Replace FromPrimitive with our own tag macro

Cargo.toml

@@ -19,8 +19,6 @@ exclude = ["tests/images/*", "tests/fuzz_images/*"]
 [dependencies]
 byteorder = "1.2"
 lzw = "0.10"
-num-derive = "0.3"
-num-traits = "0.2"
 miniz_oxide = "0.3"
 
 [dev-dependencies]

src/decoder/ifd.rs

@@ -10,27 +10,42 @@ use {TiffError, TiffFormatError, TiffResult, TiffUnsupportedError};
 use self::Value::{Ascii, List, Rational, Unsigned, Signed, SRational};
 
 macro_rules! tags {
-    {$(
-        $tag:ident
-        $val:expr;
-    )*} => {
-
-        /// TIFF tag
+    {
+        // Permit arbitrary meta items, which include documentation.
+        $( #[$enum_attr:meta] )*
+        $vis:vis enum $name:ident($ty:ty) $(unknown($unknown_doc:literal))* {
+            // Each of the `Name = Val,` permitting documentation.
+            $($(#[$ident_attr:meta])* $tag:ident = $val:expr,)*
+        }
+    } => {
+        $( #[$enum_attr] )*
         #[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
-        pub enum Tag {
-            $($tag,)*
-            Unknown(u16)
+        pub enum $name {
+            $($(#[$ident_attr])* $tag,)*
+            // FIXME: switch to non_exhaustive once stabilized and compiler requirement new enough
+            #[doc(hidden)]
+            __NonExhaustive,
+            $( 
+                #[doc = $unknown_doc]
+                Unknown($ty),
+            )*
         }
-        impl Tag {
-            pub fn from_u16(n: u16) -> Tag {
-                $(if n == $val { Tag::$tag } else)* {
-                    Tag::Unknown(n)
+
+        impl $name {
+            #[inline(always)]
+            fn __from_inner_type(n: $ty) -> Result<Self, $ty> {
+                match n {
+                    $( $val => Ok($name::$tag), )*
+                    n => Err(n),
                 }
             }
-            pub fn to_u16(&self) -> u16 {
+
+            #[inline(always)]
+            fn __to_inner_type(&self) -> $ty {
                 match *self {
-                    $( Tag::$tag => $val, )*
-                    Tag::Unknown(n) => n,
+                    $( $name::$tag => $val, )*
+                    $( $name::Unknown(n) => { $unknown_doc; n }, )*
+                    $name::__NonExhaustive => unreachable!(),
                 }
             }
         }
@@ -39,51 +54,65 @@ macro_rules! tags {
 
 // Note: These tags appear in the order they are mentioned in the TIFF reference
 tags! {
+/// TIFF tags
+pub enum Tag(u16) unknown("A private or extension tag") {
     // Baseline tags:
-    Artist 315;
+    Artist = 315,
     // grayscale images PhotometricInterpretation 1 or 3
-    BitsPerSample 258;
-    CellLength 265; // TODO add support
-    CellWidth 264; // TODO add support
+    BitsPerSample = 258,
+    CellLength = 265, // TODO add support
+    CellWidth = 264, // TODO add support
     // palette-color images (PhotometricInterpretation 3)
-    ColorMap 320; // TODO add support
-    Compression 259; // TODO add support for 2 and 32773
-    Copyright 33_432;
-    DateTime 306;
-    ExtraSamples 338; // TODO add support
-    FillOrder 266; // TODO add support
-    FreeByteCounts 289; // TODO add support
-    FreeOffsets 288; // TODO add support
-    GrayResponseCurve 291; // TODO add support
-    GrayResponseUnit 290; // TODO add support
-    HostComputer 316;
-    ImageDescription 270;
-    ImageLength 257;
-    ImageWidth 256;
-    Make 271;
-    MaxSampleValue 281; // TODO add support
-    MinSampleValue 280; // TODO add support
-    Model 272;
-    NewSubfileType 254; // TODO add support
-    Orientation 274; // TODO add support
-    PhotometricInterpretation 262;
-    PlanarConfiguration 284;
-    ResolutionUnit 296; // TODO add support
-    RowsPerStrip 278;
-    SamplesPerPixel 277;
-    Software 305;
-    StripByteCounts 279;
-    StripOffsets 273;
-    SubfileType 255; // TODO add support
-    Threshholding 263; // TODO add support
-    XResolution 282;
-    YResolution 283;
+    ColorMap = 320, // TODO add support
+    Compression = 259, // TODO add support for 2 and 32773
+    Copyright = 33_432,
+    DateTime = 306,
+    ExtraSamples = 338, // TODO add support
+    FillOrder = 266, // TODO add support
+    FreeByteCounts = 289, // TODO add support
+    FreeOffsets = 288, // TODO add support
+    GrayResponseCurve = 291, // TODO add support
+    GrayResponseUnit = 290, // TODO add support
+    HostComputer = 316,
+    ImageDescription = 270,
+    ImageLength = 257,
+    ImageWidth = 256,
+    Make = 271,
+    MaxSampleValue = 281, // TODO add support
+    MinSampleValue = 280, // TODO add support
+    Model = 272,
+    NewSubfileType = 254, // TODO add support
+    Orientation = 274, // TODO add support
+    PhotometricInterpretation = 262,
+    PlanarConfiguration = 284,
+    ResolutionUnit = 296, // TODO add support
+    RowsPerStrip = 278,
+    SamplesPerPixel = 277,
+    Software = 305,
+    StripByteCounts = 279,
+    StripOffsets = 273,
+    SubfileType = 255, // TODO add support
+    Threshholding = 263, // TODO add support
+    XResolution = 282,
+    YResolution = 283,
     // Advanced tags
-    Predictor 317;
+    Predictor = 317,
 }
+}
+
+impl Tag {
+    pub fn from_u16(val: u16) -> Self {
+        Self::__from_inner_type(val).unwrap_or_else(Tag::Unknown)
+    }
 
