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use pest::error::{Error, ErrorVariant};
use pest::iterators::{Pair, Pairs};
use pest::Parser as PestParser;
use pest::{RuleType, Span};
pub use pest_consume_macros::{make_parser, match_inputs};
static UNIT: () = ();
/// Carries a pest Pair alongside custom user data.
#[derive(Debug)]
pub struct ParseInput<'input, 'data, Rule: RuleType, Data> {
pair: Pair<'input, Rule>,
user_data: &'data Data,
}
/// Iterator over `ParseInput`s. It is created by `ParseInput::children` or `ParseInputs::new`.
#[derive(Debug)]
pub struct ParseInputs<'input, 'data, Rule: RuleType, Data> {
pairs: Pairs<'input, Rule>,
span: Span<'input>,
user_data: &'data Data,
}
impl<'i, 'd, R: RuleType, D> ParseInput<'i, 'd, R, D> {
pub fn new(pair: Pair<'i, R>, user_data: &'d D) -> Self {
ParseInput { pair, user_data }
}
/// Create an error that points to the span of the input.
pub fn error(&self, message: String) -> Error<R> {
Error::new_from_span(
ErrorVariant::CustomError { message },
self.as_span(),
)
}
/// Reconstruct the input with a new pair, passing the user data along.
pub fn with_pair(&self, new_pair: Pair<'i, R>) -> Self {
ParseInput {
pair: new_pair,
user_data: self.user_data,
}
}
/// If the contained pair has exactly one child, return a new Self containing it.
pub fn single_child(&self) -> Option<Self> {
let mut children = self.pair.clone().into_inner();
if let Some(child) = children.next() {
if children.next().is_none() {
return Some(self.with_pair(child));
}
}
None
}
/// Return an iterator over the children of this input
// Can't use `-> impl Iterator` because of weird lifetime limitations
// (see https://github.com/rust-lang/rust/issues/61997).
pub fn children(&self) -> ParseInputs<'i, 'd, R, D> {
ParseInputs {
pairs: self.as_pair().clone().into_inner(),
span: self.as_span(),
user_data: self.user_data(),
}
}
pub fn user_data(&self) -> &'d D {
self.user_data
}
pub fn as_pair(&self) -> &Pair<'i, R> {
&self.pair
}
pub fn as_span(&self) -> Span<'i> {
self.pair.as_span()
}
pub fn as_str(&self) -> &'i str {
self.pair.as_str()
}
pub fn as_rule(&self) -> R {
self.pair.as_rule()
}
pub fn as_rule_alias<C>(&self) -> String
where
C: PestConsumer<Rule = R>,
<C as PestConsumer>::Parser: PestParser<R>,
{
C::rule_alias(self.as_rule())
}
}
impl<'i, 'd, R: RuleType, D> ParseInputs<'i, 'd, R, D> {
/// `input` must be the _original_ input that `pairs` is pointing to.
pub fn new(input: &'i str, pairs: Pairs<'i, R>, user_data: &'d D) -> Self {
let span = Span::new(input, 0, input.len()).unwrap();
ParseInputs {
pairs,
span,
user_data,
}
}
/// Create an error that points to the span of the input.
pub fn error(&self, message: String) -> Error<R> {
Error::new_from_span(
ErrorVariant::CustomError { message },
self.span.clone(),
)
}
pub fn aliased_rules<C>(&self) -> Vec<String>
where
C: PestConsumer<Rule = R>,
<C as PestConsumer>::Parser: PestParser<R>,
{
self.clone().map(|p| p.as_rule_alias::<C>()).collect()
}
/// Reconstruct the input with a new pair, passing the user data along.
fn with_pair(&self, new_pair: Pair<'i, R>) -> ParseInput<'i, 'd, R, D> {
ParseInput::new(new_pair, self.user_data)
}
}
/// Used by the macros.
pub trait PestConsumer {
type Rule: RuleType;
type Parser: PestParser<Self::Rule>;
fn rule_alias(rule: Self::Rule) -> String;
fn allows_shortcut(rule: Self::Rule) -> bool;
fn parse_with_userdata<'i, 'd, D>(
rule: Self::Rule,
input_str: &'i str,
user_data: &'d D,
) -> Result<ParseInputs<'i, 'd, Self::Rule, D>, Error<Self::Rule>> {
let pairs = Self::Parser::parse(rule, input_str)?;
Ok(ParseInputs::new(input_str, pairs, user_data))
}
fn parse<'i>(
rule: Self::Rule,
input_str: &'i str,
) -> Result<ParseInputs<'i, 'static, Self::Rule, ()>, Error<Self::Rule>>
{
Self::parse_with_userdata(rule, input_str, &UNIT)
}
}
impl<'i, 'd, R: RuleType, D> Iterator for ParseInputs<'i, 'd, R, D> {
type Item = ParseInput<'i, 'd, R, D>;
fn next(&mut self) -> Option<Self::Item> {
let child_pair = self.pairs.next()?;
let child = self.with_pair(child_pair);
Some(child)
}
}
impl<'i, 'd, R: RuleType, D> DoubleEndedIterator for ParseInputs<'i, 'd, R, D> {
fn next_back(&mut self) -> Option<Self::Item> {
let child_pair = self.pairs.next_back()?;
let child = self.with_pair(child_pair);
Some(child)
}
}
// Manual impl to avoid stupid `D: Clone` trait bound
impl<'i, 'd, R: RuleType, D> Clone for ParseInput<'i, 'd, R, D> {
fn clone(&self) -> Self {
ParseInput {
pair: self.pair.clone(),
user_data: self.user_data,
}
}
}
// Manual impl to avoid stupid `D: Clone` trait bound
impl<'i, 'd, R: RuleType, D> Clone for ParseInputs<'i, 'd, R, D> {
fn clone(&self) -> Self {
ParseInputs {
pairs: self.pairs.clone(),
span: self.span.clone(),
user_data: self.user_data,
}
}
}
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