Move code into cli directory
This commit is contained in:
Max Brunsfeld
parent
b8dd5d2640
commit
5b0e12ea33
29 changed files with 32 additions and 26 deletions
735
cli/src/build_tables/build_parse_table.rs
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735
cli/src/build_tables/build_parse_table.rs
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@ -0,0 +1,735 @@
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use super::item::{LookaheadSet, ParseItem, ParseItemSet};
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use super::item_set_builder::ParseItemSetBuilder;
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use crate::error::{Error, Result};
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use crate::grammars::{InlinedProductionMap, LexicalGrammar, SyntaxGrammar, VariableType};
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use crate::rules::{Alias, Associativity, Symbol, SymbolType};
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use crate::tables::{
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AliasSequenceId, ParseAction, ParseState, ParseStateId, ParseTable, ParseTableEntry,
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};
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use core::ops::Range;
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use hashbrown::hash_map::Entry;
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use hashbrown::{HashMap, HashSet};
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use std::collections::hash_map::DefaultHasher;
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use std::collections::VecDeque;
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use std::fmt::Write;
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use std::hash::Hasher;
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#[derive(Clone)]
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struct AuxiliarySymbolInfo {
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auxiliary_symbol: Symbol,
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parent_symbols: Vec<Symbol>,
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}
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type SymbolSequence = Vec<Symbol>;
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type AuxiliarySymbolSequence = Vec<AuxiliarySymbolInfo>;
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struct ParseStateQueueEntry {
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preceding_symbols: SymbolSequence,
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preceding_auxiliary_symbols: AuxiliarySymbolSequence,
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state_id: ParseStateId,
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}
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struct ParseTableBuilder<'a> {
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item_set_builder: ParseItemSetBuilder<'a>,
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syntax_grammar: &'a SyntaxGrammar,
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lexical_grammar: &'a LexicalGrammar,
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state_ids_by_item_set: HashMap<ParseItemSet<'a>, ParseStateId>,
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item_sets_by_state_id: Vec<ParseItemSet<'a>>,
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parse_state_queue: VecDeque<ParseStateQueueEntry>,
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parse_table: ParseTable,
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following_tokens: Vec<LookaheadSet>,
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state_ids_to_log: Vec<ParseStateId>,
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}
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impl<'a> ParseTableBuilder<'a> {
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fn build(mut self) -> Result<(ParseTable, Vec<LookaheadSet>)> {
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// Ensure that the empty alias sequence has index 0.
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self.parse_table.alias_sequences.push(Vec::new());
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// Add the error state at index 0.
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self.add_parse_state(&Vec::new(), &Vec::new(), ParseItemSet::default());
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// Add the starting state at index 1.
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self.add_parse_state(
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&Vec::new(),
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&Vec::new(),
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ParseItemSet::with(
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[(
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ParseItem::start(),
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LookaheadSet::with([Symbol::end()].iter().cloned()),
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)]
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.iter()
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.cloned(),
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),
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);
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while let Some(entry) = self.parse_state_queue.pop_front() {
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let item_set = self
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.item_set_builder
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.transitive_closure(&self.item_sets_by_state_id[entry.state_id]);
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if self.state_ids_to_log.contains(&entry.state_id) {
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eprintln!(
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"state: {}\n\ninitial item set:\n\n{}closed item set:\n\n{}",
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entry.state_id,
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super::item::ParseItemSetDisplay(
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&self.item_sets_by_state_id[entry.state_id],
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self.syntax_grammar,
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self.lexical_grammar,
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),
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super::item::ParseItemSetDisplay(
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&item_set,
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self.syntax_grammar,
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self.lexical_grammar,
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)
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);
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}
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self.add_actions(
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entry.preceding_symbols,
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entry.preceding_auxiliary_symbols,
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entry.state_id,
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item_set,
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)?;
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}
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self.populate_used_symbols();
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self.remove_precedences();
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Ok((self.parse_table, self.following_tokens))
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}
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fn add_parse_state(
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&mut self,
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preceding_symbols: &SymbolSequence,
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preceding_auxiliary_symbols: &AuxiliarySymbolSequence,
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item_set: ParseItemSet<'a>,
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) -> ParseStateId {
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if preceding_symbols.len() > 1 {
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let left_tokens = self
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.item_set_builder
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.last_set(&preceding_symbols[preceding_symbols.len() - 2]);
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let right_tokens = self
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.item_set_builder
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.first_set(&preceding_symbols[preceding_symbols.len() - 1]);
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for left_token in left_tokens.iter() {
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if left_token.is_terminal() {
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self.following_tokens[left_token.index].insert_all(right_tokens);
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}
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}
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}
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let mut hasher = DefaultHasher::new();
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item_set.hash_unfinished_items(&mut hasher);
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let unfinished_item_signature = hasher.finish();
