Create Expr function helpers to create different Expr variants
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0065c2edf1
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13
src/ast.rs
13
src/ast.rs
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@ -33,7 +33,6 @@ pub enum Expr {
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//List(list::List<Expr>),
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Symbol(String),
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Str(String),
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Quote(Box<Expr>),
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Num(Number),
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Comment,
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Error(String),
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@ -47,6 +46,18 @@ impl Expr {
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pub fn make_list(first: Expr, rest: Expr) -> Expr {
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Expr::Cons(list::List::<Expr>::new(Box::new(first), Box::new(rest)))
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}
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pub fn make_symbol(v: String) -> Expr {
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Expr::Symbol(v)
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}
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pub fn make_string(v: String) -> Expr {
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Expr::Str(v)
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}
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pub fn make_number(n: Number) -> Expr {
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Expr::Num(n)
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}
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}
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impl Expression for Expr {
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@ -1,8 +1,4 @@
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use crate::ast::{Expr, Number};
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// Lst::List is the actual list implementation while
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// ast::Expr::List is a variant holding the actual
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// implementation.
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use crate::collections::list as lst;
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use std::io::{BufReader, Read};
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pub type ReadResult = Result<Expr, String>;
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@ -78,10 +74,10 @@ impl ExprReader {
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fn read_quoted_expr<T: Read>(&mut self, reader: &mut BufReader<T>) -> ReadResult {
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let rest = self.read_expr(reader)?;
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Ok(Expr::Cons(lst::List::<Expr>::new(
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Box::new(Expr::Symbol("quote".to_string())),
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Box::new(rest),
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)))
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Ok(Expr::make_list(
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Expr::make_symbol("quote".to_string()),
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rest,
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))
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}
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fn read_unquoted_expr<T: Read>(&mut self, reader: &mut BufReader<T>) -> ReadResult {
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@ -90,27 +86,27 @@ impl ExprReader {
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// Move forward in the buffer since we peeked it
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let _ = self.get_char(reader, true);
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let rest = self.read_expr(reader)?;
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Ok(Expr::Cons(lst::List::<Expr>::new(
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Box::new(Expr::Symbol("unquote-splicing".to_string())),
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Box::new(rest),
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)))
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Ok(Expr::make_list(
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Expr::make_symbol("unquote-splicing".to_string()),
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rest,
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))
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}
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_ => {
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let rest = self.read_expr(reader)?;
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Ok(Expr::Cons(lst::List::<Expr>::new(
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Box::new(Expr::Symbol("unquote".to_string())),
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Box::new(rest),
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)))
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Ok(Expr::make_list(
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Expr::make_symbol("unquote".to_string()),
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rest,
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))
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}
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}
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}
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fn read_quasiquoted_expr<T: Read>(&mut self, reader: &mut BufReader<T>) -> ReadResult {
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let rest = self.read_expr(reader)?;
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Ok(Expr::Cons(lst::List::<Expr>::new(
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Box::new(Expr::Symbol("quasiquote".to_string())),
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Box::new(rest),
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)))
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Ok(Expr::make_list(
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Expr::make_symbol("quasiquote".to_string()),
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rest,
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))
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}
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// TODO: We might want to replace Cons with an actual List struct
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@ -133,10 +129,7 @@ impl ExprReader {
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None => return Err("Unexpected EOF while parsing a list.".to_string()),
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};
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Ok(Expr::Cons(lst::List::<Expr>::new(
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Box::new(first),
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Box::new(rest),
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)))
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Ok(Expr::make_list(first, rest))
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}
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fn is_valid_for_identifier(&self, c: char) -> bool {
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@ -195,7 +188,7 @@ impl ExprReader {
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}
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}
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Ok(Expr::Symbol(symbol))
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Ok(Expr::make_symbol(symbol))
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}
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fn read_escape_char<T: Read>(&mut self, reader: &mut BufReader<T>) -> Option<char> {
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@ -232,7 +225,7 @@ impl ExprReader {
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None => return Err("Unexpected EOF while scanning a string".to_string()),
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}
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}
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Ok(Expr::Str(string))
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Ok(Expr::make_string(string))
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}
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fn read_number<T: Read>(&mut self, reader: &mut BufReader<T>, neg: bool) -> ReadResult {
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@ -257,9 +250,13 @@ impl ExprReader {
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}
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}
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if is_double {
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Ok(Expr::Num(Number::Float(string.parse::<f64>().unwrap())))
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Ok(Expr::make_number(Number::Float(
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string.parse::<f64>().unwrap(),
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)))
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} else {
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Ok(Expr::Num(Number::Integer(string.parse::<i64>().unwrap())))
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Ok(Expr::make_number(Number::Integer(
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string.parse::<i64>().unwrap(),
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)))
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}
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}
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