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Make huffman decoder/encoder building function return io::Result<_>
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This resolve RazrFalcon/usvg#22
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@sile
sile committed Jul 1, 2018
1 parent 6157daa commit dc77163
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Showing 3 changed files with 36 additions and 28 deletions.
2 changes: 1 addition & 1 deletion src/deflate/encode.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -400,7 +400,7 @@ where
{
self.lz77.flush(&mut self.buf);
self.buf.push(symbol::Symbol::EndOfBlock);
let symbol_encoder = self.huffman.build(&self.buf);
let symbol_encoder = self.huffman.build(&self.buf)?;
self.huffman.save(writer, &symbol_encoder)?;
for s in self.buf.drain(..) {
symbol_encoder.encode(writer, &s)?;
Expand Down
34 changes: 17 additions & 17 deletions src/deflate/symbol.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -232,7 +232,7 @@ impl Decoder {
}

pub trait HuffmanCodec {
fn build(&self, symbols: &[Symbol]) -> Encoder;
fn build(&self, symbols: &[Symbol]) -> io::Result<Encoder>;
fn save<W>(&self, writer: &mut bit::BitWriter<W>, codec: &Encoder) -> io::Result<()>
where
W: io::Write;
Expand All @@ -245,27 +245,27 @@ pub trait HuffmanCodec {
pub struct FixedHuffmanCodec;
impl HuffmanCodec for FixedHuffmanCodec {
#[allow(unused_variables)]
fn build(&self, symbols: &[Symbol]) -> Encoder {
fn build(&self, symbols: &[Symbol]) -> io::Result<Encoder> {
let mut literal_builder = huffman::EncoderBuilder::new(288);
for &(bitwidth, ref symbols, code_base) in &FIXED_LITERAL_OR_LENGTH_CODE_TABLE {
for (code, symbol) in symbols
.clone()
.enumerate()
.map(|(i, s)| (code_base + i as u16, s))
{
literal_builder.set_mapping(symbol, huffman::Code::new(bitwidth, code));
literal_builder.set_mapping(symbol, huffman::Code::new(bitwidth, code))?;
}
}

let mut distance_builder = huffman::EncoderBuilder::new(30);
for i in 0..30 {
distance_builder.set_mapping(i, huffman::Code::new(5, i));
distance_builder.set_mapping(i, huffman::Code::new(5, i))?;
}

Encoder {
Ok(Encoder {
literal: literal_builder.finish(),
distance: distance_builder.finish(),
}
})
}
#[allow(unused_variables)]
fn save<W>(&self, writer: &mut bit::BitWriter<W>, codec: &Encoder) -> io::Result<()>
Expand All @@ -286,13 +286,13 @@ impl HuffmanCodec for FixedHuffmanCodec {
.enumerate()
.map(|(i, s)| (code_base + i as u16, s))
{
literal_builder.set_mapping(symbol, huffman::Code::new(bitwidth, code));
literal_builder.set_mapping(symbol, huffman::Code::new(bitwidth, code))?;
}
}

let mut distance_builder = huffman::DecoderBuilder::new(5, None);
for i in 0..30 {
distance_builder.set_mapping(i, huffman::Code::new(5, i));
distance_builder.set_mapping(i, huffman::Code::new(5, i))?;
}

Ok(Decoder {
Expand All @@ -305,7 +305,7 @@ impl HuffmanCodec for FixedHuffmanCodec {
#[derive(Debug)]
pub struct DynamicHuffmanCodec;
impl HuffmanCodec for DynamicHuffmanCodec {
fn build(&self, symbols: &[Symbol]) -> Encoder {
fn build(&self, symbols: &[Symbol]) -> io::Result<Encoder> {
let mut literal_counts = [0; 286];
let mut distance_counts = [0; 30];
for s in symbols {
Expand All @@ -314,10 +314,10 @@ impl HuffmanCodec for DynamicHuffmanCodec {
distance_counts[d as usize] += 1;
}
}
Encoder {
literal: huffman::EncoderBuilder::from_frequencies(&literal_counts, 15),
distance: huffman::EncoderBuilder::from_frequencies(&distance_counts, 15),
}
Ok(Encoder {
literal: huffman::EncoderBuilder::from_frequencies(&literal_counts, 15)?,
distance: huffman::EncoderBuilder::from_frequencies(&distance_counts, 15)?,
})
}
fn save<W>(&self, writer: &mut bit::BitWriter<W>, codec: &Encoder) -> io::Result<()>
where
Expand All @@ -331,7 +331,7 @@ impl HuffmanCodec for DynamicHuffmanCodec {
for x in &codes {
code_counts[x.0 as usize] += 1;
}
let bitwidth_encoder = huffman::EncoderBuilder::from_frequencies(&code_counts, 7);
let bitwidth_encoder = huffman::EncoderBuilder::from_frequencies(&code_counts, 7)?;

let bitwidth_code_count = cmp::max(
4,
Expand Down Expand Up @@ -379,7 +379,7 @@ impl HuffmanCodec for DynamicHuffmanCodec {
bitwidth_code_bitwidthes[i] = reader.read_bits(3)? as u8;
}
let bitwidth_decoder =
huffman::DecoderBuilder::from_bitwidthes(&bitwidth_code_bitwidthes, None);
huffman::DecoderBuilder::from_bitwidthes(&bitwidth_code_bitwidthes, None)?;