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match self.state_ids_by_item_set.entry(item_set) {
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Entry::Occupied(o) => *o.get(),
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Entry::Vacant(v) => {
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let state_id = self.parse_table.states.len();
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self.item_sets_by_state_id.push(v.key().clone());
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self.parse_table.states.push(ParseState {
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lex_state_id: 0,
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terminal_entries: HashMap::new(),
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nonterminal_entries: HashMap::new(),
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unfinished_item_signature,
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});
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self.parse_state_queue.push_back(ParseStateQueueEntry {
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state_id,
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preceding_symbols: preceding_symbols.clone(),
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preceding_auxiliary_symbols: preceding_auxiliary_symbols.clone(),
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});
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v.insert(state_id);
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state_id
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}
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}
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}
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fn add_actions(
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&mut self,
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mut preceding_symbols: SymbolSequence,
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mut preceding_auxiliary_symbols: Vec<AuxiliarySymbolInfo>,
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state_id: ParseStateId,
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item_set: ParseItemSet<'a>,
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) -> Result<()> {
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let mut terminal_successors = HashMap::new();
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let mut non_terminal_successors = HashMap::new();
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let mut lookaheads_with_conflicts = HashSet::new();
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for (item, lookaheads) in &item_set.entries {
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if let Some(next_symbol) = item.symbol() {
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let successor = item.successor();
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if next_symbol.is_non_terminal() {
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// Keep track of where auxiliary non-terminals (repeat symbols) are
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// used within visible symbols. This information may be needed later
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// for conflict resolution.
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if self.syntax_grammar.variables[next_symbol.index].is_auxiliary() {
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preceding_auxiliary_symbols
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.push(self.get_auxiliary_node_info(&item_set, next_symbol));
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}
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non_terminal_successors
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.entry(next_symbol)
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.or_insert_with(|| ParseItemSet::default())
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.entries
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.entry(successor)
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.or_insert_with(|| LookaheadSet::new())
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.insert_all(lookaheads);
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} else {
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terminal_successors
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.entry(next_symbol)
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.or_insert_with(|| ParseItemSet::default())
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.entries
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.entry(successor)
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.or_insert_with(|| LookaheadSet::new())
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.insert_all(lookaheads);
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}
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} else {
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let action = if item.is_augmented() {
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ParseAction::Accept
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} else {
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ParseAction::Reduce {
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symbol: Symbol::non_terminal(item.variable_index as usize),
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child_count: item.step_index as usize,
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precedence: item.precedence(),
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associativity: item.associativity(),
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dynamic_precedence: item.production.dynamic_precedence,
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alias_sequence_id: self.get_alias_sequence_id(item),
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}
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};
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for lookahead in lookaheads.iter() {
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let entry = self.parse_table.states[state_id]
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.terminal_entries
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.entry(lookahead);
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let entry = entry.or_insert_with(|| ParseTableEntry::new());
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if entry.actions.is_empty() {
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entry.actions.push(action);
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} else if action.precedence() > entry.actions[0].precedence() {
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entry.actions.clear();
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entry.actions.push(action);
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lookaheads_with_conflicts.remove(&lookahead);
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} else if action.precedence() == entry.actions[0].precedence() {
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entry.actions.push(action);
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lookaheads_with_conflicts.insert(lookahead);
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}
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}
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}
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}
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for (symbol, next_item_set) in terminal_successors {
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preceding_symbols.push(symbol);
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let next_state_id = self.add_parse_state(
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&preceding_symbols,
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&preceding_auxiliary_symbols,
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next_item_set,
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);
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preceding_symbols.pop();
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let entry = self.parse_table.states[state_id]
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.terminal_entries
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.entry(symbol);
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if let Entry::Occupied(e) = &entry {
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if !e.get().actions.is_empty() {
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lookaheads_with_conflicts.insert(symbol);
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}
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}
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entry
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.or_insert_with(|| ParseTableEntry::new())
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.actions
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.push(ParseAction::Shift {
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state: next_state_id,
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is_repetition: false,
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});
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}
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for (symbol, next_item_set) in non_terminal_successors {
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preceding_symbols.push(symbol);
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let next_state_id = self.add_parse_state(
