relay_event_schema/processor/chunks.rs
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//! Utilities for dealing with annotated strings.
//!
//! This module contains the `split` and `join` function to destructure and recombine strings by
//! redaction remarks. This allows to quickly inspect modified sections of a string.
//!
//! ### Example
//!
//! ```
//! use relay_event_schema::processor;
//! use relay_protocol::{Meta, Remark, RemarkType};
//!
//! let remarks = vec![Remark::with_range(
//! RemarkType::Substituted,
//! "myrule",
//! (7, 17),
//! )];
//!
//! let chunks = processor::split_chunks("Hello, [redacted]!", &remarks);
//! let (joined, join_remarks) = processor::join_chunks(chunks);
//!
//! assert_eq!(joined, "Hello, [redacted]!");
//! assert_eq!(join_remarks, remarks);
//! ```
use std::borrow::Cow;
use std::fmt;
use relay_protocol::{Meta, Remark, RemarkType};
use serde::{Deserialize, Serialize};
/// A type for dealing with chunks of annotated text.
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
#[serde(tag = "type", rename_all = "lowercase")]
pub enum Chunk<'a> {
/// Unmodified text chunk.
Text {
/// The text value of the chunk
text: Cow<'a, str>,
},
/// Redacted text chunk with a note.
Redaction {
/// The redacted text value
text: Cow<'a, str>,
/// The rule that crated this redaction
rule_id: Cow<'a, str>,
/// Type type of remark for this redaction
#[serde(rename = "remark")]
ty: RemarkType,
},
}
impl Chunk<'_> {
/// The text of this chunk.
pub fn as_str(&self) -> &str {
match self {
Chunk::Text { text } => text,
Chunk::Redaction { text, .. } => text,
}
}
/// Effective length of the text in this chunk.
pub fn len(&self) -> usize {
self.as_str().len()
}
/// The number of UTF-8 encoded Unicode codepoints in this chunk.
pub fn count(&self) -> usize {
bytecount::num_chars(self.as_str().as_bytes())
}
/// Determines whether this chunk is empty.
pub fn is_empty(&self) -> bool {
self.len() == 0
}
}
impl fmt::Display for Chunk<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", self.as_str())
}
}
/// Chunks the given text based on remarks.
pub fn split_chunks<'a, I>(text: &'a str, remarks: I) -> Vec<Chunk<'a>>
where
I: IntoIterator<Item = &'a Remark>,
{
let mut rv = vec![];
let mut pos = 0;
for remark in remarks {
let (from, to) = match remark.range() {
Some(range) => *range,
None => continue,
};
if from > pos {
if let Some(piece) = text.get(pos..from) {
rv.push(Chunk::Text {
text: Cow::Borrowed(piece),
});
} else {
break;
}
}
if let Some(piece) = text.get(from..to) {
rv.push(Chunk::Redaction {
text: Cow::Borrowed(piece),
rule_id: remark.rule_id().into(),
ty: remark.ty(),
});
} else {
break;
}
pos = to;
}
if pos < text.len() {
if let Some(piece) = text.get(pos..) {
rv.push(Chunk::Text {
text: Cow::Borrowed(piece),
});
}
}
rv
}
/// Concatenates chunks into a string and emits remarks for redacted sections.
pub fn join_chunks<'a, I>(chunks: I) -> (String, Vec<Remark>)
where
I: IntoIterator<Item = Chunk<'a>>,
{
let mut rv = String::new();
let mut remarks = vec![];
let mut pos = 0;
for chunk in chunks {
let new_pos = pos + chunk.len();
rv.push_str(chunk.as_str());
match chunk {
Chunk::Redaction { rule_id, ty, .. } => {
remarks.push(Remark::with_range(ty, rule_id.clone(), (pos, new_pos)))
}
Chunk::Text { .. } => {
// Plain text segments do not need remarks
}
}
pos = new_pos;
}
(rv, remarks)
}
/// Splits the string into chunks, maps each chunk and then joins chunks again, emitting
/// remarks along the process.
pub fn process_chunked_value<F>(value: &mut String, meta: &mut Meta, f: F)
where
F: FnOnce(Vec<Chunk>) -> Vec<Chunk>,
{
let chunks = split_chunks(value, meta.iter_remarks());
let (new_value, remarks) = join_chunks(f(chunks));
if new_value != *value {
meta.clear_remarks();
for remark in remarks.into_iter() {
meta.add_remark(remark);
}
meta.set_original_length(Some(bytecount::num_chars(value.as_bytes())));
*value = new_value;
}
}
#[cfg(test)]
mod tests {
use similar_asserts::assert_eq;
use super::*;
#[test]
fn test_chunk_split() {
let remarks = vec![Remark::with_range(
RemarkType::Masked,
"@email:strip",
(33, 47),
)];
let text = "Hello Peter, my email address is ****@*****.com. See you";
let chunks = vec![
Chunk::Text {
text: "Hello Peter, my email address is ".into(),
},
Chunk::Redaction {
ty: RemarkType::Masked,
text: "****@*****.com".into(),
rule_id: "@email:strip".into(),
},
Chunk::Text {
text: ". See you".into(),
},
];
assert_eq!(split_chunks(text, &remarks), chunks);
assert_eq!(join_chunks(chunks), (text.into(), remarks));
}
}