handlebars/json/
path.rs

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1use std::iter::Peekable;
2
3use pest::iterators::Pair;
4use pest::Parser;
5
6use crate::error::RenderError;
7use crate::grammar::{HandlebarsParser, Rule};
8use crate::RenderErrorReason;
9
10#[derive(PartialEq, Eq, Clone, Debug)]
11#[non_exhaustive]
12pub enum PathSeg {
13    Named(String),
14    Ruled(Rule),
15}
16
17/// Represents the Json path in templates.
18///
19/// It can be either a local variable like `@first`, `../@index`,
20/// or a normal relative path like `a/b/c`.
21#[derive(PartialEq, Eq, Clone, Debug)]
22pub enum Path {
23    Relative((Vec<PathSeg>, String)),
24    Local((usize, String, String)),
25}
26
27impl Path {
28    pub(crate) fn new(raw: &str, segs: Vec<PathSeg>) -> Path {
29        if let Some((level, name)) = get_local_path_and_level(&segs) {
30            Path::Local((level, name, raw.to_owned()))
31        } else {
32            Path::Relative((segs, raw.to_owned()))
33        }
34    }
35
36    pub fn parse(raw: &str) -> Result<Path, RenderError> {
37        HandlebarsParser::parse(Rule::path, raw)
38            .map(|p| {
39                let parsed = p.flatten();
40                let segs = parse_json_path_from_iter(&mut parsed.peekable(), raw.len());
41                Ok(Path::new(raw, segs))
42            })
43            .map_err(|_| RenderErrorReason::InvalidJsonPath(raw.to_owned()))?
44    }
45
46    pub(crate) fn raw(&self) -> &str {
47        match self {
48            Path::Relative((_, ref raw)) => raw,
49            Path::Local((_, _, ref raw)) => raw,
50        }
51    }
52
53    pub(crate) fn current() -> Path {
54        Path::Relative((Vec::with_capacity(0), String::new()))
55    }
56
57    // for test only
58    pub(crate) fn with_named_paths(name_segs: &[&str]) -> Path {
59        let segs = name_segs
60            .iter()
61            .map(|n| PathSeg::Named((*n).to_string()))
62            .collect();
63        Path::Relative((segs, name_segs.join("/")))
64    }
65
66    // for test only
67    pub(crate) fn segs(&self) -> Option<&[PathSeg]> {
68        match self {
69            Path::Relative((segs, _)) => Some(segs),
70            _ => None,
71        }
72    }
73}
74
75fn get_local_path_and_level(paths: &[PathSeg]) -> Option<(usize, String)> {
76    paths.first().and_then(|seg| {
77        if seg == &PathSeg::Ruled(Rule::path_local) {
78            let mut level = 0;
79            while paths.get(level + 1)? == &PathSeg::Ruled(Rule::path_up) {
80                level += 1;
81            }
82            if let Some(PathSeg::Named(name)) = paths.get(level + 1) {
83                Some((level, name.clone()))
84            } else {
85                None
86            }
87        } else {
88            None
89        }
90    })
91}
92
93pub(crate) fn parse_json_path_from_iter<'a, I>(it: &mut Peekable<I>, limit: usize) -> Vec<PathSeg>
94where
95    I: Iterator<Item = Pair<'a, Rule>>,
96{
97    let mut path_stack = Vec::with_capacity(5);
98    while let Some(n) = it.peek() {
99        let span = n.as_span();
100        if span.end() > limit {
101            break;
102        }
103
104        match n.as_rule() {
105            Rule::path_root => {
106                path_stack.push(PathSeg::Ruled(Rule::path_root));
107            }
108            Rule::path_local => {
109                path_stack.push(PathSeg::Ruled(Rule::path_local));
110            }
111            Rule::path_up => {
112                path_stack.push(PathSeg::Ruled(Rule::path_up));
113            }
114            Rule::path_id | Rule::path_raw_id => {
115                let name = n.as_str();
116                if name != "this" {
117                    path_stack.push(PathSeg::Named(name.to_string()));
118                }
119            }
120            _ => {}
121        }
122
123        it.next();
124    }
125
126    path_stack
127}
128
129pub(crate) fn merge_json_path(path_stack: &mut Vec<String>, relative_path: &[PathSeg]) {
130    for seg in relative_path {
131        match seg {
132            PathSeg::Named(ref s) => {
133                path_stack.push(s.to_owned());
134            }
135            PathSeg::Ruled(Rule::path_root) => {}
136            PathSeg::Ruled(Rule::path_up) => {}
137            _ => {}
138        }
139    }
140}
handlebars/json/path.rs

handlebars/json/
path.rs
