uqa-analysis 0.3.6

Tokenizers, char/token filters, and analyzers for UQA full-text search
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

//
// Unified Query Algebra
//
// Copyright (c) 2023-2026 Cognica, Inc.
//

//! Stemmer scratch and result buffers share the caller's allocation allowance.

use uqa_core::memory::{Budgeted, BudgetedString, BudgetedVec, MemoryBudget, MemoryError};

use super::{algorithm, word::Word, Character};
use crate::{AnalysisResult, TokenTerm};

pub fn stem(word: &str) -> String {
    stem_budgeted(word, &MemoryBudget::new(usize::MAX), || Ok(()))
        .expect("unbounded Porter stemming")
        .into_parts()
        .0
}

#[cfg(test)]
pub(crate) fn stem_utf16(word: &[u16]) -> Vec<u16> {
    stem_utf16_budgeted(word, &MemoryBudget::new(usize::MAX), &mut || Ok(()))
        .expect("unbounded lossless Porter stemming")
        .into_parts()
        .0
}

/// Stem scalar text with reserved scratch/output buffers and cancellation checks.
///
/// Input is borrowed. The result retains its string reservation; scratch is released before return. Character loading, prefix scans, suffix stages, and encoding poll for cancellation. Consonant state for repeated `y` is computed without recursion.
///
/// ```
/// use uqa_analysis::porter::stem_budgeted;
/// use uqa_core::memory::MemoryBudget;
/// let budget = MemoryBudget::new(4096);
/// let result = stem_budgeted("relational", &budget, || Ok(()))?;
/// assert_eq!(&**result, "relat");
/// assert_eq!(budget.used(), result.reserved_bytes());
/// assert!(budget.peak() > budget.used());
/// drop(result);
/// assert_eq!(budget.used(), 0);
/// # Ok::<(), uqa_analysis::AnalysisError>(())
/// ```
pub fn stem_budgeted(
    input: &str,
    budget: &MemoryBudget,
    mut poll: impl FnMut() -> AnalysisResult<()>,
) -> AnalysisResult<Budgeted<String>> {
    let mut word = Word::new(input.chars().map(Character::from), budget, &mut poll)?;
    algorithm::apply(&mut word)?;
    let mut length = 0usize;
    for index in 0..word.len() {
        if index % 1024 == 0 {
            word.check()?;
        }
        let character = char::from_u32(word[index].0).expect("scalar input and ASCII suffixes");
        length = length
            .checked_add(character.len_utf8())
            .ok_or(MemoryError::SizeOverflow)?;
    }
    let mut output = BudgetedString::new(budget);
    output.reserve(length)?;
    for index in 0..word.len() {
        if index % 1024 == 0 {
            word.check()?;
        }
        output.push(char::from_u32(word[index].0).expect("scalar input and ASCII suffixes"))?;
    }
    word.check()?;
    drop(word);
    let (output, memory) = output.into_parts();
    Ok(Budgeted::new(output, memory))
}

/// Stem a complete lossless term, including isolated surrogate elements.
pub fn stem_term_budgeted(
    input: &TokenTerm,
    budget: &MemoryBudget,
    mut poll: impl FnMut() -> AnalysisResult<()>,
) -> AnalysisResult<Budgeted<TokenTerm>> {
    if let Some(input) = input.as_str() {
        let (term, memory) = stem_budgeted(input, budget, poll)?.into_parts();
        Ok(Budgeted::new(term.into(), memory))
    } else {
        let output = stem_utf16_budgeted(&input.utf16(), budget, &mut poll)?;
        TokenTerm::from_utf16_budgeted(output, poll)
    }
}

pub(super) fn stem_utf16_budgeted(
    input: &[u16],
    budget: &MemoryBudget,
    poll: &mut dyn FnMut() -> AnalysisResult<()>,
) -> AnalysisResult<Budgeted<Vec<u16>>> {
    let characters = char::decode_utf16(input.iter().copied()).map(|value| {
        value.map_or_else(
            |error| Character(u32::from(error.unpaired_surrogate())),
            Character::from,
        )
    });
    let mut word = Word::new(characters, budget, poll)?;
    algorithm::apply(&mut word)?;
    let mut length = 0usize;
    for index in 0..word.len() {
        if index % 1024 == 0 {
            word.check()?;
        }
        let units = char::from_u32(word[index].0).map_or(1, char::len_utf16);
        length = length.checked_add(units).ok_or(MemoryError::SizeOverflow)?;
    }
    let mut output = BudgetedVec::new(budget);
    output.reserve(length)?;
    for index in 0..word.len() {
        if index % 1024 == 0 {
            word.check()?;
        }
        if let Some(character) = char::from_u32(word[index].0) {
            for unit in character.encode_utf16(&mut [0; 2]) {
                output.push(*unit)?;
            }
        } else {
            output.push(u16::try_from(word[index].0).expect("isolated surrogate"))?;
        }
    }
    word.check()?;
    drop(word);
    let (output, memory) = output.into_parts();
    Ok(Budgeted::new(output, memory))
}