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&preceding_symbols,
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&preceding_auxiliary_symbols,
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next_item_set,
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);
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preceding_symbols.pop();
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self.parse_table.states[state_id]
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.nonterminal_entries
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.insert(symbol, next_state_id);
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}
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for symbol in lookaheads_with_conflicts {
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self.handle_conflict(
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&item_set,
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state_id,
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&preceding_symbols,
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&preceding_auxiliary_symbols,
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symbol,
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)?;
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}
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let state = &mut self.parse_table.states[state_id];
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for extra_token in &self.syntax_grammar.extra_tokens {
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state
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.terminal_entries
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.entry(*extra_token)
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.or_insert(ParseTableEntry {
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reusable: true,
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actions: vec![ParseAction::ShiftExtra],
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});
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}
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Ok(())
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}
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fn handle_conflict(
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&mut self,
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item_set: &ParseItemSet,
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state_id: ParseStateId,
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preceding_symbols: &SymbolSequence,
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preceding_auxiliary_symbols: &Vec<AuxiliarySymbolInfo>,
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conflicting_lookahead: Symbol,
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) -> Result<()> {
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let entry = self.parse_table.states[state_id]
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.terminal_entries
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.get_mut(&conflicting_lookahead)
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.unwrap();
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// Determine which items in the set conflict with each other, and the
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// precedences associated with SHIFT vs REDUCE actions. There won't
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// be multiple REDUCE actions with different precedences; that is
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// sorted out ahead of time in `add_actions`. But there can still be
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// REDUCE-REDUCE conflicts where all actions have the *same*
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// precedence, and there can still be SHIFT/REDUCE conflicts.
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let reduce_precedence = entry.actions[0].precedence();
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let mut considered_associativity = false;
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let mut shift_precedence: Option<Range<i32>> = None;
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let mut conflicting_items = HashSet::new();
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for (item, lookaheads) in &item_set.entries {
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if let Some(step) = item.step() {
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if item.step_index > 0 {
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if self
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.item_set_builder
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.first_set(&step.symbol)
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.contains(&conflicting_lookahead)
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{
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conflicting_items.insert(item);
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let precedence = item.precedence();
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if let Some(range) = &mut shift_precedence {
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if precedence < range.start {
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range.start = precedence;
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} else if precedence > range.end {
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range.end = precedence;
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}
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} else {
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shift_precedence = Some(precedence..precedence);
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}
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}
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}
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} else if lookaheads.contains(&conflicting_lookahead) {
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conflicting_items.insert(item);
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}
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}
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if let ParseAction::Shift { is_repetition, .. } = entry.actions.last_mut().unwrap() {
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let shift_precedence = shift_precedence.unwrap_or(0..0);
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// If all of the items in the conflict have the same parent symbol,
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// and that parent symbols is auxiliary, then this is just the intentional
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// ambiguity associated with a repeat rule. Resolve that class of ambiguity
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// by leaving it in the parse table, but marking the SHIFT action with
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// an `is_repetition` flag.
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let conflicting_variable_index =
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conflicting_items.iter().next().unwrap().variable_index;
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if self.syntax_grammar.variables[conflicting_variable_index as usize].is_auxiliary() {
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if conflicting_items
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.iter()
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.all(|item| item.variable_index == conflicting_variable_index)
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{
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*is_repetition = true;
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return Ok(());
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}
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}
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// If the SHIFT action has higher precedence, remove all the REDUCE actions.
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if shift_precedence.start > reduce_precedence
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|| (shift_precedence.start == reduce_precedence
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&& shift_precedence.end > reduce_precedence)
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{
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entry.actions.drain(0..entry.actions.len() - 1);
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}
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// If the REDUCE actions have higher precedence, remove the SHIFT action.
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else if shift_precedence.end < reduce_precedence
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|| (shift_precedence.end == reduce_precedence
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&& shift_precedence.start < reduce_precedence)
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{
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entry.actions.pop();
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conflicting_items.retain(|item| item.is_done());
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}
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// If the SHIFT and REDUCE actions have the same predence, consider
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// the REDUCE actions' associativity.
