Struct Grammar

pub struct Grammar(/* private fields */);

A state machine that produces arbitrary matching expressions or byte sequences from Unstructured.

Implementation

Construction

Grammar is constructed using from_str of a string that specifies the syntax of expressions:

• A peg parser converts the string into an “intermediary representation” AST (in ir.rs).
• The IR is validated for duplicate and conflicting rule definitions
• The IR is converted to a state machine in which regex is parsed and rule definitions are indexed.

Expression Generation

Unstructured is used to generate arbitrary choices and loops to traverse the state machine. When a “leaf” state is reached, e.g. a pre-defined rule, regex, or string literal, Unstructured is used to write arbitrary data (except for string literals) to an output buffer.

Implementations

impl Grammar

pub fn expression<V: Visitor>( &self, u: &mut Unstructured<'_>, max_depth: Option<usize>, ) -> Result<V>

Returns a resulting Visitor after an arbitirary state machine traversal.

The state machine traversal starts at the first rule in the grammar.

Trait Implementations

impl Debug for Grammar

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

Formats the value using the given formatter.

impl Display for Grammar

Pretty prints the state machine.

It’s helpful to check if the compiled state machine matches what is expected from the the un-parsed grammar (the printed rules are more verbose and order of operations is clearer)

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

Formats the value using the given formatter.

impl FromStr for Grammar

type Err = Error

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type.

impl TryFrom<Vec<(String, Expr)>> for Grammar

type Error = Error

The type returned in the event of a conversion error.

fn try_from(value: Vec<(String, Expr)>) -> Result<Self, Self::Error>

Performs the conversion.