use std::iter::Peekable; use pest::iterators::Pair; use pest::Parser; use crate::error::RenderError; use crate::grammar::{HandlebarsParser, Rule}; #[derive(PartialEq, Eq, Clone, Debug)] pub enum PathSeg { Named(String), Ruled(Rule), } /// Represents the Json path in templates. /// /// It can be either a local variable like `@first`, `../@index`, /// or a normal relative path like `a/b/c`. #[derive(PartialEq, Eq, Clone, Debug)] pub enum Path { Relative((Vec, String)), Local((usize, String, String)), } impl Path { pub(crate) fn new(raw: &str, segs: Vec) -> Path { if let Some((level, name)) = get_local_path_and_level(&segs) { Path::Local((level, name, raw.to_owned())) } else { Path::Relative((segs, raw.to_owned())) } } pub fn parse(raw: &str) -> Result { HandlebarsParser::parse(Rule::path, raw) .map(|p| { let parsed = p.flatten(); let segs = parse_json_path_from_iter(&mut parsed.peekable(), raw.len()); Ok(Path::new(raw, segs)) }) .map_err(|_| RenderError::new("Invalid JSON path"))? } pub(crate) fn raw(&self) -> &str { match self { Path::Relative((_, ref raw)) => raw, Path::Local((_, _, ref raw)) => raw, } } pub(crate) fn current() -> Path { Path::Relative((Vec::with_capacity(0), "".to_owned())) } // for test only pub(crate) fn with_named_paths(name_segs: &[&str]) -> Path { let segs = name_segs .iter() .map(|n| PathSeg::Named((*n).to_string())) .collect(); Path::Relative((segs, name_segs.join("/"))) } // for test only pub(crate) fn segs(&self) -> Option<&[PathSeg]> { match self { Path::Relative((segs, _)) => Some(segs), _ => None, } } } fn get_local_path_and_level(paths: &[PathSeg]) -> Option<(usize, String)> { paths.get(0).and_then(|seg| { if seg == &PathSeg::Ruled(Rule::path_local) { let mut level = 0; while paths.get(level + 1)? == &PathSeg::Ruled(Rule::path_up) { level += 1; } if let Some(PathSeg::Named(name)) = paths.get(level + 1) { Some((level, name.clone())) } else { None } } else { None } }) } pub(crate) fn parse_json_path_from_iter<'a, I>(it: &mut Peekable, limit: usize) -> Vec where I: Iterator>, { let mut path_stack = Vec::with_capacity(5); while let Some(n) = it.peek() { let span = n.as_span(); if span.end() > limit { break; } match n.as_rule() { Rule::path_root => { path_stack.push(PathSeg::Ruled(Rule::path_root)); } Rule::path_local => { path_stack.push(PathSeg::Ruled(Rule::path_local)); } Rule::path_up => { path_stack.push(PathSeg::Ruled(Rule::path_up)); } Rule::path_id | Rule::path_raw_id => { let name = n.as_str(); if name != "this" { path_stack.push(PathSeg::Named(name.to_string())); } } _ => {} } it.next(); } path_stack } pub(crate) fn merge_json_path(path_stack: &mut Vec, relative_path: &[PathSeg]) { for seg in relative_path { match seg { PathSeg::Named(ref s) => { path_stack.push(s.to_owned()); } PathSeg::Ruled(Rule::path_root) => {} PathSeg::Ruled(Rule::path_up) => {} _ => {} } } }