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// Copyright 2019-2020 Mozilla Foundation. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// option. This file may not be copied, modified, or distributed
// except according to those terms.
/// Functions to compile human-readable patterns into a mapped_hyph
/// flattened representation of the hyphenation state machine.
use std::io::{Read,BufRead,BufReader,Write,Error,ErrorKind};
use std::collections::HashMap;
use std::convert::TryInto;
use std::hash::{Hash,Hasher};
// Wrap a HashMap so that we can implement the Hash trait.
#[derive(PartialEq, Eq, Clone)]
struct TransitionMap (HashMap<u8,i32>);
impl TransitionMap {
fn new() -> TransitionMap {
TransitionMap(HashMap::<u8,i32>::new())
}
}
impl Hash for TransitionMap {
fn hash<H: Hasher>(&self, state: &mut H) {
// We only look at the values here; that's likely to be enough
// for a reasonable hash.
let mut transitions: Vec<&i32> = self.0.values().collect();
transitions.sort();
for t in transitions {
t.hash(state);
}
}
}
#[derive(PartialEq, Eq, Hash, Clone)]
struct State {
match_string: Option<Vec<u8>>,
#[allow(dead_code)]
repl_string: Option<Vec<u8>>,
#[allow(dead_code)]
repl_index: i32,
#[allow(dead_code)]
repl_cut: i32,
fallback_state: i32,
transitions: TransitionMap,
}
impl State {
fn new() -> State {
State {
match_string: None,
repl_string: None,
repl_index: -1,
repl_cut: -1,
fallback_state: -1,
transitions: TransitionMap::new(),
}
}
}
/// Structures returned by the read_dic_file() function;
/// array of these can then be passed to write_hyf_file()
/// to create the flattened output.
struct LevelBuilder {
states: Vec<State>,
str_to_state: HashMap<Vec<u8>,i32>,
encoding: Option<String>,
nohyphen: Option<String>,
lh_min: u8,
rh_min: u8,
clh_min: u8,
crh_min: u8,
}
impl LevelBuilder {
fn new() -> LevelBuilder {
let mut result = LevelBuilder {
states: Vec::<State>::new(),
str_to_state: HashMap::<Vec<u8>,i32>::new(),
encoding: None,
nohyphen: None,
lh_min: 0,
rh_min: 0,
clh_min: 0,
crh_min: 0,
};
// Initialize the builder with an empty start state.
result.str_to_state.insert(vec![], 0);
result.states.push(State::new());
result
}
fn find_state_number_for(&mut self, text: &[u8]) -> i32 {
let count = self.states.len() as i32;
let index = *self.str_to_state.entry(text.to_vec()).or_insert(count);
if index == count {
self.states.push(State::new());
}
index
}
fn add_pattern(&mut self, pattern: &str) {
let mut bytes = pattern.as_bytes();
let mut text = Vec::<u8>::with_capacity(bytes.len());
let mut digits = Vec::<u8>::with_capacity(bytes.len() + 1);
let mut repl_str = None;
let mut repl_index = 0;
let mut repl_cut = 0;
// Check for replacement rule (non-standard hyphenation spelling change).
if let Some(slash) = bytes.iter().position(|x| *x == b'/') {
let parts = bytes.split_at(slash);
bytes = parts.0;
let mut it = parts.1[1 ..].split(|x| *x == b',');
if let Some(repl) = it.next() {
repl_str = Some(repl.to_vec());
}
if let Some(num) = it.next() {
repl_index = std::str::from_utf8(num).unwrap().parse::<i32>().unwrap() - 1;
}
if let Some(num) = it.next() {
repl_cut = std::str::from_utf8(num).unwrap().parse::<i32>().unwrap();
}
}
// Separate the input pattern into parallel arrays of text (bytes) and digits.
let mut got_digit = false;
for byte in bytes {
if *byte <= b'9' && *byte >= b'0' {
if got_digit {
warn!("invalid pattern \"{}\": consecutive digits", pattern);
return;
}
digits.push(*byte);
got_digit = true;
} else {
text.push(*byte);
if got_digit {
got_digit = false;
} else {
digits.push(b'0');
}
}
}
if !got_digit {
digits.push(b'0');
}
if repl_str.is_none() {
// Optimize away leading zeroes from the digits array.
while !digits.is_empty() && digits[0] == b'0' {
digits.remove(0);
}
} else {
// Convert repl_index and repl_cut from Unicode char to byte indexing.
