Parser

The parser reads file content, identifies comment lines using regex patterns, extracts TODO items, and captures surrounding context.

Parser

#![allow(unused)]
fn main() {
pub struct Parser {
    comment_patterns: Vec<Regex>,
    patterns: Vec<Pattern>,
    function_patterns: Vec<Regex>,
    context_lines: usize,
}
}

The parser is pub(crate) -- it is used internally by Scanner and not exposed in the public API. The public interface is through the module-level functions.

Construction

Created internally by Scanner::new() using Parser::new(config). All regex patterns are compiled once during construction.

Public Functions

validate_patterns

#![allow(unused)]
fn main() {
pub fn validate_patterns(config: &ParsingConfig) -> Result<(), TowlParserError>
}

Validates all regex patterns in the config without creating a parser. Useful for checking configuration before starting a scan.

Checks:

• Each pattern is valid regex
• Each pattern is within MAX_PATTERN_LENGTH (256 characters)
• Compiled regex is within REGEX_SIZE_LIMIT (256 KB)

parse_content

#![allow(unused)]
fn main() {
pub fn parse_content(
    config: &ParsingConfig,
    path: &Path,
    content: &str,
) -> Result<Vec<TodoComment>, TowlParserError>
}

Parses file content for TODO comments. Creates a temporary parser, runs extraction, and returns the results.

Parsing Pipeline

For each line in the file:

1. Comment detection -- Check if the line matches any comment_prefixes pattern
2. TODO matching -- Check if the comment matches any todo_patterns pattern
3. Type classification -- Determine the TodoType from the matched pattern
4. Description extraction -- Extract the description via the first capture group (.*)
5. Context capture -- Grab include_context_lines lines above and below
6. Function detection -- Search upward (within 3 lines) for a function_patterns match

Pattern Types

Comment Prefixes

Regex patterns that identify comment lines:

TODO Patterns

Regex patterns with a capture group for the description:

All default patterns are case-insensitive ((?i)).

Function Patterns

Regex patterns to detect enclosing function names:

Constants

Errors

#![allow(unused)]
fn main() {
pub enum TowlParserError {
    InvalidRegexPattern(String, regex::Error),
    UnknownConfigPattern(TowlCommentError),
    RegexGroupMissing,
    PatternTooLong(usize, usize),
    TooManyTotalPatterns { count: usize, max_allowed: usize },
}
}