Struct SourceView 

pub struct SourceView { /* private fields */ }

Efficient view into a JavaScript source string with lazy line indexing.

Stores the source as Arc<str> for cheap cloning. Line boundaries are computed on first access and cached with OnceLock for lock-free concurrent reads.

UTF-16 column support

JavaScript source maps use UTF-16 code-unit offsets for columns. Methods like get_line_slice accept UTF-16 columns and convert them to byte offsets internally.

Implementations

impl SourceView

pub fn new(source: Arc<str>) -> Self

Create a new SourceView from a shared source string.

pub fn from_string(source: String) -> Self

Create a new SourceView from an owned String.

pub fn source(&self) -> &str

Return the full source string.

pub fn line_count(&self) -> usize

Return the number of lines in the source.

A trailing newline does NOT produce an extra empty line (e.g. "a\n" has 1 line, "a\nb" has 2 lines).

pub fn get_line(&self, idx: u32) -> Option<&str>

Get a specific line by 0-based index.

Returns None if idx is out of bounds. The returned slice does NOT include the line terminator.

pub fn get_line_slice(&self, line: u32, col: u32, span: u32) -> Option<&str>

Get a substring of a line using UTF-16 column offsets.

line and col are 0-based. span is the number of UTF-16 code units to include. Returns None if the line index is out of bounds or the column/span extends past the line.

This is necessary because JavaScript source maps encode columns as UTF-16 code unit offsets, but Rust strings are UTF-8.

pub fn get_original_function_name<'a>( &self, token: &OriginalLocation, minified_name: &str, sm: &'a SourceMap, ) -> Option<&'a str>

Attempt to infer the original function name for a token.

This is a best-effort heuristic used for error grouping. Given a token’s position in the generated (minified) source and the minified name at that position, it looks at surrounding code patterns to identify the function context.

Algorithm

1. Find the mapping at the token’s generated position
2. Look backwards from that position in the generated line to find patterns like name(, name:, name =, .name
3. If the identified name matches minified_name, look it up in the source map for the original name

Trait Implementations

impl Clone for SourceView

fn clone(&self) -> SourceView

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SourceView

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.