minidom/
tree_builder.rs

1// Copyright (c) 2022 Astro <astro@spaceboyz.net>
2//
3// This Source Code Form is subject to the terms of the Mozilla Public
4// License, v. 2.0. If a copy of the MPL was not distributed with this
5// file, You can obtain one at http://mozilla.org/MPL/2.0/.
6
7//! SAX events to DOM tree conversion
8
9use crate::prefixes::{Prefix, Prefixes};
10use crate::{Element, Error};
11use alloc::collections::BTreeMap;
12use alloc::format;
13use alloc::string::String;
14use alloc::vec::Vec;
15use rxml::RawEvent;
16
17/// Tree-building parser state
18pub struct TreeBuilder {
19    next_tag: Option<(Prefix, String, Prefixes, BTreeMap<String, String>)>,
20    /// Parsing stack
21    stack: Vec<Element>,
22    /// Namespace set stack by prefix
23    prefixes_stack: Vec<Prefixes>,
24    /// Document root element if finished
25    pub root: Option<Element>,
26}
27
28impl Default for TreeBuilder {
29    fn default() -> Self {
30        Self::new()
31    }
32}
33
34impl TreeBuilder {
35    /// Create a new one
36    #[must_use]
37    pub fn new() -> Self {
38        TreeBuilder {
39            next_tag: None,
40            stack: Vec::new(),
41            prefixes_stack: Vec::new(),
42            root: None,
43        }
44    }
45
46    /// Allow setting prefixes stack.
47    ///
48    /// Useful to provide knowledge of namespaces that would have been declared on parent elements
49    /// not present in the reader.
50    #[must_use]
51    pub fn with_prefixes_stack(mut self, prefixes_stack: Vec<Prefixes>) -> Self {
52        self.prefixes_stack = prefixes_stack;
53        self
54    }
55
56    /// Stack depth
57    #[must_use]
58    pub fn depth(&self) -> usize {
59        self.stack.len()
60    }
61
62    /// Get the top-most element from the stack but don't remove it
63    #[must_use]
64    pub fn top(&mut self) -> Option<&Element> {
65        self.stack.last()
66    }
67
68    /// Pop the top-most element from the stack
69    fn pop(&mut self) -> Option<Element> {
70        self.prefixes_stack.pop();
71        self.stack.pop()
72    }
73
74    /// Unshift the first child of the top element
75    pub fn unshift_child(&mut self) -> Option<Element> {
76        let depth = self.stack.len();
77        if depth > 0 {
78            self.stack[depth - 1].unshift_child()
79        } else {
80            None
81        }
82    }
83
84    /// Lookup XML namespace declaration for given prefix (or no prefix)
85    #[must_use]
86    fn lookup_prefix(&self, prefix: &Option<String>) -> Option<&str> {
87        for nss in self.prefixes_stack.iter().rev() {
88            if let Some(ns) = nss.get(prefix) {
89                return Some(ns);
90            }
91        }
92
93        None
94    }
95
96    fn process_end_tag(&mut self) {
97        if let Some(el) = self.pop() {
98            if self.depth() > 0 {
99                let top = self.stack.len() - 1;
100                self.stack[top].append_child(el);
101            } else {
102                self.root = Some(el);
103            }
104        }
105    }
106
107    fn process_text(&mut self, text: String) {
108        if self.depth() > 0 {
109            let top = self.stack.len() - 1;
110            self.stack[top].append_text(text);
111        }
112    }
113
114    /// Process an event that you got out of a `RawParser`.
115    pub fn process_event(&mut self, event: RawEvent) -> Result<(), Error> {
116        match event {
117            RawEvent::XmlDeclaration(_, _) => {}
118
119            RawEvent::ElementHeadOpen(_, (prefix, name)) => {
120                // If self.prefixes_stack has been set via with_prefixes_stack before processing,
121                // ensure these are set on the root element.
122                let prefixes = if self.stack.is_empty() && self.prefixes_stack.len() == 1 {
123                    self.prefixes_stack.pop().unwrap()
124                } else {
125                    Prefixes::default()
126                };
127
128                self.next_tag = Some((
129                    prefix.map(|prefix| prefix.as_str().to_owned()),
130                    name.as_str().to_owned(),
131                    prefixes,
132                    BTreeMap::new(),
133                ));
134            }
135
136            RawEvent::Attribute(_, (prefix, name), value) => {
137                if let Some((_, _, ref mut prefixes, ref mut attrs)) = self.next_tag.as_mut() {
138                    match (prefix, name) {
139                        (None, xmlns) if xmlns == "xmlns" => prefixes.insert(None, value),
140                        (Some(xmlns), prefix) if xmlns.as_str() == "xmlns" => {
141                            prefixes.insert(Some(prefix.as_str().to_owned()), value);
142                        }
143                        (Some(prefix), name) => {
144                            attrs.insert(format!("{prefix}:{name}"), value.as_str().to_owned());
145                        }
146                        (None, name) => {
147                            attrs.insert(name.as_str().to_owned(), value.as_str().to_owned());
148                        }
149                    }
150                }
151            }
152
153            RawEvent::ElementHeadClose(_) => {
154                if let Some((prefix, name, prefixes, attrs)) = self.next_tag.take() {
155                    self.prefixes_stack.push(prefixes.clone());
156
157                    let namespace = self
158                        .lookup_prefix(&prefix.map(|prefix| prefix.as_str().to_owned()))
159                        .ok_or(Error::MissingNamespace)?
160                        .to_owned();
161                    let el = Element::new(name.to_owned(), namespace, prefixes, attrs, Vec::new());
162                    self.stack.push(el);
163                }
164            }
165
166            RawEvent::ElementFoot(_) => self.process_end_tag(),
167
168            RawEvent::Text(_, text) => self.process_text(text.as_str().to_owned()),
169        }
170
171        Ok(())
172    }
173}
minidom/tree_builder.rs

minidom/
tree_builder.rs
