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use super::types::Rule;
use crate::peg::grammar::Peg;
use crate::peg::parsing::{ErrorKind, ParseError, ParseNode, ParseResult, Span};
use log::debug;
impl Rule {
pub fn parse(&self, peg: &Peg, input: &str, position: usize, depth: usize) -> ParseResult {
match self {
Rule::Empty => ParseResult(1, position, Ok(vec![])),
Rule::Any => {
if position < input.len() {
ParseResult(
1,
position + 1,
Ok(vec![ParseNode::Terminal(Span(position, position + 1))]),
)
} else {
ParseResult(
1,
position,
Err(ParseError {
position,
expression: self.clone(),
error: ErrorKind::UnexpectedEndOfInput,
cause: None,
}),
)
}
}
Rule::Literal(pattern) => {
if input[position..].starts_with(pattern) {
ParseResult(
1,
position + pattern.len(),
Ok(vec![ParseNode::Terminal(Span(
position,
position + pattern.len(),
))]),
)
} else {
ParseResult(
1,
position,
Err(ParseError {
position,
expression: self.clone(),
error: ErrorKind::ExpressionDoesNotMatch,
cause: None,
}),
)
}
}
Rule::NonTerminal(name) => {
debug!("{}parsing {name} @ {position}", "│".repeat(depth));
let output =
match peg
.rules
.get(name)
.unwrap()
.parse(peg, input, position, depth + 1)
{
ParseResult(cost, new_pos, Ok(matches)) => ParseResult(
cost,
new_pos,
Ok(vec![ParseNode::NonTerminal(
name.clone(),
Span(position, new_pos),
matches,
)]),
),
ParseResult(cost, _, Err(inner)) => ParseResult(
cost,
position,
Err(ParseError {
position,
expression: self.clone(),
error: ErrorKind::NonTerminalDoesNotMatch,
cause: Some(Box::from(inner)),
}),
),
};
debug!(
"{}└{} {} @ {} -> {}",
"│".repeat(depth),
if output.2.is_ok() { "ok" } else { "err" },
name,
position,
output.1
);
output
}
Rule::Choice(choices) => {
for choice in choices {
if let ParseResult(cost, new_pos, Ok(matches)) =
choice.parse(peg, input, position, depth)
{
return ParseResult(cost, new_pos, Ok(matches));
}
}
ParseResult(
1,
position,
Err(ParseError {
position,
expression: self.clone(),
error: ErrorKind::ExpressionDoesNotMatch,
cause: None,
}),
)
}
Rule::Sequence(sequence) => {
let mut captures = vec![];
let mut pos = position;
for expr in sequence {
match expr.parse(peg, input, pos, depth) {
ParseResult(_, p, Ok(mut m)) => {
pos = p;
captures.append(&mut m);
}
ParseResult(_, _, Err(e)) => return ParseResult(1, position, Err(e)),
}
}
ParseResult(1, pos, Ok(captures))
}
Rule::ZeroOrMore(expr) => {
let mut captures = vec![];
let mut pos = position;
while let ParseResult(_, p, Ok(mut m)) = expr.parse(peg, input, pos, depth) {
pos = p;
captures.append(&mut m);
}
ParseResult(1, pos, Ok(captures))
}
Rule::OneOrMore(expr) => Rule::Sequence(vec![
Rule::Group(expr.clone()),
Rule::ZeroOrMore(expr.clone()),
])
.parse(peg, input, position, depth),
Rule::Optional(expr) => match expr.parse(peg, input, position, depth) {
ParseResult(_, pos, Ok(matches)) => ParseResult(1, pos, Ok(matches)),
ParseResult(_, _, Err(_)) => ParseResult(1, position, Ok(vec![])),
},
Rule::And(expr) => match expr.parse(peg, input, position, depth) {
ParseResult(_, _, Ok(_)) => ParseResult(1, position, Ok(vec![])),
ParseResult(_, _, Err(e)) => ParseResult(1, position, Err(e)),
},
Rule::Not(expr) => match expr.parse(peg, input, position, depth) {
ParseResult(_, _, Ok(m)) => ParseResult(
1,
position,
Err(ParseError {
position,
expression: self.clone(),
error: ErrorKind::NotDidMatch(m),
cause: None,
}),
),
ParseResult(_, _, Err(_)) => ParseResult(1, position, Ok(vec![])),
},
Rule::Group(expr) => expr.parse(peg, input, position, depth),
Rule::Range(start, end) => {
if position < input.len() {
let c = input[position..].chars().next().unwrap();
if start.chars().next().unwrap() <= c && c <= end.chars().next().unwrap() {
ParseResult(
1,
position + 1,
Ok(vec![ParseNode::Terminal(Span(position, position + 1))]),
)
} else {
ParseResult(
1,
position,
Err(ParseError {
position,
expression: self.clone(),
error: ErrorKind::ExpressionDoesNotMatch,
cause: None,
}),
)
}
} else {
ParseResult(
1,
position,
Err(ParseError {
position,
expression: self.clone(),
error: ErrorKind::ExpressionDoesNotMatch,
cause: None,
}),
)
}
}
Rule::Class(symbols) => {
if let Some(symbol) = symbols
.iter()
.find(|s| input[position..].starts_with(s.as_str()))
{
ParseResult(
1,
position + symbol.len(),
Ok(vec![ParseNode::Terminal(Span(
position,
position + symbol.len(),
))]),
)
} else {
ParseResult(
1,
position,
Err(ParseError {
position,
expression: self.clone(),
error: ErrorKind::ExpressionDoesNotMatch,
cause: None,
}),
)
}
}
}
}
}