let start = if text[0] == b'.' { 1 } else { 0 };
if start == 1 {
if digits[0] != b'0' {
warn!("invalid pattern \"{}\": unexpected digit before start of word", pattern);
return;
}
digits.remove(0);
}
let word = std::str::from_utf8(&text[start..]).unwrap();
let mut chars: Vec<_> = word.char_indices().collect();
chars.push((word.len(), '.'));
repl_cut = chars[(repl_index + repl_cut) as usize].0 as i32 - chars[repl_index as usize].0 as i32;
repl_index = chars[repl_index as usize].0 as i32;
}
// Create the new state, or add pattern into an existing state
// (which should not already have a match_string).
let mut state_num = self.find_state_number_for(&text);
let mut state = &mut self.states[state_num as usize];
if state.match_string.is_some() {
warn!("duplicate pattern \"{}\" discarded", pattern);
return;
}
if !digits.is_empty() {
state.match_string = Some(digits);
}
if repl_str.is_some() {
state.repl_string = repl_str;
state.repl_index = repl_index;
state.repl_cut = repl_cut;
}
// Set up prefix transitions, inserting additional states as needed.
while !text.is_empty() {
let last_state = state_num;
let ch = *text.last().unwrap();
text.truncate(text.len() - 1);
state_num = self.find_state_number_for(&text);
if let Some(exists) = self.states[state_num as usize].transitions.0.insert(ch, last_state) {
assert_eq!(exists, last_state, "overwriting existing transition at pattern \"{}\"", pattern);
break;
}
}
}
fn merge_duplicate_states(&mut self) {
// We loop here because when we eliminate a duplicate, and update the transitons
// that referenced it, we may thereby create new duplicates that another pass
// will find and compress further.
loop {
let orig_len = self.states.len();
// Used to map State records to the (first) index at which they occur.
let mut state_to_index = HashMap::<&State,i32>::new();
// Mapping of old->new state indexes, and whether each old state is
// a duplicate that should be dropped.
let mut mappings = Vec::<(i32,bool)>::with_capacity(orig_len);
let mut next_new_index: i32 = 0;
for index in 0 .. self.states.len() {
// Find existing index for this state, or allocate the next new index to it.
let new_index = *state_to_index.entry(&self.states[index]).or_insert(next_new_index);
// Record the mapping, and whether the state was a duplicate.
mappings.push((new_index, new_index != next_new_index));
// If we used next_new_index for this state, increment it.
if new_index == next_new_index {
next_new_index += 1;
}
}
// If we didn't find any duplicates, next_new_index will have kept pace with
// index, so we know we're finished.
if next_new_index as usize == self.states.len() {
break;
}
// Iterate over all the states, either deleting them or updating indexes
// according to the mapping we created; then repeat the search.
for index in (0 .. self.states.len()).rev() {
if mappings[index].1 {
self.states.remove(index);
} else {
let state = &mut self.states[index];
if state.fallback_state != -1 {
state.fallback_state = mappings[state.fallback_state as usize].0;
}
for t in state.transitions.0.iter_mut() {
*t.1 = mappings[*t.1 as usize].0;
}
}
}
}
}
fn flatten(&self) -> Vec<u8> {
// Calculate total space needed for state data, and build the state_to_offset table.
let mut state_data_size = 0;
let mut state_to_offset = Vec::<usize>::with_capacity(self.states.len());
for state in &self.states {
state_to_offset.push(state_data_size);
state_data_size += if state.repl_string.is_some() { 12 } else { 8 };
state_data_size += state.transitions.0.len() * 4;
}
// Helper to map a state index to its offset in the final data block.
let get_state_offset_for = |state_index: i32| -> u32 {
if state_index < 0 {
return super::INVALID_STATE_OFFSET;
}
state_to_offset[state_index as usize] as u32
};
// Helper to map a byte string to its offset in the final data block, and
// store the bytes into string_data unless using an already-existing string.
let mut string_to_offset = HashMap::<Vec<u8>,usize>::new();
let mut string_data = Vec::<u8>::new();
let mut get_string_offset_for = |bytes: &Option<Vec<u8>>| -> u16 {
if bytes.is_none() {
return super::INVALID_STRING_OFFSET;
}
assert!(bytes.as_ref().unwrap().len() < 256);
let new_offset = string_data.len();
let offset = *string_to_offset.entry(bytes.as_ref().unwrap().clone()).or_insert(new_offset);
if offset == new_offset {
string_data.push(bytes.as_ref().unwrap().len() as u8);
string_data.extend_from_slice(bytes.as_ref().unwrap().as_ref());
}
offset.try_into().unwrap()
};
// Handle nohyphen string list if present, converting comma separators to NULs
// and trimming any surplus whitespace.
