ass_core/parser/streaming/delta/
parse_delta.rs

1//! Parse delta enum for streaming updates
2//!
3//! Defines [`ParseDelta`], the atomic change representation produced during
4//! incremental parsing along with its zero-copy constructors and inspectors.
5
6use crate::parser::ast::Section;
7use alloc::string::String;
8
9/// Delta operations for streaming updates
10///
11/// Represents atomic changes detected during incremental parsing.
12/// Used by editors and streaming applications to efficiently update
13/// internal state without full re-parsing.
14///
15/// # Performance
16///
17/// Deltas use zero-copy design where possible to minimize allocations.
18/// Section references point to parsed AST nodes using lifetime parameters.
19///
20/// # Example
21///
22/// ```rust
23/// use ass_core::parser::streaming::ParseDelta;
24///
25/// // Handle delta operations
26/// fn apply_deltas(deltas: Vec<ParseDelta>) {
27///     for delta in deltas {
28///         match delta {
29///             ParseDelta::AddSection(section) => {
30///                 // Add new section to document
31///             }
32///             ParseDelta::UpdateSection(index, section) => {
33///                 // Update existing section
34///             }
35///             ParseDelta::RemoveSection(index) => {
36///                 // Remove section at index
37///             }
38///             ParseDelta::ParseIssue(issue) => {
39///                 // Handle parsing error/warning
40///             }
41///         }
42///     }
43/// }
44/// ```
45#[derive(Debug, Clone)]
46pub enum ParseDelta<'a> {
47    /// Section was added to the script
48    ///
49    /// Contains the complete parsed section with zero-copy references
50    /// to source text spans.
51    AddSection(Section<'a>),
52
53    /// Section was modified during incremental parsing
54    ///
55    /// Contains the section index and updated section data. Consumers should replace
56    /// the existing section at the specified index with this new data.
57    UpdateSection(usize, Section<'a>),
58
59    /// Section was removed by index
60    ///
61    /// Contains the zero-based index of the section that should be
62    /// removed from the script.
63    RemoveSection(usize),
64
65    /// Parsing issue detected during processing
66    ///
67    /// Contains error or warning message about parsing problems.
68    /// Parsing may continue despite issues for error recovery.
69    ParseIssue(String),
70}
71
72impl<'a> ParseDelta<'a> {
73    /// Create delta for adding a section
74    #[must_use]
75    pub const fn add_section(section: Section<'a>) -> Self {
76        Self::AddSection(section)
77    }
78
79    /// Create delta for updating a section
80    #[must_use]
81    pub const fn update_section(index: usize, section: Section<'a>) -> Self {
82        Self::UpdateSection(index, section)
83    }
84
85    /// Create delta for removing a section by index
86    #[must_use]
87    pub const fn remove_section(index: usize) -> Self {
88        Self::RemoveSection(index)
89    }
90
91    /// Create delta for parsing issue
92    #[must_use]
93    pub const fn parse_issue(message: String) -> Self {
94        Self::ParseIssue(message)
95    }
96
97    /// Check if delta represents an error condition
98    #[must_use]
99    pub const fn is_error(&self) -> bool {
100        matches!(self, Self::ParseIssue(_))
101    }
102
103    /// Check if delta modifies document structure
104    #[must_use]
105    pub const fn is_structural(&self) -> bool {
106        matches!(
107            self,
108            Self::AddSection(_) | Self::UpdateSection(_, _) | Self::RemoveSection(_)
109        )
110    }
111
112    /// Get section reference if delta contains one
113    #[must_use]
114    pub const fn section(&self) -> Option<&Section<'a>> {
115        match self {
116            Self::AddSection(section) | Self::UpdateSection(_, section) => Some(section),
117            _ => None,
118        }
119    }
120}
ass_core/parser/streaming/delta/parse_delta.rs

ass_core/parser/streaming/delta/
parse_delta.rs
