Struct Indenter 

pub struct Indenter {
    pub nl_type: String,
    pub open_paren_types: Vec<String>,
    pub close_paren_types: Vec<String>,
    pub indent_type: String,
    pub dedent_type: String,
    pub tab_len: usize,
}

Lark’s Indenter, configured by terminal names.

State machine per token: an NL at paren_level == 0 emits NL then INDENT/DEDENTs by comparing the post-newline whitespace width (count(' ') + count('\t') * tab_len, code points) against the indent stack; open/close types track paren_level; EOF flushes remaining DEDENTs.

Confirmed-and-kept deviations from indenter.py, all reviewer calls:

• A newline-free NL token yields an empty indent (Lark IndexErrors, after already yielding the NL).
• Paren underflow is left to the parser (Lark hard-asserts; its assert also vanishes under python -O).
• An unknown nl/indent/dedent NAME is a PostlexError at Postlex::session; Lark runs on, emitting a token of a type the grammar never declared.
• tab_len == 0 is a PostlexError at session time, where Lark asserts at Indenter() construction.
• nl/indent/dedent are matched and emitted by id, so if two terminals share a name only the first is recognized. Lark compares name strings, so both are. The paren types, which are only ever matched, do follow Lark and mark every matching id (a_duplicated_name_resolves_first_but_marks_every_paren_id). Unreachable through the compiler, which interns names.

Not a deviation: Lark’s closing assert self.indent_level == [0] (indenter.py:76) has no counterpart here because it cannot fail — the stack’s bottom is invariantly 0 and the pop loop stops there.

Fields

nl_type: String

open_paren_types: Vec<String>

close_paren_types: Vec<String>

indent_type: String

dedent_type: String

tab_len: usize

Trait Implementations

impl Clone for Indenter

fn clone(&self) -> Indenter

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Indenter

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

Formats the value using the given formatter.

impl Postlex for Indenter

fn session( &self, names: &[String], ) -> Result<Box<dyn PostlexStream>, PostlexError>

Start a session for one lex pass. names is the terminal-name table indexed by TokenId (the session resolves its configured names once). An unknown nl/indent/dedent name is a PostlexError (they are emitted or consumed, so they must exist); unknown paren names are dropped — Lark treats the paren types as matched-only string sets (Lark parity).

fn always_accept(&self) -> Vec<String>

Terminal names accepted in every parser state (indenter: [NL_type]).