let mut nohyphen_string_offset: u16 = super::INVALID_STRING_OFFSET;
let mut nohyphen_count: u16 = 0;
if self.nohyphen.is_some() {
let nohyphen_strings: Vec<_> = self.nohyphen.as_ref().unwrap().split(',').map(|x| x.trim()).collect();
nohyphen_count = nohyphen_strings.len().try_into().unwrap();
nohyphen_string_offset = get_string_offset_for(&Some(nohyphen_strings.join("\0").as_bytes().to_vec()));
}
let mut state_data = Vec::<u8>::with_capacity(state_data_size);
for state in &self.states {
state_data.extend(&get_state_offset_for(state.fallback_state).to_le_bytes());
state_data.extend(&get_string_offset_for(&state.match_string).to_le_bytes());
state_data.push(state.transitions.0.len() as u8);
// Determine whether to use an extended state record, and if so add the
// replacement string and index fields.
if state.repl_string.is_none() {
state_data.push(0);
} else {
state_data.push(1);
state_data.extend(&get_string_offset_for(&state.repl_string).to_le_bytes());
state_data.push(state.repl_index as u8);
state_data.push(state.repl_cut as u8);
}
// Collect transitions into an array so we can sort them.
let mut transitions = vec![];
for (key, value) in state.transitions.0.iter() {
transitions.push((*key, get_state_offset_for(*value)))
}
transitions.sort();
for t in transitions {
// New state offset is stored as a 24-bit value, so we do this manually.
state_data.push((t.1 & 0xff) as u8);
state_data.push(((t.1 >> 8) & 0xff) as u8);
state_data.push(((t.1 >> 16) & 0xff) as u8);
state_data.push(t.0);
}
}
assert_eq!(state_data.len(), state_data_size);
// Pad string data to a 4-byte boundary
while string_data.len() & 3 != 0 {
string_data.push(0);
}
let total_size = super::LEVEL_HEADER_SIZE as usize + state_data_size + string_data.len();
let mut result = Vec::<u8>::with_capacity(total_size);
let state_data_base: u32 = super::LEVEL_HEADER_SIZE as u32;
let string_data_base: u32 = state_data_base + state_data_size as u32;
result.extend(&state_data_base.to_le_bytes());
result.extend(&string_data_base.to_le_bytes());
result.extend(&nohyphen_string_offset.to_le_bytes());
result.extend(&nohyphen_count.to_le_bytes());
result.push(self.lh_min);
result.push(self.rh_min);
result.push(self.clh_min);
result.push(self.crh_min);
result.extend(state_data.iter());
result.extend(string_data.iter());
assert_eq!(result.len(), total_size);
result
}
}
/// Read a libhyphen-style pattern file and create the corresponding state
/// machine transitions, etc.
/// The returned Vec can be passed to write_hyf_file() to generate a flattened
/// representation of the state machine in mapped_hyph's binary format.
fn read_dic_file<T: Read>(dic_file: T, compress: bool) -> Result<Vec<LevelBuilder>, &'static str> {
let reader = BufReader::new(dic_file);
let mut builders = Vec::<LevelBuilder>::new();
builders.push(LevelBuilder::new());
let mut builder = &mut builders[0];
for (index, line) in reader.lines().enumerate() {
let mut trimmed = line.unwrap().trim().to_string();
// Strip comments.
if let Some(i) = trimmed.find('%') {
trimmed = trimmed[..i].trim().to_string();
}
// Ignore empty lines.
if trimmed.is_empty() {
continue;
}
// Uppercase indicates keyword rather than pattern.
if trimmed.as_bytes()[0] >= b'A' && trimmed.as_bytes()[0] <= b'Z' {
// First line is encoding; we only support UTF-8.
if builder.encoding.is_none() {
if trimmed != "UTF-8" {
return Err("Only UTF-8 patterns are accepted!");
};
builder.encoding = Some(trimmed);
continue;
}
// Check for valid keyword-value pairs.