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else if shift_precedence == (reduce_precedence..reduce_precedence) {
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considered_associativity = true;
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let mut has_left = false;
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let mut has_right = false;
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let mut has_non = false;
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for action in &entry.actions {
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if let ParseAction::Reduce { associativity, .. } = action {
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match associativity {
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Some(Associativity::Left) => has_left = true,
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Some(Associativity::Right) => has_right = true,
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None => has_non = true,
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}
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}
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}
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// If all reduce actions are left associative, remove the SHIFT action.
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// If all reduce actions are right associative, remove the REDUCE actions.
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match (has_left, has_non, has_right) {
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(true, false, false) => {
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entry.actions.pop();
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conflicting_items.retain(|item| item.is_done());
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}
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(false, false, true) => {
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entry.actions.drain(0..entry.actions.len() - 1);
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}
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_ => {}
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}
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}
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}
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// If all of the actions but one have been eliminated, then there's no problem.
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let entry = self.parse_table.states[state_id]
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.terminal_entries
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.get_mut(&conflicting_lookahead)
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.unwrap();
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if entry.actions.len() == 1 {
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return Ok(());
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}
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|
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// Determine the set of parent symbols involved in this conflict.
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let mut actual_conflict = Vec::new();
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for item in &conflicting_items {
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let symbol = Symbol::non_terminal(item.variable_index as usize);
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if self.syntax_grammar.variables[symbol.index].is_auxiliary() {
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actual_conflict.extend(
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preceding_auxiliary_symbols
|
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.iter()
|
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.rev()
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.find_map(|info| {
|
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if info.auxiliary_symbol == symbol {
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Some(&info.parent_symbols)
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} else {
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None
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}
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})
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.unwrap()
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.iter(),
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);
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} else {
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actual_conflict.push(symbol);
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}
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}
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actual_conflict.sort_unstable();
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actual_conflict.dedup();
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|
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// If this set of symbols has been whitelisted, then there's no error.
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if self
|
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.syntax_grammar
|
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.expected_conflicts
|
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.contains(&actual_conflict)
|
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{
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return Ok(());
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}
|
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|
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let mut msg = "Unresolved conflict for symbol sequence:\n\n".to_string();
|
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for symbol in preceding_symbols {
|
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write!(&mut msg, " {}", self.symbol_name(symbol)).unwrap();
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}
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|
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write!(
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&mut msg,
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" • {} …\n\n",
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self.symbol_name(&conflicting_lookahead)
|
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)
|
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.unwrap();
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write!(&mut msg, "Possible interpretations:\n\n").unwrap();
|
