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|
use pest::error::{Error, ErrorVariant};
use pest::iterators::Pair;
use pest::Span;
pub use pest_consume_macros::{make_parser, match_inputs};
/// Carries a pest Pair alongside custom user data.
#[derive(Debug)]
pub struct ParseInput<'input, 'data, Rule, Data>
where
Rule: pest::RuleType,
{
pair: Pair<'input, Rule>,
user_data: &'data Data,
}
/// Iterator over `ParseInput`s. It is created by `ParseInput::children`.
#[derive(Debug)]
pub struct ParseInputs<'input, 'data, Rule, Data>
where
Rule: pest::RuleType,
{
input: ParseInput<'input, 'data, Rule, Data>,
pairs: pest::iterators::Pairs<'input, Rule>,
}
impl<'input, 'data, Rule, Data> ParseInput<'input, 'data, Rule, Data>
where
Rule: pest::RuleType,
{
pub fn new(pair: Pair<'input, Rule>, user_data: &'data Data) -> Self {
ParseInput { pair, user_data }
}
/// Create an error that points to the span of the input.
pub fn error(&self, message: String) -> Error<Rule> {
let message = format!(
"{} while matching on:\n{}",
message,
debug_pair(self.pair.clone())
);
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<'input, Rule>) -> 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<'input, 'data, Rule, Data> {
ParseInputs {
input: self.clone(),
pairs: self.as_pair().clone().into_inner(),
}
}
pub fn user_data(&self) -> &'data Data {
self.user_data
}
pub fn as_pair(&self) -> &Pair<'input, Rule> {
&self.pair
}
pub fn as_span(&self) -> Span<'input> {
self.pair.as_span()
}
pub fn as_str(&self) -> &'input str {
self.pair.as_str()
}
pub fn as_rule(&self) -> Rule {
self.pair.as_rule()
}
pub fn as_rule_alias<T>(&self) -> String
where
T: PestConsumer<Rule = Rule>,
{
T::rule_alias(self.as_rule())
}
}
impl<'input, 'data, Rule, Data> ParseInputs<'input, 'data, Rule, Data>
where
Rule: pest::RuleType,
{
/// Create an error that points to the span of the input.
pub fn error(&self, message: String) -> Error<Rule> {
self.input.error(message)
}
pub fn aliased_rules<T>(&self) -> Vec<String>
where
T: PestConsumer<Rule = Rule>,
{
self.clone().map(|p| p.as_rule_alias::<T>()).collect()
}
}
/// Used by the macros.
pub trait PestConsumer {
type Rule: pest::RuleType;
fn rule_alias(rule: Self::Rule) -> String;
fn allows_shortcut(rule: Self::Rule) -> bool;
}
/// Pretty-print a pair and its nested children.
fn debug_pair<Rule: pest::RuleType>(pair: Pair<Rule>) -> String {
use std::fmt::Write;
let mut s = String::new();
fn aux<Rule: pest::RuleType>(
s: &mut String,
indent: usize,
prefix: String,
pair: Pair<Rule>,
) {
let indent_str = "| ".repeat(indent);
let rule = pair.as_rule();
let contents = pair.as_str();
let mut inner = pair.into_inner();
let mut first = true;
while let Some(p) = inner.next() {
if first {
first = false;
let last = inner.peek().is_none();
if last && p.as_str() == contents {
let prefix = format!("{}{:?} > ", prefix, rule);
aux(s, indent, prefix, p);
continue;
} else {
writeln!(
s,
r#"{}{}{:?}: "{}""#,
indent_str, prefix, rule, contents
)
.unwrap();
}
}
aux(s, indent + 1, "".into(), p);
}
if first {
writeln!(
s,
r#"{}{}{:?}: "{}""#,
indent_str, prefix, rule, contents
)
.unwrap();
}
}
aux(&mut s, 0, "".into(), pair);
s
}
impl<'input, 'data, Rule, Data> Iterator
for ParseInputs<'input, 'data, Rule, Data>
where
Rule: pest::RuleType,
{
type Item = ParseInput<'input, 'data, Rule, Data>;
fn next(&mut self) -> Option<Self::Item> {
let child_pair = self.pairs.next()?;
let child = self.input.with_pair(child_pair);
Some(child)
}
}
impl<'input, 'data, Rule, Data> DoubleEndedIterator
for ParseInputs<'input, 'data, Rule, Data>
where
Rule: pest::RuleType,
{
fn next_back(&mut self) -> Option<Self::Item> {
let child_pair = self.pairs.next_back()?;
let child = self.input.with_pair(child_pair);
Some(child)
}
}
// Manual impl to avoid stupid `Data: Clone` trait bound
impl<'input, 'data, Rule, Data> Clone for ParseInput<'input, 'data, Rule, Data>
where
Rule: pest::RuleType,
{
fn clone(&self) -> Self {
ParseInput {
pair: self.pair.clone(),
user_data: self.user_data,
}
}
}
// Manual impl to avoid stupid `Data: Clone` trait bound
impl<'input, 'data, Rule, Data> Clone for ParseInputs<'input, 'data, Rule, Data>
where
Rule: pest::RuleType,
{
fn clone(&self) -> Self {
ParseInputs {
input: self.input.clone(),
pairs: self.pairs.clone(),
}
}
}
|
