date portion of this datetime in the msdos representation
-    pub fn datepart(&self) -> u16 {
+    pub const fn datepart(&self) -> u16 {
         (self.day as u16) | ((self.month as u16) << 5) | ((self.year - 1980) << 9)
     }
 
@@ -258,7 +258,7 @@ impl DateTime {
     }
 
     /// Get the year. There is no epoch, i.e. 2018 will be returned as 2018.
-    pub fn year(&self) -> u16 {
+    pub const fn year(&self) -> u16 {
         self.year
     }
 
@@ -267,7 +267,7 @@ impl DateTime {
     /// # Warning
     ///
     /// When read from a zip file, this may not be a reasonable value
-    pub fn month(&self) -> u8 {
+    pub const fn month(&self) -> u8 {
         self.month
     }
 
@@ -276,7 +276,7 @@ impl DateTime {
     /// # Warning
     ///
     /// When read from a zip file, this may not be a reasonable value
-    pub fn day(&self) -> u8 {
+    pub const fn day(&self) -> u8 {
         self.day
     }
 
@@ -285,7 +285,7 @@ impl DateTime {
     /// # Warning
     ///
     /// When read from a zip file, this may not be a reasonable value
-    pub fn hour(&self) -> u8 {
+    pub const fn hour(&self) -> u8 {
         self.hour
     }
 
@@ -294,7 +294,7 @@ impl DateTime {
     /// # Warning
     ///
     /// When read from a zip file, this may not be a reasonable value
-    pub fn minute(&self) -> u8 {
+    pub const fn minute(&self) -> u8 {
         self.minute
     }
 
@@ -303,7 +303,7 @@ impl DateTime {
     /// # Warning
     ///
     /// When read from a zip file, this may not be a reasonable value
-    pub fn second(&self) -> u8 {
+    pub const fn second(&self) -> u8 {
         self.second
     }
 }
@@ -338,7 +338,7 @@ pub const DEFAULT_VERSION: u8 = 46;
 pub struct AtomicU64(atomic::AtomicU64);
 
 impl AtomicU64 {
-    pub fn new(v: u64) -> Self {
+    pub const fn new(v: u64) -> Self {
         Self(atomic::AtomicU64::new(v))
     }
 
@@ -456,7 +456,7 @@ impl ZipFileData {
     }
 
     /// Get unix mode for the file
-    pub(crate) fn unix_mode(&self) -> Option<u32> {
+    pub(crate) const fn unix_mode(&self) -> Option<u32> {
         if self.external_attributes == 0 {
             return None;
         }
@@ -480,13 +480,13 @@ impl ZipFileData {
         }
     }
 
-    pub fn zip64_extension(&self) -> bool {
+    pub const fn zip64_extension(&self) -> bool {
         self.uncompressed_size > 0xFFFFFFFF
             || self.compressed_size > 0xFFFFFFFF
             || self.header_start > 0xFFFFFFFF
     }
 
-    pub fn version_needed(&self) -> u16 {
+    pub const fn version_needed(&self) -> u16 {
         // higher versions matched first
         match (self.zip64_extension(), self.compression_method) {
             #[cfg(feature = "bzip2")]
@@ -517,11 +517,11 @@ pub enum AesMode {
 
 #[cfg(feature = "aes-crypto")]
 impl AesMode {
-    pub fn salt_length(&self) -> usize {
+    pub const fn salt_length(&self) -> usize {
         self.key_length() / 2
     }
 
-    pub fn key_length(&self) -> usize {
+    pub const fn key_length(&self) -> usize {
         match self {
             Self::Aes128 => 16,
             Self::Aes192 => 24,