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for (i, item) in conflicting_items.iter().enumerate() {
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write!(&mut msg, " {}:", i + 1).unwrap();
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|
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for preceding_symbol in preceding_symbols
|
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.iter()
|
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.take(preceding_symbols.len() - item.step_index as usize)
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{
|
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write!(&mut msg, " {}", self.symbol_name(preceding_symbol)).unwrap();
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}
|
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write!(
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&mut msg,
|
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" ({}",
|
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&self.syntax_grammar.variables[item.variable_index as usize].name
|
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)
|
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.unwrap();
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|
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for (j, step) in item.production.steps.iter().enumerate() {
|
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if j as u32 == item.step_index {
|
||||
write!(&mut msg, " •").unwrap();
|
||||
}
|
||||
write!(&mut msg, " {}", self.symbol_name(&step.symbol)).unwrap();
|
||||
}
|
||||
|
||||
write!(&mut msg, ")").unwrap();
|
||||
|
||||
if item.is_done() {
|
||||
write!(
|
||||
&mut msg,
|
||||
" • {}",
|
||||
self.symbol_name(&conflicting_lookahead)
|
||||
)
|
||||
.unwrap();
|
||||
}
|
||||
|
||||
let precedence = item.precedence();
|
||||
let associativity = item.associativity();
|
||||
if precedence != 0 || associativity.is_some() {
|
||||
write!(
|
||||
&mut msg,
|
||||
"(precedence: {}, associativity: {:?})",
|
||||
precedence, associativity
|
||||
)
|
||||
.unwrap();
|
||||
}
|
||||
|
||||
write!(&mut msg, "\n").unwrap();
|
||||
}
|
||||
|
||||
let mut resolution_count = 0;
|
||||
write!(&mut msg, "\nPossible resolutions:\n\n").unwrap();
|
||||
let shift_items = conflicting_items
|
||||
.iter()
|
||||
.filter(|i| !i.is_done())
|
||||
.cloned()
|
||||
.collect::<Vec<_>>();
|
||||
if shift_items.len() > 0 {
|
||||
resolution_count += 1;
|
||||
write!(
|
||||
&mut msg,
|
||||
" {}: Specify a higher precedence in",
|
||||
resolution_count
|
||||
)
|
||||
.unwrap();
|
||||
for (i, item) in shift_items.iter().enumerate() {
|
||||
if i > 0 {
|
||||
write!(&mut msg, " and").unwrap();
|
||||
}
|
||||
write!(
|
||||
&mut msg,
|
||||
" `{}`",
|
||||
self.symbol_name(&Symbol::non_terminal(item.variable_index as usize))
|
||||
)
|
||||
.unwrap();
|
||||
}
|
||||
write!(&mut msg, " than in the other rules.\n").unwrap();
|
||||
}
|
||||
|
||||
if considered_associativity {
|
||||
resolution_count += 1;
|
||||
write!(
|
||||
&mut msg,
|
||||
" {}: Specify a left or right associativity in ",
|
||||
resolution_count
|
||||
)
|
||||
.unwrap();
|
||||
for (i, item) in conflicting_items.iter().filter(|i| i.is_done()).enumerate() {
|
||||
if i > 0 {
|
||||
write!(&mut msg, " and ").unwrap();
|
||||
}
|
||||
write!(
|
||||
&mut msg,
|
||||
"{}",
|
||||
self.symbol_name(&Symbol::non_terminal(item.variable_index as usize))
|
||||
)
|
||||
.unwrap();
|
||||
}
|
||||
write!(&mut msg, "\n").unwrap();
|
||||
}
|
||||
|
||||
for item in &conflicting_items {
|
||||
if item.is_done() {
|
||||
resolution_count += 1;
|
||||
write!(
|
||||
&mut msg,
|
||||
" {}: Specify a higher precedence in `{}` than in the other rules.\n",
|
||||
resolution_count,
|
||||
self.symbol_name(&Symbol::non_terminal(item.variable_index as usize))
|
||||
)
|
||||
.unwrap();
|
||||
}
|
||||
}
|
||||
|
||||
resolution_count += 1;
|
||||
write!(
|
||||
&mut msg,
|
||||
" {}: Add a conflict for these rules: ",
|
||||
resolution_count
|
||||
)
|
||||
.unwrap();
|
||||
for (i, symbol) in actual_conflict.iter().enumerate() {
|
||||
if i > 0 {
|
||||
write!(&mut msg, ", ").unwrap();
|
||||
}
|
||||
write!(&mut msg, "{}", self.symbol_name(symbol)).unwrap();
|
||||
}
|
||||
write!(&mut msg, "\n").unwrap();
|
||||
|
||||
Err(Error(msg))
|
||||
}
|
||||
|
||||
fn get_auxiliary_node_info(
|
||||
&self,
|
||||
item_set: &ParseItemSet,
|
||||
symbol: Symbol,
|
||||
) -> AuxiliarySymbolInfo {
|
||||
let parent_symbols = item_set
|
||||
.entries
|
||||
.keys()
|
||||
.filter_map(|item| {
|
||||
let variable_index = item.variable_index as usize;
|
||||
if item.symbol() == Some(symbol)
|
||||
&& !self.syntax_grammar.variables[variable_index].is_auxiliary()
|
||||
{
|
||||
Some(Symbol::non_terminal(variable_index))
|
||||
} else {
|
||||
None
|
||||
}
|
||||
})
|
||||
.collect();
|
||||
AuxiliarySymbolInfo {
|
||||
auxiliary_symbol: symbol,
|
||||
parent_symbols,
|
||||
}
|
||||
}
|
||||
|
||||
fn populate_used_symbols(&mut self) {
|
||||
let mut terminal_usages = vec![false; self.lexical_grammar.variables.len()];
|
||||
let mut non_terminal_usages = vec![false; self.syntax_grammar.variables.len()];
|
||||
let mut external_usages = vec![false; self.syntax_grammar.external_tokens.len()];
|
||||
for state in &self.parse_table.states {
|
||||
for symbol in state.terminal_entries.keys() {
|
||||
match symbol.kind {
|
||||
SymbolType::Terminal => terminal_usages[symbol.index] = true,
|
||||
SymbolType::External => external_usages[symbol.index] = true,
|
||||
_ => {}
|
||||
}
|
||||
}
|
||||
for symbol in state.nonterminal_entries.keys() {
|
||||
non_terminal_usages[symbol.index] = true;
|
||||
}
|
||||
}
|
||||
for (i, value) in external_usages.into_iter().enumerate() {
|
||||
if value {
|
||||
self.parse_table.symbols.push(Symbol::external(i));
|
||||
}
|
||||
}
|
||||
self.parse_table.symbols.push(Symbol::end());
|
||||
for (i, value) in terminal_usages.into_iter().enumerate() {
|
||||
if value {
|
||||
self.parse_table.symbols.push(Symbol::terminal(i));
|
||||
}
|
||||
}
|
||||
for (i, value) in non_terminal_usages.into_iter().enumerate() {
|
||||
if value {
|
||||
self.parse_table.symbols.push(Symbol::non_terminal(i));
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn remove_precedences(&mut self) {
|
||||
for state in self.parse_table.states.iter_mut() {
|
||||
for (_, entry) in state.terminal_entries.iter_mut() {
|
||||
for action in entry.actions.iter_mut() {
|
||||
match action {
|
||||
ParseAction::Reduce {
|
||||
precedence,
|
||||
associativity,
|
||||
..
