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use std::borrow::Cow;
use std::collections::BTreeMap;
use input::ast::{Stmts, Rhs, RhsAst};
use input::FragmentId;
use middle::flatten_stmts::{Path, Position};
#[derive(Debug)]
pub struct Trace {
pub tokens: BTreeMap<Path, TraceToken>,
pub stmt_positions: Vec<StmtTokenPosition>,
pub rule_tokens: Vec<BTreeMap<Option<usize>, usize>>,
}
#[derive(Debug)]
pub struct StmtTokenPosition {
lhs: Option<FragmentId>,
position: usize,
}
#[derive(Debug, Eq, PartialEq)]
pub enum TraceToken {
Fragment(FragmentId),
Quote,
String(String),
LParen,
RParen,
Star,
Plus,
EmptyProduct,
Alternative,
PrecedencedAlternative,
}
impl TraceToken {
pub fn as_str(&self, fragment_names: &BTreeMap<FragmentId, String>) -> Cow<str> {
match self {
&TraceToken::LParen => Cow::Borrowed("("),
&TraceToken::RParen => Cow::Borrowed(")"),
&TraceToken::Star => Cow::Borrowed("*"),
&TraceToken::Plus => Cow::Borrowed("+"),
&TraceToken::EmptyProduct => Cow::Borrowed("()"),
&TraceToken::Alternative => Cow::Borrowed("|"),
&TraceToken::PrecedencedAlternative => Cow::Borrowed("|>"),
&TraceToken::Quote => Cow::Borrowed("\""),
&TraceToken::String(ref name) => Cow::Owned(name.as_str().to_string()),
&TraceToken::Fragment(fragment_id) => {
Cow::Owned(fragment_names[&fragment_id].clone())
},
}
}
}
impl Trace {
pub fn from_stmts(stmts: &Stmts) -> Self {
let mut trace = Trace {
tokens: BTreeMap::new(),
stmt_positions: vec![],
rule_tokens: vec![],
};
trace.flatten_stmts(stmts);
trace
}
fn flatten_stmts(&mut self, stmts: &Stmts) {
for (stmt_idx, stmt) in stmts.stmts.iter().enumerate() {
let mut last_level = None;
let start_path = Path {
position: vec![
Position::IdxWithFragment {
idx: stmt_idx,
fragment: stmt.lhs,
},
],
};
self.stmt_positions.push(StmtTokenPosition {
lhs: Some(stmt.lhs),
position: self.tokens.len()
});
for (alternative_idx, (level, ref rhs, ref _action)) in stmt.body.iter().enumerate() {
let mut path = start_path.clone();
if stmt.body.len() > 1 {
path.position.push(Position::Alternative(alternative_idx));
}
if alternative_idx != 0 {
let token = if last_level.is_none() || last_level == Some(level) {
TraceToken::Alternative
} else {
TraceToken::PrecedencedAlternative
};
self.tokens.insert(path.clone(), token);
}
last_level = Some(level);
self.flatten_rhs(path, rhs);
}
}
self.stmt_positions.push(StmtTokenPosition {
lhs: None,
position: self.tokens.len(),
});
}
fn flatten_rhs(&mut self, path: Path, rhs: &Rhs) {
for (rhs_idx, element) in rhs.0.iter().enumerate() {
let mut path = path.clone();
match &element.elem {
&RhsAst::Fragment(_) => {}
_ => {
if rhs.0.len() > 1 {
path.position.push(Position::Idx(rhs_idx));
}
}
}
match &element.elem {
&RhsAst::Fragment(fragment_id) => {
path.position.push(Position::IdxWithFragment {
idx: rhs_idx,
fragment: fragment_id,
});
self.tokens.insert(path, TraceToken::Fragment(fragment_id));
}
&RhsAst::String(ref _string) => {
unimplemented!()
}
&RhsAst::Sequence(ref sequence) => {
path.position.push(Position::Sequence {
min: sequence.min,
max: sequence.max,
});
if sequence.rhs.0.len() > 1 {
let left_paren_path = path.clone();
let mut right_paren_path = path.clone();
right_paren_path.position.push(Position::SequenceEnd);
self.tokens.insert(left_paren_path, TraceToken::LParen);
self.tokens.insert(right_paren_path, TraceToken::RParen);
}
let mut star_or_plus_path = path.clone();
star_or_plus_path.position.push(Position::SequenceToken);
if sequence.min == 0 && sequence.max == None {
self.tokens.insert(star_or_plus_path, TraceToken::Star);
} else if sequence.min == 1 && sequence.max == None {
self.tokens.insert(star_or_plus_path, TraceToken::Plus);
}
self.flatten_rhs(path, &sequence.rhs);
}
&RhsAst::Sum(ref summands) => {
if summands.is_empty() {
self.tokens.insert(path.clone(), TraceToken::EmptyProduct);
}
for (summand_idx, summand) in summands.iter().enumerate() {
let mut path = path.clone();
if summands.len() > 1 {
path.position.push(Position::Alternative(summand_idx));
}
if summand_idx != 0 {
self.tokens.insert(path.clone(), TraceToken::Alternative);
}
self.flatten_rhs(path, summand);
}
}
&RhsAst::Product(ref rhs) => {
let mut left_paren_path = path.clone();
let mut right_paren_path = path.clone();
left_paren_path.position.push(Position::Idx(0));
right_paren_path.position.push(Position::Idx(1));
self.tokens.insert(left_paren_path, TraceToken::LParen);
self.tokens.insert(right_paren_path, TraceToken::RParen);
self.flatten_rhs(path, rhs);
}
}
}
if rhs.0.is_empty() {
self.tokens.insert(path, TraceToken::EmptyProduct);
}
}
pub fn traces_for_path(&self, path: &Path) -> (usize, usize) {
let mut max_path = path.clone();
max_path.position.push(Position::Max);
(self.tokens.range(.. path).count(), self.tokens.range(.. max_path).count())
}
pub fn tokens(&self) -> &BTreeMap<Path, TraceToken> {
&self.tokens
}
pub fn stringify_tokens(&self, fragment_names: &BTreeMap<FragmentId, String>) -> Vec<String> {
self.tokens.iter().map(|(_, token)| {
token.as_str(fragment_names).to_string()
}).collect()
}
}