src/write.rs

@@ -236,7 +236,7 @@ impl FileOptions {
     /// is enabled, `CompressionMethod::Zlib` is the default. If all else fails,
     /// `CompressionMethod::Stored` becomes the default and files are written uncompressed.
     #[must_use]
-    pub fn compression_method(mut self, method: CompressionMethod) -> FileOptions {
+    pub const fn compression_method(mut self, method: CompressionMethod) -> FileOptions {
         self.compression_method = method;
         self
     }
@@ -252,7 +252,7 @@ impl FileOptions {
     /// * `Zstd`: -7 - 22, with zero being mapped to default level. Default is 3
     /// * others: only `None` is allowed
     #[must_use]
-    pub fn compression_level(mut self, level: Option<i32>) -> FileOptions {
+    pub const fn compression_level(mut self, level: Option<i32>) -> FileOptions {
         self.compression_level = level;
         self
     }
@@ -262,7 +262,7 @@ impl FileOptions {
     /// The default is the current timestamp if the 'time' feature is enabled, and 1980-01-01
     /// otherwise
     #[must_use]
-    pub fn last_modified_time(mut self, mod_time: DateTime) -> FileOptions {
+    pub const fn last_modified_time(mut self, mod_time: DateTime) -> FileOptions {
         self.last_modified_time = mod_time;
         self
     }
@@ -277,7 +277,7 @@ impl FileOptions {
     /// higher file mode bits. So it cannot be used to denote an entry as a directory,
     /// symlink, or other special file type.
     #[must_use]
-    pub fn unix_permissions(mut self, mode: u32) -> FileOptions {
+    pub const fn unix_permissions(mut self, mode: u32) -> FileOptions {
         self.permissions = Some(mode & 0o777);
         self
     }
@@ -288,7 +288,7 @@ impl FileOptions {
     /// aborted. If set to `true`, readers will require ZIP64 support and if the file does not
     /// exceed the limit, 20 B are wasted. The default is `false`.
     #[must_use]
-    pub fn large_file(mut self, large: bool) -> FileOptions {
+    pub const fn large_file(mut self, large: bool) -> FileOptions {
         self.large_file = large;
         self
     }
@@ -346,7 +346,7 @@ impl FileOptions {
 
     /// Sets the alignment to the given number of bytes.
     #[must_use]
-    pub fn with_alignment(mut self, alignment: u16) -> FileOptions {
+    pub const fn with_alignment(mut self, alignment: u16) -> FileOptions {
         self.alignment = alignment;
         self
     }
@@ -357,13 +357,13 @@ impl FileOptions {
     /// are larger than about 32 KiB.
     #[must_use]
     #[cfg(feature = "deflate-zopfli")]
-    pub fn with_zopfli_buffer(mut self, size: Option<usize>) -> FileOptions {
+    pub const fn with_zopfli_buffer(mut self, size: Option<usize>) -> FileOptions {
         self.zopfli_buffer_size = size;
         self
     }
 
     /// Returns the compression level currently set.
-    pub fn get_compression_level(&self) -> Option<i32> {
+    pub const fn get_compression_level(&self) -> Option<i32> {
         self.compression_level
     }
 }
@@ -581,7 +581,7 @@ impl<W: Write + Seek> ZipWriter<W> {
     }
 
     /// Returns true if a file is currently open for writing.
-    pub fn is_writing_file(&self) -> bool {
+    pub const fn is_writing_file(&self) -> bool {
         self.writing_to_file && !self.inner.is_closed()
     }
 
@@ -610,7 +610,7 @@ impl<W: Write + Seek> ZipWriter<W> {
     ///
     /// This returns the raw bytes of the comment. The comment
     /// is typically expected to be encoded in UTF-8
-    pub fn get_raw_comment(&self) -> &Vec<u8> {
+    pub const fn get_raw_comment(&self) -> &Vec<u8> {
         &self.comment
     }
 
@@ -1364,7 +1364,7 @@ impl<W: Write + Seek> GenericZipWriter<W> {
         }
     }
 
-    fn is_closed(&self) -> bool {
+    const fn is_closed(&self) -> bool {
         matches!(*self, GenericZipWriter::Closed)
     }
 

src/zipcrypto.rs

@@ -36,7 +36,7 @@ impl Debug for ZipCryptoKeys {
 }
 
 impl ZipCryptoKeys {
-    fn new() -> ZipCryptoKeys {
+    const fn new() -> ZipCryptoKeys {
         ZipCryptoKeys {
             key_0: Wrapping(0x12345678),
             key_1: Wrapping(0x23456789),