jsondata 0.8.1

JSON processing package for document databases
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136

// Copyright © 2019 R Pratap Chakravarthy. All rights reserved.

//! Module jptr implements [JSON Pointer RFC spec.].
//!
//! [JSON Pointer RFC spec.]: https://tools.ietf.org/html/rfc6901

use crate::{json::Json, ops, Error, Result};

/// quote path fragment using backslash escape and tilde escape defined by the
/// RFC specification.
///
/// After escaping each path-fragment caller can join them with '/'.
pub fn quote(fragment: &str) -> String {
    let mut outs = String::new();
    for ch in fragment.chars() {
        match ch {
            // backslash escape
            '"' | '\\' | '\x00'..='\x1f' => {
                outs.push('\\');
                outs.push(ch)
            }
            // tilde escape
            '~' => {
                outs.push('~');
                outs.push('0')
            }
            '/' => {
                outs.push('~');
                outs.push('1')
            }
            _ => outs.push(ch),
        }
    }
    outs
}

/// unquote path fragment for backslash and tilde escape defined by the
/// RFC specification.
///
/// After un-escaping each path-fragment caller can join them with '/'.
pub fn unquote(fragment: &str) -> Result<String> {
    let mut outs = String::new();
    let (mut escaped, mut tilde) = (false, false);
    for ch in fragment.chars() {
        if escaped {
            escaped = false;
            outs.push(ch);
            continue;
        } else if tilde {
            tilde = false;
            match ch {
                '0' => outs.push('~'),
                '1' => outs.push('/'),
                _ => err_at!(JptrFail, msg: "invalid ~{}", ch)?,
            }
            continue;
        }

        match ch {
            '\\' => escaped = true, // backslash escape
            '~' => tilde = true,    // tilde escape
            _ => outs.push(ch),
        }
    }
    Ok(outs)
}

pub(crate) fn fragments(path: &str) -> Result<(Vec<String>, String)> {
    let mut frags: Vec<String> = vec![];
    let mut frag = String::new();
    let mut state: (bool, bool) = (false, false); // (escaped, tilde)
    for ch in path.chars() {
        state = match ch {
            ch if state.0 => {
                frag.push(ch);
                (false, state.1)
            }
            '0' if state.1 => {
                frag.push('~');
                (state.0, false)
            }
            '1' if state.1 => {
                frag.push('/');
                (state.0, false)
            }
            ch if state.1 => err_at!(JptrFail, msg: "invalid ~{}", ch)?,
            '/' => {
                frags.push(frag.clone());
                frag.truncate(0);
                (state.0, state.1)
            }
            '\\' => (true, state.1),
            '~' => (state.0, true),
            ch => {
                frag.push(ch);
                (state.0, state.1)
            }
        };
    }
    Ok((frags, frag))
}

pub(crate) fn lookup_mut<'a>(
    mut json: &'a mut Json,
    path: &str,
) -> Result<(&'a mut Json, String)> {
    let (frags, key) = fragments(path)?;
    for frag in frags {
        json = ops::index_mut(json, frag.as_str())?
    }
    Ok((json, key))
}

pub(crate) fn lookup_ref<'a>(
    mut json_doc: &'a Json,
    path: &str,
) -> Result<(&'a Json, String)> {
    let (frags, key) = fragments(path)?;
    for frag in frags {
        json_doc = json_doc[frag.as_str()].to_result()?;
    }
    Ok((json_doc, key))
}

pub(crate) fn fix_prefix(path: &str) -> Result<&str> {
    let mut chars = path.chars();
    if chars.next().unwrap() == '/' {
        Ok(chars.as_str())
    } else {
        err_at!(JptrFail, msg: "pointer should start with forward solidus")
    }
}

#[cfg(test)]
#[path = "jptr_test.rs"]
mod jptr_test;