1 unstable release
0.1.0 | Nov 26, 2023 |
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#16 in #pest-grammar
27KB
448 lines
pest_extra
pest_extra provides additional functionality for the Pest parser
Features
Grammar
See below to find how to compile this grammar into Pest grammar.
Variables
A variable is a string that you can use in rules:
variable = "value" // easier than variable = { "value" }
Including other grammar in grammar
Idea: https://github.com/pest-parser/pest/pull/759
Includes all the rules from one grammar to another.
Example
calculator.pest
include!("grammar2.pest")
integer = @{ ASCII_DIGIT+ }
primary = _{ integer | "(" ~ expr ~ ")" }
atom = _{ unary_minus? ~ primary }
expr = { atom ~ (bin_op ~ atom)* }
equation = _{ SOI ~ expr ~ EOI }
grammar2.pest
WHITESPACE = _{ " " }
unary_minus = { "-" }
bin_op = _{ add | subtract | multiply | divide | modulo }
add = { "+" }
subtract = { "-" }
multiply = { "*" }
divide = { "/" }
modulo = { "%" }
compiled.pest
unary_minus = { "-" }
divide = { "/" }
modulo = { "%" }
WHITESPACE = _{ " " }
equation = _{ SOI ~ expr ~ EOI }
bin_op = _{ add | subtract | multiply | divide | modulo }
atom = _{ unary_minus? ~ primary }
integer = @{ ASCII_DIGIT+ }
primary = _{ integer | "(" ~ expr ~ ")" }
add = { "+" }
expr = { atom ~ (bin_op ~ atom)* }
multiply = { "*" }
subtract = { "-" }
Other
Installation (for formatting and minifying):
[dependencies]
pest_extra = { version = "0.1.0", features = [ "formatter" ] }
Formatting
Uses pest-fmt.
Usage:
use pest_extra::formatter;
fn main() {
println!("{}", formatter::format(include_str!("./grammar.pest").to_string()));
}
Minifying
Minifies Pest grammar.
Usage:
use pest_extra::formatter;
fn main() {
println!("{}", formatter::minify(include_str!("./grammar.pest").to_string()));
}
Comparsion:
calculator.pest
Size: 556 bytes
// No whitespace allowed between digits
integer = @{ ASCII_DIGIT+ }
unary_minus = { "-" }
primary = _{ integer | "(" ~ expr ~ ")" }
atom = _{ unary_minus? ~ primary }
bin_op = _{ add | subtract | multiply | divide | modulo }
add = { "+" }
subtract = { "-" }
multiply = { "*" }
divide = { "/" }
modulo = { "%" }
expr = { atom ~ (bin_op ~ atom)* }
// We can't have SOI and EOI on expr directly, because it is used recursively (e.g. with parentheses)
equation = _{ SOI ~ expr ~ EOI }
WHITESPACE = _{ " " }
Size: 272 bytes (saved 48.92%)
minified-calculator.pest
integer=@{ASCII_DIGIT+}unary_minus={"-"}primary=_{integer|"("~expr~")"}atom=_{unary_minus?~primary}bin_op=_{add|subtract|multiply|divide|modulo}add={"+"}subtract={"-"}multiply={"*"}divide={"/"}modulo={"%"}expr={atom~(bin_op~atom)*}equation=_{SOI~expr~EOI}WHITESPACE=_{" "}
Compiling grammar into the Pest grammar
Installation
[dependencies]
pest_extra = "0.1.0"
Usage
use pest_extra::{
formatter,
parser::{compile_grammar, types::Grammar},
};
fn main() {
// Compiling grammar
if let Ok(grammar) = compile_grammar(Grammar::from_file("./grammar.pest").unwrap()) {
// Formatting grammar
println!("{}", formatter::format(grammar).unwrap());
}
}
Pest VM
pest_extra has built-in pest_vm to create a parser from your grammar.
Installation
[dependencies]
pest_extra = { version = "0.1.0", features = [ "vm" ] }
Usage
use pest_extra::{
parser::{compile_grammar, types::Grammar},
vm
};
fn main() {
// Compiling grammar
if let Ok(grammar) = compile_grammar(Grammar::from_file("./grammar.pest").unwrap()) {
// Creating parser
let vm = vm::PestVm::new(&grammar).vm;
let result = vm.parse("rule as &str", "input as &str");
}
}
License
MIT
Dependencies
~2–10MB
~111K SLoC