-#[derive(Clone, Copy, Debug, FromPrimitive)]
-pub enum Type {
+    pub fn to_u16(&self) -> u16 {
+        Self::__to_inner_type(self)
+    }
+}
+
+tags! {
+/// The type of an IFD entry (a 2 byte field).
+pub enum Type(u16) {
     BYTE = 1,
     ASCII = 2,
     SHORT = 3,
@@ -94,6 +123,18 @@ pub enum Type {
     SLONG = 9,
     SRATIONAL = 10,
 }
+}
+
+impl Type {
+    pub fn from_u16(val: u16) -> Option<Self> {
+        Self::__from_inner_type(val).ok()
+    }
+
+    pub fn to_u16(&self) -> u16 {
+        Self::__to_inner_type(self)
+    }
+}
+
 
 #[allow(unused_qualifications)]
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
@@ -104,6 +145,8 @@ pub enum Value {
     Rational(u32, u32),
     SRational(i32, i32),
     Ascii(String),
+    #[doc(hidden)] // Do not match against this.
+    __NonExhaustive,
 }
 
 impl Value {

src/decoder/mod.rs

@@ -1,4 +1,3 @@
-use num_traits::{FromPrimitive, Num};
 use std::collections::HashMap;
 use std::io::{self, Read, Seek};
 use std::cmp;
@@ -9,6 +8,7 @@ use self::ifd::Directory;
 
 use self::stream::{ByteOrder, EndianReader, LZWReader, DeflateReader, PackBitsReader, SmartReader};
 
+#[macro_use]
 pub mod ifd;
 mod stream;
 
@@ -80,8 +80,8 @@ impl<'a> DecodingBuffer<'a> {
     }
 }
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, FromPrimitive)]
-pub enum PhotometricInterpretation {
+tags! {
+pub enum PhotometricInterpretation(u16) {
     WhiteIsZero = 0,
     BlackIsZero = 1,
     RGB = 2,
@@ -91,9 +91,10 @@ pub enum PhotometricInterpretation {
     YCbCr = 6,
     CIELab = 8,
 }
+}
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, FromPrimitive)]
-pub enum CompressionMethod {
+tags! {
+pub enum CompressionMethod(u16) {
     None = 1,
     Huffman = 2,
     Fax3 = 3,
@@ -104,18 +105,61 @@ pub enum CompressionMethod {
     OldDeflate = 0x80B2,
     PackBits = 0x8005,
 }
+}
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, FromPrimitive)]
-pub enum PlanarConfiguration {
+tags! {
+pub enum PlanarConfiguration(u16) {
     Chunky = 1,
     Planar = 2,
 }
+}
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, FromPrimitive)]
-enum Predictor {
+tags! {
+enum Predictor(u16) {
     None = 1,
     Horizontal = 2,
 }
+}
+
+impl PhotometricInterpretation {
+    pub fn from_u16(val: u16) -> Option<Self> {
+        Self::__from_inner_type(val).ok()
+    }
+
+    pub fn to_u16(&self) -> u16 {
+        Self::__to_inner_type(self)
+    }
+}
+
+impl CompressionMethod {
+    pub fn from_u16(val: u16) -> Option<Self> {
+        Self::__from_inner_type(val).ok()
+    }
+
+    pub fn to_u16(&self) -> u16 {
+        Self::__to_inner_type(self)
+    }
+}
+
+impl PlanarConfiguration {
+    pub fn from_u16(val: u16) -> Option<Self> {
+        Self::__from_inner_type(val).ok()
+    }
+
+    pub fn to_u16(&self) -> u16 {
+        Self::__to_inner_type(self)
+    }
+}
+
+impl Predictor {
+    pub fn from_u16(val: u16) -> Option<Self> {
+        Self::__from_inner_type(val).ok()
+    }
+
+    pub fn to_u16(&self) -> u16 {
+        Self::__to_inner_type(self)
+    }
+}
 