let mut literal_code_bitwidthes = Vec::with_capacity(literal_code_count as usize);
while literal_code_bitwidthes.len() < literal_code_count as usize {
Expand Down Expand Up @@ -412,8 +412,8 @@ impl HuffmanCodec for DynamicHuffmanCodec {
literal: huffman::DecoderBuilder::from_bitwidthes(
&literal_code_bitwidthes,
Some(END_OF_BLOCK),
),
distance: huffman::DecoderBuilder::from_bitwidthes(&distance_code_bitwidthes, None),
)?,
distance: huffman::DecoderBuilder::from_bitwidthes(&distance_code_bitwidthes, None)?,
})
}
}
Expand Down
28 changes: 18 additions & 10 deletions src/huffman.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -34,9 +34,9 @@ impl Code {

pub trait Builder: Sized {
type Instance;
fn set_mapping(&mut self, symbol: u16, code: Code);
fn set_mapping(&mut self, symbol: u16, code: Code) -> io::Result<()>;
fn finish(self) -> Self::Instance;
fn restore_canonical_huffman_codes(mut self, bitwidthes: &[u8]) -> Self::Instance {
fn restore_canonical_huffman_codes(mut self, bitwidthes: &[u8]) -> io::Result<Self::Instance> {
debug_assert!(!bitwidthes.is_empty());

let mut symbols = bitwidthes
Expand All @@ -51,11 +51,11 @@ pub trait Builder: Sized {
let mut prev_width = 0;
for (symbol, bitwidth) in symbols {
code <<= bitwidth - prev_width;
self.set_mapping(symbol, Code::new(bitwidth, code));
self.set_mapping(symbol, Code::new(bitwidth, code))?;
code += 1;
prev_width = bitwidth;
}
self.finish()
Ok(self.finish())
}
}

Expand All @@ -75,14 +75,14 @@ impl DecoderBuilder {
max_bitwidth: max_bitwidth,
}
}
pub fn from_bitwidthes(bitwidthes: &[u8], eob_symbol: Option<u16>) -> Decoder {
pub fn from_bitwidthes(bitwidthes: &[u8], eob_symbol: Option<u16>) -> io::Result<Decoder> {
let builder = Self::new(bitwidthes.iter().cloned().max().unwrap_or(0), eob_symbol);
builder.restore_canonical_huffman_codes(bitwidthes)
}
}
impl Builder for DecoderBuilder {
type Instance = Decoder;
fn set_mapping(&mut self, symbol: u16, code: Code) {
fn set_mapping(&mut self, symbol: u16, code: Code) -> io::Result<()> {
debug_assert!(code.width <= self.max_bitwidth);
if Some(symbol) == self.eob_symbol {
self.eob_bitwidth = code.width;
Expand All @@ -95,11 +95,18 @@ impl Builder for DecoderBuilder {
let code_be = code.inverse_endian();
for padding in 0..(1 << (self.max_bitwidth - code.width)) {
let i = ((padding << code.width) | code_be.bits) as usize;
debug_assert_eq!(self.table[i], u16::from(MAX_BITWIDTH) + 1);
if self.table[i] != u16::from(MAX_BITWIDTH) + 1 {
let message = format!(
"Bit region conflict: i={}, old_value={}, new_value={}, symbol={}, code={:?}",
i, self.table[i], value, symbol, code
);
return Err(io::Error::new(io::ErrorKind::InvalidData, message));
}
unsafe {
*self.table.get_unchecked_mut(i) = value;
}
}
Ok(())
}
fn finish(self) -> Self::Instance {
Decoder {
Expand Down Expand Up @@ -158,7 +165,7 @@ impl EncoderBuilder {
table: vec![Code::new(0, 0); symbol_count],
}
}
pub fn from_bitwidthes(bitwidthes: &[u8]) -> Encoder {
pub fn from_bitwidthes(bitwidthes: &[u8]) -> io::Result<Encoder> {
let symbol_count = bitwidthes
.iter()
.enumerate()
Expand All @@ -168,7 +175,7 @@ impl EncoderBuilder {
let builder = Self::new(symbol_count);
builder.restore_canonical_huffman_codes(bitwidthes)
}
pub fn from_frequencies(symbol_frequencies: &[usize], max_bitwidth: u8) -> Encoder {
pub fn from_frequencies(symbol_frequencies: &[usize], max_bitwidth: u8) -> io::Result<Encoder> {
let max_bitwidth = cmp::min(
max_bitwidth,
ordinary_huffman_codes::calc_optimal_max_bitwidth(symbol_frequencies),
Expand All @@ -179,9 +186,10 @@ impl EncoderBuilder {
}
impl Builder for EncoderBuilder {
type Instance = Encoder;
fn set_mapping(&mut self, symbol: u16, code: Code) {
fn set_mapping(&mut self, symbol: u16, code: Code) -> io::Result<()> {
debug_assert_eq!(self.table[symbol as usize], Code::new(0, 0));
self.table[symbol as usize] = code.inverse_endian();
Ok(())
}
fn finish(self) -> Self::Instance {
Encoder { table: self.table }
Expand Down

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