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use super::lparser::Rule;
use std::rc::Rc;
pub fn from_parse_tree(parse_tree: &mut pest::iterators::Pairs<Rule>) -> Program {
let root = parse_tree.next().unwrap();
match root.as_rule() {
Rule::program => {
let statements_with_eoi: Vec<pest::iterators::Pair<Rule>> = root.into_inner().collect();
let statements_split = statements_with_eoi.split_last().unwrap();
let statements = statements_split.1.to_vec();
statements
.iter()
.map(|s| Statement::from_pair(s.clone()))
.collect()
}
_ => panic!("[ast] first Pair is not a program"),
}
}
pub type Program = Vec<Statement>;
#[derive(Debug)]
pub enum Statement {
Definition {
symbol: Symbol,
parameters: Vec<Symbol>,
expression: Rc<Expression>,
},
Expression(Rc<Expression>),
}
impl Statement {
fn from_pair(pair: pest::iterators::Pair<Rule>) -> Statement {
let def_or_expr = pair.into_inner().next().unwrap();
fn definition_from_pair(pair: pest::iterators::Pair<Rule>) -> Statement {
let mut inner = pair.into_inner();
let symbol = inner.next().unwrap().as_span().as_str();
let mut parameters: Vec<Symbol> = vec![];
let mut expression_opt: Option<Rc<Expression>> = None;
for p in inner {
match p.as_rule() {
Rule::symbol => parameters.push(p.as_span().as_str().to_owned()),
Rule::expression => {
let expression_inners: Vec<ExpressionInner> =
p.into_inner().map(ExpressionInner::from_pair).collect();
expression_opt = Some(expression_vec_to_tuple(&expression_inners));
}
_ => panic!(
"[ast] illegal rule {:#?} as child of definition",
p.as_rule()
),
}
}
let expression =
expression_opt.expect("[ast] no expression found as child of definition");
Statement::Definition {
symbol: symbol.to_owned(),
parameters,
expression,
}
}
match def_or_expr.as_rule() {
Rule::definition => definition_from_pair(def_or_expr),
Rule::expression => {
let expression_inners: Vec<ExpressionInner> = def_or_expr
.into_inner()
.map(ExpressionInner::from_pair)
.collect();
Statement::Expression(expression_vec_to_tuple(&expression_inners))
}
rule => panic!("[ast] can't make a statement from {:#?}", rule),
}
}
}
#[derive(Debug, Clone)]
pub enum ExpressionInner {
Symbol(Symbol),
IntegerLiteral(IntegerLiteral),
StringLiteral(StringLiteral),
Expression(Rc<Expression>),
}
impl ExpressionInner {
fn from_pair(pair: pest::iterators::Pair<Rule>) -> ExpressionInner {
match pair.as_rule() {
Rule::symbol => ExpressionInner::Symbol(string_from_pair(pair)),
Rule::integer_literal => ExpressionInner::IntegerLiteral(integer_from_pair(pair)),
Rule::string_literal => {
let s_with_quotes = string_from_pair(pair);
let mut chars = s_with_quotes.chars();
chars.next();
chars.next_back();
let s = chars.as_str();
ExpressionInner::StringLiteral(s.to_owned())
}
Rule::expression => {
let expression_inners: Vec<ExpressionInner> =
pair.into_inner().map(ExpressionInner::from_pair).collect();
ExpressionInner::Expression(expression_vec_to_tuple(&expression_inners))
}
rule => panic!("[ast] can't make an expression element from {:#?}", rule),
}
}
}
#[derive(Debug)]
pub enum Expression {
Unary(ExpressionInner),
Binary(ExpressionInner, ExpressionInner),
}
fn expression_vec_to_tuple(v: &[ExpressionInner]) -> Rc<Expression> {
match v.len() {
1 => Rc::new(Expression::Unary(v[0].clone())),
2 => Rc::new(Expression::Binary(v[0].clone(), v[1].clone())),
_ => {
let combined = ExpressionInner::Expression(Rc::new(Expression::Binary(
v[0].clone(),
v[1].clone(),
)));
let mut new_v = vec![combined];
for e in &v[2..] {
new_v.push(e.clone());
}
expression_vec_to_tuple(&new_v)
}
}
}
pub type IntegerLiteral = i64;
fn integer_from_pair(pair: pest::iterators::Pair<Rule>) -> i64 {
let s = pair.as_span().as_str();
s.parse().unwrap()
}
pub type StringLiteral = String;
fn string_from_pair(pair: pest::iterators::Pair<Rule>) -> String {
pair.as_span().as_str().to_owned()
}
pub type Symbol = String;
|