 #[derive(Debug)]
 struct StripDecodeState {
@@ -191,7 +235,7 @@ impl Wrapping for u16 {
 
 fn rev_hpredict_nsamp<T>(image: &mut [T], size: (u32, u32), samples: usize)
 where
-    T: Num + Copy + Wrapping,
+    T: Copy + Wrapping,
 {
     let width = size.0 as usize;
     let height = size.1 as usize;
@@ -334,8 +378,9 @@ impl<R: Read + Seek> Decoder<R> {
         self.width = self.get_tag_u32(ifd::Tag::ImageWidth)?;
         self.height = self.get_tag_u32(ifd::Tag::ImageLength)?;
         self.strip_decoder = None;
-        self.photometric_interpretation = match FromPrimitive::from_u32(
-            self.get_tag_u32(ifd::Tag::PhotometricInterpretation)?
+        // TODO: error on non-SHORT value.
+        self.photometric_interpretation = match PhotometricInterpretation::from_u16(
+            self.get_tag_u32(ifd::Tag::PhotometricInterpretation)? as u16
         ) {
             Some(val) => val,
             None => {
@@ -344,8 +389,9 @@ impl<R: Read + Seek> Decoder<R> {
                 ))
             }
         };
+        // TODO: error on non-SHORT value.
         if let Some(val) = self.find_tag_u32(ifd::Tag::Compression)? {
-            match FromPrimitive::from_u32(val) {
+            match CompressionMethod::from_u16(val as u16) {
                 Some(method) => self.compression_method = method,
                 None => {
                     return Err(TiffError::UnsupportedError(
@@ -454,7 +500,7 @@ impl<R: Read + Seek> Decoder<R> {
     // Value 4 bytes either a pointer the value itself
     fn read_entry(&mut self) -> TiffResult<Option<(ifd::Tag, ifd::Entry)>> {
         let tag = ifd::Tag::from_u16(self.read_short()?);
-        let type_: ifd::Type = match FromPrimitive::from_u16(self.read_short()?) {
+        let type_ = match ifd::Type::from_u16(self.read_short()?) {
             Some(t) => t,
             None => {
                 // Unknown type. Skip this entry according to spec.
@@ -720,7 +766,8 @@ impl<R: Read + Seek> Decoder<R> {
             ));
         }
         if let Ok(predictor) = self.get_tag_u32(ifd::Tag::Predictor) {
-            match FromPrimitive::from_u32(predictor) {
+            // TODO: error on non-SHORT value.
+            match Predictor::from_u16(predictor as u16) {
                 Some(Predictor::None) => (),
                 Some(Predictor::Horizontal) => {
                     rev_hpredict(
@@ -734,6 +781,7 @@ impl<R: Read + Seek> Decoder<R> {
                         predictor,
                     )))
                 }
+                Some(Predictor::__NonExhaustive) => unreachable!(),
             }
         }
         Ok(())

src/encoder/mod.rs

@@ -438,7 +438,7 @@ impl<'a, W: 'a + Write + Seek> DirectoryEncoder<'a, W> {
         }
 
         self.ifd
-            .insert(tag.to_u16(), (<T>::FIELD_TYPE as u16, value.count(), bytes));
+            .insert(tag.to_u16(), (<T>::FIELD_TYPE.to_u16(), value.count(), bytes));
     }
 
     fn write_directory(&mut self) -> TiffResult<u64> {
@@ -565,7 +565,7 @@ impl<'a, W: 'a + Write + Seek, T: ColorType> ImageEncoder<'a, W, T> {
         encoder.write_tag(Tag::Compression, 1u16);
 
         encoder.write_tag(Tag::BitsPerSample, <T>::BITS_PER_SAMPLE);
-        encoder.write_tag(Tag::PhotometricInterpretation, <T>::TIFF_VALUE as u16);
+        encoder.write_tag(Tag::PhotometricInterpretation, <T>::TIFF_VALUE.to_u16());
 
         encoder.write_tag(Tag::RowsPerStrip, rows_per_strip as u32);
 

src/lib.rs

@@ -9,9 +9,6 @@
 extern crate byteorder;
 extern crate lzw;
 extern crate miniz_oxide;
-#[macro_use]
-extern crate num_derive;
-extern crate num_traits;
 
 pub mod decoder;
 pub mod encoder;