|
||||
} => {
|
||||
*precedence = 0;
|
||||
*associativity = None;
|
||||
}
|
||||
_ => {}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn get_alias_sequence_id(&mut self, item: &ParseItem) -> AliasSequenceId {
|
||||
let mut alias_sequence: Vec<Option<Alias>> = item
|
||||
.production
|
||||
.steps
|
||||
.iter()
|
||||
.map(|s| s.alias.clone())
|
||||
.collect();
|
||||
while alias_sequence.last() == Some(&None) {
|
||||
alias_sequence.pop();
|
||||
}
|
||||
if item.production.steps.len() > self.parse_table.max_aliased_production_length {
|
||||
self.parse_table.max_aliased_production_length = item.production.steps.len()
|
||||
}
|
||||
if let Some(index) = self
|
||||
.parse_table
|
||||
.alias_sequences
|
||||
.iter()
|
||||
.position(|seq| *seq == alias_sequence)
|
||||
{
|
||||
index
|
||||
} else {
|
||||
self.parse_table.alias_sequences.push(alias_sequence);
|
||||
self.parse_table.alias_sequences.len() - 1
|
||||
}
|
||||
}
|
||||
|
||||
fn symbol_name(&self, symbol: &Symbol) -> String {
|
||||
match symbol.kind {
|
||||
SymbolType::End => "EOF".to_string(),
|
||||
SymbolType::External => self.syntax_grammar.external_tokens[symbol.index]
|
||||
.name
|
||||
.clone(),
|
||||
SymbolType::NonTerminal => self.syntax_grammar.variables[symbol.index].name.clone(),
|
||||
SymbolType::Terminal => {
|
||||
let variable = &self.lexical_grammar.variables[symbol.index];
|
||||
if variable.kind == VariableType::Named {
|
||||
variable.name.clone()
|
||||
} else {
|
||||
format!("\"{}\"", &variable.name)
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
pub(crate) fn build_parse_table(
|
||||
syntax_grammar: &SyntaxGrammar,
|
||||
lexical_grammar: &LexicalGrammar,
|
||||
inlines: &InlinedProductionMap,
|
||||
state_ids_to_log: Vec<usize>,
|
||||
) -> Result<(ParseTable, Vec<LookaheadSet>)> {
|
||||
ParseTableBuilder {
|
||||
syntax_grammar,
|
||||
lexical_grammar,
|
||||
state_ids_to_log,
|
||||
item_set_builder: ParseItemSetBuilder::new(syntax_grammar, lexical_grammar, inlines),
|
||||
state_ids_by_item_set: HashMap::new(),
|
||||
item_sets_by_state_id: Vec::new(),
|
||||
parse_state_queue: VecDeque::new(),
|
||||
parse_table: ParseTable {
|
||||
states: Vec::new(),
|
||||
symbols: Vec::new(),
|
||||
alias_sequences: Vec::new(),
|
||||
max_aliased_production_length: 0,
|
||||
},
|
||||
following_tokens: vec![LookaheadSet::new(); lexical_grammar.variables.len()],
|
||||
}
|
||||
.build()
|
||||
}
|
||||
Loading…
Add table
Add a link
Reference in a new issue