if trimmed.contains(' ') {
let parts: Vec<&str> = trimmed.split(' ').collect();
if parts.len() != 2 {
warn!("unrecognized keyword/values: {}", trimmed);
continue;
}
let keyword = parts[0];
let value = parts[1];
match keyword {
"LEFTHYPHENMIN" => builder.lh_min = value.parse::<u8>().unwrap(),
"RIGHTHYPHENMIN" => builder.rh_min = value.parse::<u8>().unwrap(),
"COMPOUNDLEFTHYPHENMIN" => builder.clh_min = value.parse::<u8>().unwrap(),
"COMPOUNDRIGHTHYPHENMIN" => builder.crh_min = value.parse::<u8>().unwrap(),
"NOHYPHEN" => builder.nohyphen = Some(trimmed),
_ => warn!("unknown keyword: {}", trimmed),
}
continue;
}
// Start a new hyphenation level?
if trimmed == "NEXTLEVEL" {
builders.push(LevelBuilder::new());
builder = builders.last_mut().unwrap();
continue;
}
warn!("unknown keyword: {}", trimmed);
continue;
}
// Patterns should always be provided in lowercase; complain if not, and discard
// the bad pattern.
if trimmed != trimmed.to_lowercase() {
warn!("pattern \"{}\" not lowercased at line {}", trimmed, index);
continue;
}
builder.add_pattern(&trimmed);
}
// Create default first (compound-word) level if only one level was provided.
// (Maybe this should be optional? Currently just copying libhyphen behavior.)
if builders.len() == 1 {
let (lh_min, rh_min, clh_min, crh_min) =
(builders[0].lh_min, builders[0].rh_min, builders[0].clh_min, builders[0].crh_min);
builders.insert(0, LevelBuilder::new());
builder = builders.first_mut().unwrap();
builder.add_pattern("1-1");
builder.add_pattern("1'1");
builder.add_pattern("1\u{2013}1"); // en-dash
builder.add_pattern("1\u{2019}1"); // curly apostrophe
builder.nohyphen = Some("',\u{2013},\u{2019},-".to_string());
builder.lh_min = lh_min;
builder.rh_min = rh_min;
builder.clh_min = if clh_min > 0 { clh_min } else if lh_min > 0 { lh_min } else { 3 };
builder.crh_min = if crh_min > 0 { crh_min } else if rh_min > 0 { rh_min } else { 3 };
}
// Put in fallback states in each builder.
for builder in &mut builders {
for (key, state_index) in builder.str_to_state.iter() {
if key.is_empty() {
continue;
}
let mut fallback_key = key.clone();
while !fallback_key.is_empty() {
fallback_key.remove(0);
if builder.str_to_state.contains_key(&fallback_key) {
break;
}
}
builder.states[*state_index as usize].fallback_state = builder.str_to_state[&fallback_key];
}
}
if compress {
// Merge duplicate states to reduce size.
for builder in &mut builders {
builder.merge_duplicate_states();
}
}
Ok(builders)
}
/// Write out the state machines representing a set of hyphenation rules
/// to the given output stream.
fn write_hyf_file<T: Write>(hyf_file: &mut T, levels: Vec<LevelBuilder>) -> std::io::Result<()> {
if levels.is_empty() {
return Err(Error::from(ErrorKind::InvalidData));
}
let mut flattened = vec![];
for level in levels {
flattened.push(level.flatten());
}
// Write file header: magic number, count of levels.
hyf_file.write_all(&[b'H', b'y', b'f', b'0'])?;
let level_count: u32 = flattened.len() as u32;
hyf_file.write_all(&level_count.to_le_bytes())?;
// Write array of offsets to each level. First level will begin immediately
// after the array of offsets.
let mut offset: u32 = super::FILE_HEADER_SIZE as u32 + 4 * level_count;
for flat in &flattened {
hyf_file.write_all(&offset.to_le_bytes())?;
offset += flat.len() as u32;
}
// Write the flattened data for each level.
for flat in &flattened {
hyf_file.write_all(&flat)?;
}
Ok(())
}
/// The public API to the compilation process: reads `dic_file` and writes compiled tables
/// to `hyf_file`. The `compress` param determines whether extra processing to reduce the
/// size of the output is performed.
pub fn compile<T1: Read, T2: Write>(dic_file: T1, hyf_file: &mut T2, compress: bool) -> std::io::Result<()> {
match read_dic_file(dic_file, compress) {
Ok(dic) => write_hyf_file(hyf_file, dic),
Err(e) => {
warn!("parse error: {}", e);
return Err(Error::from(ErrorKind::InvalidData))
}
}
}