minidom/
tree_builder.rs

1// Copyright (c) 2022 Astro <astro@spaceboyz.net>
2
3//! SAX events to DOM tree conversion
4
5use crate::prefixes::{Prefix, Prefixes};
6use crate::{Element, Error};
7use alloc::collections::BTreeMap;
8use alloc::format;
9use alloc::string::String;
10use alloc::vec::Vec;
11use rxml::RawEvent;
12
13/// Tree-building parser state
14pub struct TreeBuilder {
15    next_tag: Option<(Prefix, String, Prefixes, BTreeMap<String, String>)>,
16    /// Parsing stack
17    stack: Vec<Element>,
18    /// Namespace set stack by prefix
19    prefixes_stack: Vec<Prefixes>,
20    /// Document root element if finished
21    pub root: Option<Element>,
22}
23
24impl Default for TreeBuilder {
25    fn default() -> Self {
26        Self::new()
27    }
28}
29
30impl TreeBuilder {
31    /// Create a new one
32    #[must_use]
33    pub fn new() -> Self {
34        TreeBuilder {
35            next_tag: None,
36            stack: Vec::new(),
37            prefixes_stack: Vec::new(),
38            root: None,
39        }
40    }
41
42    /// Allow setting prefixes stack.
43    ///
44    /// Useful to provide knowledge of namespaces that would have been declared on parent elements
45    /// not present in the reader.
46    #[must_use]
47    pub fn with_prefixes_stack(mut self, prefixes_stack: Vec<Prefixes>) -> Self {
48        self.prefixes_stack = prefixes_stack;
49        self
50    }
51
52    /// Stack depth
53    #[must_use]
54    pub fn depth(&self) -> usize {
55        self.stack.len()
56    }
57
58    /// Get the top-most element from the stack but don't remove it
59    #[must_use]
60    pub fn top(&mut self) -> Option<&Element> {
61        self.stack.last()
62    }
63
64    /// Pop the top-most element from the stack
65    fn pop(&mut self) -> Option<Element> {
66        self.prefixes_stack.pop();
67        self.stack.pop()
68    }
69
70    /// Unshift the first child of the top element
71    pub fn unshift_child(&mut self) -> Option<Element> {
72        let depth = self.stack.len();
73        if depth > 0 {
74            self.stack[depth - 1].unshift_child()
75        } else {
76            None
77        }
78    }
79
80    /// Lookup XML namespace declaration for given prefix (or no prefix)
81    #[must_use]
82    fn lookup_prefix(&self, prefix: &Option<String>) -> Option<&str> {
83        for nss in self.prefixes_stack.iter().rev() {
84            if let Some(ns) = nss.get(prefix) {
85                return Some(ns);
86            }
87        }
88
89        None
90    }
91
92    fn process_end_tag(&mut self) {
93        if let Some(el) = self.pop() {
94            if self.depth() > 0 {
95                let top = self.stack.len() - 1;
96                self.stack[top].append_child(el);
97            } else {
98                self.root = Some(el);
99            }
100        }
101    }
102
103    fn process_text(&mut self, text: String) {
104        if self.depth() > 0 {
105            let top = self.stack.len() - 1;
106            self.stack[top].append_text(text);
107        }
108    }
109
110    /// Process an event that you got out of a `RawParser`.
111    pub fn process_event(&mut self, event: RawEvent) -> Result<(), Error> {
112        match event {
113            RawEvent::XmlDeclaration(_, _) => {}
114
115            RawEvent::ElementHeadOpen(_, (prefix, name)) => {
116                // If self.prefixes_stack has been set via with_prefixes_stack before processing,
117                // ensure these are set on the root element.
118                let prefixes = if self.stack.is_empty() && self.prefixes_stack.len() == 1 {
119                    self.prefixes_stack.pop().unwrap()
120                } else {
121                    Prefixes::default()
122                };
123
124                self.next_tag = Some((
125                    prefix.map(|prefix| prefix.as_str().to_owned()),
126                    name.as_str().to_owned(),
127                    prefixes,
128                    BTreeMap::new(),
129                ));
130            }
131
132            RawEvent::Attribute(_, (prefix, name), value) => {
133                if let Some((_, _, ref mut prefixes, ref mut attrs)) = self.next_tag.as_mut() {
134                    match (prefix, name) {
135                        (None, xmlns) if xmlns == "xmlns" => prefixes.insert(None, value),
136                        (Some(xmlns), prefix) if xmlns.as_str() == "xmlns" => {
137                            prefixes.insert(Some(prefix.as_str().to_owned()), value);
138                        }
139                        (Some(prefix), name) => {
140                            attrs.insert(format!("{prefix}:{name}"), value.as_str().to_owned());
141                        }
142                        (None, name) => {
143                            attrs.insert(name.as_str().to_owned(), value.as_str().to_owned());
144                        }
145                    }
146                }
147            }
148
149            RawEvent::ElementHeadClose(_) => {
150                if let Some((prefix, name, prefixes, attrs)) = self.next_tag.take() {
151                    self.prefixes_stack.push(prefixes.clone());
152
153                    let namespace = self
154                        .lookup_prefix(&prefix.map(|prefix| prefix.as_str().to_owned()))
155                        .ok_or(Error::MissingNamespace)?
156                        .to_owned();
157                    let el = Element::new(name.to_owned(), namespace, prefixes, attrs, Vec::new());
158                    self.stack.push(el);
159                }
160            }
161
162            RawEvent::ElementFoot(_) => self.process_end_tag(),
163
164            RawEvent::Text(_, text) => self.process_text(text.as_str().to_owned()),
165        }
166
167        Ok(())
168    }
169}
minidom/tree_builder.rs

minidom/
tree_builder.rs
